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Revision 1.156 by root, Tue Jun 16 23:41:59 2009 UTC vs.
Revision 1.313 by root, Sat Sep 4 21:21:14 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.
…		…
186		166
187	package IO::AIO;	167	package IO::AIO;
188		168
189	use Carp ();	169	use Carp ();
190		170
191	no warnings;	171	use common::sense;
192	use strict 'vars';
193		172
194	use base 'Exporter';	173	use base 'Exporter';
195		174
196	BEGIN {	175	BEGIN {
197	our $VERSION = '3.23';	176	our $VERSION = 4.76;
198		177
199	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
200	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
201	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
202	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
203	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
204	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
205	aio_chmod aio_utime aio_truncate);	185	aio_chmod aio_utime aio_truncate
		186	aio_msync aio_mtouch aio_mlock aio_mlockall
		187	aio_statvfs
		188	aio_slurp
		189	aio_wd);
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
		196	sendfile fadvise madvise
		197	mmap munmap mremap munlock munlockall);
212		198
213	push @AIO_REQ, qw(aio_busy); # not exported	199	push @AIO_REQ, qw(aio_busy); # not exported
214		200
215	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	201	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
216		202
…		…
218	XSLoader::load ("IO::AIO", $VERSION);	204	XSLoader::load ("IO::AIO", $VERSION);
219	}	205	}
220		206
221	=head1 FUNCTIONS	207	=head1 FUNCTIONS
222		208
223	=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 $fh
		318
		319	=head2 API NOTES
224		320
225	All the C<aio_*> calls are more or less thin wrappers around the syscall	321	All the C<aio_*> calls are more or less thin wrappers around the syscall
226	with the same name (sans C<aio_>). The arguments are similar or identical,	322	with the same name (sans C<aio_>). The arguments are similar or identical,
227	and they all accept an additional (and optional) C<$callback> argument	323	and they all accept an additional (and optional) C<$callback> argument
228	which must be a code reference. This code reference will get called with	324	which must be a code reference. This code reference will be called after
229	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	325	the syscall has been executed in an asynchronous fashion. The results
230	perl, which usually delivers "false") as its sole argument after the given	326	of the request will be passed as arguments to the callback (and, if an
231	syscall has been executed asynchronously.	327	error occured, in C<$!>) - 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>.
232		333
233	All functions expecting a filehandle keep a copy of the filehandle	334	All functions expecting a filehandle keep a copy of the filehandle
234	internally until the request has finished.	335	internally until the request has finished.
235		336
236	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
237	further manipulation of those requests while they are in-flight.	338	further manipulation of those requests while they are in-flight.
238		339
239	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
240	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
241	request is being executed, the current working directory could have	342	current working directory could have changed. Alternatively, you can
242	changed. Alternatively, you can make sure that you never change the	343	make sure that you never change the current working directory anywhere
243	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
244	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.
245		348
246	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
247	in filenames you got from outside (command line, readdir etc.) without	350	in filenames you got from outside (command line, readdir etc.) without
248	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
249	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
250	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
251	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.
252		356
253	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
254	handles correctly whether it is set or not.	358	handles correctly whether it is set or not.
		359
		360	=head2 AIO REQUEST FUNCTIONS
255		361
256	=over 4	362	=over 4
257		363
258	=item $prev_pri = aioreq_pri [$pri]	364	=item $prev_pri = aioreq_pri [$pri]
259		365
…		…
289		395
290		396
291	=item aio_open $pathname, $flags, $mode, $callback->($fh)	397	=item aio_open $pathname, $flags, $mode, $callback->($fh)
292		398
293	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
294	created filehandle for the file.	400	created filehandle for the file (or C<undef> in case of an error).
295		401
296	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,
297	for an explanation.	403	for an explanation.
298		404
299	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
…		…
306	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
307	change the umask.	413	change the umask.
308		414
309	Example:	415	Example:
310		416
311	aio_open "/etc/passwd", O_RDONLY, 0, sub {	417	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
312	if ($_[0]) {	418	if ($_[0]) {
313	print "open successful, fh is $_[0]\n";	419	print "open successful, fh is $_[0]\n";
314	...	420	...
315	} else {	421	} else {
316	die "open failed: $!\n";	422	die "open failed: $!\n";
317	}	423	}
318	};	424	};
319		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
320		435
321	=item aio_close $fh, $callback->($status)	436	=item aio_close $fh, $callback->($status)
322		437
323	Asynchronously close a file and call the callback with the result	438	Asynchronously close a file and call the callback with the result
324	code.	439	code.
…		…
333	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
334	free for reuse until the perl filehandle is closed.	449	free for reuse until the perl filehandle is closed.
335		450
336	=cut	451	=cut
337		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
338	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	473	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
339		474
340	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	475	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
341		476
342	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
343	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
344	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
345	error, just like the syscall).	480	error, just like the syscall).
346		481
347	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
348	offset plus the actual number of bytes read.	483	offset plus the actual number of bytes read.
349		484
…		…
374		509
375	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
376	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
377	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
378	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
379	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>.
380		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<$in_fh>) is a file - the file I/O will then be asynchronous, while
		526	the socket I/O will be non-blocking. Note, however, that you can run
		527	into a trap where C<aio_sendfile> reads some data with readahead, then
		528	fails to write all data, and when the socket is ready the next time, the
		529	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		530	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		531	resource usage.
		532
381	This call tries to make use of a native C<sendfile> syscall to provide	533	This call tries to make use of a native C<sendfile>-like syscall to
382	zero-copy operation. For this to work, C<$out_fh> should refer to a	534	provide zero-copy operation. For this to work, C<$out_fh> should refer to
383	socket, and C<$in_fh> should refer to mmap'able file.	535	a socket, and C<$in_fh> should refer to an mmap'able file.
384		536
385	If the native sendfile call fails or is not implemented, it will be	537	If a native sendfile cannot be found or it fails with C<ENOSYS>,
386	emulated, so you can call C<aio_sendfile> on any type of filehandle	538	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		539	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
387	regardless of the limitations of the operating system.	540	type of filehandle regardless of the limitations of the operating system.
388		541
389	Please note, however, that C<aio_sendfile> can read more bytes from	542	As native sendfile syscalls (as practically any non-POSIX interface hacked
390	C<$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
391	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
392	provides the number of bytes written to C<$out_fh>. Only if the result	545	in Linux and FreeBSD kernels (probably others, too), but that might fail,
393	value equals C<$length> one can assume that C<$length> bytes have been	546	so you really really should check the return value of C<aio_sendfile> -
394	read.	547	fewer bytes than expected might have been transferred.
395		548
396		549
397	=item aio_readahead $fh,$offset,$length, $callback->($retval)	550	=item aio_readahead $fh,$offset,$length, $callback->($retval)
398		551
399	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
…		…
403	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
404	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
405	(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
406	file. The current file offset of the file is left unchanged.	559	file. The current file offset of the file is left unchanged.
407		560
408	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
409	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.
