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Revision 1.59 by root, Sun Oct 22 10:33:26 2006 UTC vs.
Revision 1.169 by root, Sat Jan 2 13:02:20 2010 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
…		…
18	};	19	};
19		20
20	# version 2+ has request and group objects	21	# version 2+ has request and group objects
21	use IO::AIO 2;	22	use IO::AIO 2;
22		23
		24	aioreq_pri 4; # give next request a very high priority
23	my $req = aio_unlink "/tmp/file", sub { };	25	my $req = aio_unlink "/tmp/file", sub { };
24	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
25		27
26	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
28		30
		31	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		32	use AnyEvent::AIO;
		33
29	# AnyEvent integration	34	# EV integration
30	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	35	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
31	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
32		36
33	# Event integration	37	# Event integration
34	Event->io (fd => IO::AIO::poll_fileno,	38	Event->io (fd => IO::AIO::poll_fileno,
35	poll => 'r',	39	poll => 'r',
36	cb => \&IO::AIO::poll_cb);	40	cb => \&IO::AIO::poll_cb);
…		…
48	\&IO::AIO::poll_cb);	52	\&IO::AIO::poll_cb);
49		53
50	=head1 DESCRIPTION	54	=head1 DESCRIPTION
51		55
52	This module implements asynchronous I/O using whatever means your	56	This module implements asynchronous I/O using whatever means your
53	operating system supports.	57	operating system supports. It is implemented as an interface to C<libeio>
		58	(L<http://software.schmorp.de/pkg/libeio.html>).
54		59
		60	Asynchronous means that operations that can normally block your program
		61	(e.g. reading from disk) will be done asynchronously: the operation
		62	will still block, but you can do something else in the meantime. This
		63	is extremely useful for programs that need to stay interactive even
		64	when doing heavy I/O (GUI programs, high performance network servers
		65	etc.), but can also be used to easily do operations in parallel that are
		66	normally done sequentially, e.g. stat'ing many files, which is much faster
		67	on a RAID volume or over NFS when you do a number of stat operations
		68	concurrently.
		69
		70	While most of this works on all types of file descriptors (for
		71	example sockets), using these functions on file descriptors that
		72	support nonblocking operation (again, sockets, pipes etc.) is
		73	very inefficient. Use an event loop for that (such as the L<EV>
		74	module): IO::AIO will naturally fit into such an event loop itself.
		75
55	Currently, a number of threads are started that execute your read/writes	76	In this version, a number of threads are started that execute your
56	and signal their completion. You don't need thread support in your libc or	77	requests and signal their completion. You don't need thread support
57	perl, and the threads created by this module will not be visible to the	78	in perl, and the threads created by this module will not be visible
58	pthreads library. In the future, this module might make use of the native	79	to perl. In the future, this module might make use of the native aio
59	aio functions available on many operating systems. However, they are often	80	functions available on many operating systems. However, they are often
60	not well-supported (Linux doesn't allow them on normal files currently,	81	not well-supported or restricted (GNU/Linux doesn't allow them on normal
61	for example), and they would only support aio_read and aio_write, so the	82	files currently, for example), and they would only support aio_read and
62	remaining functionality would have to be implemented using threads anyway.	83	aio_write, so the remaining functionality would have to be implemented
		84	using threads anyway.
63		85
64	Although the module will work with in the presence of other threads, it is	86	Although the module will work in the presence of other (Perl-) threads,
65	currently not reentrant, so use appropriate locking yourself, always call	87	it is currently not reentrant in any way, so use appropriate locking
66	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	88	yourself, always call C<poll_cb> from within the same thread, or never
67	C<aio_> functions) recursively.	89	call C<poll_cb> (or other C<aio_> functions) recursively.
		90
		91	=head2 EXAMPLE
		92
		93	This is a simple example that uses the EV module and loads
		94	F</etc/passwd> asynchronously:
		95
		96	use Fcntl;
		97	use EV;
		98	use IO::AIO;
		99
		100	# register the IO::AIO callback with EV
		101	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&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	EV::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	EV::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
68		184
69	=cut	185	=cut
70		186
71	package IO::AIO;	187	package IO::AIO;
72		188
73	no warnings;	189	use Carp ();
74	use strict 'vars';	190
		191	use common::sense;
75		192
76	use base 'Exporter';	193	use base 'Exporter';
77		194
78	BEGIN {	195	BEGIN {
79	our $VERSION = '2.0';	196	our $VERSION = '3.31';
80		197
81	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	198	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
82	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	199	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
83	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	200	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
84	aio_group);	201	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
85	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	202	aio_rename aio_link aio_move aio_copy aio_group
		203	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		204	aio_chmod aio_utime aio_truncate);
		205
		206	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		207	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		208	min_parallel max_parallel max_idle
		209	nreqs nready npending nthreads
		210	max_poll_time max_poll_reqs
		211	sendfile fadvise);
		212
		213	push @AIO_REQ, qw(aio_busy); # not exported
86		214
87	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	215	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
88		216
89	require XSLoader;	217	require XSLoader;
90	XSLoader::load ("IO::AIO", $VERSION);	218	XSLoader::load ("IO::AIO", $VERSION);
91	}	219	}
92		220
93	=head1 FUNCTIONS	221	=head1 FUNCTIONS
94		222
95	=head2 AIO FUNCTIONS	223	=head2 AIO REQUEST FUNCTIONS
96		224
97	All the C<aio_*> calls are more or less thin wrappers around the syscall	225	All the C<aio_*> calls are more or less thin wrappers around the syscall
98	with the same name (sans C<aio_>). The arguments are similar or identical,	226	with the same name (sans C<aio_>). The arguments are similar or identical,
99	and they all accept an additional (and optional) C<$callback> argument	227	and they all accept an additional (and optional) C<$callback> argument
100	which must be a code reference. This code reference will get called with	228	which must be a code reference. This code reference will get called with
101	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	229	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
102	perl, which usually delivers "false") as it's sole argument when the given	230	perl, which usually delivers "false") as its sole argument after the given
103	syscall has been executed asynchronously.	231	syscall has been executed asynchronously.
104		232
105	All functions expecting a filehandle keep a copy of the filehandle	233	All functions expecting a filehandle keep a copy of the filehandle
106	internally until the request has finished.	234	internally until the request has finished.
107		235
108	All requests return objects of type L<IO::AIO::REQ> that allow further	236	All functions return request objects of type L<IO::AIO::REQ> that allow
109	manipulation of those requests while they are in-flight.	237	further manipulation of those requests while they are in-flight.
110		238
111	The pathnames you pass to these routines I<must> be absolute and	239	The pathnames you pass to these routines I<must> be absolute and
112	encoded in byte form. The reason for the former is that at the time the	240	encoded as octets. The reason for the former is that at the time the
113	request is being executed, the current working directory could have	241	request is being executed, the current working directory could have
114	changed. Alternatively, you can make sure that you never change the	242	changed. Alternatively, you can make sure that you never change the
115	current working directory.	243	current working directory anywhere in the program and then use relative
		244	paths.
116		245
117	To encode pathnames to byte form, either make sure you either: a)	246	To encode pathnames as octets, either make sure you either: a) always pass
118	always pass in filenames you got from outside (command line, readdir	247	in filenames you got from outside (command line, readdir etc.) without
119	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	248	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
120	your pathnames to the locale (or other) encoding in effect in the user	249	your pathnames to the locale (or other) encoding in effect in the user
121	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	250	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
122	use something else.	251	use something else to ensure your scalar has the correct contents.
		252
		253	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		254	handles correctly whether it is set or not.
123		255
124	=over 4	256	=over 4
		257
		258	=item $prev_pri = aioreq_pri [$pri]
		259
		260	Returns the priority value that would be used for the next request and, if
		261	C<$pri> is given, sets the priority for the next aio request.
		262
		263	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		264	and C<4>, respectively. Requests with higher priority will be serviced
		265	first.
