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Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs.
Revision 1.187 by root, Fri Feb 11 00:05:17 2011 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
…		…
18	};	19	};
19		20
20	# version 2+ has request and group objects	21	# version 2+ has request and group objects
21	use IO::AIO 2;	22	use IO::AIO 2;
22		23
		24	aioreq_pri 4; # give next request a very high priority
23	my $req = aio_unlink "/tmp/file", sub { };	25	my $req = aio_unlink "/tmp/file", sub { };
24	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
25		27
26	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
28		30
29	# AnyEvent integration
30	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
31	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
32
33	# Event integration
34	Event->io (fd => IO::AIO::poll_fileno,
35	poll => 'r',
36	cb => \&IO::AIO::poll_cb);
37
38	# Glib/Gtk2 integration
39	add_watch Glib::IO IO::AIO::poll_fileno,
40	in => sub { IO::AIO::poll_cb; 1 };
41
42	# Tk integration
43	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
44	readable => \&IO::AIO::poll_cb);
45
46	# Danga::Socket integration
47	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
48	\&IO::AIO::poll_cb);
49
50	=head1 DESCRIPTION	31	=head1 DESCRIPTION
51		32
52	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
53	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>).
54		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.
		52
55	Currently, a number of threads are started that execute your read/writes	53	In this version, a number of threads are started that execute your
56	and signal their completion. You don't need thread support in your libc or	54	requests and signal their completion. You don't need thread support
57	perl, and the threads created by this module will not be visible to the	55	in perl, and the threads created by this module will not be visible
58	pthreads library. In the future, this module might make use of the native	56	to perl. In the future, this module might make use of the native aio
59	aio functions available on many operating systems. However, they are often	57	functions available on many operating systems. However, they are often
60	not well-supported (Linux doesn't allow them on normal files currently,	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
61	for example), and they would only support aio_read and aio_write, so the	59	files currently, for example), and they would only support aio_read and
62	remaining functionality would have to be implemented using threads anyway.	60	aio_write, so the remaining functionality would have to be implemented
		61	using threads anyway.
63		62
64	Although the module will work with in the presence of other threads, it is	63	Although the module will work in the presence of other (Perl-) threads,
65	currently not reentrant, so use appropriate locking yourself, always call	64	it is currently not reentrant in any way, so use appropriate locking
66	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	65	yourself, always call C<poll_cb> from within the same thread, or never
67	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;
		109
		110	=head1 REQUEST ANATOMY AND LIFETIME
		111
		112	Every C<aio_*> function creates a request. which is a C data structure not
		113	directly visible to Perl.
		114
		115	If called in non-void context, every request function returns a Perl
		116	object representing the request. In void context, nothing is returned,
		117	which saves a bit of memory.
		118
		119	The perl object is a fairly standard ref-to-hash object. The hash contents
		120	are not used by IO::AIO so you are free to store anything you like in it.
		121
		122	During their existance, aio requests travel through the following states,
		123	in order:
		124
		125	=over 4
		126
		127	=item ready
		128
		129	Immediately after a request is created it is put into the ready state,
		130	waiting for a thread to execute it.
		131
		132	=item execute
		133
		134	A thread has accepted the request for processing and is currently
		135	executing it (e.g. blocking in read).
		136
		137	=item pending
		138
		139	The request has been executed and is waiting for result processing.
		140
		141	While request submission and execution is fully asynchronous, result
		142	processing is not and relies on the perl interpreter calling C<poll_cb>
		143	(or another function with the same effect).
		144
		145	=item result
		146
		147	The request results are processed synchronously by C<poll_cb>.
		148
		149	The C<poll_cb> function will process all outstanding aio requests by
		150	calling their callbacks, freeing memory associated with them and managing
		151	any groups they are contained in.
		152
		153	=item done
		154
		155	Request has reached the end of its lifetime and holds no resources anymore
		156	(except possibly for the Perl object, but its connection to the actual
		157	aio request is severed and calling its methods will either do nothing or
		158	result in a runtime error).
		159
		160	=back
68		161
69	=cut	162	=cut
70		163
71	package IO::AIO;	164	package IO::AIO;
72		165
73	no warnings;	166	use Carp ();
74	use strict 'vars';	167
		168	use common::sense;
75		169
76	use base 'Exporter';	170	use base 'Exporter';
77		171
78	BEGIN {	172	BEGIN {
79	our $VERSION = '2.0';	173	our $VERSION = '3.72';
80		174
81	our @EXPORT = 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
82	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
83	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	177	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
		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
84	aio_group);	183	aio_statvfs);
85	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	184
		185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		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
86		194
87	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	195	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
88		196
89	require XSLoader;	197	require XSLoader;
90	XSLoader::load ("IO::AIO", $VERSION);	198	XSLoader::load ("IO::AIO", $VERSION);
91	}	199	}
92		200
93	=head1 FUNCTIONS	201	=head1 FUNCTIONS
94		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, $length = undef
		273	IO::AIO::munlockall
		274
95	=head2 AIO FUNCTIONS	275	=head2 AIO REQUEST FUNCTIONS
96		276
97	All the C<aio_*> calls are more or less thin wrappers around the syscall	277	All the C<aio_*> calls are more or less thin wrappers around the syscall
98	with the same name (sans C<aio_>). The arguments are similar or identical,	278	with the same name (sans C<aio_>). The arguments are similar or identical,
99	and they all accept an additional (and optional) C<$callback> argument	279	and they all accept an additional (and optional) C<$callback> argument
100	which must be a code reference. This code reference will get called with	280	which must be a code reference. This code reference will get called with
101	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	281	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
102	perl, which usually delivers "false") as it's sole argument when the given	282	perl, which usually delivers "false") as its sole argument after the given
103	syscall has been executed asynchronously.	283	syscall has been executed asynchronously.
104		284
105	All functions expecting a filehandle keep a copy of the filehandle	285	All functions expecting a filehandle keep a copy of the filehandle
106	internally until the request has finished.	286	internally until the request has finished.
107		287
108	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
109	manipulation of those requests while they are in-flight.	289	further manipulation of those requests while they are in-flight.
110		290
111	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
112	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
113	request is being executed, the current working directory could have	293	request is being executed, the current working directory could have
114	changed. Alternatively, you can make sure that you never change the	294	changed. Alternatively, you can make sure that you never change the
115	current working directory.	295	current working directory anywhere in the program and then use relative
		296	paths.
116		297
117	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
118	always pass in filenames you got from outside (command line, readdir	299	in filenames you got from outside (command line, readdir etc.) without
119	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	300	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
120	your pathnames to the locale (or other) encoding in effect in the user	301	your pathnames to the locale (or other) encoding in effect in the user
121	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	302	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
122	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.
123		307
124	=over 4	308	=over 4
		309
		310	=item $prev_pri = aioreq_pri [$pri]
		311
		312	Returns the priority value that would be used for the next request and, if
		313	C<$pri> is given, sets the priority for the next aio request.
		314
		315	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		316	and C<4>, respectively. Requests with higher priority will be serviced
		317	first.
		318
		319	The priority will be reset to C<0> after each call to one of the C<aio_*>
		320	functions.
		321
		322	Example: open a file with low priority, then read something from it with
		323	higher priority so the read request is serviced before other low priority
		324	open requests (potentially spamming the cache):
		325
		326	aioreq_pri -3;
		327	aio_open ..., sub {
		328	return unless $_[0];
		329
		330	aioreq_pri -2;
		331	aio_read $_[0], ..., sub {
		332	...
		333	};
		334	};
		335
		336
		337	=item aioreq_nice $pri_adjust
		338
		339	Similar to C<aioreq_pri>, but subtracts the given value from the current
		340	priority, so the effect is cumulative.
		341
125		342
126	=item aio_open $pathname, $flags, $mode, $callback->($fh)	343	=item aio_open $pathname, $flags, $mode, $callback->($fh)
127		344
128	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
129	created filehandle for the file.	346	created filehandle for the file.
…		…
135	list. They are the same as used by C<sysopen>.	352	list. They are the same as used by C<sysopen>.
136		353
137	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
138	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>,
139	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,
140	and C<0666> or C<0777> if you do).	357	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		358	by the umask in effect then the request is being executed, so better never
		359	change the umask.
141		360
142	Example:	361	Example:
143		362
144	aio_open "/etc/passwd", O_RDONLY, 0, sub {	363	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
145	if ($_[0]) {	364	if ($_[0]) {
146	print "open successful, fh is $_[0]\n";	365	print "open successful, fh is $_[0]\n";
147	...	366	...
