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Revision 1.85 by root, Sat Oct 28 01:40:30 2006 UTC vs.
Revision 1.184 by root, Mon Nov 1 22:03:43 2010 UTC

…		…
4		4
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", IO::AIO::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
…		…
25	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
26		27
27	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
28	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
29		30
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
35	Event->io (fd => IO::AIO::poll_fileno,
36	poll => 'r',
37	cb => \&IO::AIO::poll_cb);
38
39	# Glib/Gtk2 integration
40	add_watch Glib::IO IO::AIO::poll_fileno,
41	in => sub { IO::AIO::poll_cb; 1 };
42
43	# Tk integration
44	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
45	readable => \&IO::AIO::poll_cb);
46
47	# Danga::Socket integration
48	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
49	\&IO::AIO::poll_cb);
50
51	=head1 DESCRIPTION	31	=head1 DESCRIPTION
52		32
53	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
54	operating system supports.	34	operating system supports. It is implemented as an interface to C<libeio>
		35	(L<http://software.schmorp.de/pkg/libeio.html>).
55		36
56	Asynchronous means that operations that can normally block your program	37	Asynchronous means that operations that can normally block your program
57	(e.g. reading from disk) will be done asynchronously: the operation	38	(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	39	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	40	is extremely useful for programs that need to stay interactive even
…		…
61	etc.), but can also be used to easily do operations in parallel that are	42	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	43	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	44	on a RAID volume or over NFS when you do a number of stat operations
64	concurrently.	45	concurrently.
65		46
66	While this works on all types of file descriptors (for example sockets),	47	While most of this works on all types of file descriptors (for
67	using these functions on file descriptors that support nonblocking	48	example sockets), using these functions on file descriptors that
68	operation (again, sockets, pipes etc.) is very inefficient. Use an event	49	support nonblocking operation (again, sockets, pipes etc.) is
69	loop for that (such as the L<Event|Event> module): IO::AIO will naturally	50	very inefficient. Use an event loop for that (such as the L<EV>
70	fit into such an event loop itself.	51	module): IO::AIO will naturally fit into such an event loop itself.
71		52
72	In this version, a number of threads are started that execute your	53	In this version, a number of threads are started that execute your
73	requests and signal their completion. You don't need thread support	54	requests and signal their completion. You don't need thread support
74	in perl, and the threads created by this module will not be visible	55	in perl, and the threads created by this module will not be visible
75	to perl. In the future, this module might make use of the native aio	56	to perl. In the future, this module might make use of the native aio
…		…
77	not well-supported or restricted (GNU/Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
78	files currently, for example), and they would only support aio_read and	59	files currently, for example), and they would only support aio_read and
79	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
80	using threads anyway.	61	using threads anyway.
81		62
82	Although the module will work with in the presence of other (Perl-)	63	Although the module will work in the presence of other (Perl-) threads,
83	threads, it is currently not reentrant in any way, so use appropriate	64	it is currently not reentrant in any way, so use appropriate locking
84	locking yourself, always call C<poll_cb> from within the same thread, or	65	yourself, always call C<poll_cb> from within the same thread, or never
85	never call C<poll_cb> (or other C<aio_> functions) recursively.	66	call C<poll_cb> (or other C<aio_> functions) recursively.
		67
		68	=head2 EXAMPLE
		69
		70	This is a simple example that uses the EV module and loads
		71	F</etc/passwd> asynchronously:
		72
		73	use Fcntl;
		74	use EV;
		75	use IO::AIO;
		76
		77	# register the IO::AIO callback with EV
		78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		79
		80	# queue the request to open /etc/passwd
		81	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
		82	my $fh = shift
		83	or die "error while opening: $!";
		84
		85	# stat'ing filehandles is generally non-blocking
		86	my $size = -s $fh;
		87
		88	# queue a request to read the file
		89	my $contents;
		90	aio_read $fh, 0, $size, $contents, 0, sub {
		91	$_[0] == $size
		92	or die "short read: $!";
		93
		94	close $fh;
		95
		96	# file contents now in $contents
		97	print $contents;
		98
		99	# exit event loop and program
		100	EV::unloop;
		101	};
		102	};
		103
		104	# possibly queue up other requests, or open GUI windows,
		105	# check for sockets etc. etc.
		106
		107	# process events as long as there are some:
		108	EV::loop;
86		109
87	=head1 REQUEST ANATOMY AND LIFETIME	110	=head1 REQUEST ANATOMY AND LIFETIME
88		111
89	Every C<aio_*> function creates a request. which is a C data structure not	112	Every C<aio_*> function creates a request. which is a C data structure not
90	directly visible to Perl.	113	directly visible to Perl.
…		…
132	Request has reached the end of its lifetime and holds no resources anymore	155	Request has reached the end of its lifetime and holds no resources anymore
133	(except possibly for the Perl object, but its connection to the actual	156	(except possibly for the Perl object, but its connection to the actual
134	aio request is severed and calling its methods will either do nothing or	157	aio request is severed and calling its methods will either do nothing or
135	result in a runtime error).	158	result in a runtime error).
136		159
		160	=back
		161
137	=cut	162	=cut
138		163
139	package IO::AIO;	164	package IO::AIO;
140		165
141	no warnings;	166	use Carp ();
142	use strict 'vars';	167
		168	use common::sense;
143		169
144	use base 'Exporter';	170	use base 'Exporter';
145		171
146	BEGIN {	172	BEGIN {
147	our $VERSION = '2.0';	173	our $VERSION = '3.7';
148		174
149	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
150	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
151	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	177	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
152	aio_copy aio_group aio_nop aio_mknod);	178	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
		179	aio_rename aio_link aio_move aio_copy aio_group
		180	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		181	aio_chmod aio_utime aio_truncate
		182	aio_msync aio_mtouch aio_mlock aio_mlockall
		183	aio_statvfs);
		184
153	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
154	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
155	min_parallel max_parallel nreqs nready npending);	187	min_parallel max_parallel max_idle
		188	nreqs nready npending nthreads
		189	max_poll_time max_poll_reqs
		190	sendfile fadvise madvise
		191	mmap munmap munlock munlockall);
		192
		193	push @AIO_REQ, qw(aio_busy); # not exported
156		194
157	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	195	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
158		196
159	require XSLoader;	197	require XSLoader;
160	XSLoader::load ("IO::AIO", $VERSION);	198	XSLoader::load ("IO::AIO", $VERSION);
161	}	199	}
162		200
163	=head1 FUNCTIONS	201	=head1 FUNCTIONS
164		202
		203	=head2 QUICK OVERVIEW
		204
		205	This section simply lists the prototypes of the most important functions
		206	for quick reference. See the following sections for function-by-function
		207	documentation.
		208
		209	aio_open $pathname, $flags, $mode, $callback->($fh)
		210	aio_close $fh, $callback->($status)
		211	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		212	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		213	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		214	aio_readahead $fh,$offset,$length, $callback->($retval)
		215	aio_stat $fh_or_path, $callback->($status)
		216	aio_lstat $fh, $callback->($status)
		217	aio_statvfs $fh_or_path, $callback->($statvfs)
		218	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		219	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		220	aio_truncate $fh_or_path, $offset, $callback->($status)
		221	aio_chmod $fh_or_path, $mode, $callback->($status)
		222	aio_unlink $pathname, $callback->($status)
		223	aio_mknod $path, $mode, $dev, $callback->($status)
		224	aio_link $srcpath, $dstpath, $callback->($status)
		225	aio_symlink $srcpath, $dstpath, $callback->($status)
		226	aio_readlink $path, $callback->($link)
		227	aio_rename $srcpath, $dstpath, $callback->($status)
		228	aio_mkdir $pathname, $mode, $callback->($status)
		229	aio_rmdir $pathname, $callback->($status)
		230	aio_readdir $pathname, $callback->($entries)
		231	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		232	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		233	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		234	aio_load $path, $data, $callback->($status)
		235	aio_copy $srcpath, $dstpath, $callback->($status)
		236	aio_move $srcpath, $dstpath, $callback->($status)
		237	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		238	aio_rmtree $path, $callback->($status)
		239	aio_sync $callback->($status)
		240	aio_fsync $fh, $callback->($status)
		241	aio_fdatasync $fh, $callback->($status)
		242	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		243	aio_pathsync $path, $callback->($status)
		244	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		245	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		246	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		247	aio_mlockall $flags, $callback->($status)
		248	aio_group $callback->(...)
