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Revision 1.147 by root, Wed Jun 3 12:24:49 2009 UTC vs.
Revision 1.304 by root, Wed Apr 3 03:11:45 2019 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	IO::AIO - Asynchronous Input/Output	3	IO::AIO - Asynchronous/Advanced Input/Output
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 = shift	10	my $fh = shift
11	or die "/etc/passwd: $!";	11	or die "/etc/passwd: $!";
12	...	12	...
13	};	13	};
14		14
…		…
26	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
27		27
28	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
29	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
30		30
31	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
32	use AnyEvent::AIO;
33
34	# EV integration
35	my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
36
37	# Event integration
38	Event->io (fd => IO::AIO::poll_fileno,
39	poll => 'r',
40	cb => \&IO::AIO::poll_cb);
41
42	# Glib/Gtk2 integration
43	add_watch Glib::IO IO::AIO::poll_fileno,
44	in => sub { IO::AIO::poll_cb; 1 };
45
46	# Tk integration
47	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
48	readable => \&IO::AIO::poll_cb);
49
50	# Danga::Socket integration
51	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
52	\&IO::AIO::poll_cb);
53
54	=head1 DESCRIPTION	31	=head1 DESCRIPTION
55		32
56	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
57	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>).
58		36
59	Asynchronous means that operations that can normally block your program	37	Asynchronous means that operations that can normally block your program
60	(e.g. reading from disk) will be done asynchronously: the operation	38	(e.g. reading from disk) will be done asynchronously: the operation
61	will still block, but you can do something else in the meantime. This	39	will still block, but you can do something else in the meantime. This
62	is extremely useful for programs that need to stay interactive even	40	is extremely useful for programs that need to stay interactive even
…		…
66	on a RAID volume or over NFS when you do a number of stat operations	44	on a RAID volume or over NFS when you do a number of stat operations
67	concurrently.	45	concurrently.
68		46
69	While most of this works on all types of file descriptors (for	47	While most of this works on all types of file descriptors (for
70	example sockets), using these functions on file descriptors that	48	example sockets), using these functions on file descriptors that
71	support nonblocking operation (again, sockets, pipes etc.) is very	49	support nonblocking operation (again, sockets, pipes etc.) is
72	inefficient. Use an event loop for that (such as the L<Event|Event>	50	very inefficient. Use an event loop for that (such as the L<EV>
73	module): IO::AIO will naturally fit into such an event loop itself.	51	module): IO::AIO will naturally fit into such an event loop itself.
74		52
75	In this version, a number of threads are started that execute your	53	In this version, a number of threads are started that execute your
76	requests and signal their completion. You don't need thread support	54	requests and signal their completion. You don't need thread support
77	in perl, and the threads created by this module will not be visible	55	in perl, and the threads created by this module will not be visible
…		…
80	not well-supported or restricted (GNU/Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
81	files currently, for example), and they would only support aio_read and	59	files currently, for example), and they would only support aio_read and
82	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
83	using threads anyway.	61	using threads anyway.
84		62
		63	In addition to asynchronous I/O, this module also exports some rather
		64	arcane interfaces, such as C<madvise> or linux's C<splice> system call,
		65	which is why the C<A> in C<AIO> can also mean I<advanced>.
		66
85	Although the module will work in the presence of other (Perl-) threads,	67	Although the module will work in the presence of other (Perl-) threads,
86	it is currently not reentrant in any way, so use appropriate locking	68	it is currently not reentrant in any way, so use appropriate locking
87	yourself, always call C<poll_cb> from within the same thread, or never	69	yourself, always call C<poll_cb> from within the same thread, or never
88	call C<poll_cb> (or other C<aio_> functions) recursively.	70	call C<poll_cb> (or other C<aio_> functions) recursively.
89		71
90	=head2 EXAMPLE	72	=head2 EXAMPLE
91		73
92	This is a simple example that uses the Event module and loads	74	This is a simple example that uses the EV module and loads
93	F</etc/passwd> asynchronously:	75	F</etc/passwd> asynchronously:
94		76
95	use Fcntl;
96	use Event;	77	use EV;
97	use IO::AIO;	78	use IO::AIO;
98		79
99	# register the IO::AIO callback with Event	80	# register the IO::AIO callback with EV
100	Event->io (fd => IO::AIO::poll_fileno,	81	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
101	poll => 'r',
102	cb => \&IO::AIO::poll_cb);
103		82
104	# queue the request to open /etc/passwd	83	# queue the request to open /etc/passwd
105	aio_open "/etc/passwd", O_RDONLY, 0, sub {	84	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
106	my $fh = shift	85	my $fh = shift
107	or die "error while opening: $!";	86	or die "error while opening: $!";
108		87
109	# stat'ing filehandles is generally non-blocking	88	# stat'ing filehandles is generally non-blocking
110	my $size = -s $fh;	89	my $size = -s $fh;
…		…
119		98
120	# file contents now in $contents	99	# file contents now in $contents
121	print $contents;	100	print $contents;
122		101
123	# exit event loop and program	102	# exit event loop and program
124	Event::unloop;	103	EV::break;
125	};	104	};
126	};	105	};
127		106
128	# possibly queue up other requests, or open GUI windows,	107	# possibly queue up other requests, or open GUI windows,
129	# check for sockets etc. etc.	108	# check for sockets etc. etc.
130		109
131	# process events as long as there are some:	110	# process events as long as there are some:
132	Event::loop;	111	EV::run;
133		112
134	=head1 REQUEST ANATOMY AND LIFETIME	113	=head1 REQUEST ANATOMY AND LIFETIME
135		114
136	Every C<aio_*> function creates a request. which is a C data structure not	115	Every C<aio_*> function creates a request. which is a C data structure not
137	directly visible to Perl.	116	directly visible to Perl.
…		…
187		166
188	package IO::AIO;	167	package IO::AIO;
189		168
190	use Carp ();	169	use Carp ();
191		170
192	no warnings;	171	use common::sense;
193	use strict 'vars';
194		172
195	use base 'Exporter';	173	use base 'Exporter';
196		174
197	BEGIN {	175	BEGIN {
198	our $VERSION = '3.19';	176	our $VERSION = 4.72;
199		177
200	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	178	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
201	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir	179	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
202	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
203	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead	181	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
		182	aio_pathsync aio_readahead aio_fiemap aio_allocate
204	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
205	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	184	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
206	aio_chmod aio_utime aio_truncate);	185	aio_chmod aio_utime aio_truncate
		186	aio_msync aio_mtouch aio_mlock aio_mlockall
		187	aio_statvfs
		188	aio_slurp
		189	aio_wd);
207		190
208	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	191	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
209	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	192	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
210	min_parallel max_parallel max_idle	193	min_parallel max_parallel max_idle idle_timeout
211	nreqs nready npending nthreads	194	nreqs nready npending nthreads
212	max_poll_time max_poll_reqs);	195	max_poll_time max_poll_reqs
		196	sendfile fadvise madvise
		197	mmap munmap mremap munlock munlockall);
213		198
214	push @AIO_REQ, qw(aio_busy); # not exported	199	push @AIO_REQ, qw(aio_busy); # not exported
215		200
216	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	201	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
217		202
…		…
219	XSLoader::load ("IO::AIO", $VERSION);	204	XSLoader::load ("IO::AIO", $VERSION);
220	}	205	}
221		206
222	=head1 FUNCTIONS	207	=head1 FUNCTIONS
223		208
224	=head2 AIO REQUEST FUNCTIONS	209	=head2 QUICK OVERVIEW
		210
		211	This section simply lists the prototypes most of the functions for
		212	quick reference. See the following sections for function-by-function
		213	documentation.
		214
		215	aio_wd $pathname, $callback->($wd)
		216	aio_open $pathname, $flags, $mode, $callback->($fh)
		217	aio_close $fh, $callback->($status)
		218	aio_seek $fh,$offset,$whence, $callback->($offs)
		219	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		220	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		221	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		222	aio_readahead $fh,$offset,$length, $callback->($retval)
		223	aio_stat $fh_or_path, $callback->($status)
		224	aio_lstat $fh, $callback->($status)
		225	aio_statvfs $fh_or_path, $callback->($statvfs)
		226	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		227	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		228	aio_chmod $fh_or_path, $mode, $callback->($status)
		229	aio_truncate $fh_or_path, $offset, $callback->($status)
		230	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		231	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		232	aio_unlink $pathname, $callback->($status)
		233	aio_mknod $pathname, $mode, $dev, $callback->($status)
		234	aio_link $srcpath, $dstpath, $callback->($status)
		235	aio_symlink $srcpath, $dstpath, $callback->($status)
		236	aio_readlink $pathname, $callback->($link)
		237	aio_realpath $pathname, $callback->($path)
		238	aio_rename $srcpath, $dstpath, $callback->($status)
		239	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		240	aio_mkdir $pathname, $mode, $callback->($status)
		241	aio_rmdir $pathname, $callback->($status)
		242	aio_readdir $pathname, $callback->($entries)
		243	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		244	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		245	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		246	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		247	aio_load $pathname, $data, $callback->($status)
		248	aio_copy $srcpath, $dstpath, $callback->($status)
		249	aio_move $srcpath, $dstpath, $callback->($status)
		250	aio_rmtree $pathname, $callback->($status)
		251	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		252	aio_ioctl $fh, $request, $buf, $callback->($status)
		253	aio_sync $callback->($status)
		254	aio_syncfs $fh, $callback->($status)
		255	aio_fsync $fh, $callback->($status)
		256	aio_fdatasync $fh, $callback->($status)
		257	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		258	aio_pathsync $pathname, $callback->($status)
		259	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
		260	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		261	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		262	aio_mlockall $flags, $callback->($status)
		263	aio_group $callback->(...)
		264	aio_nop $callback->()
		265
		266	$prev_pri = aioreq_pri [$pri]
		267	aioreq_nice $pri_adjust
		268
		269	IO::AIO::poll_wait
		270	IO::AIO::poll_cb
		271	IO::AIO::poll
		272	IO::AIO::flush
		273	IO::AIO::max_poll_reqs $nreqs
		274	IO::AIO::max_poll_time $seconds
		275	IO::AIO::min_parallel $nthreads
		276	IO::AIO::max_parallel $nthreads
		277	IO::AIO::max_idle $nthreads
		278	IO::AIO::idle_timeout $seconds
		279	IO::AIO::max_outstanding $maxreqs
		280	IO::AIO::nreqs
		281	IO::AIO::nready
		282	IO::AIO::npending
		283	IO::AIO::reinit
		284
		285	$nfd = IO::AIO::get_fdlimit [EXPERIMENTAL]
		286	IO::AIO::min_fdlimit $nfd [EXPERIMENTAL]
		287
		288	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		289	IO::AIO::fadvise $fh, $offset, $len, $advice
		290
		291	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		292	IO::AIO::munmap $scalar
		293	IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
		294	IO::AIO::madvise $scalar, $offset, $length, $advice
		295	IO::AIO::mprotect $scalar, $offset, $length, $protect
		296	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		297	IO::AIO::munlockall
		298
		299	# stat extensions
		300	$counter = IO::AIO::st_gen
		301	$seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		302	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		303	$nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		304	$seconds = IO::AIO::st_btimesec
		305	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		306
		307	# very much unportable syscalls
		308	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		309	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		310	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		311	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		312	$fh = IO::AIO::memfd_create $pathname[, $flags]
		313	$fh = IO::AIO::eventfd [$initval, [$flags]]
		314	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		315	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		316	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		317
		318	=head2 API NOTES
225		319
226	All the C<aio_*> calls are more or less thin wrappers around the syscall	320	All the C<aio_*> calls are more or less thin wrappers around the syscall
227	with the same name (sans C<aio_>). The arguments are similar or identical,	321	with the same name (sans C<aio_>). The arguments are similar or identical,
228	and they all accept an additional (and optional) C<$callback> argument	322	and they all accept an additional (and optional) C<$callback> argument
229	which must be a code reference. This code reference will get called with	323	which must be a code reference. This code reference will be called after
230	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	324	the syscall has been executed in an asynchronous fashion. The results
231	perl, which usually delivers "false") as its sole argument after the given	325	of the request will be passed as arguments to the callback (and, if an
232	syscall has been executed asynchronously.	326	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		327	most syscalls return C<-1> on error, unlike perl, which usually delivers
		328	"false").