148	} else {	367	} else {
149	die "open failed: $!\n";	368	die "open failed: $!\n";
150	}	369	}
151	};	370	};
152		371
		372
153	=item aio_close $fh, $callback->($status)	373	=item aio_close $fh, $callback->($status)
154		374
155	Asynchronously close a file and call the callback with the result	375	Asynchronously close a file and call the callback with the result
156	code. I<WARNING:> although accepted, you should not pass in a perl	376	code.
157	filehandle here, as perl will likely close the file descriptor another
158	time when the filehandle is destroyed. Normally, you can safely call perls
159	C<close> or just let filehandles go out of scope.
160		377
161	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
162	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
163		389
164	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	390	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
165		391
166	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	392	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
167		393
168	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
169	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<$dataoffset>
170	callback without the actual number of bytes read (or -1 on error, just	396	and calls the callback without the actual number of bytes read (or -1 on
171	like the syscall).	397	error, just like the syscall).
		398
		399	C<aio_read> will, like C<sysread>, shrink or grow the C<$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<$data>.
172		411
173	The C<$data> scalar I<MUST NOT> be modified in any way while the request	412	The C<$data> scalar I<MUST NOT> be modified in any way while the request
174	is outstanding. Modifying it can result in segfaults or WW3 (if the	413	is outstanding. Modifying it can result in segfaults or World War III (if
175	necessary/optional hardware is installed).	414	the necessary/optional hardware is installed).
176		415
177	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	416	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
178	offset C<0> within the scalar:	417	offset C<0> within the scalar:
179		418
180	aio_read $fh, 7, 15, $buffer, 0, sub {	419	aio_read $fh, 7, 15, $buffer, 0, sub {
181	$_[0] > 0 or die "read error: $!";	420	$_[0] > 0 or die "read error: $!";
182	print "read $_[0] bytes: <$buffer>\n";	421	print "read $_[0] bytes: <$buffer>\n";
183	};	422	};
184		423
185	=item aio_move $srcpath, $dstpath, $callback->($status)
186
187	Try to move the I<file> (directories not supported as either source or
188	destination) from C<$srcpath> to C<$dstpath> and call the callback with
189	the C<0> (error) or C<-1> ok.
190
191	This is a composite request that tries to rename(2) the file first. If
192	rename files with C<EXDEV>, it creates the destination file with mode 0200
193	and copies the contents of the source file into it using C<aio_sendfile>,
194	followed by restoring atime, mtime, access mode and uid/gid, in that
195	order, and unlinking the C<$srcpath>.
196
197	If an error occurs, the partial destination file will be unlinked, if
198	possible, except when setting atime, mtime, access mode and uid/gid, where
199	errors are being ignored.
200
201	=cut
202
203	sub aio_move($$$) {
204	my ($src, $dst, $cb) = @_;
205
206	my $grp = aio_group;
207
208	add $grp aio_rename $src, $dst, sub {
209	if ($_[0] && $! == EXDEV) {
210	add $grp aio_open $src, O_RDONLY, 0, sub {
211	if (my $src_fh = $_[0]) {
212	my @stat = stat $src_fh;
213
214	add $grp aio_open $dst, O_WRONLY, 0200, sub {
215	if (my $dst_fh = $_[0]) {
216	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
217	close $src_fh;
218
219	if ($_[0] == $stat[7]) {
220	utime $stat[8], $stat[9], $dst;
221	chmod $stat[2] & 07777, $dst_fh;
222	chown $stat[4], $stat[5], $dst_fh;
223	close $dst_fh;
224
225	add $grp aio_unlink $src, sub {
226	$cb->($_[0]);
227	};
228	} else {
229	my $errno = $!;
230	add $grp aio_unlink $dst, sub {
231	$! = $errno;
232	$cb->(-1);
233	};
234	}
235	};
236	} else {
237	$cb->(-1);
238	}
239	},
240
241	} else {
242	$cb->(-1);
243	}
244	};
245	} else {
246	$cb->($_[0]);
247	}
248	};
249
250	$grp
251	}
252		424
253	=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)
254		426
255	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
256	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
257	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
258	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
259	other.	431	other.
260		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
261	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
262	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
263	socket, and C<$in_fh> should refer to mmap'able file.	451	socket, and C<$in_fh> should refer to an mmap'able file.
264		452
265	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>,
266	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
267	regardless of the limitations of the operating system.	456	filehandle regardless of the limitations of the operating system.
268		457
269	Please note, however, that C<aio_sendfile> can read more bytes from
270	C<$in_fh> than are written, and there is no way to find out how many
271	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
272	provides the number of bytes written to C<$out_fh>. Only if the result
273	value equals C<$length> one can assume that C<$length> bytes have been
274	read.
275		458
276	=item aio_readahead $fh,$offset,$length, $callback->($retval)	459	=item aio_readahead $fh,$offset,$length, $callback->($retval)
277		460
278	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
279	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>
…		…
285	file. The current file offset of the file is left unchanged.	468	file. The current file offset of the file is left unchanged.
286		469
287	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
288	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.
289		472
		473
290	=item aio_stat $fh_or_path, $callback->($status)	474	=item aio_stat $fh_or_path, $callback->($status)
291		475
292	=item aio_lstat $fh, $callback->($status)	476	=item aio_lstat $fh, $callback->($status)
293		477
294	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
…		…
299	for an explanation.	483	for an explanation.
300		484
301	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	485	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
302	error when stat'ing a large file, the results will be silently truncated	486	error when stat'ing a large file, the results will be silently truncated
303	unless perl itself is compiled with large file support.	487	unless perl itself is compiled with large file support.
		488
		489	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		490	following constants and functions (if not implemented, the constants will
		491	be C<0> and the functions will either C<croak> or fall back on traditional
		492	behaviour).
		493
		494	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		495	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		496	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
304		497
305	Example: Print the length of F</etc/passwd>:	498	Example: Print the length of F</etc/passwd>:
306		499
307	aio_stat "/etc/passwd", sub {	500	aio_stat "/etc/passwd", sub {
308	$_[0] and die "stat failed: $!";	501	$_[0] and die "stat failed: $!";
309	print "size is ", -s _, "\n";	502	print "size is ", -s _, "\n";
310	};	503	};
311		504
		505
		506	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		507
		508	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		509	whether a file handle or path was passed.
		510
		511	On success, the callback is passed a hash reference with the following
		512	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		513	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		514	is passed.
		515
		516	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		517	C<ST_NOSUID>.
		518
		519	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		520	their correct value when available, or to C<0> on systems that do
		521	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		522	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		523	C<ST_NODIRATIME> and C<ST_RELATIME>.
		524
		525	Example: stat C</wd> and dump out the data if successful.
		526
		527	aio_statvfs "/wd", sub {
		528	my $f = $_[0]
		529	or die "statvfs: $!";
		530
		531	use Data::Dumper;
		532	say Dumper $f;
		533	};
		534
		535	# result:
		536	{
		537	bsize => 1024,
		538	bfree => 4333064312,
		539	blocks => 10253828096,
		540	files => 2050765568,
		541	flag => 4096,
		542	favail => 2042092649,
		543	bavail => 4333064312,
		544	ffree => 2042092649,
		545	namemax => 255,
		546	frsize => 1024,
		547	fsid => 1810
		548	}
		549
		550
		551	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		552
		553	Works like perl's C<utime> function (including the special case of $atime
		554	and $mtime being undef). Fractional times are supported if the underlying
		555	syscalls support them.
		556
		557	When called with a pathname, uses utimes(2) if available, otherwise
		558	utime(2). If called on a file descriptor, uses futimes(2) if available,
		559	otherwise returns ENOSYS, so this is not portable.
		560
		561	Examples:
		562
		563	# set atime and mtime to current time (basically touch(1)):
		564	aio_utime "path", undef, undef;
		565	# set atime to current time and mtime to beginning of the epoch:
		566	aio_utime "path", time, undef; # undef==0
		567
		568
		569	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		570
		571	Works like perl's C<chown> function, except that C<undef> for either $uid
		572	or $gid is being interpreted as "do not change" (but -1 can also be used).