		249	aio_nop $callback->()
		250
		251	$prev_pri = aioreq_pri [$pri]
		252	aioreq_nice $pri_adjust
		253
		254	IO::AIO::poll_wait
		255	IO::AIO::poll_cb
		256	IO::AIO::poll
		257	IO::AIO::flush
		258	IO::AIO::max_poll_reqs $nreqs
		259	IO::AIO::max_poll_time $seconds
		260	IO::AIO::min_parallel $nthreads
		261	IO::AIO::max_parallel $nthreads
		262	IO::AIO::max_idle $nthreads
		263	IO::AIO::max_outstanding $maxreqs
		264	IO::AIO::nreqs
		265	IO::AIO::nready
		266	IO::AIO::npending
		267
		268	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		269	IO::AIO::fadvise $fh, $offset, $len, $advice
		270	IO::AIO::madvise $scalar, $offset, $length, $advice
		271	IO::AIO::mprotect $scalar, $offset, $length, $protect
		272	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		273	IO::AIO::munlockall
		274
165	=head2 AIO FUNCTIONS	275	=head2 AIO REQUEST FUNCTIONS
166		276
167	All the C<aio_*> calls are more or less thin wrappers around the syscall	277	All the C<aio_*> calls are more or less thin wrappers around the syscall
168	with the same name (sans C<aio_>). The arguments are similar or identical,	278	with the same name (sans C<aio_>). The arguments are similar or identical,
169	and they all accept an additional (and optional) C<$callback> argument	279	and they all accept an additional (and optional) C<$callback> argument
170	which must be a code reference. This code reference will get called with	280	which must be a code reference. This code reference will get called with
171	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	281	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
172	perl, which usually delivers "false") as it's sole argument when the given	282	perl, which usually delivers "false") as its sole argument after the given
173	syscall has been executed asynchronously.	283	syscall has been executed asynchronously.
174		284
175	All functions expecting a filehandle keep a copy of the filehandle	285	All functions expecting a filehandle keep a copy of the filehandle
176	internally until the request has finished.	286	internally until the request has finished.
177		287
178	All requests return objects of type L<IO::AIO::REQ> that allow further	288	All functions return request objects of type L<IO::AIO::REQ> that allow
179	manipulation of those requests while they are in-flight.	289	further manipulation of those requests while they are in-flight.
180		290
181	The pathnames you pass to these routines I<must> be absolute and	291	The pathnames you pass to these routines I<must> be absolute and
182	encoded in byte form. The reason for the former is that at the time the	292	encoded as octets. The reason for the former is that at the time the
183	request is being executed, the current working directory could have	293	request is being executed, the current working directory could have
184	changed. Alternatively, you can make sure that you never change the	294	changed. Alternatively, you can make sure that you never change the
185	current working directory.	295	current working directory anywhere in the program and then use relative
		296	paths.
186		297
187	To encode pathnames to byte form, either make sure you either: a)	298	To encode pathnames as octets, either make sure you either: a) always pass
188	always pass in filenames you got from outside (command line, readdir	299	in filenames you got from outside (command line, readdir etc.) without
189	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	300	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
190	your pathnames to the locale (or other) encoding in effect in the user	301	your pathnames to the locale (or other) encoding in effect in the user
191	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	302	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
192	use something else.	303	use something else to ensure your scalar has the correct contents.
		304
		305	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		306	handles correctly whether it is set or not.
193		307
194	=over 4	308	=over 4
195		309
196	=item $prev_pri = aioreq_pri [$pri]	310	=item $prev_pri = aioreq_pri [$pri]
197		311
…		…
217	aio_read $_[0], ..., sub {	331	aio_read $_[0], ..., sub {
218	...	332	...
219	};	333	};
220	};	334	};
221		335
		336
222	=item aioreq_nice $pri_adjust	337	=item aioreq_nice $pri_adjust
223		338
224	Similar to C<aioreq_pri>, but subtracts the given value from the current	339	Similar to C<aioreq_pri>, but subtracts the given value from the current
225	priority, so effects are cumulative.	340	priority, so the effect is cumulative.
		341
226		342
227	=item aio_open $pathname, $flags, $mode, $callback->($fh)	343	=item aio_open $pathname, $flags, $mode, $callback->($fh)
228		344
229	Asynchronously open or create a file and call the callback with a newly	345	Asynchronously open or create a file and call the callback with a newly
230	created filehandle for the file.	346	created filehandle for the file.
…		…
236	list. They are the same as used by C<sysopen>.	352	list. They are the same as used by C<sysopen>.
237		353
238	Likewise, C<$mode> specifies the mode of the newly created file, if it	354	Likewise, C<$mode> specifies the mode of the newly created file, if it
239	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	355	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
240	except that it is mandatory (i.e. use C<0> if you don't create new files,	356	except that it is mandatory (i.e. use C<0> if you don't create new files,
241	and C<0666> or C<0777> if you do).	357	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		358	by the umask in effect then the request is being executed, so better never
		359	change the umask.
242		360
243	Example:	361	Example:
244		362
245	aio_open "/etc/passwd", O_RDONLY, 0, sub {	363	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
246	if ($_[0]) {	364	if ($_[0]) {
247	print "open successful, fh is $_[0]\n";	365	print "open successful, fh is $_[0]\n";
248	...	366	...
249	} else {	367	} else {
250	die "open failed: $!\n";	368	die "open failed: $!\n";
251	}	369	}
252	};	370	};
253		371
		372
254	=item aio_close $fh, $callback->($status)	373	=item aio_close $fh, $callback->($status)
255		374
256	Asynchronously close a file and call the callback with the result	375	Asynchronously close a file and call the callback with the result
257	code. I<WARNING:> although accepted, you should not pass in a perl	376	code.
258	filehandle here, as perl will likely close the file descriptor another
259	time when the filehandle is destroyed. Normally, you can safely call perls
260	C<close> or just let filehandles go out of scope.
261		377
262	This is supposed to be a bug in the API, so that might change. It's	378	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
263	therefore best to avoid this function.	379	closing the file descriptor associated with the filehandle itself.
		380
		381	Therefore, C<aio_close> will not close the filehandle - instead it will
		382	use dup2 to overwrite the file descriptor with the write-end of a pipe
		383	(the pipe fd will be created on demand and will be cached).
		384
		385	Or in other words: the file descriptor will be closed, but it will not be
		386	free for reuse until the perl filehandle is closed.
		387
		388	=cut
264		389
265	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	390	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
266		391
267	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	392	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
268		393
269	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	394	Reads or writes C<$length> bytes from or to the specified C<$fh> and
270	into the scalar given by C<data> and offset C<dataoffset> and calls the	395	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
271	callback without the actual number of bytes read (or -1 on error, just	396	and calls the callback without the actual number of bytes read (or -1 on
272	like the syscall).	397	error, just like the syscall).
		398
		399	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		400	offset plus the actual number of bytes read.
		401
		402	If C<$offset> is undefined, then the current file descriptor offset will
		403	be used (and updated), otherwise the file descriptor offset will not be
		404	changed by these calls.
		405
		406	If C<$length> is undefined in C<aio_write>, use the remaining length of
		407	C<$data>.
		408
		409	If C<$dataoffset> is less than zero, it will be counted from the end of
		410	C<$data>.
273		411
274	The C<$data> scalar I<MUST NOT> be modified in any way while the request	412	The C<$data> scalar I<MUST NOT> be modified in any way while the request
275	is outstanding. Modifying it can result in segfaults or WW3 (if the	413	is outstanding. Modifying it can result in segfaults or World War III (if
276	necessary/optional hardware is installed).	414	the necessary/optional hardware is installed).
277		415
278	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	416	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
279	offset C<0> within the scalar:	417	offset C<0> within the scalar:
280		418
281	aio_read $fh, 7, 15, $buffer, 0, sub {	419	aio_read $fh, 7, 15, $buffer, 0, sub {
282	$_[0] > 0 or die "read error: $!";	420	$_[0] > 0 or die "read error: $!";
283	print "read $_[0] bytes: <$buffer>\n";	421	print "read $_[0] bytes: <$buffer>\n";
284	};	422	};
		423
285		424
286	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	425	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
287		426
288	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	427	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
289	reading at byte offset C<$in_offset>, and starts writing at the current	428	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
291	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	430	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
292	other.	431	other.