		329
		330	Some requests (such as C<aio_readdir>) pass the actual results and
		331	communicate failures by passing C<undef>.
233		332
234	All functions expecting a filehandle keep a copy of the filehandle	333	All functions expecting a filehandle keep a copy of the filehandle
235	internally until the request has finished.	334	internally until the request has finished.
236		335
237	All functions return request objects of type L<IO::AIO::REQ> that allow	336	All functions return request objects of type L<IO::AIO::REQ> that allow
238	further manipulation of those requests while they are in-flight.	337	further manipulation of those requests while they are in-flight.
239		338
240	The pathnames you pass to these routines I<must> be absolute and	339	The pathnames you pass to these routines I<should> be absolute. The
241	encoded as octets. The reason for the former is that at the time the	340	reason for this is that at the time the request is being executed, the
242	request is being executed, the current working directory could have	341	current working directory could have changed. Alternatively, you can
243	changed. Alternatively, you can make sure that you never change the	342	make sure that you never change the current working directory anywhere
244	current working directory anywhere in the program and then use relative	343	in the program and then use relative paths. You can also take advantage
245	paths.	344	of IO::AIOs working directory abstraction, that lets you specify paths
		345	relative to some previously-opened "working directory object" - see the
		346	description of the C<IO::AIO::WD> class later in this document.
246		347
247	To encode pathnames as octets, either make sure you either: a) always pass	348	To encode pathnames as octets, either make sure you either: a) always pass
248	in filenames you got from outside (command line, readdir etc.) without	349	in filenames you got from outside (command line, readdir etc.) without
249	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	350	tinkering, b) are in your native filesystem encoding, c) use the Encode
250	your pathnames to the locale (or other) encoding in effect in the user	351	module and encode your pathnames to the locale (or other) encoding in
251	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	352	effect in the user environment, d) use Glib::filename_from_unicode on
252	use something else to ensure your scalar has the correct contents.	353	unicode filenames or e) use something else to ensure your scalar has the
		354	correct contents.
253		355
254	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	356	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
255	handles correctly whether it is set or not.	357	handles correctly whether it is set or not.
		358
		359	=head2 AIO REQUEST FUNCTIONS
256		360
257	=over 4	361	=over 4
258		362
259	=item $prev_pri = aioreq_pri [$pri]	363	=item $prev_pri = aioreq_pri [$pri]
260		364
…		…
290		394
291		395
292	=item aio_open $pathname, $flags, $mode, $callback->($fh)	396	=item aio_open $pathname, $flags, $mode, $callback->($fh)
293		397
294	Asynchronously open or create a file and call the callback with a newly	398	Asynchronously open or create a file and call the callback with a newly
295	created filehandle for the file.	399	created filehandle for the file (or C<undef> in case of an error).
296		400
297	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	401	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
298	for an explanation.	402	for an explanation.
299		403
300	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	404	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
307	by the umask in effect then the request is being executed, so better never	411	by the umask in effect then the request is being executed, so better never
308	change the umask.	412	change the umask.
309		413
310	Example:	414	Example:
311		415
312	aio_open "/etc/passwd", O_RDONLY, 0, sub {	416	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
313	if ($_[0]) {	417	if ($_[0]) {
314	print "open successful, fh is $_[0]\n";	418	print "open successful, fh is $_[0]\n";
315	...	419	...
316	} else {	420	} else {
317	die "open failed: $!\n";	421	die "open failed: $!\n";
318	}	422	}
319	};	423	};
320		424
		425	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		426	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		427	following POSIX and non-POSIX constants are available (missing ones on
		428	your system are, as usual, C<0>):
		429
		430	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		431	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		432	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
		433
321		434
322	=item aio_close $fh, $callback->($status)	435	=item aio_close $fh, $callback->($status)
323		436
324	Asynchronously close a file and call the callback with the result	437	Asynchronously close a file and call the callback with the result
325	code.	438	code.
…		…
334	Or in other words: the file descriptor will be closed, but it will not be	447	Or in other words: the file descriptor will be closed, but it will not be
335	free for reuse until the perl filehandle is closed.	448	free for reuse until the perl filehandle is closed.
336		449
337	=cut	450	=cut
338		451
		452	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		453
		454	Seeks the filehandle to the new C<$offset>, similarly to perl's
		455	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		456	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		457	C<IO::AIO::SEEK_END>).
		458
		459	The resulting absolute offset will be passed to the callback, or C<-1> in
		460	case of an error.
		461
		462	In theory, the C<$whence> constants could be different than the
		463	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		464	so don't panic.
		465
		466	As a GNU/Linux (and maybe Solaris) extension, also the constants
		467	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		468	could be found. No guarantees about suitability for use in C<aio_seek> or
		469	Perl's C<sysseek> can be made though, although I would naively assume they
		470	"just work".
		471
339	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	472	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
340		473
341	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	474	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
342		475
343	Reads or writes C<$length> bytes from or to the specified C<$fh> and	476	Reads or writes C<$length> bytes from or to the specified C<$fh> and
344	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	477	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
345	and calls the callback without the actual number of bytes read (or -1 on	478	calls the callback with the actual number of bytes transferred (or -1 on
346	error, just like the syscall).	479	error, just like the syscall).
347		480
348	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	481	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
349	offset plus the actual number of bytes read.	482	offset plus the actual number of bytes read.
350		483
…		…
375		508
376	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	509	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
377	reading at byte offset C<$in_offset>, and starts writing at the current	510	reading at byte offset C<$in_offset>, and starts writing at the current
378	file offset of C<$out_fh>. Because of that, it is not safe to issue more	511	file offset of C<$out_fh>. Because of that, it is not safe to issue more
379	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	512	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
380	other.	513	other. The same C<$in_fh> works fine though, as this function does not
		514	move or use the file offset of C<$in_fh>.
381		515
		516	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		517	are written, and there is no way to find out how many more bytes have been
		518	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		519	number of bytes written to C<$out_fh>. Only if the result value equals
		520	C<$length> one can assume that C<$length> bytes have been read.
		521
		522	Unlike with other C<aio_> functions, it makes a lot of sense to use
		523	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		524	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		525	the socket I/O will be non-blocking. Note, however, that you can run
		526	into a trap where C<aio_sendfile> reads some data with readahead, then
		527	fails to write all data, and when the socket is ready the next time, the
		528	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		529	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		530	resource usage.
		531
382	This call tries to make use of a native C<sendfile> syscall to provide	532	This call tries to make use of a native C<sendfile>-like syscall to
383	zero-copy operation. For this to work, C<$out_fh> should refer to a	533	provide zero-copy operation. For this to work, C<$out_fh> should refer to
384	socket, and C<$in_fh> should refer to mmap'able file.	534	a socket, and C<$in_fh> should refer to an mmap'able file.
385		535
386	If the native sendfile call fails or is not implemented, it will be	536	If a native sendfile cannot be found or it fails with C<ENOSYS>,
387	emulated, so you can call C<aio_sendfile> on any type of filehandle	537	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		538	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
388	regardless of the limitations of the operating system.	539	type of filehandle regardless of the limitations of the operating system.
389		540
390	Please note, however, that C<aio_sendfile> can read more bytes from	541	As native sendfile syscalls (as practically any non-POSIX interface hacked
391	C<$in_fh> than are written, and there is no way to find out how many	542	together in a hurry to improve benchmark numbers) tend to be rather buggy
392	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	543	on many systems, this implementation tries to work around some known bugs
393	provides the number of bytes written to C<$out_fh>. Only if the result	544	in Linux and FreeBSD kernels (probably others, too), but that might fail,
394	value equals C<$length> one can assume that C<$length> bytes have been	545	so you really really should check the return value of C<aio_sendfile> -
395	read.	546	fewer bytes than expected might have been transferred.
396		547
397		548
398	=item aio_readahead $fh,$offset,$length, $callback->($retval)	549	=item aio_readahead $fh,$offset,$length, $callback->($retval)
399		550
400	C<aio_readahead> populates the page cache with data from a file so that	551	C<aio_readahead> populates the page cache with data from a file so that
…		…
404	whole pages, so that offset is effectively rounded down to a page boundary	555	whole pages, so that offset is effectively rounded down to a page boundary
405	and bytes are read up to the next page boundary greater than or equal to	556	and bytes are read up to the next page boundary greater than or equal to
406	(off-set+length). C<aio_readahead> does not read beyond the end of the	557	(off-set+length). C<aio_readahead> does not read beyond the end of the
407	file. The current file offset of the file is left unchanged.	558	file. The current file offset of the file is left unchanged.
408		559
409	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	560	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
410	emulated by simply reading the data, which would have a similar effect.	561	be emulated by simply reading the data, which would have a similar effect.
411		562
412		563
413	=item aio_stat $fh_or_path, $callback->($status)	564	=item aio_stat $fh_or_path, $callback->($status)
414		565
415	=item aio_lstat $fh, $callback->($status)	566	=item aio_lstat $fh, $callback->($status)
416		567
417	Works like perl's C<stat> or C<lstat> in void context. The callback will	568	Works almost exactly like perl's C<stat> or C<lstat> in void context. The
418	be called after the stat and the results will be available using C<stat _>	569	callback will be called after the stat and the results will be available
419	or C<-s _> etc...	570	using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
		571	and C<-T>).
420		572
421	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,	573	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
422	for an explanation.	574	for an explanation.
423		575
424	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	576	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
425	error when stat'ing a large file, the results will be silently truncated	577	error when stat'ing a large file, the results will be silently truncated
426	unless perl itself is compiled with large file support.	578	unless perl itself is compiled with large file support.
		579
		580	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		581	following constants and functions (if not implemented, the constants will
		582	be C<0> and the functions will either C<croak> or fall back on traditional
		583	behaviour).
		584
		585	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		586	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		587	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		588
		589	To access higher resolution stat timestamps, see L<SUBSECOND STAT TIME
		590	ACCESS>.
427		591
428	Example: Print the length of F</etc/passwd>:	592	Example: Print the length of F</etc/passwd>:
429		593
430	aio_stat "/etc/passwd", sub {	594	aio_stat "/etc/passwd", sub {
431	$_[0] and die "stat failed: $!";	595	$_[0] and die "stat failed: $!";
432	print "size is ", -s _, "\n";	596	print "size is ", -s _, "\n";
433	};	597	};
434		598
435		599
		600	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		601
		602	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		603	whether a file handle or path was passed.
		604
		605	On success, the callback is passed a hash reference with the following
		606	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		607	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		608	is passed.
		609
		610	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		611	C<ST_NOSUID>.
		612
		613	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		614	their correct value when available, or to C<0> on systems that do
		615	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		616	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		617	C<ST_NODIRATIME> and C<ST_RELATIME>.