		573
		574	Examples:
		575
		576	# same as "chown root path" in the shell:
		577	aio_chown "path", 0, -1;
		578	# same as above:
		579	aio_chown "path", 0, undef;
		580
		581
		582	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		583
		584	Works like truncate(2) or ftruncate(2).
		585
		586
		587	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		588
		589	Works like perl's C<chmod> function.
		590
		591
312	=item aio_unlink $pathname, $callback->($status)	592	=item aio_unlink $pathname, $callback->($status)
313		593
314	Asynchronously unlink (delete) a file and call the callback with the	594	Asynchronously unlink (delete) a file and call the callback with the
315	result code.	595	result code.
316		596
		597
		598	=item aio_mknod $path, $mode, $dev, $callback->($status)
		599
		600	[EXPERIMENTAL]
		601
		602	Asynchronously create a device node (or fifo). See mknod(2).
		603
		604	The only (POSIX-) portable way of calling this function is:
		605
		606	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		607
		608	See C<aio_stat> for info about some potentially helpful extra constants
		609	and functions.
		610
317	=item aio_link $srcpath, $dstpath, $callback->($status)	611	=item aio_link $srcpath, $dstpath, $callback->($status)
318		612
319	Asynchronously create a new link to the existing object at C<$srcpath> at	613	Asynchronously create a new link to the existing object at C<$srcpath> at
320	the path C<$dstpath> and call the callback with the result code.	614	the path C<$dstpath> and call the callback with the result code.
321		615
		616
322	=item aio_symlink $srcpath, $dstpath, $callback->($status)	617	=item aio_symlink $srcpath, $dstpath, $callback->($status)
323		618
324	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	619	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
325	the path C<$dstpath> and call the callback with the result code.	620	the path C<$dstpath> and call the callback with the result code.
326		621
		622
		623	=item aio_readlink $path, $callback->($link)
		624
		625	Asynchronously read the symlink specified by C<$path> and pass it to
		626	the callback. If an error occurs, nothing or undef gets passed to the
		627	callback.
		628
		629
327	=item aio_rename $srcpath, $dstpath, $callback->($status)	630	=item aio_rename $srcpath, $dstpath, $callback->($status)
328		631
329	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	632	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
330	rename(2) and call the callback with the result code.	633	rename(2) and call the callback with the result code.
331		634
		635
		636	=item aio_mkdir $pathname, $mode, $callback->($status)
		637
		638	Asynchronously mkdir (create) a directory and call the callback with
		639	the result code. C<$mode> will be modified by the umask at the time the
		640	request is executed, so do not change your umask.
		641
		642
332	=item aio_rmdir $pathname, $callback->($status)	643	=item aio_rmdir $pathname, $callback->($status)
333		644
334	Asynchronously rmdir (delete) a directory and call the callback with the	645	Asynchronously rmdir (delete) a directory and call the callback with the
335	result code.	646	result code.
		647
336		648
337	=item aio_readdir $pathname, $callback->($entries)	649	=item aio_readdir $pathname, $callback->($entries)
338		650
339	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	651	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
340	directory (i.e. opendir + readdir + closedir). The entries will not be	652	directory (i.e. opendir + readdir + closedir). The entries will not be
341	sorted, and will B<NOT> include the C<.> and C<..> entries.	653	sorted, and will B<NOT> include the C<.> and C<..> entries.
342		654
343	The callback a single argument which is either C<undef> or an array-ref	655	The callback is passed a single argument which is either C<undef> or an
344	with the filenames.	656	array-ref with the filenames.
		657
		658
		659	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		660
		661	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		662	behaviour and output format. In case of an error, C<$entries> will be
		663	C<undef>.
		664
		665	The flags are a combination of the following constants, ORed together (the
		666	flags will also be passed to the callback, possibly modified):
		667
		668	=over 4
		669
		670	=item IO::AIO::READDIR_DENTS
		671
		672	When this flag is off, then the callback gets an arrayref with of names
		673	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		674	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		675	entry in more detail.
		676
		677	C<$name> is the name of the entry.
		678
		679	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		680
		681	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		682	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		683	C<IO::AIO::DT_WHT>.
		684
		685	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		686	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		687	scalars are read-only: you can not modify them.
		688
		689	C<$inode> is the inode number (which might not be exact on systems with 64
		690	bit inode numbers and 32 bit perls). This field has unspecified content on
		691	systems that do not deliver the inode information.
		692
		693	=item IO::AIO::READDIR_DIRS_FIRST
		694
		695	When this flag is set, then the names will be returned in an order where
		696	likely directories come first. This is useful when you need to quickly
		697	find directories, or you want to find all directories while avoiding to
		698	stat() each entry.
		699
		700	If the system returns type information in readdir, then this is used
		701	to find directories directly. Otherwise, likely directories are files
		702	beginning with ".", or otherwise files with no dots, of which files with
		703	short names are tried first.
		704
		705	=item IO::AIO::READDIR_STAT_ORDER
		706
		707	When this flag is set, then the names will be returned in an order
		708	suitable for stat()'ing each one. That is, when you plan to stat()
		709	all files in the given directory, then the returned order will likely
		710	be fastest.
		711
		712	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		713	the likely dirs come first, resulting in a less optimal stat order.
		714
		715	=item IO::AIO::READDIR_FOUND_UNKNOWN
		716
		717	This flag should not be set when calling C<aio_readdirx>. Instead, it
		718	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		719	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		720	C<$type>'s are known, which can be used to speed up some algorithms.
		721
		722	=back
		723
		724
		725	=item aio_load $path, $data, $callback->($status)
		726
		727	This is a composite request that tries to fully load the given file into
		728	memory. Status is the same as with aio_read.
		729
		730	=cut
		731
		732	sub aio_load($$;$) {
		733	my ($path, undef, $cb) = @_;
		734	my $data = \$_[1];
		735
		736	my $pri = aioreq_pri;
		737	my $grp = aio_group $cb;
		738
		739	aioreq_pri $pri;
		740	add $grp aio_open $path, O_RDONLY, 0, sub {
		741	my $fh = shift
		742	or return $grp->result (-1);
		743
		744	aioreq_pri $pri;
		745	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		746	$grp->result ($_[0]);
		747	};
		748	};
		749
		750	$grp
		751	}
		752
		753	=item aio_copy $srcpath, $dstpath, $callback->($status)
		754
		755	Try to copy the I<file> (directories not supported as either source or
		756	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		757	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		758
		759	This is a composite request that creates the destination file with
		760	mode 0200 and copies the contents of the source file into it using
		761	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		762	uid/gid, in that order.
		763
		764	If an error occurs, the partial destination file will be unlinked, if
		765	possible, except when setting atime, mtime, access mode and uid/gid, where
		766	errors are being ignored.
		767
		768	=cut
		769
		770	sub aio_copy($$;$) {
		771	my ($src, $dst, $cb) = @_;
		772
		773	my $pri = aioreq_pri;
		774	my $grp = aio_group $cb;
		775
		776	aioreq_pri $pri;
		777	add $grp aio_open $src, O_RDONLY, 0, sub {
		778	if (my $src_fh = $_[0]) {
		779	my @stat = stat $src_fh; # hmm, might block over nfs?
		780
		781	aioreq_pri $pri;
		782	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		783	if (my $dst_fh = $_[0]) {
		784	aioreq_pri $pri;
		785	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		786	if ($_[0] == $stat[7]) {
		787	$grp->result (0);
		788	close $src_fh;
		789
		790	my $ch = sub {
		791	aioreq_pri $pri;
		792	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		793	aioreq_pri $pri;
		794	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		795	aioreq_pri $pri;
		796	add $grp aio_close $dst_fh;
		797	}
		798	};
		799	};
		800
		801	aioreq_pri $pri;
		802	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		803	if ($_[0] < 0 && $! == ENOSYS) {
		804	aioreq_pri $pri;
		805	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		806	} else {
		807	$ch->();
		808	}
		809	};
		810	} else {
		811	$grp->result (-1);
		812	close $src_fh;
		813	close $dst_fh;
		814
		815	aioreq $pri;
		816	add $grp aio_unlink $dst;
		817	}
		818	};
		819	} else {
		820	$grp->result (-1);
		821	}
		822	},
		823
		824	} else {
		825	$grp->result (-1);
		826	}
		827	};
		828
		829	$grp
		830	}
		831
		832	=item aio_move $srcpath, $dstpath, $callback->($status)
		833
		834	Try to move the I<file> (directories not supported as either source or
		835	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		836	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		837
		838	This is a composite request that tries to rename(2) the file first; if
		839	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		840	that is successful, unlinks the C<$srcpath>.