293		432
294	This call tries to make use of a native C<sendfile> syscall to provide	433	This call tries to make use of a native C<sendfile> syscall to provide
295	zero-copy operation. For this to work, C<$out_fh> should refer to a	434	zero-copy operation. For this to work, C<$out_fh> should refer to a
296	socket, and C<$in_fh> should refer to mmap'able file.	435	socket, and C<$in_fh> should refer to an mmap'able file.
297		436
298	If the native sendfile call fails or is not implemented, it will be	437	If a native sendfile cannot be found or it fails with C<ENOSYS>,
		438	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,
299	emulated, so you can call C<aio_sendfile> on any type of filehandle	439	it will be emulated, so you can call C<aio_sendfile> on any type of
300	regardless of the limitations of the operating system.	440	filehandle regardless of the limitations of the operating system.
301		441
302	Please note, however, that C<aio_sendfile> can read more bytes from	442	Please note, however, that C<aio_sendfile> can read more bytes from
303	C<$in_fh> than are written, and there is no way to find out how many	443	C<$in_fh> than are written, and there is no way to find out how many
304	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	444	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
305	provides the number of bytes written to C<$out_fh>. Only if the result	445	provides the number of bytes written to C<$out_fh>. Only if the result
306	value equals C<$length> one can assume that C<$length> bytes have been	446	value equals C<$length> one can assume that C<$length> bytes have been
307	read.	447	read.
		448
308		449
309	=item aio_readahead $fh,$offset,$length, $callback->($retval)	450	=item aio_readahead $fh,$offset,$length, $callback->($retval)
310		451
311	C<aio_readahead> populates the page cache with data from a file so that	452	C<aio_readahead> populates the page cache with data from a file so that
312	subsequent reads from that file will not block on disk I/O. The C<$offset>	453	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
318	file. The current file offset of the file is left unchanged.	459	file. The current file offset of the file is left unchanged.
319		460
320	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	461	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
321	emulated by simply reading the data, which would have a similar effect.	462	emulated by simply reading the data, which would have a similar effect.
322		463
		464
323	=item aio_stat $fh_or_path, $callback->($status)	465	=item aio_stat $fh_or_path, $callback->($status)
324		466
325	=item aio_lstat $fh, $callback->($status)	467	=item aio_lstat $fh, $callback->($status)
326		468
327	Works like perl's C<stat> or C<lstat> in void context. The callback will	469	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
340	aio_stat "/etc/passwd", sub {	482	aio_stat "/etc/passwd", sub {
341	$_[0] and die "stat failed: $!";	483	$_[0] and die "stat failed: $!";
342	print "size is ", -s _, "\n";	484	print "size is ", -s _, "\n";
343	};	485	};
344		486
		487
		488	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		489
		490	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		491	whether a file handle or path was passed.
		492
		493	On success, the callback is passed a hash reference with the following
		494	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		495	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		496	is passed.
		497
		498	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		499	C<ST_NOSUID>.
		500
		501	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		502	their correct value when available, or to C<0> on systems that do
		503	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		504	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		505	C<ST_NODIRATIME> and C<ST_RELATIME>.
		506
		507	Example: stat C</wd> and dump out the data if successful.
		508
		509	aio_statvfs "/wd", sub {
		510	my $f = $_[0]
		511	or die "statvfs: $!";
		512
		513	use Data::Dumper;
		514	say Dumper $f;
		515	};
		516
		517	# result:
		518	{
		519	bsize => 1024,
		520	bfree => 4333064312,
		521	blocks => 10253828096,
		522	files => 2050765568,
		523	flag => 4096,
		524	favail => 2042092649,
		525	bavail => 4333064312,
		526	ffree => 2042092649,
		527	namemax => 255,
		528	frsize => 1024,
		529	fsid => 1810
		530	}
		531
		532
		533	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		534
		535	Works like perl's C<utime> function (including the special case of $atime
		536	and $mtime being undef). Fractional times are supported if the underlying
		537	syscalls support them.
		538
		539	When called with a pathname, uses utimes(2) if available, otherwise
		540	utime(2). If called on a file descriptor, uses futimes(2) if available,
		541	otherwise returns ENOSYS, so this is not portable.
		542
		543	Examples:
		544
		545	# set atime and mtime to current time (basically touch(1)):
		546	aio_utime "path", undef, undef;
		547	# set atime to current time and mtime to beginning of the epoch:
		548	aio_utime "path", time, undef; # undef==0
		549
		550
		551	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		552
		553	Works like perl's C<chown> function, except that C<undef> for either $uid
		554	or $gid is being interpreted as "do not change" (but -1 can also be used).
		555
		556	Examples:
		557
		558	# same as "chown root path" in the shell:
		559	aio_chown "path", 0, -1;
		560	# same as above:
		561	aio_chown "path", 0, undef;
		562
		563
		564	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		565
		566	Works like truncate(2) or ftruncate(2).
		567
		568
		569	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		570
		571	Works like perl's C<chmod> function.
		572
		573
345	=item aio_unlink $pathname, $callback->($status)	574	=item aio_unlink $pathname, $callback->($status)
346		575
347	Asynchronously unlink (delete) a file and call the callback with the	576	Asynchronously unlink (delete) a file and call the callback with the
348	result code.	577	result code.
349		578
		579
350	=item aio_mknod $path, $mode, $dev, $callback->($status)	580	=item aio_mknod $path, $mode, $dev, $callback->($status)
351		581
		582	[EXPERIMENTAL]
		583
352	Asynchronously create a device node (or fifo). See mknod(2).	584	Asynchronously create a device node (or fifo). See mknod(2).
353		585
354	The only portable (POSIX) way of calling this function is:	586	The only (POSIX-) portable way of calling this function is:
355		587
356	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	588	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		589
357		590
358	=item aio_link $srcpath, $dstpath, $callback->($status)	591	=item aio_link $srcpath, $dstpath, $callback->($status)
359		592
360	Asynchronously create a new link to the existing object at C<$srcpath> at	593	Asynchronously create a new link to the existing object at C<$srcpath> at
361	the path C<$dstpath> and call the callback with the result code.	594	the path C<$dstpath> and call the callback with the result code.
362		595
		596
363	=item aio_symlink $srcpath, $dstpath, $callback->($status)	597	=item aio_symlink $srcpath, $dstpath, $callback->($status)
364		598
365	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	599	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
366	the path C<$dstpath> and call the callback with the result code.	600	the path C<$dstpath> and call the callback with the result code.
367		601
		602
		603	=item aio_readlink $path, $callback->($link)
		604
		605	Asynchronously read the symlink specified by C<$path> and pass it to
		606	the callback. If an error occurs, nothing or undef gets passed to the
		607	callback.
		608
		609
368	=item aio_rename $srcpath, $dstpath, $callback->($status)	610	=item aio_rename $srcpath, $dstpath, $callback->($status)
369		611
370	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	612	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
371	rename(2) and call the callback with the result code.	613	rename(2) and call the callback with the result code.
372		614
		615
		616	=item aio_mkdir $pathname, $mode, $callback->($status)
		617
		618	Asynchronously mkdir (create) a directory and call the callback with
		619	the result code. C<$mode> will be modified by the umask at the time the
		620	request is executed, so do not change your umask.
		621
		622
373	=item aio_rmdir $pathname, $callback->($status)	623	=item aio_rmdir $pathname, $callback->($status)
374		624
375	Asynchronously rmdir (delete) a directory and call the callback with the	625	Asynchronously rmdir (delete) a directory and call the callback with the
376	result code.	626	result code.
		627
377		628
378	=item aio_readdir $pathname, $callback->($entries)	629	=item aio_readdir $pathname, $callback->($entries)
379		630
380	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	631	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
381	directory (i.e. opendir + readdir + closedir). The entries will not be	632	directory (i.e. opendir + readdir + closedir). The entries will not be
382	sorted, and will B<NOT> include the C<.> and C<..> entries.	633	sorted, and will B<NOT> include the C<.> and C<..> entries.
