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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.21 by root, Wed Jul 13 00:13:09 2005 UTC vs.
Revision 1.89 by root, Sun Oct 29 11:03:18 2006 UTC

…		…
15		15
16	aio_read $fh, 30000, 1024, $buffer, 0, sub {	16	aio_read $fh, 30000, 1024, $buffer, 0, sub {
17	$_[0] > 0 or die "read error: $!";	17	$_[0] > 0 or die "read error: $!";
18	};	18	};
19		19
20	# Event	20	# version 2+ has request and group objects
		21	use IO::AIO 2;
		22
		23	aioreq_pri 4; # give next request a very high priority
		24	my $req = aio_unlink "/tmp/file", sub { };
		25	$req->cancel; # cancel request if still in queue
		26
		27	my $grp = aio_group sub { print "all stats done\n" };
		28	add $grp aio_stat "..." for ...;
		29
		30	# AnyEvent integration
		31	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
		32	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
		33
		34	# Event integration
21	Event->io (fd => IO::AIO::poll_fileno,	35	Event->io (fd => IO::AIO::poll_fileno,
22	poll => 'r',	36	poll => 'r',
23	cb => \&IO::AIO::poll_cb);	37	cb => \&IO::AIO::poll_cb);
24		38
25	# Glib/Gtk2	39	# Glib/Gtk2 integration
26	add_watch Glib::IO IO::AIO::poll_fileno,	40	add_watch Glib::IO IO::AIO::poll_fileno,
27	in => sub { IO::AIO::poll_cb, 1 };	41	in => sub { IO::AIO::poll_cb; 1 };
28		42
29	# Tk	43	# Tk integration
30	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",	44	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
31	readable => \&IO::AIO::poll_cb);	45	readable => \&IO::AIO::poll_cb);
32		46
33	# Danga::Socket	47	# Danga::Socket integration
34	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	48	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
35	\&IO::AIO::poll_cb);	49	\&IO::AIO::poll_cb);
36		50
37
38	=head1 DESCRIPTION	51	=head1 DESCRIPTION
39		52
40	This module implements asynchronous I/O using whatever means your	53	This module implements asynchronous I/O using whatever means your
41	operating system supports.	54	operating system supports.
42		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
43	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
44	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
45	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
46	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
47	aio functions available on many operating systems. However, they are often	76	functions available on many operating systems. However, they are often
48	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
49	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
50	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.
51		81
52	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-)
53	currently not reentrant, so use appropriate locking yourself.	83	threads, it is currently not reentrant in any way, so use appropriate
		84	locking yourself, always call C<poll_cb> from within the same thread, or
		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).
		180
		181	=back
54		182
55	=cut	183	=cut
56		184
57	package IO::AIO;	185	package IO::AIO;
58		186
		187	no warnings;
		188	use strict 'vars';
		189
59	use base 'Exporter';	190	use base 'Exporter';
60		191
61	use Fcntl ();
62
63	BEGIN {	192	BEGIN {
64	$VERSION = 0.9;	193	our $VERSION = '2.1';
65		194
66	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink	195	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
67	aio_fsync aio_fdatasync aio_readahead);	196	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
68	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	197	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
		198	aio_copy aio_group aio_nop aio_mknod);
		199	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		200	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		201	min_parallel max_parallel max_idle
		202	nreqs nready npending nthreads
		203	max_poll_time max_poll_reqs);
		204
		205	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
69		206
70	require XSLoader;	207	require XSLoader;
71	XSLoader::load IO::AIO, $VERSION;	208	XSLoader::load ("IO::AIO", $VERSION);
72	}	209	}
73		210
74	=head1 FUNCTIONS	211	=head1 FUNCTIONS
75		212
76	=head2 AIO FUNCTIONS	213	=head2 AIO REQUEST FUNCTIONS
77		214
78	All the C<aio_*> calls are more or less thin wrappers around the syscall	215	All the C<aio_*> calls are more or less thin wrappers around the syscall
79	with the same name (sans C<aio_>). The arguments are similar or identical,	216	with the same name (sans C<aio_>). The arguments are similar or identical,
80	and they all accept an additional (and optional) C<$callback> argument	217	and they all accept an additional (and optional) C<$callback> argument
81	which must be a code reference. This code reference will get called with	218	which must be a code reference. This code reference will get called with
82	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	219	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
83	perl, which usually delivers "false") as it's sole argument when the given	220	perl, which usually delivers "false") as it's sole argument when the given
84	syscall has been executed asynchronously.	221	syscall has been executed asynchronously.
85		222
86	All functions that expect a filehandle will also accept a file descriptor.	223	All functions expecting a filehandle keep a copy of the filehandle
		224	internally until the request has finished.
87		225
		226	All functions return request objects of type L<IO::AIO::REQ> that allow
		227	further manipulation of those requests while they are in-flight.
		228
88	The filenames you pass to these routines I<must> be absolute. The reason	229	The pathnames you pass to these routines I<must> be absolute and
89	for this is that at the time the request is being executed, the current	230	encoded as octets. The reason for the former is that at the time the
90	working directory could have changed. Alternatively, you can make sure	231	request is being executed, the current working directory could have
91	that you never change the current working directory.	232	changed. Alternatively, you can make sure that you never change the
		233	current working directory anywhere in the program and then use relative
		234	paths.