410		563
411		564
412	=item aio_stat $fh_or_path, $callback->($status)	565	=item aio_stat $fh_or_path, $callback->($status)
413		566
414	=item aio_lstat $fh, $callback->($status)	567	=item aio_lstat $fh, $callback->($status)
415		568
416	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
417	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
418	or C<-s _> etc...	571	using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
		572	and C<-T>).
419		573
420	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,
421	for an explanation.	575	for an explanation.
422		576
423	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
424	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
425	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>.
426		592
427	Example: Print the length of F</etc/passwd>:	593	Example: Print the length of F</etc/passwd>:
428		594
429	aio_stat "/etc/passwd", sub {	595	aio_stat "/etc/passwd", sub {
430	$_[0] and die "stat failed: $!";	596	$_[0] and die "stat failed: $!";
431	print "size is ", -s _, "\n";	597	print "size is ", -s _, "\n";
432	};	598	};
433		599
434		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
435	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	645	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
436		646
437	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
438	and $mtime being undef). Fractional times are supported if the underlying	648	and $mtime being undef). Fractional times are supported if the underlying
439	syscalls support them.	649	syscalls support them.
440		650
441	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,
442	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)
443	otherwise returns ENOSYS, so this is not portable.	653	or futimes(2) if available, otherwise returns ENOSYS, so this is not
		654	portable.
444		655
445	Examples:	656	Examples:
446		657
447	# set atime and mtime to current time (basically touch(1)):	658	# set atime and mtime to current time (basically touch(1)):
448	aio_utime "path", undef, undef;	659	aio_utime "path", undef, undef;
…		…
466	=item aio_truncate $fh_or_path, $offset, $callback->($status)	677	=item aio_truncate $fh_or_path, $offset, $callback->($status)
467		678
468	Works like truncate(2) or ftruncate(2).	679	Works like truncate(2) or ftruncate(2).
469		680
470		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
471	=item aio_chmod $fh_or_path, $mode, $callback->($status)	704	=item aio_chmod $fh_or_path, $mode, $callback->($status)
472		705
473	Works like perl's C<chmod> function.	706	Works like perl's C<chmod> function.
474		707
475		708
…		…
477		710
478	Asynchronously unlink (delete) a file and call the callback with the	711	Asynchronously unlink (delete) a file and call the callback with the
479	result code.	712	result code.
480		713
481		714
482	=item aio_mknod $path, $mode, $dev, $callback->($status)	715	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
483		716
484	[EXPERIMENTAL]	717	[EXPERIMENTAL]
485		718
486	Asynchronously create a device node (or fifo). See mknod(2).	719	Asynchronously create a device node (or fifo). See mknod(2).
487		720
488	The only (POSIX-) portable way of calling this function is:	721	The only (POSIX-) portable way of calling this function is:
489		722
490	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	723	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
491		724
		725	See C<aio_stat> for info about some potentially helpful extra constants
		726	and functions.
492		727
493	=item aio_link $srcpath, $dstpath, $callback->($status)	728	=item aio_link $srcpath, $dstpath, $callback->($status)
494		729
495	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
496	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.
…		…
500		735
501	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
502	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.
503		738
504		739
505	=item aio_readlink $path, $callback->($link)	740	=item aio_readlink $pathname, $callback->($link)
506		741
507	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
508	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
509	callback.	744	callback.
510		745
511		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
512	=item aio_rename $srcpath, $dstpath, $callback->($status)	757	=item aio_rename $srcpath, $dstpath, $callback->($status)
513		758
514	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
515	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>.
516		781
517		782
518	=item aio_mkdir $pathname, $mode, $callback->($status)	783	=item aio_mkdir $pathname, $mode, $callback->($status)
519		784
520	Asynchronously mkdir (create) a directory and call the callback with	785	Asynchronously mkdir (create) a directory and call the callback with
…		…
525	=item aio_rmdir $pathname, $callback->($status)	790	=item aio_rmdir $pathname, $callback->($status)
526		791
527	Asynchronously rmdir (delete) a directory and call the callback with the	792	Asynchronously rmdir (delete) a directory and call the callback with the
528	result code.	793	result code.
529		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
530		799
531	=item aio_readdir $pathname, $callback->($entries)	800	=item aio_readdir $pathname, $callback->($entries)
532		801
533	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
534	directory (i.e. opendir + readdir + closedir). The entries will not be	803	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
538	array-ref with the filenames.	807	array-ref with the filenames.
539		808
540		809
541	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	810	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
542		811
543	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	812	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
544	behaviour and output format. In case of an error, C<$entries> will be	813	tune behaviour and output format. In case of an error, C<$entries> will be
545	C<undef>.	814	C<undef>.
546		815
547	The flags are a combination of the following constants, ORed together (the	816	The flags are a combination of the following constants, ORed together (the
548	flags will also be passed to the callback, possibly modified):	817	flags will also be passed to the callback, possibly modified):
549		818
550	=over 4	819	=over 4
551		820
552	=item IO::AIO::READDIR_DENTS	821	=item IO::AIO::READDIR_DENTS
553		822
554	When this flag is off, then the callback gets an arrayref with of names	823	Normally the callback gets an arrayref consisting of names only (as
555	only (as with C<aio_readdir>), otherwise it gets an arrayref with	824	with C<aio_readdir>). If this flag is set, then the callback gets an
556	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	825	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
557	entry in more detail.	826	single directory entry in more detail:
558		827
559	C<$name> is the name of the entry.	828	C<$name> is the name of the entry.
560		829
561	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	830	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
562		831
563	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	832	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
564	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	833	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
565	C<IO::AIO::DT_WHT>.	834	C<IO::AIO::DT_WHT>.
566		835
567	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	836	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
568	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	837	to know, you have to run stat yourself. Also, for speed/memory reasons,
569	scalars are read-only: you can not modify them.	838	the C<$type> scalars are read-only: you must not modify them.
570		839
571	C<$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
572	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
573	systems that do not deliver the inode information.	842	systems that do not deliver the inode information.
574		843
575	=item IO::AIO::READDIR_DIRS_FIRST	844	=item IO::AIO::READDIR_DIRS_FIRST
576		845
577	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
578	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
579	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
580	stat() each entry.	849	while avoiding to stat() each entry.
581		850
582	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
583	to find directories directly. Otherwise, likely directories are files	852	to find directories directly. Otherwise, likely directories are names
584	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
585	short names are tried first.	854	short names are tried first.
586		855
587	=item IO::AIO::READDIR_STAT_ORDER	856	=item IO::AIO::READDIR_STAT_ORDER
588		857
589	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
590	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
591	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
592	be fastest.	861	faster.
593		862
594	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,
595	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.
596		867
597	=item IO::AIO::READDIR_FOUND_UNKNOWN	868	=item IO::AIO::READDIR_FOUND_UNKNOWN
598		869
599	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
600	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<$type>'s found were
601	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	872	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
602	C<$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.
603		874
604	=back	875	=back
605		876
606		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
607	=item aio_load $path, $data, $callback->($status)	907	=item aio_load $pathname, $data, $callback->($status)
608		908
609	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
610	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.