		266
		267	The priority will be reset to C<0> after each call to one of the C<aio_*>
		268	functions.
		269
		270	Example: open a file with low priority, then read something from it with
		271	higher priority so the read request is serviced before other low priority
		272	open requests (potentially spamming the cache):
		273
		274	aioreq_pri -3;
		275	aio_open ..., sub {
		276	return unless $_[0];
		277
		278	aioreq_pri -2;
		279	aio_read $_[0], ..., sub {
		280	...
		281	};
		282	};
		283
		284
		285	=item aioreq_nice $pri_adjust
		286
		287	Similar to C<aioreq_pri>, but subtracts the given value from the current
		288	priority, so the effect is cumulative.
		289
125		290
126	=item aio_open $pathname, $flags, $mode, $callback->($fh)	291	=item aio_open $pathname, $flags, $mode, $callback->($fh)
127		292
128	Asynchronously open or create a file and call the callback with a newly	293	Asynchronously open or create a file and call the callback with a newly
129	created filehandle for the file.	294	created filehandle for the file.
…		…
135	list. They are the same as used by C<sysopen>.	300	list. They are the same as used by C<sysopen>.
136		301
137	Likewise, C<$mode> specifies the mode of the newly created file, if it	302	Likewise, C<$mode> specifies the mode of the newly created file, if it
138	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	303	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
139	except that it is mandatory (i.e. use C<0> if you don't create new files,	304	except that it is mandatory (i.e. use C<0> if you don't create new files,
140	and C<0666> or C<0777> if you do).	305	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		306	by the umask in effect then the request is being executed, so better never
		307	change the umask.
141		308
142	Example:	309	Example:
143		310
144	aio_open "/etc/passwd", O_RDONLY, 0, sub {	311	aio_open "/etc/passwd", O_RDONLY, 0, sub {
145	if ($_[0]) {	312	if ($_[0]) {
…		…
148	} else {	315	} else {
149	die "open failed: $!\n";	316	die "open failed: $!\n";
150	}	317	}
151	};	318	};
152		319
		320
153	=item aio_close $fh, $callback->($status)	321	=item aio_close $fh, $callback->($status)
154		322
155	Asynchronously close a file and call the callback with the result	323	Asynchronously close a file and call the callback with the result
156	code. I<WARNING:> although accepted, you should not pass in a perl	324	code.
157	filehandle here, as perl will likely close the file descriptor another
158	time when the filehandle is destroyed. Normally, you can safely call perls
159	C<close> or just let filehandles go out of scope.
160		325
161	This is supposed to be a bug in the API, so that might change. It's	326	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
162	therefore best to avoid this function.	327	closing the file descriptor associated with the filehandle itself.
		328
		329	Therefore, C<aio_close> will not close the filehandle - instead it will
		330	use dup2 to overwrite the file descriptor with the write-end of a pipe
		331	(the pipe fd will be created on demand and will be cached).
		332
		333	Or in other words: the file descriptor will be closed, but it will not be
		334	free for reuse until the perl filehandle is closed.
		335
		336	=cut
163		337
164	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	338	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
165		339
166	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	340	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
167		341
168	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	342	Reads or writes C<$length> bytes from or to the specified C<$fh> and
169	into the scalar given by C<data> and offset C<dataoffset> and calls the	343	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
170	callback without the actual number of bytes read (or -1 on error, just	344	and calls the callback without the actual number of bytes read (or -1 on
171	like the syscall).	345	error, just like the syscall).
		346
		347	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		348	offset plus the actual number of bytes read.
		349
		350	If C<$offset> is undefined, then the current file descriptor offset will
		351	be used (and updated), otherwise the file descriptor offset will not be
		352	changed by these calls.
		353
		354	If C<$length> is undefined in C<aio_write>, use the remaining length of
		355	C<$data>.
		356
		357	If C<$dataoffset> is less than zero, it will be counted from the end of
		358	C<$data>.
172		359
173	The C<$data> scalar I<MUST NOT> be modified in any way while the request	360	The C<$data> scalar I<MUST NOT> be modified in any way while the request
174	is outstanding. Modifying it can result in segfaults or WW3 (if the	361	is outstanding. Modifying it can result in segfaults or World War III (if
175	necessary/optional hardware is installed).	362	the necessary/optional hardware is installed).
176		363
177	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	364	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
178	offset C<0> within the scalar:	365	offset C<0> within the scalar:
179		366
180	aio_read $fh, 7, 15, $buffer, 0, sub {	367	aio_read $fh, 7, 15, $buffer, 0, sub {
181	$_[0] > 0 or die "read error: $!";	368	$_[0] > 0 or die "read error: $!";
182	print "read $_[0] bytes: <$buffer>\n";	369	print "read $_[0] bytes: <$buffer>\n";
183	};	370	};
184		371
185	=item aio_move $srcpath, $dstpath, $callback->($status)
186
187	[EXPERIMENTAL due to internal aio_group use]
188
189	Try to move the I<file> (directories not supported as either source or
190	destination) from C<$srcpath> to C<$dstpath> and call the callback with
191	the C<0> (error) or C<-1> ok.
192
193	This is a composite request that tries to rename(2) the file first. If
194	rename files with C<EXDEV>, it creates the destination file with mode 0200
195	and copies the contents of the source file into it using C<aio_sendfile>,
196	followed by restoring atime, mtime, access mode and uid/gid, in that
197	order, and unlinking the C<$srcpath>.
198
199	If an error occurs, the partial destination file will be unlinked, if
200	possible, except when setting atime, mtime, access mode and uid/gid, where
201	errors are being ignored.
202
203	=cut
204
205	sub aio_move($$$) {
206	my ($src, $dst, $cb) = @_;
207
208	my $grp = aio_group $cb;
209
210	add $grp aio_rename $src, $dst, sub {
211	if ($_[0] && $! == EXDEV) {
212	add $grp aio_open $src, O_RDONLY, 0, sub {
213	if (my $src_fh = $_[0]) {
214	my @stat = stat $src_fh;
215
216	add $grp aio_open $dst, O_WRONLY, 0200, sub {
217	if (my $dst_fh = $_[0]) {
218	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
219	close $src_fh;
220
221	if ($_[0] == $stat[7]) {
222	utime $stat[8], $stat[9], $dst;
223	chmod $stat[2] & 07777, $dst_fh;
224	chown $stat[4], $stat[5], $dst_fh;
225	close $dst_fh;
226
227	add $grp aio_unlink $src, sub {
228	$grp->result ($_[0]);
229	};
230	} else {
231	my $errno = $!;
232	add $grp aio_unlink $dst, sub {
233	$! = $errno;
234	$grp->result (-1);
235	};
236	}
237	};
238	} else {
239	$grp->result (-1);
240	}
241	},
242
243	} else {
244	$grp->result (-1);
245	}
246	};
247	} else {
248	$grp->result ($_[0]);
249	}
250	};
251
252	$grp
253	}
254		372
255	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	373	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
256		374
257	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	375	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
258	reading at byte offset C<$in_offset>, and starts writing at the current	376	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
262		380
263	This call tries to make use of a native C<sendfile> syscall to provide	381	This call tries to make use of a native C<sendfile> syscall to provide
264	zero-copy operation. For this to work, C<$out_fh> should refer to a	382	zero-copy operation. For this to work, C<$out_fh> should refer to a
265	socket, and C<$in_fh> should refer to mmap'able file.	383	socket, and C<$in_fh> should refer to mmap'able file.
266		384
267	If the native sendfile call fails or is not implemented, it will be	385	If the native sendfile call fails with C<ENOSYS>, C<ENOTSUP>,
		386	C<EOPNOTSUPP> or C<ENOTSOCK>, or is not implemented, it will be emulated,
268	emulated, so you can call C<aio_sendfile> on any type of filehandle	387	so you can call C<aio_sendfile> on any type of filehandle regardless of
269	regardless of the limitations of the operating system.	388	the limitations of the operating system.