		235
		236	To encode pathnames as octets, either make sure you either: a) always pass
		237	in filenames you got from outside (command line, readdir etc.) without
		238	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
		239	your pathnames to the locale (or other) encoding in effect in the user
		240	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
		241	use something else to ensure your scalar has the correct contents.
		242
		243	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		244	handles correctly wether it is set or not.
92		245
93	=over 4	246	=over 4
94		247
		248	=item $prev_pri = aioreq_pri [$pri]
		249
		250	Returns the priority value that would be used for the next request and, if
		251	C<$pri> is given, sets the priority for the next aio request.
		252
		253	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		254	and C<4>, respectively. Requests with higher priority will be serviced
		255	first.
		256
		257	The priority will be reset to C<0> after each call to one of the C<aio_*>
		258	functions.
		259
		260	Example: open a file with low priority, then read something from it with
		261	higher priority so the read request is serviced before other low priority
		262	open requests (potentially spamming the cache):
		263
		264	aioreq_pri -3;
		265	aio_open ..., sub {
		266	return unless $_[0];
		267
		268	aioreq_pri -2;
		269	aio_read $_[0], ..., sub {
		270	...
		271	};
		272	};
		273
		274	=item aioreq_nice $pri_adjust
		275
		276	Similar to C<aioreq_pri>, but subtracts the given value from the current
		277	priority, so the effect is cumulative.
		278
95	=item aio_open $pathname, $flags, $mode, $callback	279	=item aio_open $pathname, $flags, $mode, $callback->($fh)
96		280
97	Asynchronously open or create a file and call the callback with a newly	281	Asynchronously open or create a file and call the callback with a newly
98	created filehandle for the file.	282	created filehandle for the file.
99		283
100	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	284	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
…		…
117	} else {	301	} else {
118	die "open failed: $!\n";	302	die "open failed: $!\n";
119	}	303	}
120	};	304	};
121		305
122	=item aio_close $fh, $callback	306	=item aio_close $fh, $callback->($status)
123		307
124	Asynchronously close a file and call the callback with the result	308	Asynchronously close a file and call the callback with the result
125	code. I<WARNING:> although accepted, you should not pass in a perl	309	code. I<WARNING:> although accepted, you should not pass in a perl
126	filehandle here, as perl will likely close the file descriptor another	310	filehandle here, as perl will likely close the file descriptor another
127	time when the filehandle is destroyed. Normally, you can safely call perls	311	time when the filehandle is destroyed. Normally, you can safely call perls
128	C<close> or just let filehandles go out of scope.	312	C<close> or just let filehandles go out of scope.
129		313
130	This is supposed to be a bug in the API, so that might change. It's	314	This is supposed to be a bug in the API, so that might change. It's
131	therefore best to avoid this function.	315	therefore best to avoid this function.
132		316
133	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback	317	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
134		318
135	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback	319	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
136		320
137	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	321	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
138	into the scalar given by C<data> and offset C<dataoffset> and calls the	322	into the scalar given by C<data> and offset C<dataoffset> and calls the
139	callback without the actual number of bytes read (or -1 on error, just	323	callback without the actual number of bytes read (or -1 on error, just
140	like the syscall).	324	like the syscall).
141		325
		326	The C<$data> scalar I<MUST NOT> be modified in any way while the request
		327	is outstanding. Modifying it can result in segfaults or WW3 (if the
		328	necessary/optional hardware is installed).
		329
142	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	330	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
143	offset C<0> within the scalar:	331	offset C<0> within the scalar:
144		332
145	aio_read $fh, 7, 15, $buffer, 0, sub {	333	aio_read $fh, 7, 15, $buffer, 0, sub {
146	$_[0] > 0 or die "read error: $!";	334	$_[0] > 0 or die "read error: $!";
147	print "read $_[0] bytes: <$buffer>\n";	335	print "read $_[0] bytes: <$buffer>\n";
148	};	336	};
149		337
		338	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		339
		340	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
		341	reading at byte offset C<$in_offset>, and starts writing at the current
		342	file offset of C<$out_fh>. Because of that, it is not safe to issue more
		343	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
		344	other.
		345
		346	This call tries to make use of a native C<sendfile> syscall to provide
		347	zero-copy operation. For this to work, C<$out_fh> should refer to a
		348	socket, and C<$in_fh> should refer to mmap'able file.
		349
		350	If the native sendfile call fails or is not implemented, it will be
		351	emulated, so you can call C<aio_sendfile> on any type of filehandle
		352	regardless of the limitations of the operating system.
		353
		354	Please note, however, that C<aio_sendfile> can read more bytes from
		355	C<$in_fh> than are written, and there is no way to find out how many
		356	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
		357	provides the number of bytes written to C<$out_fh>. Only if the result
		358	value equals C<$length> one can assume that C<$length> bytes have been
		359	read.
		360
150	=item aio_readahead $fh,$offset,$length, $callback	361	=item aio_readahead $fh,$offset,$length, $callback->($retval)
151
152	Asynchronously reads the specified byte range into the page cache, using
153	the C<readahead> syscall. If that syscall doesn't exist (likely if your OS
154	isn't Linux) the status will be C<-1> and C<$!> is set to C<ENOSYS>.