		618
		619	Example: stat C</wd> and dump out the data if successful.
		620
		621	aio_statvfs "/wd", sub {
		622	my $f = $_[0]
		623	or die "statvfs: $!";
		624
		625	use Data::Dumper;
		626	say Dumper $f;
		627	};
		628
		629	# result:
		630	{
		631	bsize => 1024,
		632	bfree => 4333064312,
		633	blocks => 10253828096,
		634	files => 2050765568,
		635	flag => 4096,
		636	favail => 2042092649,
		637	bavail => 4333064312,
		638	ffree => 2042092649,
		639	namemax => 255,
		640	frsize => 1024,
		641	fsid => 1810
		642	}
		643
436	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	644	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
437		645
438	Works like perl's C<utime> function (including the special case of $atime	646	Works like perl's C<utime> function (including the special case of $atime
439	and $mtime being undef). Fractional times are supported if the underlying	647	and $mtime being undef). Fractional times are supported if the underlying
440	syscalls support them.	648	syscalls support them.
441		649
442	When called with a pathname, uses utimes(2) if available, otherwise	650	When called with a pathname, uses utimensat(2) or utimes(2) if available,
443	utime(2). If called on a file descriptor, uses futimes(2) if available,	651	otherwise utime(2). If called on a file descriptor, uses futimens(2)
444	otherwise returns ENOSYS, so this is not portable.	652	or futimes(2) if available, otherwise returns ENOSYS, so this is not
		653	portable.
445		654
446	Examples:	655	Examples:
447		656
448	# set atime and mtime to current time (basically touch(1)):	657	# set atime and mtime to current time (basically touch(1)):
449	aio_utime "path", undef, undef;	658	aio_utime "path", undef, undef;
…		…
467	=item aio_truncate $fh_or_path, $offset, $callback->($status)	676	=item aio_truncate $fh_or_path, $offset, $callback->($status)
468		677
469	Works like truncate(2) or ftruncate(2).	678	Works like truncate(2) or ftruncate(2).
470		679
471		680
		681	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		682
		683	Allocates or frees disk space according to the C<$mode> argument. See the
		684	linux C<fallocate> documentation for details.
		685
		686	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		687	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		688	to deallocate a file range.
		689
		690	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		691	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		692	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		693	to unshare shared blocks (see your L<fallocate(2)> manpage).
		694
		695	The file system block size used by C<fallocate> is presumably the
		696	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		697	can dictate other limitations.
		698
		699	If C<fallocate> isn't available or cannot be emulated (currently no
		700	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		701
		702
472	=item aio_chmod $fh_or_path, $mode, $callback->($status)	703	=item aio_chmod $fh_or_path, $mode, $callback->($status)
473		704
474	Works like perl's C<chmod> function.	705	Works like perl's C<chmod> function.
475		706
476		707
…		…
478		709
479	Asynchronously unlink (delete) a file and call the callback with the	710	Asynchronously unlink (delete) a file and call the callback with the
480	result code.	711	result code.
481		712
482		713
483	=item aio_mknod $path, $mode, $dev, $callback->($status)	714	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
484		715
485	[EXPERIMENTAL]	716	[EXPERIMENTAL]
486		717
487	Asynchronously create a device node (or fifo). See mknod(2).	718	Asynchronously create a device node (or fifo). See mknod(2).
488		719
489	The only (POSIX-) portable way of calling this function is:	720	The only (POSIX-) portable way of calling this function is:
490		721
491	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	722	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
492		723
		724	See C<aio_stat> for info about some potentially helpful extra constants
		725	and functions.
493		726
494	=item aio_link $srcpath, $dstpath, $callback->($status)	727	=item aio_link $srcpath, $dstpath, $callback->($status)
495		728
496	Asynchronously create a new link to the existing object at C<$srcpath> at	729	Asynchronously create a new link to the existing object at C<$srcpath> at
497	the path C<$dstpath> and call the callback with the result code.	730	the path C<$dstpath> and call the callback with the result code.
…		…
501		734
502	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	735	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
503	the path C<$dstpath> and call the callback with the result code.	736	the path C<$dstpath> and call the callback with the result code.
504		737
505		738
506	=item aio_readlink $path, $callback->($link)	739	=item aio_readlink $pathname, $callback->($link)
507		740
508	Asynchronously read the symlink specified by C<$path> and pass it to	741	Asynchronously read the symlink specified by C<$path> and pass it to
509	the callback. If an error occurs, nothing or undef gets passed to the	742	the callback. If an error occurs, nothing or undef gets passed to the
510	callback.	743	callback.
511		744
512		745
		746	=item aio_realpath $pathname, $callback->($path)
		747
		748	Asynchronously make the path absolute and resolve any symlinks in
		749	C<$path>. The resulting path only consists of directories (same as
		750	L<Cwd::realpath>).
		751
		752	This request can be used to get the absolute path of the current working
		753	directory by passing it a path of F<.> (a single dot).
		754
		755
513	=item aio_rename $srcpath, $dstpath, $callback->($status)	756	=item aio_rename $srcpath, $dstpath, $callback->($status)
514		757
515	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	758	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
516	rename(2) and call the callback with the result code.	759	rename(2) and call the callback with the result code.
		760
		761	On systems that support the AIO::WD working directory abstraction
		762	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		763	of failing, C<rename> is called on the absolute path of C<$wd>.
		764
		765
		766	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		767
		768	Basically a version of C<aio_rename> with an additional C<$flags>
		769	argument. Calling this with C<$flags=0> is the same as calling
		770	C<aio_rename>.
		771
		772	Non-zero flags are currently only supported on GNU/Linux systems that
		773	support renameat2. Other systems fail with C<ENOSYS> in this case.
		774
		775	The following constants are available (missing ones are, as usual C<0>),
		776	see renameat2(2) for details:
		777
		778	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		779	and C<IO::AIO::RENAME_WHITEOUT>.
517		780
518		781
519	=item aio_mkdir $pathname, $mode, $callback->($status)	782	=item aio_mkdir $pathname, $mode, $callback->($status)
520		783
521	Asynchronously mkdir (create) a directory and call the callback with	784	Asynchronously mkdir (create) a directory and call the callback with
…		…
526	=item aio_rmdir $pathname, $callback->($status)	789	=item aio_rmdir $pathname, $callback->($status)
527		790
528	Asynchronously rmdir (delete) a directory and call the callback with the	791	Asynchronously rmdir (delete) a directory and call the callback with the
529	result code.	792	result code.
530		793
		794	On systems that support the AIO::WD working directory abstraction
		795	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		796	C<rmdir> is called on the absolute path of C<$wd>.
		797
531		798
532	=item aio_readdir $pathname, $callback->($entries)	799	=item aio_readdir $pathname, $callback->($entries)
533		800
534	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	801	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
535	directory (i.e. opendir + readdir + closedir). The entries will not be	802	directory (i.e. opendir + readdir + closedir). The entries will not be
536	sorted, and will B<NOT> include the C<.> and C<..> entries.	803	sorted, and will B<NOT> include the C<.> and C<..> entries.
537		804
538	The callback a single argument which is either C<undef> or an array-ref	805	The callback is passed a single argument which is either C<undef> or an
539	with the filenames.	806	array-ref with the filenames.
540		807
541		808
		809	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		810
		811	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
		812	tune behaviour and output format. In case of an error, C<$entries> will be
		813	C<undef>.
		814
		815	The flags are a combination of the following constants, ORed together (the
		816	flags will also be passed to the callback, possibly modified):
		817
		818	=over 4
		819
		820	=item IO::AIO::READDIR_DENTS
		821
		822	Normally the callback gets an arrayref consisting of names only (as
		823	with C<aio_readdir>). If this flag is set, then the callback gets an
		824	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
		825	single directory entry in more detail:
		826
		827	C<$name> is the name of the entry.
		828
		829	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		830
		831	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		832	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		833	C<IO::AIO::DT_WHT>.
		834
		835	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
		836	to know, you have to run stat yourself. Also, for speed/memory reasons,
		837	the C<$type> scalars are read-only: you must not modify them.
		838
		839	C<$inode> is the inode number (which might not be exact on systems with 64
		840	bit inode numbers and 32 bit perls). This field has unspecified content on
		841	systems that do not deliver the inode information.
		842
		843	=item IO::AIO::READDIR_DIRS_FIRST
		844
		845	When this flag is set, then the names will be returned in an order where
		846	likely directories come first, in optimal stat order. This is useful when
		847	you need to quickly find directories, or you want to find all directories
		848	while avoiding to stat() each entry.
		849
		850	If the system returns type information in readdir, then this is used
		851	to find directories directly. Otherwise, likely directories are names
		852	beginning with ".", or otherwise names with no dots, of which names with
		853	short names are tried first.
		854
		855	=item IO::AIO::READDIR_STAT_ORDER
		856
		857	When this flag is set, then the names will be returned in an order
		858	suitable for stat()'ing each one. That is, when you plan to stat() most or
		859	all files in the given directory, then the returned order will likely be
		860	faster.
		861
		862	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
		863	then the likely dirs come first, resulting in a less optimal stat order
		864	for stat'ing all entries, but likely a more optimal order for finding
		865	subdirectories.
		866
		867	=item IO::AIO::READDIR_FOUND_UNKNOWN
		868
		869	This flag should not be set when calling C<aio_readdirx>. Instead, it
		870	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		871	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
		872	C<$type>'s are known, which can be used to speed up some algorithms.
		873
		874	=back
		875
		876
		877	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		878
		879	Opens, reads and closes the given file. The data is put into C<$data>,
		880	which is resized as required.
		881
		882	If C<$offset> is negative, then it is counted from the end of the file.
		883
		884	If C<$length> is zero, then the remaining length of the file is
		885	used. Also, in this case, the same limitations to modifying C<$data> apply
		886	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		887	with C<substr>. If the size of the file is known, specifying a non-zero
		888	C<$length> results in a performance advantage.
		889
		890	This request is similar to the older C<aio_load> request, but since it is
		891	a single request, it might be more efficient to use.
		892
		893	Example: load F</etc/passwd> into C<$passwd>.
		894
		895	my $passwd;
		896	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		897	$_[0] >= 0
		898	or die "/etc/passwd: $!\n";
		899
		900	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		901	print $passwd;
		902	};
		903	IO::AIO::flush;
		904
		905
542	=item aio_load $path, $data, $callback->($status)	906	=item aio_load $pathname, $data, $callback->($status)
543		907
544	This is a composite request that tries to fully load the given file into	908	This is a composite request that tries to fully load the given file into
545	memory. Status is the same as with aio_read.	909	memory. Status is the same as with aio_read.
		910
		911	Using C<aio_slurp> might be more efficient, as it is a single request.
546		912
547	=cut	913	=cut
548		914
549	sub aio_load($$;$) {	915	sub aio_load($$;$) {
550	my ($path, undef, $cb) = @_;	916	my ($path, undef, $cb) = @_;
…		…
569		935
570	=item aio_copy $srcpath, $dstpath, $callback->($status)	936	=item aio_copy $srcpath, $dstpath, $callback->($status)
571		937
572	Try to copy the I<file> (directories not supported as either source or	938	Try to copy the I<file> (directories not supported as either source or
573	destination) from C<$srcpath> to C<$dstpath> and call the callback with	939	destination) from C<$srcpath> to C<$dstpath> and call the callback with
574	the C<0> (error) or C<-1> ok.	940	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		941
		942	Existing destination files will be truncated.
575		943
576	This is a composite request that creates the destination file with	944	This is a composite request that creates the destination file with
577	mode 0200 and copies the contents of the source file into it using	945	mode 0200 and copies the contents of the source file into it using
578	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	946	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
579	uid/gid, in that order.	947	uid/gid, in that order.
