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Revision 1.171 by root, Sat Jan 2 14:24:32 2010 UTC vs.
Revision 1.312 by root, Tue Jul 27 18:46:06 2021 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
…		…
25	my $req = aio_unlink "/tmp/file", sub { };	25	my $req = aio_unlink "/tmp/file", sub { };
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
31	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
32	use AnyEvent::AIO;
33
34	# EV integration
35	my $aio_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		30
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. It is implemented as an interface to C<libeio>	34	operating system supports. It is implemented as an interface to C<libeio>
…		…
81	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
82	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
83	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
84	using threads anyway.	61	using threads anyway.
85		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
86	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,
87	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
88	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
89	call C<poll_cb> (or other C<aio_> functions) recursively.	70	call C<poll_cb> (or other C<aio_> functions) recursively.
90		71
91	=head2 EXAMPLE	72	=head2 EXAMPLE
92		73
93	This is a simple example that uses the EV module and loads	74	This is a simple example that uses the EV module and loads
94	F</etc/passwd> asynchronously:	75	F</etc/passwd> asynchronously:
95		76
96	use Fcntl;
97	use EV;	77	use EV;
98	use IO::AIO;	78	use IO::AIO;
99		79
100	# register the IO::AIO callback with EV	80	# register the IO::AIO callback with EV
101	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	81	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
102		82
103	# queue the request to open /etc/passwd	83	# queue the request to open /etc/passwd
104	aio_open "/etc/passwd", O_RDONLY, 0, sub {	84	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
105	my $fh = shift	85	my $fh = shift
106	or die "error while opening: $!";	86	or die "error while opening: $!";
107		87
108	# stat'ing filehandles is generally non-blocking	88	# stat'ing filehandles is generally non-blocking
109	my $size = -s $fh;	89	my $size = -s $fh;
…		…
118		98
119	# file contents now in $contents	99	# file contents now in $contents
120	print $contents;	100	print $contents;
121		101
122	# exit event loop and program	102	# exit event loop and program
123	EV::unloop;	103	EV::break;
124	};	104	};
125	};	105	};
126		106
127	# possibly queue up other requests, or open GUI windows,	107	# possibly queue up other requests, or open GUI windows,
128	# check for sockets etc. etc.	108	# check for sockets etc. etc.
129		109
130	# process events as long as there are some:	110	# process events as long as there are some:
131	EV::loop;	111	EV::run;
132		112
133	=head1 REQUEST ANATOMY AND LIFETIME	113	=head1 REQUEST ANATOMY AND LIFETIME
134		114
135	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
136	directly visible to Perl.	116	directly visible to Perl.
…		…
191	use common::sense;	171	use common::sense;
192		172
193	use base 'Exporter';	173	use base 'Exporter';
194		174
195	BEGIN {	175	BEGIN {
196	our $VERSION = '3.4';	176	our $VERSION = 4.76;
197		177
198	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
199	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx	179	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
200	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
201	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
202	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
203	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
204	aio_chmod aio_utime aio_truncate	185	aio_chmod aio_utime aio_truncate
205	aio_msync aio_mtouch);	186	aio_msync aio_mtouch aio_mlock aio_mlockall
		187	aio_statvfs
		188	aio_slurp
		189	aio_wd);
206		190
207	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	191	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
208	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	192	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
209	min_parallel max_parallel max_idle	193	min_parallel max_parallel max_idle idle_timeout
210	nreqs nready npending nthreads	194	nreqs nready npending nthreads
211	max_poll_time max_poll_reqs	195	max_poll_time max_poll_reqs
212	sendfile fadvise);	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
		286	IO::AIO::min_fdlimit $nfd
		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::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
		309	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		310	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		311	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		312	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		313	$fh = IO::AIO::memfd_create $pathname[, $flags]
		314	$fh = IO::AIO::eventfd [$initval, [$flags]]
		315	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		316	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		317	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		318
		319	=head2 API NOTES
225		320
226	All the C<aio_*> calls are more or less thin wrappers around the syscall	321	All the C<aio_*> calls are more or less thin wrappers around the syscall
227	with the same name (sans C<aio_>). The arguments are similar or identical,	322	with the same name (sans C<aio_>). The arguments are similar or identical,
228	and they all accept an additional (and optional) C<$callback> argument	323	and they all accept an additional (and optional) C<$callback> argument
229	which must be a code reference. This code reference will get called with	324	which must be a code reference. This code reference will be called after
230	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	325	the syscall has been executed in an asynchronous fashion. The results
231	perl, which usually delivers "false") as its sole argument after the given	326	of the request will be passed as arguments to the callback (and, if an
232	syscall has been executed asynchronously.	327	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		328	most syscalls return C<-1> on error, unlike perl, which usually delivers
		329	"false").
		330
		331	Some requests (such as C<aio_readdir>) pass the actual results and
		332	communicate failures by passing C<undef>.
233		333
234	All functions expecting a filehandle keep a copy of the filehandle	334	All functions expecting a filehandle keep a copy of the filehandle
235	internally until the request has finished.	335	internally until the request has finished.
236		336
237	All functions return request objects of type L<IO::AIO::REQ> that allow	337	All functions return request objects of type L<IO::AIO::REQ> that allow
238	further manipulation of those requests while they are in-flight.	338	further manipulation of those requests while they are in-flight.
239		339
240	The pathnames you pass to these routines I<must> be absolute and	340	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	341	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	342	current working directory could have changed. Alternatively, you can
243	changed. Alternatively, you can make sure that you never change the	343	make sure that you never change the current working directory anywhere
244	current working directory anywhere in the program and then use relative	344	in the program and then use relative paths. You can also take advantage
245	paths.	345	of IO::AIOs working directory abstraction, that lets you specify paths
		346	relative to some previously-opened "working directory object" - see the
		347	description of the C<IO::AIO::WD> class later in this document.
246		348
247	To encode pathnames as octets, either make sure you either: a) always pass	349	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	350	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	351	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	352	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)	353	effect in the user environment, d) use Glib::filename_from_unicode on
252	use something else to ensure your scalar has the correct contents.	354	unicode filenames or e) use something else to ensure your scalar has the
		355	correct contents.
253		356
254	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	357	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
255	handles correctly whether it is set or not.	358	handles correctly whether it is set or not.
		359
		360	=head2 AIO REQUEST FUNCTIONS
256		361
257	=over 4	362	=over 4
258		363
259	=item $prev_pri = aioreq_pri [$pri]	364	=item $prev_pri = aioreq_pri [$pri]
260		365
…		…
290		395
291		396
292	=item aio_open $pathname, $flags, $mode, $callback->($fh)	397	=item aio_open $pathname, $flags, $mode, $callback->($fh)
293		398
294	Asynchronously open or create a file and call the callback with a newly	399	Asynchronously open or create a file and call the callback with a newly
295	created filehandle for the file.	400	created filehandle for the file (or C<undef> in case of an error).
296		401
297	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	402	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
298	for an explanation.	403	for an explanation.
299		404
300	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	405	The C<$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	412	by the umask in effect then the request is being executed, so better never
308	change the umask.	413	change the umask.
309		414
310	Example:	415	Example:
311		416
312	aio_open "/etc/passwd", O_RDONLY, 0, sub {	417	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
313	if ($_[0]) {	418	if ($_[0]) {
314	print "open successful, fh is $_[0]\n";	419	print "open successful, fh is $_[0]\n";
315	...	420	...
316	} else {	421	} else {
317	die "open failed: $!\n";	422	die "open failed: $!\n";
318	}	423	}
319	};	424	};
320		425
		426	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		427	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		428	following POSIX and non-POSIX constants are available (missing ones on
		429	your system are, as usual, C<0>):
		430
		431	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		432	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		433	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
		434
321		435
322	=item aio_close $fh, $callback->($status)	436	=item aio_close $fh, $callback->($status)
323		437
324	Asynchronously close a file and call the callback with the result	438	Asynchronously close a file and call the callback with the result
325	code.	439	code.
…		…
334	Or in other words: the file descriptor will be closed, but it will not be	448	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.	449	free for reuse until the perl filehandle is closed.
336		450
337	=cut	451	=cut
338		452
		453	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		454
		455	Seeks the filehandle to the new C<$offset>, similarly to perl's
		456	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		457	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		458	C<IO::AIO::SEEK_END>).
		459
		460	The resulting absolute offset will be passed to the callback, or C<-1> in
		461	case of an error.
		462
		463	In theory, the C<$whence> constants could be different than the
		464	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		465	so don't panic.
		466
		467	As a GNU/Linux (and maybe Solaris) extension, also the constants
		468	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		469	could be found. No guarantees about suitability for use in C<aio_seek> or
		470	Perl's C<sysseek> can be made though, although I would naively assume they
		471	"just work".
		472
339	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	473	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
340		474
341	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	475	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
342		476
343	Reads or writes C<$length> bytes from or to the specified C<$fh> and	477	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<$dataoffset>	478	C<$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	479	calls the callback with the actual number of bytes transferred (or -1 on
346	error, just like the syscall).	480	error, just like the syscall).
347		481
348	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	482	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
349	offset plus the actual number of bytes read.	483	offset plus the actual number of bytes read.
350		484
…		…
375		509
376	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	510	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
377	reading at byte offset C<$in_offset>, and starts writing at the current	511	reading at byte offset C<$in_offset>, and starts writing at the current
378	file offset of C<$out_fh>. Because of that, it is not safe to issue more	512	file offset of C<$out_fh>. Because of that, it is not safe to issue more
379	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	513	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
380	other.	514	other. The same C<$in_fh> works fine though, as this function does not
		515	move or use the file offset of C<$in_fh>.
381		516
		517	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		518	are written, and there is no way to find out how many more bytes have been
		519	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		520	number of bytes written to C<$out_fh>. Only if the result value equals
		521	C<$length> one can assume that C<$length> bytes have been read.
		522
		523	Unlike with other C<aio_> functions, it makes a lot of sense to use
		524	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		525	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		526	the socket I/O will be non-blocking. Note, however, that you can run
		527	into a trap where C<aio_sendfile> reads some data with readahead, then
		528	fails to write all data, and when the socket is ready the next time, the
		529	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		530	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		531	resource usage.
		532
382	This call tries to make use of a native C<sendfile> syscall to provide	533	This call tries to make use of a native C<sendfile>-like syscall to
383	zero-copy operation. For this to work, C<$out_fh> should refer to a	534	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.	535	a socket, and C<$in_fh> should refer to an mmap'able file.
385		536
386	If a native sendfile cannot be found or it fails with C<ENOSYS>,	537	If a native sendfile cannot be found or it fails with C<ENOSYS>,
387	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,	538	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
388	it will be emulated, so you can call C<aio_sendfile> on any type of	539	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
389	filehandle regardless of the limitations of the operating system.	540	type of filehandle regardless of the limitations of the operating system.