155		362
156	C<aio_readahead> populates the page cache with data from a file so that	363	C<aio_readahead> populates the page cache with data from a file so that
157	subsequent reads from that file will not block on disk I/O. The C<$offset>	364	subsequent reads from that file will not block on disk I/O. The C<$offset>
158	argument specifies the starting point from which data is to be read and	365	argument specifies the starting point from which data is to be read and
159	C<$length> specifies the number of bytes to be read. I/O is performed in	366	C<$length> specifies the number of bytes to be read. I/O is performed in
160	whole pages, so that offset is effectively rounded down to a page boundary	367	whole pages, so that offset is effectively rounded down to a page boundary
161	and bytes are read up to the next page boundary greater than or equal to	368	and bytes are read up to the next page boundary greater than or equal to
162	(off-set+length). C<aio_readahead> does not read beyond the end of the	369	(off-set+length). C<aio_readahead> does not read beyond the end of the
163	file. The current file offset of the file is left unchanged.	370	file. The current file offset of the file is left unchanged.
164		371
		372	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
		373	emulated by simply reading the data, which would have a similar effect.
		374
165	=item aio_stat $fh_or_path, $callback	375	=item aio_stat $fh_or_path, $callback->($status)
166		376
167	=item aio_lstat $fh, $callback	377	=item aio_lstat $fh, $callback->($status)
168		378
169	Works like perl's C<stat> or C<lstat> in void context. The callback will	379	Works like perl's C<stat> or C<lstat> in void context. The callback will
170	be called after the stat and the results will be available using C<stat _>	380	be called after the stat and the results will be available using C<stat _>
171	or C<-s _> etc...	381	or C<-s _> etc...
172		382
…		…
182	aio_stat "/etc/passwd", sub {	392	aio_stat "/etc/passwd", sub {
183	$_[0] and die "stat failed: $!";	393	$_[0] and die "stat failed: $!";
184	print "size is ", -s _, "\n";	394	print "size is ", -s _, "\n";
185	};	395	};
186		396
187	=item aio_unlink $pathname, $callback	397	=item aio_unlink $pathname, $callback->($status)
188		398
189	Asynchronously unlink (delete) a file and call the callback with the	399	Asynchronously unlink (delete) a file and call the callback with the
190	result code.	400	result code.
191		401
		402	=item aio_mknod $path, $mode, $dev, $callback->($status)
		403
		404	[EXPERIMENTAL]
		405
		406	Asynchronously create a device node (or fifo). See mknod(2).
		407
		408	The only (POSIX-) portable way of calling this function is:
		409
		410	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		411
		412	=item aio_link $srcpath, $dstpath, $callback->($status)
		413
		414	Asynchronously create a new link to the existing object at C<$srcpath> at
		415	the path C<$dstpath> and call the callback with the result code.
		416
		417	=item aio_symlink $srcpath, $dstpath, $callback->($status)
		418
		419	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
		420	the path C<$dstpath> and call the callback with the result code.
		421
		422	=item aio_rename $srcpath, $dstpath, $callback->($status)
		423
		424	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
		425	rename(2) and call the callback with the result code.
		426
		427	=item aio_rmdir $pathname, $callback->($status)
		428
		429	Asynchronously rmdir (delete) a directory and call the callback with the
		430	result code.
		431
		432	=item aio_readdir $pathname, $callback->($entries)
		433
		434	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
		435	directory (i.e. opendir + readdir + closedir). The entries will not be
		436	sorted, and will B<NOT> include the C<.> and C<..> entries.
		437
		438	The callback a single argument which is either C<undef> or an array-ref
		439	with the filenames.
		440
		441	=item aio_copy $srcpath, $dstpath, $callback->($status)
		442
		443	Try to copy the I<file> (directories not supported as either source or
		444	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		445	the C<0> (error) or C<-1> ok.
		446
		447	This is a composite request that it creates the destination file with
		448	mode 0200 and copies the contents of the source file into it using
		449	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		450	uid/gid, in that order.
		451
		452	If an error occurs, the partial destination file will be unlinked, if
		453	possible, except when setting atime, mtime, access mode and uid/gid, where
		454	errors are being ignored.
		455
		456	=cut
		457
		458	sub aio_copy($$;$) {
		459	my ($src, $dst, $cb) = @_;
		460
		461	my $pri = aioreq_pri;
		462	my $grp = aio_group $cb;
		463
		464	aioreq_pri $pri;
		465	add $grp aio_open $src, O_RDONLY, 0, sub {
		466	if (my $src_fh = $_[0]) {
		467	my @stat = stat $src_fh;
		468
		469	aioreq_pri $pri;
		470	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		471	if (my $dst_fh = $_[0]) {
		472	aioreq_pri $pri;
		473	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		474	if ($_[0] == $stat[7]) {
		475	$grp->result (0);
		476	close $src_fh;
		477
		478	# those should not normally block. should. should.