611		913
612	=cut	914	=cut
613		915
614	sub aio_load($$;$) {	916	sub aio_load($$;$) {
615	my ($path, undef, $cb) = @_;	917	my ($path, undef, $cb) = @_;
…		…
634		936
635	=item aio_copy $srcpath, $dstpath, $callback->($status)	937	=item aio_copy $srcpath, $dstpath, $callback->($status)
636		938
637	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
638	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
639	the C<0> (error) or C<-1> ok.	941	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		942
		943	Existing destination files will be truncated.
640		944
641	This is a composite request that creates the destination file with	945	This is a composite request that creates the destination file with
642	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
643	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	947	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
644	uid/gid, in that order.	948	uid/gid, in that order.
…		…
656	my $grp = aio_group $cb;	960	my $grp = aio_group $cb;
657		961
658	aioreq_pri $pri;	962	aioreq_pri $pri;
659	add $grp aio_open $src, O_RDONLY, 0, sub {	963	add $grp aio_open $src, O_RDONLY, 0, sub {
660	if (my $src_fh = $_[0]) {	964	if (my $src_fh = $_[0]) {
661	my @stat = stat $src_fh; # hmm, might bock over nfs?	965	my @stat = stat $src_fh; # hmm, might block over nfs?
662		966
663	aioreq_pri $pri;	967	aioreq_pri $pri;
664	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	968	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
665	if (my $dst_fh = $_[0]) {	969	if (my $dst_fh = $_[0]) {
666	aioreq_pri $pri;	970	aioreq_pri $pri;
…		…
713		1017
714	=item aio_move $srcpath, $dstpath, $callback->($status)	1018	=item aio_move $srcpath, $dstpath, $callback->($status)
715		1019
716	Try to move the I<file> (directories not supported as either source or	1020	Try to move the I<file> (directories not supported as either source or
717	destination) from C<$srcpath> to C<$dstpath> and call the callback with	1021	destination) from C<$srcpath> to C<$dstpath> and call the callback with
718	the C<0> (error) or C<-1> ok.	1022	a status of C<0> (ok) or C<-1> (error, see C<$!>).
719		1023
720	This is a composite request that tries to rename(2) the file first; if	1024	This is a composite request that tries to rename(2) the file first; if
721	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if	1025	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
722	that is successful, unlinks the C<$srcpath>.	1026	that is successful, unlinks the C<$srcpath>.
723		1027
…		…
734	if ($_[0] && $! == EXDEV) {	1038	if ($_[0] && $! == EXDEV) {
735	aioreq_pri $pri;	1039	aioreq_pri $pri;
736	add $grp aio_copy $src, $dst, sub {	1040	add $grp aio_copy $src, $dst, sub {
737	$grp->result ($_[0]);	1041	$grp->result ($_[0]);
738		1042
739	if (!$_[0]) {	1043	unless ($_[0]) {
740	aioreq_pri $pri;	1044	aioreq_pri $pri;
741	add $grp aio_unlink $src;	1045	add $grp aio_unlink $src;
742	}	1046	}
743	};	1047	};
744	} else {	1048	} else {
…		…
747	};	1051	};
748		1052
749	$grp	1053	$grp
750	}	1054	}
751		1055
752	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1056	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
753		1057
754	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1058	Scans a directory (similar to C<aio_readdir>) but additionally tries to
755	efficiently separate the entries of directory C<$path> into two sets of	1059	efficiently separate the entries of directory C<$path> into two sets of
756	names, directories you can recurse into (directories), and ones you cannot	1060	names, directories you can recurse into (directories), and ones you cannot
757	recurse into (everything else, including symlinks to directories).	1061	recurse into (everything else, including symlinks to directories).
758		1062
759	C<aio_scandir> is a composite request that creates of many sub requests_	1063	C<aio_scandir> is a composite request that generates many sub requests.
760	C<$maxreq> specifies the maximum number of outstanding aio requests that	1064	C<$maxreq> specifies the maximum number of outstanding aio requests that
761	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
762	will be chosen (currently 4).	1066	will be chosen (currently 4).
763		1067
764	On error, the callback is called without arguments, otherwise it receives	1068	On error, the callback is called without arguments, otherwise it receives
…		…
788	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
789	currently) and likely non-directories (see C<aio_readdirx>). Then every	1093	currently) and likely non-directories (see C<aio_readdirx>). Then every
790	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,
791	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
792	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
793	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
794	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
795	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
796	the filetype information on readdir.	1100	the filetype information on readdir.
797		1101
798	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
…		…
814		1118
815	my $grp = aio_group $cb;	1119	my $grp = aio_group $cb;
816		1120
817	$maxreq = 4 if $maxreq <= 0;	1121	$maxreq = 4 if $maxreq <= 0;
818		1122
819	# stat once	1123	# get a wd object
820	aioreq_pri $pri;	1124	aioreq_pri $pri;
821	add $grp aio_stat $path, sub {	1125	add $grp aio_wd $path, sub {
		1126	$_[0]
822	return $grp->result () if $_[0];	1127	or return $grp->result ();
823	my $now = time;
824	my $hash1 = join ":", (stat _)[0,1,3,7,9];
825		1128
826	# read the directory entries	1129	my $wd = [shift, "."];
		1130
		1131	# stat once
827	aioreq_pri $pri;	1132	aioreq_pri $pri;
828	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1133	add $grp aio_stat $wd, sub {
829	my $entries = shift
830	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;
831		1138
832	# 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
833	aioreq_pri $pri;	1147	aioreq_pri $pri;
834	add $grp aio_stat $path, sub {	1148	add $grp aio_readdirx $wd, $rdxflags, sub {
835	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1149	my ($entries, $flags) = @_
		1150	or return $grp->result ();
836		1151
		1152	if ($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
837	my $ndirs;	1167	my $dirs;
838		1168
839	# take the slow route if anything looks fishy
840	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
841	$ndirs = -1;
842	} else {
843	# if nlink == 2, we are finished
844	# for non-posix-fs's, we rely on nlink < 2
845	$ndirs = (stat _)[3] - 2
846	or return $grp->result ([], $entries);
847	}
848
849	my (@dirs, @nondirs);
850
851	my $statgrp = add $grp aio_group sub {
852	$grp->result (\@dirs, \@nondirs);
853	};
854
855	limit $statgrp $maxreq;
856	feed $statgrp sub {
857	return unless @$entries;
858	my $entry = shift @$entries;
859
860	aioreq_pri $pri;
861	add $statgrp aio_stat "$path/$entry/.", sub {
862	if ($_[0] < 0) {	1169	if (@$entries) {
863	push @nondirs, $entry;	1170	for (0 .. $#$entries) {
864	} else {	1171	if ($entries->[$_][1] != DT_DIR) {
865	# need to check for real directory	1172	# splice out directories
866	aioreq_pri $pri;	1173	$dirs = [splice @$entries, 0, $_];
867	add $statgrp aio_lstat "$path/$entry", sub {
868	if (-d _) {
869	push @dirs, $entry;
870
871	unless (--$ndirs) {
872	push @nondirs, @$entries;
873	feed $statgrp;
874	}	1174	last;
875	} else {
876	push @nondirs, $entry;
877	}	1175	}
878	}	1176	}
		1177
		1178	# if we didn't find any non-dir, then all entries are dirs
		1179	unless ($dirs) {
		1180	($dirs, $entries) = ($entries, []);
		1181	}
		1182	} else {
		1183	# directory is empty, so there are no sbdirs
		1184	$dirs = [];
879	}	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	};
880	};	1251	};
881	};	1252	};
882	};	1253	};
883	};	1254	};
884	};	1255	};
885		1256
886	$grp	1257	$grp
887	}	1258	}
888		1259
889	=item aio_rmtree $path, $callback->($status)	1260	=item aio_rmtree $pathname, $callback->($status)
890		1261
891	Delete a directory tree starting (and including) C<$path>, return the	1262	Delete a directory tree starting (and including) C<$path>, return the
892	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
893	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
894	everything else.	1265	everything else.
