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Revision 1.176 by root, Sun Jan 10 23:05:11 2010 UTC vs.
Revision 1.318 by root, Sat Apr 1 02:14:05 2023 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
…		…
58	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
59	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
60	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
61	using threads anyway.	61	using threads anyway.
62		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
63	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,
64	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
65	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
66	call C<poll_cb> (or other C<aio_> functions) recursively.	70	call C<poll_cb> (or other C<aio_> functions) recursively.
67		71
68	=head2 EXAMPLE	72	=head2 EXAMPLE
69		73
70	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
71	F</etc/passwd> asynchronously:	75	F</etc/passwd> asynchronously:
72		76
73	use Fcntl;
74	use EV;	77	use EV;
75	use IO::AIO;	78	use IO::AIO;
76		79
77	# register the IO::AIO callback with EV	80	# register the IO::AIO callback with EV
78	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;
79		82
80	# queue the request to open /etc/passwd	83	# queue the request to open /etc/passwd
81	aio_open "/etc/passwd", O_RDONLY, 0, sub {	84	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
82	my $fh = shift	85	my $fh = shift
83	or die "error while opening: $!";	86	or die "error while opening: $!";
84		87
85	# stat'ing filehandles is generally non-blocking	88	# stat'ing filehandles is generally non-blocking
86	my $size = -s $fh;	89	my $size = -s $fh;
…		…
95		98
96	# file contents now in $contents	99	# file contents now in $contents
97	print $contents;	100	print $contents;
98		101
99	# exit event loop and program	102	# exit event loop and program
100	EV::unloop;	103	EV::break;
101	};	104	};
102	};	105	};
103		106
104	# possibly queue up other requests, or open GUI windows,	107	# possibly queue up other requests, or open GUI windows,
105	# check for sockets etc. etc.	108	# check for sockets etc. etc.
106		109
107	# process events as long as there are some:	110	# process events as long as there are some:
108	EV::loop;	111	EV::run;
109		112
110	=head1 REQUEST ANATOMY AND LIFETIME	113	=head1 REQUEST ANATOMY AND LIFETIME
111		114
112	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
113	directly visible to Perl.	116	directly visible to Perl.
…		…
168	use common::sense;	171	use common::sense;
169		172
170	use base 'Exporter';	173	use base 'Exporter';
171		174
172	BEGIN {	175	BEGIN {
173	our $VERSION = '3.5';	176	our $VERSION = 4.80;
174		177
175	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
176	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
177	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178	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
179	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
180	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
181	aio_chmod aio_utime aio_truncate	185	aio_chmod aio_utime aio_truncate
182	aio_msync aio_mtouch aio_statvfs);	186	aio_msync aio_mtouch aio_mlock aio_mlockall
		187	aio_statvfs
		188	aio_slurp
		189	aio_wd);
183		190
184	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	191	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
185	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	192	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
186	min_parallel max_parallel max_idle	193	min_parallel max_parallel max_idle idle_timeout
187	nreqs nready npending nthreads	194	nreqs nready npending nthreads
188	max_poll_time max_poll_reqs	195	max_poll_time max_poll_reqs
189	sendfile fadvise);	196	sendfile fadvise madvise
		197	mmap munmap mremap munlock munlockall
		198
		199	accept4 tee splice pipe2 pipesize
		200	fexecve mount umount memfd_create eventfd
		201	timerfd_create timerfd_settime timerfd_gettime
		202	pidfd_open pidfd_send_signal pidfd_getfd);
190		203
191	push @AIO_REQ, qw(aio_busy); # not exported	204	push @AIO_REQ, qw(aio_busy); # not exported
192		205
193	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	206	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
194		207
…		…
198		211
199	=head1 FUNCTIONS	212	=head1 FUNCTIONS
200		213
201	=head2 QUICK OVERVIEW	214	=head2 QUICK OVERVIEW
202		215
203	This section simply lists the prototypes of the most important functions	216	This section simply lists the prototypes most of the functions for
204	for quick reference. See the following sections for function-by-function	217	quick reference. See the following sections for function-by-function
205	documentation.	218	documentation.