270		389
271	Please note, however, that C<aio_sendfile> can read more bytes from	390	Please note, however, that C<aio_sendfile> can read more bytes from
272	C<$in_fh> than are written, and there is no way to find out how many	391	C<$in_fh> than are written, and there is no way to find out how many
273	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	392	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
274	provides the number of bytes written to C<$out_fh>. Only if the result	393	provides the number of bytes written to C<$out_fh>. Only if the result
275	value equals C<$length> one can assume that C<$length> bytes have been	394	value equals C<$length> one can assume that C<$length> bytes have been
276	read.	395	read.
		396
277		397
278	=item aio_readahead $fh,$offset,$length, $callback->($retval)	398	=item aio_readahead $fh,$offset,$length, $callback->($retval)
279		399
280	C<aio_readahead> populates the page cache with data from a file so that	400	C<aio_readahead> populates the page cache with data from a file so that
281	subsequent reads from that file will not block on disk I/O. The C<$offset>	401	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
287	file. The current file offset of the file is left unchanged.	407	file. The current file offset of the file is left unchanged.
288		408
289	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	409	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
290	emulated by simply reading the data, which would have a similar effect.	410	emulated by simply reading the data, which would have a similar effect.
291		411
		412
292	=item aio_stat $fh_or_path, $callback->($status)	413	=item aio_stat $fh_or_path, $callback->($status)
293		414
294	=item aio_lstat $fh, $callback->($status)	415	=item aio_lstat $fh, $callback->($status)
295		416
296	Works like perl's C<stat> or C<lstat> in void context. The callback will	417	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
309	aio_stat "/etc/passwd", sub {	430	aio_stat "/etc/passwd", sub {
310	$_[0] and die "stat failed: $!";	431	$_[0] and die "stat failed: $!";
311	print "size is ", -s _, "\n";	432	print "size is ", -s _, "\n";
312	};	433	};
313		434
		435
		436	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		437
		438	Works like perl's C<utime> function (including the special case of $atime
		439	and $mtime being undef). Fractional times are supported if the underlying
		440	syscalls support them.
		441
		442	When called with a pathname, uses utimes(2) if available, otherwise
		443	utime(2). If called on a file descriptor, uses futimes(2) if available,
		444	otherwise returns ENOSYS, so this is not portable.
		445
		446	Examples:
		447
		448	# set atime and mtime to current time (basically touch(1)):
		449	aio_utime "path", undef, undef;
		450	# set atime to current time and mtime to beginning of the epoch:
		451	aio_utime "path", time, undef; # undef==0
		452
		453
		454	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		455
		456	Works like perl's C<chown> function, except that C<undef> for either $uid
		457	or $gid is being interpreted as "do not change" (but -1 can also be used).
		458
		459	Examples:
		460
		461	# same as "chown root path" in the shell:
		462	aio_chown "path", 0, -1;
		463	# same as above:
		464	aio_chown "path", 0, undef;
		465
		466
		467	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		468
		469	Works like truncate(2) or ftruncate(2).
		470
		471
		472	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		473
		474	Works like perl's C<chmod> function.
		475
		476
314	=item aio_unlink $pathname, $callback->($status)	477	=item aio_unlink $pathname, $callback->($status)
315		478
316	Asynchronously unlink (delete) a file and call the callback with the	479	Asynchronously unlink (delete) a file and call the callback with the
317	result code.	480	result code.
318		481
		482
		483	=item aio_mknod $path, $mode, $dev, $callback->($status)
		484
		485	[EXPERIMENTAL]
		486
		487	Asynchronously create a device node (or fifo). See mknod(2).
		488
		489	The only (POSIX-) portable way of calling this function is:
		490
		491	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		492
		493
319	=item aio_link $srcpath, $dstpath, $callback->($status)	494	=item aio_link $srcpath, $dstpath, $callback->($status)
320		495
321	Asynchronously create a new link to the existing object at C<$srcpath> at	496	Asynchronously create a new link to the existing object at C<$srcpath> at
322	the path C<$dstpath> and call the callback with the result code.	497	the path C<$dstpath> and call the callback with the result code.
323		498
		499
324	=item aio_symlink $srcpath, $dstpath, $callback->($status)	500	=item aio_symlink $srcpath, $dstpath, $callback->($status)
325		501
326	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	502	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
327	the path C<$dstpath> and call the callback with the result code.	503	the path C<$dstpath> and call the callback with the result code.
328		504
		505
		506	=item aio_readlink $path, $callback->($link)
		507
		508	Asynchronously read the symlink specified by C<$path> and pass it to
		509	the callback. If an error occurs, nothing or undef gets passed to the
		510	callback.
		511
		512
329	=item aio_rename $srcpath, $dstpath, $callback->($status)	513	=item aio_rename $srcpath, $dstpath, $callback->($status)
330		514
331	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	515	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
332	rename(2) and call the callback with the result code.	516	rename(2) and call the callback with the result code.
333		517
		518
		519	=item aio_mkdir $pathname, $mode, $callback->($status)
		520
		521	Asynchronously mkdir (create) a directory and call the callback with
		522	the result code. C<$mode> will be modified by the umask at the time the
		523	request is executed, so do not change your umask.
		524
		525
334	=item aio_rmdir $pathname, $callback->($status)	526	=item aio_rmdir $pathname, $callback->($status)
335		527
336	Asynchronously rmdir (delete) a directory and call the callback with the	528	Asynchronously rmdir (delete) a directory and call the callback with the
337	result code.	529	result code.
		530
338		531
339	=item aio_readdir $pathname, $callback->($entries)	532	=item aio_readdir $pathname, $callback->($entries)
340		533
341	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	534	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
342	directory (i.e. opendir + readdir + closedir). The entries will not be	535	directory (i.e. opendir + readdir + closedir). The entries will not be
343	sorted, and will B<NOT> include the C<.> and C<..> entries.	536	sorted, and will B<NOT> include the C<.> and C<..> entries.
344		537
345	The callback a single argument which is either C<undef> or an array-ref	538	The callback is passed a single argument which is either C<undef> or an
346	with the filenames.	539	array-ref with the filenames.
		540
		541
		542	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		543
		544	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		545	behaviour and output format. In case of an error, C<$entries> will be
		546	C<undef>.
		547
		548	The flags are a combination of the following constants, ORed together (the
		549	flags will also be passed to the callback, possibly modified):
		550
		551	=over 4
		552
		553	=item IO::AIO::READDIR_DENTS
		554
		555	When this flag is off, then the callback gets an arrayref with of names
		556	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		557	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		558	entry in more detail.
		559
		560	C<$name> is the name of the entry.
		561
		562	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		563
		564	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		565	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		566	C<IO::AIO::DT_WHT>.
		567
		568	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		569	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		570	scalars are read-only: you can not modify them.
		571
		572	C<$inode> is the inode number (which might not be exact on systems with 64
		573	bit inode numbers and 32 bit perls). This field has unspecified content on
		574	systems that do not deliver the inode information.
		575
		576	=item IO::AIO::READDIR_DIRS_FIRST
		577
		578	When this flag is set, then the names will be returned in an order where
		579	likely directories come first. This is useful when you need to quickly
		580	find directories, or you want to find all directories while avoiding to
		581	stat() each entry.
		582
		583	If the system returns type information in readdir, then this is used
		584	to find directories directly. Otherwise, likely directories are files
		585	beginning with ".", or otherwise files with no dots, of which files with
		586	short names are tried first.
		587
		588	=item IO::AIO::READDIR_STAT_ORDER
		589
		590	When this flag is set, then the names will be returned in an order
		591	suitable for stat()'ing each one. That is, when you plan to stat()
		592	all files in the given directory, then the returned order will likely
		593	be fastest.