895		1266
896	=cut	1267	=cut
897		1268
…		…
919	};	1290	};
920		1291
921	$grp	1292	$grp
922	}	1293	}
923		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
924	=item aio_sync $callback->($status)	1343	=item aio_sync $callback->($status)
925		1344
926	Asynchronously call sync and call the callback when finished.	1345	Asynchronously call sync and call the callback when finished.
927		1346
928	=item aio_fsync $fh, $callback->($status)	1347	=item aio_fsync $fh, $callback->($status)
…		…
935	Asynchronously call fdatasync on the given filehandle and call the	1354	Asynchronously call fdatasync on the given filehandle and call the
936	callback with the fdatasync result code.	1355	callback with the fdatasync result code.
937		1356
938	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
939	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.
940		1366
941	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1367	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
942		1368
943	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>
944	to disk (but NOT the metadata), by calling the Linux-specific	1370	to disk (but NOT the metadata), by calling the Linux-specific
…		…
948	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>,
949	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1375	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
950	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
951	manpage for details.	1377	manpage for details.
952		1378
953	=item aio_pathsync $path, $callback->($status)	1379	=item aio_pathsync $pathname, $callback->($status)
954		1380
955	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
956	composite request intended to sync directories after directory operations	1382	composite request intended to sync directories after directory operations
957	(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
958	specific effect, but usually it makes sure that directory changes get	1384	specific effect, but usually it makes sure that directory changes get
959	written to disc. It works for anything that can be opened for read-only,	1385	written to disc. It works for anything that can be opened for read-only,
960	not just directories.	1386	not just directories.
		1387
		1388	Future versions of this function might fall back to other methods when
		1389	C<fsync> on the directory fails (such as calling C<sync>).
961		1390
962	Passes C<0> when everything went ok, and C<-1> on error.	1391	Passes C<0> when everything went ok, and C<-1> on error.
963		1392
964	=cut	1393	=cut
965		1394
…		…
986	};	1415	};
987		1416
988	$grp	1417	$grp
989	}	1418	}
990		1419
		1420	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
		1421
		1422	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		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
		1425	scalar must only be modified in-place while an aio operation is pending on
		1426	it).
		1427
		1428	It calls the C<msync> function of your OS, if available, with the memory
		1429	area starting at C<$offset> in the string and ending C<$length> bytes
		1430	later. If C<$length> is negative, counts from the end, and if C<$length>
		1431	is C<undef>, then it goes till the end of the string. The flags can be
		1432	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
		1433	C<IO::AIO::MS_INVALIDATE>.
		1434
		1435	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1436
		1437	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1438	scalars.
		1439
		1440	It touches (reads or writes) all memory pages in the specified
		1441	range inside the scalar. All caveats and parameters are the same
		1442	as for C<aio_msync>, above, except for flags, which must be either
		1443	C<0> (which reads all pages and ensures they are instantiated) or
		1444	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
		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>.
		1534
991	=item aio_group $callback->(...)	1535	=item aio_group $callback->(...)
992		1536
993	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
994	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
995	many requests into a single, composite, request with a definite callback	1539	many requests into a single, composite, request with a definite callback
…		…
1031	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
1032	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
1033	except to put your application under artificial I/O pressure.	1577	except to put your application under artificial I/O pressure.
1034		1578
1035	=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.
1036		1705
1037	=head2 IO::AIO::REQ CLASS	1706	=head2 IO::AIO::REQ CLASS
1038		1707
1039	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
1040	called in non-void context.	1709	called in non-void context.
…		…
1130	=item $grp->cancel_subs	1799	=item $grp->cancel_subs
1131		1800
1132	Cancel all subrequests and clears any feeder, but not the group request	1801	Cancel all subrequests and clears any feeder, but not the group request
1133	itself. Useful when you queued a lot of events but got a result early.	1802	itself. Useful when you queued a lot of events but got a result early.
1134		1803
		1804	The group request will finish normally (you cannot add requests to the
		1805	group).
		1806
1135	=item $grp->result (...)	1807	=item $grp->result (...)
1136		1808
1137	Set the result value(s) that will be passed to the group callback when all	1809	Set the result value(s) that will be passed to the group callback when all
1138	subrequests have finished and set the groups errno to the current value	1810	subrequests have finished and set the groups errno to the current value
1139	of errno (just like calling C<errno> without an error number). By default,	1811	of errno (just like calling C<errno> without an error number). By default,
…		…
1155		1827
1156	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
1157	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,
1158	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,
1159	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,
1160	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>
1161	delaying any later requests for a long time.	1833	requests, delaying any later requests for a long time.
1162		1834
1163	To avoid this, and allow incremental generation of requests, you can	1835	To avoid this, and allow incremental generation of requests, you can
1164	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
1165	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>,
1166	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
…		…
1198	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
1199	automatically bumps it up to C<2>.	1871	automatically bumps it up to C<2>.
1200		1872
1201	=back	1873	=back
1202		1874
		1875
1203	=head2 SUPPORT FUNCTIONS	1876	=head2 SUPPORT FUNCTIONS
1204		1877
1205	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1878	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1206		1879
1207	=over 4	1880	=over 4
…		…
1215		1888
1216	See C<poll_cb> for an example.	1889	See C<poll_cb> for an example.
1217		1890
1218	=item IO::AIO::poll_cb	1891	=item IO::AIO::poll_cb
1219		1892
1220	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
1221	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
1222	returned earlier for whatever reason. Returns immediately when no events	1895	this "regularly" to finish outstanding requests.
1223	are outstanding. The amount of events processed depends on the settings of
1224	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1225		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
1226	If not all requests were processed for whatever reason, the filehandle	1903	If not all requests were processed for whatever reason, the poll file
1227	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
1228	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.