206		219
		220	aio_wd $pathname, $callback->($wd)
207	aio_open $pathname, $flags, $mode, $callback->($fh)	221	aio_open $pathname, $flags, $mode, $callback->($fh)
208	aio_close $fh, $callback->($status)	222	aio_close $fh, $callback->($status)
		223	aio_seek $fh,$offset,$whence, $callback->($offs)
209	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	224	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
210	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	225	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
211	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	226	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
212	aio_readahead $fh,$offset,$length, $callback->($retval)	227	aio_readahead $fh,$offset,$length, $callback->($retval)
213	aio_stat $fh_or_path, $callback->($status)	228	aio_stat $fh_or_path, $callback->($status)
214	aio_lstat $fh, $callback->($status)	229	aio_lstat $fh, $callback->($status)
215	aio_statvfs $fh_or_path, $callback->($statvfs)	230	aio_statvfs $fh_or_path, $callback->($statvfs)
216	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	231	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
217	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	232	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		233	aio_chmod $fh_or_path, $mode, $callback->($status)
218	aio_truncate $fh_or_path, $offset, $callback->($status)	234	aio_truncate $fh_or_path, $offset, $callback->($status)
219	aio_chmod $fh_or_path, $mode, $callback->($status)	235	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		236	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
220	aio_unlink $pathname, $callback->($status)	237	aio_unlink $pathname, $callback->($status)
221	aio_mknod $path, $mode, $dev, $callback->($status)	238	aio_mknod $pathname, $mode, $dev, $callback->($status)
222	aio_link $srcpath, $dstpath, $callback->($status)	239	aio_link $srcpath, $dstpath, $callback->($status)
223	aio_symlink $srcpath, $dstpath, $callback->($status)	240	aio_symlink $srcpath, $dstpath, $callback->($status)
224	aio_readlink $path, $callback->($link)	241	aio_readlink $pathname, $callback->($link)
		242	aio_realpath $pathname, $callback->($path)
225	aio_rename $srcpath, $dstpath, $callback->($status)	243	aio_rename $srcpath, $dstpath, $callback->($status)
		244	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
226	aio_mkdir $pathname, $mode, $callback->($status)	245	aio_mkdir $pathname, $mode, $callback->($status)
227	aio_rmdir $pathname, $callback->($status)	246	aio_rmdir $pathname, $callback->($status)
228	aio_readdir $pathname, $callback->($entries)	247	aio_readdir $pathname, $callback->($entries)
229	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	248	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
230	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	249	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
231	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	250	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		251	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
232	aio_load $path, $data, $callback->($status)	252	aio_load $pathname, $data, $callback->($status)
233	aio_copy $srcpath, $dstpath, $callback->($status)	253	aio_copy $srcpath, $dstpath, $callback->($status)
234	aio_move $srcpath, $dstpath, $callback->($status)	254	aio_move $srcpath, $dstpath, $callback->($status)
235	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
236	aio_rmtree $path, $callback->($status)	255	aio_rmtree $pathname, $callback->($status)
		256	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		257	aio_ioctl $fh, $request, $buf, $callback->($status)
237	aio_sync $callback->($status)	258	aio_sync $callback->($status)
		259	aio_syncfs $fh, $callback->($status)
238	aio_fsync $fh, $callback->($status)	260	aio_fsync $fh, $callback->($status)
239	aio_fdatasync $fh, $callback->($status)	261	aio_fdatasync $fh, $callback->($status)
240	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	262	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
241	aio_pathsync $path, $callback->($status)	263	aio_pathsync $pathname, $callback->($status)
242	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	264	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
243	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	265	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		266	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		267	aio_mlockall $flags, $callback->($status)
244	aio_group $callback->(...)	268	aio_group $callback->(...)
