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Revision 1.82 by root, Fri Oct 27 20:10:06 2006 UTC vs.
Revision 1.185 by root, Sat Dec 11 19:06:07 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>).
		36
		37	Asynchronous means that operations that can normally block your program
		38	(e.g. reading from disk) will be done asynchronously: the operation
		39	will still block, but you can do something else in the meantime. This
		40	is extremely useful for programs that need to stay interactive even
		41	when doing heavy I/O (GUI programs, high performance network servers
		42	etc.), but can also be used to easily do operations in parallel that are
		43	normally done sequentially, e.g. stat'ing many files, which is much faster
		44	on a RAID volume or over NFS when you do a number of stat operations
		45	concurrently.
		46
		47	While most of this works on all types of file descriptors (for
		48	example sockets), using these functions on file descriptors that
		49	support nonblocking operation (again, sockets, pipes etc.) is
		50	very inefficient. Use an event loop for that (such as the L<EV>
		51	module): IO::AIO will naturally fit into such an event loop itself.
55		52
56	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
57	requests and signal their completion. You don't need thread support	54	requests and signal their completion. You don't need thread support
58	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
59	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
60	functions available on many operating systems. However, they are often	57	functions available on many operating systems. However, they are often
61	not well-supported or restricted (Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
62	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
63	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
64	using threads anyway.	61	using threads anyway.
65		62
66	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,
67	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
68	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
69	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;
70		109
71	=head1 REQUEST ANATOMY AND LIFETIME	110	=head1 REQUEST ANATOMY AND LIFETIME
72		111
73	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
74	directly visible to Perl.	113	directly visible to Perl.
…		…
116	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
117	(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
118	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
119	result in a runtime error).	158	result in a runtime error).
120		159
		160	=back
		161
121	=cut	162	=cut
122		163
123	package IO::AIO;	164	package IO::AIO;
124		165
125	no warnings;	166	use Carp ();
126	use strict 'vars';	167
		168	use common::sense;
127		169
128	use base 'Exporter';	170	use base 'Exporter';
129		171
130	BEGIN {	172	BEGIN {
131	our $VERSION = '2.0';	173	our $VERSION = '3.7';
132		174
133	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
134	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
135	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	177	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
136	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
137	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
138	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139	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
140		194
141	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	195	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142		196
143	require XSLoader;	197	require XSLoader;
144	XSLoader::load ("IO::AIO", $VERSION);	198	XSLoader::load ("IO::AIO", $VERSION);
145	}	199	}
146		200
147	=head1 FUNCTIONS	201	=head1 FUNCTIONS
148		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, $length = undef
		273	IO::AIO::munlockall
		274
149	=head2 AIO FUNCTIONS	275	=head2 AIO REQUEST FUNCTIONS
150		276
151	All the C<aio_*> calls are more or less thin wrappers around the syscall	277	All the C<aio_*> calls are more or less thin wrappers around the syscall
152	with the same name (sans C<aio_>). The arguments are similar or identical,	278	with the same name (sans C<aio_>). The arguments are similar or identical,
153	and they all accept an additional (and optional) C<$callback> argument	279	and they all accept an additional (and optional) C<$callback> argument
154	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
155	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
156	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
157	syscall has been executed asynchronously.	283	syscall has been executed asynchronously.
158		284
159	All functions expecting a filehandle keep a copy of the filehandle	285	All functions expecting a filehandle keep a copy of the filehandle
160	internally until the request has finished.	286	internally until the request has finished.
161		287
162	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
163	manipulation of those requests while they are in-flight.	289	further manipulation of those requests while they are in-flight.
164		290
165	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
166	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
167	request is being executed, the current working directory could have	293	request is being executed, the current working directory could have
168	changed. Alternatively, you can make sure that you never change the	294	changed. Alternatively, you can make sure that you never change the
169	current working directory.	295	current working directory anywhere in the program and then use relative
		296	paths.
170		297
171	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
172	always pass in filenames you got from outside (command line, readdir	299	in filenames you got from outside (command line, readdir etc.) without
173	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
174	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
175	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)
176	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.
177		307
178	=over 4	308	=over 4
179		309
180	=item $prev_pri = aioreq_pri [$pri]	310	=item $prev_pri = aioreq_pri [$pri]
181		311
…		…
201	aio_read $_[0], ..., sub {	331	aio_read $_[0], ..., sub {
202	...	332	...
203	};	333	};
204	};	334	};
205		335
		336
206	=item aioreq_nice $pri_adjust	337	=item aioreq_nice $pri_adjust
207		338
208	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
209	priority, so effects are cumulative.	340	priority, so the effect is cumulative.
		341
210		342
211	=item aio_open $pathname, $flags, $mode, $callback->($fh)	343	=item aio_open $pathname, $flags, $mode, $callback->($fh)
212		344
213	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
214	created filehandle for the file.	346	created filehandle for the file.
…		…
220	list. They are the same as used by C<sysopen>.	352	list. They are the same as used by C<sysopen>.
221		353
222	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
223	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>,
224	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,
225	and C<0666> or C<0777> if you do).	357	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		358	by the umask in effect then the request is being executed, so better never
		359	change the umask.
226		360
227	Example:	361	Example:
228		362
229	aio_open "/etc/passwd", O_RDONLY, 0, sub {	363	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
230	if ($_[0]) {	364	if ($_[0]) {
231	print "open successful, fh is $_[0]\n";	365	print "open successful, fh is $_[0]\n";
232	...	366	...
233	} else {	367	} else {
234	die "open failed: $!\n";	368	die "open failed: $!\n";
235	}	369	}
236	};	370	};
237		371
		372
238	=item aio_close $fh, $callback->($status)	373	=item aio_close $fh, $callback->($status)
239		374
240	Asynchronously close a file and call the callback with the result	375	Asynchronously close a file and call the callback with the result
241	code. I<WARNING:> although accepted, you should not pass in a perl	376	code.
242	filehandle here, as perl will likely close the file descriptor another
243	time when the filehandle is destroyed. Normally, you can safely call perls
244	C<close> or just let filehandles go out of scope.
245		377
246	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
247	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
248		389
249	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	390	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
250		391
251	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	392	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
252		393
253	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
254	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<$dataoffset>
255	callback without the actual number of bytes read (or -1 on error, just	396	and calls the callback without the actual number of bytes read (or -1 on
256	like the syscall).	397	error, just like the syscall).
		398
		399	C<aio_read> will, like C<sysread>, shrink or grow the C<$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<$data>.
257		411
258	The C<$data> scalar I<MUST NOT> be modified in any way while the request	412	The C<$data> scalar I<MUST NOT> be modified in any way while the request
259	is outstanding. Modifying it can result in segfaults or WW3 (if the	413	is outstanding. Modifying it can result in segfaults or World War III (if
260	necessary/optional hardware is installed).	414	the necessary/optional hardware is installed).
