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Revision 1.55 by root, Sun Oct 22 00:49:29 2006 UTC vs.
Revision 1.206 by root, Sun Jul 24 03:32:51 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
16	aio_read $fh, 30000, 1024, $buffer, 0, sub {	17	aio_read $fh, 30000, 1024, $buffer, 0, sub {
17	$_[0] > 0 or die "read error: $!";	18	$_[0] > 0 or die "read error: $!";
18	};	19	};
19		20
20	use IO::AIO 2; # version has aio objects	21	# version 2+ has request and group objects
		22	use IO::AIO 2;
21		23
		24	aioreq_pri 4; # give next request a very high priority
22	my $req = aio_unlink "/tmp/file", sub { };	25	my $req = aio_unlink "/tmp/file", sub { };
23	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
24		27
25	# AnyEvent	28	my $grp = aio_group sub { print "all stats done\n" };
26	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	29	add $grp aio_stat "..." for ...;
27	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
28
29	# Event
30	Event->io (fd => IO::AIO::poll_fileno,
31	poll => 'r',
32	cb => \&IO::AIO::poll_cb);
33
34	# Glib/Gtk2
35	add_watch Glib::IO IO::AIO::poll_fileno,
36	in => sub { IO::AIO::poll_cb; 1 };
37
38	# Tk
39	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
40	readable => \&IO::AIO::poll_cb);
41
42	# Danga::Socket
43	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
44	\&IO::AIO::poll_cb);
45
46		30
47	=head1 DESCRIPTION	31	=head1 DESCRIPTION
48		32
49	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
50	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>).
51		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
52	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
53	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
54	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
55	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
56	aio functions available on many operating systems. However, they are often	57	functions available on many operating systems. However, they are often
57	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
58	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
59	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.
60		62
61	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,
62	currently not reentrant, so use appropriate locking yourself, always call	64	it is currently not reentrant in any way, so use appropriate locking
63	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
64	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
65		161
66	=cut	162	=cut
67		163
68	package IO::AIO;	164	package IO::AIO;
69		165
70	no warnings;	166	use Carp ();
71	use strict 'vars';	167
		168	use common::sense;
72		169
73	use base 'Exporter';	170	use base 'Exporter';
74		171
75	BEGIN {	172	BEGIN {
76	our $VERSION = '2.0';	173	our $VERSION = '4.0';
77		174
78	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
79	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
80	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
		178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate
		179	aio_pathsync aio_readahead
		180	aio_rename aio_link aio_move aio_copy aio_group
		181	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		182	aio_chmod aio_utime aio_truncate
		183	aio_msync aio_mtouch aio_mlock aio_mlockall
81	aio_group);	184	aio_statvfs);
82	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	185
		186	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		187	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		188	min_parallel max_parallel max_idle idle_timeout
		189	nreqs nready npending nthreads
		190	max_poll_time max_poll_reqs
		191	sendfile fadvise madvise
		192	mmap munmap munlock munlockall);
		193
		194	push @AIO_REQ, qw(aio_busy); # not exported
83		195
84	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	196	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
85		197
86	require XSLoader;	198	require XSLoader;
87	XSLoader::load ("IO::AIO", $VERSION);	199	XSLoader::load ("IO::AIO", $VERSION);
88	}	200	}
89		201
90	=head1 FUNCTIONS	202	=head1 FUNCTIONS
91		203
		204	=head2 QUICK OVERVIEW
		205
		206	This section simply lists the prototypes of the most important functions
		207	for quick reference. See the following sections for function-by-function
		208	documentation.
		209
		210	aio_open $pathname, $flags, $mode, $callback->($fh)
		211	aio_close $fh, $callback->($status)
		212	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		213	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		214	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		215	aio_readahead $fh,$offset,$length, $callback->($retval)
		216	aio_stat $fh_or_path, $callback->($status)
		217	aio_lstat $fh, $callback->($status)
		218	aio_statvfs $fh_or_path, $callback->($statvfs)
		219	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		220	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		221	aio_truncate $fh_or_path, $offset, $callback->($status)
		222	aio_chmod $fh_or_path, $mode, $callback->($status)
		223	aio_unlink $pathname, $callback->($status)
		224	aio_mknod $path, $mode, $dev, $callback->($status)
		225	aio_link $srcpath, $dstpath, $callback->($status)
		226	aio_symlink $srcpath, $dstpath, $callback->($status)
		227	aio_readlink $path, $callback->($link)
		228	aio_realpath $path, $callback->($link)
		229	aio_rename $srcpath, $dstpath, $callback->($status)
		230	aio_mkdir $pathname, $mode, $callback->($status)
		231	aio_rmdir $pathname, $callback->($status)
		232	aio_readdir $pathname, $callback->($entries)
		233	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		234	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		235	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		236	aio_load $path, $data, $callback->($status)
		237	aio_copy $srcpath, $dstpath, $callback->($status)
		238	aio_move $srcpath, $dstpath, $callback->($status)
		239	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		240	aio_rmtree $path, $callback->($status)
		241	aio_sync $callback->($status)
		242	aio_syncfs $fh, $callback->($status)
		243	aio_fsync $fh, $callback->($status)
		244	aio_fdatasync $fh, $callback->($status)
		245	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		246	aio_pathsync $path, $callback->($status)
		247	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		248	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		249	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		250	aio_mlockall $flags, $callback->($status)
		251	aio_group $callback->(...)
		252	aio_nop $callback->()
		253
		254	$prev_pri = aioreq_pri [$pri]
		255	aioreq_nice $pri_adjust
		256
		257	IO::AIO::poll_wait
		258	IO::AIO::poll_cb
		259	IO::AIO::poll
		260	IO::AIO::flush
		261	IO::AIO::max_poll_reqs $nreqs
		262	IO::AIO::max_poll_time $seconds
		263	IO::AIO::min_parallel $nthreads
		264	IO::AIO::max_parallel $nthreads
		265	IO::AIO::max_idle $nthreads
		266	IO::AIO::idle_timeout $seconds
		267	IO::AIO::max_outstanding $maxreqs
		268	IO::AIO::nreqs
		269	IO::AIO::nready
		270	IO::AIO::npending
		271
		272	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		273	IO::AIO::fadvise $fh, $offset, $len, $advice
		274	IO::AIO::madvise $scalar, $offset, $length, $advice
		275	IO::AIO::mprotect $scalar, $offset, $length, $protect
		276	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		277	IO::AIO::munlockall
		278
92	=head2 AIO FUNCTIONS	279	=head2 AIO REQUEST FUNCTIONS
93		280
94	All the C<aio_*> calls are more or less thin wrappers around the syscall	281	All the C<aio_*> calls are more or less thin wrappers around the syscall
95	with the same name (sans C<aio_>). The arguments are similar or identical,	282	with the same name (sans C<aio_>). The arguments are similar or identical,
96	and they all accept an additional (and optional) C<$callback> argument	283	and they all accept an additional (and optional) C<$callback> argument
97	which must be a code reference. This code reference will get called with	284	which must be a code reference. This code reference will get called with
98	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	285	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
99	perl, which usually delivers "false") as it's sole argument when the given	286	perl, which usually delivers "false") as its sole argument after the given
100	syscall has been executed asynchronously.	287	syscall has been executed asynchronously.
101		288
102	All functions expecting a filehandle keep a copy of the filehandle	289	All functions expecting a filehandle keep a copy of the filehandle
103	internally until the request has finished.	290	internally until the request has finished.
104		291
105	All requests return objects of type L<IO::AIO::REQ> that allow further	292	All functions return request objects of type L<IO::AIO::REQ> that allow
106	manipulation of those requests while they are in-flight.	293	further manipulation of those requests while they are in-flight.
107		294
108	The pathnames you pass to these routines I<must> be absolute and	295	The pathnames you pass to these routines I<must> be absolute and
109	encoded in byte form. The reason for the former is that at the time the	296	encoded as octets. The reason for the former is that at the time the
110	request is being executed, the current working directory could have	297	request is being executed, the current working directory could have
111	changed. Alternatively, you can make sure that you never change the	298	changed. Alternatively, you can make sure that you never change the
112	current working directory.	299	current working directory anywhere in the program and then use relative
		300	paths.
113		301
114	To encode pathnames to byte form, either make sure you either: a)	302	To encode pathnames as octets, either make sure you either: a) always pass
115	always pass in filenames you got from outside (command line, readdir	303	in filenames you got from outside (command line, readdir etc.) without
116	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	304	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
117	your pathnames to the locale (or other) encoding in effect in the user	305	your pathnames to the locale (or other) encoding in effect in the user
118	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	306	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
119	use something else.	307	use something else to ensure your scalar has the correct contents.
		308
		309	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		310	handles correctly whether it is set or not.
120		311
121	=over 4	312	=over 4
		313
		314	=item $prev_pri = aioreq_pri [$pri]
		315
		316	Returns the priority value that would be used for the next request and, if
		317	C<$pri> is given, sets the priority for the next aio request.
		318
		319	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		320	and C<4>, respectively. Requests with higher priority will be serviced
		321	first.
		322
		323	The priority will be reset to C<0> after each call to one of the C<aio_*>
		324	functions.
		325
		326	Example: open a file with low priority, then read something from it with
		327	higher priority so the read request is serviced before other low priority
		328	open requests (potentially spamming the cache):
		329
		330	aioreq_pri -3;
		331	aio_open ..., sub {
		332	return unless $_[0];
		333
		334	aioreq_pri -2;
		335	aio_read $_[0], ..., sub {
		336	...
