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Revision 1.55 by root, Sun Oct 22 00:49:29 2006 UTC vs.
Revision 1.184 by root, Mon Nov 1 22:03:43 2010 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
10	my ($fh) = @_;	10	my $fh = shift
		11	or die "/etc/passwd: $!";
11	...	12	...
12	};	13	};
13		14
14	aio_unlink "/tmp/file", sub { };	15	aio_unlink "/tmp/file", sub { };
15		16
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 = '3.7';
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_sync aio_fsync
		178	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
		179	aio_rename aio_link aio_move aio_copy aio_group
		180	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		181	aio_chmod aio_utime aio_truncate
		182	aio_msync aio_mtouch aio_mlock aio_mlockall
81	aio_group);	183	aio_statvfs);
82	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	184
		185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		187	min_parallel max_parallel max_idle
		188	nreqs nready npending nthreads
		189	max_poll_time max_poll_reqs
		190	sendfile fadvise madvise
		191	mmap munmap munlock munlockall);
		192
		193	push @AIO_REQ, qw(aio_busy); # not exported
83		194
84	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	195	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
85		196
86	require XSLoader;	197	require XSLoader;
87	XSLoader::load ("IO::AIO", $VERSION);	198	XSLoader::load ("IO::AIO", $VERSION);
88	}	199	}
89		200
90	=head1 FUNCTIONS	201	=head1 FUNCTIONS
91		202
		203	=head2 QUICK OVERVIEW
		204
		205	This section simply lists the prototypes of the most important functions
		206	for quick reference. See the following sections for function-by-function
		207	documentation.
		208
		209	aio_open $pathname, $flags, $mode, $callback->($fh)
		210	aio_close $fh, $callback->($status)
		211	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		212	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		213	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		214	aio_readahead $fh,$offset,$length, $callback->($retval)
		215	aio_stat $fh_or_path, $callback->($status)
		216	aio_lstat $fh, $callback->($status)
		217	aio_statvfs $fh_or_path, $callback->($statvfs)
		218	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		219	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		220	aio_truncate $fh_or_path, $offset, $callback->($status)
		221	aio_chmod $fh_or_path, $mode, $callback->($status)
		222	aio_unlink $pathname, $callback->($status)
		223	aio_mknod $path, $mode, $dev, $callback->($status)
		224	aio_link $srcpath, $dstpath, $callback->($status)
		225	aio_symlink $srcpath, $dstpath, $callback->($status)
		226	aio_readlink $path, $callback->($link)
		227	aio_rename $srcpath, $dstpath, $callback->($status)
		228	aio_mkdir $pathname, $mode, $callback->($status)
		229	aio_rmdir $pathname, $callback->($status)
		230	aio_readdir $pathname, $callback->($entries)
		231	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		232	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		233	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		234	aio_load $path, $data, $callback->($status)
		235	aio_copy $srcpath, $dstpath, $callback->($status)
		236	aio_move $srcpath, $dstpath, $callback->($status)
		237	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		238	aio_rmtree $path, $callback->($status)
		239	aio_sync $callback->($status)
		240	aio_fsync $fh, $callback->($status)
		241	aio_fdatasync $fh, $callback->($status)
		242	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		243	aio_pathsync $path, $callback->($status)
		244	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		245	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		246	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		247	aio_mlockall $flags, $callback->($status)
		248	aio_group $callback->(...)
		249	aio_nop $callback->()
		250
		251	$prev_pri = aioreq_pri [$pri]
		252	aioreq_nice $pri_adjust
		253
		254	IO::AIO::poll_wait
		255	IO::AIO::poll_cb
		256	IO::AIO::poll
		257	IO::AIO::flush
		258	IO::AIO::max_poll_reqs $nreqs
		259	IO::AIO::max_poll_time $seconds
		260	IO::AIO::min_parallel $nthreads
		261	IO::AIO::max_parallel $nthreads
		262	IO::AIO::max_idle $nthreads
		263	IO::AIO::max_outstanding $maxreqs
		264	IO::AIO::nreqs
		265	IO::AIO::nready
		266	IO::AIO::npending
		267
		268	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		269	IO::AIO::fadvise $fh, $offset, $len, $advice
		270	IO::AIO::madvise $scalar, $offset, $length, $advice
		271	IO::AIO::mprotect $scalar, $offset, $length, $protect
		272	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		273	IO::AIO::munlockall
		274
92	=head2 AIO FUNCTIONS	275	=head2 AIO REQUEST FUNCTIONS
93		276
94	All the C<aio_*> calls are more or less thin wrappers around the syscall	277	All the C<aio_*> calls are more or less thin wrappers around the syscall
95	with the same name (sans C<aio_>). The arguments are similar or identical,	278	with the same name (sans C<aio_>). The arguments are similar or identical,
96	and they all accept an additional (and optional) C<$callback> argument	279	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	280	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	281	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	282	perl, which usually delivers "false") as its sole argument after the given
100	syscall has been executed asynchronously.	283	syscall has been executed asynchronously.
101		284
102	All functions expecting a filehandle keep a copy of the filehandle	285	All functions expecting a filehandle keep a copy of the filehandle
103	internally until the request has finished.	286	internally until the request has finished.
104		287
105	All requests return objects of type L<IO::AIO::REQ> that allow further	288	All functions return request objects of type L<IO::AIO::REQ> that allow
106	manipulation of those requests while they are in-flight.	289	further manipulation of those requests while they are in-flight.
107		290
108	The pathnames you pass to these routines I<must> be absolute and	291	The pathnames you pass to these routines I<must> be absolute and
109	encoded in byte form. The reason for the former is that at the time the	292	encoded as octets. The reason for the former is that at the time the
110	request is being executed, the current working directory could have	293	request is being executed, the current working directory could have
111	changed. Alternatively, you can make sure that you never change the	294	changed. Alternatively, you can make sure that you never change the
112	current working directory.	295	current working directory anywhere in the program and then use relative
		296	paths.
113		297
114	To encode pathnames to byte form, either make sure you either: a)	298	To encode pathnames as octets, either make sure you either: a) always pass
115	always pass in filenames you got from outside (command line, readdir	299	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	300	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	301	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)	302	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
119	use something else.	303	use something else to ensure your scalar has the correct contents.
		304
		305	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		306	handles correctly whether it is set or not.
120		307
121	=over 4	308	=over 4
		309
		310	=item $prev_pri = aioreq_pri [$pri]
		311
		312	Returns the priority value that would be used for the next request and, if
		313	C<$pri> is given, sets the priority for the next aio request.
		314
		315	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		316	and C<4>, respectively. Requests with higher priority will be serviced
		317	first.
		318
		319	The priority will be reset to C<0> after each call to one of the C<aio_*>
		320	functions.
		321
		322	Example: open a file with low priority, then read something from it with
		323	higher priority so the read request is serviced before other low priority
		324	open requests (potentially spamming the cache):
		325
		326	aioreq_pri -3;
		327	aio_open ..., sub {
		328	return unless $_[0];
		329
		330	aioreq_pri -2;
		331	aio_read $_[0], ..., sub {
		332	...
		333	};
		334	};
		335
		336
		337	=item aioreq_nice $pri_adjust
		338
		339	Similar to C<aioreq_pri>, but subtracts the given value from the current
		340	priority, so the effect is cumulative.
		341
122		342
123	=item aio_open $pathname, $flags, $mode, $callback->($fh)	343	=item aio_open $pathname, $flags, $mode, $callback->($fh)
124		344
125	Asynchronously open or create a file and call the callback with a newly	345	Asynchronously open or create a file and call the callback with a newly
126	created filehandle for the file.	346	created filehandle for the file.
…		…
132	list. They are the same as used by C<sysopen>.	352	list. They are the same as used by C<sysopen>.