261		415
262	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	416	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
263	offset C<0> within the scalar:	417	offset C<0> within the scalar:
264		418
265	aio_read $fh, 7, 15, $buffer, 0, sub {	419	aio_read $fh, 7, 15, $buffer, 0, sub {
266	$_[0] > 0 or die "read error: $!";	420	$_[0] > 0 or die "read error: $!";
267	print "read $_[0] bytes: <$buffer>\n";	421	print "read $_[0] bytes: <$buffer>\n";
268	};	422	};
		423
269		424
270	=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)
271		426
272	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
273	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
274	file offset of C<$out_fh>. Because of that, it is not safe to issue more	429	file offset of C<$out_fh>. Because of that, it is not safe to issue more
275	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
276	other.	431	other.
277		432
		433	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		434	are written, and there is no way to find out how many bytes have been read
		435	from C<aio_sendfile> alone, as C<aio_sendfile> only provides the number of
		436	bytes written to C<$out_fh>. Only if the result value equals C<$length>
		437	one can assume that C<$length> bytes have been read.
		438
		439	Unlike with other C<aio_> functions, it makes a lot of sense to use
		440	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		441	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		442	the socket I/O will be non-blocking. Note, however, that you can run into
		443	a trap where C<aio_sendfile> reads some data with readahead, then fails
		444	to write all data, and when the socket is ready the next time, the data
		445	in the cache is already lost, forcing C<aio_sendfile> to again hit the
		446	disk. Explicit C<aio_read> + C<aio_write> let's you control resource usage
		447	much better.
		448
278	This call tries to make use of a native C<sendfile> syscall to provide	449	This call tries to make use of a native C<sendfile> syscall to provide
279	zero-copy operation. For this to work, C<$out_fh> should refer to a	450	zero-copy operation. For this to work, C<$out_fh> should refer to a
280	socket, and C<$in_fh> should refer to mmap'able file.	451	socket, and C<$in_fh> should refer to an mmap'able file.
281		452
282	If the native sendfile call fails or is not implemented, it will be	453	If a native sendfile cannot be found or it fails with C<ENOSYS>,
		454	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,
283	emulated, so you can call C<aio_sendfile> on any type of filehandle	455	it will be emulated, so you can call C<aio_sendfile> on any type of
284	regardless of the limitations of the operating system.	456	filehandle regardless of the limitations of the operating system.
285		457
286	Please note, however, that C<aio_sendfile> can read more bytes from
287	C<$in_fh> than are written, and there is no way to find out how many
288	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
289	provides the number of bytes written to C<$out_fh>. Only if the result
290	value equals C<$length> one can assume that C<$length> bytes have been
291	read.
292		458
293	=item aio_readahead $fh,$offset,$length, $callback->($retval)	459	=item aio_readahead $fh,$offset,$length, $callback->($retval)
294		460
295	C<aio_readahead> populates the page cache with data from a file so that	461	C<aio_readahead> populates the page cache with data from a file so that
296	subsequent reads from that file will not block on disk I/O. The C<$offset>	462	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
302	file. The current file offset of the file is left unchanged.	468	file. The current file offset of the file is left unchanged.
303		469
304	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	470	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
305	emulated by simply reading the data, which would have a similar effect.	471	emulated by simply reading the data, which would have a similar effect.
306		472
		473
307	=item aio_stat $fh_or_path, $callback->($status)	474	=item aio_stat $fh_or_path, $callback->($status)
308		475
309	=item aio_lstat $fh, $callback->($status)	476	=item aio_lstat $fh, $callback->($status)
310		477
311	Works like perl's C<stat> or C<lstat> in void context. The callback will	478	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
324	aio_stat "/etc/passwd", sub {	491	aio_stat "/etc/passwd", sub {
325	$_[0] and die "stat failed: $!";	492	$_[0] and die "stat failed: $!";
326	print "size is ", -s _, "\n";	493	print "size is ", -s _, "\n";
327	};	494	};
328		495
		496
		497	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		498
		499	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		500	whether a file handle or path was passed.
		501
		502	On success, the callback is passed a hash reference with the following
		503	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		504	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		505	is passed.
		506
		507	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		508	C<ST_NOSUID>.
		509
		510	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		511	their correct value when available, or to C<0> on systems that do
		512	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		513	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		514	C<ST_NODIRATIME> and C<ST_RELATIME>.
		515
		516	Example: stat C</wd> and dump out the data if successful.
		517
		518	aio_statvfs "/wd", sub {
		519	my $f = $_[0]
		520	or die "statvfs: $!";
		521
		522	use Data::Dumper;
		523	say Dumper $f;
		524	};
		525
		526	# result:
		527	{
		528	bsize => 1024,
		529	bfree => 4333064312,
		530	blocks => 10253828096,
		531	files => 2050765568,
		532	flag => 4096,
		533	favail => 2042092649,
		534	bavail => 4333064312,
		535	ffree => 2042092649,
		536	namemax => 255,
		537	frsize => 1024,
		538	fsid => 1810
		539	}
		540
		541
		542	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		543
		544	Works like perl's C<utime> function (including the special case of $atime
		545	and $mtime being undef). Fractional times are supported if the underlying
		546	syscalls support them.
		547
		548	When called with a pathname, uses utimes(2) if available, otherwise
		549	utime(2). If called on a file descriptor, uses futimes(2) if available,
		550	otherwise returns ENOSYS, so this is not portable.
		551
		552	Examples:
		553
		554	# set atime and mtime to current time (basically touch(1)):
		555	aio_utime "path", undef, undef;
		556	# set atime to current time and mtime to beginning of the epoch:
		557	aio_utime "path", time, undef; # undef==0
		558
		559
		560	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		561
		562	Works like perl's C<chown> function, except that C<undef> for either $uid
		563	or $gid is being interpreted as "do not change" (but -1 can also be used).
		564
		565	Examples:
		566
		567	# same as "chown root path" in the shell:
		568	aio_chown "path", 0, -1;
		569	# same as above:
		570	aio_chown "path", 0, undef;
		571
		572
		573	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		574
		575	Works like truncate(2) or ftruncate(2).
		576
		577
		578	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		579
		580	Works like perl's C<chmod> function.
		581
		582
329	=item aio_unlink $pathname, $callback->($status)	583	=item aio_unlink $pathname, $callback->($status)
330		584
331	Asynchronously unlink (delete) a file and call the callback with the	585	Asynchronously unlink (delete) a file and call the callback with the
332	result code.	586	result code.
333		587
		588
334	=item aio_mknod $path, $mode, $dev, $callback->($status)	589	=item aio_mknod $path, $mode, $dev, $callback->($status)
335		590
		591	[EXPERIMENTAL]
		592
336	Asynchronously create a device node (or fifo). See mknod(2): the only	593	Asynchronously create a device node (or fifo). See mknod(2).
337	portable value for C<$mode> is C<S_IFIFO> ored with permissions, and C<0>	594
338	for C<$dev>.	595	The only (POSIX-) portable way of calling this function is:
		596
		597	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		598
339		599
340	=item aio_link $srcpath, $dstpath, $callback->($status)	600	=item aio_link $srcpath, $dstpath, $callback->($status)
341		601
342	Asynchronously create a new link to the existing object at C<$srcpath> at	602	Asynchronously create a new link to the existing object at C<$srcpath> at
343	the path C<$dstpath> and call the callback with the result code.	603	the path C<$dstpath> and call the callback with the result code.