383		634
384	The callback a single argument which is either C<undef> or an array-ref	635	The callback is passed a single argument which is either C<undef> or an
385	with the filenames.	636	array-ref with the filenames.
		637
		638
		639	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		640
		641	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		642	behaviour and output format. In case of an error, C<$entries> will be
		643	C<undef>.
		644
		645	The flags are a combination of the following constants, ORed together (the
		646	flags will also be passed to the callback, possibly modified):
		647
		648	=over 4
		649
		650	=item IO::AIO::READDIR_DENTS
		651
		652	When this flag is off, then the callback gets an arrayref with of names
		653	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		654	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		655	entry in more detail.
		656
		657	C<$name> is the name of the entry.
		658
		659	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		660
		661	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		662	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		663	C<IO::AIO::DT_WHT>.
		664
		665	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		666	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		667	scalars are read-only: you can not modify them.
		668
		669	C<$inode> is the inode number (which might not be exact on systems with 64
		670	bit inode numbers and 32 bit perls). This field has unspecified content on
		671	systems that do not deliver the inode information.
		672
		673	=item IO::AIO::READDIR_DIRS_FIRST
		674
		675	When this flag is set, then the names will be returned in an order where
		676	likely directories come first. This is useful when you need to quickly
		677	find directories, or you want to find all directories while avoiding to
		678	stat() each entry.
		679
		680	If the system returns type information in readdir, then this is used
		681	to find directories directly. Otherwise, likely directories are files
		682	beginning with ".", or otherwise files with no dots, of which files with
		683	short names are tried first.
		684
		685	=item IO::AIO::READDIR_STAT_ORDER
		686
		687	When this flag is set, then the names will be returned in an order
		688	suitable for stat()'ing each one. That is, when you plan to stat()
		689	all files in the given directory, then the returned order will likely
		690	be fastest.
		691
		692	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		693	the likely dirs come first, resulting in a less optimal stat order.
		694
		695	=item IO::AIO::READDIR_FOUND_UNKNOWN
		696
		697	This flag should not be set when calling C<aio_readdirx>. Instead, it
		698	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		699	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		700	C<$type>'s are known, which can be used to speed up some algorithms.
		701
		702	=back
		703
		704
		705	=item aio_load $path, $data, $callback->($status)
		706
		707	This is a composite request that tries to fully load the given file into
		708	memory. Status is the same as with aio_read.
		709
		710	=cut
		711
		712	sub aio_load($$;$) {
		713	my ($path, undef, $cb) = @_;
		714	my $data = \$_[1];
		715
		716	my $pri = aioreq_pri;
		717	my $grp = aio_group $cb;
		718
		719	aioreq_pri $pri;
		720	add $grp aio_open $path, O_RDONLY, 0, sub {
		721	my $fh = shift
		722	or return $grp->result (-1);
		723
		724	aioreq_pri $pri;
		725	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		726	$grp->result ($_[0]);
		727	};
		728	};
		729
		730	$grp
		731	}
386		732
387	=item aio_copy $srcpath, $dstpath, $callback->($status)	733	=item aio_copy $srcpath, $dstpath, $callback->($status)
388		734
389	Try to copy the I<file> (directories not supported as either source or	735	Try to copy the I<file> (directories not supported as either source or
390	destination) from C<$srcpath> to C<$dstpath> and call the callback with	736	destination) from C<$srcpath> to C<$dstpath> and call the callback with
391	the C<0> (error) or C<-1> ok.	737	a status of C<0> (ok) or C<-1> (error, see C<$!>).
392		738
393	This is a composite request that it creates the destination file with	739	This is a composite request that creates the destination file with
394	mode 0200 and copies the contents of the source file into it using	740	mode 0200 and copies the contents of the source file into it using
395	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	741	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
396	uid/gid, in that order.	742	uid/gid, in that order.
397		743
398	If an error occurs, the partial destination file will be unlinked, if	744	If an error occurs, the partial destination file will be unlinked, if
…		…
408	my $grp = aio_group $cb;	754	my $grp = aio_group $cb;
409		755
410	aioreq_pri $pri;	756	aioreq_pri $pri;
411	add $grp aio_open $src, O_RDONLY, 0, sub {	757	add $grp aio_open $src, O_RDONLY, 0, sub {
412	if (my $src_fh = $_[0]) {	758	if (my $src_fh = $_[0]) {
413	my @stat = stat $src_fh;	759	my @stat = stat $src_fh; # hmm, might block over nfs?
414		760
415	aioreq_pri $pri;	761	aioreq_pri $pri;
416	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	762	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
417	if (my $dst_fh = $_[0]) {	763	if (my $dst_fh = $_[0]) {
418	aioreq_pri $pri;	764	aioreq_pri $pri;
419	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	765	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
420	if ($_[0] == $stat[7]) {	766	if ($_[0] == $stat[7]) {
421	$grp->result (0);	767	$grp->result (0);
422	close $src_fh;	768	close $src_fh;
423		769
424	# those should not normally block. should. should.	770	my $ch = sub {
		771	aioreq_pri $pri;
		772	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		773	aioreq_pri $pri;
		774	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		775	aioreq_pri $pri;
		776	add $grp aio_close $dst_fh;
		777	}
		778	};
		779	};
		780
		781	aioreq_pri $pri;
		782	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		783	if ($_[0] < 0 && $! == ENOSYS) {
		784	aioreq_pri $pri;
425	utime $stat[8], $stat[9], $dst;	785	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
426	chmod $stat[2] & 07777, $dst_fh;	786	} else {
427	chown $stat[4], $stat[5], $dst_fh;	787	$ch->();
		788	}
428	close $dst_fh;	789	};
429	} else {	790	} else {
430	$grp->result (-1);	791	$grp->result (-1);
431	close $src_fh;	792	close $src_fh;
432	close $dst_fh;	793	close $dst_fh;
433		794
…		…
450		811
451	=item aio_move $srcpath, $dstpath, $callback->($status)	812	=item aio_move $srcpath, $dstpath, $callback->($status)
452		813
453	Try to move the I<file> (directories not supported as either source or	814	Try to move the I<file> (directories not supported as either source or
454	destination) from C<$srcpath> to C<$dstpath> and call the callback with	815	destination) from C<$srcpath> to C<$dstpath> and call the callback with
455	the C<0> (error) or C<-1> ok.	816	a status of C<0> (ok) or C<-1> (error, see C<$!>).
456		817
457	This is a composite request that tries to rename(2) the file first. If	818	This is a composite request that tries to rename(2) the file first; if
458	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if	819	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
459	that is successful, unlinking the C<$srcpath>.	820	that is successful, unlinks the C<$srcpath>.
460		821
461	=cut	822	=cut
462		823
463	sub aio_move($$;$) {	824	sub aio_move($$;$) {
464	my ($src, $dst, $cb) = @_;	825	my ($src, $dst, $cb) = @_;
…		…
511		872
512	Implementation notes.	873	Implementation notes.
513		874
514	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	875	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
515		876
		877	If readdir returns file type information, then this is used directly to
		878	find directories.
		879
516	After reading the directory, the modification time, size etc. of the	880	Otherwise, after reading the directory, the modification time, size etc.
517	directory before and after the readdir is checked, and if they match (and	881	of the directory before and after the readdir is checked, and if they
518	isn't the current time), the link count will be used to decide how many	882	match (and isn't the current time), the link count will be used to decide
519	entries are directories (if >= 2). Otherwise, no knowledge of the number	883	how many entries are directories (if >= 2). Otherwise, no knowledge of the
520	of subdirectories will be assumed.	884	number of subdirectories will be assumed.
521		885
522	Then entries will be sorted into likely directories (everything without	886	Then entries will be sorted into likely directories a non-initial dot
523	a non-initial dot currently) and likely non-directories (everything	887	currently) and likely non-directories (see C<aio_readdirx>). Then every
524	else). Then every entry plus an appended C</.> will be C<stat>'ed,	888	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
525	likely directories first. If that succeeds, it assumes that the entry	889	in order of their inode numbers. If that succeeds, it assumes that the
526	is a directory or a symlink to directory (which will be checked	890	entry is a directory or a symlink to directory (which will be checked
527	seperately). This is often faster than stat'ing the entry itself because	891	seperately). This is often faster than stat'ing the entry itself because
528	filesystems might detect the type of the entry without reading the inode	892	filesystems might detect the type of the entry without reading the inode
529	data (e.g. ext2fs filetype feature).	893	data (e.g. ext2fs filetype feature), even on systems that cannot return
		894	the filetype information on readdir.