133		353
134	Likewise, C<$mode> specifies the mode of the newly created file, if it	354	Likewise, C<$mode> specifies the mode of the newly created file, if it
135	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	355	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
136	except that it is mandatory (i.e. use C<0> if you don't create new files,	356	except that it is mandatory (i.e. use C<0> if you don't create new files,
137	and C<0666> or C<0777> if you do).	357	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		358	by the umask in effect then the request is being executed, so better never
		359	change the umask.
138		360
139	Example:	361	Example:
140		362
141	aio_open "/etc/passwd", O_RDONLY, 0, sub {	363	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
142	if ($_[0]) {	364	if ($_[0]) {
143	print "open successful, fh is $_[0]\n";	365	print "open successful, fh is $_[0]\n";
144	...	366	...
145	} else {	367	} else {
146	die "open failed: $!\n";	368	die "open failed: $!\n";
147	}	369	}
148	};	370	};
149		371
		372
150	=item aio_close $fh, $callback->($status)	373	=item aio_close $fh, $callback->($status)
151		374
152	Asynchronously close a file and call the callback with the result	375	Asynchronously close a file and call the callback with the result
153	code. I<WARNING:> although accepted, you should not pass in a perl	376	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		377
158	This is supposed to be a bug in the API, so that might change. It's	378	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
159	therefore best to avoid this function.	379	closing the file descriptor associated with the filehandle itself.
		380
		381	Therefore, C<aio_close> will not close the filehandle - instead it will
		382	use dup2 to overwrite the file descriptor with the write-end of a pipe
		383	(the pipe fd will be created on demand and will be cached).
		384
		385	Or in other words: the file descriptor will be closed, but it will not be
		386	free for reuse until the perl filehandle is closed.
		387
		388	=cut
160		389
161	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	390	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
162		391
163	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	392	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
164		393
165	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	394	Reads or writes C<$length> bytes from or to the specified C<$fh> and
166	into the scalar given by C<data> and offset C<dataoffset> and calls the	395	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
167	callback without the actual number of bytes read (or -1 on error, just	396	and calls the callback without the actual number of bytes read (or -1 on
168	like the syscall).	397	error, just like the syscall).
		398
		399	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		400	offset plus the actual number of bytes read.
		401
		402	If C<$offset> is undefined, then the current file descriptor offset will
		403	be used (and updated), otherwise the file descriptor offset will not be
		404	changed by these calls.
		405
		406	If C<$length> is undefined in C<aio_write>, use the remaining length of
		407	C<$data>.
		408
		409	If C<$dataoffset> is less than zero, it will be counted from the end of
		410	C<$data>.
169		411
170	The C<$data> scalar I<MUST NOT> be modified in any way while the request	412	The C<$data> scalar I<MUST NOT> be modified in any way while the request
171	is outstanding. Modifying it can result in segfaults or WW3 (if the	413	is outstanding. Modifying it can result in segfaults or World War III (if
172	necessary/optional hardware is installed).	414	the necessary/optional hardware is installed).
173		415
174	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	416	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
175	offset C<0> within the scalar:	417	offset C<0> within the scalar:
176		418
177	aio_read $fh, 7, 15, $buffer, 0, sub {	419	aio_read $fh, 7, 15, $buffer, 0, sub {
178	$_[0] > 0 or die "read error: $!";	420	$_[0] > 0 or die "read error: $!";
179	print "read $_[0] bytes: <$buffer>\n";	421	print "read $_[0] bytes: <$buffer>\n";
180	};	422	};
181		423
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		424
250	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	425	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
251		426
252	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	427	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
253	reading at byte offset C<$in_offset>, and starts writing at the current	428	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
255	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	430	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
256	other.	431	other.
257		432
258	This call tries to make use of a native C<sendfile> syscall to provide	433	This call tries to make use of a native C<sendfile> syscall to provide
259	zero-copy operation. For this to work, C<$out_fh> should refer to a	434	zero-copy operation. For this to work, C<$out_fh> should refer to a
260	socket, and C<$in_fh> should refer to mmap'able file.	435	socket, and C<$in_fh> should refer to an mmap'able file.
261		436
262	If the native sendfile call fails or is not implemented, it will be	437	If a native sendfile cannot be found or it fails with C<ENOSYS>,
		438	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,
263	emulated, so you can call C<aio_sendfile> on any type of filehandle	439	it will be emulated, so you can call C<aio_sendfile> on any type of
264	regardless of the limitations of the operating system.	440	filehandle regardless of the limitations of the operating system.
265		441
266	Please note, however, that C<aio_sendfile> can read more bytes from	442	Please note, however, that C<aio_sendfile> can read more bytes from
267	C<$in_fh> than are written, and there is no way to find out how many	443	C<$in_fh> than are written, and there is no way to find out how many
268	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	444	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
269	provides the number of bytes written to C<$out_fh>. Only if the result	445	provides the number of bytes written to C<$out_fh>. Only if the result
270	value equals C<$length> one can assume that C<$length> bytes have been	446	value equals C<$length> one can assume that C<$length> bytes have been
271	read.	447	read.
		448
272		449
273	=item aio_readahead $fh,$offset,$length, $callback->($retval)	450	=item aio_readahead $fh,$offset,$length, $callback->($retval)
274		451
275	C<aio_readahead> populates the page cache with data from a file so that	452	C<aio_readahead> populates the page cache with data from a file so that
276	subsequent reads from that file will not block on disk I/O. The C<$offset>	453	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
282	file. The current file offset of the file is left unchanged.	459	file. The current file offset of the file is left unchanged.
283		460
284	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	461	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
285	emulated by simply reading the data, which would have a similar effect.	462	emulated by simply reading the data, which would have a similar effect.
286		463
		464
287	=item aio_stat $fh_or_path, $callback->($status)	465	=item aio_stat $fh_or_path, $callback->($status)
288		466
289	=item aio_lstat $fh, $callback->($status)	467	=item aio_lstat $fh, $callback->($status)
290		468
291	Works like perl's C<stat> or C<lstat> in void context. The callback will	469	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
304	aio_stat "/etc/passwd", sub {	482	aio_stat "/etc/passwd", sub {
305	$_[0] and die "stat failed: $!";	483	$_[0] and die "stat failed: $!";
306	print "size is ", -s _, "\n";	484	print "size is ", -s _, "\n";
307	};	485	};
308		486
		487
		488	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		489
		490	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		491	whether a file handle or path was passed.
		492
		493	On success, the callback is passed a hash reference with the following
		494	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		495	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		496	is passed.
		497
		498	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		499	C<ST_NOSUID>.
		500
		501	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		502	their correct value when available, or to C<0> on systems that do
		503	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		504	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		505	C<ST_NODIRATIME> and C<ST_RELATIME>.
		506
		507	Example: stat C</wd> and dump out the data if successful.
		508
		509	aio_statvfs "/wd", sub {
		510	my $f = $_[0]
		511	or die "statvfs: $!";
		512
		513	use Data::Dumper;
		514	say Dumper $f;
		515	};
		516
		517	# result:
		518	{
		519	bsize => 1024,
		520	bfree => 4333064312,
		521	blocks => 10253828096,
		522	files => 2050765568,
		523	flag => 4096,
		524	favail => 2042092649,
		525	bavail => 4333064312,
		526	ffree => 2042092649,
		527	namemax => 255,
		528	frsize => 1024,
		529	fsid => 1810
		530	}
		531
		532
		533	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		534
		535	Works like perl's C<utime> function (including the special case of $atime
		536	and $mtime being undef). Fractional times are supported if the underlying
		537	syscalls support them.
		538
		539	When called with a pathname, uses utimes(2) if available, otherwise
		540	utime(2). If called on a file descriptor, uses futimes(2) if available,
		541	otherwise returns ENOSYS, so this is not portable.
		542
		543	Examples:
		544
		545	# set atime and mtime to current time (basically touch(1)):
		546	aio_utime "path", undef, undef;
		547	# set atime to current time and mtime to beginning of the epoch:
		548	aio_utime "path", time, undef; # undef==0
		549
		550
		551	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		552
		553	Works like perl's C<chown> function, except that C<undef> for either $uid
		554	or $gid is being interpreted as "do not change" (but -1 can also be used).