1229		1913
1230	Example: Install an Event watcher that automatically calls	1914	Example: Install an Event watcher that automatically calls
1231	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
1232	SYNOPSIS section, at the top of this document):	1916	SYNOPSIS section, at the top of this document):
1233		1917
1234	Event->io (fd => IO::AIO::poll_fileno,	1918	Event->io (fd => IO::AIO::poll_fileno,
1235	poll => 'r', async => 1,	1919	poll => 'r', async => 1,
1236	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
1237		1959
1238	=item IO::AIO::max_poll_reqs $nreqs	1960	=item IO::AIO::max_poll_reqs $nreqs
1239		1961
1240	=item IO::AIO::max_poll_time $seconds	1962	=item IO::AIO::max_poll_time $seconds
1241		1963
…		…
1266	# use a low priority so other tasks have priority	1988	# use a low priority so other tasks have priority
1267	Event->io (fd => IO::AIO::poll_fileno,	1989	Event->io (fd => IO::AIO::poll_fileno,
1268	poll => 'r', nice => 1,	1990	poll => 'r', nice => 1,
1269	cb => &IO::AIO::poll_cb);	1991	cb => &IO::AIO::poll_cb);
1270		1992
1271	=item IO::AIO::poll_wait
1272
1273	If there are any outstanding requests and none of them in the result
1274	phase, wait till the result filehandle becomes ready for reading (simply
1275	does a C<select> on the filehandle. This is useful if you want to
1276	synchronously wait for some requests to finish).
1277
1278	See C<nreqs> for an example.
1279
1280	=item IO::AIO::poll
1281
1282	Waits until some requests have been handled.
1283
1284	Returns the number of requests processed, but is otherwise strictly
1285	equivalent to:
1286
1287	IO::AIO::poll_wait, IO::AIO::poll_cb
1288
1289	=item IO::AIO::flush
1290
1291	Wait till all outstanding AIO requests have been handled.
1292
1293	Strictly equivalent to:
1294
1295	IO::AIO::poll_wait, IO::AIO::poll_cb
1296	while IO::AIO::nreqs;
1297
1298	=back	1993	=back
		1994
1299		1995
1300	=head3 CONTROLLING THE NUMBER OF THREADS	1996	=head3 CONTROLLING THE NUMBER OF THREADS
1301		1997
1302	=over	1998	=over
1303		1999
…		…
1335		2031
1336	Under normal circumstances you don't need to call this function.	2032	Under normal circumstances you don't need to call this function.
1337		2033
1338	=item IO::AIO::max_idle $nthreads	2034	=item IO::AIO::max_idle $nthreads
1339		2035
1340	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	2036	Limit the number of threads (default: 4) that are allowed to idle
1341	threads that did not get a request to process within 10 seconds). That	2037	(i.e., threads that did not get a request to process within the idle
1342	means if a thread becomes idle while C<$nthreads> other threads are also	2038	timeout (default: 10 seconds). That means if a thread becomes idle while
1343	idle, it will free its resources and exit.	2039	C<$nthreads> other threads are also idle, it will free its resources and
		2040	exit.
1344		2041
1345	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)
1346	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
1347	under normal circumstances (1000 threads can easily consume 30MB of RAM).	2044	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1348		2045
1349	The default is probably ok in most situations, especially if thread	2046	The default is probably ok in most situations, especially if thread
1350	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
1351	want to use larger values.	2048	want to use larger values.
1352		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
1353	=item IO::AIO::max_outstanding $maxreqs	2055	=item IO::AIO::max_outstanding $maxreqs
1354		2056
1355	This is a very bad function to use in interactive programs because it
1356	blocks, and a bad way to reduce concurrency because it is inexact: Better
1357	use an C<aio_group> together with a feed callback.
1358
1359	Sets the maximum number of outstanding requests to C<$nreqs>. If you	2057	Sets the maximum number of outstanding requests to C<$nreqs>. If
1360	do queue up more than this number of requests, the next call to the	2058	you do queue up more than this number of requests, the next call to
1361	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)	2059	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
1362	function will block until the limit is no longer exceeded.	2060	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		2061	longer exceeded.
1363		2062
1364	The default value is very large, so there is no practical limit on the	2063	In other words, this setting does not enforce a queue limit, but can be
1365	number of outstanding requests.	2064	used to make poll functions block if the limit is exceeded.
1366		2065
1367	You can still queue as many requests as you want. Therefore,	2066	This is a bad function to use in interactive programs because it blocks,
1368	C<max_outstanding> is mainly useful in simple scripts (with low values) or	2067	and a bad way to reduce concurrency because it is inexact. If you need to
1369	as a stop gap to shield against fatal memory overflow (with large values).	2068	issue many requests without being able to call a poll function on demand,
		2069	it is better to use an C<aio_group> together with a feed callback.
		2070
		2071	Its main use is in scripts without an event loop - when you want to stat a
		2072	lot of files, you can write something like this:
		2073
		2074	IO::AIO::max_outstanding 32;
		2075
		2076	for my $path (...) {
		2077	aio_stat $path , ...;
		2078	IO::AIO::poll_cb;
		2079	}
		2080
		2081	IO::AIO::flush;
		2082
		2083	The call to C<poll_cb> inside the loop will normally return instantly,
		2084	allowing the loop to progress, but as soon as more than C<32> requests
		2085	are in-flight, it will block until some requests have been handled. This
		2086	keeps the loop from pushing a large number of C<aio_stat> requests onto
		2087	the queue (which, with many paths to stat, can use up a lot of memory).
		2088
		2089	The default value for C<max_outstanding> is very large, so there is no
		2090	practical limit on the number of outstanding requests.
1370		2091
1371	=back	2092	=back
		2093
1372		2094
1373	=head3 STATISTICAL INFORMATION	2095	=head3 STATISTICAL INFORMATION
1374		2096
1375	=over	2097	=over
1376		2098
…		…
1394	Returns the number of requests currently in the pending state (executed,	2116	Returns the number of requests currently in the pending state (executed,
1395	but not yet processed by poll_cb).	2117	but not yet processed by poll_cb).
1396		2118
1397	=back	2119	=back
1398		2120
		2121
		2122	=head3 SUBSECOND STAT TIME ACCESS
		2123
		2124	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2125	generally find access/modification and change times with subsecond time
		2126	accuracy of the system supports it, but perl's built-in functions only
		2127	return the integer part.
		2128
		2129	The following functions return the timestamps of the most recent
		2130	stat with subsecond precision on most systems and work both after
		2131	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2132	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2133	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2134
		2135	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2136	full resolution without rounding and work with standard perl C<stat>,
		2137	alleviating the need to call the special C<Time::HiRes> functions, which
		2138	do not act like their perl counterparts.
		2139
		2140	On operating systems or file systems where subsecond time resolution is
		2141	not supported or could not be detected, a fractional part of C<0> is
		2142	returned, so it is always safe to call these functions.
		2143
		2144	=over 4
		2145
		2146	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		2147
		2148	Return the access, modication, change or birth time, respectively,
		2149	including fractional part. Due to the limited precision of floating point,
		2150	the accuracy on most platforms is only a bit better than milliseconds
		2151	for times around now - see the I<nsec> function family, below, for full
		2152	accuracy.