		594
		595	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		596	the likely dirs come first, resulting in a less optimal stat order.
		597
		598	=item IO::AIO::READDIR_FOUND_UNKNOWN
		599
		600	This flag should not be set when calling C<aio_readdirx>. Instead, it
		601	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		602	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		603	C<$type>'s are known, which can be used to speed up some algorithms.
		604
		605	=back
		606
		607
		608	=item aio_load $path, $data, $callback->($status)
		609
		610	This is a composite request that tries to fully load the given file into
		611	memory. Status is the same as with aio_read.
		612
		613	=cut
		614
		615	sub aio_load($$;$) {
		616	my ($path, undef, $cb) = @_;
		617	my $data = \$_[1];
		618
		619	my $pri = aioreq_pri;
		620	my $grp = aio_group $cb;
		621
		622	aioreq_pri $pri;
		623	add $grp aio_open $path, O_RDONLY, 0, sub {
		624	my $fh = shift
		625	or return $grp->result (-1);
		626
		627	aioreq_pri $pri;
		628	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		629	$grp->result ($_[0]);
		630	};
		631	};
		632
		633	$grp
		634	}
		635
		636	=item aio_copy $srcpath, $dstpath, $callback->($status)
		637
		638	Try to copy the I<file> (directories not supported as either source or
		639	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		640	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		641
		642	This is a composite request that creates the destination file with
		643	mode 0200 and copies the contents of the source file into it using
		644	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		645	uid/gid, in that order.
		646
		647	If an error occurs, the partial destination file will be unlinked, if
		648	possible, except when setting atime, mtime, access mode and uid/gid, where
		649	errors are being ignored.
		650
		651	=cut
		652
		653	sub aio_copy($$;$) {
		654	my ($src, $dst, $cb) = @_;
		655
		656	my $pri = aioreq_pri;
		657	my $grp = aio_group $cb;
		658
		659	aioreq_pri $pri;
		660	add $grp aio_open $src, O_RDONLY, 0, sub {
		661	if (my $src_fh = $_[0]) {
		662	my @stat = stat $src_fh; # hmm, might block over nfs?
		663
		664	aioreq_pri $pri;
		665	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		666	if (my $dst_fh = $_[0]) {
		667	aioreq_pri $pri;
		668	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		669	if ($_[0] == $stat[7]) {
		670	$grp->result (0);
		671	close $src_fh;
		672
		673	my $ch = sub {
		674	aioreq_pri $pri;
		675	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		676	aioreq_pri $pri;
		677	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		678	aioreq_pri $pri;
		679	add $grp aio_close $dst_fh;
		680	}
		681	};
		682	};
		683
		684	aioreq_pri $pri;
		685	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		686	if ($_[0] < 0 && $! == ENOSYS) {
		687	aioreq_pri $pri;
		688	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		689	} else {
		690	$ch->();
		691	}
		692	};
		693	} else {
		694	$grp->result (-1);
		695	close $src_fh;
		696	close $dst_fh;
		697
		698	aioreq $pri;
		699	add $grp aio_unlink $dst;
		700	}
		701	};
		702	} else {
		703	$grp->result (-1);
		704	}
		705	},
		706
		707	} else {
		708	$grp->result (-1);
		709	}
		710	};
		711
		712	$grp
		713	}
		714
		715	=item aio_move $srcpath, $dstpath, $callback->($status)
		716
		717	Try to move the I<file> (directories not supported as either source or
		718	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		719	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		720
		721	This is a composite request that tries to rename(2) the file first; if
		722	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		723	that is successful, unlinks the C<$srcpath>.
		724
		725	=cut
		726
		727	sub aio_move($$;$) {
		728	my ($src, $dst, $cb) = @_;
		729
		730	my $pri = aioreq_pri;
		731	my $grp = aio_group $cb;
		732
		733	aioreq_pri $pri;
		734	add $grp aio_rename $src, $dst, sub {
		735	if ($_[0] && $! == EXDEV) {
		736	aioreq_pri $pri;
		737	add $grp aio_copy $src, $dst, sub {
		738	$grp->result ($_[0]);
		739
		740	if (!$_[0]) {
		741	aioreq_pri $pri;
		742	add $grp aio_unlink $src;
		743	}
		744	};
		745	} else {
		746	$grp->result ($_[0]);
		747	}
		748	};
		749
		750	$grp
		751	}
347		752
348	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	753	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
349		754
350	[EXPERIMENTAL due to internal aio_group use]
351
352	Scans a directory (similar to C<aio_readdir>) but additionally tries to	755	Scans a directory (similar to C<aio_readdir>) but additionally tries to
353	separate the entries of directory C<$path> into two sets of names, ones	756	efficiently separate the entries of directory C<$path> into two sets of
354	you can recurse into (directories or links to them), and ones you cannot	757	names, directories you can recurse into (directories), and ones you cannot
355	recurse into (everything else).	758	recurse into (everything else, including symlinks to directories).
356		759
357	C<aio_scandir> is a composite request that consists of many sub	760	C<aio_scandir> is a composite request that creates of many sub requests_
358	requests. C<$maxreq> specifies the maximum number of outstanding aio	761	C<$maxreq> specifies the maximum number of outstanding aio requests that
359	requests that this function generates. If it is C<< <= 0 >>, then a	762	this function generates. If it is C<< <= 0 >>, then a suitable default
360	suitable default will be chosen (currently 8).	763	will be chosen (currently 4).
361		764
362	On error, the callback is called without arguments, otherwise it receives	765	On error, the callback is called without arguments, otherwise it receives
363	two array-refs with path-relative entry names.	766	two array-refs with path-relative entry names.
364		767
365	Example:	768	Example:
…		…
372		775
373	Implementation notes.	776	Implementation notes.
374		777
375	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	778	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
376		779
		780	If readdir returns file type information, then this is used directly to
		781	find directories.
		782
377	After reading the directory, the modification time, size etc. of the	783	Otherwise, after reading the directory, the modification time, size etc.
378	directory before and after the readdir is checked, and if they match (and	784	of the directory before and after the readdir is checked, and if they
379	isn't the current time), the link count will be used to decide how many	785	match (and isn't the current time), the link count will be used to decide
380	entries are directories (if >= 2). Otherwise, no knowledge of the number	786	how many entries are directories (if >= 2). Otherwise, no knowledge of the
381	of subdirectories will be assumed.	787	number of subdirectories will be assumed.
382		788
383	Then entries will be sorted into likely directories (everything without	789	Then entries will be sorted into likely directories a non-initial dot
384	a non-initial dot currently) and likely non-directories (everything	790	currently) and likely non-directories (see C<aio_readdirx>). Then every
385	else). Then every entry plus an appended C</.> will be C<stat>'ed,	791	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
386	likely directories first. If that succeeds, it assumes that the entry	792	in order of their inode numbers. If that succeeds, it assumes that the
387	is a directory or a symlink to directory (which will be checked	793	entry is a directory or a symlink to directory (which will be checked
388	seperately). This is often faster than stat'ing the entry itself because	794	seperately). This is often faster than stat'ing the entry itself because
389	filesystems might detect the type of the entry without reading the inode	795	filesystems might detect the type of the entry without reading the inode
390	data (e.g. ext2fs filetype feature).	796	data (e.g. ext2fs filetype feature), even on systems that cannot return
		797	the filetype information on readdir.
391		798
392	If the known number of directories (link count - 2) has been reached, the	799	If the known number of directories (link count - 2) has been reached, the
393	rest of the entries is assumed to be non-directories.	800	rest of the entries is assumed to be non-directories.
394		801
395	This only works with certainty on POSIX (= UNIX) filesystems, which	802	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
399	as those tend to return 0 or 1 as link counts, which disables the	806	as those tend to return 0 or 1 as link counts, which disables the
400	directory counting heuristic.	807	directory counting heuristic.