245	aio_nop $callback->()	269	aio_nop $callback->()
246		270
247	$prev_pri = aioreq_pri [$pri]	271	$prev_pri = aioreq_pri [$pri]
248	aioreq_nice $pri_adjust	272	aioreq_nice $pri_adjust
…		…
254	IO::AIO::max_poll_reqs $nreqs	278	IO::AIO::max_poll_reqs $nreqs
255	IO::AIO::max_poll_time $seconds	279	IO::AIO::max_poll_time $seconds
256	IO::AIO::min_parallel $nthreads	280	IO::AIO::min_parallel $nthreads
257	IO::AIO::max_parallel $nthreads	281	IO::AIO::max_parallel $nthreads
258	IO::AIO::max_idle $nthreads	282	IO::AIO::max_idle $nthreads
		283	IO::AIO::idle_timeout $seconds
259	IO::AIO::max_outstanding $maxreqs	284	IO::AIO::max_outstanding $maxreqs
260	IO::AIO::nreqs	285	IO::AIO::nreqs
261	IO::AIO::nready	286	IO::AIO::nready
262	IO::AIO::npending	287	IO::AIO::npending
		288	IO::AIO::reinit
		289
		290	$nfd = IO::AIO::get_fdlimit
		291	IO::AIO::min_fdlimit $nfd
263		292
264	IO::AIO::sendfile $ofh, $ifh, $offset, $count	293	IO::AIO::sendfile $ofh, $ifh, $offset, $count
265	IO::AIO::fadvise $fh, $offset, $len, $advice	294	IO::AIO::fadvise $fh, $offset, $len, $advice
266	IO::AIO::mlockall $flags	295	IO::AIO::fexecve $fh, $argv, $envp
		296
		297	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		298	IO::AIO::munmap $scalar
		299	IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
		300	IO::AIO::madvise $scalar, $offset, $length, $advice
		301	IO::AIO::mprotect $scalar, $offset, $length, $protect
		302	IO::AIO::munlock $scalar, $offset = 0, $length = undef
267	IO::AIO::munlockall	303	IO::AIO::munlockall
268		304
269	=head2 AIO REQUEST FUNCTIONS	305	# stat extensions
		306	$counter = IO::AIO::st_gen
		307	$seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		308	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		309	$nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		310	$seconds = IO::AIO::st_btimesec
		311	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		312
		313	# very much unportable syscalls
		314	IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
		315	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		316	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		317
		318	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		319	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		320
		321	$fh = IO::AIO::eventfd [$initval, [$flags]]
		322	$fh = IO::AIO::memfd_create $pathname[, $flags]
		323
		324	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		325	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		326	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		327
		328	$fh = IO::AIO::pidfd_open $pid[, $flags]
		329	$status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		330	$fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		331
		332	$retval = IO::AIO::mount $special, $path, $fstype, $flags = 0, $data = undef
		333	$retval = IO::AIO::umount $path, $flags = 0
		334
		335	=head2 API NOTES
270		336
271	All the C<aio_*> calls are more or less thin wrappers around the syscall	337	All the C<aio_*> calls are more or less thin wrappers around the syscall
272	with the same name (sans C<aio_>). The arguments are similar or identical,	338	with the same name (sans C<aio_>). The arguments are similar or identical,
273	and they all accept an additional (and optional) C<$callback> argument	339	and they all accept an additional (and optional) C<$callback> argument
274	which must be a code reference. This code reference will get called with	340	which must be a code reference. This code reference will be called after
275	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	341	the syscall has been executed in an asynchronous fashion. The results
276	perl, which usually delivers "false") as its sole argument after the given	342	of the request will be passed as arguments to the callback (and, if an
277	syscall has been executed asynchronously.	343	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		344	most syscalls return C<-1> on error, unlike perl, which usually delivers
		345	"false").
		346
		347	Some requests (such as C<aio_readdir>) pass the actual results and
		348	communicate failures by passing C<undef>.
278		349
279	All functions expecting a filehandle keep a copy of the filehandle	350	All functions expecting a filehandle keep a copy of the filehandle
280	internally until the request has finished.	351	internally until the request has finished.
281		352
282	All functions return request objects of type L<IO::AIO::REQ> that allow	353	All functions return request objects of type L<IO::AIO::REQ> that allow
283	further manipulation of those requests while they are in-flight.	354	further manipulation of those requests while they are in-flight.
284		355
285	The pathnames you pass to these routines I<must> be absolute and	356	The pathnames you pass to these routines I<should> be absolute. The
286	encoded as octets. The reason for the former is that at the time the	357	reason for this is that at the time the request is being executed, the
287	request is being executed, the current working directory could have	358	current working directory could have changed. Alternatively, you can
288	changed. Alternatively, you can make sure that you never change the	359	make sure that you never change the current working directory anywhere
289	current working directory anywhere in the program and then use relative	360	in the program and then use relative paths. You can also take advantage
290	paths.	361	of IO::AIOs working directory abstraction, that lets you specify paths
		362	relative to some previously-opened "working directory object" - see the
		363	description of the C<IO::AIO::WD> class later in this document.