344		604
		605
345	=item aio_symlink $srcpath, $dstpath, $callback->($status)	606	=item aio_symlink $srcpath, $dstpath, $callback->($status)
346		607
347	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	608	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
348	the path C<$dstpath> and call the callback with the result code.	609	the path C<$dstpath> and call the callback with the result code.
349		610
		611
		612	=item aio_readlink $path, $callback->($link)
		613
		614	Asynchronously read the symlink specified by C<$path> and pass it to
		615	the callback. If an error occurs, nothing or undef gets passed to the
		616	callback.
		617
		618
350	=item aio_rename $srcpath, $dstpath, $callback->($status)	619	=item aio_rename $srcpath, $dstpath, $callback->($status)
351		620
352	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	621	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
353	rename(2) and call the callback with the result code.	622	rename(2) and call the callback with the result code.
354		623
		624
		625	=item aio_mkdir $pathname, $mode, $callback->($status)
		626
		627	Asynchronously mkdir (create) a directory and call the callback with
		628	the result code. C<$mode> will be modified by the umask at the time the
		629	request is executed, so do not change your umask.
		630
		631
355	=item aio_rmdir $pathname, $callback->($status)	632	=item aio_rmdir $pathname, $callback->($status)
356		633
357	Asynchronously rmdir (delete) a directory and call the callback with the	634	Asynchronously rmdir (delete) a directory and call the callback with the
358	result code.	635	result code.
		636
359		637
360	=item aio_readdir $pathname, $callback->($entries)	638	=item aio_readdir $pathname, $callback->($entries)
361		639
362	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	640	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
363	directory (i.e. opendir + readdir + closedir). The entries will not be	641	directory (i.e. opendir + readdir + closedir). The entries will not be
364	sorted, and will B<NOT> include the C<.> and C<..> entries.	642	sorted, and will B<NOT> include the C<.> and C<..> entries.
365		643
366	The callback a single argument which is either C<undef> or an array-ref	644	The callback is passed a single argument which is either C<undef> or an
367	with the filenames.	645	array-ref with the filenames.
		646
		647
		648	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		649
		650	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		651	behaviour and output format. In case of an error, C<$entries> will be
		652	C<undef>.
		653
		654	The flags are a combination of the following constants, ORed together (the
		655	flags will also be passed to the callback, possibly modified):
		656
		657	=over 4
		658
		659	=item IO::AIO::READDIR_DENTS
		660
		661	When this flag is off, then the callback gets an arrayref with of names
		662	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		663	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		664	entry in more detail.
		665
		666	C<$name> is the name of the entry.
		667
		668	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		669
		670	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		671	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		672	C<IO::AIO::DT_WHT>.
		673
		674	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		675	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		676	scalars are read-only: you can not modify them.
		677
		678	C<$inode> is the inode number (which might not be exact on systems with 64
		679	bit inode numbers and 32 bit perls). This field has unspecified content on
		680	systems that do not deliver the inode information.
		681
		682	=item IO::AIO::READDIR_DIRS_FIRST
		683
		684	When this flag is set, then the names will be returned in an order where
		685	likely directories come first. This is useful when you need to quickly
		686	find directories, or you want to find all directories while avoiding to
		687	stat() each entry.
		688
		689	If the system returns type information in readdir, then this is used
		690	to find directories directly. Otherwise, likely directories are files
		691	beginning with ".", or otherwise files with no dots, of which files with
		692	short names are tried first.
		693
		694	=item IO::AIO::READDIR_STAT_ORDER
		695
		696	When this flag is set, then the names will be returned in an order
		697	suitable for stat()'ing each one. That is, when you plan to stat()
		698	all files in the given directory, then the returned order will likely
		699	be fastest.
		700
		701	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		702	the likely dirs come first, resulting in a less optimal stat order.
		703
		704	=item IO::AIO::READDIR_FOUND_UNKNOWN
		705
		706	This flag should not be set when calling C<aio_readdirx>. Instead, it
		707	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		708	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		709	C<$type>'s are known, which can be used to speed up some algorithms.
		710
		711	=back
		712
		713
		714	=item aio_load $path, $data, $callback->($status)
		715
		716	This is a composite request that tries to fully load the given file into
		717	memory. Status is the same as with aio_read.
		718
		719	=cut
		720
		721	sub aio_load($$;$) {
		722	my ($path, undef, $cb) = @_;
		723	my $data = \$_[1];
		724
		725	my $pri = aioreq_pri;
		726	my $grp = aio_group $cb;
		727
		728	aioreq_pri $pri;
		729	add $grp aio_open $path, O_RDONLY, 0, sub {
		730	my $fh = shift
		731	or return $grp->result (-1);
		732
		733	aioreq_pri $pri;
		734	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		735	$grp->result ($_[0]);
		736	};
		737	};
		738
		739	$grp
		740	}
368		741
369	=item aio_copy $srcpath, $dstpath, $callback->($status)	742	=item aio_copy $srcpath, $dstpath, $callback->($status)
370		743
371	Try to copy the I<file> (directories not supported as either source or	744	Try to copy the I<file> (directories not supported as either source or
372	destination) from C<$srcpath> to C<$dstpath> and call the callback with	745	destination) from C<$srcpath> to C<$dstpath> and call the callback with
373	the C<0> (error) or C<-1> ok.	746	a status of C<0> (ok) or C<-1> (error, see C<$!>).
374		747
375	This is a composite request that it creates the destination file with	748	This is a composite request that creates the destination file with
376	mode 0200 and copies the contents of the source file into it using	749	mode 0200 and copies the contents of the source file into it using
377	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	750	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
378	uid/gid, in that order.	751	uid/gid, in that order.
379		752
380	If an error occurs, the partial destination file will be unlinked, if	753	If an error occurs, the partial destination file will be unlinked, if
…		…
390	my $grp = aio_group $cb;	763	my $grp = aio_group $cb;
391		764
392	aioreq_pri $pri;	765	aioreq_pri $pri;
393	add $grp aio_open $src, O_RDONLY, 0, sub {	766	add $grp aio_open $src, O_RDONLY, 0, sub {
394	if (my $src_fh = $_[0]) {	767	if (my $src_fh = $_[0]) {
395	my @stat = stat $src_fh;	768	my @stat = stat $src_fh; # hmm, might block over nfs?