401		808
402	=cut	809	=cut
403		810
404	sub aio_scandir($$$) {	811	sub aio_scandir($$;$) {
405	my ($path, $maxreq, $cb) = @_;	812	my ($path, $maxreq, $cb) = @_;
406		813
		814	my $pri = aioreq_pri;
		815
407	my $grp = aio_group $cb;	816	my $grp = aio_group $cb;
408		817
409	$maxreq = 8 if $maxreq <= 0;	818	$maxreq = 4 if $maxreq <= 0;
410		819
411	# stat once	820	# stat once
		821	aioreq_pri $pri;
412	add $grp aio_stat $path, sub {	822	add $grp aio_stat $path, sub {
413	return $grp->result () if $_[0];	823	return $grp->result () if $_[0];
414	my $now = time;	824	my $now = time;
415	my $hash1 = join ":", (stat _)[0,1,3,7,9];	825	my $hash1 = join ":", (stat _)[0,1,3,7,9];
416		826
417	# read the directory entries	827	# read the directory entries
		828	aioreq_pri $pri;
418	add $grp aio_readdir $path, sub {	829	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
419	my $entries = shift	830	my $entries = shift
420	or return $grp->result ();	831	or return $grp->result ();
421		832
422	# stat the dir another time	833	# stat the dir another time
		834	aioreq_pri $pri;
423	add $grp aio_stat $path, sub {	835	add $grp aio_stat $path, sub {
424	my $hash2 = join ":", (stat _)[0,1,3,7,9];	836	my $hash2 = join ":", (stat _)[0,1,3,7,9];
425		837
426	my $ndirs;	838	my $ndirs;
427		839
428	# take the slow route if anything looks fishy	840	# take the slow route if anything looks fishy
429	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	841	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
430	$ndirs = -1;	842	$ndirs = -1;
431	} else {	843	} else {
432	# if nlink == 2, we are finished	844	# if nlink == 2, we are finished
433	# on non-posix-fs's, we rely on nlink < 2	845	# for non-posix-fs's, we rely on nlink < 2
434	$ndirs = (stat _)[3] - 2	846	$ndirs = (stat _)[3] - 2
435	or return $grp->result ([], $entries);	847	or return $grp->result ([], $entries);
436	}	848	}
437		849
438	# sort into likely dirs and likely nondirs
439	# dirs == files without ".", short entries first
440	$entries = [map $_->[0],
441	sort { $b->[1] cmp $a->[1] }
442	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
443	@$entries];
444
445	my (@dirs, @nondirs);	850	my (@dirs, @nondirs);
446		851
447	my ($statcb, $schedcb);	852	my $statgrp = add $grp aio_group sub {
448	my $nreq = 0;	853	$grp->result (\@dirs, \@nondirs);
		854	};
449		855
450	$schedcb = sub {	856	limit $statgrp $maxreq;
451	if (@$entries) {	857	feed $statgrp sub {
452	if ($nreq < $maxreq) {	858	return unless @$entries;
453	my $ent = pop @$entries;	859	my $entry = shift @$entries;
		860
		861	aioreq_pri $pri;
		862	add $statgrp aio_stat "$path/$entry/.", sub {
		863	if ($_[0] < 0) {
		864	push @nondirs, $entry;
		865	} else {
		866	# need to check for real directory
		867	aioreq_pri $pri;
		868	add $statgrp aio_lstat "$path/$entry", sub {
		869	if (-d _) {
		870	push @dirs, $entry;
		871
		872	unless (--$ndirs) {
		873	push @nondirs, @$entries;
		874	feed $statgrp;
		875	}
		876	} else {
		877	push @nondirs, $entry;
		878	}
454	$nreq++;	879	}
455	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
456	}	880	}
457	} elsif (!$nreq) {
458	# finished
459	undef $statcb;
460	undef $schedcb;
461	$grp->result (\@dirs, \@nondirs) if $cb;
462	undef $cb;
463	}	881	};
464	};	882	};
465	$statcb = sub {
466	my ($status, $entry) = @_;
467
468	if ($status < 0) {
469	$nreq--;
470	push @nondirs, $entry;
471	&$schedcb;
472	} else {
473	# need to check for real directory
474	add $grp aio_lstat "$path/$entry", sub {
475	$nreq--;
476
477	if (-d _) {
478	push @dirs, $entry;
479
480	if (!--$ndirs) {
481	push @nondirs, @$entries;
482	$entries = [];
483	}
484	} else {
485	push @nondirs, $entry;
486	}
487
488	&$schedcb;
489	}
490	}
491	};
492
493	&$schedcb while @$entries && $nreq < $maxreq;
494	};	883	};
495	};	884	};
496	};	885	};
497		886
498	$grp	887	$grp
499	}	888	}
500		889
		890	=item aio_rmtree $path, $callback->($status)
		891
		892	Delete a directory tree starting (and including) C<$path>, return the
		893	status of the final C<rmdir> only. This is a composite request that
		894	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		895	everything else.
		896
		897	=cut
		898
		899	sub aio_rmtree;
		900	sub aio_rmtree($;$) {
		901	my ($path, $cb) = @_;
		902
		903	my $pri = aioreq_pri;
		904	my $grp = aio_group $cb;
		905
		906	aioreq_pri $pri;
		907	add $grp aio_scandir $path, 0, sub {
		908	my ($dirs, $nondirs) = @_;
		909
		910	my $dirgrp = aio_group sub {
		911	add $grp aio_rmdir $path, sub {
		912	$grp->result ($_[0]);
		913	};
		914	};
		915
		916	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		917	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		918
		919	add $grp $dirgrp;
		920	};
		921
		922	$grp
		923	}
		924
		925	=item aio_sync $callback->($status)
		926
		927	Asynchronously call sync and call the callback when finished.
		928
501	=item aio_fsync $fh, $callback->($status)	929	=item aio_fsync $fh, $callback->($status)
502		930
503	Asynchronously call fsync on the given filehandle and call the callback	931	Asynchronously call fsync on the given filehandle and call the callback
504	with the fsync result code.	932	with the fsync result code.
505		933
…		…
509	callback with the fdatasync result code.	937	callback with the fdatasync result code.
510		938
511	If this call isn't available because your OS lacks it or it couldn't be	939	If this call isn't available because your OS lacks it or it couldn't be
512	detected, it will be emulated by calling C<fsync> instead.	940	detected, it will be emulated by calling C<fsync> instead.
513		941
		942	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		943
		944	Sync the data portion of the file specified by C<$offset> and C<$length>
		945	to disk (but NOT the metadata), by calling the Linux-specific
		946	sync_file_range call. If sync_file_range is not available or it returns
		947	ENOSYS, then fdatasync or fsync is being substituted.
		948
		949	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		950	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		951	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		952	manpage for details.
		953
		954	=item aio_pathsync $path, $callback->($status)
		955
		956	This request tries to open, fsync and close the given path. This is a
		957	composite request intended to sync directories after directory operations
		958	(E.g. rename). This might not work on all operating systems or have any
		959	specific effect, but usually it makes sure that directory changes get
		960	written to disc. It works for anything that can be opened for read-only,
		961	not just directories.
		962
		963	Future versions of this function might fall back to other methods when
		964	C<fsync> on the directory fails (such as calling C<sync>).
		965
		966	Passes C<0> when everything went ok, and C<-1> on error.
		967
		968	=cut
		969
		970	sub aio_pathsync($;$) {
		971	my ($path, $cb) = @_;
		972
		973	my $pri = aioreq_pri;
		974	my $grp = aio_group $cb;
		975
		976	aioreq_pri $pri;
		977	add $grp aio_open $path, O_RDONLY, 0, sub {
		978	my ($fh) = @_;
		979	if ($fh) {
		980	aioreq_pri $pri;
		981	add $grp aio_fsync $fh, sub {
		982	$grp->result ($_[0]);
		983
		984	aioreq_pri $pri;
		985	add $grp aio_close $fh;
		986	};
		987	} else {
		988	$grp->result (-1);
		989	}
		990	};
		991
		992	$grp
		993	}
		994
514	=item aio_group $callback->(...)	995	=item aio_group $callback->(...)