530		895
531	If the known number of directories (link count - 2) has been reached, the	896	If the known number of directories (link count - 2) has been reached, the
532	rest of the entries is assumed to be non-directories.	897	rest of the entries is assumed to be non-directories.
533		898
534	This only works with certainty on POSIX (= UNIX) filesystems, which	899	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
538	as those tend to return 0 or 1 as link counts, which disables the	903	as those tend to return 0 or 1 as link counts, which disables the
539	directory counting heuristic.	904	directory counting heuristic.
540		905
541	=cut	906	=cut
542		907
543	sub aio_scandir($$$) {	908	sub aio_scandir($$;$) {
544	my ($path, $maxreq, $cb) = @_;	909	my ($path, $maxreq, $cb) = @_;
545		910
546	my $pri = aioreq_pri;	911	my $pri = aioreq_pri;
547		912
548	my $grp = aio_group $cb;	913	my $grp = aio_group $cb;
…		…
556	my $now = time;	921	my $now = time;
557	my $hash1 = join ":", (stat _)[0,1,3,7,9];	922	my $hash1 = join ":", (stat _)[0,1,3,7,9];
558		923
559	# read the directory entries	924	# read the directory entries
560	aioreq_pri $pri;	925	aioreq_pri $pri;
561	add $grp aio_readdir $path, sub {	926	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
562	my $entries = shift	927	my $entries = shift
563	or return $grp->result ();	928	or return $grp->result ();
564		929
565	# stat the dir another time	930	# stat the dir another time
566	aioreq_pri $pri;	931	aioreq_pri $pri;
…		…
572	# take the slow route if anything looks fishy	937	# take the slow route if anything looks fishy
573	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	938	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
574	$ndirs = -1;	939	$ndirs = -1;
575	} else {	940	} else {
576	# if nlink == 2, we are finished	941	# if nlink == 2, we are finished
577	# on non-posix-fs's, we rely on nlink < 2	942	# for non-posix-fs's, we rely on nlink < 2
578	$ndirs = (stat _)[3] - 2	943	$ndirs = (stat _)[3] - 2
579	or return $grp->result ([], $entries);	944	or return $grp->result ([], $entries);
580	}	945	}
581		946
582	# sort into likely dirs and likely nondirs
583	# dirs == files without ".", short entries first
584	$entries = [map $_->[0],
585	sort { $b->[1] cmp $a->[1] }
586	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
587	@$entries];
588
589	my (@dirs, @nondirs);	947	my (@dirs, @nondirs);
590		948
591	my $statgrp = add $grp aio_group sub {	949	my $statgrp = add $grp aio_group sub {
592	$grp->result (\@dirs, \@nondirs);	950	$grp->result (\@dirs, \@nondirs);
593	};	951	};
594		952
595	limit $statgrp $maxreq;	953	limit $statgrp $maxreq;
596	feed $statgrp sub {	954	feed $statgrp sub {
597	return unless @$entries;	955	return unless @$entries;
598	my $entry = pop @$entries;	956	my $entry = shift @$entries;
599		957
600	aioreq_pri $pri;	958	aioreq_pri $pri;
601	add $statgrp aio_stat "$path/$entry/.", sub {	959	add $statgrp aio_stat "$path/$entry/.", sub {
602	if ($_[0] < 0) {	960	if ($_[0] < 0) {
603	push @nondirs, $entry;	961	push @nondirs, $entry;
…		…
624	};	982	};
625		983
626	$grp	984	$grp
627	}	985	}
628		986
		987	=item aio_rmtree $path, $callback->($status)
		988
		989	Delete a directory tree starting (and including) C<$path>, return the
		990	status of the final C<rmdir> only. This is a composite request that
		991	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		992	everything else.
		993
		994	=cut
		995
		996	sub aio_rmtree;
		997	sub aio_rmtree($;$) {
		998	my ($path, $cb) = @_;
		999
		1000	my $pri = aioreq_pri;
		1001	my $grp = aio_group $cb;
		1002
		1003	aioreq_pri $pri;
		1004	add $grp aio_scandir $path, 0, sub {
		1005	my ($dirs, $nondirs) = @_;
		1006
		1007	my $dirgrp = aio_group sub {
		1008	add $grp aio_rmdir $path, sub {
		1009	$grp->result ($_[0]);
		1010	};
		1011	};
		1012
		1013	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1014	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1015
		1016	add $grp $dirgrp;
		1017	};
		1018
		1019	$grp
		1020	}
		1021
		1022	=item aio_sync $callback->($status)
		1023
		1024	Asynchronously call sync and call the callback when finished.
		1025
629	=item aio_fsync $fh, $callback->($status)	1026	=item aio_fsync $fh, $callback->($status)
630		1027
631	Asynchronously call fsync on the given filehandle and call the callback	1028	Asynchronously call fsync on the given filehandle and call the callback
632	with the fsync result code.	1029	with the fsync result code.
633		1030
…		…
636	Asynchronously call fdatasync on the given filehandle and call the	1033	Asynchronously call fdatasync on the given filehandle and call the
637	callback with the fdatasync result code.	1034	callback with the fdatasync result code.
638		1035
639	If this call isn't available because your OS lacks it or it couldn't be	1036	If this call isn't available because your OS lacks it or it couldn't be
640	detected, it will be emulated by calling C<fsync> instead.	1037	detected, it will be emulated by calling C<fsync> instead.
		1038
		1039	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1040
		1041	Sync the data portion of the file specified by C<$offset> and C<$length>
		1042	to disk (but NOT the metadata), by calling the Linux-specific
		1043	sync_file_range call. If sync_file_range is not available or it returns
		1044	ENOSYS, then fdatasync or fsync is being substituted.
		1045
		1046	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1047	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1048	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1049	manpage for details.
		1050
		1051	=item aio_pathsync $path, $callback->($status)
		1052
		1053	This request tries to open, fsync and close the given path. This is a
		1054	composite request intended to sync directories after directory operations
		1055	(E.g. rename). This might not work on all operating systems or have any
		1056	specific effect, but usually it makes sure that directory changes get
		1057	written to disc. It works for anything that can be opened for read-only,
		1058	not just directories.
		1059
		1060	Future versions of this function might fall back to other methods when
		1061	C<fsync> on the directory fails (such as calling C<sync>).
		1062
		1063	Passes C<0> when everything went ok, and C<-1> on error.
		1064
		1065	=cut
		1066
		1067	sub aio_pathsync($;$) {
		1068	my ($path, $cb) = @_;
		1069
		1070	my $pri = aioreq_pri;
		1071	my $grp = aio_group $cb;
		1072
		1073	aioreq_pri $pri;
		1074	add $grp aio_open $path, O_RDONLY, 0, sub {
		1075	my ($fh) = @_;
		1076	if ($fh) {
		1077	aioreq_pri $pri;
		1078	add $grp aio_fsync $fh, sub {
		1079	$grp->result ($_[0]);
		1080
		1081	aioreq_pri $pri;
		1082	add $grp aio_close $fh;
		1083	};
		1084	} else {
		1085	$grp->result (-1);
		1086	}
		1087	};
		1088
		1089	$grp
		1090	}
		1091
		1092	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1093
		1094	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1095	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1096	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1097	scalar must only be modified in-place while an aio operation is pending on
		1098	it).
		1099
		1100	It calls the C<msync> function of your OS, if available, with the memory
		1101	area starting at C<$offset> in the string and ending C<$length> bytes
		1102	later. If C<$length> is negative, counts from the end, and if C<$length>
		1103	is C<undef>, then it goes till the end of the string. The flags can be
		1104	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1105	C<IO::AIO::MS_SYNC>.
		1106
		1107	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1108
		1109	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1110	scalars.