		555
		556	Examples:
		557
		558	# same as "chown root path" in the shell:
		559	aio_chown "path", 0, -1;
		560	# same as above:
		561	aio_chown "path", 0, undef;
		562
		563
		564	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		565
		566	Works like truncate(2) or ftruncate(2).
		567
		568
		569	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		570
		571	Works like perl's C<chmod> function.
		572
		573
309	=item aio_unlink $pathname, $callback->($status)	574	=item aio_unlink $pathname, $callback->($status)
310		575
311	Asynchronously unlink (delete) a file and call the callback with the	576	Asynchronously unlink (delete) a file and call the callback with the
312	result code.	577	result code.
313		578
		579
		580	=item aio_mknod $path, $mode, $dev, $callback->($status)
		581
		582	[EXPERIMENTAL]
		583
		584	Asynchronously create a device node (or fifo). See mknod(2).
		585
		586	The only (POSIX-) portable way of calling this function is:
		587
		588	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		589
		590
314	=item aio_link $srcpath, $dstpath, $callback->($status)	591	=item aio_link $srcpath, $dstpath, $callback->($status)
315		592
316	Asynchronously create a new link to the existing object at C<$srcpath> at	593	Asynchronously create a new link to the existing object at C<$srcpath> at
317	the path C<$dstpath> and call the callback with the result code.	594	the path C<$dstpath> and call the callback with the result code.
318		595
		596
319	=item aio_symlink $srcpath, $dstpath, $callback->($status)	597	=item aio_symlink $srcpath, $dstpath, $callback->($status)
320		598
321	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	599	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
322	the path C<$dstpath> and call the callback with the result code.	600	the path C<$dstpath> and call the callback with the result code.
323		601
		602
		603	=item aio_readlink $path, $callback->($link)
		604
		605	Asynchronously read the symlink specified by C<$path> and pass it to
		606	the callback. If an error occurs, nothing or undef gets passed to the
		607	callback.
		608
		609
324	=item aio_rename $srcpath, $dstpath, $callback->($status)	610	=item aio_rename $srcpath, $dstpath, $callback->($status)
325		611
326	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	612	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
327	rename(2) and call the callback with the result code.	613	rename(2) and call the callback with the result code.
328		614
		615
		616	=item aio_mkdir $pathname, $mode, $callback->($status)
		617
		618	Asynchronously mkdir (create) a directory and call the callback with
		619	the result code. C<$mode> will be modified by the umask at the time the
		620	request is executed, so do not change your umask.
		621
		622
329	=item aio_rmdir $pathname, $callback->($status)	623	=item aio_rmdir $pathname, $callback->($status)
330		624
331	Asynchronously rmdir (delete) a directory and call the callback with the	625	Asynchronously rmdir (delete) a directory and call the callback with the
332	result code.	626	result code.
		627
333		628
334	=item aio_readdir $pathname, $callback->($entries)	629	=item aio_readdir $pathname, $callback->($entries)
335		630
336	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	631	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
337	directory (i.e. opendir + readdir + closedir). The entries will not be	632	directory (i.e. opendir + readdir + closedir). The entries will not be
338	sorted, and will B<NOT> include the C<.> and C<..> entries.	633	sorted, and will B<NOT> include the C<.> and C<..> entries.
339		634
340	The callback a single argument which is either C<undef> or an array-ref	635	The callback is passed a single argument which is either C<undef> or an
341	with the filenames.	636	array-ref with the filenames.
		637
		638
		639	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		640
		641	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		642	behaviour and output format. In case of an error, C<$entries> will be
		643	C<undef>.
		644
		645	The flags are a combination of the following constants, ORed together (the
		646	flags will also be passed to the callback, possibly modified):
		647
		648	=over 4
		649
		650	=item IO::AIO::READDIR_DENTS
		651
		652	When this flag is off, then the callback gets an arrayref with of names
		653	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		654	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		655	entry in more detail.
		656
		657	C<$name> is the name of the entry.
		658
		659	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		660
		661	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		662	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		663	C<IO::AIO::DT_WHT>.
		664
		665	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		666	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		667	scalars are read-only: you can not modify them.
		668
		669	C<$inode> is the inode number (which might not be exact on systems with 64
		670	bit inode numbers and 32 bit perls). This field has unspecified content on
		671	systems that do not deliver the inode information.
		672
		673	=item IO::AIO::READDIR_DIRS_FIRST
		674
		675	When this flag is set, then the names will be returned in an order where
		676	likely directories come first. This is useful when you need to quickly
		677	find directories, or you want to find all directories while avoiding to
		678	stat() each entry.
		679
		680	If the system returns type information in readdir, then this is used
		681	to find directories directly. Otherwise, likely directories are files
		682	beginning with ".", or otherwise files with no dots, of which files with
		683	short names are tried first.
		684
		685	=item IO::AIO::READDIR_STAT_ORDER
		686
		687	When this flag is set, then the names will be returned in an order
		688	suitable for stat()'ing each one. That is, when you plan to stat()
		689	all files in the given directory, then the returned order will likely
		690	be fastest.
		691
		692	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		693	the likely dirs come first, resulting in a less optimal stat order.
		694
		695	=item IO::AIO::READDIR_FOUND_UNKNOWN
		696
		697	This flag should not be set when calling C<aio_readdirx>. Instead, it
		698	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		699	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		700	C<$type>'s are known, which can be used to speed up some algorithms.
		701
		702	=back
		703
		704
		705	=item aio_load $path, $data, $callback->($status)
		706
		707	This is a composite request that tries to fully load the given file into
		708	memory. Status is the same as with aio_read.
		709
		710	=cut
		711
		712	sub aio_load($$;$) {
		713	my ($path, undef, $cb) = @_;
		714	my $data = \$_[1];
		715
		716	my $pri = aioreq_pri;
		717	my $grp = aio_group $cb;
		718
		719	aioreq_pri $pri;
		720	add $grp aio_open $path, O_RDONLY, 0, sub {
		721	my $fh = shift
		722	or return $grp->result (-1);
		723
		724	aioreq_pri $pri;
		725	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		726	$grp->result ($_[0]);
		727	};
		728	};
		729
		730	$grp
		731	}
		732
		733	=item aio_copy $srcpath, $dstpath, $callback->($status)
		734
		735	Try to copy the I<file> (directories not supported as either source or
		736	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		737	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		738
		739	This is a composite request that creates the destination file with
		740	mode 0200 and copies the contents of the source file into it using
		741	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		742	uid/gid, in that order.
		743
		744	If an error occurs, the partial destination file will be unlinked, if
		745	possible, except when setting atime, mtime, access mode and uid/gid, where
		746	errors are being ignored.
		747
		748	=cut
		749
		750	sub aio_copy($$;$) {
		751	my ($src, $dst, $cb) = @_;
		752
		753	my $pri = aioreq_pri;
		754	my $grp = aio_group $cb;
		755
		756	aioreq_pri $pri;
		757	add $grp aio_open $src, O_RDONLY, 0, sub {
		758	if (my $src_fh = $_[0]) {
		759	my @stat = stat $src_fh; # hmm, might block over nfs?