		841
		842	=cut
		843
		844	sub aio_move($$;$) {
		845	my ($src, $dst, $cb) = @_;
		846
		847	my $pri = aioreq_pri;
		848	my $grp = aio_group $cb;
		849
		850	aioreq_pri $pri;
		851	add $grp aio_rename $src, $dst, sub {
		852	if ($_[0] && $! == EXDEV) {
		853	aioreq_pri $pri;
		854	add $grp aio_copy $src, $dst, sub {
		855	$grp->result ($_[0]);
		856
		857	if (!$_[0]) {
		858	aioreq_pri $pri;
		859	add $grp aio_unlink $src;
		860	}
		861	};
		862	} else {
		863	$grp->result ($_[0]);
		864	}
		865	};
		866
		867	$grp
		868	}
345		869
346	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	870	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
347		871
348	Scans a directory (similar to C<aio_readdir>) but additionally tries to	872	Scans a directory (similar to C<aio_readdir>) but additionally tries to
349	separate the entries of directory C<$path> into two sets of names, ones	873	efficiently separate the entries of directory C<$path> into two sets of
350	you can recurse into (directories or links to them), and ones you cannot	874	names, directories you can recurse into (directories), and ones you cannot
351	recurse into (everything else).	875	recurse into (everything else, including symlinks to directories).
352		876
353	C<aio_scandir> is a composite request that consists of many sub	877	C<aio_scandir> is a composite request that creates of many sub requests_
354	requests. C<$maxreq> specifies the maximum number of outstanding aio	878	C<$maxreq> specifies the maximum number of outstanding aio requests that
355	requests that this function generates. If it is C<< <= 0 >>, then a	879	this function generates. If it is C<< <= 0 >>, then a suitable default
356	suitable default will be chosen (currently 8).	880	will be chosen (currently 4).
357		881
358	On error, the callback is called without arguments, otherwise it receives	882	On error, the callback is called without arguments, otherwise it receives
359	two array-refs with path-relative entry names.	883	two array-refs with path-relative entry names.
360		884
361	Example:	885	Example:
…		…
368		892
369	Implementation notes.	893	Implementation notes.
370		894
371	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	895	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
372		896
		897	If readdir returns file type information, then this is used directly to
		898	find directories.
		899
373	After reading the directory, the modification time, size etc. of the	900	Otherwise, after reading the directory, the modification time, size etc.
374	directory before and after the readdir is checked, and if they match (and	901	of the directory before and after the readdir is checked, and if they
375	isn't the current time), the link count will be used to decide how many	902	match (and isn't the current time), the link count will be used to decide
376	entries are directories (if >= 2). Otherwise, no knowledge of the number	903	how many entries are directories (if >= 2). Otherwise, no knowledge of the
377	of subdirectories will be assumed.	904	number of subdirectories will be assumed.
378		905
379	Then entries will be sorted into likely directories (everything without	906	Then entries will be sorted into likely directories a non-initial dot
380	a non-initial dot currently) and likely non-directories (everything	907	currently) and likely non-directories (see C<aio_readdirx>). Then every
381	else). Then every entry plus an appended C</.> will be C<stat>'ed,	908	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
382	likely directories first. If that succeeds, it assumes that the entry	909	in order of their inode numbers. If that succeeds, it assumes that the
383	is a directory or a symlink to directory (which will be checked	910	entry is a directory or a symlink to directory (which will be checked
384	seperately). This is often faster than stat'ing the entry itself because	911	seperately). This is often faster than stat'ing the entry itself because
385	filesystems might detect the type of the entry without reading the inode	912	filesystems might detect the type of the entry without reading the inode
386	data (e.g. ext2fs filetype feature).	913	data (e.g. ext2fs filetype feature), even on systems that cannot return
		914	the filetype information on readdir.
387		915
388	If the known number of directories (link count - 2) has been reached, the	916	If the known number of directories (link count - 2) has been reached, the
389	rest of the entries is assumed to be non-directories.	917	rest of the entries is assumed to be non-directories.
390		918
391	This only works with certainty on POSIX (= UNIX) filesystems, which	919	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
395	as those tend to return 0 or 1 as link counts, which disables the	923	as those tend to return 0 or 1 as link counts, which disables the
396	directory counting heuristic.	924	directory counting heuristic.
397		925
398	=cut	926	=cut
399		927
400	sub aio_scandir($$$) {	928	sub aio_scandir($$;$) {
401	my ($path, $maxreq, $cb) = @_;	929	my ($path, $maxreq, $cb) = @_;
402		930
		931	my $pri = aioreq_pri;
		932
403	my $grp = aio_group;	933	my $grp = aio_group $cb;
404		934
405	$maxreq = 8 if $maxreq <= 0;	935	$maxreq = 4 if $maxreq <= 0;
406		936
407	# stat once	937	# stat once
		938	aioreq_pri $pri;
408	add $grp aio_stat $path, sub {	939	add $grp aio_stat $path, sub {
409	return $cb->() if $_[0];	940	return $grp->result () if $_[0];
410	my $now = time;	941	my $now = time;
411	my $hash1 = join ":", (stat _)[0,1,3,7,9];	942	my $hash1 = join ":", (stat _)[0,1,3,7,9];
412		943
413	# read the directory entries	944	# read the directory entries
		945	aioreq_pri $pri;
414	add $grp aio_readdir $path, sub {	946	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
415	my $entries = shift	947	my $entries = shift
416	or return $cb->();	948	or return $grp->result ();
417		949
418	# stat the dir another time	950	# stat the dir another time
		951	aioreq_pri $pri;
419	add $grp aio_stat $path, sub {	952	add $grp aio_stat $path, sub {
420	my $hash2 = join ":", (stat _)[0,1,3,7,9];	953	my $hash2 = join ":", (stat _)[0,1,3,7,9];
421		954
422	my $ndirs;	955	my $ndirs;
423		956
424	# take the slow route if anything looks fishy	957	# take the slow route if anything looks fishy
425	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	958	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
426	$ndirs = -1;	959	$ndirs = -1;
427	} else {	960	} else {
428	# if nlink == 2, we are finished	961	# if nlink == 2, we are finished
429	# on non-posix-fs's, we rely on nlink < 2	962	# for non-posix-fs's, we rely on nlink < 2
430	$ndirs = (stat _)[3] - 2	963	$ndirs = (stat _)[3] - 2
431	or return $cb->([], $entries);	964	or return $grp->result ([], $entries);
432	}	965	}
433		966
434	# sort into likely dirs and likely nondirs
435	# dirs == files without ".", short entries first
436	$entries = [map $_->[0],
437	sort { $b->[1] cmp $a->[1] }
438	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
439	@$entries];
440
441	my (@dirs, @nondirs);	967	my (@dirs, @nondirs);
442		968
443	my ($statcb, $schedcb);	969	my $statgrp = add $grp aio_group sub {
444	my $nreq = 0;	970	$grp->result (\@dirs, \@nondirs);
		971	};
445		972
446	$schedcb = sub {	973	limit $statgrp $maxreq;
447	if (@$entries) {	974	feed $statgrp sub {
448	if ($nreq < $maxreq) {	975	return unless @$entries;
449	my $ent = pop @$entries;	976	my $entry = shift @$entries;
		977
		978	aioreq_pri $pri;
		979	add $statgrp aio_stat "$path/$entry/.", sub {
		980	if ($_[0] < 0) {
		981	push @nondirs, $entry;
		982	} else {
		983	# need to check for real directory
		984	aioreq_pri $pri;
		985	add $statgrp aio_lstat "$path/$entry", sub {
		986	if (-d _) {
		987	push @dirs, $entry;
		988
		989	unless (--$ndirs) {
		990	push @nondirs, @$entries;
		991	feed $statgrp;
		992	}
		993	} else {
		994	push @nondirs, $entry;
		995	}
450	$nreq++;	996	}
451	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
452	}	997	}
453	} elsif (!$nreq) {
454	# finished
455	undef $statcb;
456	undef $schedcb;
457	$cb->(\@dirs, \@nondirs) if $cb;
458	undef $cb;
459	}	998	};
460	};	999	};
461	$statcb = sub {
462	my ($status, $entry) = @_;
463
464	if ($status < 0) {
465	$nreq--;
466	push @nondirs, $entry;
467	&$schedcb;
468	} else {
469	# need to check for real directory
470	add $grp aio_lstat "$path/$entry", sub {
471	$nreq--;
472
473	if (-d _) {
474	push @dirs, $entry;
475
476	if (!--$ndirs) {
477	push @nondirs, @$entries;
478	$entries = [];
479	}
480	} else {
481	push @nondirs, $entry;
482	}
483
484	&$schedcb;
485	}
486	}
487	};
488
489	&$schedcb while @$entries && $nreq < $maxreq;
490	};	1000	};
491	};	1001	};
492	};	1002	};
493		1003
494	$grp	1004	$grp
495	}	1005	}
496		1006
		1007	=item aio_rmtree $path, $callback->($status)
		1008
		1009	Delete a directory tree starting (and including) C<$path>, return the
		1010	status of the final C<rmdir> only. This is a composite request that
		1011	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		1012	everything else.
