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Revision 1.57 by root, Sun Oct 22 01:28:31 2006 UTC vs.
Revision 1.184 by root, Mon Nov 1 22:03:43 2010 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
10	my ($fh) = @_;	10	my $fh = shift
		11	or die "/etc/passwd: $!";
11	...	12	...
12	};	13	};
13		14
14	aio_unlink "/tmp/file", sub { };	15	aio_unlink "/tmp/file", sub { };
15		16
…		…
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 = '3.7';
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
…		…
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
261	This call tries to make use of a native C<sendfile> syscall to provide	433	This call tries to make use of a native C<sendfile> syscall to provide
262	zero-copy operation. For this to work, C<$out_fh> should refer to a	434	zero-copy operation. For this to work, C<$out_fh> should refer to a
263	socket, and C<$in_fh> should refer to mmap'able file.	435	socket, and C<$in_fh> should refer to an mmap'able file.
264		436
265	If the native sendfile call fails or is not implemented, it will be	437	If a native sendfile cannot be found or it fails with C<ENOSYS>,
		438	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,
266	emulated, so you can call C<aio_sendfile> on any type of filehandle	439	it will be emulated, so you can call C<aio_sendfile> on any type of
267	regardless of the limitations of the operating system.	440	filehandle regardless of the limitations of the operating system.
268		441
269	Please note, however, that C<aio_sendfile> can read more bytes from	442	Please note, however, that C<aio_sendfile> can read more bytes from
270	C<$in_fh> than are written, and there is no way to find out how many	443	C<$in_fh> than are written, and there is no way to find out how many
271	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	444	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
272	provides the number of bytes written to C<$out_fh>. Only if the result	445	provides the number of bytes written to C<$out_fh>. Only if the result
273	value equals C<$length> one can assume that C<$length> bytes have been	446	value equals C<$length> one can assume that C<$length> bytes have been
274	read.	447	read.
		448
275		449
276	=item aio_readahead $fh,$offset,$length, $callback->($retval)	450	=item aio_readahead $fh,$offset,$length, $callback->($retval)
277		451
278	C<aio_readahead> populates the page cache with data from a file so that	452	C<aio_readahead> populates the page cache with data from a file so that
279	subsequent reads from that file will not block on disk I/O. The C<$offset>	453	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
285	file. The current file offset of the file is left unchanged.	459	file. The current file offset of the file is left unchanged.
286		460
287	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	461	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
288	emulated by simply reading the data, which would have a similar effect.	462	emulated by simply reading the data, which would have a similar effect.
289		463
		464
290	=item aio_stat $fh_or_path, $callback->($status)	465	=item aio_stat $fh_or_path, $callback->($status)
291		466
292	=item aio_lstat $fh, $callback->($status)	467	=item aio_lstat $fh, $callback->($status)
293		468
294	Works like perl's C<stat> or C<lstat> in void context. The callback will	469	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
307	aio_stat "/etc/passwd", sub {	482	aio_stat "/etc/passwd", sub {
308	$_[0] and die "stat failed: $!";	483	$_[0] and die "stat failed: $!";
309	print "size is ", -s _, "\n";	484	print "size is ", -s _, "\n";
310	};	485	};
311		486
		487
		488	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		489
		490	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		491	whether a file handle or path was passed.
		492
		493	On success, the callback is passed a hash reference with the following
		494	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		495	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		496	is passed.
		497
		498	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		499	C<ST_NOSUID>.
		500
		501	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		502	their correct value when available, or to C<0> on systems that do
		503	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		504	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		505	C<ST_NODIRATIME> and C<ST_RELATIME>.
		506
		507	Example: stat C</wd> and dump out the data if successful.
		508
		509	aio_statvfs "/wd", sub {
		510	my $f = $_[0]
		511	or die "statvfs: $!";
		512
		513	use Data::Dumper;
		514	say Dumper $f;
		515	};
		516
		517	# result:
		518	{
		519	bsize => 1024,
		520	bfree => 4333064312,
		521	blocks => 10253828096,
		522	files => 2050765568,
		523	flag => 4096,
		524	favail => 2042092649,
		525	bavail => 4333064312,
		526	ffree => 2042092649,
		527	namemax => 255,
		528	frsize => 1024,
		529	fsid => 1810
		530	}
		531
		532
		533	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		534
		535	Works like perl's C<utime> function (including the special case of $atime
		536	and $mtime being undef). Fractional times are supported if the underlying
		537	syscalls support them.
		538
		539	When called with a pathname, uses utimes(2) if available, otherwise
		540	utime(2). If called on a file descriptor, uses futimes(2) if available,
		541	otherwise returns ENOSYS, so this is not portable.
		542
		543	Examples:
		544
		545	# set atime and mtime to current time (basically touch(1)):
		546	aio_utime "path", undef, undef;
		547	# set atime to current time and mtime to beginning of the epoch:
		548	aio_utime "path", time, undef; # undef==0
		549
		550
		551	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		552
		553	Works like perl's C<chown> function, except that C<undef> for either $uid
		554	or $gid is being interpreted as "do not change" (but -1 can also be used).
		555
		556	Examples:
		557
		558	# same as "chown root path" in the shell:
		559	aio_chown "path", 0, -1;
		560	# same as above:
		561	aio_chown "path", 0, undef;
		562
		563
		564	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		565
		566	Works like truncate(2) or ftruncate(2).
		567
		568
		569	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		570
		571	Works like perl's C<chmod> function.
		572
		573
312	=item aio_unlink $pathname, $callback->($status)	574	=item aio_unlink $pathname, $callback->($status)
313		575
314	Asynchronously unlink (delete) a file and call the callback with the	576	Asynchronously unlink (delete) a file and call the callback with the
315	result code.	577	result code.
316		578
		579
		580	=item aio_mknod $path, $mode, $dev, $callback->($status)
		581
		582	[EXPERIMENTAL]
		583
		584	Asynchronously create a device node (or fifo). See mknod(2).
		585
		586	The only (POSIX-) portable way of calling this function is:
		587
		588	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		589
		590
317	=item aio_link $srcpath, $dstpath, $callback->($status)	591	=item aio_link $srcpath, $dstpath, $callback->($status)
318		592
319	Asynchronously create a new link to the existing object at C<$srcpath> at	593	Asynchronously create a new link to the existing object at C<$srcpath> at
320	the path C<$dstpath> and call the callback with the result code.	594	the path C<$dstpath> and call the callback with the result code.
321		595
		596
322	=item aio_symlink $srcpath, $dstpath, $callback->($status)	597	=item aio_symlink $srcpath, $dstpath, $callback->($status)
323		598
324	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	599	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
325	the path C<$dstpath> and call the callback with the result code.	600	the path C<$dstpath> and call the callback with the result code.