		337	};
		338	};
		339
		340
		341	=item aioreq_nice $pri_adjust
		342
		343	Similar to C<aioreq_pri>, but subtracts the given value from the current
		344	priority, so the effect is cumulative.
		345
122		346
123	=item aio_open $pathname, $flags, $mode, $callback->($fh)	347	=item aio_open $pathname, $flags, $mode, $callback->($fh)
124		348
125	Asynchronously open or create a file and call the callback with a newly	349	Asynchronously open or create a file and call the callback with a newly
126	created filehandle for the file.	350	created filehandle for the file.
…		…
132	list. They are the same as used by C<sysopen>.	356	list. They are the same as used by C<sysopen>.
133		357
134	Likewise, C<$mode> specifies the mode of the newly created file, if it	358	Likewise, C<$mode> specifies the mode of the newly created file, if it
135	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	359	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
136	except that it is mandatory (i.e. use C<0> if you don't create new files,	360	except that it is mandatory (i.e. use C<0> if you don't create new files,
137	and C<0666> or C<0777> if you do).	361	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		362	by the umask in effect then the request is being executed, so better never
		363	change the umask.
138		364
139	Example:	365	Example:
140		366
141	aio_open "/etc/passwd", O_RDONLY, 0, sub {	367	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
142	if ($_[0]) {	368	if ($_[0]) {
143	print "open successful, fh is $_[0]\n";	369	print "open successful, fh is $_[0]\n";
144	...	370	...
145	} else {	371	} else {
146	die "open failed: $!\n";	372	die "open failed: $!\n";
147	}	373	}
148	};	374	};
149		375
		376	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		377	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		378	following POSIX and non-POSIX constants are available (missing ones on
		379	your system are, as usual, C<0>):
		380
		381	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		382	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		383	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		384
		385
150	=item aio_close $fh, $callback->($status)	386	=item aio_close $fh, $callback->($status)
151		387
152	Asynchronously close a file and call the callback with the result	388	Asynchronously close a file and call the callback with the result
153	code. I<WARNING:> although accepted, you should not pass in a perl	389	code.
154	filehandle here, as perl will likely close the file descriptor another
155	time when the filehandle is destroyed. Normally, you can safely call perls
156	C<close> or just let filehandles go out of scope.
157		390
158	This is supposed to be a bug in the API, so that might change. It's	391	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
159	therefore best to avoid this function.	392	closing the file descriptor associated with the filehandle itself.
		393
		394	Therefore, C<aio_close> will not close the filehandle - instead it will
		395	use dup2 to overwrite the file descriptor with the write-end of a pipe
		396	(the pipe fd will be created on demand and will be cached).
		397
		398	Or in other words: the file descriptor will be closed, but it will not be
		399	free for reuse until the perl filehandle is closed.
		400
		401	=cut
160		402
161	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	403	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
162		404
163	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	405	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
164		406
165	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	407	Reads or writes C<$length> bytes from or to the specified C<$fh> and
166	into the scalar given by C<data> and offset C<dataoffset> and calls the	408	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
167	callback without the actual number of bytes read (or -1 on error, just	409	and calls the callback without the actual number of bytes read (or -1 on
168	like the syscall).	410	error, just like the syscall).
		411
		412	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		413	offset plus the actual number of bytes read.
		414
		415	If C<$offset> is undefined, then the current file descriptor offset will
		416	be used (and updated), otherwise the file descriptor offset will not be
		417	changed by these calls.
		418
		419	If C<$length> is undefined in C<aio_write>, use the remaining length of
		420	C<$data>.
		421
		422	If C<$dataoffset> is less than zero, it will be counted from the end of
		423	C<$data>.
169		424
170	The C<$data> scalar I<MUST NOT> be modified in any way while the request	425	The C<$data> scalar I<MUST NOT> be modified in any way while the request
171	is outstanding. Modifying it can result in segfaults or WW3 (if the	426	is outstanding. Modifying it can result in segfaults or World War III (if
172	necessary/optional hardware is installed).	427	the necessary/optional hardware is installed).
173		428
174	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	429	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
175	offset C<0> within the scalar:	430	offset C<0> within the scalar:
176		431
177	aio_read $fh, 7, 15, $buffer, 0, sub {	432	aio_read $fh, 7, 15, $buffer, 0, sub {
178	$_[0] > 0 or die "read error: $!";	433	$_[0] > 0 or die "read error: $!";
179	print "read $_[0] bytes: <$buffer>\n";	434	print "read $_[0] bytes: <$buffer>\n";
180	};	435	};
181		436
182	=item aio_move $srcpath, $dstpath, $callback->($status)
183
184	Try to move the I<file> (directories not supported as either source or
185	destination) from C<$srcpath> to C<$dstpath> and call the callback with
186	the C<0> (error) or C<-1> ok.
187
188	This is a composite request that tries to rename(2) the file first. If
189	rename files with C<EXDEV>, it creates the destination file with mode 0200
190	and copies the contents of the source file into it using C<aio_sendfile>,
191	followed by restoring atime, mtime, access mode and uid/gid, in that
192	order, and unlinking the C<$srcpath>.
193
194	If an error occurs, the partial destination file will be unlinked, if
195	possible, except when setting atime, mtime, access mode and uid/gid, where
196	errors are being ignored.
197
198	=cut
199
200	sub aio_move($$$) {
201	my ($src, $dst, $cb) = @_;
202
203	my $grp = aio_group;
204
205	add $grp aio_rename $src, $dst, sub {
206	if ($_[0] && $! == EXDEV) {
207	add $grp aio_open $src, O_RDONLY, 0, sub {
208	if (my $src_fh = $_[0]) {
209	my @stat = stat $src_fh;
210
211	add $grp aio_open $dst, O_WRONLY, 0200, sub {
212	if (my $dst_fh = $_[0]) {
213	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
214	close $src_fh;
215
216	if ($_[0] == $stat[7]) {
217	utime $stat[8], $stat[9], $dst;
218	chmod $stat[2] & 07777, $dst_fh;
219	chown $stat[4], $stat[5], $dst_fh;
220	close $dst_fh;
221
222	add $grp aio_unlink $src, sub {
223	$cb->($_[0]);
224	};
225	} else {
226	my $errno = $!;
227	add $grp aio_unlink $dst, sub {
228	$! = $errno;
229	$cb->(-1);
230	};
231	}
232	};
233	} else {
234	$cb->(-1);
235	}
236	},
237
238	} else {
239	$cb->(-1);
240	}
241	};
242	} else {
243	$cb->($_[0]);
244	}
245	};
246
247	$grp
248	}
249		437
250	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	438	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
251		439
252	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	440	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
253	reading at byte offset C<$in_offset>, and starts writing at the current	441	reading at byte offset C<$in_offset>, and starts writing at the current
254	file offset of C<$out_fh>. Because of that, it is not safe to issue more	442	file offset of C<$out_fh>. Because of that, it is not safe to issue more
255	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	443	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
256	other.	444	other. The same C<$in_fh> works fine though, as this function does not
		445	move or use the file offset of C<$in_fh>.
257		446
		447	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		448	are written, and there is no way to find out how many more bytes have been
		449	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		450	number of bytes written to C<$out_fh>. Only if the result value equals
		451	C<$length> one can assume that C<$length> bytes have been read.
		452
		453	Unlike with other C<aio_> functions, it makes a lot of sense to use
		454	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		455	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		456	the socket I/O will be non-blocking. Note, however, that you can run
		457	into a trap where C<aio_sendfile> reads some data with readahead, then
		458	fails to write all data, and when the socket is ready the next time, the
		459	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		460	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		461	resource usage.
		462
258	This call tries to make use of a native C<sendfile> syscall to provide	463	This call tries to make use of a native C<sendfile>-like syscall to
259	zero-copy operation. For this to work, C<$out_fh> should refer to a	464	provide zero-copy operation. For this to work, C<$out_fh> should refer to
260	socket, and C<$in_fh> should refer to mmap'able file.	465	a socket, and C<$in_fh> should refer to an mmap'able file.
261		466
262	If the native sendfile call fails or is not implemented, it will be	467	If a native sendfile cannot be found or it fails with C<ENOSYS>,
263	emulated, so you can call C<aio_sendfile> on any type of filehandle	468	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		469	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
264	regardless of the limitations of the operating system.	470	type of filehandle regardless of the limitations of the operating system.
265		471
266	Please note, however, that C<aio_sendfile> can read more bytes from	472	As native sendfile syscalls (as practically any non-POSIX interface hacked
267	C<$in_fh> than are written, and there is no way to find out how many	473	together in a hurry to improve benchmark numbers) tend to be rather buggy
268	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	474	on many systems, this implementation tries to work around some known bugs
269	provides the number of bytes written to C<$out_fh>. Only if the result	475	in Linux and FreeBSD kernels (probably others, too), but that might fail,
270	value equals C<$length> one can assume that C<$length> bytes have been	476	so you really really should check the return value of C<aio_sendfile> -
271	read.	477	fewre bytes than expected might have been transferred.