…		…
591	my $grp = aio_group $cb;	959	my $grp = aio_group $cb;
592		960
593	aioreq_pri $pri;	961	aioreq_pri $pri;
594	add $grp aio_open $src, O_RDONLY, 0, sub {	962	add $grp aio_open $src, O_RDONLY, 0, sub {
595	if (my $src_fh = $_[0]) {	963	if (my $src_fh = $_[0]) {
596	my @stat = stat $src_fh; # hmm, might bock over nfs?	964	my @stat = stat $src_fh; # hmm, might block over nfs?
597		965
598	aioreq_pri $pri;	966	aioreq_pri $pri;
599	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	967	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
600	if (my $dst_fh = $_[0]) {	968	if (my $dst_fh = $_[0]) {
601	aioreq_pri $pri;	969	aioreq_pri $pri;
…		…
648		1016
649	=item aio_move $srcpath, $dstpath, $callback->($status)	1017	=item aio_move $srcpath, $dstpath, $callback->($status)
650		1018
651	Try to move the I<file> (directories not supported as either source or	1019	Try to move the I<file> (directories not supported as either source or
652	destination) from C<$srcpath> to C<$dstpath> and call the callback with	1020	destination) from C<$srcpath> to C<$dstpath> and call the callback with
653	the C<0> (error) or C<-1> ok.	1021	a status of C<0> (ok) or C<-1> (error, see C<$!>).
654		1022
655	This is a composite request that tries to rename(2) the file first; if	1023	This is a composite request that tries to rename(2) the file first; if
656	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if	1024	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
657	that is successful, unlinks the C<$srcpath>.	1025	that is successful, unlinks the C<$srcpath>.
658		1026
…		…
669	if ($_[0] && $! == EXDEV) {	1037	if ($_[0] && $! == EXDEV) {
670	aioreq_pri $pri;	1038	aioreq_pri $pri;
671	add $grp aio_copy $src, $dst, sub {	1039	add $grp aio_copy $src, $dst, sub {
672	$grp->result ($_[0]);	1040	$grp->result ($_[0]);
673		1041
674	if (!$_[0]) {	1042	unless ($_[0]) {
675	aioreq_pri $pri;	1043	aioreq_pri $pri;
676	add $grp aio_unlink $src;	1044	add $grp aio_unlink $src;
677	}	1045	}
678	};	1046	};
679	} else {	1047	} else {
…		…
682	};	1050	};
683		1051
684	$grp	1052	$grp
685	}	1053	}
686		1054
687	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1055	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
688		1056
689	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1057	Scans a directory (similar to C<aio_readdir>) but additionally tries to
690	efficiently separate the entries of directory C<$path> into two sets of	1058	efficiently separate the entries of directory C<$path> into two sets of
691	names, directories you can recurse into (directories), and ones you cannot	1059	names, directories you can recurse into (directories), and ones you cannot
692	recurse into (everything else, including symlinks to directories).	1060	recurse into (everything else, including symlinks to directories).
693		1061
694	C<aio_scandir> is a composite request that creates of many sub requests_	1062	C<aio_scandir> is a composite request that generates many sub requests.
695	C<$maxreq> specifies the maximum number of outstanding aio requests that	1063	C<$maxreq> specifies the maximum number of outstanding aio requests that
696	this function generates. If it is C<< <= 0 >>, then a suitable default	1064	this function generates. If it is C<< <= 0 >>, then a suitable default
697	will be chosen (currently 4).	1065	will be chosen (currently 4).
698		1066
699	On error, the callback is called without arguments, otherwise it receives	1067	On error, the callback is called without arguments, otherwise it receives
…		…
709		1077
710	Implementation notes.	1078	Implementation notes.
711		1079
712	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	1080	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
713		1081
		1082	If readdir returns file type information, then this is used directly to
		1083	find directories.
		1084
714	After reading the directory, the modification time, size etc. of the	1085	Otherwise, after reading the directory, the modification time, size etc.
715	directory before and after the readdir is checked, and if they match (and	1086	of the directory before and after the readdir is checked, and if they
716	isn't the current time), the link count will be used to decide how many	1087	match (and isn't the current time), the link count will be used to decide
717	entries are directories (if >= 2). Otherwise, no knowledge of the number	1088	how many entries are directories (if >= 2). Otherwise, no knowledge of the
718	of subdirectories will be assumed.	1089	number of subdirectories will be assumed.
719		1090
720	Then entries will be sorted into likely directories (everything without	1091	Then entries will be sorted into likely directories a non-initial dot
721	a non-initial dot currently) and likely non-directories (everything	1092	currently) and likely non-directories (see C<aio_readdirx>). Then every
722	else). Then every entry plus an appended C</.> will be C<stat>'ed,	1093	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
723	likely directories first. If that succeeds, it assumes that the entry	1094	in order of their inode numbers. If that succeeds, it assumes that the
724	is a directory or a symlink to directory (which will be checked	1095	entry is a directory or a symlink to directory (which will be checked
725	seperately). This is often faster than stat'ing the entry itself because	1096	separately). This is often faster than stat'ing the entry itself because
726	filesystems might detect the type of the entry without reading the inode	1097	filesystems might detect the type of the entry without reading the inode
727	data (e.g. ext2fs filetype feature).	1098	data (e.g. ext2fs filetype feature), even on systems that cannot return
		1099	the filetype information on readdir.
728		1100
729	If the known number of directories (link count - 2) has been reached, the	1101	If the known number of directories (link count - 2) has been reached, the
730	rest of the entries is assumed to be non-directories.	1102	rest of the entries is assumed to be non-directories.
731		1103
732	This only works with certainty on POSIX (= UNIX) filesystems, which	1104	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
745		1117
746	my $grp = aio_group $cb;	1118	my $grp = aio_group $cb;
747		1119
748	$maxreq = 4 if $maxreq <= 0;	1120	$maxreq = 4 if $maxreq <= 0;
749		1121
750	# stat once	1122	# get a wd object
751	aioreq_pri $pri;	1123	aioreq_pri $pri;
752	add $grp aio_stat $path, sub {	1124	add $grp aio_wd $path, sub {
		1125	$_[0]
753	return $grp->result () if $_[0];	1126	or return $grp->result ();
754	my $now = time;
755	my $hash1 = join ":", (stat _)[0,1,3,7,9];
756		1127
757	# read the directory entries	1128	my $wd = [shift, "."];
		1129
		1130	# stat once
758	aioreq_pri $pri;	1131	aioreq_pri $pri;
759	add $grp aio_readdir $path, sub {	1132	add $grp aio_stat $wd, sub {
760	my $entries = shift
761	or return $grp->result ();	1133	return $grp->result () if $_[0];
		1134	my $now = time;
		1135	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		1136	my $rdxflags = READDIR_DIRS_FIRST;
762		1137
763	# stat the dir another time	1138	if ((stat _)[3] < 2) {
		1139	# at least one non-POSIX filesystem exists
		1140	# that returns useful DT_type values: btrfs,
		1141	# so optimise for this here by requesting dents
		1142	$rdxflags |= READDIR_DENTS;
		1143	}
		1144
		1145	# read the directory entries
764	aioreq_pri $pri;	1146	aioreq_pri $pri;
765	add $grp aio_stat $path, sub {	1147	add $grp aio_readdirx $wd, $rdxflags, sub {
766	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1148	my ($entries, $flags) = @_
		1149	or return $grp->result ();
767		1150
		1151	if ($rdxflags & READDIR_DENTS) {
		1152	# if we requested type values, see if we can use them directly.
		1153
		1154	# if there were any DT_UNKNOWN entries then we assume we
		1155	# don't know. alternatively, we could assume that if we get
		1156	# one DT_DIR, then all directories are indeed marked with
		1157	# DT_DIR, but this seems not required for btrfs, and this
		1158	# is basically the "btrfs can't get it's act together" code
		1159	# branch.
		1160	unless ($flags & READDIR_FOUND_UNKNOWN) {
		1161	# now we have valid DT_ information for all entries,
		1162	# so use it as an optimisation without further stat's.
		1163	# they must also all be at the beginning of @$entries
		1164	# by now.
		1165
768	my $ndirs;	1166	my $dirs;
769		1167
770	# take the slow route if anything looks fishy
771	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
772	$ndirs = -1;
773	} else {
774	# if nlink == 2, we are finished
775	# on non-posix-fs's, we rely on nlink < 2
776	$ndirs = (stat _)[3] - 2
777	or return $grp->result ([], $entries);
778	}
779
780	# sort into likely dirs and likely nondirs
781	# dirs == files without ".", short entries first
782	$entries = [map $_->[0],
783	sort { $b->[1] cmp $a->[1] }
784	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
785	@$entries];
786
787	my (@dirs, @nondirs);
788
789	my $statgrp = add $grp aio_group sub {
790	$grp->result (\@dirs, \@nondirs);
791	};
792
793	limit $statgrp $maxreq;
794	feed $statgrp sub {
795	return unless @$entries;
796	my $entry = pop @$entries;
797
798	aioreq_pri $pri;
799	add $statgrp aio_stat "$path/$entry/.", sub {
800	if ($_[0] < 0) {	1168	if (@$entries) {
801	push @nondirs, $entry;	1169	for (0 .. $#$entries) {
802	} else {	1170	if ($entries->[$_][1] != DT_DIR) {
803	# need to check for real directory	1171	# splice out directories
804	aioreq_pri $pri;	1172	$dirs = [splice @$entries, 0, $_];
805	add $statgrp aio_lstat "$path/$entry", sub {
806	if (-d _) {
807	push @dirs, $entry;
808
809	unless (--$ndirs) {
810	push @nondirs, @$entries;
811	feed $statgrp;
812	}	1173	last;
813	} else {
814	push @nondirs, $entry;
815	}	1174	}
816	}	1175	}
		1176
		1177	# if we didn't find any non-dir, then all entries are dirs
		1178	unless ($dirs) {
		1179	($dirs, $entries) = ($entries, []);
		1180	}
		1181	} else {
		1182	# directory is empty, so there are no sbdirs
		1183	$dirs = [];
817	}	1184	}
		1185
		1186	# either splice'd the directories out or the dir was empty.
		1187	# convert dents to filenames
		1188	$_ = $_->[0] for @$dirs;
		1189	$_ = $_->[0] for @$entries;
		1190
		1191	return $grp->result ($dirs, $entries);
		1192	}
		1193
		1194	# cannot use, so return to our old ways
		1195	# by pretending we only scanned for names.
		1196	$_ = $_->[0] for @$entries;
		1197	}
		1198
		1199	# stat the dir another time
		1200	aioreq_pri $pri;
		1201	add $grp aio_stat $wd, sub {
		1202	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		1203
		1204	my $ndirs;
		1205
		1206	# take the slow route if anything looks fishy
		1207	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
		1208	$ndirs = -1;
		1209	} else {
		1210	# if nlink == 2, we are finished
		1211	# for non-posix-fs's, we rely on nlink < 2
		1212	$ndirs = (stat _)[3] - 2
		1213	or return $grp->result ([], $entries);
		1214	}
		1215
		1216	my (@dirs, @nondirs);
		1217
		1218	my $statgrp = add $grp aio_group sub {
		1219	$grp->result (\@dirs, \@nondirs);
		1220	};
		1221
		1222	limit $statgrp $maxreq;
		1223	feed $statgrp sub {
		1224	return unless @$entries;
		1225	my $entry = shift @$entries;
		1226
		1227	aioreq_pri $pri;
		1228	$wd->[1] = "$entry/.";
		1229	add $statgrp aio_stat $wd, sub {
		1230	if ($_[0] < 0) {
		1231	push @nondirs, $entry;
		1232	} else {
		1233	# need to check for real directory
		1234	aioreq_pri $pri;
		1235	$wd->[1] = $entry;
		1236	add $statgrp aio_lstat $wd, sub {
		1237	if (-d _) {
		1238	push @dirs, $entry;
		1239
		1240	unless (--$ndirs) {
		1241	push @nondirs, @$entries;
		1242	feed $statgrp;
		1243	}
		1244	} else {
		1245	push @nondirs, $entry;
		1246	}
		1247	}
		1248	}
		1249	};
818	};	1250	};
819	};	1251	};
820	};	1252	};
821	};	1253	};
822	};	1254	};
823		1255
824	$grp	1256	$grp
825	}	1257	}
826		1258
827	=item aio_rmtree $path, $callback->($status)	1259	=item aio_rmtree $pathname, $callback->($status)
828		1260
829	Delete a directory tree starting (and including) C<$path>, return the	1261	Delete a directory tree starting (and including) C<$path>, return the
830	status of the final C<rmdir> only. This is a composite request that	1262	status of the final C<rmdir> only. This is a composite request that
831	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1263	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
832	everything else.	1264	everything else.