326		601
		602
		603	=item aio_readlink $path, $callback->($link)
		604
		605	Asynchronously read the symlink specified by C<$path> and pass it to
		606	the callback. If an error occurs, nothing or undef gets passed to the
		607	callback.
		608
		609
327	=item aio_rename $srcpath, $dstpath, $callback->($status)	610	=item aio_rename $srcpath, $dstpath, $callback->($status)
328		611
329	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	612	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
330	rename(2) and call the callback with the result code.	613	rename(2) and call the callback with the result code.
331		614
		615
		616	=item aio_mkdir $pathname, $mode, $callback->($status)
		617
		618	Asynchronously mkdir (create) a directory and call the callback with
		619	the result code. C<$mode> will be modified by the umask at the time the
		620	request is executed, so do not change your umask.
		621
		622
332	=item aio_rmdir $pathname, $callback->($status)	623	=item aio_rmdir $pathname, $callback->($status)
333		624
334	Asynchronously rmdir (delete) a directory and call the callback with the	625	Asynchronously rmdir (delete) a directory and call the callback with the
335	result code.	626	result code.
		627
336		628
337	=item aio_readdir $pathname, $callback->($entries)	629	=item aio_readdir $pathname, $callback->($entries)
338		630
339	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	631	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
340	directory (i.e. opendir + readdir + closedir). The entries will not be	632	directory (i.e. opendir + readdir + closedir). The entries will not be
341	sorted, and will B<NOT> include the C<.> and C<..> entries.	633	sorted, and will B<NOT> include the C<.> and C<..> entries.
342		634
343	The callback a single argument which is either C<undef> or an array-ref	635	The callback is passed a single argument which is either C<undef> or an
344	with the filenames.	636	array-ref with the filenames.
		637
		638
		639	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		640
		641	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		642	behaviour and output format. In case of an error, C<$entries> will be
		643	C<undef>.
		644
		645	The flags are a combination of the following constants, ORed together (the
		646	flags will also be passed to the callback, possibly modified):
		647
		648	=over 4
		649
		650	=item IO::AIO::READDIR_DENTS
		651
		652	When this flag is off, then the callback gets an arrayref with of names
		653	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		654	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		655	entry in more detail.
		656
		657	C<$name> is the name of the entry.
		658
		659	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		660
		661	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		662	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		663	C<IO::AIO::DT_WHT>.
		664
		665	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		666	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		667	scalars are read-only: you can not modify them.
		668
		669	C<$inode> is the inode number (which might not be exact on systems with 64
		670	bit inode numbers and 32 bit perls). This field has unspecified content on
		671	systems that do not deliver the inode information.
		672
		673	=item IO::AIO::READDIR_DIRS_FIRST
		674
		675	When this flag is set, then the names will be returned in an order where
		676	likely directories come first. This is useful when you need to quickly
		677	find directories, or you want to find all directories while avoiding to
		678	stat() each entry.
		679
		680	If the system returns type information in readdir, then this is used
		681	to find directories directly. Otherwise, likely directories are files
		682	beginning with ".", or otherwise files with no dots, of which files with
		683	short names are tried first.
		684
		685	=item IO::AIO::READDIR_STAT_ORDER
		686
		687	When this flag is set, then the names will be returned in an order
		688	suitable for stat()'ing each one. That is, when you plan to stat()
		689	all files in the given directory, then the returned order will likely
		690	be fastest.
		691
		692	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		693	the likely dirs come first, resulting in a less optimal stat order.
		694
		695	=item IO::AIO::READDIR_FOUND_UNKNOWN
		696
		697	This flag should not be set when calling C<aio_readdirx>. Instead, it
		698	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		699	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		700	C<$type>'s are known, which can be used to speed up some algorithms.
		701
		702	=back
		703
		704
		705	=item aio_load $path, $data, $callback->($status)
		706
		707	This is a composite request that tries to fully load the given file into
		708	memory. Status is the same as with aio_read.
		709
		710	=cut
		711
		712	sub aio_load($$;$) {
		713	my ($path, undef, $cb) = @_;
		714	my $data = \$_[1];
		715
		716	my $pri = aioreq_pri;
		717	my $grp = aio_group $cb;
		718
		719	aioreq_pri $pri;
		720	add $grp aio_open $path, O_RDONLY, 0, sub {
		721	my $fh = shift
		722	or return $grp->result (-1);
		723
		724	aioreq_pri $pri;
		725	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		726	$grp->result ($_[0]);
		727	};
		728	};
		729
		730	$grp
		731	}
		732
		733	=item aio_copy $srcpath, $dstpath, $callback->($status)
		734
		735	Try to copy the I<file> (directories not supported as either source or
		736	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		737	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		738
		739	This is a composite request that creates the destination file with
		740	mode 0200 and copies the contents of the source file into it using
		741	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		742	uid/gid, in that order.
		743
		744	If an error occurs, the partial destination file will be unlinked, if
		745	possible, except when setting atime, mtime, access mode and uid/gid, where
		746	errors are being ignored.
		747
		748	=cut
		749
		750	sub aio_copy($$;$) {
		751	my ($src, $dst, $cb) = @_;
		752
		753	my $pri = aioreq_pri;
		754	my $grp = aio_group $cb;
		755
		756	aioreq_pri $pri;
		757	add $grp aio_open $src, O_RDONLY, 0, sub {
		758	if (my $src_fh = $_[0]) {
		759	my @stat = stat $src_fh; # hmm, might block over nfs?
		760
		761	aioreq_pri $pri;
		762	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		763	if (my $dst_fh = $_[0]) {
		764	aioreq_pri $pri;
		765	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		766	if ($_[0] == $stat[7]) {
		767	$grp->result (0);
		768	close $src_fh;
		769
		770	my $ch = sub {
		771	aioreq_pri $pri;
		772	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		773	aioreq_pri $pri;
		774	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		775	aioreq_pri $pri;
		776	add $grp aio_close $dst_fh;
		777	}
		778	};
		779	};
		780
		781	aioreq_pri $pri;
		782	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		783	if ($_[0] < 0 && $! == ENOSYS) {
		784	aioreq_pri $pri;
		785	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		786	} else {
		787	$ch->();
		788	}
		789	};
		790	} else {
		791	$grp->result (-1);
		792	close $src_fh;
		793	close $dst_fh;
		794
		795	aioreq $pri;
		796	add $grp aio_unlink $dst;
		797	}
		798	};
		799	} else {
		800	$grp->result (-1);
		801	}
		802	},
		803
		804	} else {
		805	$grp->result (-1);
		806	}
		807	};
		808
		809	$grp
		810	}
		811
		812	=item aio_move $srcpath, $dstpath, $callback->($status)
		813
		814	Try to move the I<file> (directories not supported as either source or
		815	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		816	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		817
		818	This is a composite request that tries to rename(2) the file first; if
		819	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		820	that is successful, unlinks the C<$srcpath>.