		478
272		479
273	=item aio_readahead $fh,$offset,$length, $callback->($retval)	480	=item aio_readahead $fh,$offset,$length, $callback->($retval)
274		481
275	C<aio_readahead> populates the page cache with data from a file so that	482	C<aio_readahead> populates the page cache with data from a file so that
276	subsequent reads from that file will not block on disk I/O. The C<$offset>	483	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
282	file. The current file offset of the file is left unchanged.	489	file. The current file offset of the file is left unchanged.
283		490
284	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	491	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
285	emulated by simply reading the data, which would have a similar effect.	492	emulated by simply reading the data, which would have a similar effect.
286		493
		494
287	=item aio_stat $fh_or_path, $callback->($status)	495	=item aio_stat $fh_or_path, $callback->($status)
288		496
289	=item aio_lstat $fh, $callback->($status)	497	=item aio_lstat $fh, $callback->($status)
290		498
291	Works like perl's C<stat> or C<lstat> in void context. The callback will	499	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
296	for an explanation.	504	for an explanation.
297		505
298	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	506	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
299	error when stat'ing a large file, the results will be silently truncated	507	error when stat'ing a large file, the results will be silently truncated
300	unless perl itself is compiled with large file support.	508	unless perl itself is compiled with large file support.
		509
		510	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		511	following constants and functions (if not implemented, the constants will
		512	be C<0> and the functions will either C<croak> or fall back on traditional
		513	behaviour).
		514
		515	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		516	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		517	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
301		518
302	Example: Print the length of F</etc/passwd>:	519	Example: Print the length of F</etc/passwd>:
303		520
304	aio_stat "/etc/passwd", sub {	521	aio_stat "/etc/passwd", sub {
305	$_[0] and die "stat failed: $!";	522	$_[0] and die "stat failed: $!";
306	print "size is ", -s _, "\n";	523	print "size is ", -s _, "\n";
307	};	524	};
308		525
		526
		527	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		528
		529	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		530	whether a file handle or path was passed.
		531
		532	On success, the callback is passed a hash reference with the following
		533	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		534	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		535	is passed.
		536
		537	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		538	C<ST_NOSUID>.
		539
		540	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		541	their correct value when available, or to C<0> on systems that do
		542	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		543	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		544	C<ST_NODIRATIME> and C<ST_RELATIME>.
		545
		546	Example: stat C</wd> and dump out the data if successful.
		547
		548	aio_statvfs "/wd", sub {
		549	my $f = $_[0]
		550	or die "statvfs: $!";
		551
		552	use Data::Dumper;
		553	say Dumper $f;
		554	};
		555
		556	# result:
		557	{
		558	bsize => 1024,
		559	bfree => 4333064312,
		560	blocks => 10253828096,
		561	files => 2050765568,
		562	flag => 4096,
		563	favail => 2042092649,
		564	bavail => 4333064312,
		565	ffree => 2042092649,
		566	namemax => 255,
		567	frsize => 1024,
		568	fsid => 1810
		569	}
		570
		571
		572	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		573
		574	Works like perl's C<utime> function (including the special case of $atime
		575	and $mtime being undef). Fractional times are supported if the underlying
		576	syscalls support them.
		577
		578	When called with a pathname, uses utimes(2) if available, otherwise
		579	utime(2). If called on a file descriptor, uses futimes(2) if available,
		580	otherwise returns ENOSYS, so this is not portable.
		581
		582	Examples:
		583
		584	# set atime and mtime to current time (basically touch(1)):
		585	aio_utime "path", undef, undef;
		586	# set atime to current time and mtime to beginning of the epoch:
		587	aio_utime "path", time, undef; # undef==0
		588
		589
		590	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		591
		592	Works like perl's C<chown> function, except that C<undef> for either $uid
		593	or $gid is being interpreted as "do not change" (but -1 can also be used).
		594
		595	Examples:
		596
		597	# same as "chown root path" in the shell:
		598	aio_chown "path", 0, -1;
		599	# same as above:
		600	aio_chown "path", 0, undef;
		601
		602
		603	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		604
		605	Works like truncate(2) or ftruncate(2).
		606
		607
		608	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		609
		610	Works like perl's C<chmod> function.
		611
		612
309	=item aio_unlink $pathname, $callback->($status)	613	=item aio_unlink $pathname, $callback->($status)
310		614
311	Asynchronously unlink (delete) a file and call the callback with the	615	Asynchronously unlink (delete) a file and call the callback with the
312	result code.	616	result code.
313		617
		618
		619	=item aio_mknod $path, $mode, $dev, $callback->($status)
		620
		621	[EXPERIMENTAL]
		622
		623	Asynchronously create a device node (or fifo). See mknod(2).
		624
		625	The only (POSIX-) portable way of calling this function is:
		626
		627	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		628
		629	See C<aio_stat> for info about some potentially helpful extra constants
		630	and functions.
		631
314	=item aio_link $srcpath, $dstpath, $callback->($status)	632	=item aio_link $srcpath, $dstpath, $callback->($status)
315		633
316	Asynchronously create a new link to the existing object at C<$srcpath> at	634	Asynchronously create a new link to the existing object at C<$srcpath> at
317	the path C<$dstpath> and call the callback with the result code.	635	the path C<$dstpath> and call the callback with the result code.
318		636
		637
319	=item aio_symlink $srcpath, $dstpath, $callback->($status)	638	=item aio_symlink $srcpath, $dstpath, $callback->($status)
320		639
321	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	640	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
322	the path C<$dstpath> and call the callback with the result code.	641	the path C<$dstpath> and call the callback with the result code.
323		642
		643
		644	=item aio_readlink $path, $callback->($link)
		645
		646	Asynchronously read the symlink specified by C<$path> and pass it to
		647	the callback. If an error occurs, nothing or undef gets passed to the
		648	callback.
		649
		650
		651	=item aio_realpath $path, $callback->($path)
		652
		653	Asynchronously make the path absolute and resolve any symlinks in
		654	C<$path>. The resulting path only consists of directories (Same as
		655	L<Cwd::realpath>).
		656
		657	This request can be used to get the absolute path of the current working
		658	directory by passing it a path of F<.> (a single dot).
		659
		660
324	=item aio_rename $srcpath, $dstpath, $callback->($status)	661	=item aio_rename $srcpath, $dstpath, $callback->($status)
325		662
326	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	663	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
327	rename(2) and call the callback with the result code.	664	rename(2) and call the callback with the result code.
328		665
		666
		667	=item aio_mkdir $pathname, $mode, $callback->($status)
		668
		669	Asynchronously mkdir (create) a directory and call the callback with
		670	the result code. C<$mode> will be modified by the umask at the time the
		671	request is executed, so do not change your umask.
		672
		673
329	=item aio_rmdir $pathname, $callback->($status)	674	=item aio_rmdir $pathname, $callback->($status)
330		675
331	Asynchronously rmdir (delete) a directory and call the callback with the	676	Asynchronously rmdir (delete) a directory and call the callback with the
332	result code.	677	result code.
		678
333		679
334	=item aio_readdir $pathname, $callback->($entries)	680	=item aio_readdir $pathname, $callback->($entries)
335		681
336	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	682	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
337	directory (i.e. opendir + readdir + closedir). The entries will not be	683	directory (i.e. opendir + readdir + closedir). The entries will not be
338	sorted, and will B<NOT> include the C<.> and C<..> entries.	684	sorted, and will B<NOT> include the C<.> and C<..> entries.
339		685
340	The callback a single argument which is either C<undef> or an array-ref	686	The callback is passed a single argument which is either C<undef> or an
341	with the filenames.	687	array-ref with the filenames.
		688
		689
		690	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		691
		692	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		693	behaviour and output format. In case of an error, C<$entries> will be
		694	C<undef>.
		695
		696	The flags are a combination of the following constants, ORed together (the
		697	flags will also be passed to the callback, possibly modified):
		698
		699	=over 4
		700
		701	=item IO::AIO::READDIR_DENTS
		702
		703	When this flag is off, then the callback gets an arrayref consisting of
		704	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		705	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		706	entry in more detail.
		707
		708	C<$name> is the name of the entry.
		709
		710	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		711
		712	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		713	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		714	C<IO::AIO::DT_WHT>.
		715
		716	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		717	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		718	scalars are read-only: you can not modify them.
		719
		720	C<$inode> is the inode number (which might not be exact on systems with 64
		721	bit inode numbers and 32 bit perls). This field has unspecified content on
		722	systems that do not deliver the inode information.
		723
		724	=item IO::AIO::READDIR_DIRS_FIRST
		725
		726	When this flag is set, then the names will be returned in an order where
		727	likely directories come first, in optimal stat order. This is useful when
		728	you need to quickly find directories, or you want to find all directories
		729	while avoiding to stat() each entry.
		730
		731	If the system returns type information in readdir, then this is used
		732	to find directories directly. Otherwise, likely directories are names
		733	beginning with ".", or otherwise names with no dots, of which names with
		734	short names are tried first.
		735
		736	=item IO::AIO::READDIR_STAT_ORDER
		737
		738	When this flag is set, then the names will be returned in an order
		739	suitable for stat()'ing each one. That is, when you plan to stat()
		740	all files in the given directory, then the returned order will likely
		741	be fastest.
		742
		743	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		744	the likely dirs come first, resulting in a less optimal stat order.
		745
		746	=item IO::AIO::READDIR_FOUND_UNKNOWN
		747
		748	This flag should not be set when calling C<aio_readdirx>. Instead, it
		749	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		750	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		751	C<$type>'s are known, which can be used to speed up some algorithms.