390		541
391	Please note, however, that C<aio_sendfile> can read more bytes from	542	As native sendfile syscalls (as practically any non-POSIX interface hacked
392	C<$in_fh> than are written, and there is no way to find out how many	543	together in a hurry to improve benchmark numbers) tend to be rather buggy
393	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	544	on many systems, this implementation tries to work around some known bugs
394	provides the number of bytes written to C<$out_fh>. Only if the result	545	in Linux and FreeBSD kernels (probably others, too), but that might fail,
395	value equals C<$length> one can assume that C<$length> bytes have been	546	so you really really should check the return value of C<aio_sendfile> -
396	read.	547	fewer bytes than expected might have been transferred.
397		548
398		549
399	=item aio_readahead $fh,$offset,$length, $callback->($retval)	550	=item aio_readahead $fh,$offset,$length, $callback->($retval)
400		551
401	C<aio_readahead> populates the page cache with data from a file so that	552	C<aio_readahead> populates the page cache with data from a file so that
…		…
405	whole pages, so that offset is effectively rounded down to a page boundary	556	whole pages, so that offset is effectively rounded down to a page boundary
406	and bytes are read up to the next page boundary greater than or equal to	557	and bytes are read up to the next page boundary greater than or equal to
407	(off-set+length). C<aio_readahead> does not read beyond the end of the	558	(off-set+length). C<aio_readahead> does not read beyond the end of the
408	file. The current file offset of the file is left unchanged.	559	file. The current file offset of the file is left unchanged.
409		560
410	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	561	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
411	emulated by simply reading the data, which would have a similar effect.	562	be emulated by simply reading the data, which would have a similar effect.
412		563
413		564
414	=item aio_stat $fh_or_path, $callback->($status)	565	=item aio_stat $fh_or_path, $callback->($status)
415		566
416	=item aio_lstat $fh, $callback->($status)	567	=item aio_lstat $fh, $callback->($status)
417		568
418	Works like perl's C<stat> or C<lstat> in void context. The callback will	569	Works almost exactly like perl's C<stat> or C<lstat> in void context. The
419	be called after the stat and the results will be available using C<stat _>	570	callback will be called after the stat and the results will be available
420	or C<-s _> etc...	571	using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
		572	and C<-T>).
421		573
422	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,	574	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
423	for an explanation.	575	for an explanation.
424		576
425	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	577	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
426	error when stat'ing a large file, the results will be silently truncated	578	error when stat'ing a large file, the results will be silently truncated
427	unless perl itself is compiled with large file support.	579	unless perl itself is compiled with large file support.
		580
		581	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		582	following constants and functions (if not implemented, the constants will
		583	be C<0> and the functions will either C<croak> or fall back on traditional
		584	behaviour).
		585
		586	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		587	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		588	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		589
		590	To access higher resolution stat timestamps, see L<SUBSECOND STAT TIME
		591	ACCESS>.
428		592
429	Example: Print the length of F</etc/passwd>:	593	Example: Print the length of F</etc/passwd>:
430		594
431	aio_stat "/etc/passwd", sub {	595	aio_stat "/etc/passwd", sub {
432	$_[0] and die "stat failed: $!";	596	$_[0] and die "stat failed: $!";
433	print "size is ", -s _, "\n";	597	print "size is ", -s _, "\n";
434	};	598	};
435		599
436		600
		601	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		602
		603	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		604	whether a file handle or path was passed.
		605
		606	On success, the callback is passed a hash reference with the following
		607	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		608	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		609	is passed.
		610
		611	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		612	C<ST_NOSUID>.
		613
		614	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		615	their correct value when available, or to C<0> on systems that do
		616	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		617	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		618	C<ST_NODIRATIME> and C<ST_RELATIME>.
		619
		620	Example: stat C</wd> and dump out the data if successful.
		621
		622	aio_statvfs "/wd", sub {
		623	my $f = $_[0]
		624	or die "statvfs: $!";
		625
		626	use Data::Dumper;
		627	say Dumper $f;
		628	};
		629
		630	# result:
		631	{
		632	bsize => 1024,
		633	bfree => 4333064312,
		634	blocks => 10253828096,
		635	files => 2050765568,
		636	flag => 4096,
		637	favail => 2042092649,
		638	bavail => 4333064312,
		639	ffree => 2042092649,
		640	namemax => 255,
		641	frsize => 1024,
		642	fsid => 1810
		643	}
		644
437	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	645	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
438		646
439	Works like perl's C<utime> function (including the special case of $atime	647	Works like perl's C<utime> function (including the special case of $atime
440	and $mtime being undef). Fractional times are supported if the underlying	648	and $mtime being undef). Fractional times are supported if the underlying
441	syscalls support them.	649	syscalls support them.
442		650
443	When called with a pathname, uses utimes(2) if available, otherwise	651	When called with a pathname, uses utimensat(2) or utimes(2) if available,
444	utime(2). If called on a file descriptor, uses futimes(2) if available,	652	otherwise utime(2). If called on a file descriptor, uses futimens(2)
445	otherwise returns ENOSYS, so this is not portable.	653	or futimes(2) if available, otherwise returns ENOSYS, so this is not
		654	portable.
446		655
447	Examples:	656	Examples:
448		657
449	# set atime and mtime to current time (basically touch(1)):	658	# set atime and mtime to current time (basically touch(1)):
450	aio_utime "path", undef, undef;	659	aio_utime "path", undef, undef;
…		…
468	=item aio_truncate $fh_or_path, $offset, $callback->($status)	677	=item aio_truncate $fh_or_path, $offset, $callback->($status)
469		678
470	Works like truncate(2) or ftruncate(2).	679	Works like truncate(2) or ftruncate(2).
471		680
472		681
		682	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		683
		684	Allocates or frees disk space according to the C<$mode> argument. See the
		685	linux C<fallocate> documentation for details.
		686
		687	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		688	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		689	to deallocate a file range.
		690
		691	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		692	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		693	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		694	to unshare shared blocks (see your L<fallocate(2)> manpage).
		695
		696	The file system block size used by C<fallocate> is presumably the
		697	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		698	can dictate other limitations.
		699
		700	If C<fallocate> isn't available or cannot be emulated (currently no
		701	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		702
		703
473	=item aio_chmod $fh_or_path, $mode, $callback->($status)	704	=item aio_chmod $fh_or_path, $mode, $callback->($status)
474		705
475	Works like perl's C<chmod> function.	706	Works like perl's C<chmod> function.
476		707
477		708
…		…
479		710
480	Asynchronously unlink (delete) a file and call the callback with the	711	Asynchronously unlink (delete) a file and call the callback with the
481	result code.	712	result code.
482		713
483		714
484	=item aio_mknod $path, $mode, $dev, $callback->($status)	715	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
485		716
486	[EXPERIMENTAL]	717	[EXPERIMENTAL]
487		718
488	Asynchronously create a device node (or fifo). See mknod(2).	719	Asynchronously create a device node (or fifo). See mknod(2).
489		720
490	The only (POSIX-) portable way of calling this function is:	721	The only (POSIX-) portable way of calling this function is:
491		722
492	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	723	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
493		724
		725	See C<aio_stat> for info about some potentially helpful extra constants
		726	and functions.
494		727
495	=item aio_link $srcpath, $dstpath, $callback->($status)	728	=item aio_link $srcpath, $dstpath, $callback->($status)
496		729
497	Asynchronously create a new link to the existing object at C<$srcpath> at	730	Asynchronously create a new link to the existing object at C<$srcpath> at
498	the path C<$dstpath> and call the callback with the result code.	731	the path C<$dstpath> and call the callback with the result code.
…		…
502		735
503	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	736	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
504	the path C<$dstpath> and call the callback with the result code.	737	the path C<$dstpath> and call the callback with the result code.
505		738
506		739
507	=item aio_readlink $path, $callback->($link)	740	=item aio_readlink $pathname, $callback->($link)
508		741
509	Asynchronously read the symlink specified by C<$path> and pass it to	742	Asynchronously read the symlink specified by C<$path> and pass it to
510	the callback. If an error occurs, nothing or undef gets passed to the	743	the callback. If an error occurs, nothing or undef gets passed to the
511	callback.	744	callback.
512		745
513		746
		747	=item aio_realpath $pathname, $callback->($path)
		748
		749	Asynchronously make the path absolute and resolve any symlinks in
		750	C<$path>. The resulting path only consists of directories (same as
		751	L<Cwd::realpath>).
		752
		753	This request can be used to get the absolute path of the current working
		754	directory by passing it a path of F<.> (a single dot).
		755
		756
514	=item aio_rename $srcpath, $dstpath, $callback->($status)	757	=item aio_rename $srcpath, $dstpath, $callback->($status)
515		758
516	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	759	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
517	rename(2) and call the callback with the result code.	760	rename(2) and call the callback with the result code.
		761
		762	On systems that support the AIO::WD working directory abstraction
		763	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		764	of failing, C<rename> is called on the absolute path of C<$wd>.
		765
		766
		767	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		768
		769	Basically a version of C<aio_rename> with an additional C<$flags>
		770	argument. Calling this with C<$flags=0> is the same as calling
		771	C<aio_rename>.
		772
		773	Non-zero flags are currently only supported on GNU/Linux systems that
		774	support renameat2. Other systems fail with C<ENOSYS> in this case.
		775
		776	The following constants are available (missing ones are, as usual C<0>),
		777	see renameat2(2) for details:
		778
		779	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		780	and C<IO::AIO::RENAME_WHITEOUT>.
518		781
519		782
520	=item aio_mkdir $pathname, $mode, $callback->($status)	783	=item aio_mkdir $pathname, $mode, $callback->($status)
521		784
522	Asynchronously mkdir (create) a directory and call the callback with	785	Asynchronously mkdir (create) a directory and call the callback with
…		…
527	=item aio_rmdir $pathname, $callback->($status)	790	=item aio_rmdir $pathname, $callback->($status)
528		791
529	Asynchronously rmdir (delete) a directory and call the callback with the	792	Asynchronously rmdir (delete) a directory and call the callback with the
530	result code.	793	result code.
531		794
		795	On systems that support the AIO::WD working directory abstraction
		796	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		797	C<rmdir> is called on the absolute path of C<$wd>.
		798
532		799
533	=item aio_readdir $pathname, $callback->($entries)	800	=item aio_readdir $pathname, $callback->($entries)
534		801
535	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	802	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
536	directory (i.e. opendir + readdir + closedir). The entries will not be	803	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
540	array-ref with the filenames.	807	array-ref with the filenames.