515
516	[EXPERIMENTAL]
517		996
518	This is a very special aio request: Instead of doing something, it is a	997	This is a very special aio request: Instead of doing something, it is a
519	container for other aio requests, which is useful if you want to bundle	998	container for other aio requests, which is useful if you want to bundle
520	many requests into a single, composite, request.	999	many requests into a single, composite, request with a definite callback
		1000	and the ability to cancel the whole request with its subrequests.
521		1001
522	Returns an object of class L<IO::AIO::GRP>. See its documentation below	1002	Returns an object of class L<IO::AIO::GRP>. See its documentation below
523	for more info.	1003	for more info.
524		1004
525	Example:	1005	Example:
…		…
531	add $grp	1011	add $grp
532	(aio_stat ...),	1012	(aio_stat ...),
533	(aio_stat ...),	1013	(aio_stat ...),
534	...;	1014	...;
535		1015
		1016	=item aio_nop $callback->()
		1017
		1018	This is a special request - it does nothing in itself and is only used for
		1019	side effects, such as when you want to add a dummy request to a group so
		1020	that finishing the requests in the group depends on executing the given
		1021	code.
		1022
		1023	While this request does nothing, it still goes through the execution
		1024	phase and still requires a worker thread. Thus, the callback will not
		1025	be executed immediately but only after other requests in the queue have
		1026	entered their execution phase. This can be used to measure request
		1027	latency.
		1028
536	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() *NOT EXPORTED*	1029	=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED*
537		1030
538	Mainly used for debugging and benchmarking, this aio request puts one of	1031	Mainly used for debugging and benchmarking, this aio request puts one of
539	the request workers to sleep for the given time.	1032	the request workers to sleep for the given time.
540		1033
541	While it is theoretically handy to have simple I/O scheduling requests	1034	While it is theoretically handy to have simple I/O scheduling requests
542	like sleep and file handle readable/writable, the overhead this creates	1035	like sleep and file handle readable/writable, the overhead this creates is
543	is immense, so do not use this function except to put your application	1036	immense (it blocks a thread for a long time) so do not use this function
544	under artificial I/O pressure.	1037	except to put your application under artificial I/O pressure.
545		1038
546	=back	1039	=back
547		1040
548	=head2 IO::AIO::REQ CLASS	1041	=head2 IO::AIO::REQ CLASS
549		1042
550	All non-aggregate C<aio_*> functions return an object of this class when	1043	All non-aggregate C<aio_*> functions return an object of this class when
551	called in non-void context.	1044	called in non-void context.
552		1045
553	A request always moves through the following five states in its lifetime,
554	in order: B<ready> (request has been created, but has not been executed
555	yet), B<execute> (request is currently being executed), B<pending>
556	(request has been executed but callback has not been called yet),
557	B<result> (results are being processed synchronously, includes calling the
558	callback) and B<done> (request has reached the end of its lifetime and
559	holds no resources anymore).
560
561	=over 4	1046	=over 4
562		1047
563	=item $req->cancel	1048	=item cancel $req
564		1049
565	Cancels the request, if possible. Has the effect of skipping execution	1050	Cancels the request, if possible. Has the effect of skipping execution
566	when entering the B<execute> state and skipping calling the callback when	1051	when entering the B<execute> state and skipping calling the callback when
567	entering the the B<result> state, but will leave the request otherwise	1052	entering the the B<result> state, but will leave the request otherwise
568	untouched. That means that requests that currently execute will not be	1053	untouched (with the exception of readdir). That means that requests that
569	stopped and resources held by the request will not be freed prematurely.	1054	currently execute will not be stopped and resources held by the request
		1055	will not be freed prematurely.
		1056
		1057	=item cb $req $callback->(...)
		1058
		1059	Replace (or simply set) the callback registered to the request.
570		1060
571	=back	1061	=back
572		1062
573	=head2 IO::AIO::GRP CLASS	1063	=head2 IO::AIO::GRP CLASS
574		1064
…		…
601	};	1091	};
602		1092
603	This makes it very easy to create composite requests (see the source of	1093	This makes it very easy to create composite requests (see the source of
604	C<aio_move> for an application) that work and feel like simple requests.	1094	C<aio_move> for an application) that work and feel like simple requests.
605		1095
		1096	=over 4
		1097
606	The IO::AIO::GRP objects will be cleaned up during calls to	1098	=item * The IO::AIO::GRP objects will be cleaned up during calls to
607	C<IO::AIO::poll_cb>, just like any other request.	1099	C<IO::AIO::poll_cb>, just like any other request.
608		1100
609	They can be canceled like any other request. Canceling will cancel not	1101	=item * They can be canceled like any other request. Canceling will cancel not
610	only the request itself, but also all requests it contains.	1102	only the request itself, but also all requests it contains.
611		1103
612	They can also can also be added to other IO::AIO::GRP objects.	1104	=item * They can also can also be added to other IO::AIO::GRP objects.
		1105
		1106	=item * You must not add requests to a group from within the group callback (or
		1107	any later time).
		1108
		1109	=back
613		1110
614	Their lifetime, simplified, looks like this: when they are empty, they	1111	Their lifetime, simplified, looks like this: when they are empty, they
615	will finish very quickly. If they contain only requests that are in the	1112	will finish very quickly. If they contain only requests that are in the
616	C<done> state, they will also finish. Otherwise they will continue to	1113	C<done> state, they will also finish. Otherwise they will continue to
617	exist.	1114	exist.
618		1115
619	That means after creating a group you have some time to add requests. And	1116	That means after creating a group you have some time to add requests
620	in the callbacks of those requests, you can add further requests to the	1117	(precisely before the callback has been invoked, which is only done within
621	group. And only when all those requests have finished will the the group	1118	the C<poll_cb>). And in the callbacks of those requests, you can add
622	itself finish.	1119	further requests to the group. And only when all those requests have
		1120	finished will the the group itself finish.
623		1121
624	=over 4	1122	=over 4
625		1123
		1124	=item add $grp ...
		1125
626	=item $grp->add (...)	1126	=item $grp->add (...)
627
628	=item add $grp ...
629		1127
630	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can	1128	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
631	be added, including other groups, as long as you do not create circular	1129	be added, including other groups, as long as you do not create circular
632	dependencies.	1130	dependencies.
633		1131
634	Returns all its arguments.	1132	Returns all its arguments.
635		1133
		1134	=item $grp->cancel_subs
		1135
		1136	Cancel all subrequests and clears any feeder, but not the group request
		1137	itself. Useful when you queued a lot of events but got a result early.
		1138
		1139	The group request will finish normally (you cannot add requests to the
		1140	group).
		1141
636	=item $grp->result (...)	1142	=item $grp->result (...)
637		1143
638	Set the result value(s) that will be passed to the group callback when all	1144	Set the result value(s) that will be passed to the group callback when all
639	subrequests have finished. By default, no argument will be passed.	1145	subrequests have finished and set the groups errno to the current value
		1146	of errno (just like calling C<errno> without an error number). By default,
		1147	no argument will be passed and errno is zero.
		1148
		1149	=item $grp->errno ([$errno])
		1150
		1151	Sets the group errno value to C<$errno>, or the current value of errno
		1152	when the argument is missing.
		1153
		1154	Every aio request has an associated errno value that is restored when
		1155	the callback is invoked. This method lets you change this value from its
		1156	default (0).
		1157
		1158	Calling C<result> will also set errno, so make sure you either set C<$!>
		1159	before the call to C<result>, or call c<errno> after it.