291		364
292	To encode pathnames as octets, either make sure you either: a) always pass	365	To encode pathnames as octets, either make sure you either: a) always pass
293	in filenames you got from outside (command line, readdir etc.) without	366	in filenames you got from outside (command line, readdir etc.) without
294	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	367	tinkering, b) are in your native filesystem encoding, c) use the Encode
295	your pathnames to the locale (or other) encoding in effect in the user	368	module and encode your pathnames to the locale (or other) encoding in
296	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	369	effect in the user environment, d) use Glib::filename_from_unicode on
297	use something else to ensure your scalar has the correct contents.	370	unicode filenames or e) use something else to ensure your scalar has the
		371	correct contents.
298		372
299	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	373	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
300	handles correctly whether it is set or not.	374	handles correctly whether it is set or not.
		375
		376	=head2 AIO REQUEST FUNCTIONS
301		377
302	=over 4	378	=over 4
303		379
304	=item $prev_pri = aioreq_pri [$pri]	380	=item $prev_pri = aioreq_pri [$pri]
305		381
…		…
335		411
336		412
337	=item aio_open $pathname, $flags, $mode, $callback->($fh)	413	=item aio_open $pathname, $flags, $mode, $callback->($fh)
338		414
339	Asynchronously open or create a file and call the callback with a newly	415	Asynchronously open or create a file and call the callback with a newly
340	created filehandle for the file.	416	created filehandle for the file (or C<undef> in case of an error).
341
342	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
343	for an explanation.
344		417
345	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	418	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
346	list. They are the same as used by C<sysopen>.	419	list. They are the same as used by C<sysopen>.
347		420
348	Likewise, C<$mode> specifies the mode of the newly created file, if it	421	Likewise, C<$mode> specifies the mode of the newly created file, if it
…		…
352	by the umask in effect then the request is being executed, so better never	425	by the umask in effect then the request is being executed, so better never
353	change the umask.	426	change the umask.
354		427
355	Example:	428	Example:
356		429
357	aio_open "/etc/passwd", O_RDONLY, 0, sub {	430	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
358	if ($_[0]) {	431	if ($_[0]) {
359	print "open successful, fh is $_[0]\n";	432	print "open successful, fh is $_[0]\n";
360	...	433	...
361	} else {	434	} else {
362	die "open failed: $!\n";	435	die "open failed: $!\n";
363	}	436	}
364	};	437	};
365		438
		439	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		440	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		441	following POSIX and non-POSIX constants are available (missing ones on
		442	your system are, as usual, C<0>):
		443
		444	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		445	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		446	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
		447
366		448
367	=item aio_close $fh, $callback->($status)	449	=item aio_close $fh, $callback->($status)
368		450
369	Asynchronously close a file and call the callback with the result	451	Asynchronously close a file and call the callback with the result
370	code.	452	code.
…		…
379	Or in other words: the file descriptor will be closed, but it will not be	461	Or in other words: the file descriptor will be closed, but it will not be
380	free for reuse until the perl filehandle is closed.	462	free for reuse until the perl filehandle is closed.
381		463
382	=cut	464	=cut
383		465
		466	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		467
		468	Seeks the filehandle to the new C<$offset>, similarly to perl's
		469	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		470	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		471	C<IO::AIO::SEEK_END>).
		472
		473	The resulting absolute offset will be passed to the callback, or C<-1> in
		474	case of an error.
		475
		476	In theory, the C<$whence> constants could be different than the
		477	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		478	so don't panic.
		479
		480	As a GNU/Linux (and maybe Solaris) extension, also the constants
		481	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		482	could be found. No guarantees about suitability for use in C<aio_seek> or
		483	Perl's C<sysseek> can be made though, although I would naively assume they
		484	"just work".
		485
384	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	486	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
385		487
386	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	488	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
387		489
388	Reads or writes C<$length> bytes from or to the specified C<$fh> and	490	Reads or writes C<$length> bytes from or to the specified C<$fh> and
389	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	491	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
390	and calls the callback without the actual number of bytes read (or -1 on	492	calls the callback with the actual number of bytes transferred (or -1 on
391	error, just like the syscall).	493	error, just like the syscall).
392		494
393	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	495	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
394	offset plus the actual number of bytes read.	496	offset plus the actual number of bytes read.