		479	utime $stat[8], $stat[9], $dst;
		480	chmod $stat[2] & 07777, $dst_fh;
		481	chown $stat[4], $stat[5], $dst_fh;
		482	close $dst_fh;
		483	} else {
		484	$grp->result (-1);
		485	close $src_fh;
		486	close $dst_fh;
		487
		488	aioreq $pri;
		489	add $grp aio_unlink $dst;
		490	}
		491	};
		492	} else {
		493	$grp->result (-1);
		494	}
		495	},
		496
		497	} else {
		498	$grp->result (-1);
		499	}
		500	};
		501
		502	$grp
		503	}
		504
		505	=item aio_move $srcpath, $dstpath, $callback->($status)
		506
		507	Try to move the I<file> (directories not supported as either source or
		508	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		509	the C<0> (error) or C<-1> ok.
		510
		511	This is a composite request that tries to rename(2) the file first. If
		512	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		513	that is successful, unlinking the C<$srcpath>.
		514
		515	=cut
		516
		517	sub aio_move($$;$) {
		518	my ($src, $dst, $cb) = @_;
		519
		520	my $pri = aioreq_pri;
		521	my $grp = aio_group $cb;
		522
		523	aioreq_pri $pri;
		524	add $grp aio_rename $src, $dst, sub {
		525	if ($_[0] && $! == EXDEV) {
		526	aioreq_pri $pri;
		527	add $grp aio_copy $src, $dst, sub {
		528	$grp->result ($_[0]);
		529
		530	if (!$_[0]) {
		531	aioreq_pri $pri;
		532	add $grp aio_unlink $src;
		533	}
		534	};
		535	} else {
		536	$grp->result ($_[0]);
		537	}
		538	};
		539
		540	$grp
		541	}
		542
		543	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		544
		545	Scans a directory (similar to C<aio_readdir>) but additionally tries to
		546	efficiently separate the entries of directory C<$path> into two sets of
		547	names, directories you can recurse into (directories), and ones you cannot
		548	recurse into (everything else, including symlinks to directories).
		549
		550	C<aio_scandir> is a composite request that creates of many sub requests_
		551	C<$maxreq> specifies the maximum number of outstanding aio requests that
		552	this function generates. If it is C<< <= 0 >>, then a suitable default
		553	will be chosen (currently 4).
		554
		555	On error, the callback is called without arguments, otherwise it receives
		556	two array-refs with path-relative entry names.
		557
		558	Example:
		559
		560	aio_scandir $dir, 0, sub {
		561	my ($dirs, $nondirs) = @_;
		562	print "real directories: @$dirs\n";
		563	print "everything else: @$nondirs\n";
		564	};
		565
		566	Implementation notes.
		567
		568	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
		569
		570	After reading the directory, the modification time, size etc. of the
		571	directory before and after the readdir is checked, and if they match (and
		572	isn't the current time), the link count will be used to decide how many
		573	entries are directories (if >= 2). Otherwise, no knowledge of the number
		574	of subdirectories will be assumed.
		575
		576	Then entries will be sorted into likely directories (everything without
		577	a non-initial dot currently) and likely non-directories (everything
		578	else). Then every entry plus an appended C</.> will be C<stat>'ed,
		579	likely directories first. If that succeeds, it assumes that the entry
		580	is a directory or a symlink to directory (which will be checked
		581	seperately). This is often faster than stat'ing the entry itself because
		582	filesystems might detect the type of the entry without reading the inode
		583	data (e.g. ext2fs filetype feature).
		584
		585	If the known number of directories (link count - 2) has been reached, the
		586	rest of the entries is assumed to be non-directories.
		587
		588	This only works with certainty on POSIX (= UNIX) filesystems, which
		589	fortunately are the vast majority of filesystems around.
		590
		591	It will also likely work on non-POSIX filesystems with reduced efficiency
		592	as those tend to return 0 or 1 as link counts, which disables the
		593	directory counting heuristic.
		594
		595	=cut
		596
		597	sub aio_scandir($$$) {
		598	my ($path, $maxreq, $cb) = @_;
		599
		600	my $pri = aioreq_pri;
		601
		602	my $grp = aio_group $cb;
		603
		604	$maxreq = 4 if $maxreq <= 0;
		605
		606	# stat once
		607	aioreq_pri $pri;
		608	add $grp aio_stat $path, sub {
		609	return $grp->result () if $_[0];
		610	my $now = time;
		611	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		612
		613	# read the directory entries
		614	aioreq_pri $pri;
		615	add $grp aio_readdir $path, sub {
		616	my $entries = shift
		617	or return $grp->result ();
		618
		619	# stat the dir another time
		620	aioreq_pri $pri;
		621	add $grp aio_stat $path, sub {
		622	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		623
		624	my $ndirs;
		625
		626	# take the slow route if anything looks fishy
		627	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
		628	$ndirs = -1;
		629	} else {
		630	# if nlink == 2, we are finished
		631	# on non-posix-fs's, we rely on nlink < 2
		632	$ndirs = (stat _)[3] - 2
		633	or return $grp->result ([], $entries);
		634	}
		635
		636	# sort into likely dirs and likely nondirs
		637	# dirs == files without ".", short entries first
		638	$entries = [map $_->[0],
		639	sort { $b->[1] cmp $a->[1] }
		640	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
		641	@$entries];
		642
		643	my (@dirs, @nondirs);
		644
		645	my $statgrp = add $grp aio_group sub {
		646	$grp->result (\@dirs, \@nondirs);
		647	};
		648
		649	limit $statgrp $maxreq;
		650	feed $statgrp sub {
		651	return unless @$entries;
		652	my $entry = pop @$entries;
		653
		654	aioreq_pri $pri;
		655	add $statgrp aio_stat "$path/$entry/.", sub {
		656	if ($_[0] < 0) {
		657	push @nondirs, $entry;
		658	} else {
		659	# need to check for real directory
		660	aioreq_pri $pri;
		661	add $statgrp aio_lstat "$path/$entry", sub {
		662	if (-d _) {
		663	push @dirs, $entry;
		664
		665	unless (--$ndirs) {
		666	push @nondirs, @$entries;
		667	feed $statgrp;
		668	}
		669	} else {
		670	push @nondirs, $entry;
		671	}
		672	}
		673	}
		674	};
		675	};
		676	};
		677	};
		678	};
		679
		680	$grp
		681	}
		682
192	=item aio_fsync $fh, $callback	683	=item aio_fsync $fh, $callback->($status)
193		684
194	Asynchronously call fsync on the given filehandle and call the callback	685	Asynchronously call fsync on the given filehandle and call the callback
195	with the fsync result code.	686	with the fsync result code.