		1013
		1014	=cut
		1015
		1016	sub aio_rmtree;
		1017	sub aio_rmtree($;$) {
		1018	my ($path, $cb) = @_;
		1019
		1020	my $pri = aioreq_pri;
		1021	my $grp = aio_group $cb;
		1022
		1023	aioreq_pri $pri;
		1024	add $grp aio_scandir $path, 0, sub {
		1025	my ($dirs, $nondirs) = @_;
		1026
		1027	my $dirgrp = aio_group sub {
		1028	add $grp aio_rmdir $path, sub {
		1029	$grp->result ($_[0]);
		1030	};
		1031	};
		1032
		1033	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1034	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1035
		1036	add $grp $dirgrp;
		1037	};
		1038
		1039	$grp
		1040	}
		1041
		1042	=item aio_sync $callback->($status)
		1043
		1044	Asynchronously call sync and call the callback when finished.
		1045
497	=item aio_fsync $fh, $callback->($status)	1046	=item aio_fsync $fh, $callback->($status)
498		1047
499	Asynchronously call fsync on the given filehandle and call the callback	1048	Asynchronously call fsync on the given filehandle and call the callback
500	with the fsync result code.	1049	with the fsync result code.
501		1050
…		…
505	callback with the fdatasync result code.	1054	callback with the fdatasync result code.
506		1055
507	If this call isn't available because your OS lacks it or it couldn't be	1056	If this call isn't available because your OS lacks it or it couldn't be
508	detected, it will be emulated by calling C<fsync> instead.	1057	detected, it will be emulated by calling C<fsync> instead.
509		1058
		1059	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1060
		1061	Sync the data portion of the file specified by C<$offset> and C<$length>
		1062	to disk (but NOT the metadata), by calling the Linux-specific
		1063	sync_file_range call. If sync_file_range is not available or it returns
		1064	ENOSYS, then fdatasync or fsync is being substituted.
		1065
		1066	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1067	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1068	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1069	manpage for details.
		1070
		1071	=item aio_pathsync $path, $callback->($status)
		1072
		1073	This request tries to open, fsync and close the given path. This is a
		1074	composite request intended to sync directories after directory operations
		1075	(E.g. rename). This might not work on all operating systems or have any
		1076	specific effect, but usually it makes sure that directory changes get
		1077	written to disc. It works for anything that can be opened for read-only,
		1078	not just directories.
		1079
		1080	Future versions of this function might fall back to other methods when
		1081	C<fsync> on the directory fails (such as calling C<sync>).
		1082
		1083	Passes C<0> when everything went ok, and C<-1> on error.
		1084
		1085	=cut
		1086
		1087	sub aio_pathsync($;$) {
		1088	my ($path, $cb) = @_;
		1089
		1090	my $pri = aioreq_pri;
		1091	my $grp = aio_group $cb;
		1092
		1093	aioreq_pri $pri;
		1094	add $grp aio_open $path, O_RDONLY, 0, sub {
		1095	my ($fh) = @_;
		1096	if ($fh) {
		1097	aioreq_pri $pri;
		1098	add $grp aio_fsync $fh, sub {
		1099	$grp->result ($_[0]);
		1100
		1101	aioreq_pri $pri;
		1102	add $grp aio_close $fh;
		1103	};
		1104	} else {
		1105	$grp->result (-1);
		1106	}
		1107	};
		1108
		1109	$grp
		1110	}
		1111
		1112	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1113
		1114	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1115	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1116	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1117	scalar must only be modified in-place while an aio operation is pending on
		1118	it).
		1119
		1120	It calls the C<msync> function of your OS, if available, with the memory
		1121	area starting at C<$offset> in the string and ending C<$length> bytes
		1122	later. If C<$length> is negative, counts from the end, and if C<$length>
		1123	is C<undef>, then it goes till the end of the string. The flags can be
		1124	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1125	C<IO::AIO::MS_SYNC>.
		1126
		1127	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1128
		1129	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1130	scalars.
		1131
		1132	It touches (reads or writes) all memory pages in the specified
		1133	range inside the scalar. All caveats and parameters are the same
		1134	as for C<aio_msync>, above, except for flags, which must be either
		1135	C<0> (which reads all pages and ensures they are instantiated) or
		1136	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1137	writing an octet from it, which dirties the page).
		1138
		1139	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1140
		1141	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1142	scalars.
		1143
		1144	It reads in all the pages of the underlying storage into memory (if any)
		1145	and locks them, so they are not getting swapped/paged out or removed.
		1146
		1147	If C<$length> is undefined, then the scalar will be locked till the end.
		1148
		1149	On systems that do not implement C<mlock>, this function returns C<-1>
		1150	and sets errno to C<ENOSYS>.
		1151
		1152	Note that the corresponding C<munlock> is synchronous and is
		1153	documented under L<MISCELLANEOUS FUNCTIONS>.
		1154
		1155	Example: open a file, mmap and mlock it - both will be undone when
		1156	C<$data> gets destroyed.
		1157
		1158	open my $fh, "<", $path or die "$path: $!";
		1159	my $data;
		1160	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1161	aio_mlock $data; # mlock in background
		1162
		1163	=item aio_mlockall $flags, $callback->($status)
		1164
		1165	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1166	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1167
		1168	On systems that do not implement C<mlockall>, this function returns C<-1>
		1169	and sets errno to C<ENOSYS>.
		1170
		1171	Note that the corresponding C<munlockall> is synchronous and is
		1172	documented under L<MISCELLANEOUS FUNCTIONS>.
		1173
		1174	Example: asynchronously lock all current and future pages into memory.
		1175
		1176	aio_mlockall IO::AIO::MCL_FUTURE;
		1177
510	=item aio_group $callback->()	1178	=item aio_group $callback->(...)
511
512	[EXPERIMENTAL]
513		1179
514	This is a very special aio request: Instead of doing something, it is a	1180	This is a very special aio request: Instead of doing something, it is a
515	container for other aio requests, which is useful if you want to bundle	1181	container for other aio requests, which is useful if you want to bundle
516	many requests into a single, composite, request.	1182	many requests into a single, composite, request with a definite callback
		1183	and the ability to cancel the whole request with its subrequests.
517		1184
518	Returns an object of class L<IO::AIO::GRP>. See its documentation below	1185	Returns an object of class L<IO::AIO::GRP>. See its documentation below
519	for more info.	1186	for more info.
520		1187
521	Example:	1188	Example:
…		…
527	add $grp	1194	add $grp
528	(aio_stat ...),	1195	(aio_stat ...),
529	(aio_stat ...),	1196	(aio_stat ...),
530	...;	1197	...;
531		1198
		1199	=item aio_nop $callback->()
		1200
		1201	This is a special request - it does nothing in itself and is only used for
		1202	side effects, such as when you want to add a dummy request to a group so
		1203	that finishing the requests in the group depends on executing the given
		1204	code.
		1205
		1206	While this request does nothing, it still goes through the execution
		1207	phase and still requires a worker thread. Thus, the callback will not
		1208	be executed immediately but only after other requests in the queue have
		1209	entered their execution phase. This can be used to measure request
		1210	latency.
		1211
532	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() *NOT EXPORTED*	1212	=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED*
533		1213
534	Mainly used for debugging and benchmarking, this aio request puts one of	1214	Mainly used for debugging and benchmarking, this aio request puts one of
535	the request workers to sleep for the given time.	1215	the request workers to sleep for the given time.