		821
		822	=cut
		823
		824	sub aio_move($$;$) {
		825	my ($src, $dst, $cb) = @_;
		826
		827	my $pri = aioreq_pri;
		828	my $grp = aio_group $cb;
		829
		830	aioreq_pri $pri;
		831	add $grp aio_rename $src, $dst, sub {
		832	if ($_[0] && $! == EXDEV) {
		833	aioreq_pri $pri;
		834	add $grp aio_copy $src, $dst, sub {
		835	$grp->result ($_[0]);
		836
		837	if (!$_[0]) {
		838	aioreq_pri $pri;
		839	add $grp aio_unlink $src;
		840	}
		841	};
		842	} else {
		843	$grp->result ($_[0]);
		844	}
		845	};
		846
		847	$grp
		848	}
345		849
346	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	850	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
347		851
348	Scans a directory (similar to C<aio_readdir>) but additionally tries to	852	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	853	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	854	names, directories you can recurse into (directories), and ones you cannot
351	recurse into (everything else).	855	recurse into (everything else, including symlinks to directories).
352		856
353	C<aio_scandir> is a composite request that consists of many sub	857	C<aio_scandir> is a composite request that creates of many sub requests_
354	requests. C<$maxreq> specifies the maximum number of outstanding aio	858	C<$maxreq> specifies the maximum number of outstanding aio requests that
355	requests that this function generates. If it is C<< <= 0 >>, then a	859	this function generates. If it is C<< <= 0 >>, then a suitable default
356	suitable default will be chosen (currently 8).	860	will be chosen (currently 4).
357		861
358	On error, the callback is called without arguments, otherwise it receives	862	On error, the callback is called without arguments, otherwise it receives
359	two array-refs with path-relative entry names.	863	two array-refs with path-relative entry names.
360		864
361	Example:	865	Example:
…		…
368		872
369	Implementation notes.	873	Implementation notes.
370		874
371	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	875	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
372		876
		877	If readdir returns file type information, then this is used directly to
		878	find directories.
		879
373	After reading the directory, the modification time, size etc. of the	880	Otherwise, after reading the directory, the modification time, size etc.
374	directory before and after the readdir is checked, and if they match (and	881	of the directory before and after the readdir is checked, and if they
375	isn't the current time), the link count will be used to decide how many	882	match (and isn't the current time), the link count will be used to decide
376	entries are directories (if >= 2). Otherwise, no knowledge of the number	883	how many entries are directories (if >= 2). Otherwise, no knowledge of the
377	of subdirectories will be assumed.	884	number of subdirectories will be assumed.
378		885
379	Then entries will be sorted into likely directories (everything without	886	Then entries will be sorted into likely directories a non-initial dot
380	a non-initial dot currently) and likely non-directories (everything	887	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,	888	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	889	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	890	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	891	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	892	filesystems might detect the type of the entry without reading the inode
386	data (e.g. ext2fs filetype feature).	893	data (e.g. ext2fs filetype feature), even on systems that cannot return
		894	the filetype information on readdir.
387		895
388	If the known number of directories (link count - 2) has been reached, the	896	If the known number of directories (link count - 2) has been reached, the
389	rest of the entries is assumed to be non-directories.	897	rest of the entries is assumed to be non-directories.
390		898
391	This only works with certainty on POSIX (= UNIX) filesystems, which	899	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	903	as those tend to return 0 or 1 as link counts, which disables the
396	directory counting heuristic.	904	directory counting heuristic.
397		905
398	=cut	906	=cut
399		907
400	sub aio_scandir($$$) {	908	sub aio_scandir($$;$) {
401	my ($path, $maxreq, $cb) = @_;	909	my ($path, $maxreq, $cb) = @_;
402		910
		911	my $pri = aioreq_pri;
		912
403	my $grp = aio_group;	913	my $grp = aio_group $cb;
404		914
405	$maxreq = 8 if $maxreq <= 0;	915	$maxreq = 4 if $maxreq <= 0;
406		916
407	# stat once	917	# stat once
		918	aioreq_pri $pri;
408	add $grp aio_stat $path, sub {	919	add $grp aio_stat $path, sub {
409	return $cb->() if $_[0];	920	return $grp->result () if $_[0];
410	my $now = time;	921	my $now = time;
411	my $hash1 = join ":", (stat _)[0,1,3,7,9];	922	my $hash1 = join ":", (stat _)[0,1,3,7,9];
412		923
413	# read the directory entries	924	# read the directory entries
		925	aioreq_pri $pri;
414	add $grp aio_readdir $path, sub {	926	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
415	my $entries = shift	927	my $entries = shift
416	or return $cb->();	928	or return $grp->result ();
417		929
418	# stat the dir another time	930	# stat the dir another time
		931	aioreq_pri $pri;
419	add $grp aio_stat $path, sub {	932	add $grp aio_stat $path, sub {
420	my $hash2 = join ":", (stat _)[0,1,3,7,9];	933	my $hash2 = join ":", (stat _)[0,1,3,7,9];
421		934
422	my $ndirs;	935	my $ndirs;
423		936
424	# take the slow route if anything looks fishy	937	# take the slow route if anything looks fishy
425	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	938	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
426	$ndirs = -1;	939	$ndirs = -1;
427	} else {	940	} else {
428	# if nlink == 2, we are finished	941	# if nlink == 2, we are finished
429	# on non-posix-fs's, we rely on nlink < 2	942	# for non-posix-fs's, we rely on nlink < 2
430	$ndirs = (stat _)[3] - 2	943	$ndirs = (stat _)[3] - 2
431	or return $cb->([], $entries);	944	or return $grp->result ([], $entries);
432	}	945	}
433		946
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	@$entries];
440
441	my (@dirs, @nondirs);	947	my (@dirs, @nondirs);
442		948
443	my ($statcb, $schedcb);	949	my $statgrp = add $grp aio_group sub {
444	my $nreq = 0;	950	$grp->result (\@dirs, \@nondirs);
		951	};
445		952
446	$schedcb = sub {	953	limit $statgrp $maxreq;
447	if (@$entries) {	954	feed $statgrp sub {
448	if ($nreq < $maxreq) {	955	return unless @$entries;
449	my $ent = pop @$entries;	956	my $entry = shift @$entries;
		957
		958	aioreq_pri $pri;
		959	add $statgrp aio_stat "$path/$entry/.", sub {
		960	if ($_[0] < 0) {
		961	push @nondirs, $entry;
		962	} else {
		963	# need to check for real directory
		964	aioreq_pri $pri;
		965	add $statgrp aio_lstat "$path/$entry", sub {
		966	if (-d _) {
		967	push @dirs, $entry;
		968
		969	unless (--$ndirs) {
		970	push @nondirs, @$entries;
		971	feed $statgrp;
		972	}
		973	} else {
		974	push @nondirs, $entry;
		975	}
450	$nreq++;	976	}
451	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
452	}	977	}
453	} elsif (!$nreq) {
454	# finished
455	undef $statcb;
456	undef $schedcb;
457	$cb->(\@dirs, \@nondirs) if $cb;
458	undef $cb;
459	}	978	};
460	};	979	};
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	};	980	};
491	};	981	};
492	};	982	};
493		983
494	$grp	984	$grp
495	}	985	}
496		986
		987	=item aio_rmtree $path, $callback->($status)
		988
		989	Delete a directory tree starting (and including) C<$path>, return the
		990	status of the final C<rmdir> only. This is a composite request that
		991	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		992	everything else.