		1111
		1112	It touches (reads or writes) all memory pages in the specified
		1113	range inside the scalar. All caveats and parameters are the same
		1114	as for C<aio_msync>, above, except for flags, which must be either
		1115	C<0> (which reads all pages and ensures they are instantiated) or
		1116	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1117	writing an octet from it, which dirties the page).
		1118
		1119	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1120
		1121	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1122	scalars.
		1123
		1124	It reads in all the pages of the underlying storage into memory (if any)
		1125	and locks them, so they are not getting swapped/paged out or removed.
		1126
		1127	If C<$length> is undefined, then the scalar will be locked till the end.
		1128
		1129	On systems that do not implement C<mlock>, this function returns C<-1>
		1130	and sets errno to C<ENOSYS>.
		1131
		1132	Note that the corresponding C<munlock> is synchronous and is
		1133	documented under L<MISCELLANEOUS FUNCTIONS>.
		1134
		1135	Example: open a file, mmap and mlock it - both will be undone when
		1136	C<$data> gets destroyed.
		1137
		1138	open my $fh, "<", $path or die "$path: $!";
		1139	my $data;
		1140	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1141	aio_mlock $data; # mlock in background
		1142
		1143	=item aio_mlockall $flags, $callback->($status)
		1144
		1145	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1146	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1147
		1148	On systems that do not implement C<mlockall>, this function returns C<-1>
		1149	and sets errno to C<ENOSYS>.
		1150
		1151	Note that the corresponding C<munlockall> is synchronous and is
		1152	documented under L<MISCELLANEOUS FUNCTIONS>.
		1153
		1154	Example: asynchronously lock all current and future pages into memory.
		1155
		1156	aio_mlockall IO::AIO::MCL_FUTURE;
641		1157
642	=item aio_group $callback->(...)	1158	=item aio_group $callback->(...)
643		1159
644	This is a very special aio request: Instead of doing something, it is a	1160	This is a very special aio request: Instead of doing something, it is a
645	container for other aio requests, which is useful if you want to bundle	1161	container for other aio requests, which is useful if you want to bundle
…		…
695	=item cancel $req	1211	=item cancel $req
696		1212
697	Cancels the request, if possible. Has the effect of skipping execution	1213	Cancels the request, if possible. Has the effect of skipping execution
698	when entering the B<execute> state and skipping calling the callback when	1214	when entering the B<execute> state and skipping calling the callback when
699	entering the the B<result> state, but will leave the request otherwise	1215	entering the the B<result> state, but will leave the request otherwise
700	untouched. That means that requests that currently execute will not be	1216	untouched (with the exception of readdir). That means that requests that
701	stopped and resources held by the request will not be freed prematurely.	1217	currently execute will not be stopped and resources held by the request
		1218	will not be freed prematurely.
702		1219
703	=item cb $req $callback->(...)	1220	=item cb $req $callback->(...)
704		1221
705	Replace (or simply set) the callback registered to the request.	1222	Replace (or simply set) the callback registered to the request.
706		1223
…		…
757	Their lifetime, simplified, looks like this: when they are empty, they	1274	Their lifetime, simplified, looks like this: when they are empty, they
758	will finish very quickly. If they contain only requests that are in the	1275	will finish very quickly. If they contain only requests that are in the
759	C<done> state, they will also finish. Otherwise they will continue to	1276	C<done> state, they will also finish. Otherwise they will continue to
760	exist.	1277	exist.
761		1278
762	That means after creating a group you have some time to add requests. And	1279	That means after creating a group you have some time to add requests
763	in the callbacks of those requests, you can add further requests to the	1280	(precisely before the callback has been invoked, which is only done within
764	group. And only when all those requests have finished will the the group	1281	the C<poll_cb>). And in the callbacks of those requests, you can add
765	itself finish.	1282	further requests to the group. And only when all those requests have
		1283	finished will the the group itself finish.
766		1284
767	=over 4	1285	=over 4
768		1286
769	=item add $grp ...	1287	=item add $grp ...
770		1288
…		…
779	=item $grp->cancel_subs	1297	=item $grp->cancel_subs
780		1298
781	Cancel all subrequests and clears any feeder, but not the group request	1299	Cancel all subrequests and clears any feeder, but not the group request
782	itself. Useful when you queued a lot of events but got a result early.	1300	itself. Useful when you queued a lot of events but got a result early.
783		1301
		1302	The group request will finish normally (you cannot add requests to the
		1303	group).
		1304
784	=item $grp->result (...)	1305	=item $grp->result (...)
785		1306
786	Set the result value(s) that will be passed to the group callback when all	1307	Set the result value(s) that will be passed to the group callback when all
787	subrequests have finished and set thre groups errno to the current value	1308	subrequests have finished and set the groups errno to the current value
788	of errno (just like calling C<errno> without an error number). By default,	1309	of errno (just like calling C<errno> without an error number). By default,
789	no argument will be passed and errno is zero.	1310	no argument will be passed and errno is zero.
790		1311
791	=item $grp->errno ([$errno])	1312	=item $grp->errno ([$errno])
792		1313
…		…
803	=item feed $grp $callback->($grp)	1324	=item feed $grp $callback->($grp)
804		1325
805	Sets a feeder/generator on this group: every group can have an attached	1326	Sets a feeder/generator on this group: every group can have an attached
806	generator that generates requests if idle. The idea behind this is that,	1327	generator that generates requests if idle. The idea behind this is that,
807	although you could just queue as many requests as you want in a group,	1328	although you could just queue as many requests as you want in a group,
808	this might starve other requests for a potentially long time. For	1329	this might starve other requests for a potentially long time. For example,
809	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1330	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
810	requests, delaying any later requests for a long time.	1331	delaying any later requests for a long time.
811		1332
812	To avoid this, and allow incremental generation of requests, you can	1333	To avoid this, and allow incremental generation of requests, you can
813	instead a group and set a feeder on it that generates those requests. The	1334	instead a group and set a feeder on it that generates those requests. The
814	feed callback will be called whenever there are few enough (see C<limit>,	1335	feed callback will be called whenever there are few enough (see C<limit>,
815	below) requests active in the group itself and is expected to queue more	1336	below) requests active in the group itself and is expected to queue more
…		…
819	not impose any limits).	1340	not impose any limits).
820		1341
821	If the feed does not queue more requests when called, it will be	1342	If the feed does not queue more requests when called, it will be
822	automatically removed from the group.	1343	automatically removed from the group.
823		1344
824	If the feed limit is C<0>, it will be set to C<2> automatically.	1345	If the feed limit is C<0> when this method is called, it will be set to
		1346	C<2> automatically.
825		1347
826	Example:	1348	Example:
827		1349
828	# stat all files in @files, but only ever use four aio requests concurrently:	1350	# stat all files in @files, but only ever use four aio requests concurrently:
829		1351
…		…
841	Sets the feeder limit for the group: The feeder will be called whenever	1363	Sets the feeder limit for the group: The feeder will be called whenever
842	the group contains less than this many requests.	1364	the group contains less than this many requests.
843		1365
844	Setting the limit to C<0> will pause the feeding process.	1366	Setting the limit to C<0> will pause the feeding process.
845		1367
		1368	The default value for the limit is C<0>, but note that setting a feeder
		1369	automatically bumps it up to C<2>.
		1370
846	=back	1371	=back
847		1372
848	=head2 SUPPORT FUNCTIONS	1373	=head2 SUPPORT FUNCTIONS
849		1374
		1375	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1376
850	=over 4	1377	=over 4
851		1378
852	=item $fileno = IO::AIO::poll_fileno	1379	=item $fileno = IO::AIO::poll_fileno
853		1380
854	Return the I<request result pipe file descriptor>. This filehandle must be	1381	Return the I<request result pipe file descriptor>. This filehandle must be
855	polled for reading by some mechanism outside this module (e.g. Event or	1382	polled for reading by some mechanism outside this module (e.g. EV, Glib,
856	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1383	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
857	to call C<poll_cb> to check the results.	1384	you have to call C<poll_cb> to check the results.