396		769
397	aioreq_pri $pri;	770	aioreq_pri $pri;
398	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	771	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
399	if (my $dst_fh = $_[0]) {	772	if (my $dst_fh = $_[0]) {
400	aioreq_pri $pri;	773	aioreq_pri $pri;
401	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	774	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
402	if ($_[0] == $stat[7]) {	775	if ($_[0] == $stat[7]) {
403	$grp->result (0);	776	$grp->result (0);
404	close $src_fh;	777	close $src_fh;
405		778
406	# those should not normally block. should. should.	779	my $ch = sub {
		780	aioreq_pri $pri;
		781	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		782	aioreq_pri $pri;
		783	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		784	aioreq_pri $pri;
		785	add $grp aio_close $dst_fh;
		786	}
		787	};
		788	};
		789
		790	aioreq_pri $pri;
		791	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		792	if ($_[0] < 0 && $! == ENOSYS) {
		793	aioreq_pri $pri;
407	utime $stat[8], $stat[9], $dst;	794	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
408	chmod $stat[2] & 07777, $dst_fh;	795	} else {
409	chown $stat[4], $stat[5], $dst_fh;	796	$ch->();
		797	}
410	close $dst_fh;	798	};
411	} else {	799	} else {
412	$grp->result (-1);	800	$grp->result (-1);
413	close $src_fh;	801	close $src_fh;
414	close $dst_fh;	802	close $dst_fh;
415		803
…		…
432		820
433	=item aio_move $srcpath, $dstpath, $callback->($status)	821	=item aio_move $srcpath, $dstpath, $callback->($status)
434		822
435	Try to move the I<file> (directories not supported as either source or	823	Try to move the I<file> (directories not supported as either source or
436	destination) from C<$srcpath> to C<$dstpath> and call the callback with	824	destination) from C<$srcpath> to C<$dstpath> and call the callback with
437	the C<0> (error) or C<-1> ok.	825	a status of C<0> (ok) or C<-1> (error, see C<$!>).
438		826
439	This is a composite request that tries to rename(2) the file first. If	827	This is a composite request that tries to rename(2) the file first; if
440	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if	828	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
441	that is successful, unlinking the C<$srcpath>.	829	that is successful, unlinks the C<$srcpath>.
442		830
443	=cut	831	=cut
444		832
445	sub aio_move($$;$) {	833	sub aio_move($$;$) {
446	my ($src, $dst, $cb) = @_;	834	my ($src, $dst, $cb) = @_;
…		…
493		881
494	Implementation notes.	882	Implementation notes.
495		883
496	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	884	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
497		885
		886	If readdir returns file type information, then this is used directly to
		887	find directories.
		888
498	After reading the directory, the modification time, size etc. of the	889	Otherwise, after reading the directory, the modification time, size etc.
499	directory before and after the readdir is checked, and if they match (and	890	of the directory before and after the readdir is checked, and if they
500	isn't the current time), the link count will be used to decide how many	891	match (and isn't the current time), the link count will be used to decide
501	entries are directories (if >= 2). Otherwise, no knowledge of the number	892	how many entries are directories (if >= 2). Otherwise, no knowledge of the
502	of subdirectories will be assumed.	893	number of subdirectories will be assumed.
503		894
504	Then entries will be sorted into likely directories (everything without	895	Then entries will be sorted into likely directories a non-initial dot
505	a non-initial dot currently) and likely non-directories (everything	896	currently) and likely non-directories (see C<aio_readdirx>). Then every
506	else). Then every entry plus an appended C</.> will be C<stat>'ed,	897	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
507	likely directories first. If that succeeds, it assumes that the entry	898	in order of their inode numbers. If that succeeds, it assumes that the
508	is a directory or a symlink to directory (which will be checked	899	entry is a directory or a symlink to directory (which will be checked
509	seperately). This is often faster than stat'ing the entry itself because	900	seperately). This is often faster than stat'ing the entry itself because
510	filesystems might detect the type of the entry without reading the inode	901	filesystems might detect the type of the entry without reading the inode
511	data (e.g. ext2fs filetype feature).	902	data (e.g. ext2fs filetype feature), even on systems that cannot return
		903	the filetype information on readdir.
512		904
513	If the known number of directories (link count - 2) has been reached, the	905	If the known number of directories (link count - 2) has been reached, the
514	rest of the entries is assumed to be non-directories.	906	rest of the entries is assumed to be non-directories.
515		907
516	This only works with certainty on POSIX (= UNIX) filesystems, which	908	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
520	as those tend to return 0 or 1 as link counts, which disables the	912	as those tend to return 0 or 1 as link counts, which disables the
521	directory counting heuristic.	913	directory counting heuristic.
522		914
523	=cut	915	=cut
524		916
525	sub aio_scandir($$$) {	917	sub aio_scandir($$;$) {
526	my ($path, $maxreq, $cb) = @_;	918	my ($path, $maxreq, $cb) = @_;
527		919
528	my $pri = aioreq_pri;	920	my $pri = aioreq_pri;
529		921
530	my $grp = aio_group $cb;	922	my $grp = aio_group $cb;
…		…
538	my $now = time;	930	my $now = time;
539	my $hash1 = join ":", (stat _)[0,1,3,7,9];	931	my $hash1 = join ":", (stat _)[0,1,3,7,9];
540		932
541	# read the directory entries	933	# read the directory entries
542	aioreq_pri $pri;	934	aioreq_pri $pri;
543	add $grp aio_readdir $path, sub {	935	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
544	my $entries = shift	936	my $entries = shift
545	or return $grp->result ();	937	or return $grp->result ();
546		938
547	# stat the dir another time	939	# stat the dir another time
548	aioreq_pri $pri;	940	aioreq_pri $pri;
…		…
554	# take the slow route if anything looks fishy	946	# take the slow route if anything looks fishy
555	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	947	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
556	$ndirs = -1;	948	$ndirs = -1;
557	} else {	949	} else {
558	# if nlink == 2, we are finished	950	# if nlink == 2, we are finished
559	# on non-posix-fs's, we rely on nlink < 2	951	# for non-posix-fs's, we rely on nlink < 2
560	$ndirs = (stat _)[3] - 2	952	$ndirs = (stat _)[3] - 2
561	or return $grp->result ([], $entries);	953	or return $grp->result ([], $entries);
562	}	954	}
563		955
564	# sort into likely dirs and likely nondirs
565	# dirs == files without ".", short entries first
566	$entries = [map $_->[0],
567	sort { $b->[1] cmp $a->[1] }
568	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
569	@$entries];
570
571	my (@dirs, @nondirs);	956	my (@dirs, @nondirs);
572		957
573	my $statgrp = add $grp aio_group sub {	958	my $statgrp = add $grp aio_group sub {
574	$grp->result (\@dirs, \@nondirs);	959	$grp->result (\@dirs, \@nondirs);
575	};	960	};
576		961
577	limit $statgrp $maxreq;	962	limit $statgrp $maxreq;
578	feed $statgrp sub {	963	feed $statgrp sub {
579	return unless @$entries;	964	return unless @$entries;
580	my $entry = pop @$entries;	965	my $entry = shift @$entries;
581		966
582	aioreq_pri $pri;	967	aioreq_pri $pri;
583	add $statgrp aio_stat "$path/$entry/.", sub {	968	add $statgrp aio_stat "$path/$entry/.", sub {
584	if ($_[0] < 0) {	969	if ($_[0] < 0) {
585	push @nondirs, $entry;	970	push @nondirs, $entry;
…		…
606	};	991	};
607		992
608	$grp	993	$grp
609	}	994	}
610		995
		996	=item aio_rmtree $path, $callback->($status)
		997
		998	Delete a directory tree starting (and including) C<$path>, return the
		999	status of the final C<rmdir> only. This is a composite request that
		1000	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		1001	everything else.