		760
		761	aioreq_pri $pri;
		762	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		763	if (my $dst_fh = $_[0]) {
		764	aioreq_pri $pri;
		765	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		766	if ($_[0] == $stat[7]) {
		767	$grp->result (0);
		768	close $src_fh;
		769
		770	my $ch = sub {
		771	aioreq_pri $pri;
		772	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		773	aioreq_pri $pri;
		774	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		775	aioreq_pri $pri;
		776	add $grp aio_close $dst_fh;
		777	}
		778	};
		779	};
		780
		781	aioreq_pri $pri;
		782	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		783	if ($_[0] < 0 && $! == ENOSYS) {
		784	aioreq_pri $pri;
		785	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		786	} else {
		787	$ch->();
		788	}
		789	};
		790	} else {
		791	$grp->result (-1);
		792	close $src_fh;
		793	close $dst_fh;
		794
		795	aioreq $pri;
		796	add $grp aio_unlink $dst;
		797	}
		798	};
		799	} else {
		800	$grp->result (-1);
		801	}
		802	},
		803
		804	} else {
		805	$grp->result (-1);
		806	}
		807	};
		808
		809	$grp
		810	}
		811
		812	=item aio_move $srcpath, $dstpath, $callback->($status)
		813
		814	Try to move the I<file> (directories not supported as either source or
		815	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		816	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		817
		818	This is a composite request that tries to rename(2) the file first; if
		819	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		820	that is successful, unlinks the C<$srcpath>.
		821
		822	=cut
		823
		824	sub aio_move($$;$) {
		825	my ($src, $dst, $cb) = @_;
		826
		827	my $pri = aioreq_pri;
		828	my $grp = aio_group $cb;
		829
		830	aioreq_pri $pri;
		831	add $grp aio_rename $src, $dst, sub {
		832	if ($_[0] && $! == EXDEV) {
		833	aioreq_pri $pri;
		834	add $grp aio_copy $src, $dst, sub {
		835	$grp->result ($_[0]);
		836
		837	if (!$_[0]) {
		838	aioreq_pri $pri;
		839	add $grp aio_unlink $src;
		840	}
		841	};
		842	} else {
		843	$grp->result ($_[0]);
		844	}
		845	};
		846
		847	$grp
		848	}
342		849
343	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	850	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
344		851
345	Scans a directory (similar to C<aio_readdir>) but additionally tries to	852	Scans a directory (similar to C<aio_readdir>) but additionally tries to
346	separate the entries of directory C<$path> into two sets of names, ones	853	efficiently separate the entries of directory C<$path> into two sets of
347	you can recurse into (directories or links to them), and ones you cannot	854	names, directories you can recurse into (directories), and ones you cannot
348	recurse into (everything else).	855	recurse into (everything else, including symlinks to directories).
349		856
350	C<aio_scandir> is a composite request that consists of many sub	857	C<aio_scandir> is a composite request that creates of many sub requests_
351	requests. C<$maxreq> specifies the maximum number of outstanding aio	858	C<$maxreq> specifies the maximum number of outstanding aio requests that
352	requests that this function generates. If it is C<< <= 0 >>, then a	859	this function generates. If it is C<< <= 0 >>, then a suitable default
353	suitable default will be chosen (currently 8).	860	will be chosen (currently 4).
354		861
355	On error, the callback is called without arguments, otherwise it receives	862	On error, the callback is called without arguments, otherwise it receives
356	two array-refs with path-relative entry names.	863	two array-refs with path-relative entry names.
357		864
358	Example:	865	Example:
…		…
365		872
366	Implementation notes.	873	Implementation notes.
367		874
368	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	875	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
369		876
		877	If readdir returns file type information, then this is used directly to
		878	find directories.
		879
370	After reading the directory, the modification time, size etc. of the	880	Otherwise, after reading the directory, the modification time, size etc.
371	directory before and after the readdir is checked, and if they match (and	881	of the directory before and after the readdir is checked, and if they
372	isn't the current time), the link count will be used to decide how many	882	match (and isn't the current time), the link count will be used to decide
373	entries are directories (if >= 2). Otherwise, no knowledge of the number	883	how many entries are directories (if >= 2). Otherwise, no knowledge of the
374	of subdirectories will be assumed.	884	number of subdirectories will be assumed.
375		885
376	Then entries will be sorted into likely directories (everything without	886	Then entries will be sorted into likely directories a non-initial dot
377	a non-initial dot currently) and likely non-directories (everything	887	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,	888	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	889	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	890	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	891	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	892	filesystems might detect the type of the entry without reading the inode
383	data (e.g. ext2fs filetype feature).	893	data (e.g. ext2fs filetype feature), even on systems that cannot return
		894	the filetype information on readdir.
384		895
385	If the known number of directories (link count - 2) has been reached, the	896	If the known number of directories (link count - 2) has been reached, the
386	rest of the entries is assumed to be non-directories.	897	rest of the entries is assumed to be non-directories.
387		898
388	This only works with certainty on POSIX (= UNIX) filesystems, which	899	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	903	as those tend to return 0 or 1 as link counts, which disables the
393	directory counting heuristic.	904	directory counting heuristic.
394		905
395	=cut	906	=cut
396		907
397	sub aio_scandir($$$) {	908	sub aio_scandir($$;$) {
398	my ($path, $maxreq, $cb) = @_;	909	my ($path, $maxreq, $cb) = @_;
399		910
		911	my $pri = aioreq_pri;
		912
400	my $grp = aio_group;	913	my $grp = aio_group $cb;
401		914
402	$maxreq = 8 if $maxreq <= 0;	915	$maxreq = 4 if $maxreq <= 0;
403		916
404	# stat once	917	# stat once
		918	aioreq_pri $pri;
405	add $grp aio_stat $path, sub {	919	add $grp aio_stat $path, sub {
406	return $cb->() if $_[0];	920	return $grp->result () if $_[0];
407	my $now = time;	921	my $now = time;
408	my $hash1 = join ":", (stat _)[0,1,3,7,9];	922	my $hash1 = join ":", (stat _)[0,1,3,7,9];
409		923
410	# read the directory entries	924	# read the directory entries
		925	aioreq_pri $pri;
411	add $grp aio_readdir $path, sub {	926	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
412	my $entries = shift	927	my $entries = shift
413	or return $cb->();	928	or return $grp->result ();
414		929
415	# stat the dir another time	930	# stat the dir another time
		931	aioreq_pri $pri;
416	add $grp aio_stat $path, sub {	932	add $grp aio_stat $path, sub {
417	my $hash2 = join ":", (stat _)[0,1,3,7,9];	933	my $hash2 = join ":", (stat _)[0,1,3,7,9];
418		934
419	my $ndirs;	935	my $ndirs;
420		936
421	# take the slow route if anything looks fishy	937	# take the slow route if anything looks fishy
422	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	938	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
423	$ndirs = -1;	939	$ndirs = -1;
424	} else {	940	} else {
425	# if nlink == 2, we are finished	941	# if nlink == 2, we are finished
426	# on non-posix-fs's, we rely on nlink < 2	942	# for non-posix-fs's, we rely on nlink < 2
427	$ndirs = (stat _)[3] - 2	943	$ndirs = (stat _)[3] - 2
428	or return $cb->([], $entries);	944	or return $grp->result ([], $entries);
429	}	945	}
430		946
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	@$entries];
437
438	my (@dirs, @nondirs);	947	my (@dirs, @nondirs);
439		948
440	my ($statcb, $schedcb);	949	my $statgrp = add $grp aio_group sub {
441	my $nreq = 0;	950	$grp->result (\@dirs, \@nondirs);
		951	};
442		952
443	$schedcb = sub {	953	limit $statgrp $maxreq;
444	if (@$entries) {	954	feed $statgrp sub {
445	if ($nreq < $maxreq) {	955	return unless @$entries;
446	my $ent = pop @$entries;	956	my $entry = shift @$entries;
		957
		958	aioreq_pri $pri;
		959	add $statgrp aio_stat "$path/$entry/.", sub {
		960	if ($_[0] < 0) {
		961	push @nondirs, $entry;
		962	} else {
		963	# need to check for real directory
		964	aioreq_pri $pri;
		965	add $statgrp aio_lstat "$path/$entry", sub {
		966	if (-d _) {
		967	push @dirs, $entry;
		968
		969	unless (--$ndirs) {
		970	push @nondirs, @$entries;
		971	feed $statgrp;
		972	}
		973	} else {
		974	push @nondirs, $entry;
		975	}
447	$nreq++;	976	}
448	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
449	}	977	}
450	} elsif (!$nreq) {
451	# finished
452	undef $statcb;
453	undef $schedcb;
454	$cb->(\@dirs, \@nondirs) if $cb;
455	undef $cb;
456	}	978	};
457	};	979	};
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	};	980	};
488	};	981	};
489	};	982	};
490		983
491	$grp	984	$grp
492	}	985	}
493		986
		987	=item aio_rmtree $path, $callback->($status)
		988
		989	Delete a directory tree starting (and including) C<$path>, return the
		990	status of the final C<rmdir> only. This is a composite request that
		991	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		992	everything else.