858		1385
859	See C<poll_cb> for an example.	1386	See C<poll_cb> for an example.
860		1387
861	=item IO::AIO::poll_cb	1388	=item IO::AIO::poll_cb
862		1389
863	Process all outstanding events on the result pipe. You have to call this	1390	Process some outstanding events on the result pipe. You have to call this
864	regularly. Returns the number of events processed. Returns immediately	1391	regularly. Returns C<0> if all events could be processed, or C<-1> if it
865	when no events are outstanding.	1392	returned earlier for whatever reason. Returns immediately when no events
		1393	are outstanding. The amount of events processed depends on the settings of
		1394	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
866		1395
867	If not all requests were processed for whatever reason, the filehandle	1396	If not all requests were processed for whatever reason, the filehandle
868	will still be ready when C<poll_cb> returns.	1397	will still be ready when C<poll_cb> returns, so normally you don't have to
		1398	do anything special to have it called later.
869		1399
870	Example: Install an Event watcher that automatically calls	1400	Example: Install an Event watcher that automatically calls
871	IO::AIO::poll_cb with high priority:	1401	IO::AIO::poll_cb with high priority (more examples can be found in the
		1402	SYNOPSIS section, at the top of this document):
872		1403
873	Event->io (fd => IO::AIO::poll_fileno,	1404	Event->io (fd => IO::AIO::poll_fileno,
874	poll => 'r', async => 1,	1405	poll => 'r', async => 1,
875	cb => \&IO::AIO::poll_cb);	1406	cb => \&IO::AIO::poll_cb);
876		1407
877	=item IO::AIO::poll_some $max_requests	1408	=item IO::AIO::poll_wait
878		1409
879	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests	1410	If there are any outstanding requests and none of them in the result
880	at a time.	1411	phase, wait till the result filehandle becomes ready for reading (simply
		1412	does a C<select> on the filehandle. This is useful if you want to
		1413	synchronously wait for some requests to finish).
881		1414
882	Useful if you want to ensure some level of interactiveness when perl is	1415	See C<nreqs> for an example.
883	not fast enough to process all requests in time.	1416
		1417	=item IO::AIO::poll
		1418
		1419	Waits until some requests have been handled.
		1420
		1421	Returns the number of requests processed, but is otherwise strictly
		1422	equivalent to:
		1423
		1424	IO::AIO::poll_wait, IO::AIO::poll_cb
		1425
		1426	=item IO::AIO::flush
		1427
		1428	Wait till all outstanding AIO requests have been handled.
		1429
		1430	Strictly equivalent to:
		1431
		1432	IO::AIO::poll_wait, IO::AIO::poll_cb
		1433	while IO::AIO::nreqs;
		1434
		1435	=item IO::AIO::max_poll_reqs $nreqs
		1436
		1437	=item IO::AIO::max_poll_time $seconds
		1438
		1439	These set the maximum number of requests (default C<0>, meaning infinity)
		1440	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1441	the maximum amount of time (default C<0>, meaning infinity) spent in
		1442	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1443	of time C<poll_cb> is allowed to use).
		1444
		1445	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1446	syscall per request processed, which is not normally a problem unless your
		1447	callbacks are really really fast or your OS is really really slow (I am
		1448	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1449
		1450	Setting these is useful if you want to ensure some level of
		1451	interactiveness when perl is not fast enough to process all requests in
		1452	time.
		1453
		1454	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
884		1455
885	Example: Install an Event watcher that automatically calls	1456	Example: Install an Event watcher that automatically calls
886	IO::AIO::poll_some with low priority, to ensure that other parts of the	1457	IO::AIO::poll_cb with low priority, to ensure that other parts of the
887	program get the CPU sometimes even under high AIO load.	1458	program get the CPU sometimes even under high AIO load.
888		1459
		1460	# try not to spend much more than 0.1s in poll_cb
		1461	IO::AIO::max_poll_time 0.1;
		1462
		1463	# use a low priority so other tasks have priority
889	Event->io (fd => IO::AIO::poll_fileno,	1464	Event->io (fd => IO::AIO::poll_fileno,
890	poll => 'r', nice => 1,	1465	poll => 'r', nice => 1,
891	cb => sub { IO::AIO::poll_some 256 });	1466	cb => &IO::AIO::poll_cb);
892		1467
893	=item IO::AIO::poll_wait	1468	=back
894		1469
895	Wait till the result filehandle becomes ready for reading (simply does a	1470	=head3 CONTROLLING THE NUMBER OF THREADS
896	C<select> on the filehandle. This is useful if you want to synchronously wait
897	for some requests to finish).
898		1471
899	See C<nreqs> for an example.	1472	=over
900
901	=item IO::AIO::nreqs
902
903	Returns the number of requests currently in the ready, execute or pending
904	states (i.e. for which their callback has not been invoked yet).
905
906	Example: wait till there are no outstanding requests anymore:
907
908	IO::AIO::poll_wait, IO::AIO::poll_cb
909	while IO::AIO::nreqs;
910
911	=item IO::AIO::nready
912
913	Returns the number of requests currently in the ready state (not yet
914	executed).
915
916	=item IO::AIO::npending
917
918	Returns the number of requests currently in the pending state (executed,
919	but not yet processed by poll_cb).
920
921	=item IO::AIO::flush
922
923	Wait till all outstanding AIO requests have been handled.
924
925	Strictly equivalent to:
926
927	IO::AIO::poll_wait, IO::AIO::poll_cb
928	while IO::AIO::nreqs;
929
930	=item IO::AIO::poll
931
932	Waits until some requests have been handled.
933
934	Strictly equivalent to:
935
936	IO::AIO::poll_wait, IO::AIO::poll_cb
937	if IO::AIO::nreqs;
938		1473
939	=item IO::AIO::min_parallel $nthreads	1474	=item IO::AIO::min_parallel $nthreads
940		1475
941	Set the minimum number of AIO threads to C<$nthreads>. The current	1476	Set the minimum number of AIO threads to C<$nthreads>. The current
942	default is C<8>, which means eight asynchronous operations can execute	1477	default is C<8>, which means eight asynchronous operations can execute
943	concurrently at any one time (the number of outstanding requests,	1478	concurrently at any one time (the number of outstanding requests,
944	however, is unlimited).	1479	however, is unlimited).
945		1480
946	IO::AIO starts threads only on demand, when an AIO request is queued and	1481	IO::AIO starts threads only on demand, when an AIO request is queued and
947	no free thread exists.	1482	no free thread exists. Please note that queueing up a hundred requests can
		1483	create demand for a hundred threads, even if it turns out that everything
		1484	is in the cache and could have been processed faster by a single thread.
948		1485
949	It is recommended to keep the number of threads relatively low, as some	1486	It is recommended to keep the number of threads relatively low, as some
950	Linux kernel versions will scale negatively with the number of threads	1487	Linux kernel versions will scale negatively with the number of threads
951	(higher parallelity => MUCH higher latency). With current Linux 2.6	1488	(higher parallelity => MUCH higher latency). With current Linux 2.6
952	versions, 4-32 threads should be fine.	1489	versions, 4-32 threads should be fine.
…		…
966	This module automatically runs C<max_parallel 0> at program end, to ensure	1503	This module automatically runs C<max_parallel 0> at program end, to ensure
967	that all threads are killed and that there are no outstanding requests.	1504	that all threads are killed and that there are no outstanding requests.
968		1505
969	Under normal circumstances you don't need to call this function.	1506	Under normal circumstances you don't need to call this function.
970		1507
		1508	=item IO::AIO::max_idle $nthreads
		1509
		1510	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1511	threads that did not get a request to process within 10 seconds). That
		1512	means if a thread becomes idle while C<$nthreads> other threads are also
		1513	idle, it will free its resources and exit.
		1514
		1515	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1516	to allow for extremely high load situations, but want to free resources
		1517	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1518
		1519	The default is probably ok in most situations, especially if thread
		1520	creation is fast. If thread creation is very slow on your system you might
		1521	want to use larger values.
		1522
971	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1523	=item IO::AIO::max_outstanding $maxreqs
972		1524
973	This is a very bad function to use in interactive programs because it	1525	This is a very bad function to use in interactive programs because it
974	blocks, and a bad way to reduce concurrency because it is inexact: Better	1526	blocks, and a bad way to reduce concurrency because it is inexact: Better
975	use an C<aio_group> together with a feed callback.	1527	use an C<aio_group> together with a feed callback.