		2153
		2154	File birth time is only available when the OS and perl support it (on
		2155	FreeBSD and NetBSD at the time of this writing, although support is
		2156	adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
		2157	it). On systems where it isn't available, C<0> is currently returned, but
		2158	this might change to C<undef> in a future version.
		2159
		2160	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		2161
		2162	Returns access, modification, change and birth time all in one go, and
		2163	maybe more times in the future version.
		2164
		2165	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		2166
		2167	Return the fractional access, modifcation, change or birth time, in nanoseconds,
		2168	as an integer in the range C<0> to C<999999999>.
		2169
		2170	Note that no accessors are provided for access, modification and
		2171	change times - you need to get those from C<stat _> if required (C<int
		2172	IO::AIO::st_atime> and so on will I<not> generally give you the correct
		2173	value).
		2174
		2175	=item $seconds = IO::AIO::st_btimesec
		2176
		2177	The (integral) seconds part of the file birth time, if available.
		2178
		2179	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		2180
		2181	Like the functions above, but returns all four times in one go (and maybe
		2182	more in future versions).
		2183
		2184	=item $counter = IO::AIO::st_gen
		2185
		2186	Returns the generation counter (in practice this is just a random number)
		2187	of the file. This is only available on platforms which have this member in
		2188	their C<struct stat> (most BSDs at the time of this writing) and generally
		2189	only to the root usert. If unsupported, C<0> is returned, but this might
		2190	change to C<undef> in a future version.
		2191
		2192	=back
		2193
		2194	Example: print the high resolution modification time of F</etc>, using
		2195	C<stat>, and C<IO::AIO::aio_stat>.
		2196
		2197	if (stat "/etc") {
		2198	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2199	}
		2200
		2201	IO::AIO::aio_stat "/etc", sub {
		2202	$_[0]
		2203	and return;
		2204
		2205	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2206	};
		2207
		2208	IO::AIO::flush;
		2209
		2210	Output of the awbove on my system, showing reduced and full accuracy:
		2211
		2212	stat(/etc) mtime: 1534043702.020808
		2213	aio_stat(/etc) mtime: 1534043702.020807792
		2214
		2215
		2216	=head3 MISCELLANEOUS FUNCTIONS
		2217
		2218	IO::AIO implements some functions that are useful when you want to use
		2219	some "Advanced I/O" function not available to in Perl, without going the
		2220	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2221	counterpart.
		2222
		2223	=over 4
		2224
		2225	=item $numfd = IO::AIO::get_fdlimit
		2226
		2227	Tries to find the current file descriptor limit and returns it, or
		2228	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2229	the highest valid file descriptor number.
		2230
		2231	=item IO::AIO::min_fdlimit [$numfd]
		2232
		2233	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2234	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2235	is missing, it will try to set a very high limit, although this is not
		2236	recommended when you know the actual minimum that you require.
		2237
		2238	If the limit cannot be raised enough, the function makes a best-effort
		2239	attempt to increase the limit as much as possible, using various
		2240	tricks, while still failing. You can query the resulting limit using
		2241	C<IO::AIO::get_fdlimit>.
		2242
		2243	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2244	true.
		2245
		2246	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		2247
		2248	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		2249	but is blocking (this makes most sense if you know the input data is
		2250	likely cached already and the output filehandle is set to non-blocking
		2251	operations).
		2252
		2253	Returns the number of bytes copied, or C<-1> on error.
		2254
		2255	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		2256
		2257	Simply calls the C<posix_fadvise> function (see its
		2258	manpage for details). The following advice constants are
		2259	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		2260	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		2261	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		2262
		2263	On systems that do not implement C<posix_fadvise>, this function returns
		2264	ENOSYS, otherwise the return value of C<posix_fadvise>.
		2265
		2266	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		2267
		2268	Simply calls the C<posix_madvise> function (see its
		2269	manpage for details). The following advice constants are
		2270	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		2271	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2272	C<IO::AIO::MADV_DONTNEED>.
		2273
		2274	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2275	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2276	will be reduced to fit into the C<$scalar>.
		2277
		2278	On systems that do not implement C<posix_madvise>, this function returns
		2279	ENOSYS, otherwise the return value of C<posix_madvise>.
		2280
		2281	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		2282
		2283	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		2284	$scalar (see its manpage for details). The following protect
		2285	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		2286	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2287
		2288	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2289	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2290	will be reduced to fit into the C<$scalar>.
		2291
		2292	On systems that do not implement C<mprotect>, this function returns
		2293	ENOSYS, otherwise the return value of C<mprotect>.
		2294
		2295	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		2296
		2297	Memory-maps a file (or anonymous memory range) and attaches it to the
		2298	given C<$scalar>, which will act like a string scalar. Returns true on
		2299	success, and false otherwise.
		2300
		2301	The scalar must exist, but its contents do not matter - this means you
		2302	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2303	the scalar first.
		2304
		2305	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
		2306	which don't change the string length, and most read-only operations such
		2307	as copying it or searching it with regexes and so on.
		2308
		2309	Anything else is unsafe and will, at best, result in memory leaks.
		2310
		2311	The memory map associated with the C<$scalar> is automatically removed
		2312	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
		2313	or C<IO::AIO::munmap> functions are called on it.
		2314
		2315	This calls the C<mmap>(2) function internally. See your system's manual
		2316	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		2317
		2318	The C<$length> must be larger than zero and smaller than the actual
		2319	filesize.
		2320
		2321	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		2322	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		2323
		2324	C<$flags> can be a combination of
		2325	C<IO::AIO::MAP_SHARED> or
		2326	C<IO::AIO::MAP_PRIVATE>,
		2327	or a number of system-specific flags (when not available, the are C<0>):
		2328	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
		2329	C<IO::AIO::MAP_LOCKED>,
		2330	C<IO::AIO::MAP_NORESERVE>,
		2331	C<IO::AIO::MAP_POPULATE>,
		2332	C<IO::AIO::MAP_NONBLOCK>,
		2333	C<IO::AIO::MAP_FIXED>,
		2334	C<IO::AIO::MAP_GROWSDOWN>,
		2335	C<IO::AIO::MAP_32BIT>,
		2336	C<IO::AIO::MAP_HUGETLB>,
		2337	C<IO::AIO::MAP_STACK>,
		2338	C<IO::AIO::MAP_FIXED_NOREPLACE>,
		2339	C<IO::AIO::MAP_SHARED_VALIDATE>,
		2340	C<IO::AIO::MAP_SYNC> or
		2341	C<IO::AIO::MAP_UNINITIALIZED>.
		2342
		2343	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		2344
		2345	C<$offset> is the offset from the start of the file - it generally must be
		2346	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		2347
		2348	Example:
		2349
		2350	use Digest::MD5;
		2351	use IO::AIO;
		2352
		2353	open my $fh, "<verybigfile"
		2354	or die "$!";
		2355
		2356	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		2357	or die "verybigfile: $!";
		2358
		2359	my $fast_md5 = md5 $data;
		2360
		2361	=item IO::AIO::munmap $scalar
		2362
		2363	Removes a previous mmap and undefines the C<$scalar>.
		2364
		2365	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2366
		2367	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2368	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2369	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2370
		2371	Returns true if successful, and false otherwise. If the underlying mmapped
		2372	region has changed address, then the true value has the numerical value
		2373	C<1>, otherwise it has the numerical value C<0>:
		2374
		2375	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2376	or die "mremap: $!";
		2377
		2378	if ($success*1) {
		2379	warn "scalar has chanegd address in memory\n";
		2380	}
		2381
		2382	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2383	implemented, but not supported and might go away in a future version.