536		1216
537	While it is theoretically handy to have simple I/O scheduling requests	1217	While it is theoretically handy to have simple I/O scheduling requests
538	like sleep and file handle readable/writable, the overhead this creates	1218	like sleep and file handle readable/writable, the overhead this creates is
539	is immense, so do not use this function except to put your application	1219	immense (it blocks a thread for a long time) so do not use this function
540	under artificial I/O pressure.	1220	except to put your application under artificial I/O pressure.
541		1221
542	=back	1222	=back
543		1223
544	=head2 IO::AIO::REQ CLASS	1224	=head2 IO::AIO::REQ CLASS
545		1225
546	All non-aggregate C<aio_*> functions return an object of this class when	1226	All non-aggregate C<aio_*> functions return an object of this class when
547	called in non-void context.	1227	called in non-void context.
548		1228
549	A request always moves through the following five states in its lifetime,
550	in order: B<ready> (request has been created, but has not been executed
551	yet), B<execute> (request is currently being executed), B<pending>
552	(request has been executed but callback has not been called yet),
553	B<result> (results are being processed synchronously, includes calling the
554	callback) and B<done> (request has reached the end of its lifetime and
555	holds no resources anymore).
556
557	=over 4	1229	=over 4
558		1230
559	=item $req->cancel	1231	=item cancel $req
560		1232
561	Cancels the request, if possible. Has the effect of skipping execution	1233	Cancels the request, if possible. Has the effect of skipping execution
562	when entering the B<execute> state and skipping calling the callback when	1234	when entering the B<execute> state and skipping calling the callback when
563	entering the the B<result> state, but will leave the request otherwise	1235	entering the the B<result> state, but will leave the request otherwise
564	untouched. That means that requests that currently execute will not be	1236	untouched (with the exception of readdir). That means that requests that
565	stopped and resources held by the request will not be freed prematurely.	1237	currently execute will not be stopped and resources held by the request
		1238	will not be freed prematurely.
		1239
		1240	=item cb $req $callback->(...)
		1241
		1242	Replace (or simply set) the callback registered to the request.
566		1243
567	=back	1244	=back
568		1245
569	=head2 IO::AIO::GRP CLASS	1246	=head2 IO::AIO::GRP CLASS
570		1247
…		…
585	You add requests by calling the C<add> method with one or more	1262	You add requests by calling the C<add> method with one or more
586	C<IO::AIO::REQ> objects:	1263	C<IO::AIO::REQ> objects:
587		1264
588	$grp->add (aio_unlink "...");	1265	$grp->add (aio_unlink "...");
589		1266
590	add $grp aio_stat "...", sub { ... };	1267	add $grp aio_stat "...", sub {
		1268	$_[0] or return $grp->result ("error");
		1269
		1270	# add another request dynamically, if first succeeded
		1271	add $grp aio_open "...", sub {
		1272	$grp->result ("ok");
		1273	};
		1274	};
591		1275
592	This makes it very easy to create composite requests (see the source of	1276	This makes it very easy to create composite requests (see the source of
593	C<aio_move> for an application) that work and feel like simple requests.	1277	C<aio_move> for an application) that work and feel like simple requests.
594		1278
		1279	=over 4
		1280
595	The IO::AIO::GRP objects will be cleaned up during calls to	1281	=item * The IO::AIO::GRP objects will be cleaned up during calls to
596	C<IO::AIO::poll_cb>, just like any other request.	1282	C<IO::AIO::poll_cb>, just like any other request.
597		1283
598	They can be canceled like any other request. Canceling will cancel not	1284	=item * They can be canceled like any other request. Canceling will cancel not
599	just the request itself, but also all requests it contains.	1285	only the request itself, but also all requests it contains.
600		1286
601	They can also can also be added to other IO::AIO::GRP objects.	1287	=item * They can also can also be added to other IO::AIO::GRP objects.
		1288
		1289	=item * You must not add requests to a group from within the group callback (or
		1290	any later time).
		1291
		1292	=back
602		1293
603	Their lifetime, simplified, looks like this: when they are empty, they	1294	Their lifetime, simplified, looks like this: when they are empty, they
604	will finish very quickly. If they contain only requests that are in the	1295	will finish very quickly. If they contain only requests that are in the
605	C<done> state, they will also finish. Otherwise they will continue to	1296	C<done> state, they will also finish. Otherwise they will continue to
606	exist.	1297	exist.
607		1298
		1299	That means after creating a group you have some time to add requests
		1300	(precisely before the callback has been invoked, which is only done within
		1301	the C<poll_cb>). And in the callbacks of those requests, you can add
		1302	further requests to the group. And only when all those requests have
		1303	finished will the the group itself finish.
		1304
608	=over 4	1305	=over 4
609		1306
		1307	=item add $grp ...
		1308
610	=item $grp->add (...)	1309	=item $grp->add (...)
611		1310
612	=item add $grp ...	1311	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		1312	be added, including other groups, as long as you do not create circular
		1313	dependencies.
613		1314
614	Add one or more	1315	Returns all its arguments.
615	Cancels the request, if possible. Has the effect of skipping execution	1316
616	when entering the B<execute> state and skipping calling the callback when	1317	=item $grp->cancel_subs
617	entering the the B<result> state, but will leave the request otherwise	1318
618	untouched. That means that requests that currently execute will not be	1319	Cancel all subrequests and clears any feeder, but not the group request
619	stopped and resources held by the request will not be freed prematurely.	1320	itself. Useful when you queued a lot of events but got a result early.
		1321
		1322	The group request will finish normally (you cannot add requests to the
		1323	group).
		1324
		1325	=item $grp->result (...)
		1326
		1327	Set the result value(s) that will be passed to the group callback when all
		1328	subrequests have finished and set the groups errno to the current value
		1329	of errno (just like calling C<errno> without an error number). By default,
		1330	no argument will be passed and errno is zero.
		1331
		1332	=item $grp->errno ([$errno])
		1333
		1334	Sets the group errno value to C<$errno>, or the current value of errno
		1335	when the argument is missing.
		1336
		1337	Every aio request has an associated errno value that is restored when
		1338	the callback is invoked. This method lets you change this value from its
		1339	default (0).
		1340
		1341	Calling C<result> will also set errno, so make sure you either set C<$!>
		1342	before the call to C<result>, or call c<errno> after it.
		1343
		1344	=item feed $grp $callback->($grp)
		1345
		1346	Sets a feeder/generator on this group: every group can have an attached
		1347	generator that generates requests if idle. The idea behind this is that,
		1348	although you could just queue as many requests as you want in a group,
		1349	this might starve other requests for a potentially long time. For example,
		1350	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
		1351	delaying any later requests for a long time.
		1352
		1353	To avoid this, and allow incremental generation of requests, you can
		1354	instead a group and set a feeder on it that generates those requests. The
		1355	feed callback will be called whenever there are few enough (see C<limit>,
		1356	below) requests active in the group itself and is expected to queue more
		1357	requests.
		1358
		1359	The feed callback can queue as many requests as it likes (i.e. C<add> does
		1360	not impose any limits).
		1361
		1362	If the feed does not queue more requests when called, it will be
		1363	automatically removed from the group.
		1364
		1365	If the feed limit is C<0> when this method is called, it will be set to
		1366	C<2> automatically.
		1367
		1368	Example:
		1369
		1370	# stat all files in @files, but only ever use four aio requests concurrently:
		1371
		1372	my $grp = aio_group sub { print "finished\n" };
		1373	limit $grp 4;
		1374	feed $grp sub {
		1375	my $file = pop @files
		1376	or return;
		1377
		1378	add $grp aio_stat $file, sub { ... };
		1379	};
		1380
		1381	=item limit $grp $num
		1382
		1383	Sets the feeder limit for the group: The feeder will be called whenever
		1384	the group contains less than this many requests.
		1385
		1386	Setting the limit to C<0> will pause the feeding process.
		1387
		1388	The default value for the limit is C<0>, but note that setting a feeder
		1389	automatically bumps it up to C<2>.
620		1390
621	=back	1391	=back
622		1392
623	=head2 SUPPORT FUNCTIONS	1393	=head2 SUPPORT FUNCTIONS
624		1394
		1395	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1396
625	=over 4	1397	=over 4
626		1398
627	=item $fileno = IO::AIO::poll_fileno	1399	=item $fileno = IO::AIO::poll_fileno
628		1400
629	Return the I<request result pipe file descriptor>. This filehandle must be	1401	Return the I<request result pipe file descriptor>. This filehandle must be
630	polled for reading by some mechanism outside this module (e.g. Event or	1402	polled for reading by some mechanism outside this module (e.g. EV, Glib,
631	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1403	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
632	to call C<poll_cb> to check the results.	1404	you have to call C<poll_cb> to check the results.