196		687
197	=item aio_fdatasync $fh, $callback	688	=item aio_fdatasync $fh, $callback->($status)
198		689
199	Asynchronously call fdatasync on the given filehandle and call the	690	Asynchronously call fdatasync on the given filehandle and call the
200	callback with the fdatasync result code. Might set C<$!> to C<ENOSYS> if	691	callback with the fdatasync result code.
201	C<fdatasync> is not available.	692
		693	If this call isn't available because your OS lacks it or it couldn't be
		694	detected, it will be emulated by calling C<fsync> instead.
		695
		696	=item aio_group $callback->(...)
		697
		698	This is a very special aio request: Instead of doing something, it is a
		699	container for other aio requests, which is useful if you want to bundle
		700	many requests into a single, composite, request with a definite callback
		701	and the ability to cancel the whole request with its subrequests.
		702
		703	Returns an object of class L<IO::AIO::GRP>. See its documentation below
		704	for more info.
		705
		706	Example:
		707
		708	my $grp = aio_group sub {
		709	print "all stats done\n";
		710	};
		711
		712	add $grp
		713	(aio_stat ...),
		714	(aio_stat ...),
		715	...;
		716
		717	=item aio_nop $callback->()
		718
		719	This is a special request - it does nothing in itself and is only used for
		720	side effects, such as when you want to add a dummy request to a group so
		721	that finishing the requests in the group depends on executing the given
		722	code.
		723
		724	While this request does nothing, it still goes through the execution
		725	phase and still requires a worker thread. Thus, the callback will not
		726	be executed immediately but only after other requests in the queue have
		727	entered their execution phase. This can be used to measure request
		728	latency.
		729
		730	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
		731
		732	Mainly used for debugging and benchmarking, this aio request puts one of
		733	the request workers to sleep for the given time.
		734
		735	While it is theoretically handy to have simple I/O scheduling requests
		736	like sleep and file handle readable/writable, the overhead this creates is
		737	immense (it blocks a thread for a long time) so do not use this function
		738	except to put your application under artificial I/O pressure.
202		739
203	=back	740	=back
204		741
		742	=head2 IO::AIO::REQ CLASS
		743
		744	All non-aggregate C<aio_*> functions return an object of this class when
		745	called in non-void context.
		746
		747	=over 4
		748
		749	=item cancel $req
		750
		751	Cancels the request, if possible. Has the effect of skipping execution
		752	when entering the B<execute> state and skipping calling the callback when
		753	entering the the B<result> state, but will leave the request otherwise
		754	untouched. That means that requests that currently execute will not be
		755	stopped and resources held by the request will not be freed prematurely.
		756
		757	=item cb $req $callback->(...)
		758
		759	Replace (or simply set) the callback registered to the request.
		760
		761	=back
		762
		763	=head2 IO::AIO::GRP CLASS
		764
		765	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
		766	objects of this class, too.
		767
		768	A IO::AIO::GRP object is a special request that can contain multiple other
		769	aio requests.
		770
		771	You create one by calling the C<aio_group> constructing function with a
		772	callback that will be called when all contained requests have entered the
		773	C<done> state:
		774
		775	my $grp = aio_group sub {
		776	print "all requests are done\n";
		777	};
		778
		779	You add requests by calling the C<add> method with one or more
		780	C<IO::AIO::REQ> objects:
		781
		782	$grp->add (aio_unlink "...");
		783
		784	add $grp aio_stat "...", sub {
		785	$_[0] or return $grp->result ("error");
		786
		787	# add another request dynamically, if first succeeded
		788	add $grp aio_open "...", sub {
		789	$grp->result ("ok");
		790	};
		791	};
		792
		793	This makes it very easy to create composite requests (see the source of
		794	C<aio_move> for an application) that work and feel like simple requests.
		795
		796	=over 4
		797
		798	=item * The IO::AIO::GRP objects will be cleaned up during calls to
		799	C<IO::AIO::poll_cb>, just like any other request.
		800
		801	=item * They can be canceled like any other request. Canceling will cancel not
		802	only the request itself, but also all requests it contains.
		803
		804	=item * They can also can also be added to other IO::AIO::GRP objects.
		805
		806	=item * You must not add requests to a group from within the group callback (or
		807	any later time).