395		497
…		…
420		522
421	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	523	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
422	reading at byte offset C<$in_offset>, and starts writing at the current	524	reading at byte offset C<$in_offset>, and starts writing at the current
423	file offset of C<$out_fh>. Because of that, it is not safe to issue more	525	file offset of C<$out_fh>. Because of that, it is not safe to issue more
424	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	526	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
425	other.	527	other. The same C<$in_fh> works fine though, as this function does not
		528	move or use the file offset of C<$in_fh>.
426		529
		530	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		531	are written, and there is no way to find out how many more bytes have been
		532	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		533	number of bytes written to C<$out_fh>. Only if the result value equals
		534	C<$length> one can assume that C<$length> bytes have been read.
		535
		536	Unlike with other C<aio_> functions, it makes a lot of sense to use
		537	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		538	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		539	the socket I/O will be non-blocking. Note, however, that you can run
		540	into a trap where C<aio_sendfile> reads some data with readahead, then
		541	fails to write all data, and when the socket is ready the next time, the
		542	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		543	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		544	resource usage.
		545
427	This call tries to make use of a native C<sendfile> syscall to provide	546	This call tries to make use of a native C<sendfile>-like syscall to
428	zero-copy operation. For this to work, C<$out_fh> should refer to a	547	provide zero-copy operation. For this to work, C<$out_fh> should refer to
429	socket, and C<$in_fh> should refer to an mmap'able file.	548	a socket, and C<$in_fh> should refer to an mmap'able file.
430		549
431	If a native sendfile cannot be found or it fails with C<ENOSYS>,	550	If a native sendfile cannot be found or it fails with C<ENOSYS>,
432	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,	551	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
433	it will be emulated, so you can call C<aio_sendfile> on any type of	552	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
434	filehandle regardless of the limitations of the operating system.	553	type of filehandle regardless of the limitations of the operating system.
435		554
436	Please note, however, that C<aio_sendfile> can read more bytes from	555	As native sendfile syscalls (as practically any non-POSIX interface hacked
437	C<$in_fh> than are written, and there is no way to find out how many	556	together in a hurry to improve benchmark numbers) tend to be rather buggy
438	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	557	on many systems, this implementation tries to work around some known bugs
439	provides the number of bytes written to C<$out_fh>. Only if the result	558	in Linux and FreeBSD kernels (probably others, too), but that might fail,
440	value equals C<$length> one can assume that C<$length> bytes have been	559	so you really really should check the return value of C<aio_sendfile> -
441	read.	560	fewer bytes than expected might have been transferred.
442		561
443		562
444	=item aio_readahead $fh,$offset,$length, $callback->($retval)	563	=item aio_readahead $fh,$offset,$length, $callback->($retval)
445		564
446	C<aio_readahead> populates the page cache with data from a file so that	565	C<aio_readahead> populates the page cache with data from a file so that
…		…
450	whole pages, so that offset is effectively rounded down to a page boundary	569	whole pages, so that offset is effectively rounded down to a page boundary
451	and bytes are read up to the next page boundary greater than or equal to	570	and bytes are read up to the next page boundary greater than or equal to
452	(off-set+length). C<aio_readahead> does not read beyond the end of the	571	(off-set+length). C<aio_readahead> does not read beyond the end of the
453	file. The current file offset of the file is left unchanged.	572	file. The current file offset of the file is left unchanged.
454		573
455	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	574	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
456	emulated by simply reading the data, which would have a similar effect.	575	be emulated by simply reading the data, which would have a similar effect.
457		576
458		577
459	=item aio_stat $fh_or_path, $callback->($status)	578	=item aio_stat $fh_or_path, $callback->($status)
460		579
461	=item aio_lstat $fh, $callback->($status)	580	=item aio_lstat $fh, $callback->($status)
462		581
463	Works like perl's C<stat> or C<lstat> in void context. The callback will	582	Works almost exactly like perl's C<stat> or C<lstat> in void context. The
464	be called after the stat and the results will be available using C<stat _>	583	callback will be called after the stat and the results will be available
465	or C<-s _> etc...	584	using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
466		585	and C<-T>).
467	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
468	for an explanation.
469		586
470	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	587	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
471	error when stat'ing a large file, the results will be silently truncated	588	error when stat'ing a large file, the results will be silently truncated
472	unless perl itself is compiled with large file support.	589	unless perl itself is compiled with large file support.