541		808
542		809
543	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	810	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
544		811
545	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	812	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
546	behaviour and output format. In case of an error, C<$entries> will be	813	tune behaviour and output format. In case of an error, C<$entries> will be
547	C<undef>.	814	C<undef>.
548		815
549	The flags are a combination of the following constants, ORed together (the	816	The flags are a combination of the following constants, ORed together (the
550	flags will also be passed to the callback, possibly modified):	817	flags will also be passed to the callback, possibly modified):
551		818
552	=over 4	819	=over 4
553		820
554	=item IO::AIO::READDIR_DENTS	821	=item IO::AIO::READDIR_DENTS
555		822
556	When this flag is off, then the callback gets an arrayref with of names	823	Normally the callback gets an arrayref consisting of names only (as
557	only (as with C<aio_readdir>), otherwise it gets an arrayref with	824	with C<aio_readdir>). If this flag is set, then the callback gets an
558	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	825	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
559	entry in more detail.	826	single directory entry in more detail:
560		827
561	C<$name> is the name of the entry.	828	C<$name> is the name of the entry.
562		829
563	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	830	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
564		831
565	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	832	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
566	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	833	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
567	C<IO::AIO::DT_WHT>.	834	C<IO::AIO::DT_WHT>.
568		835
569	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	836	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
570	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	837	to know, you have to run stat yourself. Also, for speed/memory reasons,
571	scalars are read-only: you can not modify them.	838	the C<$type> scalars are read-only: you must not modify them.
572		839
573	C<$inode> is the inode number (which might not be exact on systems with 64	840	C<$inode> is the inode number (which might not be exact on systems with 64
574	bit inode numbers and 32 bit perls). This field has unspecified content on	841	bit inode numbers and 32 bit perls). This field has unspecified content on
575	systems that do not deliver the inode information.	842	systems that do not deliver the inode information.
576		843
577	=item IO::AIO::READDIR_DIRS_FIRST	844	=item IO::AIO::READDIR_DIRS_FIRST
578		845
579	When this flag is set, then the names will be returned in an order where	846	When this flag is set, then the names will be returned in an order where
580	likely directories come first. This is useful when you need to quickly	847	likely directories come first, in optimal stat order. This is useful when
581	find directories, or you want to find all directories while avoiding to	848	you need to quickly find directories, or you want to find all directories
582	stat() each entry.	849	while avoiding to stat() each entry.
583		850
584	If the system returns type information in readdir, then this is used	851	If the system returns type information in readdir, then this is used
585	to find directories directly. Otherwise, likely directories are files	852	to find directories directly. Otherwise, likely directories are names
586	beginning with ".", or otherwise files with no dots, of which files with	853	beginning with ".", or otherwise names with no dots, of which names with
587	short names are tried first.	854	short names are tried first.
588		855
589	=item IO::AIO::READDIR_STAT_ORDER	856	=item IO::AIO::READDIR_STAT_ORDER
590		857
591	When this flag is set, then the names will be returned in an order	858	When this flag is set, then the names will be returned in an order
592	suitable for stat()'ing each one. That is, when you plan to stat()	859	suitable for stat()'ing each one. That is, when you plan to stat() most or
593	all files in the given directory, then the returned order will likely	860	all files in the given directory, then the returned order will likely be
594	be fastest.	861	faster.
595		862
596	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then	863	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
597	the likely dirs come first, resulting in a less optimal stat order.	864	then the likely dirs come first, resulting in a less optimal stat order
		865	for stat'ing all entries, but likely a more optimal order for finding
		866	subdirectories.
598		867
599	=item IO::AIO::READDIR_FOUND_UNKNOWN	868	=item IO::AIO::READDIR_FOUND_UNKNOWN
600		869
601	This flag should not be set when calling C<aio_readdirx>. Instead, it	870	This flag should not be set when calling C<aio_readdirx>. Instead, it
602	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	871	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
603	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	872	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
604	C<$type>'s are known, which can be used to speed up some algorithms.	873	C<$type>'s are known, which can be used to speed up some algorithms.
605		874
606	=back	875	=back
607		876
608		877
		878	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		879
		880	Opens, reads and closes the given file. The data is put into C<$data>,
		881	which is resized as required.
		882
		883	If C<$offset> is negative, then it is counted from the end of the file.
		884
		885	If C<$length> is zero, then the remaining length of the file is
		886	used. Also, in this case, the same limitations to modifying C<$data> apply
		887	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		888	with C<substr>. If the size of the file is known, specifying a non-zero
		889	C<$length> results in a performance advantage.
		890
		891	This request is similar to the older C<aio_load> request, but since it is
		892	a single request, it might be more efficient to use.
		893
		894	Example: load F</etc/passwd> into C<$passwd>.
		895
		896	my $passwd;
		897	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		898	$_[0] >= 0
		899	or die "/etc/passwd: $!\n";
		900
		901	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		902	print $passwd;
		903	};
		904	IO::AIO::flush;
		905
		906
609	=item aio_load $path, $data, $callback->($status)	907	=item aio_load $pathname, $data, $callback->($status)
610		908
611	This is a composite request that tries to fully load the given file into	909	This is a composite request that tries to fully load the given file into
612	memory. Status is the same as with aio_read.	910	memory. Status is the same as with aio_read.
		911
		912	Using C<aio_slurp> might be more efficient, as it is a single request.
613		913
614	=cut	914	=cut
615		915
616	sub aio_load($$;$) {	916	sub aio_load($$;$) {
617	my ($path, undef, $cb) = @_;	917	my ($path, undef, $cb) = @_;
…		…
637	=item aio_copy $srcpath, $dstpath, $callback->($status)	937	=item aio_copy $srcpath, $dstpath, $callback->($status)
638		938
639	Try to copy the I<file> (directories not supported as either source or	939	Try to copy the I<file> (directories not supported as either source or
640	destination) from C<$srcpath> to C<$dstpath> and call the callback with	940	destination) from C<$srcpath> to C<$dstpath> and call the callback with
641	a status of C<0> (ok) or C<-1> (error, see C<$!>).	941	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		942
		943	Existing destination files will be truncated.
642		944
643	This is a composite request that creates the destination file with	945	This is a composite request that creates the destination file with
644	mode 0200 and copies the contents of the source file into it using	946	mode 0200 and copies the contents of the source file into it using
645	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	947	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
646	uid/gid, in that order.	948	uid/gid, in that order.
…		…
736	if ($_[0] && $! == EXDEV) {	1038	if ($_[0] && $! == EXDEV) {
737	aioreq_pri $pri;	1039	aioreq_pri $pri;
738	add $grp aio_copy $src, $dst, sub {	1040	add $grp aio_copy $src, $dst, sub {
739	$grp->result ($_[0]);	1041	$grp->result ($_[0]);
740		1042
741	if (!$_[0]) {	1043	unless ($_[0]) {
742	aioreq_pri $pri;	1044	aioreq_pri $pri;
743	add $grp aio_unlink $src;	1045	add $grp aio_unlink $src;
744	}	1046	}
745	};	1047	};
746	} else {	1048	} else {
…		…
749	};	1051	};
750		1052
751	$grp	1053	$grp
752	}	1054	}
753		1055
754	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1056	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
755		1057
756	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1058	Scans a directory (similar to C<aio_readdir>) but additionally tries to
757	efficiently separate the entries of directory C<$path> into two sets of	1059	efficiently separate the entries of directory C<$path> into two sets of
758	names, directories you can recurse into (directories), and ones you cannot	1060	names, directories you can recurse into (directories), and ones you cannot
759	recurse into (everything else, including symlinks to directories).	1061	recurse into (everything else, including symlinks to directories).
760		1062
761	C<aio_scandir> is a composite request that creates of many sub requests_	1063	C<aio_scandir> is a composite request that generates many sub requests.
762	C<$maxreq> specifies the maximum number of outstanding aio requests that	1064	C<$maxreq> specifies the maximum number of outstanding aio requests that
763	this function generates. If it is C<< <= 0 >>, then a suitable default	1065	this function generates. If it is C<< <= 0 >>, then a suitable default
764	will be chosen (currently 4).	1066	will be chosen (currently 4).
765		1067
766	On error, the callback is called without arguments, otherwise it receives	1068	On error, the callback is called without arguments, otherwise it receives
…		…
790	Then entries will be sorted into likely directories a non-initial dot	1092	Then entries will be sorted into likely directories a non-initial dot
791	currently) and likely non-directories (see C<aio_readdirx>). Then every	1093	currently) and likely non-directories (see C<aio_readdirx>). Then every
792	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1094	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
793	in order of their inode numbers. If that succeeds, it assumes that the	1095	in order of their inode numbers. If that succeeds, it assumes that the
794	entry is a directory or a symlink to directory (which will be checked	1096	entry is a directory or a symlink to directory (which will be checked
795	seperately). This is often faster than stat'ing the entry itself because	1097	separately). This is often faster than stat'ing the entry itself because
796	filesystems might detect the type of the entry without reading the inode	1098	filesystems might detect the type of the entry without reading the inode
797	data (e.g. ext2fs filetype feature), even on systems that cannot return	1099	data (e.g. ext2fs filetype feature), even on systems that cannot return
798	the filetype information on readdir.	1100	the filetype information on readdir.
799		1101
800	If the known number of directories (link count - 2) has been reached, the	1102	If the known number of directories (link count - 2) has been reached, the
…		…
816		1118
817	my $grp = aio_group $cb;	1119	my $grp = aio_group $cb;
818		1120
819	$maxreq = 4 if $maxreq <= 0;	1121	$maxreq = 4 if $maxreq <= 0;
820		1122
821	# stat once	1123	# get a wd object
822	aioreq_pri $pri;	1124	aioreq_pri $pri;
823	add $grp aio_stat $path, sub {	1125	add $grp aio_wd $path, sub {
		1126	$_[0]
824	return $grp->result () if $_[0];	1127	or return $grp->result ();
825	my $now = time;
826	my $hash1 = join ":", (stat _)[0,1,3,7,9];
827		1128
828	# read the directory entries	1129	my $wd = [shift, "."];
		1130
		1131	# stat once
829	aioreq_pri $pri;	1132	aioreq_pri $pri;
830	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1133	add $grp aio_stat $wd, sub {
831	my $entries = shift
832	or return $grp->result ();	1134	return $grp->result () if $_[0];
		1135	my $now = time;
		1136	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		1137	my $rdxflags = READDIR_DIRS_FIRST;
833		1138
834	# stat the dir another time	1139	if ((stat _)[3] < 2) {
		1140	# at least one non-POSIX filesystem exists
		1141	# that returns useful DT_type values: btrfs,
		1142	# so optimise for this here by requesting dents
		1143	$rdxflags |= READDIR_DENTS;
		1144	}
		1145
		1146	# read the directory entries
835	aioreq_pri $pri;	1147	aioreq_pri $pri;
836	add $grp aio_stat $path, sub {	1148	add $grp aio_readdirx $wd, $rdxflags, sub {
837	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1149	my ($entries, $flags) = @_
		1150	or return $grp->result ();
838		1151
		1152	if ($rdxflags & READDIR_DENTS) {
		1153	# if we requested type values, see if we can use them directly.