		752
		753	=back
		754
		755
		756	=item aio_load $path, $data, $callback->($status)
		757
		758	This is a composite request that tries to fully load the given file into
		759	memory. Status is the same as with aio_read.
		760
		761	=cut
		762
		763	sub aio_load($$;$) {
		764	my ($path, undef, $cb) = @_;
		765	my $data = \$_[1];
		766
		767	my $pri = aioreq_pri;
		768	my $grp = aio_group $cb;
		769
		770	aioreq_pri $pri;
		771	add $grp aio_open $path, O_RDONLY, 0, sub {
		772	my $fh = shift
		773	or return $grp->result (-1);
		774
		775	aioreq_pri $pri;
		776	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		777	$grp->result ($_[0]);
		778	};
		779	};
		780
		781	$grp
		782	}
		783
		784	=item aio_copy $srcpath, $dstpath, $callback->($status)
		785
		786	Try to copy the I<file> (directories not supported as either source or
		787	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		788	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		789
		790	This is a composite request that creates the destination file with
		791	mode 0200 and copies the contents of the source file into it using
		792	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		793	uid/gid, in that order.
		794
		795	If an error occurs, the partial destination file will be unlinked, if
		796	possible, except when setting atime, mtime, access mode and uid/gid, where
		797	errors are being ignored.
		798
		799	=cut
		800
		801	sub aio_copy($$;$) {
		802	my ($src, $dst, $cb) = @_;
		803
		804	my $pri = aioreq_pri;
		805	my $grp = aio_group $cb;
		806
		807	aioreq_pri $pri;
		808	add $grp aio_open $src, O_RDONLY, 0, sub {
		809	if (my $src_fh = $_[0]) {
		810	my @stat = stat $src_fh; # hmm, might block over nfs?
		811
		812	aioreq_pri $pri;
		813	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		814	if (my $dst_fh = $_[0]) {
		815	aioreq_pri $pri;
		816	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		817	if ($_[0] == $stat[7]) {
		818	$grp->result (0);
		819	close $src_fh;
		820
		821	my $ch = sub {
		822	aioreq_pri $pri;
		823	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		824	aioreq_pri $pri;
		825	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		826	aioreq_pri $pri;
		827	add $grp aio_close $dst_fh;
		828	}
		829	};
		830	};
		831
		832	aioreq_pri $pri;
		833	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		834	if ($_[0] < 0 && $! == ENOSYS) {
		835	aioreq_pri $pri;
		836	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		837	} else {
		838	$ch->();
		839	}
		840	};
		841	} else {
		842	$grp->result (-1);
		843	close $src_fh;
		844	close $dst_fh;
		845
		846	aioreq $pri;
		847	add $grp aio_unlink $dst;
		848	}
		849	};
		850	} else {
		851	$grp->result (-1);
		852	}
		853	},
		854
		855	} else {
		856	$grp->result (-1);
		857	}
		858	};
		859
		860	$grp
		861	}
		862
		863	=item aio_move $srcpath, $dstpath, $callback->($status)
		864
		865	Try to move the I<file> (directories not supported as either source or
		866	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		867	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		868
		869	This is a composite request that tries to rename(2) the file first; if
		870	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		871	that is successful, unlinks the C<$srcpath>.
		872
		873	=cut
		874
		875	sub aio_move($$;$) {
		876	my ($src, $dst, $cb) = @_;
		877
		878	my $pri = aioreq_pri;
		879	my $grp = aio_group $cb;
		880
		881	aioreq_pri $pri;
		882	add $grp aio_rename $src, $dst, sub {
		883	if ($_[0] && $! == EXDEV) {
		884	aioreq_pri $pri;
		885	add $grp aio_copy $src, $dst, sub {
		886	$grp->result ($_[0]);
		887
		888	unless ($_[0]) {
		889	aioreq_pri $pri;
		890	add $grp aio_unlink $src;
		891	}
		892	};
		893	} else {
		894	$grp->result ($_[0]);
		895	}
		896	};
		897
		898	$grp
		899	}
342		900
343	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	901	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
344		902
345	Scans a directory (similar to C<aio_readdir>) but additionally tries to	903	Scans a directory (similar to C<aio_readdir>) but additionally tries to
346	separate the entries of directory C<$path> into two sets of names, ones	904	efficiently separate the entries of directory C<$path> into two sets of
347	you can recurse into (directories or links to them), and ones you cannot	905	names, directories you can recurse into (directories), and ones you cannot
348	recurse into (everything else).	906	recurse into (everything else, including symlinks to directories).
349		907
350	C<aio_scandir> is a composite request that consists of many sub	908	C<aio_scandir> is a composite request that creates of many sub requests_
351	requests. C<$maxreq> specifies the maximum number of outstanding aio	909	C<$maxreq> specifies the maximum number of outstanding aio requests that
352	requests that this function generates. If it is C<< <= 0 >>, then a	910	this function generates. If it is C<< <= 0 >>, then a suitable default
353	suitable default will be chosen (currently 8).	911	will be chosen (currently 4).
354		912
355	On error, the callback is called without arguments, otherwise it receives	913	On error, the callback is called without arguments, otherwise it receives
356	two array-refs with path-relative entry names.	914	two array-refs with path-relative entry names.
357		915
358	Example:	916	Example:
…		…
365		923
366	Implementation notes.	924	Implementation notes.
367		925
368	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	926	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
369		927
		928	If readdir returns file type information, then this is used directly to
		929	find directories.
		930
370	After reading the directory, the modification time, size etc. of the	931	Otherwise, after reading the directory, the modification time, size etc.
371	directory before and after the readdir is checked, and if they match (and	932	of the directory before and after the readdir is checked, and if they
372	isn't the current time), the link count will be used to decide how many	933	match (and isn't the current time), the link count will be used to decide
373	entries are directories (if >= 2). Otherwise, no knowledge of the number	934	how many entries are directories (if >= 2). Otherwise, no knowledge of the
374	of subdirectories will be assumed.	935	number of subdirectories will be assumed.
375		936
376	Then entries will be sorted into likely directories (everything without	937	Then entries will be sorted into likely directories a non-initial dot
377	a non-initial dot currently) and likely non-directories (everything	938	currently) and likely non-directories (see C<aio_readdirx>). Then every
378	else). Then every entry plus an appended C</.> will be C<stat>'ed,	939	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
379	likely directories first. If that succeeds, it assumes that the entry	940	in order of their inode numbers. If that succeeds, it assumes that the
380	is a directory or a symlink to directory (which will be checked	941	entry is a directory or a symlink to directory (which will be checked
381	seperately). This is often faster than stat'ing the entry itself because	942	seperately). This is often faster than stat'ing the entry itself because
382	filesystems might detect the type of the entry without reading the inode	943	filesystems might detect the type of the entry without reading the inode
383	data (e.g. ext2fs filetype feature).	944	data (e.g. ext2fs filetype feature), even on systems that cannot return
		945	the filetype information on readdir.
384		946
385	If the known number of directories (link count - 2) has been reached, the	947	If the known number of directories (link count - 2) has been reached, the
386	rest of the entries is assumed to be non-directories.	948	rest of the entries is assumed to be non-directories.
387		949
388	This only works with certainty on POSIX (= UNIX) filesystems, which	950	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
392	as those tend to return 0 or 1 as link counts, which disables the	954	as those tend to return 0 or 1 as link counts, which disables the
393	directory counting heuristic.	955	directory counting heuristic.