833		1265
834	=cut	1266	=cut
835		1267
…		…
857	};	1289	};
858		1290
859	$grp	1291	$grp
860	}	1292	}
861		1293
		1294	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1295
		1296	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1297
		1298	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1299	they execute asynchronously and pass the return value to the callback.
		1300
		1301	Both calls can be used for a lot of things, some of which make more sense
		1302	to run asynchronously in their own thread, while some others make less
		1303	sense. For example, calls that block waiting for external events, such
		1304	as locking, will also lock down an I/O thread while it is waiting, which
		1305	can deadlock the whole I/O system. At the same time, there might be no
		1306	alternative to using a thread to wait.
		1307
		1308	So in general, you should only use these calls for things that do
		1309	(filesystem) I/O, not for things that wait for other events (network,
		1310	other processes), although if you are careful and know what you are doing,
		1311	you still can.
		1312
		1313	The following constants are available and can be used for normal C<ioctl>
		1314	and C<fcntl> as well (missing ones are, as usual C<0>):
		1315
		1316	C<F_DUPFD_CLOEXEC>,
		1317
		1318	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1319
		1320	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1321
		1322	C<F_ADD_SEALS>, C<F_GET_SEALS>, C<F_SEAL_SEAL>, C<F_SEAL_SHRINK>, C<F_SEAL_GROW> and
		1323	C<F_SEAL_WRITE>.
		1324
		1325	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1326	C<FS_IOC_FIEMAP>.
		1327
		1328	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1329	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1330
		1331	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1332	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1333	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1334	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1335	C<FS_FL_USER_MODIFIABLE>.
		1336
		1337	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1338	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1339	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1340	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1341
862	=item aio_sync $callback->($status)	1342	=item aio_sync $callback->($status)
863		1343
864	Asynchronously call sync and call the callback when finished.	1344	Asynchronously call sync and call the callback when finished.
865		1345
866	=item aio_fsync $fh, $callback->($status)	1346	=item aio_fsync $fh, $callback->($status)
…		…
873	Asynchronously call fdatasync on the given filehandle and call the	1353	Asynchronously call fdatasync on the given filehandle and call the
874	callback with the fdatasync result code.	1354	callback with the fdatasync result code.
875		1355
876	If this call isn't available because your OS lacks it or it couldn't be	1356	If this call isn't available because your OS lacks it or it couldn't be
877	detected, it will be emulated by calling C<fsync> instead.	1357	detected, it will be emulated by calling C<fsync> instead.
		1358
		1359	=item aio_syncfs $fh, $callback->($status)
		1360
		1361	Asynchronously call the syncfs syscall to sync the filesystem associated
		1362	to the given filehandle and call the callback with the syncfs result
		1363	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1364	errno to C<ENOSYS> nevertheless.
878		1365
879	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1366	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
880		1367
881	Sync the data portion of the file specified by C<$offset> and C<$length>	1368	Sync the data portion of the file specified by C<$offset> and C<$length>
882	to disk (but NOT the metadata), by calling the Linux-specific	1369	to disk (but NOT the metadata), by calling the Linux-specific
…		…
886	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1373	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
887	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1374	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
888	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1375	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
889	manpage for details.	1376	manpage for details.
890		1377
891	=item aio_pathsync $path, $callback->($status)	1378	=item aio_pathsync $pathname, $callback->($status)
892		1379
893	This request tries to open, fsync and close the given path. This is a	1380	This request tries to open, fsync and close the given path. This is a
894	composite request intended to sync directories after directory operations	1381	composite request intended to sync directories after directory operations
895	(E.g. rename). This might not work on all operating systems or have any	1382	(E.g. rename). This might not work on all operating systems or have any
896	specific effect, but usually it makes sure that directory changes get	1383	specific effect, but usually it makes sure that directory changes get
897	written to disc. It works for anything that can be opened for read-only,	1384	written to disc. It works for anything that can be opened for read-only,
898	not just directories.	1385	not just directories.
		1386
		1387	Future versions of this function might fall back to other methods when
		1388	C<fsync> on the directory fails (such as calling C<sync>).
899		1389
900	Passes C<0> when everything went ok, and C<-1> on error.	1390	Passes C<0> when everything went ok, and C<-1> on error.
901		1391
902	=cut	1392	=cut
903		1393
…		…
924	};	1414	};
925		1415
926	$grp	1416	$grp
927	}	1417	}
928		1418
		1419	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
		1420
		1421	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1422	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1423	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1424	scalar must only be modified in-place while an aio operation is pending on
		1425	it).
		1426
		1427	It calls the C<msync> function of your OS, if available, with the memory
		1428	area starting at C<$offset> in the string and ending C<$length> bytes
		1429	later. If C<$length> is negative, counts from the end, and if C<$length>
		1430	is C<undef>, then it goes till the end of the string. The flags can be
		1431	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
		1432	C<IO::AIO::MS_INVALIDATE>.
		1433
		1434	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1435
		1436	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1437	scalars.
		1438
		1439	It touches (reads or writes) all memory pages in the specified
		1440	range inside the scalar. All caveats and parameters are the same
		1441	as for C<aio_msync>, above, except for flags, which must be either
		1442	C<0> (which reads all pages and ensures they are instantiated) or
		1443	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
		1444	writing an octet from it, which dirties the page).
		1445
		1446	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1447
		1448	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1449	scalars.
		1450
		1451	It reads in all the pages of the underlying storage into memory (if any)
		1452	and locks them, so they are not getting swapped/paged out or removed.
		1453
		1454	If C<$length> is undefined, then the scalar will be locked till the end.
		1455
		1456	On systems that do not implement C<mlock>, this function returns C<-1>
		1457	and sets errno to C<ENOSYS>.
		1458
		1459	Note that the corresponding C<munlock> is synchronous and is
		1460	documented under L<MISCELLANEOUS FUNCTIONS>.
		1461
		1462	Example: open a file, mmap and mlock it - both will be undone when
		1463	C<$data> gets destroyed.
		1464
		1465	open my $fh, "<", $path or die "$path: $!";
		1466	my $data;
		1467	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1468	aio_mlock $data; # mlock in background
		1469
		1470	=item aio_mlockall $flags, $callback->($status)
		1471
		1472	Calls the C<mlockall> function with the given C<$flags> (a
		1473	combination of C<IO::AIO::MCL_CURRENT>, C<IO::AIO::MCL_FUTURE> and
		1474	C<IO::AIO::MCL_ONFAULT>).
		1475
		1476	On systems that do not implement C<mlockall>, this function returns C<-1>
		1477	and sets errno to C<ENOSYS>. Similarly, flag combinations not supported
		1478	by the system result in a return value of C<-1> with errno being set to
		1479	C<EINVAL>.
		1480
		1481	Note that the corresponding C<munlockall> is synchronous and is
		1482	documented under L<MISCELLANEOUS FUNCTIONS>.
		1483
		1484	Example: asynchronously lock all current and future pages into memory.
		1485
		1486	aio_mlockall IO::AIO::MCL_FUTURE;
		1487
		1488	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1489
		1490	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1491	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1492	the ioctl is not available on your OS, then this request will fail with
		1493	C<ENOSYS>.
		1494
		1495	C<$start> is the starting offset to query extents for, C<$length> is the
		1496	size of the range to query - if it is C<undef>, then the whole file will
		1497	be queried.
		1498
		1499	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1500	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1501	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1502	the data portion.
		1503
		1504	C<$count> is the maximum number of extent records to return. If it is
		1505	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1506	case, if it is C<0>, then the callback receives the number of extents
		1507	instead of the extents themselves (which is unreliable, see below).
		1508
		1509	If an error occurs, the callback receives no arguments. The special
		1510	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1511
		1512	Otherwise, the callback receives an array reference with extent
		1513	structures. Each extent structure is an array reference itself, with the
		1514	following members:
		1515
		1516	[$logical, $physical, $length, $flags]
		1517
		1518	Flags is any combination of the following flag values (typically either C<0>
		1519	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1520
		1521	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1522	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1523	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1524	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1525	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1526	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1527
		1528	At the time of this writing (Linux 3.2), this request is unreliable unless
		1529	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1530	it to return all extents of a range for files with a large number of
		1531	extents. The code (only) works around all these issues if C<$count> is
		1532	C<undef>.
		1533
929	=item aio_group $callback->(...)	1534	=item aio_group $callback->(...)
930		1535
931	This is a very special aio request: Instead of doing something, it is a	1536	This is a very special aio request: Instead of doing something, it is a
932	container for other aio requests, which is useful if you want to bundle	1537	container for other aio requests, which is useful if you want to bundle
933	many requests into a single, composite, request with a definite callback	1538	many requests into a single, composite, request with a definite callback
…		…
970	immense (it blocks a thread for a long time) so do not use this function	1575	immense (it blocks a thread for a long time) so do not use this function
971	except to put your application under artificial I/O pressure.	1576	except to put your application under artificial I/O pressure.
972		1577
973	=back	1578	=back
974		1579
		1580
		1581	=head2 IO::AIO::WD - multiple working directories
		1582
		1583	Your process only has one current working directory, which is used by all
		1584	threads. This makes it hard to use relative paths (some other component
		1585	could call C<chdir> at any time, and it is hard to control when the path
		1586	will be used by IO::AIO).
		1587
		1588	One solution for this is to always use absolute paths. This usually works,
		1589	but can be quite slow (the kernel has to walk the whole path on every
		1590	access), and can also be a hassle to implement.
		1591
		1592	Newer POSIX systems have a number of functions (openat, fdopendir,
		1593	futimensat and so on) that make it possible to specify working directories
		1594	per operation.
		1595
		1596	For portability, and because the clowns who "designed", or shall I write,
		1597	perpetrated this new interface were obviously half-drunk, this abstraction
		1598	cannot be perfect, though.
		1599
		1600	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1601	object. This object stores the canonicalised, absolute version of the
		1602	path, and on systems that allow it, also a directory file descriptor.
		1603
		1604	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1605	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1606	object and a pathname instead (or the IO::AIO::WD object alone, which
		1607	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1608	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1609	to that IO::AIO::WD object.
		1610
		1611	For example, to get a wd object for F</etc> and then stat F<passwd>
		1612	inside, you would write:
		1613
		1614	aio_wd "/etc", sub {
		1615	my $etcdir = shift;
		1616
		1617	# although $etcdir can be undef on error, there is generally no reason
		1618	# to check for errors here, as aio_stat will fail with ENOENT
		1619	# when $etcdir is undef.