		808
		809	=back
		810
		811	Their lifetime, simplified, looks like this: when they are empty, they
		812	will finish very quickly. If they contain only requests that are in the
		813	C<done> state, they will also finish. Otherwise they will continue to
		814	exist.
		815
		816	That means after creating a group you have some time to add requests. And
		817	in the callbacks of those requests, you can add further requests to the
		818	group. And only when all those requests have finished will the the group
		819	itself finish.
		820
		821	=over 4
		822
		823	=item add $grp ...
		824
		825	=item $grp->add (...)
		826
		827	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		828	be added, including other groups, as long as you do not create circular
		829	dependencies.
		830
		831	Returns all its arguments.
		832
		833	=item $grp->cancel_subs
		834
		835	Cancel all subrequests and clears any feeder, but not the group request
		836	itself. Useful when you queued a lot of events but got a result early.
		837
		838	=item $grp->result (...)
		839
		840	Set the result value(s) that will be passed to the group callback when all
		841	subrequests have finished and set thre groups errno to the current value
		842	of errno (just like calling C<errno> without an error number). By default,
		843	no argument will be passed and errno is zero.
		844
		845	=item $grp->errno ([$errno])
		846
		847	Sets the group errno value to C<$errno>, or the current value of errno
		848	when the argument is missing.
		849
		850	Every aio request has an associated errno value that is restored when
		851	the callback is invoked. This method lets you change this value from its
		852	default (0).
		853
		854	Calling C<result> will also set errno, so make sure you either set C<$!>
		855	before the call to C<result>, or call c<errno> after it.
		856
		857	=item feed $grp $callback->($grp)
		858
		859	Sets a feeder/generator on this group: every group can have an attached
		860	generator that generates requests if idle. The idea behind this is that,
		861	although you could just queue as many requests as you want in a group,
		862	this might starve other requests for a potentially long time. For
		863	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		864	requests, delaying any later requests for a long time.
		865
		866	To avoid this, and allow incremental generation of requests, you can
		867	instead a group and set a feeder on it that generates those requests. The
		868	feed callback will be called whenever there are few enough (see C<limit>,
		869	below) requests active in the group itself and is expected to queue more
		870	requests.
		871
		872	The feed callback can queue as many requests as it likes (i.e. C<add> does
		873	not impose any limits).
		874
		875	If the feed does not queue more requests when called, it will be
		876	automatically removed from the group.
		877
		878	If the feed limit is C<0>, it will be set to C<2> automatically.
		879
		880	Example:
		881
		882	# stat all files in @files, but only ever use four aio requests concurrently:
		883
		884	my $grp = aio_group sub { print "finished\n" };
		885	limit $grp 4;
		886	feed $grp sub {
		887	my $file = pop @files
		888	or return;
		889
		890	add $grp aio_stat $file, sub { ... };
		891	};
		892
		893	=item limit $grp $num
		894
		895	Sets the feeder limit for the group: The feeder will be called whenever
		896	the group contains less than this many requests.
		897
		898	Setting the limit to C<0> will pause the feeding process.
		899
		900	=back
		901
205	=head2 SUPPORT FUNCTIONS	902	=head2 SUPPORT FUNCTIONS
		903
		904	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
206		905
207	=over 4	906	=over 4
208		907
209	=item $fileno = IO::AIO::poll_fileno	908	=item $fileno = IO::AIO::poll_fileno
210		909
…		…
215		914
216	See C<poll_cb> for an example.	915	See C<poll_cb> for an example.
217		916
218	=item IO::AIO::poll_cb	917	=item IO::AIO::poll_cb
219		918
220	Process all outstanding events on the result pipe. You have to call this	919	Process some outstanding events on the result pipe. You have to call this
221	regularly. Returns the number of events processed. Returns immediately	920	regularly. Returns the number of events processed. Returns immediately
222	when no events are outstanding.	921	when no events are outstanding. The amount of events processed depends on
		922	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		923
		924	If not all requests were processed for whatever reason, the filehandle
		925	will still be ready when C<poll_cb> returns.
223		926
224	Example: Install an Event watcher that automatically calls	927	Example: Install an Event watcher that automatically calls
225	IO::AIO::poll_cb with high priority:	928	IO::AIO::poll_cb with high priority:
226		929
227	Event->io (fd => IO::AIO::poll_fileno,	930	Event->io (fd => IO::AIO::poll_fileno,
228	poll => 'r', async => 1,	931	poll => 'r', async => 1,
229	cb => \&IO::AIO::poll_cb);	932	cb => \&IO::AIO::poll_cb);
230		933
		934	=item IO::AIO::max_poll_reqs $nreqs
		935
		936	=item IO::AIO::max_poll_time $seconds
		937
		938	These set the maximum number of requests (default C<0>, meaning infinity)
		939	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		940	the maximum amount of time (default C<0>, meaning infinity) spent in
		941	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		942	of time C<poll_cb> is allowed to use).
		943
		944	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		945	syscall per request processed, which is not normally a problem unless your
		946	callbacks are really really fast or your OS is really really slow (I am
		947	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		948
		949	Setting these is useful if you want to ensure some level of
		950	interactiveness when perl is not fast enough to process all requests in
		951	time.
		952
		953	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		954
		955	Example: Install an Event watcher that automatically calls
		956	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		957	program get the CPU sometimes even under high AIO load.