		1002
		1003	=cut
		1004
		1005	sub aio_rmtree;
		1006	sub aio_rmtree($;$) {
		1007	my ($path, $cb) = @_;
		1008
		1009	my $pri = aioreq_pri;
		1010	my $grp = aio_group $cb;
		1011
		1012	aioreq_pri $pri;
		1013	add $grp aio_scandir $path, 0, sub {
		1014	my ($dirs, $nondirs) = @_;
		1015
		1016	my $dirgrp = aio_group sub {
		1017	add $grp aio_rmdir $path, sub {
		1018	$grp->result ($_[0]);
		1019	};
		1020	};
		1021
		1022	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1023	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1024
		1025	add $grp $dirgrp;
		1026	};
		1027
		1028	$grp
		1029	}
		1030
		1031	=item aio_sync $callback->($status)
		1032
		1033	Asynchronously call sync and call the callback when finished.
		1034
611	=item aio_fsync $fh, $callback->($status)	1035	=item aio_fsync $fh, $callback->($status)
612		1036
613	Asynchronously call fsync on the given filehandle and call the callback	1037	Asynchronously call fsync on the given filehandle and call the callback
614	with the fsync result code.	1038	with the fsync result code.
615		1039
…		…
618	Asynchronously call fdatasync on the given filehandle and call the	1042	Asynchronously call fdatasync on the given filehandle and call the
619	callback with the fdatasync result code.	1043	callback with the fdatasync result code.
620		1044
621	If this call isn't available because your OS lacks it or it couldn't be	1045	If this call isn't available because your OS lacks it or it couldn't be
622	detected, it will be emulated by calling C<fsync> instead.	1046	detected, it will be emulated by calling C<fsync> instead.
		1047
		1048	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1049
		1050	Sync the data portion of the file specified by C<$offset> and C<$length>
		1051	to disk (but NOT the metadata), by calling the Linux-specific
		1052	sync_file_range call. If sync_file_range is not available or it returns
		1053	ENOSYS, then fdatasync or fsync is being substituted.
		1054
		1055	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1056	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1057	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1058	manpage for details.
		1059
		1060	=item aio_pathsync $path, $callback->($status)
		1061
		1062	This request tries to open, fsync and close the given path. This is a
		1063	composite request intended to sync directories after directory operations
		1064	(E.g. rename). This might not work on all operating systems or have any
		1065	specific effect, but usually it makes sure that directory changes get
		1066	written to disc. It works for anything that can be opened for read-only,
		1067	not just directories.
		1068
		1069	Future versions of this function might fall back to other methods when
		1070	C<fsync> on the directory fails (such as calling C<sync>).
		1071
		1072	Passes C<0> when everything went ok, and C<-1> on error.
		1073
		1074	=cut
		1075
		1076	sub aio_pathsync($;$) {
		1077	my ($path, $cb) = @_;
		1078
		1079	my $pri = aioreq_pri;
		1080	my $grp = aio_group $cb;
		1081
		1082	aioreq_pri $pri;
		1083	add $grp aio_open $path, O_RDONLY, 0, sub {
		1084	my ($fh) = @_;
		1085	if ($fh) {
		1086	aioreq_pri $pri;
		1087	add $grp aio_fsync $fh, sub {
		1088	$grp->result ($_[0]);
		1089
		1090	aioreq_pri $pri;
		1091	add $grp aio_close $fh;
		1092	};
		1093	} else {
		1094	$grp->result (-1);
		1095	}
		1096	};
		1097
		1098	$grp
		1099	}
		1100
		1101	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1102
		1103	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1104	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1105	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1106	scalar must only be modified in-place while an aio operation is pending on
		1107	it).
		1108
		1109	It calls the C<msync> function of your OS, if available, with the memory
		1110	area starting at C<$offset> in the string and ending C<$length> bytes
		1111	later. If C<$length> is negative, counts from the end, and if C<$length>
		1112	is C<undef>, then it goes till the end of the string. The flags can be
		1113	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1114	C<IO::AIO::MS_SYNC>.
		1115
		1116	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1117
		1118	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1119	scalars.
		1120
		1121	It touches (reads or writes) all memory pages in the specified
		1122	range inside the scalar. All caveats and parameters are the same
		1123	as for C<aio_msync>, above, except for flags, which must be either
		1124	C<0> (which reads all pages and ensures they are instantiated) or
		1125	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1126	writing an octet from it, which dirties the page).
		1127
		1128	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1129
		1130	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1131	scalars.
		1132
		1133	It reads in all the pages of the underlying storage into memory (if any)
		1134	and locks them, so they are not getting swapped/paged out or removed.
		1135
		1136	If C<$length> is undefined, then the scalar will be locked till the end.
		1137
		1138	On systems that do not implement C<mlock>, this function returns C<-1>
		1139	and sets errno to C<ENOSYS>.
		1140
		1141	Note that the corresponding C<munlock> is synchronous and is
		1142	documented under L<MISCELLANEOUS FUNCTIONS>.
		1143
		1144	Example: open a file, mmap and mlock it - both will be undone when
		1145	C<$data> gets destroyed.
		1146
		1147	open my $fh, "<", $path or die "$path: $!";
		1148	my $data;
		1149	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1150	aio_mlock $data; # mlock in background
		1151
		1152	=item aio_mlockall $flags, $callback->($status)
		1153
		1154	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1155	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1156
		1157	On systems that do not implement C<mlockall>, this function returns C<-1>
		1158	and sets errno to C<ENOSYS>.
		1159
		1160	Note that the corresponding C<munlockall> is synchronous and is
		1161	documented under L<MISCELLANEOUS FUNCTIONS>.
		1162
		1163	Example: asynchronously lock all current and future pages into memory.
		1164
		1165	aio_mlockall IO::AIO::MCL_FUTURE;
623		1166
624	=item aio_group $callback->(...)	1167	=item aio_group $callback->(...)
625		1168
626	This is a very special aio request: Instead of doing something, it is a	1169	This is a very special aio request: Instead of doing something, it is a
627	container for other aio requests, which is useful if you want to bundle	1170	container for other aio requests, which is useful if you want to bundle
…		…
677	=item cancel $req	1220	=item cancel $req
678		1221
679	Cancels the request, if possible. Has the effect of skipping execution	1222	Cancels the request, if possible. Has the effect of skipping execution
680	when entering the B<execute> state and skipping calling the callback when	1223	when entering the B<execute> state and skipping calling the callback when
681	entering the the B<result> state, but will leave the request otherwise	1224	entering the the B<result> state, but will leave the request otherwise
682	untouched. That means that requests that currently execute will not be	1225	untouched (with the exception of readdir). That means that requests that
683	stopped and resources held by the request will not be freed prematurely.	1226	currently execute will not be stopped and resources held by the request
		1227	will not be freed prematurely.
684		1228
685	=item cb $req $callback->(...)	1229	=item cb $req $callback->(...)
686		1230
687	Replace (or simply set) the callback registered to the request.	1231	Replace (or simply set) the callback registered to the request.
688		1232
…		…
739	Their lifetime, simplified, looks like this: when they are empty, they	1283	Their lifetime, simplified, looks like this: when they are empty, they
740	will finish very quickly. If they contain only requests that are in the	1284	will finish very quickly. If they contain only requests that are in the
741	C<done> state, they will also finish. Otherwise they will continue to	1285	C<done> state, they will also finish. Otherwise they will continue to
742	exist.	1286	exist.