394		956
395	=cut	957	=cut
396		958
397	sub aio_scandir($$$) {	959	sub aio_scandir($$;$) {
398	my ($path, $maxreq, $cb) = @_;	960	my ($path, $maxreq, $cb) = @_;
399		961
		962	my $pri = aioreq_pri;
		963
400	my $grp = aio_group;	964	my $grp = aio_group $cb;
401		965
402	$maxreq = 8 if $maxreq <= 0;	966	$maxreq = 4 if $maxreq <= 0;
403		967
404	# stat once	968	# stat once
		969	aioreq_pri $pri;
405	add $grp aio_stat $path, sub {	970	add $grp aio_stat $path, sub {
406	return $cb->() if $_[0];	971	return $grp->result () if $_[0];
407	my $now = time;	972	my $now = time;
408	my $hash1 = join ":", (stat _)[0,1,3,7,9];	973	my $hash1 = join ":", (stat _)[0,1,3,7,9];
409		974
410	# read the directory entries	975	# read the directory entries
		976	aioreq_pri $pri;
411	add $grp aio_readdir $path, sub {	977	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
412	my $entries = shift	978	my $entries = shift
413	or return $cb->();	979	or return $grp->result ();
414		980
415	# stat the dir another time	981	# stat the dir another time
		982	aioreq_pri $pri;
416	add $grp aio_stat $path, sub {	983	add $grp aio_stat $path, sub {
417	my $hash2 = join ":", (stat _)[0,1,3,7,9];	984	my $hash2 = join ":", (stat _)[0,1,3,7,9];
418		985
419	my $ndirs;	986	my $ndirs;
420		987
421	# take the slow route if anything looks fishy	988	# take the slow route if anything looks fishy
422	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	989	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
423	$ndirs = -1;	990	$ndirs = -1;
424	} else {	991	} else {
425	# if nlink == 2, we are finished	992	# if nlink == 2, we are finished
426	# on non-posix-fs's, we rely on nlink < 2	993	# for non-posix-fs's, we rely on nlink < 2
427	$ndirs = (stat _)[3] - 2	994	$ndirs = (stat _)[3] - 2
428	or return $cb->([], $entries);	995	or return $grp->result ([], $entries);
429	}	996	}
430		997
431	# sort into likely dirs and likely nondirs
432	# dirs == files without ".", short entries first
433	$entries = [map $_->[0],
434	sort { $b->[1] cmp $a->[1] }
435	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
436	@$entries];
437
438	my (@dirs, @nondirs);	998	my (@dirs, @nondirs);
439		999
440	my ($statcb, $schedcb);	1000	my $statgrp = add $grp aio_group sub {
441	my $nreq = 0;	1001	$grp->result (\@dirs, \@nondirs);
		1002	};
442		1003
443	$schedcb = sub {	1004	limit $statgrp $maxreq;
444	if (@$entries) {	1005	feed $statgrp sub {
445	if ($nreq < $maxreq) {	1006	return unless @$entries;
446	my $ent = pop @$entries;	1007	my $entry = shift @$entries;
		1008
		1009	aioreq_pri $pri;
		1010	add $statgrp aio_stat "$path/$entry/.", sub {
		1011	if ($_[0] < 0) {
		1012	push @nondirs, $entry;
		1013	} else {
		1014	# need to check for real directory
		1015	aioreq_pri $pri;
		1016	add $statgrp aio_lstat "$path/$entry", sub {
		1017	if (-d _) {
		1018	push @dirs, $entry;
		1019
		1020	unless (--$ndirs) {
		1021	push @nondirs, @$entries;
		1022	feed $statgrp;
		1023	}
		1024	} else {
		1025	push @nondirs, $entry;
		1026	}
447	$nreq++;	1027	}
448	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
449	}	1028	}
450	} elsif (!$nreq) {
451	# finished
452	undef $statcb;
453	undef $schedcb;
454	$cb->(\@dirs, \@nondirs) if $cb;
455	undef $cb;
456	}	1029	};
457	};	1030	};
458	$statcb = sub {
459	my ($status, $entry) = @_;
460
461	if ($status < 0) {
462	$nreq--;
463	push @nondirs, $entry;
464	&$schedcb;
465	} else {
466	# need to check for real directory
467	add $grp aio_lstat "$path/$entry", sub {
468	$nreq--;
469
470	if (-d _) {
471	push @dirs, $entry;
472
473	if (!--$ndirs) {
474	push @nondirs, @$entries;
475	$entries = [];
476	}
477	} else {
478	push @nondirs, $entry;
479	}
480
481	&$schedcb;
482	}
483	}
484	};
485
486	&$schedcb while @$entries && $nreq < $maxreq;
487	};	1031	};
488	};	1032	};
489	};	1033	};
490		1034
491	$grp	1035	$grp
492	}	1036	}
493		1037
		1038	=item aio_rmtree $path, $callback->($status)
		1039
		1040	Delete a directory tree starting (and including) C<$path>, return the
		1041	status of the final C<rmdir> only. This is a composite request that
		1042	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		1043	everything else.
		1044
		1045	=cut
		1046
		1047	sub aio_rmtree;
		1048	sub aio_rmtree($;$) {
		1049	my ($path, $cb) = @_;
		1050
		1051	my $pri = aioreq_pri;
		1052	my $grp = aio_group $cb;
		1053
		1054	aioreq_pri $pri;
		1055	add $grp aio_scandir $path, 0, sub {
		1056	my ($dirs, $nondirs) = @_;
		1057
		1058	my $dirgrp = aio_group sub {
		1059	add $grp aio_rmdir $path, sub {
		1060	$grp->result ($_[0]);
		1061	};
		1062	};
		1063
		1064	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1065	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1066
		1067	add $grp $dirgrp;
		1068	};
		1069
		1070	$grp
		1071	}
		1072
		1073	=item aio_sync $callback->($status)
		1074
		1075	Asynchronously call sync and call the callback when finished.
		1076
494	=item aio_fsync $fh, $callback->($status)	1077	=item aio_fsync $fh, $callback->($status)
495		1078
496	Asynchronously call fsync on the given filehandle and call the callback	1079	Asynchronously call fsync on the given filehandle and call the callback
497	with the fsync result code.	1080	with the fsync result code.
498		1081
…		…
502	callback with the fdatasync result code.	1085	callback with the fdatasync result code.
503		1086
504	If this call isn't available because your OS lacks it or it couldn't be	1087	If this call isn't available because your OS lacks it or it couldn't be
505	detected, it will be emulated by calling C<fsync> instead.	1088	detected, it will be emulated by calling C<fsync> instead.
506		1089
		1090	=item aio_syncfs $fh, $callback->($status)
		1091
		1092	Asynchronously call the syncfs syscall to sync the filesystem associated
		1093	to the given filehandle and call the callback with the syncfs result
		1094	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1095	errno to C<ENOSYS> nevertheless.
		1096
		1097	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1098
		1099	Sync the data portion of the file specified by C<$offset> and C<$length>
		1100	to disk (but NOT the metadata), by calling the Linux-specific
		1101	sync_file_range call. If sync_file_range is not available or it returns
		1102	ENOSYS, then fdatasync or fsync is being substituted.
		1103
		1104	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1105	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1106	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1107	manpage for details.
		1108
		1109	=item aio_pathsync $path, $callback->($status)
		1110
		1111	This request tries to open, fsync and close the given path. This is a
		1112	composite request intended to sync directories after directory operations
		1113	(E.g. rename). This might not work on all operating systems or have any
		1114	specific effect, but usually it makes sure that directory changes get
		1115	written to disc. It works for anything that can be opened for read-only,
		1116	not just directories.
		1117
		1118	Future versions of this function might fall back to other methods when
		1119	C<fsync> on the directory fails (such as calling C<sync>).
		1120
		1121	Passes C<0> when everything went ok, and C<-1> on error.
		1122
		1123	=cut
		1124
		1125	sub aio_pathsync($;$) {
		1126	my ($path, $cb) = @_;
		1127
		1128	my $pri = aioreq_pri;
		1129	my $grp = aio_group $cb;
		1130
		1131	aioreq_pri $pri;
		1132	add $grp aio_open $path, O_RDONLY, 0, sub {
		1133	my ($fh) = @_;
		1134	if ($fh) {
		1135	aioreq_pri $pri;
		1136	add $grp aio_fsync $fh, sub {
		1137	$grp->result ($_[0]);
		1138
		1139	aioreq_pri $pri;
		1140	add $grp aio_close $fh;
		1141	};
		1142	} else {
		1143	$grp->result (-1);
		1144	}
		1145	};
		1146
		1147	$grp
		1148	}
		1149
		1150	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1151
		1152	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1153	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1154	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1155	scalar must only be modified in-place while an aio operation is pending on
		1156	it).
		1157
		1158	It calls the C<msync> function of your OS, if available, with the memory
		1159	area starting at C<$offset> in the string and ending C<$length> bytes
		1160	later. If C<$length> is negative, counts from the end, and if C<$length>
		1161	is C<undef>, then it goes till the end of the string. The flags can be
		1162	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1163	C<IO::AIO::MS_SYNC>.
		1164
		1165	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1166
		1167	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1168	scalars.
		1169
		1170	It touches (reads or writes) all memory pages in the specified
		1171	range inside the scalar. All caveats and parameters are the same
		1172	as for C<aio_msync>, above, except for flags, which must be either
		1173	C<0> (which reads all pages and ensures they are instantiated) or
		1174	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1175	writing an octet from it, which dirties the page).
		1176
		1177	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1178
		1179	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1180	scalars.
		1181
		1182	It reads in all the pages of the underlying storage into memory (if any)
		1183	and locks them, so they are not getting swapped/paged out or removed.
		1184
		1185	If C<$length> is undefined, then the scalar will be locked till the end.
		1186
		1187	On systems that do not implement C<mlock>, this function returns C<-1>
		1188	and sets errno to C<ENOSYS>.
		1189
		1190	Note that the corresponding C<munlock> is synchronous and is
		1191	documented under L<MISCELLANEOUS FUNCTIONS>.
		1192
		1193	Example: open a file, mmap and mlock it - both will be undone when
		1194	C<$data> gets destroyed.
		1195
		1196	open my $fh, "<", $path or die "$path: $!";
		1197	my $data;
		1198	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1199	aio_mlock $data; # mlock in background
		1200
		1201	=item aio_mlockall $flags, $callback->($status)
		1202
		1203	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1204	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1205
		1206	On systems that do not implement C<mlockall>, this function returns C<-1>
		1207	and sets errno to C<ENOSYS>.
		1208
		1209	Note that the corresponding C<munlockall> is synchronous and is
		1210	documented under L<MISCELLANEOUS FUNCTIONS>.
		1211
		1212	Example: asynchronously lock all current and future pages into memory.
		1213
		1214	aio_mlockall IO::AIO::MCL_FUTURE;
		1215
507	=item aio_group $callback->()	1216	=item aio_group $callback->(...)
508
509	[EXPERIMENTAL]
510		1217
511	This is a very special aio request: Instead of doing something, it is a	1218	This is a very special aio request: Instead of doing something, it is a
512	container for other aio requests, which is useful if you want to bundle	1219	container for other aio requests, which is useful if you want to bundle
513	many requests into a single, composite, request.	1220	many requests into a single, composite, request with a definite callback
		1221	and the ability to cancel the whole request with its subrequests.