		993
		994	=cut
		995
		996	sub aio_rmtree;
		997	sub aio_rmtree($;$) {
		998	my ($path, $cb) = @_;
		999
		1000	my $pri = aioreq_pri;
		1001	my $grp = aio_group $cb;
		1002
		1003	aioreq_pri $pri;
		1004	add $grp aio_scandir $path, 0, sub {
		1005	my ($dirs, $nondirs) = @_;
		1006
		1007	my $dirgrp = aio_group sub {
		1008	add $grp aio_rmdir $path, sub {
		1009	$grp->result ($_[0]);
		1010	};
		1011	};
		1012
		1013	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1014	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1015
		1016	add $grp $dirgrp;
		1017	};
		1018
		1019	$grp
		1020	}
		1021
		1022	=item aio_sync $callback->($status)
		1023
		1024	Asynchronously call sync and call the callback when finished.
		1025
494	=item aio_fsync $fh, $callback->($status)	1026	=item aio_fsync $fh, $callback->($status)
495		1027
496	Asynchronously call fsync on the given filehandle and call the callback	1028	Asynchronously call fsync on the given filehandle and call the callback
497	with the fsync result code.	1029	with the fsync result code.
498		1030
…		…
502	callback with the fdatasync result code.	1034	callback with the fdatasync result code.
503		1035
504	If this call isn't available because your OS lacks it or it couldn't be	1036	If this call isn't available because your OS lacks it or it couldn't be
505	detected, it will be emulated by calling C<fsync> instead.	1037	detected, it will be emulated by calling C<fsync> instead.
506		1038
		1039	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1040
		1041	Sync the data portion of the file specified by C<$offset> and C<$length>
		1042	to disk (but NOT the metadata), by calling the Linux-specific
		1043	sync_file_range call. If sync_file_range is not available or it returns
		1044	ENOSYS, then fdatasync or fsync is being substituted.
		1045
		1046	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1047	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1048	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1049	manpage for details.
		1050
		1051	=item aio_pathsync $path, $callback->($status)
		1052
		1053	This request tries to open, fsync and close the given path. This is a
		1054	composite request intended to sync directories after directory operations
		1055	(E.g. rename). This might not work on all operating systems or have any
		1056	specific effect, but usually it makes sure that directory changes get
		1057	written to disc. It works for anything that can be opened for read-only,
		1058	not just directories.
		1059
		1060	Future versions of this function might fall back to other methods when
		1061	C<fsync> on the directory fails (such as calling C<sync>).
		1062
		1063	Passes C<0> when everything went ok, and C<-1> on error.
		1064
		1065	=cut
		1066
		1067	sub aio_pathsync($;$) {
		1068	my ($path, $cb) = @_;
		1069
		1070	my $pri = aioreq_pri;
		1071	my $grp = aio_group $cb;
		1072
		1073	aioreq_pri $pri;
		1074	add $grp aio_open $path, O_RDONLY, 0, sub {
		1075	my ($fh) = @_;
		1076	if ($fh) {
		1077	aioreq_pri $pri;
		1078	add $grp aio_fsync $fh, sub {
		1079	$grp->result ($_[0]);
		1080
		1081	aioreq_pri $pri;
		1082	add $grp aio_close $fh;
		1083	};
		1084	} else {
		1085	$grp->result (-1);
		1086	}
		1087	};
		1088
		1089	$grp
		1090	}
		1091
		1092	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1093
		1094	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1095	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1096	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1097	scalar must only be modified in-place while an aio operation is pending on
		1098	it).
		1099
		1100	It calls the C<msync> function of your OS, if available, with the memory
		1101	area starting at C<$offset> in the string and ending C<$length> bytes
		1102	later. If C<$length> is negative, counts from the end, and if C<$length>
		1103	is C<undef>, then it goes till the end of the string. The flags can be
		1104	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1105	C<IO::AIO::MS_SYNC>.
		1106
		1107	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1108
		1109	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1110	scalars.
		1111
		1112	It touches (reads or writes) all memory pages in the specified
		1113	range inside the scalar. All caveats and parameters are the same
		1114	as for C<aio_msync>, above, except for flags, which must be either
		1115	C<0> (which reads all pages and ensures they are instantiated) or
		1116	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1117	writing an octet from it, which dirties the page).
		1118
		1119	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1120
		1121	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1122	scalars.
		1123
		1124	It reads in all the pages of the underlying storage into memory (if any)
		1125	and locks them, so they are not getting swapped/paged out or removed.
		1126
		1127	If C<$length> is undefined, then the scalar will be locked till the end.
		1128
		1129	On systems that do not implement C<mlock>, this function returns C<-1>
		1130	and sets errno to C<ENOSYS>.
		1131
		1132	Note that the corresponding C<munlock> is synchronous and is
		1133	documented under L<MISCELLANEOUS FUNCTIONS>.
		1134
		1135	Example: open a file, mmap and mlock it - both will be undone when
		1136	C<$data> gets destroyed.
		1137
		1138	open my $fh, "<", $path or die "$path: $!";
		1139	my $data;
		1140	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1141	aio_mlock $data; # mlock in background
		1142
		1143	=item aio_mlockall $flags, $callback->($status)
		1144
		1145	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1146	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1147
		1148	On systems that do not implement C<mlockall>, this function returns C<-1>
		1149	and sets errno to C<ENOSYS>.
		1150
		1151	Note that the corresponding C<munlockall> is synchronous and is
		1152	documented under L<MISCELLANEOUS FUNCTIONS>.
		1153
		1154	Example: asynchronously lock all current and future pages into memory.
		1155
		1156	aio_mlockall IO::AIO::MCL_FUTURE;
		1157
507	=item aio_group $callback->()	1158	=item aio_group $callback->(...)
508
509	[EXPERIMENTAL]
510		1159
511	This is a very special aio request: Instead of doing something, it is a	1160	This is a very special aio request: Instead of doing something, it is a
512	container for other aio requests, which is useful if you want to bundle	1161	container for other aio requests, which is useful if you want to bundle
513	many requests into a single, composite, request.	1162	many requests into a single, composite, request with a definite callback
		1163	and the ability to cancel the whole request with its subrequests.
514		1164
515	Returns an object of class L<IO::AIO::GRP>. See its documentation below	1165	Returns an object of class L<IO::AIO::GRP>. See its documentation below
516	for more info.	1166	for more info.
517		1167
518	Example:	1168	Example:
…		…
524	add $grp	1174	add $grp
525	(aio_stat ...),	1175	(aio_stat ...),
526	(aio_stat ...),	1176	(aio_stat ...),
527	...;	1177	...;
528		1178
		1179	=item aio_nop $callback->()
		1180
		1181	This is a special request - it does nothing in itself and is only used for
		1182	side effects, such as when you want to add a dummy request to a group so
		1183	that finishing the requests in the group depends on executing the given
		1184	code.
		1185
		1186	While this request does nothing, it still goes through the execution
		1187	phase and still requires a worker thread. Thus, the callback will not
		1188	be executed immediately but only after other requests in the queue have
		1189	entered their execution phase. This can be used to measure request
		1190	latency.
		1191
529	=item aio_sleep $fractional_seconds, $callback->() *NOT EXPORTED*	1192	=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED*
530		1193
531	Mainly used for debugging and benchmarking, this aio request puts one of	1194	Mainly used for debugging and benchmarking, this aio request puts one of
532	the request workers to sleep for the given time.	1195	the request workers to sleep for the given time.