976		1528
977	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1529	Sets the maximum number of outstanding requests to C<$nreqs>. If you
978	to queue up more than this number of requests, the next call to the	1530	do queue up more than this number of requests, the next call to the
979	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)	1531	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
980	function will block until the limit is no longer exceeded.	1532	function will block until the limit is no longer exceeded.
981		1533
982	The default value is very large, so there is no practical limit on the	1534	The default value is very large, so there is no practical limit on the
983	number of outstanding requests.	1535	number of outstanding requests.
984		1536
985	You can still queue as many requests as you want. Therefore,	1537	You can still queue as many requests as you want. Therefore,
986	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	1538	C<max_outstanding> is mainly useful in simple scripts (with low values) or
987	as a stop gap to shield against fatal memory overflow (with large values).	1539	as a stop gap to shield against fatal memory overflow (with large values).
988		1540
989	=back	1541	=back
990		1542
		1543	=head3 STATISTICAL INFORMATION
		1544
		1545	=over
		1546
		1547	=item IO::AIO::nreqs
		1548
		1549	Returns the number of requests currently in the ready, execute or pending
		1550	states (i.e. for which their callback has not been invoked yet).
		1551
		1552	Example: wait till there are no outstanding requests anymore:
		1553
		1554	IO::AIO::poll_wait, IO::AIO::poll_cb
		1555	while IO::AIO::nreqs;
		1556
		1557	=item IO::AIO::nready
		1558
		1559	Returns the number of requests currently in the ready state (not yet
		1560	executed).
		1561
		1562	=item IO::AIO::npending
		1563
		1564	Returns the number of requests currently in the pending state (executed,
		1565	but not yet processed by poll_cb).
		1566
		1567	=back
		1568
		1569	=head3 MISCELLANEOUS FUNCTIONS
		1570
		1571	IO::AIO implements some functions that might be useful, but are not
		1572	asynchronous.
		1573
		1574	=over 4
		1575
		1576	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1577
		1578	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1579	but is blocking (this makes most sense if you know the input data is
		1580	likely cached already and the output filehandle is set to non-blocking
		1581	operations).
		1582
		1583	Returns the number of bytes copied, or C<-1> on error.
		1584
		1585	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1586
		1587	Simply calls the C<posix_fadvise> function (see its
		1588	manpage for details). The following advice constants are
		1589	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1590	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1591	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1592
		1593	On systems that do not implement C<posix_fadvise>, this function returns
		1594	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1595
		1596	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1597
		1598	Simply calls the C<posix_madvise> function (see its
		1599	manpage for details). The following advice constants are
		1600	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1601	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1602
		1603	On systems that do not implement C<posix_madvise>, this function returns
		1604	ENOSYS, otherwise the return value of C<posix_madvise>.
		1605
		1606	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1607
		1608	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1609	$scalar (see its manpage for details). The following protect
		1610	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1611	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1612
		1613	On systems that do not implement C<mprotect>, this function returns
		1614	ENOSYS, otherwise the return value of C<mprotect>.
		1615
		1616	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1617
		1618	Memory-maps a file (or anonymous memory range) and attaches it to the
		1619	given C<$scalar>, which will act like a string scalar.
		1620
		1621	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1622	change the string length, and most read-only operations such as copying it
		1623	or searching it with regexes and so on.
		1624
		1625	Anything else is unsafe and will, at best, result in memory leaks.
		1626
		1627	The memory map associated with the C<$scalar> is automatically removed
		1628	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1629	C<IO::AIO::munmap> functions are called.
		1630
		1631	This calls the C<mmap>(2) function internally. See your system's manual
		1632	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1633
		1634	The C<$length> must be larger than zero and smaller than the actual
		1635	filesize.
		1636
		1637	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1638	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1639
		1640	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1641	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1642	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1643	(which is set to C<MAP_ANON> if your system only provides this
		1644	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1645	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1646	C<IO::AIO::MAP_NONBLOCK>
		1647
		1648	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1649
		1650	C<$offset> is the offset from the start of the file - it generally must be
		1651	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1652
		1653	Example:
		1654
		1655	use Digest::MD5;
		1656	use IO::AIO;
		1657
		1658	open my $fh, "<verybigfile"
		1659	or die "$!";
		1660
		1661	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1662	or die "verybigfile: $!";
		1663
		1664	my $fast_md5 = md5 $data;
		1665
		1666	=item IO::AIO::munmap $scalar
		1667
		1668	Removes a previous mmap and undefines the C<$scalar>.
		1669
		1670	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1671
		1672	Calls the C<munlock> function, undoing the effects of a previous
		1673	C<aio_mlock> call (see its description for details).
		1674
		1675	=item IO::AIO::munlockall
		1676
		1677	Calls the C<munlockall> function.
		1678
		1679	On systems that do not implement C<munlockall>, this function returns
		1680	ENOSYS, otherwise the return value of C<munlockall>.
		1681
		1682	=back
		1683
991	=cut	1684	=cut
992		1685
993	# support function to convert a fd into a perl filehandle
994	sub _fd2fh {
995	return undef if $_[0] < 0;
996
997	# try to generate nice filehandles
998	my $sym = "IO::AIO::fd#$_[0]";
999	local *$sym;
1000
1001	open *$sym, "+<&=$_[0]" # usually works under any unix
1002	or open *$sym, "<&=$_[0]" # cygwin needs this
1003	or open *$sym, ">&=$_[0]" # or this
1004	or return undef;
1005
1006	*$sym
1007	}
1008
1009	min_parallel 8;	1686	min_parallel 8;
1010		1687
1011	END {	1688	END { flush }
1012	min_parallel 1;
1013	flush;
1014	};
1015		1689
1016	1;	1690	1;
		1691
		1692	=head1 EVENT LOOP INTEGRATION
		1693
		1694	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1695	automatically into many event loops:
		1696
		1697	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1698	use AnyEvent::AIO;
		1699
		1700	You can also integrate IO::AIO manually into many event loops, here are
		1701	some examples of how to do this:
		1702
		1703	# EV integration
		1704	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1705
		1706	# Event integration
		1707	Event->io (fd => IO::AIO::poll_fileno,
		1708	poll => 'r',
		1709	cb => \&IO::AIO::poll_cb);
		1710
		1711	# Glib/Gtk2 integration
		1712	add_watch Glib::IO IO::AIO::poll_fileno,
		1713	in => sub { IO::AIO::poll_cb; 1 };
		1714
		1715	# Tk integration
		1716	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1717	readable => \&IO::AIO::poll_cb);
		1718
		1719	# Danga::Socket integration
		1720	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1721	\&IO::AIO::poll_cb);
1017		1722
1018	=head2 FORK BEHAVIOUR	1723	=head2 FORK BEHAVIOUR
1019		1724
1020	This module should do "the right thing" when the process using it forks:	1725	This module should do "the right thing" when the process using it forks:
1021		1726
…		…
1039	bytes of memory. In addition, stat requests need a stat buffer (possibly	1744	bytes of memory. In addition, stat requests need a stat buffer (possibly
1040	a few hundred bytes), readdir requires a result buffer and so on. Perl	1745	a few hundred bytes), readdir requires a result buffer and so on. Perl
1041	scalars and other data passed into aio requests will also be locked and	1746	scalars and other data passed into aio requests will also be locked and
1042	will consume memory till the request has entered the done state.	1747	will consume memory till the request has entered the done state.
1043		1748
1044	This is now awfully much, so queuing lots of requests is not usually a	1749	This is not awfully much, so queuing lots of requests is not usually a
1045	problem.	1750	problem.
1046		1751
1047	Per-thread usage:	1752	Per-thread usage:
1048		1753
1049	In the execution phase, some aio requests require more memory for	1754	In the execution phase, some aio requests require more memory for
…		…
1054		1759
1055	Known bugs will be fixed in the next release.	1760	Known bugs will be fixed in the next release.
1056		1761
1057	=head1 SEE ALSO	1762	=head1 SEE ALSO
1058		1763
1059	L<Coro::AIO>.	1764	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1765	more natural syntax.
1060		1766
1061	=head1 AUTHOR	1767	=head1 AUTHOR
1062		1768
1063	Marc Lehmann <schmorp@schmorp.de>	1769	Marc Lehmann <schmorp@schmorp.de>
1064	http://home.schmorp.de/	1770	http://home.schmorp.de/

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