743		1287
744	That means after creating a group you have some time to add requests. And	1288	That means after creating a group you have some time to add requests
745	in the callbacks of those requests, you can add further requests to the	1289	(precisely before the callback has been invoked, which is only done within
746	group. And only when all those requests have finished will the the group	1290	the C<poll_cb>). And in the callbacks of those requests, you can add
747	itself finish.	1291	further requests to the group. And only when all those requests have
		1292	finished will the the group itself finish.
748		1293
749	=over 4	1294	=over 4
750		1295
751	=item add $grp ...	1296	=item add $grp ...
752		1297
…		…
761	=item $grp->cancel_subs	1306	=item $grp->cancel_subs
762		1307
763	Cancel all subrequests and clears any feeder, but not the group request	1308	Cancel all subrequests and clears any feeder, but not the group request
764	itself. Useful when you queued a lot of events but got a result early.	1309	itself. Useful when you queued a lot of events but got a result early.
765		1310
		1311	The group request will finish normally (you cannot add requests to the
		1312	group).
		1313
766	=item $grp->result (...)	1314	=item $grp->result (...)
767		1315
768	Set the result value(s) that will be passed to the group callback when all	1316	Set the result value(s) that will be passed to the group callback when all
769	subrequests have finished and set thre groups errno to the current value	1317	subrequests have finished and set the groups errno to the current value
770	of errno (just like calling C<errno> without an error number). By default,	1318	of errno (just like calling C<errno> without an error number). By default,
771	no argument will be passed and errno is zero.	1319	no argument will be passed and errno is zero.
772		1320
773	=item $grp->errno ([$errno])	1321	=item $grp->errno ([$errno])
774		1322
…		…
785	=item feed $grp $callback->($grp)	1333	=item feed $grp $callback->($grp)
786		1334
787	Sets a feeder/generator on this group: every group can have an attached	1335	Sets a feeder/generator on this group: every group can have an attached
788	generator that generates requests if idle. The idea behind this is that,	1336	generator that generates requests if idle. The idea behind this is that,
789	although you could just queue as many requests as you want in a group,	1337	although you could just queue as many requests as you want in a group,
790	this might starve other requests for a potentially long time. For	1338	this might starve other requests for a potentially long time. For example,
791	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1339	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
792	requests, delaying any later requests for a long time.	1340	delaying any later requests for a long time.
793		1341
794	To avoid this, and allow incremental generation of requests, you can	1342	To avoid this, and allow incremental generation of requests, you can
795	instead a group and set a feeder on it that generates those requests. The	1343	instead a group and set a feeder on it that generates those requests. The
796	feed callback will be called whenever there are few enough (see C<limit>,	1344	feed callback will be called whenever there are few enough (see C<limit>,
797	below) requests active in the group itself and is expected to queue more	1345	below) requests active in the group itself and is expected to queue more
…		…
801	not impose any limits).	1349	not impose any limits).
802		1350
803	If the feed does not queue more requests when called, it will be	1351	If the feed does not queue more requests when called, it will be
804	automatically removed from the group.	1352	automatically removed from the group.
805		1353
806	If the feed limit is C<0>, it will be set to C<2> automatically.	1354	If the feed limit is C<0> when this method is called, it will be set to
		1355	C<2> automatically.
807		1356
808	Example:	1357	Example:
809		1358
810	# stat all files in @files, but only ever use four aio requests concurrently:	1359	# stat all files in @files, but only ever use four aio requests concurrently:
811		1360
…		…
823	Sets the feeder limit for the group: The feeder will be called whenever	1372	Sets the feeder limit for the group: The feeder will be called whenever
824	the group contains less than this many requests.	1373	the group contains less than this many requests.
825		1374
826	Setting the limit to C<0> will pause the feeding process.	1375	Setting the limit to C<0> will pause the feeding process.
827		1376
		1377	The default value for the limit is C<0>, but note that setting a feeder
		1378	automatically bumps it up to C<2>.
		1379
828	=back	1380	=back
829		1381
830	=head2 SUPPORT FUNCTIONS	1382	=head2 SUPPORT FUNCTIONS
831		1383
		1384	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1385
832	=over 4	1386	=over 4
833		1387
834	=item $fileno = IO::AIO::poll_fileno	1388	=item $fileno = IO::AIO::poll_fileno
835		1389
836	Return the I<request result pipe file descriptor>. This filehandle must be	1390	Return the I<request result pipe file descriptor>. This filehandle must be
837	polled for reading by some mechanism outside this module (e.g. Event or	1391	polled for reading by some mechanism outside this module (e.g. EV, Glib,
838	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1392	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
839	to call C<poll_cb> to check the results.	1393	you have to call C<poll_cb> to check the results.
840		1394
841	See C<poll_cb> for an example.	1395	See C<poll_cb> for an example.
842		1396
843	=item IO::AIO::poll_cb	1397	=item IO::AIO::poll_cb
844		1398
845	Process all outstanding events on the result pipe. You have to call this	1399	Process some outstanding events on the result pipe. You have to call this
846	regularly. Returns the number of events processed. Returns immediately	1400	regularly. Returns C<0> if all events could be processed, or C<-1> if it
847	when no events are outstanding.	1401	returned earlier for whatever reason. Returns immediately when no events
		1402	are outstanding. The amount of events processed depends on the settings of
		1403	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
848		1404
849	If not all requests were processed for whatever reason, the filehandle	1405	If not all requests were processed for whatever reason, the filehandle
850	will still be ready when C<poll_cb> returns.	1406	will still be ready when C<poll_cb> returns, so normally you don't have to
		1407	do anything special to have it called later.
851		1408
852	Example: Install an Event watcher that automatically calls	1409	Example: Install an Event watcher that automatically calls
853	IO::AIO::poll_cb with high priority:	1410	IO::AIO::poll_cb with high priority (more examples can be found in the
		1411	SYNOPSIS section, at the top of this document):
854		1412
855	Event->io (fd => IO::AIO::poll_fileno,	1413	Event->io (fd => IO::AIO::poll_fileno,
856	poll => 'r', async => 1,	1414	poll => 'r', async => 1,
857	cb => \&IO::AIO::poll_cb);	1415	cb => \&IO::AIO::poll_cb);
858		1416
859	=item IO::AIO::poll_some $max_requests	1417	=item IO::AIO::poll_wait
860		1418
861	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests	1419	If there are any outstanding requests and none of them in the result
862	at a time.	1420	phase, wait till the result filehandle becomes ready for reading (simply
		1421	does a C<select> on the filehandle. This is useful if you want to
		1422	synchronously wait for some requests to finish).