		993
		994	=cut
		995
		996	sub aio_rmtree;
		997	sub aio_rmtree($;$) {
		998	my ($path, $cb) = @_;
		999
		1000	my $pri = aioreq_pri;
		1001	my $grp = aio_group $cb;
		1002
		1003	aioreq_pri $pri;
		1004	add $grp aio_scandir $path, 0, sub {
		1005	my ($dirs, $nondirs) = @_;
		1006
		1007	my $dirgrp = aio_group sub {
		1008	add $grp aio_rmdir $path, sub {
		1009	$grp->result ($_[0]);
		1010	};
		1011	};
		1012
		1013	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1014	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1015
		1016	add $grp $dirgrp;
		1017	};
		1018
		1019	$grp
		1020	}
		1021
		1022	=item aio_sync $callback->($status)
		1023
		1024	Asynchronously call sync and call the callback when finished.
		1025
497	=item aio_fsync $fh, $callback->($status)	1026	=item aio_fsync $fh, $callback->($status)
498		1027
499	Asynchronously call fsync on the given filehandle and call the callback	1028	Asynchronously call fsync on the given filehandle and call the callback
500	with the fsync result code.	1029	with the fsync result code.
501		1030
…		…
505	callback with the fdatasync result code.	1034	callback with the fdatasync result code.
506		1035
507	If this call isn't available because your OS lacks it or it couldn't be	1036	If this call isn't available because your OS lacks it or it couldn't be
508	detected, it will be emulated by calling C<fsync> instead.	1037	detected, it will be emulated by calling C<fsync> instead.
509		1038
		1039	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1040
		1041	Sync the data portion of the file specified by C<$offset> and C<$length>
		1042	to disk (but NOT the metadata), by calling the Linux-specific
		1043	sync_file_range call. If sync_file_range is not available or it returns
		1044	ENOSYS, then fdatasync or fsync is being substituted.
		1045
		1046	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1047	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1048	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1049	manpage for details.
		1050
		1051	=item aio_pathsync $path, $callback->($status)
		1052
		1053	This request tries to open, fsync and close the given path. This is a
		1054	composite request intended to sync directories after directory operations
		1055	(E.g. rename). This might not work on all operating systems or have any
		1056	specific effect, but usually it makes sure that directory changes get
		1057	written to disc. It works for anything that can be opened for read-only,
		1058	not just directories.
		1059
		1060	Future versions of this function might fall back to other methods when
		1061	C<fsync> on the directory fails (such as calling C<sync>).
		1062
		1063	Passes C<0> when everything went ok, and C<-1> on error.
		1064
		1065	=cut
		1066
		1067	sub aio_pathsync($;$) {
		1068	my ($path, $cb) = @_;
		1069
		1070	my $pri = aioreq_pri;
		1071	my $grp = aio_group $cb;
		1072
		1073	aioreq_pri $pri;
		1074	add $grp aio_open $path, O_RDONLY, 0, sub {
		1075	my ($fh) = @_;
		1076	if ($fh) {
		1077	aioreq_pri $pri;
		1078	add $grp aio_fsync $fh, sub {
		1079	$grp->result ($_[0]);
		1080
		1081	aioreq_pri $pri;
		1082	add $grp aio_close $fh;
		1083	};
		1084	} else {
		1085	$grp->result (-1);
		1086	}
		1087	};
		1088
		1089	$grp
		1090	}
		1091
		1092	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1093
		1094	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1095	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1096	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1097	scalar must only be modified in-place while an aio operation is pending on
		1098	it).
		1099
		1100	It calls the C<msync> function of your OS, if available, with the memory
		1101	area starting at C<$offset> in the string and ending C<$length> bytes
		1102	later. If C<$length> is negative, counts from the end, and if C<$length>
		1103	is C<undef>, then it goes till the end of the string. The flags can be
		1104	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1105	C<IO::AIO::MS_SYNC>.
		1106
		1107	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1108
		1109	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1110	scalars.
		1111
		1112	It touches (reads or writes) all memory pages in the specified
		1113	range inside the scalar. All caveats and parameters are the same
		1114	as for C<aio_msync>, above, except for flags, which must be either
		1115	C<0> (which reads all pages and ensures they are instantiated) or
		1116	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1117	writing an octet from it, which dirties the page).
		1118
		1119	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1120
		1121	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1122	scalars.
		1123
		1124	It reads in all the pages of the underlying storage into memory (if any)
		1125	and locks them, so they are not getting swapped/paged out or removed.
		1126
		1127	If C<$length> is undefined, then the scalar will be locked till the end.
		1128
		1129	On systems that do not implement C<mlock>, this function returns C<-1>
		1130	and sets errno to C<ENOSYS>.
		1131
		1132	Note that the corresponding C<munlock> is synchronous and is
		1133	documented under L<MISCELLANEOUS FUNCTIONS>.
		1134
		1135	Example: open a file, mmap and mlock it - both will be undone when
		1136	C<$data> gets destroyed.
		1137
		1138	open my $fh, "<", $path or die "$path: $!";
		1139	my $data;
		1140	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1141	aio_mlock $data; # mlock in background
		1142
		1143	=item aio_mlockall $flags, $callback->($status)
		1144
		1145	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1146	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1147
		1148	On systems that do not implement C<mlockall>, this function returns C<-1>
		1149	and sets errno to C<ENOSYS>.
		1150
		1151	Note that the corresponding C<munlockall> is synchronous and is
		1152	documented under L<MISCELLANEOUS FUNCTIONS>.