		2384
		2385	On systems where this call is not supported or is not emulated, this call
		2386	returns falls and sets C<$!> to C<ENOSYS>.
		2387
		2388	=item IO::AIO::mlockall $flags
		2389
		2390	Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
		2391	but is blocking.
		2392
		2393	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		2394
		2395	Calls the C<munlock> function, undoing the effects of a previous
		2396	C<aio_mlock> call (see its description for details).
		2397
		2398	=item IO::AIO::munlockall
		2399
		2400	Calls the C<munlockall> function.
		2401
		2402	On systems that do not implement C<munlockall>, this function returns
		2403	ENOSYS, otherwise the return value of C<munlockall>.
		2404
		2405	=item $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		2406
		2407	Uses the GNU/Linux C<accept4(2)> syscall, if available, to accept a socket
		2408	and return the new file handle on success, or sets C<$!> and returns
		2409	C<undef> on error.
		2410
		2411	The remote name of the new socket will be stored in C<$sockaddr>, which
		2412	will be extended to allow for at least C<$sockaddr_maxlen> octets. If the
		2413	socket name does not fit into C<$sockaddr_maxlen> octets, this is signaled
		2414	by returning a longer string in C<$sockaddr>, which might or might not be
		2415	truncated.
		2416
		2417	To accept name-less sockets, use C<undef> for C<$sockaddr> and C<0> for
		2418	C<$sockaddr_maxlen>.
		2419
		2420	The main reasons to use this syscall rather than portable C<accept(2)>
		2421	are that you can specify C<SOCK_NONBLOCK> and/or C<SOCK_CLOEXEC>
		2422	flags and you can accept name-less sockets by specifying C<0> for
		2423	C<$sockaddr_maxlen>, which is sadly not possible with perl's interface to
		2424	C<accept>.
		2425
		2426	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2427
		2428	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2429	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2430	should be the file offset.
		2431
		2432	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2433	silently corrupt the data in this case.
		2434
		2435	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2436	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2437	C<IO::AIO::SPLICE_F_GIFT>.
		2438
		2439	See the C<splice(2)> manpage for details.
		2440
		2441	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2442
		2443	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2444	description for C<IO::AIO::splice> above for details.
		2445
		2446	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2447
		2448	Attempts to query or change the pipe buffer size. Obviously works only
		2449	on pipes, and currently works only on GNU/Linux systems, and fails with
		2450	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2451	size on other systems, drop me a note.
		2452
		2453	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2454
		2455	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2456	C<$flags> is missing or C<0>, then this should be the same as a call to
		2457	perl's built-in C<pipe> function and create a new pipe, and works on
		2458	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2459	(..., 4096, O_BINARY)>.
		2460
		2461	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2462	the given flags (Linux 2.6.27, glibc 2.9).
		2463
		2464	On success, the read and write file handles are returned.
		2465
		2466	On error, nothing will be returned. If the pipe2 syscall is missing and
		2467	C<$flags> is non-zero, fails with C<ENOSYS>.
		2468
		2469	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2470	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2471	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2472
		2473	Example: create a pipe race-free w.r.t. threads and fork:
		2474
		2475	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2476	or die "pipe2: $!\n";
		2477
		2478	=item $fh = IO::AIO::memfd_create $pathname[, $flags]
		2479
		2480	This is a direct interface to the Linux L<memfd_create(2)> system
		2481	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2482	should be C<IO::AIO::MFD_CLOEXEC>.
		2483
		2484	On success, the new memfd filehandle is returned, otherwise returns
		2485	C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
		2486
		2487	Please refer to L<memfd_create(2)> for more info on this call.
		2488
		2489	The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
		2490	C<IO::AIO::MFD_ALLOW_SEALING> and C<IO::AIO::MFD_HUGETLB>.
		2491
		2492	Example: create a new memfd.
		2493
		2494	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2495	or die "memfd_create: $!\n";
		2496
		2497	=item $fh = IO::AIO::pidfd_open $pid[, $flags]
		2498
		2499	This is an interface to the Linux L<pidfd_open(2)> system call. The
		2500	default for C<$flags> is C<0>.
		2501
		2502	On success, a new pidfd filehandle is returned (that is already set to
		2503	close-on-exec), otherwise returns C<undef>. If the syscall is missing,
		2504	fails with C<ENOSYS>.
		2505
		2506	Example: open pid 6341 as pidfd.
		2507
		2508	my $fh = IO::AIO::pidfd_open 6341
		2509	or die "pidfd_open: $!\n";
		2510
		2511	=item $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		2512
		2513	This is an interface to the Linux L<pidfd_send_signal> system call. The
		2514	default for C<$siginfo> is C<undef> and the default for C<$flags> is C<0>.
		2515
		2516	Returns the system call status. If the syscall is missing, fails with
		2517	C<ENOSYS>.
		2518
		2519	When specified, C<$siginfo> must be a reference to a hash with one or more
		2520	of the following members:
		2521
		2522	=over
		2523
		2524	=item code - the C<si_code> member
		2525
		2526	=item pid - the C<si_pid> member
		2527
		2528	=item uid - the C<si_uid> member
		2529
		2530	=item value_int - the C<si_value.sival_int> member
		2531
		2532	=item value_ptr - the C<si_value.sival_ptr> member, specified as an integer
		2533
		2534	=back
		2535
		2536	Example: send a SIGKILL to the specified process.
		2537
		2538	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
		2539	and die "pidfd_send_signal: $!\n";
		2540
		2541	Example: send a SIGKILL to the specified process with extra data.
		2542
		2543	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
		2544	and die "pidfd_send_signal: $!\n";
		2545
		2546	=item $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		2547
		2548	This is an interface to the Linux L<pidfd_getfd> system call. The default
		2549	for C<$flags> is C<0>.
		2550
		2551	On success, returns a dup'ed copy of the target file descriptor (specified
		2552	as an integer) returned (that is already set to close-on-exec), otherwise
		2553	returns C<undef>. If the syscall is missing, fails with C<ENOSYS>.
		2554
		2555	Example: get a copy of standard error of another process and print soemthing to it.
		2556
		2557	my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
		2558	or die "pidfd_getfd: $!\n";
		2559	print $errfh "stderr\n";
		2560
		2561	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2562
		2563	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2564	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2565
		2566	On success, the new eventfd filehandle is returned, otherwise returns
		2567	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2568
		2569	Please refer to L<eventfd(2)> for more info on this call.
		2570
		2571	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2572	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2573
		2574	Example: create a new eventfd filehandle:
		2575
		2576	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2577	or die "eventfd: $!\n";
		2578
		2579	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2580
		2581	This is a direct interface to the Linux L<timerfd_create(2)> system
		2582	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2583	should be C<IO::AIO::TFD_CLOEXEC>.