		1154
		1155	# if there were any DT_UNKNOWN entries then we assume we
		1156	# don't know. alternatively, we could assume that if we get
		1157	# one DT_DIR, then all directories are indeed marked with
		1158	# DT_DIR, but this seems not required for btrfs, and this
		1159	# is basically the "btrfs can't get it's act together" code
		1160	# branch.
		1161	unless ($flags & READDIR_FOUND_UNKNOWN) {
		1162	# now we have valid DT_ information for all entries,
		1163	# so use it as an optimisation without further stat's.
		1164	# they must also all be at the beginning of @$entries
		1165	# by now.
		1166
839	my $ndirs;	1167	my $dirs;
840		1168
841	# take the slow route if anything looks fishy
842	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
843	$ndirs = -1;
844	} else {
845	# if nlink == 2, we are finished
846	# for non-posix-fs's, we rely on nlink < 2
847	$ndirs = (stat _)[3] - 2
848	or return $grp->result ([], $entries);
849	}
850
851	my (@dirs, @nondirs);
852
853	my $statgrp = add $grp aio_group sub {
854	$grp->result (\@dirs, \@nondirs);
855	};
856
857	limit $statgrp $maxreq;
858	feed $statgrp sub {
859	return unless @$entries;
860	my $entry = shift @$entries;
861
862	aioreq_pri $pri;
863	add $statgrp aio_stat "$path/$entry/.", sub {
864	if ($_[0] < 0) {	1169	if (@$entries) {
865	push @nondirs, $entry;	1170	for (0 .. $#$entries) {
866	} else {	1171	if ($entries->[$_][1] != DT_DIR) {
867	# need to check for real directory	1172	# splice out directories
868	aioreq_pri $pri;	1173	$dirs = [splice @$entries, 0, $_];
869	add $statgrp aio_lstat "$path/$entry", sub {
870	if (-d _) {
871	push @dirs, $entry;
872
873	unless (--$ndirs) {
874	push @nondirs, @$entries;
875	feed $statgrp;
876	}	1174	last;
877	} else {
878	push @nondirs, $entry;
879	}	1175	}
880	}	1176	}
		1177
		1178	# if we didn't find any non-dir, then all entries are dirs
		1179	unless ($dirs) {
		1180	($dirs, $entries) = ($entries, []);
		1181	}
		1182	} else {
		1183	# directory is empty, so there are no sbdirs
		1184	$dirs = [];
881	}	1185	}
		1186
		1187	# either splice'd the directories out or the dir was empty.
		1188	# convert dents to filenames
		1189	$_ = $_->[0] for @$dirs;
		1190	$_ = $_->[0] for @$entries;
		1191
		1192	return $grp->result ($dirs, $entries);
		1193	}
		1194
		1195	# cannot use, so return to our old ways
		1196	# by pretending we only scanned for names.
		1197	$_ = $_->[0] for @$entries;
		1198	}
		1199
		1200	# stat the dir another time
		1201	aioreq_pri $pri;
		1202	add $grp aio_stat $wd, sub {
		1203	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		1204
		1205	my $ndirs;
		1206
		1207	# take the slow route if anything looks fishy
		1208	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
		1209	$ndirs = -1;
		1210	} else {
		1211	# if nlink == 2, we are finished
		1212	# for non-posix-fs's, we rely on nlink < 2
		1213	$ndirs = (stat _)[3] - 2
		1214	or return $grp->result ([], $entries);
		1215	}
		1216
		1217	my (@dirs, @nondirs);
		1218
		1219	my $statgrp = add $grp aio_group sub {
		1220	$grp->result (\@dirs, \@nondirs);
		1221	};
		1222
		1223	limit $statgrp $maxreq;
		1224	feed $statgrp sub {
		1225	return unless @$entries;
		1226	my $entry = shift @$entries;
		1227
		1228	aioreq_pri $pri;
		1229	$wd->[1] = "$entry/.";
		1230	add $statgrp aio_stat $wd, sub {
		1231	if ($_[0] < 0) {
		1232	push @nondirs, $entry;
		1233	} else {
		1234	# need to check for real directory
		1235	aioreq_pri $pri;
		1236	$wd->[1] = $entry;
		1237	add $statgrp aio_lstat $wd, sub {
		1238	if (-d _) {
		1239	push @dirs, $entry;
		1240
		1241	unless (--$ndirs) {
		1242	push @nondirs, @$entries;
		1243	feed $statgrp;
		1244	}
		1245	} else {
		1246	push @nondirs, $entry;
		1247	}
		1248	}
		1249	}
		1250	};
882	};	1251	};
883	};	1252	};
884	};	1253	};
885	};	1254	};
886	};	1255	};
887		1256
888	$grp	1257	$grp
889	}	1258	}
890		1259
891	=item aio_rmtree $path, $callback->($status)	1260	=item aio_rmtree $pathname, $callback->($status)
892		1261
893	Delete a directory tree starting (and including) C<$path>, return the	1262	Delete a directory tree starting (and including) C<$path>, return the
894	status of the final C<rmdir> only. This is a composite request that	1263	status of the final C<rmdir> only. This is a composite request that
895	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1264	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
896	everything else.	1265	everything else.
897		1266
898	=cut	1267	=cut
899		1268
…		…
921	};	1290	};
922		1291
923	$grp	1292	$grp
924	}	1293	}
925		1294
		1295	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1296
		1297	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1298
		1299	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1300	they execute asynchronously and pass the return value to the callback.
		1301
		1302	Both calls can be used for a lot of things, some of which make more sense
		1303	to run asynchronously in their own thread, while some others make less
		1304	sense. For example, calls that block waiting for external events, such
		1305	as locking, will also lock down an I/O thread while it is waiting, which
		1306	can deadlock the whole I/O system. At the same time, there might be no
		1307	alternative to using a thread to wait.
		1308
		1309	So in general, you should only use these calls for things that do
		1310	(filesystem) I/O, not for things that wait for other events (network,
		1311	other processes), although if you are careful and know what you are doing,
		1312	you still can.
		1313
		1314	The following constants are available and can be used for normal C<ioctl>
		1315	and C<fcntl> as well (missing ones are, as usual C<0>):
		1316
		1317	C<F_DUPFD_CLOEXEC>,
		1318
		1319	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1320
		1321	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1322
		1323	C<F_ADD_SEALS>, C<F_GET_SEALS>, C<F_SEAL_SEAL>, C<F_SEAL_SHRINK>, C<F_SEAL_GROW> and
		1324	C<F_SEAL_WRITE>.
		1325
		1326	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1327	C<FS_IOC_FIEMAP>.
		1328
		1329	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1330	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1331
		1332	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1333	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1334	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1335	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1336	C<FS_FL_USER_MODIFIABLE>.
		1337
		1338	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1339	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1340	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1341	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1342
926	=item aio_sync $callback->($status)	1343	=item aio_sync $callback->($status)
927		1344
928	Asynchronously call sync and call the callback when finished.	1345	Asynchronously call sync and call the callback when finished.
929		1346
930	=item aio_fsync $fh, $callback->($status)	1347	=item aio_fsync $fh, $callback->($status)
…		…
937	Asynchronously call fdatasync on the given filehandle and call the	1354	Asynchronously call fdatasync on the given filehandle and call the
938	callback with the fdatasync result code.	1355	callback with the fdatasync result code.
939		1356
940	If this call isn't available because your OS lacks it or it couldn't be	1357	If this call isn't available because your OS lacks it or it couldn't be
941	detected, it will be emulated by calling C<fsync> instead.	1358	detected, it will be emulated by calling C<fsync> instead.
		1359
		1360	=item aio_syncfs $fh, $callback->($status)
		1361
		1362	Asynchronously call the syncfs syscall to sync the filesystem associated
		1363	to the given filehandle and call the callback with the syncfs result
		1364	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1365	errno to C<ENOSYS> nevertheless.
942		1366
943	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1367	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
944		1368
945	Sync the data portion of the file specified by C<$offset> and C<$length>	1369	Sync the data portion of the file specified by C<$offset> and C<$length>
946	to disk (but NOT the metadata), by calling the Linux-specific	1370	to disk (but NOT the metadata), by calling the Linux-specific
…		…
950	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1374	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
951	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1375	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
952	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1376	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
953	manpage for details.	1377	manpage for details.
954		1378
955	=item aio_pathsync $path, $callback->($status)	1379	=item aio_pathsync $pathname, $callback->($status)
956		1380
957	This request tries to open, fsync and close the given path. This is a	1381	This request tries to open, fsync and close the given path. This is a
958	composite request intended to sync directories after directory operations	1382	composite request intended to sync directories after directory operations
959	(E.g. rename). This might not work on all operating systems or have any	1383	(E.g. rename). This might not work on all operating systems or have any
960	specific effect, but usually it makes sure that directory changes get	1384	specific effect, but usually it makes sure that directory changes get
…		…
991	};	1415	};
992		1416
993	$grp	1417	$grp
994	}	1418	}
995		1419
996	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1420	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
997		1421
998	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1422	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
999	scalars (see the L<Sys::Mmap> or L<Mmap> modules for details on this, note	1423	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1424	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1000	that the scalar must only be modified in-place while an aio operation is	1425	scalar must only be modified in-place while an aio operation is pending on
1001	pending on it).	1426	it).
1002		1427
1003	It calls the C<msync> function of your OS, if available, with the memory	1428	It calls the C<msync> function of your OS, if available, with the memory
1004	area starting at C<$offset> in the string and ending C<$length> bytes	1429	area starting at C<$offset> in the string and ending C<$length> bytes
1005	later. If C<$length> is negative, counts from the end, and if C<$length>	1430	later. If C<$length> is negative, counts from the end, and if C<$length>
1006	is C<undef>, then it goes till the end of the string. The flags can be	1431	is C<undef>, then it goes till the end of the string. The flags can be
1007	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1432	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1008	C<IO::AIO::MS_SYNC>.	1433	C<IO::AIO::MS_INVALIDATE>.
1009		1434
1010	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1435	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1011		1436
1012	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1437	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1013	scalars.	1438	scalars.