		590
		591	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		592	following constants and functions (if not implemented, the constants will
		593	be C<0> and the functions will either C<croak> or fall back on traditional
		594	behaviour).
		595
		596	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		597	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		598	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		599
		600	To access higher resolution stat timestamps, see L<SUBSECOND STAT TIME
		601	ACCESS>.
473		602
474	Example: Print the length of F</etc/passwd>:	603	Example: Print the length of F</etc/passwd>:
475		604
476	aio_stat "/etc/passwd", sub {	605	aio_stat "/etc/passwd", sub {
477	$_[0] and die "stat failed: $!";	606	$_[0] and die "stat failed: $!";
…		…
521	namemax => 255,	650	namemax => 255,
522	frsize => 1024,	651	frsize => 1024,
523	fsid => 1810	652	fsid => 1810
524	}	653	}
525		654
526
527	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	655	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
528		656
529	Works like perl's C<utime> function (including the special case of $atime	657	Works like perl's C<utime> function (including the special case of $atime
530	and $mtime being undef). Fractional times are supported if the underlying	658	and $mtime being undef). Fractional times are supported if the underlying
531	syscalls support them.	659	syscalls support them.
532		660
533	When called with a pathname, uses utimes(2) if available, otherwise	661	When called with a pathname, uses utimensat(2) or utimes(2) if available,
534	utime(2). If called on a file descriptor, uses futimes(2) if available,	662	otherwise utime(2). If called on a file descriptor, uses futimens(2)
535	otherwise returns ENOSYS, so this is not portable.	663	or futimes(2) if available, otherwise returns ENOSYS, so this is not
		664	portable.
536		665
537	Examples:	666	Examples:
538		667
539	# set atime and mtime to current time (basically touch(1)):	668	# set atime and mtime to current time (basically touch(1)):
540	aio_utime "path", undef, undef;	669	aio_utime "path", undef, undef;
…		…
558	=item aio_truncate $fh_or_path, $offset, $callback->($status)	687	=item aio_truncate $fh_or_path, $offset, $callback->($status)
559		688
560	Works like truncate(2) or ftruncate(2).	689	Works like truncate(2) or ftruncate(2).
561		690
562		691
		692	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		693
		694	Allocates or frees disk space according to the C<$mode> argument. See the
		695	linux C<fallocate> documentation for details.
		696
		697	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		698	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		699	to deallocate a file range.
		700
		701	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		702	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		703	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		704	to unshare shared blocks (see your L<fallocate(2)> manpage).
		705
		706	The file system block size used by C<fallocate> is presumably the
		707	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		708	can dictate other limitations.
		709
		710	If C<fallocate> isn't available or cannot be emulated (currently no
		711	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		712
		713
563	=item aio_chmod $fh_or_path, $mode, $callback->($status)	714	=item aio_chmod $fh_or_path, $mode, $callback->($status)
564		715
565	Works like perl's C<chmod> function.	716	Works like perl's C<chmod> function.
566		717
567		718
…		…
569		720
570	Asynchronously unlink (delete) a file and call the callback with the	721	Asynchronously unlink (delete) a file and call the callback with the
571	result code.	722	result code.
572		723
573		724
574	=item aio_mknod $path, $mode, $dev, $callback->($status)	725	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
575		726
576	[EXPERIMENTAL]	727	[EXPERIMENTAL]
577		728
578	Asynchronously create a device node (or fifo). See mknod(2).	729	Asynchronously create a device node (or fifo). See mknod(2).
579		730
580	The only (POSIX-) portable way of calling this function is:	731	The only (POSIX-) portable way of calling this function is:
581		732
582	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	733	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
583		734
		735	See C<aio_stat> for info about some potentially helpful extra constants
		736	and functions.
584		737
585	=item aio_link $srcpath, $dstpath, $callback->($status)	738	=item aio_link $srcpath, $dstpath, $callback->($status)
586		739
587	Asynchronously create a new link to the existing object at C<$srcpath> at	740	Asynchronously create a new link to the existing object at C<$srcpath> at
588	the path C<$dstpath> and call the callback with the result code.	741	the path C<$dstpath> and call the callback with the result code.
…		…
592		745
593	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	746	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
594	the path C<$dstpath> and call the callback with the result code.	747	the path C<$dstpath> and call the callback with the result code.