514		1222
515	Returns an object of class L<IO::AIO::GRP>. See its documentation below	1223	Returns an object of class L<IO::AIO::GRP>. See its documentation below
516	for more info.	1224	for more info.
517		1225
518	Example:	1226	Example:
…		…
524	add $grp	1232	add $grp
525	(aio_stat ...),	1233	(aio_stat ...),
526	(aio_stat ...),	1234	(aio_stat ...),
527	...;	1235	...;
528		1236
		1237	=item aio_nop $callback->()
		1238
		1239	This is a special request - it does nothing in itself and is only used for
		1240	side effects, such as when you want to add a dummy request to a group so
		1241	that finishing the requests in the group depends on executing the given
		1242	code.
		1243
		1244	While this request does nothing, it still goes through the execution
		1245	phase and still requires a worker thread. Thus, the callback will not
		1246	be executed immediately but only after other requests in the queue have
		1247	entered their execution phase. This can be used to measure request
		1248	latency.
		1249
529	=item aio_sleep $fractional_seconds, $callback->() *NOT EXPORTED*	1250	=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED*
530		1251
531	Mainly used for debugging and benchmarking, this aio request puts one of	1252	Mainly used for debugging and benchmarking, this aio request puts one of
532	the request workers to sleep for the given time.	1253	the request workers to sleep for the given time.
533		1254
		1255	While it is theoretically handy to have simple I/O scheduling requests
		1256	like sleep and file handle readable/writable, the overhead this creates is
		1257	immense (it blocks a thread for a long time) so do not use this function
		1258	except to put your application under artificial I/O pressure.
		1259
534	=back	1260	=back
535		1261
536	=head2 IO::AIO::REQ CLASS	1262	=head2 IO::AIO::REQ CLASS
537		1263
538	All non-aggregate C<aio_*> functions return an object of this class when	1264	All non-aggregate C<aio_*> functions return an object of this class when
539	called in non-void context.	1265	called in non-void context.
540		1266
541	A request always moves through the following five states in its lifetime,
542	in order: B<ready> (request has been created, but has not been executed
543	yet), B<execute> (request is currently being executed), B<pending>
544	(request has been executed but callback has not been called yet),
545	B<result> (results are being processed synchronously, includes calling the
546	callback) and B<done> (request has reached the end of its lifetime and
547	holds no resources anymore).
548
549	=over 4	1267	=over 4
550		1268
551	=item $req->cancel	1269	=item cancel $req
552		1270
553	Cancels the request, if possible. Has the effect of skipping execution	1271	Cancels the request, if possible. Has the effect of skipping execution
554	when entering the B<execute> state and skipping calling the callback when	1272	when entering the B<execute> state and skipping calling the callback when
555	entering the the B<result> state, but will leave the request otherwise	1273	entering the the B<result> state, but will leave the request otherwise
556	untouched. That means that requests that currently execute will not be	1274	untouched (with the exception of readdir). That means that requests that
557	stopped and resources held by the request will not be freed prematurely.	1275	currently execute will not be stopped and resources held by the request
		1276	will not be freed prematurely.
		1277
		1278	=item cb $req $callback->(...)
		1279
		1280	Replace (or simply set) the callback registered to the request.
558		1281
559	=back	1282	=back
560		1283
561	=head2 IO::AIO::GRP CLASS	1284	=head2 IO::AIO::GRP CLASS
562		1285
…		…
577	You add requests by calling the C<add> method with one or more	1300	You add requests by calling the C<add> method with one or more
578	C<IO::AIO::REQ> objects:	1301	C<IO::AIO::REQ> objects:
579		1302
580	$grp->add (aio_unlink "...");	1303	$grp->add (aio_unlink "...");
581		1304
582	add $grp aio_stat "...", sub { ... };	1305	add $grp aio_stat "...", sub {
		1306	$_[0] or return $grp->result ("error");
		1307
		1308	# add another request dynamically, if first succeeded
		1309	add $grp aio_open "...", sub {
		1310	$grp->result ("ok");
		1311	};
		1312	};
583		1313
584	This makes it very easy to create composite requests (see the source of	1314	This makes it very easy to create composite requests (see the source of
585	C<aio_move> for an application) that work and feel like simple requests.	1315	C<aio_move> for an application) that work and feel like simple requests.
586		1316
		1317	=over 4
		1318
587	The IO::AIO::GRP objects will be cleaned up during calls to	1319	=item * The IO::AIO::GRP objects will be cleaned up during calls to
588	C<IO::AIO::poll_cb>, just like any other request.	1320	C<IO::AIO::poll_cb>, just like any other request.
589		1321
590	They can be canceled like any other request. Canceling will cancel not	1322	=item * They can be canceled like any other request. Canceling will cancel not
591	just the request itself, but also all requests it contains.	1323	only the request itself, but also all requests it contains.
592		1324
593	They can also can also be added to other IO::AIO::GRP objects.	1325	=item * They can also can also be added to other IO::AIO::GRP objects.
		1326
		1327	=item * You must not add requests to a group from within the group callback (or
		1328	any later time).
		1329
		1330	=back
594		1331
595	Their lifetime, simplified, looks like this: when they are empty, they	1332	Their lifetime, simplified, looks like this: when they are empty, they
596	will finish very quickly. If they contain only requests that are in the	1333	will finish very quickly. If they contain only requests that are in the
597	C<done> state, they will also finish. Otherwise they will continue to	1334	C<done> state, they will also finish. Otherwise they will continue to
598	exist.	1335	exist.
599		1336
		1337	That means after creating a group you have some time to add requests
		1338	(precisely before the callback has been invoked, which is only done within
		1339	the C<poll_cb>). And in the callbacks of those requests, you can add
		1340	further requests to the group. And only when all those requests have
		1341	finished will the the group itself finish.
		1342
600	=over 4	1343	=over 4
601		1344
		1345	=item add $grp ...
		1346
602	=item $grp->add (...)	1347	=item $grp->add (...)
603		1348
604	=item add $grp ...	1349	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		1350	be added, including other groups, as long as you do not create circular
		1351	dependencies.
605		1352
606	Add one or more	1353	Returns all its arguments.
607	Cancels the request, if possible. Has the effect of skipping execution	1354
608	when entering the B<execute> state and skipping calling the callback when	1355	=item $grp->cancel_subs
609	entering the the B<result> state, but will leave the request otherwise	1356
610	untouched. That means that requests that currently execute will not be	1357	Cancel all subrequests and clears any feeder, but not the group request
611	stopped and resources held by the request will not be freed prematurely.	1358	itself. Useful when you queued a lot of events but got a result early.
		1359
		1360	The group request will finish normally (you cannot add requests to the
		1361	group).
		1362
		1363	=item $grp->result (...)
		1364
		1365	Set the result value(s) that will be passed to the group callback when all
		1366	subrequests have finished and set the groups errno to the current value
		1367	of errno (just like calling C<errno> without an error number). By default,
		1368	no argument will be passed and errno is zero.
		1369
		1370	=item $grp->errno ([$errno])
		1371
		1372	Sets the group errno value to C<$errno>, or the current value of errno
		1373	when the argument is missing.
		1374
		1375	Every aio request has an associated errno value that is restored when
		1376	the callback is invoked. This method lets you change this value from its
		1377	default (0).
		1378
		1379	Calling C<result> will also set errno, so make sure you either set C<$!>
		1380	before the call to C<result>, or call c<errno> after it.
		1381
		1382	=item feed $grp $callback->($grp)
		1383
		1384	Sets a feeder/generator on this group: every group can have an attached
		1385	generator that generates requests if idle. The idea behind this is that,
		1386	although you could just queue as many requests as you want in a group,
		1387	this might starve other requests for a potentially long time. For example,
		1388	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
		1389	delaying any later requests for a long time.
		1390
		1391	To avoid this, and allow incremental generation of requests, you can
		1392	instead a group and set a feeder on it that generates those requests. The
		1393	feed callback will be called whenever there are few enough (see C<limit>,
		1394	below) requests active in the group itself and is expected to queue more
		1395	requests.
		1396
		1397	The feed callback can queue as many requests as it likes (i.e. C<add> does
		1398	not impose any limits).
		1399
		1400	If the feed does not queue more requests when called, it will be
		1401	automatically removed from the group.
		1402
		1403	If the feed limit is C<0> when this method is called, it will be set to
		1404	C<2> automatically.
		1405
		1406	Example:
		1407
		1408	# stat all files in @files, but only ever use four aio requests concurrently:
		1409
		1410	my $grp = aio_group sub { print "finished\n" };
		1411	limit $grp 4;
		1412	feed $grp sub {
		1413	my $file = pop @files
		1414	or return;
		1415
		1416	add $grp aio_stat $file, sub { ... };
		1417	};
		1418
		1419	=item limit $grp $num
		1420
		1421	Sets the feeder limit for the group: The feeder will be called whenever
		1422	the group contains less than this many requests.
		1423
		1424	Setting the limit to C<0> will pause the feeding process.
		1425
		1426	The default value for the limit is C<0>, but note that setting a feeder
		1427	automatically bumps it up to C<2>.