1014		1439
1015	It touches (reads or writes) all memory pages in the specified	1440	It touches (reads or writes) all memory pages in the specified
1016	range inside the scalar. All caveats and parameters are the same	1441	range inside the scalar. All caveats and parameters are the same
1017	as for C<aio_msync>, above, except for flags, which must be either	1442	as for C<aio_msync>, above, except for flags, which must be either
1018	C<0> (which reads all pages and ensures they are instantiated) or	1443	C<0> (which reads all pages and ensures they are instantiated) or
1019	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1444	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1020	writing an octet from it, which dirties the page).	1445	writing an octet from it, which dirties the page).
		1446
		1447	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1448
		1449	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1450	scalars.
		1451
		1452	It reads in all the pages of the underlying storage into memory (if any)
		1453	and locks them, so they are not getting swapped/paged out or removed.
		1454
		1455	If C<$length> is undefined, then the scalar will be locked till the end.
		1456
		1457	On systems that do not implement C<mlock>, this function returns C<-1>
		1458	and sets errno to C<ENOSYS>.
		1459
		1460	Note that the corresponding C<munlock> is synchronous and is
		1461	documented under L<MISCELLANEOUS FUNCTIONS>.
		1462
		1463	Example: open a file, mmap and mlock it - both will be undone when
		1464	C<$data> gets destroyed.
		1465
		1466	open my $fh, "<", $path or die "$path: $!";
		1467	my $data;
		1468	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1469	aio_mlock $data; # mlock in background
		1470
		1471	=item aio_mlockall $flags, $callback->($status)
		1472
		1473	Calls the C<mlockall> function with the given C<$flags> (a
		1474	combination of C<IO::AIO::MCL_CURRENT>, C<IO::AIO::MCL_FUTURE> and
		1475	C<IO::AIO::MCL_ONFAULT>).
		1476
		1477	On systems that do not implement C<mlockall>, this function returns C<-1>
		1478	and sets errno to C<ENOSYS>. Similarly, flag combinations not supported
		1479	by the system result in a return value of C<-1> with errno being set to
		1480	C<EINVAL>.
		1481
		1482	Note that the corresponding C<munlockall> is synchronous and is
		1483	documented under L<MISCELLANEOUS FUNCTIONS>.
		1484
		1485	Example: asynchronously lock all current and future pages into memory.
		1486
		1487	aio_mlockall IO::AIO::MCL_FUTURE;
		1488
		1489	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1490
		1491	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1492	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1493	the ioctl is not available on your OS, then this request will fail with
		1494	C<ENOSYS>.
		1495
		1496	C<$start> is the starting offset to query extents for, C<$length> is the
		1497	size of the range to query - if it is C<undef>, then the whole file will
		1498	be queried.
		1499
		1500	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1501	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1502	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1503	the data portion.
		1504
		1505	C<$count> is the maximum number of extent records to return. If it is
		1506	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1507	case, if it is C<0>, then the callback receives the number of extents
		1508	instead of the extents themselves (which is unreliable, see below).
		1509
		1510	If an error occurs, the callback receives no arguments. The special
		1511	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1512
		1513	Otherwise, the callback receives an array reference with extent
		1514	structures. Each extent structure is an array reference itself, with the
		1515	following members:
		1516
		1517	[$logical, $physical, $length, $flags]
		1518
		1519	Flags is any combination of the following flag values (typically either C<0>
		1520	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1521
		1522	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1523	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1524	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1525	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1526	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1527	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1528
		1529	At the time of this writing (Linux 3.2), this request is unreliable unless
		1530	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1531	it to return all extents of a range for files with a large number of
		1532	extents. The code (only) works around all these issues if C<$count> is
		1533	C<undef>.
1021		1534
1022	=item aio_group $callback->(...)	1535	=item aio_group $callback->(...)
1023		1536
1024	This is a very special aio request: Instead of doing something, it is a	1537	This is a very special aio request: Instead of doing something, it is a
1025	container for other aio requests, which is useful if you want to bundle	1538	container for other aio requests, which is useful if you want to bundle
…		…
1062	like sleep and file handle readable/writable, the overhead this creates is	1575	like sleep and file handle readable/writable, the overhead this creates is
1063	immense (it blocks a thread for a long time) so do not use this function	1576	immense (it blocks a thread for a long time) so do not use this function
1064	except to put your application under artificial I/O pressure.	1577	except to put your application under artificial I/O pressure.
1065		1578
1066	=back	1579	=back
		1580
		1581
		1582	=head2 IO::AIO::WD - multiple working directories
		1583
		1584	Your process only has one current working directory, which is used by all
		1585	threads. This makes it hard to use relative paths (some other component
		1586	could call C<chdir> at any time, and it is hard to control when the path
		1587	will be used by IO::AIO).
		1588
		1589	One solution for this is to always use absolute paths. This usually works,
		1590	but can be quite slow (the kernel has to walk the whole path on every
		1591	access), and can also be a hassle to implement.
		1592
		1593	Newer POSIX systems have a number of functions (openat, fdopendir,
		1594	futimensat and so on) that make it possible to specify working directories
		1595	per operation.
		1596
		1597	For portability, and because the clowns who "designed", or shall I write,
		1598	perpetrated this new interface were obviously half-drunk, this abstraction
		1599	cannot be perfect, though.
		1600
		1601	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1602	object. This object stores the canonicalised, absolute version of the
		1603	path, and on systems that allow it, also a directory file descriptor.
		1604
		1605	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1606	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1607	object and a pathname instead (or the IO::AIO::WD object alone, which
		1608	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1609	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1610	to that IO::AIO::WD object.
		1611
		1612	For example, to get a wd object for F</etc> and then stat F<passwd>
		1613	inside, you would write:
		1614
		1615	aio_wd "/etc", sub {
		1616	my $etcdir = shift;
		1617
		1618	# although $etcdir can be undef on error, there is generally no reason
		1619	# to check for errors here, as aio_stat will fail with ENOENT
		1620	# when $etcdir is undef.
		1621
		1622	aio_stat [$etcdir, "passwd"], sub {
		1623	# yay
		1624	};
		1625	};
		1626
		1627	The fact that C<aio_wd> is a request and not a normal function shows that
		1628	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1629	which is why it is done asynchronously.
		1630
		1631	To stat the directory obtained with C<aio_wd> above, one could write
		1632	either of the following three request calls:
		1633
		1634	aio_lstat "/etc" , sub { ... # pathname as normal string
		1635	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1636	aio_lstat $wd , sub { ... # shorthand for the previous
		1637
		1638	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1639	object and the pathname string, so you could write the following without
		1640	causing any issues due to C<$path> getting reused:
		1641
		1642	my $path = [$wd, undef];
		1643
		1644	for my $name (qw(abc def ghi)) {
		1645	$path->[1] = $name;
		1646	aio_stat $path, sub {
		1647	# ...
		1648	};
		1649	}
		1650
		1651	There are some caveats: when directories get renamed (or deleted), the
		1652	pathname string doesn't change, so will point to the new directory (or
		1653	nowhere at all), while the directory fd, if available on the system,
		1654	will still point to the original directory. Most functions accepting a
		1655	pathname will use the directory fd on newer systems, and the string on
		1656	older systems. Some functions (such as C<aio_realpath>) will always rely on
		1657	the string form of the pathname.
		1658
		1659	So this functionality is mainly useful to get some protection against
		1660	C<chdir>, to easily get an absolute path out of a relative path for future
		1661	reference, and to speed up doing many operations in the same directory
		1662	(e.g. when stat'ing all files in a directory).
		1663
		1664	The following functions implement this working directory abstraction:
		1665
		1666	=over 4
		1667
		1668	=item aio_wd $pathname, $callback->($wd)
		1669
		1670	Asynchonously canonicalise the given pathname and convert it to an
		1671	IO::AIO::WD object representing it. If possible and supported on the
		1672	system, also open a directory fd to speed up pathname resolution relative
		1673	to this working directory.
		1674
		1675	If something goes wrong, then C<undef> is passwd to the callback instead
		1676	of a working directory object and C<$!> is set appropriately. Since
		1677	passing C<undef> as working directory component of a pathname fails the
		1678	request with C<ENOENT>, there is often no need for error checking in the
		1679	C<aio_wd> callback, as future requests using the value will fail in the
		1680	expected way.
		1681
		1682	=item IO::AIO::CWD
		1683
		1684	This is a compile time constant (object) that represents the process
		1685	current working directory.
		1686
		1687	Specifying this object as working directory object for a pathname is as if
		1688	the pathname would be specified directly, without a directory object. For
		1689	example, these calls are functionally identical:
		1690
		1691	aio_stat "somefile", sub { ... };
		1692	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1693
		1694	=back
		1695
		1696	To recover the path associated with an IO::AIO::WD object, you can use
		1697	C<aio_realpath>:
		1698
		1699	aio_realpath $wd, sub {
		1700	warn "path is $_[0]\n";
		1701	};
		1702
		1703	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1704	sometimes, fall back to using an absolue path.
1067		1705
1068	=head2 IO::AIO::REQ CLASS	1706	=head2 IO::AIO::REQ CLASS
1069		1707
1070	All non-aggregate C<aio_*> functions return an object of this class when	1708	All non-aggregate C<aio_*> functions return an object of this class when
1071	called in non-void context.	1709	called in non-void context.
…		…
1189		1827
1190	Sets a feeder/generator on this group: every group can have an attached	1828	Sets a feeder/generator on this group: every group can have an attached
1191	generator that generates requests if idle. The idea behind this is that,	1829	generator that generates requests if idle. The idea behind this is that,
1192	although you could just queue as many requests as you want in a group,	1830	although you could just queue as many requests as you want in a group,
1193	this might starve other requests for a potentially long time. For example,	1831	this might starve other requests for a potentially long time. For example,
1194	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1832	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1195	delaying any later requests for a long time.	1833	requests, delaying any later requests for a long time.
1196		1834
1197	To avoid this, and allow incremental generation of requests, you can	1835	To avoid this, and allow incremental generation of requests, you can
1198	instead a group and set a feeder on it that generates those requests. The	1836	instead a group and set a feeder on it that generates those requests. The
1199	feed callback will be called whenever there are few enough (see C<limit>,	1837	feed callback will be called whenever there are few enough (see C<limit>,
1200	below) requests active in the group itself and is expected to queue more	1838	below) requests active in the group itself and is expected to queue more
…		…
1232	The default value for the limit is C<0>, but note that setting a feeder	1870	The default value for the limit is C<0>, but note that setting a feeder
1233	automatically bumps it up to C<2>.	1871	automatically bumps it up to C<2>.