		1153
		1154	Example: asynchronously lock all current and future pages into memory.
		1155
		1156	aio_mlockall IO::AIO::MCL_FUTURE;
		1157
510	=item aio_group $callback->()	1158	=item aio_group $callback->(...)
511
512	[EXPERIMENTAL]
513		1159
514	This is a very special aio request: Instead of doing something, it is a	1160	This is a very special aio request: Instead of doing something, it is a
515	container for other aio requests, which is useful if you want to bundle	1161	container for other aio requests, which is useful if you want to bundle
516	many requests into a single, composite, request.	1162	many requests into a single, composite, request with a definite callback
		1163	and the ability to cancel the whole request with its subrequests.
517		1164
518	Returns an object of class L<IO::AIO::GRP>. See its documentation below	1165	Returns an object of class L<IO::AIO::GRP>. See its documentation below
519	for more info.	1166	for more info.
520		1167
521	Example:	1168	Example:
…		…
527	add $grp	1174	add $grp
528	(aio_stat ...),	1175	(aio_stat ...),
529	(aio_stat ...),	1176	(aio_stat ...),
530	...;	1177	...;
531		1178
		1179	=item aio_nop $callback->()
		1180
		1181	This is a special request - it does nothing in itself and is only used for
		1182	side effects, such as when you want to add a dummy request to a group so
		1183	that finishing the requests in the group depends on executing the given
		1184	code.
		1185
		1186	While this request does nothing, it still goes through the execution
		1187	phase and still requires a worker thread. Thus, the callback will not
		1188	be executed immediately but only after other requests in the queue have
		1189	entered their execution phase. This can be used to measure request
		1190	latency.
		1191
532	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() *NOT EXPORTED*	1192	=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED*
533		1193
534	Mainly used for debugging and benchmarking, this aio request puts one of	1194	Mainly used for debugging and benchmarking, this aio request puts one of
535	the request workers to sleep for the given time.	1195	the request workers to sleep for the given time.
536		1196
537	While it is theoretically handy to have simple I/O scheduling requests	1197	While it is theoretically handy to have simple I/O scheduling requests
538	like sleep and file handle readable/writable, the overhead this creates	1198	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	1199	immense (it blocks a thread for a long time) so do not use this function
540	under artificial I/O pressure.	1200	except to put your application under artificial I/O pressure.
541		1201
542	=back	1202	=back
543		1203
544	=head2 IO::AIO::REQ CLASS	1204	=head2 IO::AIO::REQ CLASS
545		1205
546	All non-aggregate C<aio_*> functions return an object of this class when	1206	All non-aggregate C<aio_*> functions return an object of this class when
547	called in non-void context.	1207	called in non-void context.
548		1208
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	1209	=over 4
558		1210
559	=item $req->cancel	1211	=item cancel $req
560		1212
561	Cancels the request, if possible. Has the effect of skipping execution	1213	Cancels the request, if possible. Has the effect of skipping execution
562	when entering the B<execute> state and skipping calling the callback when	1214	when entering the B<execute> state and skipping calling the callback when
563	entering the the B<result> state, but will leave the request otherwise	1215	entering the the B<result> state, but will leave the request otherwise
564	untouched. That means that requests that currently execute will not be	1216	untouched (with the exception of readdir). That means that requests that
565	stopped and resources held by the request will not be freed prematurely.	1217	currently execute will not be stopped and resources held by the request
		1218	will not be freed prematurely.
		1219
		1220	=item cb $req $callback->(...)
		1221
		1222	Replace (or simply set) the callback registered to the request.
566		1223
567	=back	1224	=back
568		1225
569	=head2 IO::AIO::GRP CLASS	1226	=head2 IO::AIO::GRP CLASS
570		1227
…		…
585	You add requests by calling the C<add> method with one or more	1242	You add requests by calling the C<add> method with one or more
586	C<IO::AIO::REQ> objects:	1243	C<IO::AIO::REQ> objects:
587		1244
588	$grp->add (aio_unlink "...");	1245	$grp->add (aio_unlink "...");
589		1246
590	add $grp aio_stat "...", sub { ... };	1247	add $grp aio_stat "...", sub {
		1248	$_[0] or return $grp->result ("error");
		1249
		1250	# add another request dynamically, if first succeeded
		1251	add $grp aio_open "...", sub {
		1252	$grp->result ("ok");
		1253	};
		1254	};
591		1255
592	This makes it very easy to create composite requests (see the source of	1256	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.	1257	C<aio_move> for an application) that work and feel like simple requests.
594		1258
		1259	=over 4
		1260
595	The IO::AIO::GRP objects will be cleaned up during calls to	1261	=item * The IO::AIO::GRP objects will be cleaned up during calls to
596	C<IO::AIO::poll_cb>, just like any other request.	1262	C<IO::AIO::poll_cb>, just like any other request.
597		1263
598	They can be canceled like any other request. Canceling will cancel not	1264	=item * They can be canceled like any other request. Canceling will cancel not
599	just the request itself, but also all requests it contains.	1265	only the request itself, but also all requests it contains.
600		1266
601	They can also can also be added to other IO::AIO::GRP objects.	1267	=item * They can also can also be added to other IO::AIO::GRP objects.
		1268
		1269	=item * You must not add requests to a group from within the group callback (or
		1270	any later time).
		1271
		1272	=back
602		1273
603	Their lifetime, simplified, looks like this: when they are empty, they	1274	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	1275	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	1276	C<done> state, they will also finish. Otherwise they will continue to
606	exist.	1277	exist.
607		1278
608	That means after creating a group you have some time to add requests. And	1279	That means after creating a group you have some time to add requests
609	in the callbacks of those requests, you can add further requests to the	1280	(precisely before the callback has been invoked, which is only done within
610	group. And only when all those requests have finished will the the group	1281	the C<poll_cb>). And in the callbacks of those requests, you can add
611	itself finish.	1282	further requests to the group. And only when all those requests have
		1283	finished will the the group itself finish.
612		1284
613	=over 4	1285	=over 4
614		1286
		1287	=item add $grp ...
		1288
615	=item $grp->add (...)	1289	=item $grp->add (...)
616
617	=item add $grp ...
618		1290
619	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can	1291	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
620	be added, including other groups, as long as you do not create circular	1292	be added, including other groups, as long as you do not create circular
621	dependencies.	1293	dependencies.
622		1294
623	Returns all its arguments.	1295	Returns all its arguments.
624		1296
		1297	=item $grp->cancel_subs
		1298
		1299	Cancel all subrequests and clears any feeder, but not the group request
		1300	itself. Useful when you queued a lot of events but got a result early.