		1620
		1621	aio_stat [$etcdir, "passwd"], sub {
		1622	# yay
		1623	};
		1624	};
		1625
		1626	The fact that C<aio_wd> is a request and not a normal function shows that
		1627	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1628	which is why it is done asynchronously.
		1629
		1630	To stat the directory obtained with C<aio_wd> above, one could write
		1631	either of the following three request calls:
		1632
		1633	aio_lstat "/etc" , sub { ... # pathname as normal string
		1634	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1635	aio_lstat $wd , sub { ... # shorthand for the previous
		1636
		1637	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1638	object and the pathname string, so you could write the following without
		1639	causing any issues due to C<$path> getting reused:
		1640
		1641	my $path = [$wd, undef];
		1642
		1643	for my $name (qw(abc def ghi)) {
		1644	$path->[1] = $name;
		1645	aio_stat $path, sub {
		1646	# ...
		1647	};
		1648	}
		1649
		1650	There are some caveats: when directories get renamed (or deleted), the
		1651	pathname string doesn't change, so will point to the new directory (or
		1652	nowhere at all), while the directory fd, if available on the system,
		1653	will still point to the original directory. Most functions accepting a
		1654	pathname will use the directory fd on newer systems, and the string on
		1655	older systems. Some functions (such as C<aio_realpath>) will always rely on
		1656	the string form of the pathname.
		1657
		1658	So this functionality is mainly useful to get some protection against
		1659	C<chdir>, to easily get an absolute path out of a relative path for future
		1660	reference, and to speed up doing many operations in the same directory
		1661	(e.g. when stat'ing all files in a directory).
		1662
		1663	The following functions implement this working directory abstraction:
		1664
		1665	=over 4
		1666
		1667	=item aio_wd $pathname, $callback->($wd)
		1668
		1669	Asynchonously canonicalise the given pathname and convert it to an
		1670	IO::AIO::WD object representing it. If possible and supported on the
		1671	system, also open a directory fd to speed up pathname resolution relative
		1672	to this working directory.
		1673
		1674	If something goes wrong, then C<undef> is passwd to the callback instead
		1675	of a working directory object and C<$!> is set appropriately. Since
		1676	passing C<undef> as working directory component of a pathname fails the
		1677	request with C<ENOENT>, there is often no need for error checking in the
		1678	C<aio_wd> callback, as future requests using the value will fail in the
		1679	expected way.
		1680
		1681	=item IO::AIO::CWD
		1682
		1683	This is a compiletime constant (object) that represents the process
		1684	current working directory.
		1685
		1686	Specifying this object as working directory object for a pathname is as if
		1687	the pathname would be specified directly, without a directory object. For
		1688	example, these calls are functionally identical:
		1689
		1690	aio_stat "somefile", sub { ... };
		1691	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1692
		1693	=back
		1694
		1695	To recover the path associated with an IO::AIO::WD object, you can use
		1696	C<aio_realpath>:
		1697
		1698	aio_realpath $wd, sub {
		1699	warn "path is $_[0]\n";
		1700	};
		1701
		1702	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1703	sometimes, fall back to using an absolue path.
		1704
975	=head2 IO::AIO::REQ CLASS	1705	=head2 IO::AIO::REQ CLASS
976		1706
977	All non-aggregate C<aio_*> functions return an object of this class when	1707	All non-aggregate C<aio_*> functions return an object of this class when
978	called in non-void context.	1708	called in non-void context.
979		1709
…		…
982	=item cancel $req	1712	=item cancel $req
983		1713
984	Cancels the request, if possible. Has the effect of skipping execution	1714	Cancels the request, if possible. Has the effect of skipping execution
985	when entering the B<execute> state and skipping calling the callback when	1715	when entering the B<execute> state and skipping calling the callback when
986	entering the the B<result> state, but will leave the request otherwise	1716	entering the the B<result> state, but will leave the request otherwise
987	untouched. That means that requests that currently execute will not be	1717	untouched (with the exception of readdir). That means that requests that
988	stopped and resources held by the request will not be freed prematurely.	1718	currently execute will not be stopped and resources held by the request
		1719	will not be freed prematurely.
989		1720
990	=item cb $req $callback->(...)	1721	=item cb $req $callback->(...)
991		1722
992	Replace (or simply set) the callback registered to the request.	1723	Replace (or simply set) the callback registered to the request.
993		1724
…		…
1067	=item $grp->cancel_subs	1798	=item $grp->cancel_subs
1068		1799
1069	Cancel all subrequests and clears any feeder, but not the group request	1800	Cancel all subrequests and clears any feeder, but not the group request
1070	itself. Useful when you queued a lot of events but got a result early.	1801	itself. Useful when you queued a lot of events but got a result early.
1071		1802
		1803	The group request will finish normally (you cannot add requests to the
		1804	group).
		1805
1072	=item $grp->result (...)	1806	=item $grp->result (...)
1073		1807
1074	Set the result value(s) that will be passed to the group callback when all	1808	Set the result value(s) that will be passed to the group callback when all
1075	subrequests have finished and set the groups errno to the current value	1809	subrequests have finished and set the groups errno to the current value
1076	of errno (just like calling C<errno> without an error number). By default,	1810	of errno (just like calling C<errno> without an error number). By default,
…		…
1092		1826
1093	Sets a feeder/generator on this group: every group can have an attached	1827	Sets a feeder/generator on this group: every group can have an attached
1094	generator that generates requests if idle. The idea behind this is that,	1828	generator that generates requests if idle. The idea behind this is that,
1095	although you could just queue as many requests as you want in a group,	1829	although you could just queue as many requests as you want in a group,
1096	this might starve other requests for a potentially long time. For example,	1830	this might starve other requests for a potentially long time. For example,
1097	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1831	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1098	delaying any later requests for a long time.	1832	requests, delaying any later requests for a long time.
1099		1833
1100	To avoid this, and allow incremental generation of requests, you can	1834	To avoid this, and allow incremental generation of requests, you can
1101	instead a group and set a feeder on it that generates those requests. The	1835	instead a group and set a feeder on it that generates those requests. The
1102	feed callback will be called whenever there are few enough (see C<limit>,	1836	feed callback will be called whenever there are few enough (see C<limit>,
1103	below) requests active in the group itself and is expected to queue more	1837	below) requests active in the group itself and is expected to queue more
…		…
1135	The default value for the limit is C<0>, but note that setting a feeder	1869	The default value for the limit is C<0>, but note that setting a feeder
1136	automatically bumps it up to C<2>.	1870	automatically bumps it up to C<2>.
1137		1871
1138	=back	1872	=back
1139		1873
		1874
1140	=head2 SUPPORT FUNCTIONS	1875	=head2 SUPPORT FUNCTIONS
1141		1876
1142	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1877	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1143		1878
1144	=over 4	1879	=over 4
1145		1880
1146	=item $fileno = IO::AIO::poll_fileno	1881	=item $fileno = IO::AIO::poll_fileno
1147		1882
1148	Return the I<request result pipe file descriptor>. This filehandle must be	1883	Return the I<request result pipe file descriptor>. This filehandle must be
1149	polled for reading by some mechanism outside this module (e.g. Event or	1884	polled for reading by some mechanism outside this module (e.g. EV, Glib,
1150	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1885	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1151	to call C<poll_cb> to check the results.	1886	you have to call C<poll_cb> to check the results.
1152		1887
1153	See C<poll_cb> for an example.	1888	See C<poll_cb> for an example.
1154		1889
1155	=item IO::AIO::poll_cb	1890	=item IO::AIO::poll_cb
1156		1891
1157	Process some outstanding events on the result pipe. You have to call this	1892	Process some requests that have reached the result phase (i.e. they have
1158	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1893	been executed but the results are not yet reported). You have to call
1159	returned earlier for whatever reason. Returns immediately when no events	1894	this "regularly" to finish outstanding requests.
1160	are outstanding. The amount of events processed depends on the settings of
1161	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1162		1895
		1896	Returns C<0> if all events could be processed (or there were no
		1897	events to process), or C<-1> if it returned earlier for whatever
		1898	reason. Returns immediately when no events are outstanding. The amount
		1899	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
		1900	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
		1901
1163	If not all requests were processed for whatever reason, the filehandle	1902	If not all requests were processed for whatever reason, the poll file
1164	will still be ready when C<poll_cb> returns, so normally you don't have to	1903	descriptor will still be ready when C<poll_cb> returns, so normally you
1165	do anything special to have it called later.	1904	don't have to do anything special to have it called later.
		1905
		1906	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1907	ready, it can be beneficial to call this function from loops which submit
		1908	a lot of requests, to make sure the results get processed when they become
		1909	available and not just when the loop is finished and the event loop takes
		1910	over again. This function returns very fast when there are no outstanding
		1911	requests.
1166		1912
1167	Example: Install an Event watcher that automatically calls	1913	Example: Install an Event watcher that automatically calls
1168	IO::AIO::poll_cb with high priority:	1914	IO::AIO::poll_cb with high priority (more examples can be found in the
		1915	SYNOPSIS section, at the top of this document):
1169		1916
1170	Event->io (fd => IO::AIO::poll_fileno,	1917	Event->io (fd => IO::AIO::poll_fileno,
1171	poll => 'r', async => 1,	1918	poll => 'r', async => 1,
1172	cb => \&IO::AIO::poll_cb);	1919	cb => \&IO::AIO::poll_cb);
		1920
		1921	=item IO::AIO::poll_wait
		1922
		1923	Wait until either at least one request is in the result phase or no
		1924	requests are outstanding anymore.
		1925
		1926	This is useful if you want to synchronously wait for some requests to
		1927	become ready, without actually handling them.
		1928
		1929	See C<nreqs> for an example.
		1930
		1931	=item IO::AIO::poll
		1932
		1933	Waits until some requests have been handled.
		1934
		1935	Returns the number of requests processed, but is otherwise strictly
		1936	equivalent to:
		1937
		1938	IO::AIO::poll_wait, IO::AIO::poll_cb
		1939
		1940	=item IO::AIO::flush
		1941
		1942	Wait till all outstanding AIO requests have been handled.
		1943
		1944	Strictly equivalent to:
		1945
		1946	IO::AIO::poll_wait, IO::AIO::poll_cb
		1947	while IO::AIO::nreqs;
		1948
		1949	This function can be useful at program aborts, to make sure outstanding
		1950	I/O has been done (C<IO::AIO> uses an C<END> block which already calls
		1951	this function on normal exits), or when you are merely using C<IO::AIO>
		1952	for its more advanced functions, rather than for async I/O, e.g.:
		1953
		1954	my ($dirs, $nondirs);
		1955	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1956	IO::AIO::flush;
		1957	# $dirs, $nondirs are now set
1173		1958
1174	=item IO::AIO::max_poll_reqs $nreqs	1959	=item IO::AIO::max_poll_reqs $nreqs
1175		1960
1176	=item IO::AIO::max_poll_time $seconds	1961	=item IO::AIO::max_poll_time $seconds
1177		1962
…		…
1202	# use a low priority so other tasks have priority	1987	# use a low priority so other tasks have priority
1203	Event->io (fd => IO::AIO::poll_fileno,	1988	Event->io (fd => IO::AIO::poll_fileno,
1204	poll => 'r', nice => 1,	1989	poll => 'r', nice => 1,
1205	cb => &IO::AIO::poll_cb);	1990	cb => &IO::AIO::poll_cb);
1206		1991
1207	=item IO::AIO::poll_wait
1208
1209	If there are any outstanding requests and none of them in the result
1210	phase, wait till the result filehandle becomes ready for reading (simply
1211	does a C<select> on the filehandle. This is useful if you want to
1212	synchronously wait for some requests to finish).