1234		1872
1235	=back	1873	=back
1236		1874
		1875
1237	=head2 SUPPORT FUNCTIONS	1876	=head2 SUPPORT FUNCTIONS
1238		1877
1239	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1878	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1240		1879
1241	=over 4	1880	=over 4
…		…
1249		1888
1250	See C<poll_cb> for an example.	1889	See C<poll_cb> for an example.
1251		1890
1252	=item IO::AIO::poll_cb	1891	=item IO::AIO::poll_cb
1253		1892
1254	Process some outstanding events on the result pipe. You have to call this	1893	Process some requests that have reached the result phase (i.e. they have
1255	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1894	been executed but the results are not yet reported). You have to call
1256	returned earlier for whatever reason. Returns immediately when no events	1895	this "regularly" to finish outstanding requests.
1257	are outstanding. The amount of events processed depends on the settings of
1258	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1259		1896
		1897	Returns C<0> if all events could be processed (or there were no
		1898	events to process), or C<-1> if it returned earlier for whatever
		1899	reason. Returns immediately when no events are outstanding. The amount
		1900	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
		1901	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
		1902
1260	If not all requests were processed for whatever reason, the filehandle	1903	If not all requests were processed for whatever reason, the poll file
1261	will still be ready when C<poll_cb> returns, so normally you don't have to	1904	descriptor will still be ready when C<poll_cb> returns, so normally you
1262	do anything special to have it called later.	1905	don't have to do anything special to have it called later.
		1906
		1907	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1908	ready, it can be beneficial to call this function from loops which submit
		1909	a lot of requests, to make sure the results get processed when they become
		1910	available and not just when the loop is finished and the event loop takes
		1911	over again. This function returns very fast when there are no outstanding
		1912	requests.
1263		1913
1264	Example: Install an Event watcher that automatically calls	1914	Example: Install an Event watcher that automatically calls
1265	IO::AIO::poll_cb with high priority (more examples can be found in the	1915	IO::AIO::poll_cb with high priority (more examples can be found in the
1266	SYNOPSIS section, at the top of this document):	1916	SYNOPSIS section, at the top of this document):
1267		1917
1268	Event->io (fd => IO::AIO::poll_fileno,	1918	Event->io (fd => IO::AIO::poll_fileno,
1269	poll => 'r', async => 1,	1919	poll => 'r', async => 1,
1270	cb => \&IO::AIO::poll_cb);	1920	cb => \&IO::AIO::poll_cb);
		1921
		1922	=item IO::AIO::poll_wait
		1923
		1924	Wait until either at least one request is in the result phase or no
		1925	requests are outstanding anymore.
		1926
		1927	This is useful if you want to synchronously wait for some requests to
		1928	become ready, without actually handling them.
		1929
		1930	See C<nreqs> for an example.
		1931
		1932	=item IO::AIO::poll
		1933
		1934	Waits until some requests have been handled.
		1935
		1936	Returns the number of requests processed, but is otherwise strictly
		1937	equivalent to:
		1938
		1939	IO::AIO::poll_wait, IO::AIO::poll_cb
		1940
		1941	=item IO::AIO::flush
		1942
		1943	Wait till all outstanding AIO requests have been handled.
		1944
		1945	Strictly equivalent to:
		1946
		1947	IO::AIO::poll_wait, IO::AIO::poll_cb
		1948	while IO::AIO::nreqs;
		1949
		1950	This function can be useful at program aborts, to make sure outstanding
		1951	I/O has been done (C<IO::AIO> uses an C<END> block which already calls
		1952	this function on normal exits), or when you are merely using C<IO::AIO>
		1953	for its more advanced functions, rather than for async I/O, e.g.:
		1954
		1955	my ($dirs, $nondirs);
		1956	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1957	IO::AIO::flush;
		1958	# $dirs, $nondirs are now set
1271		1959
1272	=item IO::AIO::max_poll_reqs $nreqs	1960	=item IO::AIO::max_poll_reqs $nreqs
1273		1961
1274	=item IO::AIO::max_poll_time $seconds	1962	=item IO::AIO::max_poll_time $seconds
1275		1963
…		…
1300	# use a low priority so other tasks have priority	1988	# use a low priority so other tasks have priority
1301	Event->io (fd => IO::AIO::poll_fileno,	1989	Event->io (fd => IO::AIO::poll_fileno,
1302	poll => 'r', nice => 1,	1990	poll => 'r', nice => 1,
1303	cb => &IO::AIO::poll_cb);	1991	cb => &IO::AIO::poll_cb);
1304		1992
1305	=item IO::AIO::poll_wait
1306
1307	If there are any outstanding requests and none of them in the result
1308	phase, wait till the result filehandle becomes ready for reading (simply
1309	does a C<select> on the filehandle. This is useful if you want to
1310	synchronously wait for some requests to finish).
1311
1312	See C<nreqs> for an example.
1313
1314	=item IO::AIO::poll
1315
1316	Waits until some requests have been handled.
1317
1318	Returns the number of requests processed, but is otherwise strictly
1319	equivalent to:
1320
1321	IO::AIO::poll_wait, IO::AIO::poll_cb
1322
1323	=item IO::AIO::flush
1324
1325	Wait till all outstanding AIO requests have been handled.
1326
1327	Strictly equivalent to:
1328
1329	IO::AIO::poll_wait, IO::AIO::poll_cb
1330	while IO::AIO::nreqs;
1331
1332	=back	1993	=back
		1994
1333		1995
1334	=head3 CONTROLLING THE NUMBER OF THREADS	1996	=head3 CONTROLLING THE NUMBER OF THREADS
1335		1997
1336	=over	1998	=over
1337		1999
…		…
1369		2031
1370	Under normal circumstances you don't need to call this function.	2032	Under normal circumstances you don't need to call this function.
1371		2033
1372	=item IO::AIO::max_idle $nthreads	2034	=item IO::AIO::max_idle $nthreads
1373		2035
1374	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	2036	Limit the number of threads (default: 4) that are allowed to idle
1375	threads that did not get a request to process within 10 seconds). That	2037	(i.e., threads that did not get a request to process within the idle
1376	means if a thread becomes idle while C<$nthreads> other threads are also	2038	timeout (default: 10 seconds). That means if a thread becomes idle while
1377	idle, it will free its resources and exit.	2039	C<$nthreads> other threads are also idle, it will free its resources and
		2040	exit.
1378		2041
1379	This is useful when you allow a large number of threads (e.g. 100 or 1000)	2042	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1380	to allow for extremely high load situations, but want to free resources	2043	to allow for extremely high load situations, but want to free resources
1381	under normal circumstances (1000 threads can easily consume 30MB of RAM).	2044	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1382		2045
1383	The default is probably ok in most situations, especially if thread	2046	The default is probably ok in most situations, especially if thread
1384	creation is fast. If thread creation is very slow on your system you might	2047	creation is fast. If thread creation is very slow on your system you might
1385	want to use larger values.	2048	want to use larger values.
1386		2049
		2050	=item IO::AIO::idle_timeout $seconds
		2051
		2052	Sets the minimum idle timeout (default 10) after which worker threads are
		2053	allowed to exit. SEe C<IO::AIO::max_idle>.
		2054
1387	=item IO::AIO::max_outstanding $maxreqs	2055	=item IO::AIO::max_outstanding $maxreqs
		2056
		2057	Sets the maximum number of outstanding requests to C<$nreqs>. If
		2058	you do queue up more than this number of requests, the next call to
		2059	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		2060	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		2061	longer exceeded.
		2062
		2063	In other words, this setting does not enforce a queue limit, but can be
		2064	used to make poll functions block if the limit is exceeded.
1388		2065
1389	This is a very bad function to use in interactive programs because it	2066	This is a very bad function to use in interactive programs because it
1390	blocks, and a bad way to reduce concurrency because it is inexact: Better	2067	blocks, and a bad way to reduce concurrency because it is inexact: Better
1391	use an C<aio_group> together with a feed callback.	2068	use an C<aio_group> together with a feed callback.
1392		2069
1393	Sets the maximum number of outstanding requests to C<$nreqs>. If you	2070	Its main use is in scripts without an event loop - when you want to stat
1394	do queue up more than this number of requests, the next call to the	2071	a lot of files, you can write something like this:
1395	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1396	function will block until the limit is no longer exceeded.
1397		2072
1398	The default value is very large, so there is no practical limit on the	2073	IO::AIO::max_outstanding 32;
1399	number of outstanding requests.
1400		2074
1401	You can still queue as many requests as you want. Therefore,	2075	for my $path (...) {
1402	C<max_outstanding> is mainly useful in simple scripts (with low values) or	2076	aio_stat $path , ...;
1403	as a stop gap to shield against fatal memory overflow (with large values).	2077	IO::AIO::poll_cb;
		2078	}
		2079
		2080	IO::AIO::flush;
		2081
		2082	The call to C<poll_cb> inside the loop will normally return instantly, but
		2083	as soon as more thna C<32> reqeusts are in-flight, it will block until
		2084	some requests have been handled. This keeps the loop from pushing a large
		2085	number of C<aio_stat> requests onto the queue.
		2086
		2087	The default value for C<max_outstanding> is very large, so there is no
		2088	practical limit on the number of outstanding requests.
1404		2089
1405	=back	2090	=back
		2091
1406		2092
1407	=head3 STATISTICAL INFORMATION	2093	=head3 STATISTICAL INFORMATION
1408		2094
1409	=over	2095	=over
1410		2096
…		…
1428	Returns the number of requests currently in the pending state (executed,	2114	Returns the number of requests currently in the pending state (executed,
1429	but not yet processed by poll_cb).	2115	but not yet processed by poll_cb).
1430		2116
1431	=back	2117	=back
1432		2118
		2119
		2120	=head3 SUBSECOND STAT TIME ACCESS
		2121
		2122	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2123	generally find access/modification and change times with subsecond time
		2124	accuracy of the system supports it, but perl's built-in functions only
		2125	return the integer part.
		2126
		2127	The following functions return the timestamps of the most recent
		2128	stat with subsecond precision on most systems and work both after
		2129	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2130	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2131	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2132
		2133	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2134	full resolution without rounding and work with standard perl C<stat>,
		2135	alleviating the need to call the special C<Time::HiRes> functions, which
		2136	do not act like their perl counterparts.
		2137
		2138	On operating systems or file systems where subsecond time resolution is
		2139	not supported or could not be detected, a fractional part of C<0> is
		2140	returned, so it is always safe to call these functions.
		2141
		2142	=over 4
		2143
		2144	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		2145
		2146	Return the access, modication, change or birth time, respectively,
		2147	including fractional part. Due to the limited precision of floating point,
		2148	the accuracy on most platforms is only a bit better than milliseconds
		2149	for times around now - see the I<nsec> function family, below, for full
		2150	accuracy.