		1160
		1161	=item feed $grp $callback->($grp)
		1162
		1163	Sets a feeder/generator on this group: every group can have an attached
		1164	generator that generates requests if idle. The idea behind this is that,
		1165	although you could just queue as many requests as you want in a group,
		1166	this might starve other requests for a potentially long time. For example,
		1167	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
		1168	delaying any later requests for a long time.
		1169
		1170	To avoid this, and allow incremental generation of requests, you can
		1171	instead a group and set a feeder on it that generates those requests. The
		1172	feed callback will be called whenever there are few enough (see C<limit>,
		1173	below) requests active in the group itself and is expected to queue more
		1174	requests.
		1175
		1176	The feed callback can queue as many requests as it likes (i.e. C<add> does
		1177	not impose any limits).
		1178
		1179	If the feed does not queue more requests when called, it will be
		1180	automatically removed from the group.
		1181
		1182	If the feed limit is C<0> when this method is called, it will be set to
		1183	C<2> automatically.
		1184
		1185	Example:
		1186
		1187	# stat all files in @files, but only ever use four aio requests concurrently:
		1188
		1189	my $grp = aio_group sub { print "finished\n" };
		1190	limit $grp 4;
		1191	feed $grp sub {
		1192	my $file = pop @files
		1193	or return;
		1194
		1195	add $grp aio_stat $file, sub { ... };
		1196	};
		1197
		1198	=item limit $grp $num
		1199
		1200	Sets the feeder limit for the group: The feeder will be called whenever
		1201	the group contains less than this many requests.
		1202
		1203	Setting the limit to C<0> will pause the feeding process.
		1204
		1205	The default value for the limit is C<0>, but note that setting a feeder
		1206	automatically bumps it up to C<2>.
640		1207
641	=back	1208	=back
642		1209
643	=head2 SUPPORT FUNCTIONS	1210	=head2 SUPPORT FUNCTIONS
644		1211
		1212	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1213
645	=over 4	1214	=over 4
646		1215
647	=item $fileno = IO::AIO::poll_fileno	1216	=item $fileno = IO::AIO::poll_fileno
648		1217
649	Return the I<request result pipe file descriptor>. This filehandle must be	1218	Return the I<request result pipe file descriptor>. This filehandle must be
650	polled for reading by some mechanism outside this module (e.g. Event or	1219	polled for reading by some mechanism outside this module (e.g. EV, Glib,
651	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1220	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
652	to call C<poll_cb> to check the results.	1221	you have to call C<poll_cb> to check the results.
653		1222
654	See C<poll_cb> for an example.	1223	See C<poll_cb> for an example.
655		1224
656	=item IO::AIO::poll_cb	1225	=item IO::AIO::poll_cb
657		1226
658	Process all outstanding events on the result pipe. You have to call this	1227	Process some outstanding events on the result pipe. You have to call this
659	regularly. Returns the number of events processed. Returns immediately	1228	regularly. Returns C<0> if all events could be processed, or C<-1> if it
660	when no events are outstanding.	1229	returned earlier for whatever reason. Returns immediately when no events
		1230	are outstanding. The amount of events processed depends on the settings of
		1231	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1232
		1233	If not all requests were processed for whatever reason, the filehandle
		1234	will still be ready when C<poll_cb> returns, so normally you don't have to
		1235	do anything special to have it called later.
661		1236
662	Example: Install an Event watcher that automatically calls	1237	Example: Install an Event watcher that automatically calls
663	IO::AIO::poll_cb with high priority:	1238	IO::AIO::poll_cb with high priority (more examples can be found in the
		1239	SYNOPSIS section, at the top of this document):
664		1240
665	Event->io (fd => IO::AIO::poll_fileno,	1241	Event->io (fd => IO::AIO::poll_fileno,
666	poll => 'r', async => 1,	1242	poll => 'r', async => 1,
667	cb => \&IO::AIO::poll_cb);	1243	cb => \&IO::AIO::poll_cb);
668		1244
		1245	=item IO::AIO::max_poll_reqs $nreqs
		1246
		1247	=item IO::AIO::max_poll_time $seconds
		1248
		1249	These set the maximum number of requests (default C<0>, meaning infinity)
		1250	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1251	the maximum amount of time (default C<0>, meaning infinity) spent in
		1252	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1253	of time C<poll_cb> is allowed to use).
		1254
		1255	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1256	syscall per request processed, which is not normally a problem unless your
		1257	callbacks are really really fast or your OS is really really slow (I am
		1258	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1259
		1260	Setting these is useful if you want to ensure some level of
		1261	interactiveness when perl is not fast enough to process all requests in
		1262	time.
		1263
		1264	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1265
		1266	Example: Install an Event watcher that automatically calls
		1267	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1268	program get the CPU sometimes even under high AIO load.
		1269
		1270	# try not to spend much more than 0.1s in poll_cb
		1271	IO::AIO::max_poll_time 0.1;
		1272
		1273	# use a low priority so other tasks have priority
		1274	Event->io (fd => IO::AIO::poll_fileno,
		1275	poll => 'r', nice => 1,
		1276	cb => &IO::AIO::poll_cb);
		1277
669	=item IO::AIO::poll_wait	1278	=item IO::AIO::poll_wait
670		1279
		1280	If there are any outstanding requests and none of them in the result
671	Wait till the result filehandle becomes ready for reading (simply does a	1281	phase, wait till the result filehandle becomes ready for reading (simply
672	C<select> on the filehandle. This is useful if you want to synchronously wait	1282	does a C<select> on the filehandle. This is useful if you want to
673	for some requests to finish).	1283	synchronously wait for some requests to finish).
674		1284
675	See C<nreqs> for an example.	1285	See C<nreqs> for an example.
676		1286
		1287	=item IO::AIO::poll
		1288
		1289	Waits until some requests have been handled.
		1290
		1291	Returns the number of requests processed, but is otherwise strictly
		1292	equivalent to:
		1293
		1294	IO::AIO::poll_wait, IO::AIO::poll_cb
		1295
677	=item IO::AIO::nreqs	1296	=item IO::AIO::flush
678		1297
679	Returns the number of requests currently outstanding (i.e. for which their	1298	Wait till all outstanding AIO requests have been handled.
680	callback has not been invoked yet).
681		1299
682	Example: wait till there are no outstanding requests anymore:	1300	Strictly equivalent to:
683		1301
684	IO::AIO::poll_wait, IO::AIO::poll_cb	1302	IO::AIO::poll_wait, IO::AIO::poll_cb
685	while IO::AIO::nreqs;	1303	while IO::AIO::nreqs;
686		1304
687	=item IO::AIO::flush	1305	=back
688		1306
689	Wait till all outstanding AIO requests have been handled.	1307	=head3 CONTROLLING THE NUMBER OF THREADS
690		1308
691	Strictly equivalent to:	1309	=over
692
693	IO::AIO::poll_wait, IO::AIO::poll_cb
694	while IO::AIO::nreqs;
695
696	=item IO::AIO::poll
697
698	Waits until some requests have been handled.
699
700	Strictly equivalent to:
701
702	IO::AIO::poll_wait, IO::AIO::poll_cb
703	if IO::AIO::nreqs;
704		1310
705	=item IO::AIO::min_parallel $nthreads	1311	=item IO::AIO::min_parallel $nthreads
706		1312
707	Set the minimum number of AIO threads to C<$nthreads>. The current default	1313	Set the minimum number of AIO threads to C<$nthreads>. The current
708	is C<4>, which means four asynchronous operations can be done at one time	1314	default is C<8>, which means eight asynchronous operations can execute
709	(the number of outstanding operations, however, is unlimited).	1315	concurrently at any one time (the number of outstanding requests,
		1316	however, is unlimited).