		1301
		1302	The group request will finish normally (you cannot add requests to the
		1303	group).
		1304
		1305	=item $grp->result (...)
		1306
		1307	Set the result value(s) that will be passed to the group callback when all
		1308	subrequests have finished and set the groups errno to the current value
		1309	of errno (just like calling C<errno> without an error number). By default,
		1310	no argument will be passed and errno is zero.
		1311
		1312	=item $grp->errno ([$errno])
		1313
		1314	Sets the group errno value to C<$errno>, or the current value of errno
		1315	when the argument is missing.
		1316
		1317	Every aio request has an associated errno value that is restored when
		1318	the callback is invoked. This method lets you change this value from its
		1319	default (0).
		1320
		1321	Calling C<result> will also set errno, so make sure you either set C<$!>
		1322	before the call to C<result>, or call c<errno> after it.
		1323
		1324	=item feed $grp $callback->($grp)
		1325
		1326	Sets a feeder/generator on this group: every group can have an attached
		1327	generator that generates requests if idle. The idea behind this is that,
		1328	although you could just queue as many requests as you want in a group,
		1329	this might starve other requests for a potentially long time. For example,
		1330	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
		1331	delaying any later requests for a long time.
		1332
		1333	To avoid this, and allow incremental generation of requests, you can
		1334	instead a group and set a feeder on it that generates those requests. The
		1335	feed callback will be called whenever there are few enough (see C<limit>,
		1336	below) requests active in the group itself and is expected to queue more
		1337	requests.
		1338
		1339	The feed callback can queue as many requests as it likes (i.e. C<add> does
		1340	not impose any limits).
		1341
		1342	If the feed does not queue more requests when called, it will be
		1343	automatically removed from the group.
		1344
		1345	If the feed limit is C<0> when this method is called, it will be set to
		1346	C<2> automatically.
		1347
		1348	Example:
		1349
		1350	# stat all files in @files, but only ever use four aio requests concurrently:
		1351
		1352	my $grp = aio_group sub { print "finished\n" };
		1353	limit $grp 4;
		1354	feed $grp sub {
		1355	my $file = pop @files
		1356	or return;
		1357
		1358	add $grp aio_stat $file, sub { ... };
		1359	};
		1360
		1361	=item limit $grp $num
		1362
		1363	Sets the feeder limit for the group: The feeder will be called whenever
		1364	the group contains less than this many requests.
		1365
		1366	Setting the limit to C<0> will pause the feeding process.
		1367
		1368	The default value for the limit is C<0>, but note that setting a feeder
		1369	automatically bumps it up to C<2>.
		1370
625	=back	1371	=back
626		1372
627	=head2 SUPPORT FUNCTIONS	1373	=head2 SUPPORT FUNCTIONS
628		1374
		1375	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1376
629	=over 4	1377	=over 4
630		1378
631	=item $fileno = IO::AIO::poll_fileno	1379	=item $fileno = IO::AIO::poll_fileno
632		1380
633	Return the I<request result pipe file descriptor>. This filehandle must be	1381	Return the I<request result pipe file descriptor>. This filehandle must be
634	polled for reading by some mechanism outside this module (e.g. Event or	1382	polled for reading by some mechanism outside this module (e.g. EV, Glib,
635	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1383	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
636	to call C<poll_cb> to check the results.	1384	you have to call C<poll_cb> to check the results.
637		1385
638	See C<poll_cb> for an example.	1386	See C<poll_cb> for an example.
639		1387
640	=item IO::AIO::poll_cb	1388	=item IO::AIO::poll_cb
641		1389
642	Process all outstanding events on the result pipe. You have to call this	1390	Process some outstanding events on the result pipe. You have to call this
643	regularly. Returns the number of events processed. Returns immediately	1391	regularly. Returns C<0> if all events could be processed, or C<-1> if it
644	when no events are outstanding.	1392	returned earlier for whatever reason. Returns immediately when no events
		1393	are outstanding. The amount of events processed depends on the settings of
		1394	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1395
		1396	If not all requests were processed for whatever reason, the filehandle
		1397	will still be ready when C<poll_cb> returns, so normally you don't have to
		1398	do anything special to have it called later.
645		1399
646	Example: Install an Event watcher that automatically calls	1400	Example: Install an Event watcher that automatically calls
647	IO::AIO::poll_cb with high priority:	1401	IO::AIO::poll_cb with high priority (more examples can be found in the
		1402	SYNOPSIS section, at the top of this document):
648		1403
649	Event->io (fd => IO::AIO::poll_fileno,	1404	Event->io (fd => IO::AIO::poll_fileno,
650	poll => 'r', async => 1,	1405	poll => 'r', async => 1,
651	cb => \&IO::AIO::poll_cb);	1406	cb => \&IO::AIO::poll_cb);
652		1407
653	=item IO::AIO::poll_wait	1408	=item IO::AIO::poll_wait
654		1409
		1410	If there are any outstanding requests and none of them in the result
655	Wait till the result filehandle becomes ready for reading (simply does a	1411	phase, wait till the result filehandle becomes ready for reading (simply
656	C<select> on the filehandle. This is useful if you want to synchronously wait	1412	does a C<select> on the filehandle. This is useful if you want to
657	for some requests to finish).	1413	synchronously wait for some requests to finish).
658		1414
659	See C<nreqs> for an example.	1415	See C<nreqs> for an example.
660		1416
		1417	=item IO::AIO::poll
		1418
		1419	Waits until some requests have been handled.
		1420
		1421	Returns the number of requests processed, but is otherwise strictly
		1422	equivalent to:
		1423
		1424	IO::AIO::poll_wait, IO::AIO::poll_cb
		1425
661	=item IO::AIO::nreqs	1426	=item IO::AIO::flush
662		1427
663	Returns the number of requests currently outstanding (i.e. for which their	1428	Wait till all outstanding AIO requests have been handled.
664	callback has not been invoked yet).
665		1429
666	Example: wait till there are no outstanding requests anymore:	1430	Strictly equivalent to:
667		1431
668	IO::AIO::poll_wait, IO::AIO::poll_cb	1432	IO::AIO::poll_wait, IO::AIO::poll_cb
669	while IO::AIO::nreqs;	1433	while IO::AIO::nreqs;
670		1434
671	=item IO::AIO::flush	1435	=item IO::AIO::max_poll_reqs $nreqs
672		1436
673	Wait till all outstanding AIO requests have been handled.	1437	=item IO::AIO::max_poll_time $seconds
674		1438
675	Strictly equivalent to:	1439	These set the maximum number of requests (default C<0>, meaning infinity)
		1440	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1441	the maximum amount of time (default C<0>, meaning infinity) spent in
		1442	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1443	of time C<poll_cb> is allowed to use).