		2151
		2152	File birth time is only available when the OS and perl support it (on
		2153	FreeBSD and NetBSD at the time of this writing, although support is
		2154	adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
		2155	it). On systems where it isn't available, C<0> is currently returned, but
		2156	this might change to C<undef> in a future version.
		2157
		2158	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		2159
		2160	Returns access, modification, change and birth time all in one go, and
		2161	maybe more times in the future version.
		2162
		2163	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		2164
		2165	Return the fractional access, modifcation, change or birth time, in nanoseconds,
		2166	as an integer in the range C<0> to C<999999999>.
		2167
		2168	Note that no accessors are provided for access, modification and
		2169	change times - you need to get those from C<stat _> if required (C<int
		2170	IO::AIO::st_atime> and so on will I<not> generally give you the correct
		2171	value).
		2172
		2173	=item $seconds = IO::AIO::st_btimesec
		2174
		2175	The (integral) seconds part of the file birth time, if available.
		2176
		2177	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		2178
		2179	Like the functions above, but returns all four times in one go (and maybe
		2180	more in future versions).
		2181
		2182	=item $counter = IO::AIO::st_gen
		2183
		2184	Returns the generation counter (in practice this is just a random number)
		2185	of the file. This is only available on platforms which have this member in
		2186	their C<struct stat> (most BSDs at the time of this writing) and generally
		2187	only to the root usert. If unsupported, C<0> is returned, but this might
		2188	change to C<undef> in a future version.
		2189
		2190	=back
		2191
		2192	Example: print the high resolution modification time of F</etc>, using
		2193	C<stat>, and C<IO::AIO::aio_stat>.
		2194
		2195	if (stat "/etc") {
		2196	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2197	}
		2198
		2199	IO::AIO::aio_stat "/etc", sub {
		2200	$_[0]
		2201	and return;
		2202
		2203	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2204	};
		2205
		2206	IO::AIO::flush;
		2207
		2208	Output of the awbove on my system, showing reduced and full accuracy:
		2209
		2210	stat(/etc) mtime: 1534043702.020808
		2211	aio_stat(/etc) mtime: 1534043702.020807792
		2212
		2213
1433	=head3 MISCELLANEOUS FUNCTIONS	2214	=head3 MISCELLANEOUS FUNCTIONS
1434		2215
1435	IO::AIO implements some functions that might be useful, but are not	2216	IO::AIO implements some functions that are useful when you want to use
1436	asynchronous.	2217	some "Advanced I/O" function not available to in Perl, without going the
		2218	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2219	counterpart.
1437		2220
1438	=over 4	2221	=over 4
		2222
		2223	=item $numfd = IO::AIO::get_fdlimit
		2224
		2225	Tries to find the current file descriptor limit and returns it, or
		2226	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2227	the highest valid file descriptor number.
		2228
		2229	=item IO::AIO::min_fdlimit [$numfd]
		2230
		2231	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2232	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2233	is missing, it will try to set a very high limit, although this is not
		2234	recommended when you know the actual minimum that you require.
		2235
		2236	If the limit cannot be raised enough, the function makes a best-effort
		2237	attempt to increase the limit as much as possible, using various
		2238	tricks, while still failing. You can query the resulting limit using
		2239	C<IO::AIO::get_fdlimit>.
		2240
		2241	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2242	true.
1439		2243
1440	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2244	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1441		2245
1442	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2246	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1443	but is blocking (this makes most sense if you know the input data is	2247	but is blocking (this makes most sense if you know the input data is
…		…
1446		2250
1447	Returns the number of bytes copied, or C<-1> on error.	2251	Returns the number of bytes copied, or C<-1> on error.
1448		2252
1449	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2253	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1450		2254
1451	Simply calls the C<posix_fadvise> function (see it's	2255	Simply calls the C<posix_fadvise> function (see its
1452	manpage for details). The following advice constants are	2256	manpage for details). The following advice constants are
1453	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2257	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1454	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2258	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1455	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2259	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1456		2260
1457	On systems that do not implement C<posix_fadvise>, this function returns	2261	On systems that do not implement C<posix_fadvise>, this function returns
1458	ENOSYS, otherwise the return value of C<posix_fadvise>.	2262	ENOSYS, otherwise the return value of C<posix_fadvise>.
1459		2263
		2264	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		2265
		2266	Simply calls the C<posix_madvise> function (see its
		2267	manpage for details). The following advice constants are
		2268	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		2269	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2270	C<IO::AIO::MADV_DONTNEED>.
		2271
		2272	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2273	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2274	will be reduced to fit into the C<$scalar>.
		2275
		2276	On systems that do not implement C<posix_madvise>, this function returns
		2277	ENOSYS, otherwise the return value of C<posix_madvise>.
		2278
		2279	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		2280
		2281	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		2282	$scalar (see its manpage for details). The following protect
		2283	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		2284	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2285
		2286	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2287	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2288	will be reduced to fit into the C<$scalar>.
		2289
		2290	On systems that do not implement C<mprotect>, this function returns
		2291	ENOSYS, otherwise the return value of C<mprotect>.
		2292
		2293	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		2294
		2295	Memory-maps a file (or anonymous memory range) and attaches it to the
		2296	given C<$scalar>, which will act like a string scalar. Returns true on
		2297	success, and false otherwise.
		2298
		2299	The scalar must exist, but its contents do not matter - this means you
		2300	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2301	the scalar first.
		2302
		2303	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
		2304	which don't change the string length, and most read-only operations such
		2305	as copying it or searching it with regexes and so on.
		2306
		2307	Anything else is unsafe and will, at best, result in memory leaks.
		2308
		2309	The memory map associated with the C<$scalar> is automatically removed
		2310	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
		2311	or C<IO::AIO::munmap> functions are called on it.
		2312
		2313	This calls the C<mmap>(2) function internally. See your system's manual
		2314	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		2315
		2316	The C<$length> must be larger than zero and smaller than the actual
		2317	filesize.
		2318
		2319	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		2320	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		2321
		2322	C<$flags> can be a combination of
		2323	C<IO::AIO::MAP_SHARED> or
		2324	C<IO::AIO::MAP_PRIVATE>,
		2325	or a number of system-specific flags (when not available, the are C<0>):
		2326	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
		2327	C<IO::AIO::MAP_LOCKED>,
		2328	C<IO::AIO::MAP_NORESERVE>,
		2329	C<IO::AIO::MAP_POPULATE>,
		2330	C<IO::AIO::MAP_NONBLOCK>,
		2331	C<IO::AIO::MAP_FIXED>,
		2332	C<IO::AIO::MAP_GROWSDOWN>,
		2333	C<IO::AIO::MAP_32BIT>,
		2334	C<IO::AIO::MAP_HUGETLB>,
		2335	C<IO::AIO::MAP_STACK>,
		2336	C<IO::AIO::MAP_FIXED_NOREPLACE>,
		2337	C<IO::AIO::MAP_SHARED_VALIDATE>,
		2338	C<IO::AIO::MAP_SYNC> or
		2339	C<IO::AIO::MAP_UNINITIALIZED>.
		2340
		2341	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		2342
		2343	C<$offset> is the offset from the start of the file - it generally must be
		2344	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		2345
		2346	Example:
		2347
		2348	use Digest::MD5;
		2349	use IO::AIO;
		2350
		2351	open my $fh, "<verybigfile"
		2352	or die "$!";
		2353
		2354	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		2355	or die "verybigfile: $!";
		2356
		2357	my $fast_md5 = md5 $data;
		2358
		2359	=item IO::AIO::munmap $scalar
		2360
		2361	Removes a previous mmap and undefines the C<$scalar>.
		2362
		2363	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2364
		2365	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2366	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2367	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2368
		2369	Returns true if successful, and false otherwise. If the underlying mmapped
		2370	region has changed address, then the true value has the numerical value
		2371	C<1>, otherwise it has the numerical value C<0>:
		2372
		2373	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2374	or die "mremap: $!";
		2375
		2376	if ($success*1) {
		2377	warn "scalar has chanegd address in memory\n";
		2378	}
		2379
		2380	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2381	implemented, but not supported and might go away in a future version.
		2382
		2383	On systems where this call is not supported or is not emulated, this call
		2384	returns falls and sets C<$!> to C<ENOSYS>.
		2385
		2386	=item IO::AIO::mlockall $flags
		2387
		2388	Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
		2389	but is blocking.
		2390
		2391	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		2392
		2393	Calls the C<munlock> function, undoing the effects of a previous
		2394	C<aio_mlock> call (see its description for details).
		2395
		2396	=item IO::AIO::munlockall
		2397
		2398	Calls the C<munlockall> function.
		2399
		2400	On systems that do not implement C<munlockall>, this function returns
		2401	ENOSYS, otherwise the return value of C<munlockall>.
		2402
		2403	=item $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		2404
		2405	Uses the GNU/Linux C<accept4(2)> syscall, if available, to accept a socket
		2406	and return the new file handle on success, or sets C<$!> and returns
		2407	C<undef> on error.
		2408
		2409	The remote name of the new socket will be stored in C<$sockaddr>, which
		2410	will be extended to allow for at least C<$sockaddr_maxlen> octets. If the
		2411	socket name does not fit into C<$sockaddr_maxlen> octets, this is signaled
		2412	by returning a longer string in C<$sockaddr>, which might or might not be
		2413	truncated.
		2414
		2415	To accept name-less sockets, use C<undef> for C<$sockaddr> and C<0> for
		2416	C<$sockaddr_maxlen>.
		2417
		2418	The main reasons to use this syscall rather than portable C<accept(2)>
		2419	are that you can specify C<SOCK_NONBLOCK> and/or C<SOCK_CLOEXEC>
		2420	flags and you can accept name-less sockets by specifying C<0> for
		2421	C<$sockaddr_maxlen>, which is sadly not possible with perl's interface to
		2422	C<accept>.
		2423
		2424	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2425
		2426	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2427	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2428	should be the file offset.
		2429
		2430	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2431	silently corrupt the data in this case.
		2432
		2433	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2434	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2435	C<IO::AIO::SPLICE_F_GIFT>.
		2436
		2437	See the C<splice(2)> manpage for details.
		2438
		2439	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2440
		2441	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2442	description for C<IO::AIO::splice> above for details.
		2443
		2444	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2445
		2446	Attempts to query or change the pipe buffer size. Obviously works only
		2447	on pipes, and currently works only on GNU/Linux systems, and fails with
		2448	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2449	size on other systems, drop me a note.
		2450
		2451	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2452
		2453	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2454	C<$flags> is missing or C<0>, then this should be the same as a call to
		2455	perl's built-in C<pipe> function and create a new pipe, and works on
		2456	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2457	(..., 4096, O_BINARY)>.