533		1196
		1197	While it is theoretically handy to have simple I/O scheduling requests
		1198	like sleep and file handle readable/writable, the overhead this creates is
		1199	immense (it blocks a thread for a long time) so do not use this function
		1200	except to put your application under artificial I/O pressure.
		1201
534	=back	1202	=back
535		1203
536	=head2 IO::AIO::REQ CLASS	1204	=head2 IO::AIO::REQ CLASS
537		1205
538	All non-aggregate C<aio_*> functions return an object of this class when	1206	All non-aggregate C<aio_*> functions return an object of this class when
539	called in non-void context.	1207	called in non-void context.
540		1208
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	1209	=over 4
550		1210
551	=item $req->cancel	1211	=item cancel $req
552		1212
553	Cancels the request, if possible. Has the effect of skipping execution	1213	Cancels the request, if possible. Has the effect of skipping execution
554	when entering the B<execute> state and skipping calling the callback when	1214	when entering the B<execute> state and skipping calling the callback when
555	entering the the B<result> state, but will leave the request otherwise	1215	entering the the B<result> state, but will leave the request otherwise
556	untouched. That means that requests that currently execute will not be	1216	untouched (with the exception of readdir). That means that requests that
557	stopped and resources held by the request will not be freed prematurely.	1217	currently execute will not be stopped and resources held by the request
		1218	will not be freed prematurely.
		1219
		1220	=item cb $req $callback->(...)
		1221
		1222	Replace (or simply set) the callback registered to the request.
558		1223
559	=back	1224	=back
560		1225
561	=head2 IO::AIO::GRP CLASS	1226	=head2 IO::AIO::GRP CLASS
562		1227
…		…
577	You add requests by calling the C<add> method with one or more	1242	You add requests by calling the C<add> method with one or more
578	C<IO::AIO::REQ> objects:	1243	C<IO::AIO::REQ> objects:
579		1244
580	$grp->add (aio_unlink "...");	1245	$grp->add (aio_unlink "...");
581		1246
582	add $grp aio_stat "...", sub { ... };	1247	add $grp aio_stat "...", sub {
		1248	$_[0] or return $grp->result ("error");
		1249
		1250	# add another request dynamically, if first succeeded
		1251	add $grp aio_open "...", sub {
		1252	$grp->result ("ok");
		1253	};
		1254	};
583		1255
584	This makes it very easy to create composite requests (see the source of	1256	This makes it very easy to create composite requests (see the source of
585	C<aio_move> for an application) that work and feel like simple requests.	1257	C<aio_move> for an application) that work and feel like simple requests.
586		1258
		1259	=over 4
		1260
587	The IO::AIO::GRP objects will be cleaned up during calls to	1261	=item * The IO::AIO::GRP objects will be cleaned up during calls to
588	C<IO::AIO::poll_cb>, just like any other request.	1262	C<IO::AIO::poll_cb>, just like any other request.
589		1263
590	They can be canceled like any other request. Canceling will cancel not	1264	=item * They can be canceled like any other request. Canceling will cancel not
591	just the request itself, but also all requests it contains.	1265	only the request itself, but also all requests it contains.
592		1266
593	They can also can also be added to other IO::AIO::GRP objects.	1267	=item * They can also can also be added to other IO::AIO::GRP objects.
		1268
		1269	=item * You must not add requests to a group from within the group callback (or
		1270	any later time).
		1271
		1272	=back
594		1273
595	Their lifetime, simplified, looks like this: when they are empty, they	1274	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	1275	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	1276	C<done> state, they will also finish. Otherwise they will continue to
598	exist.	1277	exist.
599		1278
		1279	That means after creating a group you have some time to add requests
		1280	(precisely before the callback has been invoked, which is only done within
		1281	the C<poll_cb>). And in the callbacks of those requests, you can add
		1282	further requests to the group. And only when all those requests have
		1283	finished will the the group itself finish.
		1284
600	=over 4	1285	=over 4
601		1286
		1287	=item add $grp ...
		1288
602	=item $grp->add (...)	1289	=item $grp->add (...)
603		1290
604	=item add $grp ...	1291	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		1292	be added, including other groups, as long as you do not create circular
		1293	dependencies.
605		1294
606	Add one or more	1295	Returns all its arguments.
607	Cancels the request, if possible. Has the effect of skipping execution	1296
608	when entering the B<execute> state and skipping calling the callback when	1297	=item $grp->cancel_subs
609	entering the the B<result> state, but will leave the request otherwise	1298
610	untouched. That means that requests that currently execute will not be	1299	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.	1300	itself. Useful when you queued a lot of events but got a result early.
		1301
		1302	The group request will finish normally (you cannot add requests to the
		1303	group).
		1304
		1305	=item $grp->result (...)
		1306
		1307	Set the result value(s) that will be passed to the group callback when all
		1308	subrequests have finished and set the groups errno to the current value
		1309	of errno (just like calling C<errno> without an error number). By default,
		1310	no argument will be passed and errno is zero.
		1311
		1312	=item $grp->errno ([$errno])
		1313
		1314	Sets the group errno value to C<$errno>, or the current value of errno
		1315	when the argument is missing.
		1316
		1317	Every aio request has an associated errno value that is restored when
		1318	the callback is invoked. This method lets you change this value from its
		1319	default (0).
		1320
		1321	Calling C<result> will also set errno, so make sure you either set C<$!>
		1322	before the call to C<result>, or call c<errno> after it.
		1323
		1324	=item feed $grp $callback->($grp)
		1325
		1326	Sets a feeder/generator on this group: every group can have an attached
		1327	generator that generates requests if idle. The idea behind this is that,
		1328	although you could just queue as many requests as you want in a group,
		1329	this might starve other requests for a potentially long time. For example,
		1330	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
		1331	delaying any later requests for a long time.
		1332
		1333	To avoid this, and allow incremental generation of requests, you can
		1334	instead a group and set a feeder on it that generates those requests. The
		1335	feed callback will be called whenever there are few enough (see C<limit>,
		1336	below) requests active in the group itself and is expected to queue more
		1337	requests.
		1338
		1339	The feed callback can queue as many requests as it likes (i.e. C<add> does
		1340	not impose any limits).
		1341
		1342	If the feed does not queue more requests when called, it will be
		1343	automatically removed from the group.
		1344
		1345	If the feed limit is C<0> when this method is called, it will be set to
		1346	C<2> automatically.
		1347
		1348	Example:
		1349
		1350	# stat all files in @files, but only ever use four aio requests concurrently:
		1351
		1352	my $grp = aio_group sub { print "finished\n" };
		1353	limit $grp 4;
		1354	feed $grp sub {
		1355	my $file = pop @files
		1356	or return;
		1357
		1358	add $grp aio_stat $file, sub { ... };
		1359	};
		1360
		1361	=item limit $grp $num
		1362
		1363	Sets the feeder limit for the group: The feeder will be called whenever
		1364	the group contains less than this many requests.
		1365
		1366	Setting the limit to C<0> will pause the feeding process.
		1367
		1368	The default value for the limit is C<0>, but note that setting a feeder
		1369	automatically bumps it up to C<2>.
612		1370
613	=back	1371	=back
614		1372
615	=head2 SUPPORT FUNCTIONS	1373	=head2 SUPPORT FUNCTIONS
616		1374
		1375	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1376
617	=over 4	1377	=over 4
618		1378
619	=item $fileno = IO::AIO::poll_fileno	1379	=item $fileno = IO::AIO::poll_fileno
620		1380
621	Return the I<request result pipe file descriptor>. This filehandle must be	1381	Return the I<request result pipe file descriptor>. This filehandle must be
622	polled for reading by some mechanism outside this module (e.g. Event or	1382	polled for reading by some mechanism outside this module (e.g. EV, Glib,
623	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1383	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
624	to call C<poll_cb> to check the results.	1384	you have to call C<poll_cb> to check the results.