633		1405
634	See C<poll_cb> for an example.	1406	See C<poll_cb> for an example.
635		1407
636	=item IO::AIO::poll_cb	1408	=item IO::AIO::poll_cb
637		1409
638	Process all outstanding events on the result pipe. You have to call this	1410	Process some outstanding events on the result pipe. You have to call this
639	regularly. Returns the number of events processed. Returns immediately	1411	regularly. Returns C<0> if all events could be processed, or C<-1> if it
640	when no events are outstanding.	1412	returned earlier for whatever reason. Returns immediately when no events
		1413	are outstanding. The amount of events processed depends on the settings of
		1414	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1415
		1416	If not all requests were processed for whatever reason, the filehandle
		1417	will still be ready when C<poll_cb> returns, so normally you don't have to
		1418	do anything special to have it called later.
641		1419
642	Example: Install an Event watcher that automatically calls	1420	Example: Install an Event watcher that automatically calls
643	IO::AIO::poll_cb with high priority:	1421	IO::AIO::poll_cb with high priority (more examples can be found in the
		1422	SYNOPSIS section, at the top of this document):
644		1423
645	Event->io (fd => IO::AIO::poll_fileno,	1424	Event->io (fd => IO::AIO::poll_fileno,
646	poll => 'r', async => 1,	1425	poll => 'r', async => 1,
647	cb => \&IO::AIO::poll_cb);	1426	cb => \&IO::AIO::poll_cb);
648		1427
649	=item IO::AIO::poll_wait	1428	=item IO::AIO::poll_wait
650		1429
		1430	If there are any outstanding requests and none of them in the result
651	Wait till the result filehandle becomes ready for reading (simply does a	1431	phase, wait till the result filehandle becomes ready for reading (simply
652	C<select> on the filehandle. This is useful if you want to synchronously wait	1432	does a C<select> on the filehandle. This is useful if you want to
653	for some requests to finish).	1433	synchronously wait for some requests to finish).
654		1434
655	See C<nreqs> for an example.	1435	See C<nreqs> for an example.
656		1436
		1437	=item IO::AIO::poll
		1438
		1439	Waits until some requests have been handled.
		1440
		1441	Returns the number of requests processed, but is otherwise strictly
		1442	equivalent to:
		1443
		1444	IO::AIO::poll_wait, IO::AIO::poll_cb
		1445
657	=item IO::AIO::nreqs	1446	=item IO::AIO::flush
658		1447
659	Returns the number of requests currently outstanding (i.e. for which their	1448	Wait till all outstanding AIO requests have been handled.
660	callback has not been invoked yet).
661		1449
662	Example: wait till there are no outstanding requests anymore:	1450	Strictly equivalent to:
663		1451
664	IO::AIO::poll_wait, IO::AIO::poll_cb	1452	IO::AIO::poll_wait, IO::AIO::poll_cb
665	while IO::AIO::nreqs;	1453	while IO::AIO::nreqs;
666		1454
667	=item IO::AIO::flush	1455	=item IO::AIO::max_poll_reqs $nreqs
668		1456
669	Wait till all outstanding AIO requests have been handled.	1457	=item IO::AIO::max_poll_time $seconds
670		1458
671	Strictly equivalent to:	1459	These set the maximum number of requests (default C<0>, meaning infinity)
		1460	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1461	the maximum amount of time (default C<0>, meaning infinity) spent in
		1462	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1463	of time C<poll_cb> is allowed to use).
672		1464
673	IO::AIO::poll_wait, IO::AIO::poll_cb	1465	Setting C<max_poll_time> to a non-zero value creates an overhead of one
674	while IO::AIO::nreqs;	1466	syscall per request processed, which is not normally a problem unless your
		1467	callbacks are really really fast or your OS is really really slow (I am
		1468	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
675		1469
676	=item IO::AIO::poll	1470	Setting these is useful if you want to ensure some level of
		1471	interactiveness when perl is not fast enough to process all requests in
		1472	time.
677		1473
678	Waits until some requests have been handled.	1474	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
679		1475
680	Strictly equivalent to:	1476	Example: Install an Event watcher that automatically calls
		1477	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1478	program get the CPU sometimes even under high AIO load.
681		1479
682	IO::AIO::poll_wait, IO::AIO::poll_cb	1480	# try not to spend much more than 0.1s in poll_cb
683	if IO::AIO::nreqs;	1481	IO::AIO::max_poll_time 0.1;
		1482
		1483	# use a low priority so other tasks have priority
		1484	Event->io (fd => IO::AIO::poll_fileno,
		1485	poll => 'r', nice => 1,
		1486	cb => &IO::AIO::poll_cb);
		1487
		1488	=back
		1489
		1490	=head3 CONTROLLING THE NUMBER OF THREADS
		1491
		1492	=over
684		1493
685	=item IO::AIO::min_parallel $nthreads	1494	=item IO::AIO::min_parallel $nthreads
686		1495
687	Set the minimum number of AIO threads to C<$nthreads>. The current default	1496	Set the minimum number of AIO threads to C<$nthreads>. The current
688	is C<4>, which means four asynchronous operations can be done at one time	1497	default is C<8>, which means eight asynchronous operations can execute
689	(the number of outstanding operations, however, is unlimited).	1498	concurrently at any one time (the number of outstanding requests,
		1499	however, is unlimited).
690		1500
691	IO::AIO starts threads only on demand, when an AIO request is queued and	1501	IO::AIO starts threads only on demand, when an AIO request is queued and
692	no free thread exists.	1502	no free thread exists. Please note that queueing up a hundred requests can
		1503	create demand for a hundred threads, even if it turns out that everything
		1504	is in the cache and could have been processed faster by a single thread.
693		1505
694	It is recommended to keep the number of threads low, as some Linux	1506	It is recommended to keep the number of threads relatively low, as some
695	kernel versions will scale negatively with the number of threads (higher	1507	Linux kernel versions will scale negatively with the number of threads
696	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1508	(higher parallelity => MUCH higher latency). With current Linux 2.6
697	threads should be fine.	1509	versions, 4-32 threads should be fine.
698		1510
699	Under most circumstances you don't need to call this function, as the	1511	Under most circumstances you don't need to call this function, as the
700	module selects a default that is suitable for low to moderate load.	1512	module selects a default that is suitable for low to moderate load.
701		1513
702	=item IO::AIO::max_parallel $nthreads	1514	=item IO::AIO::max_parallel $nthreads
…		…
711	This module automatically runs C<max_parallel 0> at program end, to ensure	1523	This module automatically runs C<max_parallel 0> at program end, to ensure
712	that all threads are killed and that there are no outstanding requests.	1524	that all threads are killed and that there are no outstanding requests.
713		1525
714	Under normal circumstances you don't need to call this function.	1526	Under normal circumstances you don't need to call this function.
715		1527
		1528	=item IO::AIO::max_idle $nthreads
		1529
		1530	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1531	threads that did not get a request to process within 10 seconds). That
		1532	means if a thread becomes idle while C<$nthreads> other threads are also
		1533	idle, it will free its resources and exit.
		1534
		1535	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1536	to allow for extremely high load situations, but want to free resources
		1537	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1538
		1539	The default is probably ok in most situations, especially if thread
		1540	creation is fast. If thread creation is very slow on your system you might
		1541	want to use larger values.
		1542
716	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1543	=item IO::AIO::max_outstanding $maxreqs
		1544
		1545	This is a very bad function to use in interactive programs because it
		1546	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1547	use an C<aio_group> together with a feed callback.
717		1548
718	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1549	Sets the maximum number of outstanding requests to C<$nreqs>. If you
719	try to queue up more than this number of requests, the caller will block until	1550	do queue up more than this number of requests, the next call to the
720	some requests have been handled.	1551	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1552	function will block until the limit is no longer exceeded.
721		1553
722	The default is very large, so normally there is no practical limit. If you	1554	The default value is very large, so there is no practical limit on the
723	queue up many requests in a loop it often improves speed if you set	1555	number of outstanding requests.
724	this to a relatively low number, such as C<100>.