1213
1214	See C<nreqs> for an example.
1215
1216	=item IO::AIO::poll
1217
1218	Waits until some requests have been handled.
1219
1220	Returns the number of requests processed, but is otherwise strictly
1221	equivalent to:
1222
1223	IO::AIO::poll_wait, IO::AIO::poll_cb
1224
1225	=item IO::AIO::flush
1226
1227	Wait till all outstanding AIO requests have been handled.
1228
1229	Strictly equivalent to:
1230
1231	IO::AIO::poll_wait, IO::AIO::poll_cb
1232	while IO::AIO::nreqs;
1233
1234	=back	1992	=back
		1993
1235		1994
1236	=head3 CONTROLLING THE NUMBER OF THREADS	1995	=head3 CONTROLLING THE NUMBER OF THREADS
1237		1996
1238	=over	1997	=over
1239		1998
…		…
1271		2030
1272	Under normal circumstances you don't need to call this function.	2031	Under normal circumstances you don't need to call this function.
1273		2032
1274	=item IO::AIO::max_idle $nthreads	2033	=item IO::AIO::max_idle $nthreads
1275		2034
1276	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	2035	Limit the number of threads (default: 4) that are allowed to idle
1277	threads that did not get a request to process within 10 seconds). That	2036	(i.e., threads that did not get a request to process within the idle
1278	means if a thread becomes idle while C<$nthreads> other threads are also	2037	timeout (default: 10 seconds). That means if a thread becomes idle while
1279	idle, it will free its resources and exit.	2038	C<$nthreads> other threads are also idle, it will free its resources and
		2039	exit.
1280		2040
1281	This is useful when you allow a large number of threads (e.g. 100 or 1000)	2041	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1282	to allow for extremely high load situations, but want to free resources	2042	to allow for extremely high load situations, but want to free resources
1283	under normal circumstances (1000 threads can easily consume 30MB of RAM).	2043	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1284		2044
1285	The default is probably ok in most situations, especially if thread	2045	The default is probably ok in most situations, especially if thread
1286	creation is fast. If thread creation is very slow on your system you might	2046	creation is fast. If thread creation is very slow on your system you might
1287	want to use larger values.	2047	want to use larger values.
1288		2048
		2049	=item IO::AIO::idle_timeout $seconds
		2050
		2051	Sets the minimum idle timeout (default 10) after which worker threads are
		2052	allowed to exit. SEe C<IO::AIO::max_idle>.
		2053
1289	=item IO::AIO::max_outstanding $maxreqs	2054	=item IO::AIO::max_outstanding $maxreqs
		2055
		2056	Sets the maximum number of outstanding requests to C<$nreqs>. If
		2057	you do queue up more than this number of requests, the next call to
		2058	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		2059	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		2060	longer exceeded.
		2061
		2062	In other words, this setting does not enforce a queue limit, but can be
		2063	used to make poll functions block if the limit is exceeded.
1290		2064
1291	This is a very bad function to use in interactive programs because it	2065	This is a very bad function to use in interactive programs because it
1292	blocks, and a bad way to reduce concurrency because it is inexact: Better	2066	blocks, and a bad way to reduce concurrency because it is inexact: Better
1293	use an C<aio_group> together with a feed callback.	2067	use an C<aio_group> together with a feed callback.
1294		2068
1295	Sets the maximum number of outstanding requests to C<$nreqs>. If you	2069	Its main use is in scripts without an event loop - when you want to stat
1296	do queue up more than this number of requests, the next call to the	2070	a lot of files, you can write something like this:
1297	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1298	function will block until the limit is no longer exceeded.
1299		2071
1300	The default value is very large, so there is no practical limit on the	2072	IO::AIO::max_outstanding 32;
1301	number of outstanding requests.
1302		2073
1303	You can still queue as many requests as you want. Therefore,	2074	for my $path (...) {
1304	C<max_outstanding> is mainly useful in simple scripts (with low values) or	2075	aio_stat $path , ...;
1305	as a stop gap to shield against fatal memory overflow (with large values).	2076	IO::AIO::poll_cb;
		2077	}
		2078
		2079	IO::AIO::flush;
		2080
		2081	The call to C<poll_cb> inside the loop will normally return instantly, but
		2082	as soon as more thna C<32> reqeusts are in-flight, it will block until
		2083	some requests have been handled. This keeps the loop from pushing a large
		2084	number of C<aio_stat> requests onto the queue.
		2085
		2086	The default value for C<max_outstanding> is very large, so there is no
		2087	practical limit on the number of outstanding requests.
1306		2088
1307	=back	2089	=back
		2090
1308		2091
1309	=head3 STATISTICAL INFORMATION	2092	=head3 STATISTICAL INFORMATION
1310		2093
1311	=over	2094	=over
1312		2095
…		…
1330	Returns the number of requests currently in the pending state (executed,	2113	Returns the number of requests currently in the pending state (executed,
1331	but not yet processed by poll_cb).	2114	but not yet processed by poll_cb).
1332		2115
1333	=back	2116	=back
1334		2117
		2118
		2119	=head3 SUBSECOND STAT TIME ACCESS
		2120
		2121	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2122	generally find access/modification and change times with subsecond time
		2123	accuracy of the system supports it, but perl's built-in functions only
		2124	return the integer part.
		2125
		2126	The following functions return the timestamps of the most recent
		2127	stat with subsecond precision on most systems and work both after
		2128	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2129	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2130	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2131
		2132	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2133	full resolution without rounding and work with standard perl C<stat>,
		2134	alleviating the need to call the special C<Time::HiRes> functions, which
		2135	do not act like their perl counterparts.
		2136
		2137	On operating systems or file systems where subsecond time resolution is
		2138	not supported or could not be detected, a fractional part of C<0> is
		2139	returned, so it is always safe to call these functions.
		2140
		2141	=over 4
		2142
		2143	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		2144
		2145	Return the access, modication, change or birth time, respectively,
		2146	including fractional part. Due to the limited precision of floating point,
		2147	the accuracy on most platforms is only a bit better than milliseconds
		2148	for times around now - see the I<nsec> function family, below, for full
		2149	accuracy.
		2150
		2151	File birth time is only available when the OS and perl support it (on
		2152	FreeBSD and NetBSD at the time of this writing, although support is
		2153	adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
		2154	it). On systems where it isn't available, C<0> is currently returned, but
		2155	this might change to C<undef> in a future version.
		2156
		2157	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		2158
		2159	Returns access, modification, change and birth time all in one go, and
		2160	maybe more times in the future version.
		2161
		2162	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		2163
		2164	Return the fractional access, modifcation, change or birth time, in nanoseconds,
		2165	as an integer in the range C<0> to C<999999999>.
		2166
		2167	Note that no accessors are provided for access, modification and
		2168	change times - you need to get those from C<stat _> if required (C<int
		2169	IO::AIO::st_atime> and so on will I<not> generally give you the correct
		2170	value).
		2171
		2172	=item $seconds = IO::AIO::st_btimesec
		2173
		2174	The (integral) seconds part of the file birth time, if available.
		2175
		2176	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		2177
		2178	Like the functions above, but returns all four times in one go (and maybe
		2179	more in future versions).
		2180
		2181	=item $counter = IO::AIO::st_gen
		2182
		2183	Returns the generation counter (in practice this is just a random number)
		2184	of the file. This is only available on platforms which have this member in
		2185	their C<struct stat> (most BSDs at the time of this writing) and generally
		2186	only to the root usert. If unsupported, C<0> is returned, but this might
		2187	change to C<undef> in a future version.
		2188
		2189	=back
		2190
		2191	Example: print the high resolution modification time of F</etc>, using
		2192	C<stat>, and C<IO::AIO::aio_stat>.
		2193
		2194	if (stat "/etc") {
		2195	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2196	}
		2197
		2198	IO::AIO::aio_stat "/etc", sub {
		2199	$_[0]
		2200	and return;
		2201
		2202	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2203	};
		2204
		2205	IO::AIO::flush;
		2206
		2207	Output of the awbove on my system, showing reduced and full accuracy:
		2208
		2209	stat(/etc) mtime: 1534043702.020808
		2210	aio_stat(/etc) mtime: 1534043702.020807792
		2211
		2212
		2213	=head3 MISCELLANEOUS FUNCTIONS
		2214
		2215	IO::AIO implements some functions that are useful when you want to use
		2216	some "Advanced I/O" function not available to in Perl, without going the
		2217	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2218	counterpart.
		2219
		2220	=over 4
		2221
		2222	=item $numfd = IO::AIO::get_fdlimit
		2223
		2224	This function is I<EXPERIMENTAL> and subject to change.
		2225
		2226	Tries to find the current file descriptor limit and returns it, or
		2227	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2228	the highest valid file descriptor number.
		2229
		2230	=item IO::AIO::min_fdlimit [$numfd]
		2231
		2232	This function is I<EXPERIMENTAL> and subject to change.
		2233
		2234	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2235	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2236	is missing, it will try to set a very high limit, although this is not
		2237	recommended when you know the actual minimum that you require.
		2238
		2239	If the limit cannot be raised enough, the function makes a best-effort
		2240	attempt to increase the limit as much as possible, using various
		2241	tricks, while still failing. You can query the resulting limit using
		2242	C<IO::AIO::get_fdlimit>.
		2243
		2244	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2245	true.
		2246
		2247	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		2248
		2249	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		2250	but is blocking (this makes most sense if you know the input data is
		2251	likely cached already and the output filehandle is set to non-blocking
		2252	operations).
		2253
		2254	Returns the number of bytes copied, or C<-1> on error.
		2255
		2256	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		2257
		2258	Simply calls the C<posix_fadvise> function (see its
		2259	manpage for details). The following advice constants are
		2260	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		2261	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		2262	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		2263
		2264	On systems that do not implement C<posix_fadvise>, this function returns
		2265	ENOSYS, otherwise the return value of C<posix_fadvise>.
		2266
		2267	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		2268
		2269	Simply calls the C<posix_madvise> function (see its
		2270	manpage for details). The following advice constants are
		2271	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		2272	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2273	C<IO::AIO::MADV_DONTNEED>.
		2274
		2275	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2276	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2277	will be reduced to fit into the C<$scalar>.
		2278
		2279	On systems that do not implement C<posix_madvise>, this function returns
		2280	ENOSYS, otherwise the return value of C<posix_madvise>.
		2281
		2282	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		2283
		2284	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		2285	$scalar (see its manpage for details). The following protect
		2286	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		2287	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2288
		2289	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2290	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2291	will be reduced to fit into the C<$scalar>.
		2292
		2293	On systems that do not implement C<mprotect>, this function returns
		2294	ENOSYS, otherwise the return value of C<mprotect>.
		2295
		2296	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		2297
		2298	Memory-maps a file (or anonymous memory range) and attaches it to the
		2299	given C<$scalar>, which will act like a string scalar. Returns true on
		2300	success, and false otherwise.
		2301
		2302	The scalar must exist, but its contents do not matter - this means you
		2303	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2304	the scalar first.
		2305
		2306	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
		2307	which don't change the string length, and most read-only operations such
		2308	as copying it or searching it with regexes and so on.
		2309
		2310	Anything else is unsafe and will, at best, result in memory leaks.
		2311
		2312	The memory map associated with the C<$scalar> is automatically removed
		2313	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
		2314	or C<IO::AIO::munmap> functions are called on it.
		2315
		2316	This calls the C<mmap>(2) function internally. See your system's manual
		2317	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		2318
		2319	The C<$length> must be larger than zero and smaller than the actual
		2320	filesize.