625		1385
626	See C<poll_cb> for an example.	1386	See C<poll_cb> for an example.
627		1387
628	=item IO::AIO::poll_cb	1388	=item IO::AIO::poll_cb
629		1389
630	Process all outstanding events on the result pipe. You have to call this	1390	Process some outstanding events on the result pipe. You have to call this
631	regularly. Returns the number of events processed. Returns immediately	1391	regularly. Returns C<0> if all events could be processed, or C<-1> if it
632	when no events are outstanding.	1392	returned earlier for whatever reason. Returns immediately when no events
		1393	are outstanding. The amount of events processed depends on the settings of
		1394	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1395
		1396	If not all requests were processed for whatever reason, the filehandle
		1397	will still be ready when C<poll_cb> returns, so normally you don't have to
		1398	do anything special to have it called later.
633		1399
634	Example: Install an Event watcher that automatically calls	1400	Example: Install an Event watcher that automatically calls
635	IO::AIO::poll_cb with high priority:	1401	IO::AIO::poll_cb with high priority (more examples can be found in the
		1402	SYNOPSIS section, at the top of this document):
636		1403
637	Event->io (fd => IO::AIO::poll_fileno,	1404	Event->io (fd => IO::AIO::poll_fileno,
638	poll => 'r', async => 1,	1405	poll => 'r', async => 1,
639	cb => \&IO::AIO::poll_cb);	1406	cb => \&IO::AIO::poll_cb);
640		1407
641	=item IO::AIO::poll_wait	1408	=item IO::AIO::poll_wait
642		1409
		1410	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	1411	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	1412	does a C<select> on the filehandle. This is useful if you want to
645	for some requests to finish).	1413	synchronously wait for some requests to finish).
646		1414
647	See C<nreqs> for an example.	1415	See C<nreqs> for an example.
648		1416
		1417	=item IO::AIO::poll
		1418
		1419	Waits until some requests have been handled.
		1420
		1421	Returns the number of requests processed, but is otherwise strictly
		1422	equivalent to:
		1423
		1424	IO::AIO::poll_wait, IO::AIO::poll_cb
		1425
649	=item IO::AIO::nreqs	1426	=item IO::AIO::flush
650		1427
651	Returns the number of requests currently outstanding (i.e. for which their	1428	Wait till all outstanding AIO requests have been handled.
652	callback has not been invoked yet).
653		1429
654	Example: wait till there are no outstanding requests anymore:	1430	Strictly equivalent to:
655		1431
656	IO::AIO::poll_wait, IO::AIO::poll_cb	1432	IO::AIO::poll_wait, IO::AIO::poll_cb
657	while IO::AIO::nreqs;	1433	while IO::AIO::nreqs;
658		1434
659	=item IO::AIO::flush	1435	=item IO::AIO::max_poll_reqs $nreqs
660		1436
661	Wait till all outstanding AIO requests have been handled.	1437	=item IO::AIO::max_poll_time $seconds
662		1438
663	Strictly equivalent to:	1439	These set the maximum number of requests (default C<0>, meaning infinity)
		1440	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1441	the maximum amount of time (default C<0>, meaning infinity) spent in
		1442	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1443	of time C<poll_cb> is allowed to use).
664		1444
665	IO::AIO::poll_wait, IO::AIO::poll_cb	1445	Setting C<max_poll_time> to a non-zero value creates an overhead of one
666	while IO::AIO::nreqs;	1446	syscall per request processed, which is not normally a problem unless your
		1447	callbacks are really really fast or your OS is really really slow (I am
		1448	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
667		1449
668	=item IO::AIO::poll	1450	Setting these is useful if you want to ensure some level of
		1451	interactiveness when perl is not fast enough to process all requests in
		1452	time.
669		1453
670	Waits until some requests have been handled.	1454	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
671		1455
672	Strictly equivalent to:	1456	Example: Install an Event watcher that automatically calls
		1457	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1458	program get the CPU sometimes even under high AIO load.
673		1459
674	IO::AIO::poll_wait, IO::AIO::poll_cb	1460	# try not to spend much more than 0.1s in poll_cb
675	if IO::AIO::nreqs;	1461	IO::AIO::max_poll_time 0.1;
		1462
		1463	# use a low priority so other tasks have priority
		1464	Event->io (fd => IO::AIO::poll_fileno,
		1465	poll => 'r', nice => 1,
		1466	cb => &IO::AIO::poll_cb);
		1467
		1468	=back
		1469
		1470	=head3 CONTROLLING THE NUMBER OF THREADS
		1471
		1472	=over
676		1473
677	=item IO::AIO::min_parallel $nthreads	1474	=item IO::AIO::min_parallel $nthreads
678		1475
679	Set the minimum number of AIO threads to C<$nthreads>. The current default	1476	Set the minimum number of AIO threads to C<$nthreads>. The current
680	is C<4>, which means four asynchronous operations can be done at one time	1477	default is C<8>, which means eight asynchronous operations can execute
681	(the number of outstanding operations, however, is unlimited).	1478	concurrently at any one time (the number of outstanding requests,
		1479	however, is unlimited).
682		1480
683	IO::AIO starts threads only on demand, when an AIO request is queued and	1481	IO::AIO starts threads only on demand, when an AIO request is queued and
684	no free thread exists.	1482	no free thread exists. Please note that queueing up a hundred requests can
		1483	create demand for a hundred threads, even if it turns out that everything
		1484	is in the cache and could have been processed faster by a single thread.
685		1485
686	It is recommended to keep the number of threads low, as some Linux	1486	It is recommended to keep the number of threads relatively low, as some
687	kernel versions will scale negatively with the number of threads (higher	1487	Linux kernel versions will scale negatively with the number of threads
688	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1488	(higher parallelity => MUCH higher latency). With current Linux 2.6
689	threads should be fine.	1489	versions, 4-32 threads should be fine.
690		1490
691	Under most circumstances you don't need to call this function, as the	1491	Under most circumstances you don't need to call this function, as the
692	module selects a default that is suitable for low to moderate load.	1492	module selects a default that is suitable for low to moderate load.
693		1493
694	=item IO::AIO::max_parallel $nthreads	1494	=item IO::AIO::max_parallel $nthreads
…		…
703	This module automatically runs C<max_parallel 0> at program end, to ensure	1503	This module automatically runs C<max_parallel 0> at program end, to ensure
704	that all threads are killed and that there are no outstanding requests.	1504	that all threads are killed and that there are no outstanding requests.
705		1505
706	Under normal circumstances you don't need to call this function.	1506	Under normal circumstances you don't need to call this function.
707		1507
		1508	=item IO::AIO::max_idle $nthreads
		1509
		1510	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1511	threads that did not get a request to process within 10 seconds). That
		1512	means if a thread becomes idle while C<$nthreads> other threads are also
		1513	idle, it will free its resources and exit.
		1514
		1515	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1516	to allow for extremely high load situations, but want to free resources
		1517	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1518
		1519	The default is probably ok in most situations, especially if thread
		1520	creation is fast. If thread creation is very slow on your system you might
		1521	want to use larger values.
		1522
708	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1523	=item IO::AIO::max_outstanding $maxreqs
		1524
		1525	This is a very bad function to use in interactive programs because it
		1526	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1527	use an C<aio_group> together with a feed callback.
709		1528
710	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1529	Sets the maximum number of outstanding requests to C<$nreqs>. If you
711	try to queue up more than this number of requests, the caller will block until	1530	do queue up more than this number of requests, the next call to the
712	some requests have been handled.	1531	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1532	function will block until the limit is no longer exceeded.
713		1533
714	The default is very large, so normally there is no practical limit. If you	1534	The default value is very large, so there is no practical limit on the
715	queue up many requests in a loop it often improves speed if you set	1535	number of outstanding requests.
716	this to a relatively low number, such as C<100>.