		958
		959	# try not to spend much more than 0.1s in poll_cb
		960	IO::AIO::max_poll_time 0.1;
		961
		962	# use a low priority so other tasks have priority
		963	Event->io (fd => IO::AIO::poll_fileno,
		964	poll => 'r', nice => 1,
		965	cb => &IO::AIO::poll_cb);
		966
231	=item IO::AIO::poll_wait	967	=item IO::AIO::poll_wait
232		968
233	Wait till the result filehandle becomes ready for reading (simply does a	969	Wait till the result filehandle becomes ready for reading (simply does a
234	C<select> on the filehandle. This is useful if you want to synchronously wait	970	C<select> on the filehandle. This is useful if you want to synchronously
235	for some requests to finish).	971	wait for some requests to finish).
236		972
237	See C<nreqs> for an example.	973	See C<nreqs> for an example.
238		974
		975	=item IO::AIO::poll
		976
		977	Waits until some requests have been handled.
		978
		979	Strictly equivalent to:
		980
		981	IO::AIO::poll_wait, IO::AIO::poll_cb
		982	if IO::AIO::nreqs;
		983
239	=item IO::AIO::nreqs	984	=item IO::AIO::flush
240		985
241	Returns the number of requests currently outstanding (i.e. for which their	986	Wait till all outstanding AIO requests have been handled.
242	callback has not been invoked yet).
243		987
244	Example: wait till there are no outstanding requests anymore:	988	Strictly equivalent to:
245		989
246	IO::AIO::poll_wait, IO::AIO::poll_cb	990	IO::AIO::poll_wait, IO::AIO::poll_cb
247	while IO::AIO::nreqs;	991	while IO::AIO::nreqs;
248		992
		993	=head3 CONTROLLING THE NUMBER OF THREADS
		994
		995	=item IO::AIO::min_parallel $nthreads
		996
		997	Set the minimum number of AIO threads to C<$nthreads>. The current
		998	default is C<8>, which means eight asynchronous operations can execute
		999	concurrently at any one time (the number of outstanding requests,
		1000	however, is unlimited).
		1001
		1002	IO::AIO starts threads only on demand, when an AIO request is queued and
		1003	no free thread exists. Please note that queueing up a hundred requests can
		1004	create demand for a hundred threads, even if it turns out that everything
		1005	is in the cache and could have been processed faster by a single thread.
		1006
		1007	It is recommended to keep the number of threads relatively low, as some
		1008	Linux kernel versions will scale negatively with the number of threads
		1009	(higher parallelity => MUCH higher latency). With current Linux 2.6
		1010	versions, 4-32 threads should be fine.
		1011
		1012	Under most circumstances you don't need to call this function, as the
		1013	module selects a default that is suitable for low to moderate load.
		1014
		1015	=item IO::AIO::max_parallel $nthreads
		1016
		1017	Sets the maximum number of AIO threads to C<$nthreads>. If more than the
		1018	specified number of threads are currently running, this function kills
		1019	them. This function blocks until the limit is reached.
		1020
		1021	While C<$nthreads> are zero, aio requests get queued but not executed
		1022	until the number of threads has been increased again.
		1023
		1024	This module automatically runs C<max_parallel 0> at program end, to ensure
		1025	that all threads are killed and that there are no outstanding requests.
		1026
		1027	Under normal circumstances you don't need to call this function.
		1028
		1029	=item IO::AIO::max_idle $nthreads
		1030
		1031	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1032	threads that did not get a request to process within 10 seconds). That
		1033	means if a thread becomes idle while C<$nthreads> other threads are also
		1034	idle, it will free its resources and exit.
		1035
		1036	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1037	to allow for extremely high load situations, but want to free resources
		1038	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1039
		1040	The default is probably ok in most situations, especially if thread
		1041	creation is fast. If thread creation is very slow on your system you might
		1042	want to use larger values.
		1043
		1044	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		1045
		1046	This is a very bad function to use in interactive programs because it
		1047	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1048	use an C<aio_group> together with a feed callback.
		1049
		1050	Sets the maximum number of outstanding requests to C<$nreqs>. If you
		1051	to queue up more than this number of requests, the next call to the
		1052	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1053	function will block until the limit is no longer exceeded.
		1054
		1055	The default value is very large, so there is no practical limit on the
		1056	number of outstanding requests.
		1057
		1058	You can still queue as many requests as you want. Therefore,
		1059	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		1060	as a stop gap to shield against fatal memory overflow (with large values).
		1061
		1062	=head3 STATISTICAL INFORMATION
		1063
249	=item IO::AIO::flush	1064	=item IO::AIO::nreqs
250		1065
251	Wait till all outstanding AIO requests have been handled.	1066	Returns the number of requests currently in the ready, execute or pending
		1067	states (i.e. for which their callback has not been invoked yet).
252		1068
253	Strictly equivalent to:	1069	Example: wait till there are no outstanding requests anymore:
254		1070
255	IO::AIO::poll_wait, IO::AIO::poll_cb	1071	IO::AIO::poll_wait, IO::AIO::poll_cb
256	while IO::AIO::nreqs;	1072	while IO::AIO::nreqs;
257		1073
		1074	=item IO::AIO::nready
		1075
		1076	Returns the number of requests currently in the ready state (not yet
		1077	executed).