676		1444
677	IO::AIO::poll_wait, IO::AIO::poll_cb	1445	Setting C<max_poll_time> to a non-zero value creates an overhead of one
678	while IO::AIO::nreqs;	1446	syscall per request processed, which is not normally a problem unless your
		1447	callbacks are really really fast or your OS is really really slow (I am
		1448	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
679		1449
680	=item IO::AIO::poll	1450	Setting these is useful if you want to ensure some level of
		1451	interactiveness when perl is not fast enough to process all requests in
		1452	time.
681		1453
682	Waits until some requests have been handled.	1454	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
683		1455
684	Strictly equivalent to:	1456	Example: Install an Event watcher that automatically calls
		1457	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1458	program get the CPU sometimes even under high AIO load.
685		1459
686	IO::AIO::poll_wait, IO::AIO::poll_cb	1460	# try not to spend much more than 0.1s in poll_cb
687	if IO::AIO::nreqs;	1461	IO::AIO::max_poll_time 0.1;
		1462
		1463	# use a low priority so other tasks have priority
		1464	Event->io (fd => IO::AIO::poll_fileno,
		1465	poll => 'r', nice => 1,
		1466	cb => &IO::AIO::poll_cb);
		1467
		1468	=back
		1469
		1470	=head3 CONTROLLING THE NUMBER OF THREADS
		1471
		1472	=over
688		1473
689	=item IO::AIO::min_parallel $nthreads	1474	=item IO::AIO::min_parallel $nthreads
690		1475
691	Set the minimum number of AIO threads to C<$nthreads>. The current default	1476	Set the minimum number of AIO threads to C<$nthreads>. The current
692	is C<4>, which means four asynchronous operations can be done at one time	1477	default is C<8>, which means eight asynchronous operations can execute
693	(the number of outstanding operations, however, is unlimited).	1478	concurrently at any one time (the number of outstanding requests,
		1479	however, is unlimited).
694		1480
695	IO::AIO starts threads only on demand, when an AIO request is queued and	1481	IO::AIO starts threads only on demand, when an AIO request is queued and
696	no free thread exists.	1482	no free thread exists. Please note that queueing up a hundred requests can
		1483	create demand for a hundred threads, even if it turns out that everything
		1484	is in the cache and could have been processed faster by a single thread.
697		1485
698	It is recommended to keep the number of threads low, as some Linux	1486	It is recommended to keep the number of threads relatively low, as some
699	kernel versions will scale negatively with the number of threads (higher	1487	Linux kernel versions will scale negatively with the number of threads
700	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1488	(higher parallelity => MUCH higher latency). With current Linux 2.6
701	threads should be fine.	1489	versions, 4-32 threads should be fine.
702		1490
703	Under most circumstances you don't need to call this function, as the	1491	Under most circumstances you don't need to call this function, as the
704	module selects a default that is suitable for low to moderate load.	1492	module selects a default that is suitable for low to moderate load.
705		1493
706	=item IO::AIO::max_parallel $nthreads	1494	=item IO::AIO::max_parallel $nthreads
…		…
715	This module automatically runs C<max_parallel 0> at program end, to ensure	1503	This module automatically runs C<max_parallel 0> at program end, to ensure
716	that all threads are killed and that there are no outstanding requests.	1504	that all threads are killed and that there are no outstanding requests.
717		1505
718	Under normal circumstances you don't need to call this function.	1506	Under normal circumstances you don't need to call this function.
719		1507
		1508	=item IO::AIO::max_idle $nthreads
		1509
		1510	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1511	threads that did not get a request to process within 10 seconds). That
		1512	means if a thread becomes idle while C<$nthreads> other threads are also
		1513	idle, it will free its resources and exit.
		1514
		1515	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1516	to allow for extremely high load situations, but want to free resources
		1517	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1518
		1519	The default is probably ok in most situations, especially if thread
		1520	creation is fast. If thread creation is very slow on your system you might
		1521	want to use larger values.
		1522
720	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1523	=item IO::AIO::max_outstanding $maxreqs
		1524
		1525	This is a very bad function to use in interactive programs because it
		1526	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1527	use an C<aio_group> together with a feed callback.
721		1528
722	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1529	Sets the maximum number of outstanding requests to C<$nreqs>. If you
723	try to queue up more than this number of requests, the caller will block until	1530	do queue up more than this number of requests, the next call to the
724	some requests have been handled.	1531	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1532	function will block until the limit is no longer exceeded.
725		1533
726	The default is very large, so normally there is no practical limit. If you	1534	The default value is very large, so there is no practical limit on the
727	queue up many requests in a loop it often improves speed if you set	1535	number of outstanding requests.
728	this to a relatively low number, such as C<100>.
729		1536
730	Under normal circumstances you don't need to call this function.	1537	You can still queue as many requests as you want. Therefore,
		1538	C<max_outstanding> is mainly useful in simple scripts (with low values) or
		1539	as a stop gap to shield against fatal memory overflow (with large values).
731		1540
732	=back	1541	=back
733		1542
		1543	=head3 STATISTICAL INFORMATION
		1544
		1545	=over
		1546
		1547	=item IO::AIO::nreqs
		1548
		1549	Returns the number of requests currently in the ready, execute or pending
		1550	states (i.e. for which their callback has not been invoked yet).
		1551
		1552	Example: wait till there are no outstanding requests anymore:
		1553
		1554	IO::AIO::poll_wait, IO::AIO::poll_cb
		1555	while IO::AIO::nreqs;
		1556
		1557	=item IO::AIO::nready
		1558
		1559	Returns the number of requests currently in the ready state (not yet
		1560	executed).
		1561
		1562	=item IO::AIO::npending
		1563
		1564	Returns the number of requests currently in the pending state (executed,
		1565	but not yet processed by poll_cb).
		1566
		1567	=back
		1568
		1569	=head3 MISCELLANEOUS FUNCTIONS
		1570
		1571	IO::AIO implements some functions that might be useful, but are not
		1572	asynchronous.
		1573
		1574	=over 4
		1575
		1576	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1577
		1578	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1579	but is blocking (this makes most sense if you know the input data is
		1580	likely cached already and the output filehandle is set to non-blocking
		1581	operations).