		2584
		2585	On success, the new timerfd filehandle is returned, otherwise returns
		2586	C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
		2587
		2588	Please refer to L<timerfd_create(2)> for more info on this call.
		2589
		2590	The following C<$clockid> values are
		2591	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2592	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2593	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2594	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2595
		2596	The following C<$flags> values are available (Linux
		2597	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2598
		2599	Example: create a new timerfd and set it to one-second repeated alarms,
		2600	then wait for two alarms:
		2601
		2602	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2603	or die "timerfd_create: $!\n";
		2604
		2605	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2606	or die "timerfd_settime: $!\n";
		2607
		2608	for (1..2) {
		2609	8 == sysread $fh, my $buf, 8
		2610	or die "timerfd read failure\n";
		2611
		2612	printf "number of expirations (likely 1): %d\n",
		2613	unpack "Q", $buf;
		2614	}
		2615
		2616	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2617
		2618	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2619	call. Please refer to its manpage for more info on this call.
		2620
		2621	The new itimerspec is specified using two (possibly fractional) second
		2622	values, C<$new_interval> and C<$new_value>).
		2623
		2624	On success, the current interval and value are returned (as per
		2625	C<timerfd_gettime>). On failure, the empty list is returned.
		2626
		2627	The following C<$flags> values are
		2628	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2629	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2630
		2631	See C<IO::AIO::timerfd_create> for a full example.
		2632
		2633	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2634
		2635	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2636	call. Please refer to its manpage for more info on this call.
		2637
		2638	On success, returns the current values of interval and value for the given
		2639	timerfd (as potentially fractional second values). On failure, the empty
		2640	list is returned.
		2641
		2642	=back
		2643
1399	=cut	2644	=cut
1400		2645
1401	min_parallel 8;	2646	min_parallel 8;
1402		2647
1403	END { flush }	2648	END { flush }
1404		2649
1405	1;	2650	1;
1406		2651
		2652	=head1 EVENT LOOP INTEGRATION
		2653
		2654	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		2655	automatically into many event loops:
		2656
		2657	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		2658	use AnyEvent::AIO;
		2659
		2660	You can also integrate IO::AIO manually into many event loops, here are
		2661	some examples of how to do this:
		2662
		2663	# EV integration
		2664	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		2665
		2666	# Event integration
		2667	Event->io (fd => IO::AIO::poll_fileno,
		2668	poll => 'r',
		2669	cb => \&IO::AIO::poll_cb);
		2670
		2671	# Glib/Gtk2 integration
		2672	add_watch Glib::IO IO::AIO::poll_fileno,
		2673	in => sub { IO::AIO::poll_cb; 1 };
		2674
		2675	# Tk integration
		2676	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		2677	readable => \&IO::AIO::poll_cb);
		2678
		2679	# Danga::Socket integration
		2680	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		2681	\&IO::AIO::poll_cb);
		2682
1407	=head2 FORK BEHAVIOUR	2683	=head2 FORK BEHAVIOUR
1408		2684
1409	This module should do "the right thing" when the process using it forks:	2685	Usage of pthreads in a program changes the semantics of fork
		2686	considerably. Specifically, only async-safe functions can be called after
		2687	fork. Perl doesn't know about this, so in general, you cannot call fork
		2688	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2689	pthreads, so this applies, but many other extensions and (for inexplicable
		2690	reasons) perl itself often is linked against pthreads, so this limitation
		2691	applies to quite a lot of perls.
1410		2692
1411	Before the fork, IO::AIO enters a quiescent state where no requests	2693	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1412	can be added in other threads and no results will be processed. After	2694	only works in the process that loaded it. Forking is fully supported, but
1413	the fork the parent simply leaves the quiescent state and continues	2695	using IO::AIO in the child is not.
1414	request/result processing, while the child frees the request/result queue
1415	(so that the requests started before the fork will only be handled in the
1416	parent). Threads will be started on demand until the limit set in the
1417	parent process has been reached again.
1418		2696
1419	In short: the parent will, after a short pause, continue as if fork had	2697	You might get around by not I<using> IO::AIO before (or after)
1420	not been called, while the child will act as if IO::AIO has not been used	2698	forking. You could also try to call the L<IO::AIO::reinit> function in the
1421	yet.	2699	child:
		2700
		2701	=over 4
		2702
		2703	=item IO::AIO::reinit
		2704
		2705	Abandons all current requests and I/O threads and simply reinitialises all
		2706	data structures. This is not an operation supported by any standards, but
		2707	happens to work on GNU/Linux and some newer BSD systems.
		2708
		2709	The only reasonable use for this function is to call it after forking, if
		2710	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2711	the process will result in undefined behaviour. Calling it at any time
		2712	will also result in any undefined (by POSIX) behaviour.
		2713
		2714	=back
		2715
		2716	=head2 LINUX-SPECIFIC CALLS
		2717
		2718	When a call is documented as "linux-specific" then this means it
		2719	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2720	availability and compatibility of such calls regardless of the platform
		2721	it is compiled on, so platforms such as FreeBSD which often implement
		2722	these calls will work. When in doubt, call them and see if they fail wth
		2723	C<ENOSYS>.
1422		2724
1423	=head2 MEMORY USAGE	2725	=head2 MEMORY USAGE
1424		2726
1425	Per-request usage:	2727	Per-request usage:
1426		2728
…		…
1439	temporary buffers, and each thread requires a stack and other data	2741	temporary buffers, and each thread requires a stack and other data
1440	structures (usually around 16k-128k, depending on the OS).	2742	structures (usually around 16k-128k, depending on the OS).
1441		2743
1442	=head1 KNOWN BUGS	2744	=head1 KNOWN BUGS
1443		2745
1444	Known bugs will be fixed in the next release.	2746	Known bugs will be fixed in the next release :)
		2747
		2748	=head1 KNOWN ISSUES
		2749
		2750	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2751	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2752	non-created hash slots or other scalars I didn't think of. It's best to
		2753	avoid such and either use scalar variables or making sure that the scalar
		2754	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2755
		2756	I am not sure anything can be done about this, so this is considered a
		2757	known issue, rather than a bug.
1445		2758
1446	=head1 SEE ALSO	2759	=head1 SEE ALSO
1447		2760
1448	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2761	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1449	more natural syntax.	2762	more natural syntax and L<IO::FDPass> for file descriptor passing.
1450		2763
1451	=head1 AUTHOR	2764	=head1 AUTHOR
1452		2765
1453	Marc Lehmann <schmorp@schmorp.de>	2766	Marc Lehmann <schmorp@schmorp.de>
1454	http://home.schmorp.de/	2767	http://home.schmorp.de/

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