		2458
		2459	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2460	the given flags (Linux 2.6.27, glibc 2.9).
		2461
		2462	On success, the read and write file handles are returned.
		2463
		2464	On error, nothing will be returned. If the pipe2 syscall is missing and
		2465	C<$flags> is non-zero, fails with C<ENOSYS>.
		2466
		2467	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2468	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2469	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2470
		2471	Example: create a pipe race-free w.r.t. threads and fork:
		2472
		2473	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2474	or die "pipe2: $!\n";
		2475
		2476	=item $fh = IO::AIO::memfd_create $pathname[, $flags]
		2477
		2478	This is a direct interface to the Linux L<memfd_create(2)> system
		2479	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2480	should be C<IO::AIO::MFD_CLOEXEC>.
		2481
		2482	On success, the new memfd filehandle is returned, otherwise returns
		2483	C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
		2484
		2485	Please refer to L<memfd_create(2)> for more info on this call.
		2486
		2487	The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
		2488	C<IO::AIO::MFD_ALLOW_SEALING> and C<IO::AIO::MFD_HUGETLB>.
		2489
		2490	Example: create a new memfd.
		2491
		2492	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2493	or die "memfd_create: $!\n";
		2494
		2495	=item $fh = IO::AIO::pidfd_open $pid[, $flags]
		2496
		2497	This is an interface to the Linux L<pidfd_open(2)> system call. The
		2498	default for C<$flags> is C<0>.
		2499
		2500	On success, a new pidfd filehandle is returned (that is already set to
		2501	close-on-exec), otherwise returns C<undef>. If the syscall is missing,
		2502	fails with C<ENOSYS>.
		2503
		2504	Example: open pid 6341 as pidfd.
		2505
		2506	my $fh = IO::AIO::pidfd_open 6341
		2507	or die "pidfd_open: $!\n";
		2508
		2509	=item $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		2510
		2511	This is an interface to the Linux L<pidfd_send_signal> system call. The
		2512	default for C<$siginfo> is C<undef> and the default for C<$flags> is C<0>.
		2513
		2514	Returns the system call status. If the syscall is missing, fails with
		2515	C<ENOSYS>.
		2516
		2517	When specified, C<$siginfo> must be a reference to a hash with one or more
		2518	of the following members:
		2519
		2520	=over
		2521
		2522	=item code - the C<si_code> member
		2523
		2524	=item pid - the C<si_pid> member
		2525
		2526	=item uid - the C<si_uid> member
		2527
		2528	=item value_int - the C<si_value.sival_int> member
		2529
		2530	=item value_ptr - the C<si_value.sival_ptr> member, specified as an integer
		2531
1460	=back	2532	=back
1461		2533
		2534	Example: send a SIGKILL to the specified process.
		2535
		2536	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
		2537	and die "pidfd_send_signal: $!\n";
		2538
		2539	Example: send a SIGKILL to the specified process with extra data.
		2540
		2541	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
		2542	and die "pidfd_send_signal: $!\n";
		2543
		2544	=item $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		2545
		2546	This is an interface to the Linux L<pidfd_getfd> system call. The default
		2547	for C<$flags> is C<0>.
		2548
		2549	On success, returns a dup'ed copy of the target file descriptor (specified
		2550	as an integer) returned (that is already set to close-on-exec), otherwise
		2551	returns C<undef>. If the syscall is missing, fails with C<ENOSYS>.
		2552
		2553	Example: get a copy of standard error of another process and print soemthing to it.
		2554
		2555	my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
		2556	or die "pidfd_getfd: $!\n";
		2557	print $errfh "stderr\n";
		2558
		2559	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2560
		2561	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2562	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2563
		2564	On success, the new eventfd filehandle is returned, otherwise returns
		2565	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2566
		2567	Please refer to L<eventfd(2)> for more info on this call.
		2568
		2569	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2570	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2571
		2572	Example: create a new eventfd filehandle:
		2573
		2574	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2575	or die "eventfd: $!\n";
		2576
		2577	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2578
		2579	This is a direct interface to the Linux L<timerfd_create(2)> system
		2580	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2581	should be C<IO::AIO::TFD_CLOEXEC>.
		2582
		2583	On success, the new timerfd filehandle is returned, otherwise returns
		2584	C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
		2585
		2586	Please refer to L<timerfd_create(2)> for more info on this call.
		2587
		2588	The following C<$clockid> values are
		2589	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2590	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2591	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2592	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2593
		2594	The following C<$flags> values are available (Linux
		2595	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2596
		2597	Example: create a new timerfd and set it to one-second repeated alarms,
		2598	then wait for two alarms:
		2599
		2600	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2601	or die "timerfd_create: $!\n";
		2602
		2603	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2604	or die "timerfd_settime: $!\n";
		2605
		2606	for (1..2) {
		2607	8 == sysread $fh, my $buf, 8
		2608	or die "timerfd read failure\n";
		2609
		2610	printf "number of expirations (likely 1): %d\n",
		2611	unpack "Q", $buf;
		2612	}
		2613
		2614	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2615
		2616	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2617	call. Please refer to its manpage for more info on this call.
		2618
		2619	The new itimerspec is specified using two (possibly fractional) second
		2620	values, C<$new_interval> and C<$new_value>).
		2621
		2622	On success, the current interval and value are returned (as per
		2623	C<timerfd_gettime>). On failure, the empty list is returned.
		2624
		2625	The following C<$flags> values are
		2626	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2627	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2628
		2629	See C<IO::AIO::timerfd_create> for a full example.
		2630
		2631	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2632
		2633	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2634	call. Please refer to its manpage for more info on this call.
		2635
		2636	On success, returns the current values of interval and value for the given
		2637	timerfd (as potentially fractional second values). On failure, the empty
		2638	list is returned.
		2639
		2640	=back
		2641
1462	=cut	2642	=cut
1463		2643
1464	min_parallel 8;	2644	min_parallel 8;
1465		2645
1466	END { flush }	2646	END { flush }
1467		2647
1468	1;	2648	1;
1469		2649
		2650	=head1 EVENT LOOP INTEGRATION
		2651
		2652	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		2653	automatically into many event loops:
		2654
		2655	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		2656	use AnyEvent::AIO;
		2657
		2658	You can also integrate IO::AIO manually into many event loops, here are
		2659	some examples of how to do this:
		2660
		2661	# EV integration
		2662	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		2663
		2664	# Event integration
		2665	Event->io (fd => IO::AIO::poll_fileno,
		2666	poll => 'r',
		2667	cb => \&IO::AIO::poll_cb);
		2668
		2669	# Glib/Gtk2 integration
		2670	add_watch Glib::IO IO::AIO::poll_fileno,
		2671	in => sub { IO::AIO::poll_cb; 1 };
		2672
		2673	# Tk integration
		2674	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		2675	readable => \&IO::AIO::poll_cb);
		2676
		2677	# Danga::Socket integration
		2678	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		2679	\&IO::AIO::poll_cb);
		2680
1470	=head2 FORK BEHAVIOUR	2681	=head2 FORK BEHAVIOUR
1471		2682
1472	This module should do "the right thing" when the process using it forks:	2683	Usage of pthreads in a program changes the semantics of fork
		2684	considerably. Specifically, only async-safe functions can be called after
		2685	fork. Perl doesn't know about this, so in general, you cannot call fork
		2686	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2687	pthreads, so this applies, but many other extensions and (for inexplicable
		2688	reasons) perl itself often is linked against pthreads, so this limitation
		2689	applies to quite a lot of perls.
1473		2690
1474	Before the fork, IO::AIO enters a quiescent state where no requests	2691	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1475	can be added in other threads and no results will be processed. After	2692	only works in the process that loaded it. Forking is fully supported, but
1476	the fork the parent simply leaves the quiescent state and continues	2693	using IO::AIO in the child is not.
1477	request/result processing, while the child frees the request/result queue
1478	(so that the requests started before the fork will only be handled in the
1479	parent). Threads will be started on demand until the limit set in the
1480	parent process has been reached again.
1481		2694
1482	In short: the parent will, after a short pause, continue as if fork had	2695	You might get around by not I<using> IO::AIO before (or after)
1483	not been called, while the child will act as if IO::AIO has not been used	2696	forking. You could also try to call the L<IO::AIO::reinit> function in the
1484	yet.	2697	child:
		2698
		2699	=over 4
		2700
		2701	=item IO::AIO::reinit
		2702
		2703	Abandons all current requests and I/O threads and simply reinitialises all
		2704	data structures. This is not an operation supported by any standards, but
		2705	happens to work on GNU/Linux and some newer BSD systems.
		2706
		2707	The only reasonable use for this function is to call it after forking, if
		2708	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2709	the process will result in undefined behaviour. Calling it at any time
		2710	will also result in any undefined (by POSIX) behaviour.
		2711
		2712	=back
		2713
		2714	=head2 LINUX-SPECIFIC CALLS
		2715
		2716	When a call is documented as "linux-specific" then this means it
		2717	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2718	availability and compatibility of such calls regardless of the platform
		2719	it is compiled on, so platforms such as FreeBSD which often implement
		2720	these calls will work. When in doubt, call them and see if they fail wth
		2721	C<ENOSYS>.
1485		2722
1486	=head2 MEMORY USAGE	2723	=head2 MEMORY USAGE
1487		2724
1488	Per-request usage:	2725	Per-request usage:
1489		2726
…		…
1502	temporary buffers, and each thread requires a stack and other data	2739	temporary buffers, and each thread requires a stack and other data
1503	structures (usually around 16k-128k, depending on the OS).	2740	structures (usually around 16k-128k, depending on the OS).
1504		2741
1505	=head1 KNOWN BUGS	2742	=head1 KNOWN BUGS
1506		2743
1507	Known bugs will be fixed in the next release.	2744	Known bugs will be fixed in the next release :)
		2745
		2746	=head1 KNOWN ISSUES
		2747
		2748	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2749	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2750	non-created hash slots or other scalars I didn't think of. It's best to
		2751	avoid such and either use scalar variables or making sure that the scalar
		2752	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2753
		2754	I am not sure anything can be done about this, so this is considered a
		2755	known issue, rather than a bug.
1508		2756
1509	=head1 SEE ALSO	2757	=head1 SEE ALSO
1510		2758
1511	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2759	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1512	more natural syntax.	2760	more natural syntax and L<IO::FDPass> for file descriptor passing.
1513		2761
1514	=head1 AUTHOR	2762	=head1 AUTHOR
1515		2763
1516	Marc Lehmann <schmorp@schmorp.de>	2764	Marc Lehmann <schmorp@schmorp.de>
1517	http://home.schmorp.de/	2765	http://home.schmorp.de/

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