863		1423
864	Useful if you want to ensure some level of interactiveness when perl is	1424	See C<nreqs> for an example.
865	not fast enough to process all requests in time.	1425
		1426	=item IO::AIO::poll
		1427
		1428	Waits until some requests have been handled.
		1429
		1430	Returns the number of requests processed, but is otherwise strictly
		1431	equivalent to:
		1432
		1433	IO::AIO::poll_wait, IO::AIO::poll_cb
		1434
		1435	=item IO::AIO::flush
		1436
		1437	Wait till all outstanding AIO requests have been handled.
		1438
		1439	Strictly equivalent to:
		1440
		1441	IO::AIO::poll_wait, IO::AIO::poll_cb
		1442	while IO::AIO::nreqs;
		1443
		1444	=item IO::AIO::max_poll_reqs $nreqs
		1445
		1446	=item IO::AIO::max_poll_time $seconds
		1447
		1448	These set the maximum number of requests (default C<0>, meaning infinity)
		1449	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1450	the maximum amount of time (default C<0>, meaning infinity) spent in
		1451	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1452	of time C<poll_cb> is allowed to use).
		1453
		1454	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1455	syscall per request processed, which is not normally a problem unless your
		1456	callbacks are really really fast or your OS is really really slow (I am
		1457	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1458
		1459	Setting these is useful if you want to ensure some level of
		1460	interactiveness when perl is not fast enough to process all requests in
		1461	time.
		1462
		1463	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
866		1464
867	Example: Install an Event watcher that automatically calls	1465	Example: Install an Event watcher that automatically calls
868	IO::AIO::poll_some with low priority, to ensure that other parts of the	1466	IO::AIO::poll_cb with low priority, to ensure that other parts of the
869	program get the CPU sometimes even under high AIO load.	1467	program get the CPU sometimes even under high AIO load.
870		1468
		1469	# try not to spend much more than 0.1s in poll_cb
		1470	IO::AIO::max_poll_time 0.1;
		1471
		1472	# use a low priority so other tasks have priority
871	Event->io (fd => IO::AIO::poll_fileno,	1473	Event->io (fd => IO::AIO::poll_fileno,
872	poll => 'r', nice => 1,	1474	poll => 'r', nice => 1,
873	cb => sub { IO::AIO::poll_some 256 });	1475	cb => &IO::AIO::poll_cb);
874		1476
875	=item IO::AIO::poll_wait	1477	=back
876		1478
877	Wait till the result filehandle becomes ready for reading (simply does a	1479	=head3 CONTROLLING THE NUMBER OF THREADS
878	C<select> on the filehandle. This is useful if you want to synchronously wait
879	for some requests to finish).
880		1480
881	See C<nreqs> for an example.	1481	=over
882
883	=item IO::AIO::nreqs
884
885	Returns the number of requests currently in the ready, execute or pending
886	states (i.e. for which their callback has not been invoked yet).
887
888	Example: wait till there are no outstanding requests anymore:
889
890	IO::AIO::poll_wait, IO::AIO::poll_cb
891	while IO::AIO::nreqs;
892
893	=item IO::AIO::nready
894
895	Returns the number of requests currently in the ready state (not yet
896	executed).
897
898	=item IO::AIO::npending
899
900	Returns the number of requests currently in the pending state (executed,
901	but not yet processed by poll_cb).
902
903	=item IO::AIO::flush
904
905	Wait till all outstanding AIO requests have been handled.
906
907	Strictly equivalent to:
908
909	IO::AIO::poll_wait, IO::AIO::poll_cb
910	while IO::AIO::nreqs;
911
912	=item IO::AIO::poll
913
914	Waits until some requests have been handled.
915
916	Strictly equivalent to:
917
918	IO::AIO::poll_wait, IO::AIO::poll_cb
919	if IO::AIO::nreqs;
920		1482
921	=item IO::AIO::min_parallel $nthreads	1483	=item IO::AIO::min_parallel $nthreads
922		1484
923	Set the minimum number of AIO threads to C<$nthreads>. The current	1485	Set the minimum number of AIO threads to C<$nthreads>. The current
924	default is C<8>, which means eight asynchronous operations can execute	1486	default is C<8>, which means eight asynchronous operations can execute
925	concurrently at any one time (the number of outstanding requests,	1487	concurrently at any one time (the number of outstanding requests,
926	however, is unlimited).	1488	however, is unlimited).
927		1489
928	IO::AIO starts threads only on demand, when an AIO request is queued and	1490	IO::AIO starts threads only on demand, when an AIO request is queued and
929	no free thread exists.	1491	no free thread exists. Please note that queueing up a hundred requests can
		1492	create demand for a hundred threads, even if it turns out that everything
		1493	is in the cache and could have been processed faster by a single thread.
930		1494
931	It is recommended to keep the number of threads relatively low, as some	1495	It is recommended to keep the number of threads relatively low, as some
932	Linux kernel versions will scale negatively with the number of threads	1496	Linux kernel versions will scale negatively with the number of threads
933	(higher parallelity => MUCH higher latency). With current Linux 2.6	1497	(higher parallelity => MUCH higher latency). With current Linux 2.6
934	versions, 4-32 threads should be fine.	1498	versions, 4-32 threads should be fine.
…		…
948	This module automatically runs C<max_parallel 0> at program end, to ensure	1512	This module automatically runs C<max_parallel 0> at program end, to ensure
949	that all threads are killed and that there are no outstanding requests.	1513	that all threads are killed and that there are no outstanding requests.
950		1514
951	Under normal circumstances you don't need to call this function.	1515	Under normal circumstances you don't need to call this function.
952		1516
		1517	=item IO::AIO::max_idle $nthreads
		1518
		1519	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1520	threads that did not get a request to process within 10 seconds). That
		1521	means if a thread becomes idle while C<$nthreads> other threads are also
		1522	idle, it will free its resources and exit.
		1523
		1524	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1525	to allow for extremely high load situations, but want to free resources
		1526	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1527
		1528	The default is probably ok in most situations, especially if thread
		1529	creation is fast. If thread creation is very slow on your system you might
		1530	want to use larger values.
		1531
953	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1532	=item IO::AIO::max_outstanding $maxreqs
954		1533
955	This is a very bad function to use in interactive programs because it	1534	This is a very bad function to use in interactive programs because it
956	blocks, and a bad way to reduce concurrency because it is inexact: Better	1535	blocks, and a bad way to reduce concurrency because it is inexact: Better
957	use an C<aio_group> together with a feed callback.	1536	use an C<aio_group> together with a feed callback.
958		1537
959	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1538	Sets the maximum number of outstanding requests to C<$nreqs>. If you
960	to queue up more than this number of requests, the next call to the	1539	do queue up more than this number of requests, the next call to the
961	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)	1540	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
962	function will block until the limit is no longer exceeded.	1541	function will block until the limit is no longer exceeded.
963		1542
964	The default value is very large, so there is no practical limit on the	1543	The default value is very large, so there is no practical limit on the
965	number of outstanding requests.	1544	number of outstanding requests.
966		1545
967	You can still queue as many requests as you want. Therefore,	1546	You can still queue as many requests as you want. Therefore,
968	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	1547	C<max_outstanding> is mainly useful in simple scripts (with low values) or
969	as a stop gap to shield against fatal memory overflow (with large values).	1548	as a stop gap to shield against fatal memory overflow (with large values).
970		1549
971	=back	1550	=back
972		1551
		1552	=head3 STATISTICAL INFORMATION
		1553
		1554	=over
		1555
		1556	=item IO::AIO::nreqs
		1557
		1558	Returns the number of requests currently in the ready, execute or pending
		1559	states (i.e. for which their callback has not been invoked yet).