		1582
		1583	Returns the number of bytes copied, or C<-1> on error.
		1584
		1585	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1586
		1587	Simply calls the C<posix_fadvise> function (see its
		1588	manpage for details). The following advice constants are
		1589	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1590	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1591	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1592
		1593	On systems that do not implement C<posix_fadvise>, this function returns
		1594	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1595
		1596	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1597
		1598	Simply calls the C<posix_madvise> function (see its
		1599	manpage for details). The following advice constants are
		1600	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1601	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1602
		1603	On systems that do not implement C<posix_madvise>, this function returns
		1604	ENOSYS, otherwise the return value of C<posix_madvise>.
		1605
		1606	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1607
		1608	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1609	$scalar (see its manpage for details). The following protect
		1610	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1611	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1612
		1613	On systems that do not implement C<mprotect>, this function returns
		1614	ENOSYS, otherwise the return value of C<mprotect>.
		1615
		1616	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1617
		1618	Memory-maps a file (or anonymous memory range) and attaches it to the
		1619	given C<$scalar>, which will act like a string scalar.
		1620
		1621	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1622	change the string length, and most read-only operations such as copying it
		1623	or searching it with regexes and so on.
		1624
		1625	Anything else is unsafe and will, at best, result in memory leaks.
		1626
		1627	The memory map associated with the C<$scalar> is automatically removed
		1628	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1629	C<IO::AIO::munmap> functions are called.
		1630
		1631	This calls the C<mmap>(2) function internally. See your system's manual
		1632	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1633
		1634	The C<$length> must be larger than zero and smaller than the actual
		1635	filesize.
		1636
		1637	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1638	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1639
		1640	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1641	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1642	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1643	(which is set to C<MAP_ANON> if your system only provides this
		1644	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1645	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1646	C<IO::AIO::MAP_NONBLOCK>
		1647
		1648	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1649
		1650	C<$offset> is the offset from the start of the file - it generally must be
		1651	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1652
		1653	Example:
		1654
		1655	use Digest::MD5;
		1656	use IO::AIO;
		1657
		1658	open my $fh, "<verybigfile"
		1659	or die "$!";
		1660
		1661	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1662	or die "verybigfile: $!";
		1663
		1664	my $fast_md5 = md5 $data;
		1665
		1666	=item IO::AIO::munmap $scalar
		1667
		1668	Removes a previous mmap and undefines the C<$scalar>.
		1669
		1670	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1671
		1672	Calls the C<munlock> function, undoing the effects of a previous
		1673	C<aio_mlock> call (see its description for details).
		1674
		1675	=item IO::AIO::munlockall
		1676
		1677	Calls the C<munlockall> function.
		1678
		1679	On systems that do not implement C<munlockall>, this function returns
		1680	ENOSYS, otherwise the return value of C<munlockall>.
		1681
		1682	=back
		1683
734	=cut	1684	=cut
735		1685
736	# support function to convert a fd into a perl filehandle
737	sub _fd2fh {
738	return undef if $_[0] < 0;
739
740	# try to generate nice filehandles
741	my $sym = "IO::AIO::fd#$_[0]";
742	local *$sym;
743
744	open *$sym, "+<&=$_[0]" # usually works under any unix
745	or open *$sym, "<&=$_[0]" # cygwin needs this
746	or open *$sym, ">&=$_[0]" # or this
747	or return undef;
748
749	*$sym
750	}
751
752	min_parallel 4;	1686	min_parallel 8;
753		1687
754	END {	1688	END { flush }
755	max_parallel 0;
756	}
757		1689
758	1;	1690	1;
		1691
		1692	=head1 EVENT LOOP INTEGRATION
		1693
		1694	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1695	automatically into many event loops:
		1696
		1697	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1698	use AnyEvent::AIO;
		1699
		1700	You can also integrate IO::AIO manually into many event loops, here are
		1701	some examples of how to do this:
		1702
		1703	# EV integration
		1704	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1705
		1706	# Event integration
		1707	Event->io (fd => IO::AIO::poll_fileno,
		1708	poll => 'r',
		1709	cb => \&IO::AIO::poll_cb);
		1710
		1711	# Glib/Gtk2 integration
		1712	add_watch Glib::IO IO::AIO::poll_fileno,
		1713	in => sub { IO::AIO::poll_cb; 1 };
		1714
		1715	# Tk integration
		1716	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1717	readable => \&IO::AIO::poll_cb);
		1718
		1719	# Danga::Socket integration
		1720	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1721	\&IO::AIO::poll_cb);
759		1722
760	=head2 FORK BEHAVIOUR	1723	=head2 FORK BEHAVIOUR
761		1724
762	This module should do "the right thing" when the process using it forks:	1725	This module should do "the right thing" when the process using it forks:
763		1726
764	Before the fork, IO::AIO enters a quiescent state where no requests	1727	Before the fork, IO::AIO enters a quiescent state where no requests
765	can be added in other threads and no results will be processed. After	1728	can be added in other threads and no results will be processed. After
766	the fork the parent simply leaves the quiescent state and continues	1729	the fork the parent simply leaves the quiescent state and continues
767	request/result processing, while the child clears the request/result	1730	request/result processing, while the child frees the request/result queue
768	queue (so the requests started before the fork will only be handled in	1731	(so that the requests started before the fork will only be handled in the
769	the parent). Threads will be started on demand until the limit ste in the	1732	parent). Threads will be started on demand until the limit set in the
770	parent process has been reached again.	1733	parent process has been reached again.
771		1734
772	In short: the parent will, after a short pause, continue as if fork had	1735	In short: the parent will, after a short pause, continue as if fork had
773	not been called, while the child will act as if IO::AIO has not been used	1736	not been called, while the child will act as if IO::AIO has not been used
774	yet.	1737	yet.
775		1738
		1739	=head2 MEMORY USAGE
		1740
		1741	Per-request usage:
		1742
		1743	Each aio request uses - depending on your architecture - around 100-200
		1744	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1745	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1746	scalars and other data passed into aio requests will also be locked and
		1747	will consume memory till the request has entered the done state.
		1748
		1749	This is not awfully much, so queuing lots of requests is not usually a
		1750	problem.
		1751
		1752	Per-thread usage:
		1753
		1754	In the execution phase, some aio requests require more memory for
		1755	temporary buffers, and each thread requires a stack and other data
		1756	structures (usually around 16k-128k, depending on the OS).
		1757
		1758	=head1 KNOWN BUGS
		1759
		1760	Known bugs will be fixed in the next release.
		1761
776	=head1 SEE ALSO	1762	=head1 SEE ALSO
777		1763
778	L<Coro>, L<Linux::AIO> (obsolete).	1764	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1765	more natural syntax.
779		1766
780	=head1 AUTHOR	1767	=head1 AUTHOR
781		1768
782	Marc Lehmann <schmorp@schmorp.de>	1769	Marc Lehmann <schmorp@schmorp.de>
783	http://home.schmorp.de/	1770	http://home.schmorp.de/

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