725		1556
726	Under normal circumstances you don't need to call this function.	1557	You can still queue as many requests as you want. Therefore,
		1558	C<max_outstanding> is mainly useful in simple scripts (with low values) or
		1559	as a stop gap to shield against fatal memory overflow (with large values).
727		1560
728	=back	1561	=back
729		1562
		1563	=head3 STATISTICAL INFORMATION
		1564
		1565	=over
		1566
		1567	=item IO::AIO::nreqs
		1568
		1569	Returns the number of requests currently in the ready, execute or pending
		1570	states (i.e. for which their callback has not been invoked yet).
		1571
		1572	Example: wait till there are no outstanding requests anymore:
		1573
		1574	IO::AIO::poll_wait, IO::AIO::poll_cb
		1575	while IO::AIO::nreqs;
		1576
		1577	=item IO::AIO::nready
		1578
		1579	Returns the number of requests currently in the ready state (not yet
		1580	executed).
		1581
		1582	=item IO::AIO::npending
		1583
		1584	Returns the number of requests currently in the pending state (executed,
		1585	but not yet processed by poll_cb).
		1586
		1587	=back
		1588
		1589	=head3 MISCELLANEOUS FUNCTIONS
		1590
		1591	IO::AIO implements some functions that might be useful, but are not
		1592	asynchronous.
		1593
		1594	=over 4
		1595
		1596	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1597
		1598	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1599	but is blocking (this makes most sense if you know the input data is
		1600	likely cached already and the output filehandle is set to non-blocking
		1601	operations).
		1602
		1603	Returns the number of bytes copied, or C<-1> on error.
		1604
		1605	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1606
		1607	Simply calls the C<posix_fadvise> function (see its
		1608	manpage for details). The following advice constants are
		1609	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1610	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1611	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1612
		1613	On systems that do not implement C<posix_fadvise>, this function returns
		1614	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1615
		1616	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1617
		1618	Simply calls the C<posix_madvise> function (see its
		1619	manpage for details). The following advice constants are
		1620	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1621	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1622
		1623	On systems that do not implement C<posix_madvise>, this function returns
		1624	ENOSYS, otherwise the return value of C<posix_madvise>.
		1625
		1626	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1627
		1628	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1629	$scalar (see its manpage for details). The following protect
		1630	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1631	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1632
		1633	On systems that do not implement C<mprotect>, this function returns
		1634	ENOSYS, otherwise the return value of C<mprotect>.
		1635
		1636	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1637
		1638	Memory-maps a file (or anonymous memory range) and attaches it to the
		1639	given C<$scalar>, which will act like a string scalar.
		1640
		1641	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1642	change the string length, and most read-only operations such as copying it
		1643	or searching it with regexes and so on.
		1644
		1645	Anything else is unsafe and will, at best, result in memory leaks.
		1646
		1647	The memory map associated with the C<$scalar> is automatically removed
		1648	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1649	C<IO::AIO::munmap> functions are called.
		1650
		1651	This calls the C<mmap>(2) function internally. See your system's manual
		1652	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1653
		1654	The C<$length> must be larger than zero and smaller than the actual
		1655	filesize.
		1656
		1657	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1658	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1659
		1660	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1661	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1662	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1663	(which is set to C<MAP_ANON> if your system only provides this
		1664	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1665	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1666	C<IO::AIO::MAP_NONBLOCK>
		1667
		1668	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1669
		1670	C<$offset> is the offset from the start of the file - it generally must be
		1671	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1672
		1673	Example:
		1674
		1675	use Digest::MD5;
		1676	use IO::AIO;
		1677
		1678	open my $fh, "<verybigfile"
		1679	or die "$!";
		1680
		1681	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1682	or die "verybigfile: $!";
		1683
		1684	my $fast_md5 = md5 $data;
		1685
		1686	=item IO::AIO::munmap $scalar
		1687
		1688	Removes a previous mmap and undefines the C<$scalar>.
		1689
		1690	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1691
		1692	Calls the C<munlock> function, undoing the effects of a previous
		1693	C<aio_mlock> call (see its description for details).
		1694
		1695	=item IO::AIO::munlockall
		1696
		1697	Calls the C<munlockall> function.
		1698
		1699	On systems that do not implement C<munlockall>, this function returns
		1700	ENOSYS, otherwise the return value of C<munlockall>.
		1701
		1702	=back
		1703
730	=cut	1704	=cut
731		1705
732	# support function to convert a fd into a perl filehandle
733	sub _fd2fh {
734	return undef if $_[0] < 0;
735
736	# try to generate nice filehandles
737	my $sym = "IO::AIO::fd#$_[0]";
738	local *$sym;
739
740	open *$sym, "+<&=$_[0]" # usually works under any unix
741	or open *$sym, "<&=$_[0]" # cygwin needs this
742	or open *$sym, ">&=$_[0]" # or this
743	or return undef;
744
745	*$sym
746	}
747
748	min_parallel 4;	1706	min_parallel 8;
749		1707
750	END {	1708	END { flush }
751	max_parallel 0;
752	}
753		1709
754	1;	1710	1;
		1711
		1712	=head1 EVENT LOOP INTEGRATION
		1713
		1714	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1715	automatically into many event loops:
		1716
		1717	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1718	use AnyEvent::AIO;
		1719
		1720	You can also integrate IO::AIO manually into many event loops, here are
		1721	some examples of how to do this:
		1722
		1723	# EV integration
		1724	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1725
		1726	# Event integration
		1727	Event->io (fd => IO::AIO::poll_fileno,
		1728	poll => 'r',
		1729	cb => \&IO::AIO::poll_cb);
		1730
		1731	# Glib/Gtk2 integration
		1732	add_watch Glib::IO IO::AIO::poll_fileno,
		1733	in => sub { IO::AIO::poll_cb; 1 };
		1734
		1735	# Tk integration
		1736	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1737	readable => \&IO::AIO::poll_cb);
		1738
		1739	# Danga::Socket integration
		1740	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1741	\&IO::AIO::poll_cb);
755		1742
756	=head2 FORK BEHAVIOUR	1743	=head2 FORK BEHAVIOUR
757		1744
758	This module should do "the right thing" when the process using it forks:	1745	This module should do "the right thing" when the process using it forks:
759		1746
760	Before the fork, IO::AIO enters a quiescent state where no requests	1747	Before the fork, IO::AIO enters a quiescent state where no requests
761	can be added in other threads and no results will be processed. After	1748	can be added in other threads and no results will be processed. After
762	the fork the parent simply leaves the quiescent state and continues	1749	the fork the parent simply leaves the quiescent state and continues
763	request/result processing, while the child clears the request/result	1750	request/result processing, while the child frees the request/result queue
764	queue (so the requests started before the fork will only be handled in	1751	(so that the requests started before the fork will only be handled in the
765	the parent). Threads will be started on demand until the limit ste in the	1752	parent). Threads will be started on demand until the limit set in the
766	parent process has been reached again.	1753	parent process has been reached again.
767		1754
768	In short: the parent will, after a short pause, continue as if fork had	1755	In short: the parent will, after a short pause, continue as if fork had
769	not been called, while the child will act as if IO::AIO has not been used	1756	not been called, while the child will act as if IO::AIO has not been used
770	yet.	1757	yet.
771		1758
		1759	=head2 MEMORY USAGE
		1760
		1761	Per-request usage:
		1762
		1763	Each aio request uses - depending on your architecture - around 100-200
		1764	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1765	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1766	scalars and other data passed into aio requests will also be locked and
		1767	will consume memory till the request has entered the done state.
		1768
		1769	This is not awfully much, so queuing lots of requests is not usually a
		1770	problem.
		1771
		1772	Per-thread usage:
		1773
		1774	In the execution phase, some aio requests require more memory for
		1775	temporary buffers, and each thread requires a stack and other data
		1776	structures (usually around 16k-128k, depending on the OS).
		1777
		1778	=head1 KNOWN BUGS
		1779
		1780	Known bugs will be fixed in the next release.
		1781
772	=head1 SEE ALSO	1782	=head1 SEE ALSO
773		1783
774	L<Coro>, L<Linux::AIO> (obsolete).	1784	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1785	more natural syntax.
775		1786
776	=head1 AUTHOR	1787	=head1 AUTHOR
777		1788
778	Marc Lehmann <schmorp@schmorp.de>	1789	Marc Lehmann <schmorp@schmorp.de>
779	http://home.schmorp.de/	1790	http://home.schmorp.de/

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