595		748
596		749
597	=item aio_readlink $path, $callback->($link)	750	=item aio_readlink $pathname, $callback->($link)
598		751
599	Asynchronously read the symlink specified by C<$path> and pass it to	752	Asynchronously read the symlink specified by C<$path> and pass it to
600	the callback. If an error occurs, nothing or undef gets passed to the	753	the callback. If an error occurs, nothing or undef gets passed to the
601	callback.	754	callback.
602		755
603		756
		757	=item aio_realpath $pathname, $callback->($path)
		758
		759	Asynchronously make the path absolute and resolve any symlinks in
		760	C<$path>. The resulting path only consists of directories (same as
		761	L<Cwd::realpath>).
		762
		763	This request can be used to get the absolute path of the current working
		764	directory by passing it a path of F<.> (a single dot).
		765
		766
604	=item aio_rename $srcpath, $dstpath, $callback->($status)	767	=item aio_rename $srcpath, $dstpath, $callback->($status)
605		768
606	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	769	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
607	rename(2) and call the callback with the result code.	770	rename(2) and call the callback with the result code.
		771
		772	On systems that support the AIO::WD working directory abstraction
		773	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		774	of failing, C<rename> is called on the absolute path of C<$wd>.
		775
		776
		777	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		778
		779	Basically a version of C<aio_rename> with an additional C<$flags>
		780	argument. Calling this with C<$flags=0> is the same as calling
		781	C<aio_rename>.
		782
		783	Non-zero flags are currently only supported on GNU/Linux systems that
		784	support renameat2. Other systems fail with C<ENOSYS> in this case.
		785
		786	The following constants are available (missing ones are, as usual C<0>),
		787	see renameat2(2) for details:
		788
		789	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		790	and C<IO::AIO::RENAME_WHITEOUT>.
608		791
609		792
610	=item aio_mkdir $pathname, $mode, $callback->($status)	793	=item aio_mkdir $pathname, $mode, $callback->($status)
611		794
612	Asynchronously mkdir (create) a directory and call the callback with	795	Asynchronously mkdir (create) a directory and call the callback with
…		…
617	=item aio_rmdir $pathname, $callback->($status)	800	=item aio_rmdir $pathname, $callback->($status)
618		801
619	Asynchronously rmdir (delete) a directory and call the callback with the	802	Asynchronously rmdir (delete) a directory and call the callback with the
620	result code.	803	result code.
621		804
		805	On systems that support the AIO::WD working directory abstraction
		806	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		807	C<rmdir> is called on the absolute path of C<$wd>.
		808
622		809
623	=item aio_readdir $pathname, $callback->($entries)	810	=item aio_readdir $pathname, $callback->($entries)
624		811
625	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	812	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
626	directory (i.e. opendir + readdir + closedir). The entries will not be	813	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
630	array-ref with the filenames.	817	array-ref with the filenames.
631		818
632		819
633	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	820	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
634		821
635	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	822	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
636	behaviour and output format. In case of an error, C<$entries> will be	823	tune behaviour and output format. In case of an error, C<$entries> will be
637	C<undef>.	824	C<undef>.
638		825
639	The flags are a combination of the following constants, ORed together (the	826	The flags are a combination of the following constants, ORed together (the
640	flags will also be passed to the callback, possibly modified):	827	flags will also be passed to the callback, possibly modified):
641		828
642	=over 4	829	=over 4
643		830
644	=item IO::AIO::READDIR_DENTS	831	=item IO::AIO::READDIR_DENTS
645		832
646	When this flag is off, then the callback gets an arrayref with of names	833	Normally the callback gets an arrayref consisting of names only (as
647	only (as with C<aio_readdir>), otherwise it gets an arrayref with	834	with C<aio_readdir>). If this flag is set, then the callback gets an
648	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	835	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
649	entry in more detail.	836	single directory entry in more detail:
650		837
651	C<$name> is the name of the entry.	838	C<$name> is the name of the entry.
652		839
653	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	840	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
654		841
655	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	842	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
656	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	843	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
657	C<IO::AIO::DT_WHT>.	844	C<IO::AIO::DT_WHT>.
658		845
659	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	846	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
660	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	847	to know, you have to run stat yourself. Also, for speed/memory reasons,
661	scalars are read-only: you can not modify them.	848	the C<$type> scalars are read-only: you must not modify them.