710		1317
711	IO::AIO starts threads only on demand, when an AIO request is queued and	1318	IO::AIO starts threads only on demand, when an AIO request is queued and
712	no free thread exists.	1319	no free thread exists. Please note that queueing up a hundred requests can
		1320	create demand for a hundred threads, even if it turns out that everything
		1321	is in the cache and could have been processed faster by a single thread.
713		1322
714	It is recommended to keep the number of threads low, as some Linux	1323	It is recommended to keep the number of threads relatively low, as some
715	kernel versions will scale negatively with the number of threads (higher	1324	Linux kernel versions will scale negatively with the number of threads
716	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1325	(higher parallelity => MUCH higher latency). With current Linux 2.6
717	threads should be fine.	1326	versions, 4-32 threads should be fine.
718		1327
719	Under most circumstances you don't need to call this function, as the	1328	Under most circumstances you don't need to call this function, as the
720	module selects a default that is suitable for low to moderate load.	1329	module selects a default that is suitable for low to moderate load.
721		1330
722	=item IO::AIO::max_parallel $nthreads	1331	=item IO::AIO::max_parallel $nthreads
…		…
731	This module automatically runs C<max_parallel 0> at program end, to ensure	1340	This module automatically runs C<max_parallel 0> at program end, to ensure
732	that all threads are killed and that there are no outstanding requests.	1341	that all threads are killed and that there are no outstanding requests.
733		1342
734	Under normal circumstances you don't need to call this function.	1343	Under normal circumstances you don't need to call this function.
735		1344
		1345	=item IO::AIO::max_idle $nthreads
		1346
		1347	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1348	threads that did not get a request to process within 10 seconds). That
		1349	means if a thread becomes idle while C<$nthreads> other threads are also
		1350	idle, it will free its resources and exit.
		1351
		1352	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1353	to allow for extremely high load situations, but want to free resources
		1354	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1355
		1356	The default is probably ok in most situations, especially if thread
		1357	creation is fast. If thread creation is very slow on your system you might
		1358	want to use larger values.
		1359
736	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1360	=item IO::AIO::max_outstanding $maxreqs
		1361
		1362	This is a very bad function to use in interactive programs because it
		1363	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1364	use an C<aio_group> together with a feed callback.
737		1365
738	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1366	Sets the maximum number of outstanding requests to C<$nreqs>. If you
739	try to queue up more than this number of requests, the caller will block until	1367	do queue up more than this number of requests, the next call to the
740	some requests have been handled.	1368	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1369	function will block until the limit is no longer exceeded.
741		1370
742	The default is very large, so normally there is no practical limit. If you	1371	The default value is very large, so there is no practical limit on the
743	queue up many requests in a loop it often improves speed if you set	1372	number of outstanding requests.
744	this to a relatively low number, such as C<100>.
745		1373
746	Under normal circumstances you don't need to call this function.	1374	You can still queue as many requests as you want. Therefore,
		1375	C<max_outstanding> is mainly useful in simple scripts (with low values) or
		1376	as a stop gap to shield against fatal memory overflow (with large values).
747		1377
748	=back	1378	=back
749		1379
		1380	=head3 STATISTICAL INFORMATION
		1381
		1382	=over
		1383
		1384	=item IO::AIO::nreqs
		1385
		1386	Returns the number of requests currently in the ready, execute or pending
		1387	states (i.e. for which their callback has not been invoked yet).
		1388
		1389	Example: wait till there are no outstanding requests anymore:
		1390
		1391	IO::AIO::poll_wait, IO::AIO::poll_cb
		1392	while IO::AIO::nreqs;
		1393
		1394	=item IO::AIO::nready
		1395
		1396	Returns the number of requests currently in the ready state (not yet
		1397	executed).
		1398
		1399	=item IO::AIO::npending
		1400
		1401	Returns the number of requests currently in the pending state (executed,
		1402	but not yet processed by poll_cb).
		1403
		1404	=back
		1405
		1406	=head3 MISCELLANEOUS FUNCTIONS
		1407
		1408	IO::AIO implements some functions that might be useful, but are not
		1409	asynchronous.
		1410
		1411	=over 4
		1412
		1413	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1414
		1415	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1416	but is blocking (this makes most sense if you know the input data is
		1417	likely cached already and the output filehandle is set to non-blocking
		1418	operations).
		1419
		1420	Returns the number of bytes copied, or C<-1> on error.
		1421
		1422	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1423
		1424	Simply calls the C<posix_fadvise> function (see it's
		1425	manpage for details). The following advice constants are
		1426	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1427	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1428	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1429
		1430	On systems that do not implement C<posix_fadvise>, this function returns
		1431	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1432
		1433	=back
		1434
750	=cut	1435	=cut
751		1436
752	# support function to convert a fd into a perl filehandle
753	sub _fd2fh {
754	return undef if $_[0] < 0;
755
756	# try to generate nice filehandles
757	my $sym = "IO::AIO::fd#$_[0]";
758	local *$sym;
759
760	open *$sym, "+<&=$_[0]" # usually works under any unix
761	or open *$sym, "<&=$_[0]" # cygwin needs this
762	or open *$sym, ">&=$_[0]" # or this
763	or return undef;
764
765	*$sym
766	}
767
768	min_parallel 4;	1437	min_parallel 8;
769		1438
770	END {	1439	END { flush }
771	max_parallel 0;
772	}
773		1440
774	1;	1441	1;
775		1442
776	=head2 FORK BEHAVIOUR	1443	=head2 FORK BEHAVIOUR
777		1444
778	This module should do "the right thing" when the process using it forks:	1445	This module should do "the right thing" when the process using it forks:
779		1446
780	Before the fork, IO::AIO enters a quiescent state where no requests	1447	Before the fork, IO::AIO enters a quiescent state where no requests
781	can be added in other threads and no results will be processed. After	1448	can be added in other threads and no results will be processed. After
782	the fork the parent simply leaves the quiescent state and continues	1449	the fork the parent simply leaves the quiescent state and continues
783	request/result processing, while the child clears the request/result	1450	request/result processing, while the child frees the request/result queue
784	queue (so the requests started before the fork will only be handled in	1451	(so that the requests started before the fork will only be handled in the
785	the parent). Threads will be started on demand until the limit ste in the	1452	parent). Threads will be started on demand until the limit set in the
786	parent process has been reached again.	1453	parent process has been reached again.
787		1454
788	In short: the parent will, after a short pause, continue as if fork had	1455	In short: the parent will, after a short pause, continue as if fork had
789	not been called, while the child will act as if IO::AIO has not been used	1456	not been called, while the child will act as if IO::AIO has not been used
790	yet.	1457	yet.
791		1458
		1459	=head2 MEMORY USAGE
		1460
		1461	Per-request usage:
		1462
		1463	Each aio request uses - depending on your architecture - around 100-200
		1464	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1465	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1466	scalars and other data passed into aio requests will also be locked and
		1467	will consume memory till the request has entered the done state.
		1468
		1469	This is not awfully much, so queuing lots of requests is not usually a
		1470	problem.
		1471
		1472	Per-thread usage:
		1473
		1474	In the execution phase, some aio requests require more memory for
		1475	temporary buffers, and each thread requires a stack and other data
		1476	structures (usually around 16k-128k, depending on the OS).
		1477
		1478	=head1 KNOWN BUGS
		1479
		1480	Known bugs will be fixed in the next release.
		1481
792	=head1 SEE ALSO	1482	=head1 SEE ALSO
793		1483
794	L<Coro>, L<Linux::AIO> (obsolete).	1484	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1485	more natural syntax.
795		1486
796	=head1 AUTHOR	1487	=head1 AUTHOR
797		1488
798	Marc Lehmann <schmorp@schmorp.de>	1489	Marc Lehmann <schmorp@schmorp.de>
799	http://home.schmorp.de/	1490	http://home.schmorp.de/

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