		1560
		1561	Example: wait till there are no outstanding requests anymore:
		1562
		1563	IO::AIO::poll_wait, IO::AIO::poll_cb
		1564	while IO::AIO::nreqs;
		1565
		1566	=item IO::AIO::nready
		1567
		1568	Returns the number of requests currently in the ready state (not yet
		1569	executed).
		1570
		1571	=item IO::AIO::npending
		1572
		1573	Returns the number of requests currently in the pending state (executed,
		1574	but not yet processed by poll_cb).
		1575
		1576	=back
		1577
		1578	=head3 MISCELLANEOUS FUNCTIONS
		1579
		1580	IO::AIO implements some functions that might be useful, but are not
		1581	asynchronous.
		1582
		1583	=over 4
		1584
		1585	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1586
		1587	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1588	but is blocking (this makes most sense if you know the input data is
		1589	likely cached already and the output filehandle is set to non-blocking
		1590	operations).
		1591
		1592	Returns the number of bytes copied, or C<-1> on error.
		1593
		1594	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1595
		1596	Simply calls the C<posix_fadvise> function (see its
		1597	manpage for details). The following advice constants are
		1598	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1599	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1600	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1601
		1602	On systems that do not implement C<posix_fadvise>, this function returns
		1603	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1604
		1605	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1606
		1607	Simply calls the C<posix_madvise> function (see its
		1608	manpage for details). The following advice constants are
		1609	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1610	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1611
		1612	On systems that do not implement C<posix_madvise>, this function returns
		1613	ENOSYS, otherwise the return value of C<posix_madvise>.
		1614
		1615	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1616
		1617	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1618	$scalar (see its manpage for details). The following protect
		1619	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1620	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1621
		1622	On systems that do not implement C<mprotect>, this function returns
		1623	ENOSYS, otherwise the return value of C<mprotect>.
		1624
		1625	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1626
		1627	Memory-maps a file (or anonymous memory range) and attaches it to the
		1628	given C<$scalar>, which will act like a string scalar.
		1629
		1630	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1631	change the string length, and most read-only operations such as copying it
		1632	or searching it with regexes and so on.
		1633
		1634	Anything else is unsafe and will, at best, result in memory leaks.
		1635
		1636	The memory map associated with the C<$scalar> is automatically removed
		1637	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1638	C<IO::AIO::munmap> functions are called.
		1639
		1640	This calls the C<mmap>(2) function internally. See your system's manual
		1641	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1642
		1643	The C<$length> must be larger than zero and smaller than the actual
		1644	filesize.
		1645
		1646	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1647	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1648
		1649	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1650	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1651	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1652	(which is set to C<MAP_ANON> if your system only provides this
		1653	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1654	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1655	C<IO::AIO::MAP_NONBLOCK>
		1656
		1657	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1658
		1659	C<$offset> is the offset from the start of the file - it generally must be
		1660	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1661
		1662	Example:
		1663
		1664	use Digest::MD5;
		1665	use IO::AIO;
		1666
		1667	open my $fh, "<verybigfile"
		1668	or die "$!";
		1669
		1670	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1671	or die "verybigfile: $!";
		1672
		1673	my $fast_md5 = md5 $data;
		1674
		1675	=item IO::AIO::munmap $scalar
		1676
		1677	Removes a previous mmap and undefines the C<$scalar>.
		1678
		1679	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1680
		1681	Calls the C<munlock> function, undoing the effects of a previous
		1682	C<aio_mlock> call (see its description for details).
		1683
		1684	=item IO::AIO::munlockall
		1685
		1686	Calls the C<munlockall> function.
		1687
		1688	On systems that do not implement C<munlockall>, this function returns
		1689	ENOSYS, otherwise the return value of C<munlockall>.
		1690
		1691	=back
		1692
973	=cut	1693	=cut
974		1694
975	# support function to convert a fd into a perl filehandle
976	sub _fd2fh {
977	return undef if $_[0] < 0;
978
979	# try to generate nice filehandles
980	my $sym = "IO::AIO::fd#$_[0]";
981	local *$sym;
982
983	open *$sym, "+<&=$_[0]" # usually works under any unix
984	or open *$sym, "<&=$_[0]" # cygwin needs this
985	or open *$sym, ">&=$_[0]" # or this
986	or return undef;
987
988	*$sym
989	}
990
991	min_parallel 8;	1695	min_parallel 8;
992		1696
993	END {	1697	END { flush }
994	flush;
995	};
996		1698
997	1;	1699	1;
		1700
		1701	=head1 EVENT LOOP INTEGRATION
		1702
		1703	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1704	automatically into many event loops:
		1705
		1706	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1707	use AnyEvent::AIO;
		1708
		1709	You can also integrate IO::AIO manually into many event loops, here are
		1710	some examples of how to do this:
		1711
		1712	# EV integration
		1713	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1714
		1715	# Event integration
		1716	Event->io (fd => IO::AIO::poll_fileno,
		1717	poll => 'r',
		1718	cb => \&IO::AIO::poll_cb);
		1719
		1720	# Glib/Gtk2 integration
		1721	add_watch Glib::IO IO::AIO::poll_fileno,
		1722	in => sub { IO::AIO::poll_cb; 1 };
		1723
		1724	# Tk integration
		1725	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1726	readable => \&IO::AIO::poll_cb);
		1727
		1728	# Danga::Socket integration
		1729	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1730	\&IO::AIO::poll_cb);
998		1731
999	=head2 FORK BEHAVIOUR	1732	=head2 FORK BEHAVIOUR
1000		1733
1001	This module should do "the right thing" when the process using it forks:	1734	This module should do "the right thing" when the process using it forks:
1002		1735
…		…
1020	bytes of memory. In addition, stat requests need a stat buffer (possibly	1753	bytes of memory. In addition, stat requests need a stat buffer (possibly
1021	a few hundred bytes), readdir requires a result buffer and so on. Perl	1754	a few hundred bytes), readdir requires a result buffer and so on. Perl
1022	scalars and other data passed into aio requests will also be locked and	1755	scalars and other data passed into aio requests will also be locked and
1023	will consume memory till the request has entered the done state.	1756	will consume memory till the request has entered the done state.
1024		1757
1025	This is now awfully much, so queuing lots of requests is not usually a	1758	This is not awfully much, so queuing lots of requests is not usually a
1026	problem.	1759	problem.
1027		1760
1028	Per-thread usage:	1761	Per-thread usage:
1029		1762
1030	In the execution phase, some aio requests require more memory for	1763	In the execution phase, some aio requests require more memory for
…		…
1035		1768
1036	Known bugs will be fixed in the next release.	1769	Known bugs will be fixed in the next release.
1037		1770
1038	=head1 SEE ALSO	1771	=head1 SEE ALSO
1039		1772
1040	L<Coro::AIO>.	1773	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1774	more natural syntax.
1041		1775
1042	=head1 AUTHOR	1776	=head1 AUTHOR
1043		1777
1044	Marc Lehmann <schmorp@schmorp.de>	1778	Marc Lehmann <schmorp@schmorp.de>
1045	http://home.schmorp.de/	1779	http://home.schmorp.de/

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