		2321
		2322	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		2323	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		2324
		2325	C<$flags> can be a combination of
		2326	C<IO::AIO::MAP_SHARED> or
		2327	C<IO::AIO::MAP_PRIVATE>,
		2328	or a number of system-specific flags (when not available, the are C<0>):
		2329	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
		2330	C<IO::AIO::MAP_LOCKED>,
		2331	C<IO::AIO::MAP_NORESERVE>,
		2332	C<IO::AIO::MAP_POPULATE>,
		2333	C<IO::AIO::MAP_NONBLOCK>,
		2334	C<IO::AIO::MAP_FIXED>,
		2335	C<IO::AIO::MAP_GROWSDOWN>,
		2336	C<IO::AIO::MAP_32BIT>,
		2337	C<IO::AIO::MAP_HUGETLB> or
		2338	C<IO::AIO::MAP_STACK>.
		2339
		2340	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		2341
		2342	C<$offset> is the offset from the start of the file - it generally must be
		2343	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		2344
		2345	Example:
		2346
		2347	use Digest::MD5;
		2348	use IO::AIO;
		2349
		2350	open my $fh, "<verybigfile"
		2351	or die "$!";
		2352
		2353	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		2354	or die "verybigfile: $!";
		2355
		2356	my $fast_md5 = md5 $data;
		2357
		2358	=item IO::AIO::munmap $scalar
		2359
		2360	Removes a previous mmap and undefines the C<$scalar>.
		2361
		2362	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2363
		2364	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2365	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2366	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2367
		2368	Returns true if successful, and false otherwise. If the underlying mmapped
		2369	region has changed address, then the true value has the numerical value
		2370	C<1>, otherwise it has the numerical value C<0>:
		2371
		2372	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2373	or die "mremap: $!";
		2374
		2375	if ($success*1) {
		2376	warn "scalar has chanegd address in memory\n";
		2377	}
		2378
		2379	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2380	implemented, but not supported and might go away in a future version.
		2381
		2382	On systems where this call is not supported or is not emulated, this call
		2383	returns falls and sets C<$!> to C<ENOSYS>.
		2384
		2385	=item IO::AIO::mlockall $flags
		2386
		2387	Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
		2388	but is blocking.
		2389
		2390	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		2391
		2392	Calls the C<munlock> function, undoing the effects of a previous
		2393	C<aio_mlock> call (see its description for details).
		2394
		2395	=item IO::AIO::munlockall
		2396
		2397	Calls the C<munlockall> function.
		2398
		2399	On systems that do not implement C<munlockall>, this function returns
		2400	ENOSYS, otherwise the return value of C<munlockall>.
		2401
		2402	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2403
		2404	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2405	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2406	should be the file offset.
		2407
		2408	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2409	silently corrupt the data in this case.
		2410
		2411	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2412	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2413	C<IO::AIO::SPLICE_F_GIFT>.
		2414
		2415	See the C<splice(2)> manpage for details.
		2416
		2417	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2418
		2419	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2420	description for C<IO::AIO::splice> above for details.
		2421
		2422	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2423
		2424	Attempts to query or change the pipe buffer size. Obviously works only
		2425	on pipes, and currently works only on GNU/Linux systems, and fails with
		2426	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2427	size on other systems, drop me a note.
		2428
		2429	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2430
		2431	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2432	C<$flags> is missing or C<0>, then this should be the same as a call to
		2433	perl's built-in C<pipe> function and create a new pipe, and works on
		2434	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2435	(..., 4096, O_BINARY)>.
		2436
		2437	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2438	the given flags (Linux 2.6.27, glibc 2.9).
		2439
		2440	On success, the read and write file handles are returned.
		2441
		2442	On error, nothing will be returned. If the pipe2 syscall is missing and
		2443	C<$flags> is non-zero, fails with C<ENOSYS>.
		2444
		2445	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2446	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2447	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2448
		2449	Example: create a pipe race-free w.r.t. threads and fork:
		2450
		2451	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2452	or die "pipe2: $!\n";
		2453
		2454	=item $fh = IO::AIO::memfd_create $pathname[, $flags]
		2455
		2456	This is a direct interface to the Linux L<memfd_create(2)> system
		2457	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2458	should be C<IO::AIO::MFD_CLOEXEC>.
		2459
		2460	On success, the new memfd filehandle is returned, otherwise returns
		2461	C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
		2462
		2463	Please refer to L<memfd_create(2)> for more info on this call.
		2464
		2465	The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
		2466	C<IO::AIO::MFD_ALLOW_SEALING> and C<IO::AIO::MFD_HUGETLB>.
		2467
		2468	Example: create a new memfd.
		2469
		2470	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2471	or die "m,emfd_create: $!\n";
		2472	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2473
		2474	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2475	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2476
		2477	On success, the new eventfd filehandle is returned, otherwise returns
		2478	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2479
		2480	Please refer to L<eventfd(2)> for more info on this call.
		2481
		2482	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2483	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2484
		2485	Example: create a new eventfd filehandle:
		2486
		2487	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2488	or die "eventfd: $!\n";
		2489
		2490	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2491
		2492	This is a direct interface to the Linux L<timerfd_create(2)> system
		2493	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2494	should be C<IO::AIO::TFD_CLOEXEC>.
		2495
		2496	On success, the new timerfd filehandle is returned, otherwise returns
		2497	C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
		2498
		2499	Please refer to L<timerfd_create(2)> for more info on this call.
		2500
		2501	The following C<$clockid> values are
		2502	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2503	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2504	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2505	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2506
		2507	The following C<$flags> values are available (Linux
		2508	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2509
		2510	Example: create a new timerfd and set it to one-second repeated alarms,
		2511	then wait for two alarms:
		2512
		2513	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2514	or die "timerfd_create: $!\n";
		2515
		2516	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2517	or die "timerfd_settime: $!\n";
		2518
		2519	for (1..2) {
		2520	8 == sysread $fh, my $buf, 8
		2521	or die "timerfd read failure\n";
		2522
		2523	printf "number of expirations (likely 1): %d\n",
		2524	unpack "Q", $buf;
		2525	}
		2526
		2527	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2528
		2529	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2530	call. Please refer to its manpage for more info on this call.
		2531
		2532	The new itimerspec is specified using two (possibly fractional) second
		2533	values, C<$new_interval> and C<$new_value>).
		2534
		2535	On success, the current interval and value are returned (as per
		2536	C<timerfd_gettime>). On failure, the empty list is returned.
		2537
		2538	The following C<$flags> values are
		2539	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2540	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2541
		2542	See C<IO::AIO::timerfd_create> for a full example.
		2543
		2544	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2545
		2546	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2547	call. Please refer to its manpage for more info on this call.
		2548
		2549	On success, returns the current values of interval and value for the given
		2550	timerfd (as potentially fractional second values). On failure, the empty
		2551	list is returned.
		2552
		2553	=back
		2554
1335	=cut	2555	=cut
1336		2556
1337	min_parallel 8;	2557	min_parallel 8;
1338		2558
1339	END { flush }	2559	END { flush }
1340		2560
1341	1;	2561	1;
1342		2562
		2563	=head1 EVENT LOOP INTEGRATION
		2564
		2565	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		2566	automatically into many event loops:
		2567
		2568	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		2569	use AnyEvent::AIO;
		2570
		2571	You can also integrate IO::AIO manually into many event loops, here are
		2572	some examples of how to do this:
		2573
		2574	# EV integration
		2575	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		2576
		2577	# Event integration
		2578	Event->io (fd => IO::AIO::poll_fileno,
		2579	poll => 'r',
		2580	cb => \&IO::AIO::poll_cb);
		2581
		2582	# Glib/Gtk2 integration
		2583	add_watch Glib::IO IO::AIO::poll_fileno,
		2584	in => sub { IO::AIO::poll_cb; 1 };
		2585
		2586	# Tk integration
		2587	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		2588	readable => \&IO::AIO::poll_cb);
		2589
		2590	# Danga::Socket integration
		2591	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		2592	\&IO::AIO::poll_cb);
		2593
1343	=head2 FORK BEHAVIOUR	2594	=head2 FORK BEHAVIOUR
1344		2595
1345	This module should do "the right thing" when the process using it forks:	2596	Usage of pthreads in a program changes the semantics of fork
		2597	considerably. Specifically, only async-safe functions can be called after
		2598	fork. Perl doesn't know about this, so in general, you cannot call fork
		2599	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2600	pthreads, so this applies, but many other extensions and (for inexplicable
		2601	reasons) perl itself often is linked against pthreads, so this limitation
		2602	applies to quite a lot of perls.
1346		2603
1347	Before the fork, IO::AIO enters a quiescent state where no requests	2604	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1348	can be added in other threads and no results will be processed. After	2605	only works in the process that loaded it. Forking is fully supported, but
1349	the fork the parent simply leaves the quiescent state and continues	2606	using IO::AIO in the child is not.
1350	request/result processing, while the child frees the request/result queue
1351	(so that the requests started before the fork will only be handled in the
1352	parent). Threads will be started on demand until the limit set in the
1353	parent process has been reached again.
1354		2607
1355	In short: the parent will, after a short pause, continue as if fork had	2608	You might get around by not I<using> IO::AIO before (or after)
1356	not been called, while the child will act as if IO::AIO has not been used	2609	forking. You could also try to call the L<IO::AIO::reinit> function in the
1357	yet.	2610	child:
		2611
		2612	=over 4
		2613
		2614	=item IO::AIO::reinit
		2615
		2616	Abandons all current requests and I/O threads and simply reinitialises all
		2617	data structures. This is not an operation supported by any standards, but
		2618	happens to work on GNU/Linux and some newer BSD systems.
		2619
		2620	The only reasonable use for this function is to call it after forking, if
		2621	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2622	the process will result in undefined behaviour. Calling it at any time
		2623	will also result in any undefined (by POSIX) behaviour.
		2624
		2625	=back
		2626
		2627	=head2 LINUX-SPECIFIC CALLS
		2628
		2629	When a call is documented as "linux-specific" then this means it
		2630	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2631	availability and compatibility of such calls regardless of the platform
		2632	it is compiled on, so platforms such as FreeBSD which often implement
		2633	these calls will work. When in doubt, call them and see if they fail wth
		2634	C<ENOSYS>.
1358		2635
1359	=head2 MEMORY USAGE	2636	=head2 MEMORY USAGE
1360		2637
1361	Per-request usage:	2638	Per-request usage:
1362		2639
…		…
1375	temporary buffers, and each thread requires a stack and other data	2652	temporary buffers, and each thread requires a stack and other data
1376	structures (usually around 16k-128k, depending on the OS).	2653	structures (usually around 16k-128k, depending on the OS).
1377		2654
1378	=head1 KNOWN BUGS	2655	=head1 KNOWN BUGS
1379		2656
1380	Known bugs will be fixed in the next release.	2657	Known bugs will be fixed in the next release :)
		2658
		2659	=head1 KNOWN ISSUES
		2660
		2661	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2662	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2663	non-created hash slots or other scalars I didn't think of. It's best to
		2664	avoid such and either use scalar variables or making sure that the scalar
		2665	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2666
		2667	I am not sure anything can be done about this, so this is considered a
		2668	known issue, rather than a bug.
1381		2669
1382	=head1 SEE ALSO	2670	=head1 SEE ALSO
1383		2671
1384	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2672	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1385	more natural syntax.	2673	more natural syntax and L<IO::FDPass> for file descriptor passing.
1386		2674
1387	=head1 AUTHOR	2675	=head1 AUTHOR
1388		2676
1389	Marc Lehmann <schmorp@schmorp.de>	2677	Marc Lehmann <schmorp@schmorp.de>
1390	http://home.schmorp.de/	2678	http://home.schmorp.de/

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