612		1428
613	=back	1429	=back
614		1430
615	=head2 SUPPORT FUNCTIONS	1431	=head2 SUPPORT FUNCTIONS
616		1432
		1433	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1434
617	=over 4	1435	=over 4
618		1436
619	=item $fileno = IO::AIO::poll_fileno	1437	=item $fileno = IO::AIO::poll_fileno
620		1438
621	Return the I<request result pipe file descriptor>. This filehandle must be	1439	Return the I<request result pipe file descriptor>. This filehandle must be
622	polled for reading by some mechanism outside this module (e.g. Event or	1440	polled for reading by some mechanism outside this module (e.g. EV, Glib,
623	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1441	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
624	to call C<poll_cb> to check the results.	1442	you have to call C<poll_cb> to check the results.
625		1443
626	See C<poll_cb> for an example.	1444	See C<poll_cb> for an example.
627		1445
628	=item IO::AIO::poll_cb	1446	=item IO::AIO::poll_cb
629		1447
630	Process all outstanding events on the result pipe. You have to call this	1448	Process some outstanding events on the result pipe. You have to call
631	regularly. Returns the number of events processed. Returns immediately	1449	this regularly. Returns C<0> if all events could be processed (or there
632	when no events are outstanding.	1450	were no events to process), or C<-1> if it returned earlier for whatever
		1451	reason. Returns immediately when no events are outstanding. The amount of
		1452	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1453	C<IO::AIO::max_poll_time>.
		1454
		1455	If not all requests were processed for whatever reason, the filehandle
		1456	will still be ready when C<poll_cb> returns, so normally you don't have to
		1457	do anything special to have it called later.
		1458
		1459	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1460	ready, it can be beneficial to call this function from loops which submit
		1461	a lot of requests, to make sure the results get processed when they become
		1462	available and not just when the loop is finished and the event loop takes
		1463	over again. This function returns very fast when there are no outstanding
		1464	requests.
633		1465
634	Example: Install an Event watcher that automatically calls	1466	Example: Install an Event watcher that automatically calls
635	IO::AIO::poll_cb with high priority:	1467	IO::AIO::poll_cb with high priority (more examples can be found in the
		1468	SYNOPSIS section, at the top of this document):
636		1469
637	Event->io (fd => IO::AIO::poll_fileno,	1470	Event->io (fd => IO::AIO::poll_fileno,
638	poll => 'r', async => 1,	1471	poll => 'r', async => 1,
639	cb => \&IO::AIO::poll_cb);	1472	cb => \&IO::AIO::poll_cb);
640		1473
641	=item IO::AIO::poll_wait	1474	=item IO::AIO::poll_wait
642		1475
		1476	If there are any outstanding requests and none of them in the result
643	Wait till the result filehandle becomes ready for reading (simply does a	1477	phase, wait till the result filehandle becomes ready for reading (simply
644	C<select> on the filehandle. This is useful if you want to synchronously wait	1478	does a C<select> on the filehandle. This is useful if you want to
645	for some requests to finish).	1479	synchronously wait for some requests to finish).
646		1480
647	See C<nreqs> for an example.	1481	See C<nreqs> for an example.
648		1482
		1483	=item IO::AIO::poll
		1484
		1485	Waits until some requests have been handled.
		1486
		1487	Returns the number of requests processed, but is otherwise strictly
		1488	equivalent to:
		1489
		1490	IO::AIO::poll_wait, IO::AIO::poll_cb
		1491
649	=item IO::AIO::nreqs	1492	=item IO::AIO::flush
650		1493
651	Returns the number of requests currently outstanding (i.e. for which their	1494	Wait till all outstanding AIO requests have been handled.
652	callback has not been invoked yet).
653		1495
654	Example: wait till there are no outstanding requests anymore:	1496	Strictly equivalent to:
655		1497
656	IO::AIO::poll_wait, IO::AIO::poll_cb	1498	IO::AIO::poll_wait, IO::AIO::poll_cb
657	while IO::AIO::nreqs;	1499	while IO::AIO::nreqs;
658		1500
659	=item IO::AIO::flush	1501	=item IO::AIO::max_poll_reqs $nreqs
660		1502
661	Wait till all outstanding AIO requests have been handled.	1503	=item IO::AIO::max_poll_time $seconds
662		1504
663	Strictly equivalent to:	1505	These set the maximum number of requests (default C<0>, meaning infinity)
		1506	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1507	the maximum amount of time (default C<0>, meaning infinity) spent in
		1508	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1509	of time C<poll_cb> is allowed to use).
664		1510
665	IO::AIO::poll_wait, IO::AIO::poll_cb	1511	Setting C<max_poll_time> to a non-zero value creates an overhead of one
666	while IO::AIO::nreqs;	1512	syscall per request processed, which is not normally a problem unless your
		1513	callbacks are really really fast or your OS is really really slow (I am
		1514	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
667		1515
668	=item IO::AIO::poll	1516	Setting these is useful if you want to ensure some level of
		1517	interactiveness when perl is not fast enough to process all requests in
		1518	time.
669		1519
670	Waits until some requests have been handled.	1520	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
671		1521
672	Strictly equivalent to:	1522	Example: Install an Event watcher that automatically calls
		1523	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1524	program get the CPU sometimes even under high AIO load.
673		1525
674	IO::AIO::poll_wait, IO::AIO::poll_cb	1526	# try not to spend much more than 0.1s in poll_cb
675	if IO::AIO::nreqs;	1527	IO::AIO::max_poll_time 0.1;
		1528
		1529	# use a low priority so other tasks have priority
		1530	Event->io (fd => IO::AIO::poll_fileno,
		1531	poll => 'r', nice => 1,
		1532	cb => &IO::AIO::poll_cb);
		1533
		1534	=back
		1535
		1536	=head3 CONTROLLING THE NUMBER OF THREADS
		1537
		1538	=over
676		1539
677	=item IO::AIO::min_parallel $nthreads	1540	=item IO::AIO::min_parallel $nthreads
678		1541
679	Set the minimum number of AIO threads to C<$nthreads>. The current default	1542	Set the minimum number of AIO threads to C<$nthreads>. The current
680	is C<4>, which means four asynchronous operations can be done at one time	1543	default is C<8>, which means eight asynchronous operations can execute
681	(the number of outstanding operations, however, is unlimited).	1544	concurrently at any one time (the number of outstanding requests,
		1545	however, is unlimited).
682		1546
683	IO::AIO starts threads only on demand, when an AIO request is queued and	1547	IO::AIO starts threads only on demand, when an AIO request is queued and
684	no free thread exists.	1548	no free thread exists. Please note that queueing up a hundred requests can
		1549	create demand for a hundred threads, even if it turns out that everything
		1550	is in the cache and could have been processed faster by a single thread.
685		1551
686	It is recommended to keep the number of threads low, as some Linux	1552	It is recommended to keep the number of threads relatively low, as some
687	kernel versions will scale negatively with the number of threads (higher	1553	Linux kernel versions will scale negatively with the number of threads
688	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1554	(higher parallelity => MUCH higher latency). With current Linux 2.6
689	threads should be fine.	1555	versions, 4-32 threads should be fine.
690		1556
691	Under most circumstances you don't need to call this function, as the	1557	Under most circumstances you don't need to call this function, as the
692	module selects a default that is suitable for low to moderate load.	1558	module selects a default that is suitable for low to moderate load.
693		1559
694	=item IO::AIO::max_parallel $nthreads	1560	=item IO::AIO::max_parallel $nthreads
…		…
703	This module automatically runs C<max_parallel 0> at program end, to ensure	1569	This module automatically runs C<max_parallel 0> at program end, to ensure
704	that all threads are killed and that there are no outstanding requests.	1570	that all threads are killed and that there are no outstanding requests.
705		1571
706	Under normal circumstances you don't need to call this function.	1572	Under normal circumstances you don't need to call this function.
707		1573
		1574	=item IO::AIO::max_idle $nthreads
		1575
		1576	Limit the number of threads (default: 4) that are allowed to idle
		1577	(i.e., threads that did not get a request to process within the idle
		1578	timeout (default: 10 seconds). That means if a thread becomes idle while
		1579	C<$nthreads> other threads are also idle, it will free its resources and
		1580	exit.
		1581
		1582	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1583	to allow for extremely high load situations, but want to free resources
		1584	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1585
		1586	The default is probably ok in most situations, especially if thread
		1587	creation is fast. If thread creation is very slow on your system you might
		1588	want to use larger values.
		1589
		1590	=item IO::AIO::idle_timeout $seconds
		1591
		1592	Sets the minimum idle timeout (default 10) after which worker threads are
		1593	allowed to exit. SEe C<IO::AIO::max_idle>.
		1594
708	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1595	=item IO::AIO::max_outstanding $maxreqs
709		1596
710	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1597	Sets the maximum number of outstanding requests to C<$nreqs>. If
711	try to queue up more than this number of requests, the caller will block until	1598	you do queue up more than this number of requests, the next call to
712	some requests have been handled.	1599	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1600	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1601	longer exceeded.
713		1602
714	The default is very large, so normally there is no practical limit. If you	1603	In other words, this setting does not enforce a queue limit, but can be
715	queue up many requests in a loop it often improves speed if you set	1604	used to make poll functions block if the limit is exceeded.
716	this to a relatively low number, such as C<100>.
717		1605
718	Under normal circumstances you don't need to call this function.	1606	This is a very bad function to use in interactive programs because it
		1607	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1608	use an C<aio_group> together with a feed callback.