717		1536
718	Under normal circumstances you don't need to call this function.	1537	You can still queue as many requests as you want. Therefore,
		1538	C<max_outstanding> is mainly useful in simple scripts (with low values) or
		1539	as a stop gap to shield against fatal memory overflow (with large values).
719		1540
720	=back	1541	=back
721		1542
		1543	=head3 STATISTICAL INFORMATION
		1544
		1545	=over
		1546
		1547	=item IO::AIO::nreqs
		1548
		1549	Returns the number of requests currently in the ready, execute or pending
		1550	states (i.e. for which their callback has not been invoked yet).
		1551
		1552	Example: wait till there are no outstanding requests anymore:
		1553
		1554	IO::AIO::poll_wait, IO::AIO::poll_cb
		1555	while IO::AIO::nreqs;
		1556
		1557	=item IO::AIO::nready
		1558
		1559	Returns the number of requests currently in the ready state (not yet
		1560	executed).
		1561
		1562	=item IO::AIO::npending
		1563
		1564	Returns the number of requests currently in the pending state (executed,
		1565	but not yet processed by poll_cb).
		1566
		1567	=back
		1568
		1569	=head3 MISCELLANEOUS FUNCTIONS
		1570
		1571	IO::AIO implements some functions that might be useful, but are not
		1572	asynchronous.
		1573
		1574	=over 4
		1575
		1576	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1577
		1578	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1579	but is blocking (this makes most sense if you know the input data is
		1580	likely cached already and the output filehandle is set to non-blocking
		1581	operations).
		1582
		1583	Returns the number of bytes copied, or C<-1> on error.
		1584
		1585	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1586
		1587	Simply calls the C<posix_fadvise> function (see its
		1588	manpage for details). The following advice constants are
		1589	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1590	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1591	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1592
		1593	On systems that do not implement C<posix_fadvise>, this function returns
		1594	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1595
		1596	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1597
		1598	Simply calls the C<posix_madvise> function (see its
		1599	manpage for details). The following advice constants are
		1600	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1601	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1602
		1603	On systems that do not implement C<posix_madvise>, this function returns
		1604	ENOSYS, otherwise the return value of C<posix_madvise>.
		1605
		1606	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1607
		1608	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1609	$scalar (see its manpage for details). The following protect
		1610	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1611	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1612
		1613	On systems that do not implement C<mprotect>, this function returns
		1614	ENOSYS, otherwise the return value of C<mprotect>.
		1615
		1616	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1617
		1618	Memory-maps a file (or anonymous memory range) and attaches it to the
		1619	given C<$scalar>, which will act like a string scalar.
		1620
		1621	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1622	change the string length, and most read-only operations such as copying it
		1623	or searching it with regexes and so on.
		1624
		1625	Anything else is unsafe and will, at best, result in memory leaks.
		1626
		1627	The memory map associated with the C<$scalar> is automatically removed
		1628	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1629	C<IO::AIO::munmap> functions are called.
		1630
		1631	This calls the C<mmap>(2) function internally. See your system's manual
		1632	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1633
		1634	The C<$length> must be larger than zero and smaller than the actual
		1635	filesize.
		1636
		1637	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1638	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1639
		1640	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1641	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1642	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1643	(which is set to C<MAP_ANON> if your system only provides this
		1644	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1645	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1646	C<IO::AIO::MAP_NONBLOCK>
		1647
		1648	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1649
		1650	C<$offset> is the offset from the start of the file - it generally must be
		1651	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1652
		1653	Example:
		1654
		1655	use Digest::MD5;
		1656	use IO::AIO;
		1657
		1658	open my $fh, "<verybigfile"
		1659	or die "$!";
		1660
		1661	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1662	or die "verybigfile: $!";
		1663
		1664	my $fast_md5 = md5 $data;
		1665
		1666	=item IO::AIO::munmap $scalar
		1667
		1668	Removes a previous mmap and undefines the C<$scalar>.
		1669
		1670	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1671
		1672	Calls the C<munlock> function, undoing the effects of a previous
		1673	C<aio_mlock> call (see its description for details).
		1674
		1675	=item IO::AIO::munlockall
		1676
		1677	Calls the C<munlockall> function.
		1678
		1679	On systems that do not implement C<munlockall>, this function returns
		1680	ENOSYS, otherwise the return value of C<munlockall>.
		1681
		1682	=back
		1683
722	=cut	1684	=cut
723		1685
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;	1686	min_parallel 8;
741		1687
742	END {	1688	END { flush }
743	max_parallel 0;
744	}
745		1689
746	1;	1690	1;
		1691
		1692	=head1 EVENT LOOP INTEGRATION
		1693
		1694	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1695	automatically into many event loops:
		1696
		1697	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1698	use AnyEvent::AIO;
		1699
		1700	You can also integrate IO::AIO manually into many event loops, here are
		1701	some examples of how to do this:
		1702
		1703	# EV integration
		1704	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1705
		1706	# Event integration
		1707	Event->io (fd => IO::AIO::poll_fileno,
		1708	poll => 'r',
		1709	cb => \&IO::AIO::poll_cb);
		1710
		1711	# Glib/Gtk2 integration
		1712	add_watch Glib::IO IO::AIO::poll_fileno,
		1713	in => sub { IO::AIO::poll_cb; 1 };
		1714
		1715	# Tk integration
		1716	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1717	readable => \&IO::AIO::poll_cb);
		1718
		1719	# Danga::Socket integration
		1720	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1721	\&IO::AIO::poll_cb);
747		1722
748	=head2 FORK BEHAVIOUR	1723	=head2 FORK BEHAVIOUR
749		1724
750	This module should do "the right thing" when the process using it forks:	1725	This module should do "the right thing" when the process using it forks:
751		1726
752	Before the fork, IO::AIO enters a quiescent state where no requests	1727	Before the fork, IO::AIO enters a quiescent state where no requests
753	can be added in other threads and no results will be processed. After	1728	can be added in other threads and no results will be processed. After
754	the fork the parent simply leaves the quiescent state and continues	1729	the fork the parent simply leaves the quiescent state and continues
755	request/result processing, while the child clears the request/result	1730	request/result processing, while the child frees the request/result queue
756	queue (so the requests started before the fork will only be handled in	1731	(so that the requests started before the fork will only be handled in the
757	the parent). Threads will be started on demand until the limit ste in the	1732	parent). Threads will be started on demand until the limit set in the
758	parent process has been reached again.	1733	parent process has been reached again.
759		1734
760	In short: the parent will, after a short pause, continue as if fork had	1735	In short: the parent will, after a short pause, continue as if fork had
761	not been called, while the child will act as if IO::AIO has not been used	1736	not been called, while the child will act as if IO::AIO has not been used
762	yet.	1737	yet.
763		1738
		1739	=head2 MEMORY USAGE
		1740
		1741	Per-request usage:
		1742
		1743	Each aio request uses - depending on your architecture - around 100-200
		1744	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1745	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1746	scalars and other data passed into aio requests will also be locked and
		1747	will consume memory till the request has entered the done state.
		1748
		1749	This is not awfully much, so queuing lots of requests is not usually a
		1750	problem.
		1751
		1752	Per-thread usage:
		1753
		1754	In the execution phase, some aio requests require more memory for
		1755	temporary buffers, and each thread requires a stack and other data
		1756	structures (usually around 16k-128k, depending on the OS).
		1757
		1758	=head1 KNOWN BUGS
		1759
		1760	Known bugs will be fixed in the next release.
		1761
764	=head1 SEE ALSO	1762	=head1 SEE ALSO
765		1763
766	L<Coro>, L<Linux::AIO> (obsolete).	1764	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1765	more natural syntax.
767		1766
768	=head1 AUTHOR	1767	=head1 AUTHOR
769		1768
770	Marc Lehmann <schmorp@schmorp.de>	1769	Marc Lehmann <schmorp@schmorp.de>
771	http://home.schmorp.de/	1770	http://home.schmorp.de/

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