		1078
258	=item IO::AIO::poll	1079	=item IO::AIO::npending
259		1080
260	Waits until some requests have been handled.	1081	Returns the number of requests currently in the pending state (executed,
261		1082	but not yet processed by poll_cb).
262	Strictly equivalent to:
263
264	IO::AIO::poll_wait, IO::AIO::poll_cb
265	if IO::AIO::nreqs;
266
267	=item IO::AIO::min_parallel $nthreads
268
269	Set the minimum number of AIO threads to C<$nthreads>. The default is
270	C<1>, which means a single asynchronous operation can be done at one time
271	(the number of outstanding operations, however, is unlimited).
272
273	It is recommended to keep the number of threads low, as some Linux
274	kernel versions will scale negatively with the number of threads (higher
275	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
276	threads should be fine.
277
278	Under normal circumstances you don't need to call this function, as this
279	module automatically starts some threads (the exact number might change,
280	and is currently 4).
281
282	=item IO::AIO::max_parallel $nthreads
283
284	Sets the maximum number of AIO threads to C<$nthreads>. If more than
285	the specified number of threads are currently running, kill them. This
286	function blocks until the limit is reached.
287
288	This module automatically runs C<max_parallel 0> at program end, to ensure
289	that all threads are killed and that there are no outstanding requests.
290
291	Under normal circumstances you don't need to call this function.
292
293	=item $oldnreqs = IO::AIO::max_outstanding $nreqs
294
295	Sets the maximum number of outstanding requests to C<$nreqs>. If you
296	try to queue up more than this number of requests, the caller will block until
297	some requests have been handled.
298
299	The default is very large, so normally there is no practical limit. If you
300	queue up many requests in a loop it it often improves speed if you set
301	this to a relatively low number, such as C<100>.
302
303	Under normal circumstances you don't need to call this function.
304		1083
305	=back	1084	=back
306		1085
307	=cut	1086	=cut
308		1087
309	# support function to convert a fd into a perl filehandle	1088	# support function to convert a fd into a perl filehandle
310	sub _fd2fh {	1089	sub _fd2fh {
311	return undef if $_[0] < 0;	1090	return undef if $_[0] < 0;
312		1091
313	# try to be perl5.6-compatible	1092	# try to generate nice filehandles
314	local *AIO_FH;	1093	my $sym = "IO::AIO::fd#$_[0]";
315	open AIO_FH, "+<&=$_[0]"	1094	local *$sym;
		1095
		1096	open *$sym, "+<&=$_[0]" # usually works under any unix
		1097	or open *$sym, "<&=$_[0]" # cygwin needs this
		1098	or open *$sym, ">&=$_[0]" # or this
316	or return undef;	1099	or return undef;
317		1100
318	*AIO_FH	1101	*$sym
319	}	1102	}
320		1103
321	min_parallel 4;	1104	min_parallel 8;
322		1105
323	END {	1106	END {
324	max_parallel 0;	1107	min_parallel 1;
325	}	1108	flush;
		1109	};
326		1110
327	1;	1111	1;
328		1112
		1113	=head2 FORK BEHAVIOUR
		1114
		1115	This module should do "the right thing" when the process using it forks:
		1116
		1117	Before the fork, IO::AIO enters a quiescent state where no requests
		1118	can be added in other threads and no results will be processed. After
		1119	the fork the parent simply leaves the quiescent state and continues
		1120	request/result processing, while the child frees the request/result queue
		1121	(so that the requests started before the fork will only be handled in the
		1122	parent). Threads will be started on demand until the limit set in the
		1123	parent process has been reached again.
		1124
		1125	In short: the parent will, after a short pause, continue as if fork had
		1126	not been called, while the child will act as if IO::AIO has not been used
		1127	yet.
		1128
		1129	=head2 MEMORY USAGE
		1130
		1131	Per-request usage:
		1132
		1133	Each aio request uses - depending on your architecture - around 100-200
		1134	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1135	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1136	scalars and other data passed into aio requests will also be locked and
		1137	will consume memory till the request has entered the done state.
		1138
		1139	This is now awfully much, so queuing lots of requests is not usually a
		1140	problem.
		1141
		1142	Per-thread usage:
		1143
		1144	In the execution phase, some aio requests require more memory for
		1145	temporary buffers, and each thread requires a stack and other data
		1146	structures (usually around 16k-128k, depending on the OS).
		1147
		1148	=head1 KNOWN BUGS
		1149
		1150	Known bugs will be fixed in the next release.
		1151
329	=head1 SEE ALSO	1152	=head1 SEE ALSO
330		1153
331	L<Coro>, L<Linux::AIO>.	1154	L<Coro::AIO>.
332		1155
333	=head1 AUTHOR	1156	=head1 AUTHOR
334		1157
335	Marc Lehmann <schmorp@schmorp.de>	1158	Marc Lehmann <schmorp@schmorp.de>
336	http://home.schmorp.de/	1159	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.21 by root, Wed Jul 13 00:13:09 2005 UTC vs. Revision 1.89 by root, Sun Oct 29 11:03:18 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.21 by root, Wed Jul 13 00:13:09 2005 UTC vs.
Revision 1.89 by root, Sun Oct 29 11:03:18 2006 UTC