		1609
		1610	It's main use is in scripts without an event loop - when you want to stat
		1611	a lot of files, you can write somehting like this:
		1612
		1613	IO::AIO::max_outstanding 32;
		1614
		1615	for my $path (...) {
		1616	aio_stat $path , ...;
		1617	IO::AIO::poll_cb;
		1618	}
		1619
		1620	IO::AIO::flush;
		1621
		1622	The call to C<poll_cb> inside the loop will normally return instantly, but
		1623	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1624	some requests have been handled. This keeps the loop from pushing a large
		1625	number of C<aio_stat> requests onto the queue.
		1626
		1627	The default value for C<max_outstanding> is very large, so there is no
		1628	practical limit on the number of outstanding requests.
719		1629
720	=back	1630	=back
721		1631
		1632	=head3 STATISTICAL INFORMATION
		1633
		1634	=over
		1635
		1636	=item IO::AIO::nreqs
		1637
		1638	Returns the number of requests currently in the ready, execute or pending
		1639	states (i.e. for which their callback has not been invoked yet).
		1640
		1641	Example: wait till there are no outstanding requests anymore:
		1642
		1643	IO::AIO::poll_wait, IO::AIO::poll_cb
		1644	while IO::AIO::nreqs;
		1645
		1646	=item IO::AIO::nready
		1647
		1648	Returns the number of requests currently in the ready state (not yet
		1649	executed).
		1650
		1651	=item IO::AIO::npending
		1652
		1653	Returns the number of requests currently in the pending state (executed,
		1654	but not yet processed by poll_cb).
		1655
		1656	=back
		1657
		1658	=head3 MISCELLANEOUS FUNCTIONS
		1659
		1660	IO::AIO implements some functions that might be useful, but are not
		1661	asynchronous.
		1662
		1663	=over 4
		1664
		1665	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1666
		1667	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1668	but is blocking (this makes most sense if you know the input data is
		1669	likely cached already and the output filehandle is set to non-blocking
		1670	operations).
		1671
		1672	Returns the number of bytes copied, or C<-1> on error.
		1673
		1674	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1675
		1676	Simply calls the C<posix_fadvise> function (see its
		1677	manpage for details). The following advice constants are
		1678	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1679	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1680	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1681
		1682	On systems that do not implement C<posix_fadvise>, this function returns
		1683	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1684
		1685	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1686
		1687	Simply calls the C<posix_madvise> function (see its
		1688	manpage for details). The following advice constants are
		1689	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1690	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1691
		1692	On systems that do not implement C<posix_madvise>, this function returns
		1693	ENOSYS, otherwise the return value of C<posix_madvise>.
		1694
		1695	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1696
		1697	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1698	$scalar (see its manpage for details). The following protect
		1699	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1700	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1701
		1702	On systems that do not implement C<mprotect>, this function returns
		1703	ENOSYS, otherwise the return value of C<mprotect>.
		1704
		1705	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1706
		1707	Memory-maps a file (or anonymous memory range) and attaches it to the
		1708	given C<$scalar>, which will act like a string scalar.
		1709
		1710	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1711	change the string length, and most read-only operations such as copying it
		1712	or searching it with regexes and so on.
		1713
		1714	Anything else is unsafe and will, at best, result in memory leaks.
		1715
		1716	The memory map associated with the C<$scalar> is automatically removed
		1717	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1718	C<IO::AIO::munmap> functions are called.
		1719
		1720	This calls the C<mmap>(2) function internally. See your system's manual
		1721	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1722
		1723	The C<$length> must be larger than zero and smaller than the actual
		1724	filesize.
		1725
		1726	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1727	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1728
		1729	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1730	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1731	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1732	(which is set to C<MAP_ANON> if your system only provides this
		1733	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1734	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1735	C<IO::AIO::MAP_NONBLOCK>
		1736
		1737	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1738
		1739	C<$offset> is the offset from the start of the file - it generally must be
		1740	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1741
		1742	Example:
		1743
		1744	use Digest::MD5;
		1745	use IO::AIO;
		1746
		1747	open my $fh, "<verybigfile"
		1748	or die "$!";
		1749
		1750	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1751	or die "verybigfile: $!";
		1752
		1753	my $fast_md5 = md5 $data;
		1754
		1755	=item IO::AIO::munmap $scalar
		1756
		1757	Removes a previous mmap and undefines the C<$scalar>.
		1758
		1759	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1760
		1761	Calls the C<munlock> function, undoing the effects of a previous
		1762	C<aio_mlock> call (see its description for details).
		1763
		1764	=item IO::AIO::munlockall
		1765
		1766	Calls the C<munlockall> function.
		1767
		1768	On systems that do not implement C<munlockall>, this function returns
		1769	ENOSYS, otherwise the return value of C<munlockall>.
		1770
		1771	=back
		1772
722	=cut	1773	=cut
723		1774
724	# support function to convert a fd into a perl filehandle
725	sub _fd2fh {
726	return undef if $_[0] < 0;
727
728	# try to generate nice filehandles
729	my $sym = "IO::AIO::fd#$_[0]";
730	local *$sym;
731
732	open *$sym, "+<&=$_[0]" # usually works under any unix
733	or open *$sym, "<&=$_[0]" # cygwin needs this
734	or open *$sym, ">&=$_[0]" # or this
735	or return undef;
736
737	*$sym
738	}
739
740	min_parallel 4;	1775	min_parallel 8;
741		1776
742	END {	1777	END { flush }
743	max_parallel 0;
744	}
745		1778
746	1;	1779	1;
747		1780
		1781	=head1 EVENT LOOP INTEGRATION
		1782
		1783	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1784	automatically into many event loops:
		1785
		1786	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1787	use AnyEvent::AIO;
		1788
		1789	You can also integrate IO::AIO manually into many event loops, here are
		1790	some examples of how to do this:
		1791
		1792	# EV integration
		1793	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1794
		1795	# Event integration
		1796	Event->io (fd => IO::AIO::poll_fileno,
		1797	poll => 'r',
		1798	cb => \&IO::AIO::poll_cb);
		1799
		1800	# Glib/Gtk2 integration
		1801	add_watch Glib::IO IO::AIO::poll_fileno,
		1802	in => sub { IO::AIO::poll_cb; 1 };
		1803
		1804	# Tk integration
		1805	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1806	readable => \&IO::AIO::poll_cb);
		1807
		1808	# Danga::Socket integration
		1809	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1810	\&IO::AIO::poll_cb);
		1811
748	=head2 FORK BEHAVIOUR	1812	=head2 FORK BEHAVIOUR
749		1813
750	This module should do "the right thing" when the process using it forks:	1814	Usage of pthreads in a program changes the semantics of fork
		1815	considerably. Specifically, only async-safe functions can be called after
		1816	fork. Perl doesn't know about this, so in general, you cannot call fork
		1817	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		1818	pthreads, so this applies, but many other extensions and (for inexplicable
		1819	reasons) perl itself often is linked against pthreads, so this limitation
		1820	applies to quite a lot of perls.
751		1821
752	Before the fork, IO::AIO enters a quiescent state where no requests	1822	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
753	can be added in other threads and no results will be processed. After	1823	only works in the process that loaded it. Forking is fully supported, but
754	the fork the parent simply leaves the quiescent state and continues	1824	using IO::AIO in the child is not.
755	request/result processing, while the child clears the request/result
756	queue (so the requests started before the fork will only be handled in
757	the parent). Threads will be started on demand until the limit ste in the
758	parent process has been reached again.
759		1825
760	In short: the parent will, after a short pause, continue as if fork had	1826	You might get around by not I<using> IO::AIO before (or after)
761	not been called, while the child will act as if IO::AIO has not been used	1827	forking. You could also try to call the L<IO::AIO::reinit> function in the
762	yet.	1828	child:
		1829
		1830	=over 4
		1831
		1832	=item IO::AIO::reinit
		1833
		1834	Abondons all current requests and I/O threads and simply reinitialises all
		1835	data structures. This is not an operation suppported by any standards, but
		1836	happens to work on GNU/Linux and some newer BSD systems.
		1837
		1838	The only reasonable use for this function is to call it after forking, if
		1839	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		1840	the process will result in undefined behaviour. Calling it at any time
		1841	will also result in any undefined (by POSIX) behaviour.
		1842
		1843	=back
		1844
		1845	=head2 MEMORY USAGE
		1846
		1847	Per-request usage:
		1848
		1849	Each aio request uses - depending on your architecture - around 100-200
		1850	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1851	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1852	scalars and other data passed into aio requests will also be locked and
		1853	will consume memory till the request has entered the done state.
		1854
		1855	This is not awfully much, so queuing lots of requests is not usually a
		1856	problem.
		1857
		1858	Per-thread usage:
		1859
		1860	In the execution phase, some aio requests require more memory for
		1861	temporary buffers, and each thread requires a stack and other data
		1862	structures (usually around 16k-128k, depending on the OS).
		1863
		1864	=head1 KNOWN BUGS
		1865
		1866	Known bugs will be fixed in the next release.
763		1867
764	=head1 SEE ALSO	1868	=head1 SEE ALSO
765		1869
766	L<Coro>, L<Linux::AIO> (obsolete).	1870	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1871	more natural syntax.
767		1872
768	=head1 AUTHOR	1873	=head1 AUTHOR
769		1874
770	Marc Lehmann <schmorp@schmorp.de>	1875	Marc Lehmann <schmorp@schmorp.de>
771	http://home.schmorp.de/	1876	http://home.schmorp.de/

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