662		849
663	C<$inode> is the inode number (which might not be exact on systems with 64	850	C<$inode> is the inode number (which might not be exact on systems with 64
664	bit inode numbers and 32 bit perls). This field has unspecified content on	851	bit inode numbers and 32 bit perls). This field has unspecified content on
665	systems that do not deliver the inode information.	852	systems that do not deliver the inode information.
666		853
667	=item IO::AIO::READDIR_DIRS_FIRST	854	=item IO::AIO::READDIR_DIRS_FIRST
668		855
669	When this flag is set, then the names will be returned in an order where	856	When this flag is set, then the names will be returned in an order where
670	likely directories come first. This is useful when you need to quickly	857	likely directories come first, in optimal stat order. This is useful when
671	find directories, or you want to find all directories while avoiding to	858	you need to quickly find directories, or you want to find all directories
672	stat() each entry.	859	while avoiding to stat() each entry.
673		860
674	If the system returns type information in readdir, then this is used	861	If the system returns type information in readdir, then this is used
675	to find directories directly. Otherwise, likely directories are files	862	to find directories directly. Otherwise, likely directories are names
676	beginning with ".", or otherwise files with no dots, of which files with	863	beginning with ".", or otherwise names with no dots, of which names with
677	short names are tried first.	864	short names are tried first.
678		865
679	=item IO::AIO::READDIR_STAT_ORDER	866	=item IO::AIO::READDIR_STAT_ORDER
680		867
681	When this flag is set, then the names will be returned in an order	868	When this flag is set, then the names will be returned in an order
682	suitable for stat()'ing each one. That is, when you plan to stat()	869	suitable for stat()'ing each one. That is, when you plan to stat() most or
683	all files in the given directory, then the returned order will likely	870	all files in the given directory, then the returned order will likely be
684	be fastest.	871	faster.
685		872
686	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then	873	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
687	the likely dirs come first, resulting in a less optimal stat order.	874	then the likely dirs come first, resulting in a less optimal stat order
		875	for stat'ing all entries, but likely a more optimal order for finding
		876	subdirectories.
688		877
689	=item IO::AIO::READDIR_FOUND_UNKNOWN	878	=item IO::AIO::READDIR_FOUND_UNKNOWN
690		879
691	This flag should not be set when calling C<aio_readdirx>. Instead, it	880	This flag should not be set when calling C<aio_readdirx>. Instead, it
692	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	881	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
693	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	882	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
694	C<$type>'s are known, which can be used to speed up some algorithms.	883	C<$type>'s are known, which can be used to speed up some algorithms.
695		884
696	=back	885	=back
697		886
698		887
		888	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		889
		890	Opens, reads and closes the given file. The data is put into C<$data>,
		891	which is resized as required.
		892
		893	If C<$offset> is negative, then it is counted from the end of the file.
		894
		895	If C<$length> is zero, then the remaining length of the file is
		896	used. Also, in this case, the same limitations to modifying C<$data> apply
		897	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		898	with C<substr>. If the size of the file is known, specifying a non-zero
		899	C<$length> results in a performance advantage.
		900
		901	This request is similar to the older C<aio_load> request, but since it is
		902	a single request, it might be more efficient to use.
		903
		904	Example: load F</etc/passwd> into C<$passwd>.
		905
		906	my $passwd;
		907	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		908	$_[0] >= 0
		909	or die "/etc/passwd: $!\n";
		910
		911	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		912	print $passwd;
		913	};
		914	IO::AIO::flush;
		915
		916
699	=item aio_load $path, $data, $callback->($status)	917	=item aio_load $pathname, $data, $callback->($status)
700		918
701	This is a composite request that tries to fully load the given file into	919	This is a composite request that tries to fully load the given file into
702	memory. Status is the same as with aio_read.	920	memory. Status is the same as with aio_read.
		921
		922	Using C<aio_slurp> might be more efficient, as it is a single request.
703		923
704	=cut	924	=cut
705		925
706	sub aio_load($$;$) {	926	sub aio_load($$;$) {
707	my ($path, undef, $cb) = @_;	927	my ($path, undef, $cb) = @_;
…		…
727	=item aio_copy $srcpath, $dstpath, $callback->($status)	947	=item aio_copy $srcpath, $dstpath, $callback->($status)
728		948
729	Try to copy the I<file> (directories not supported as either source or	949	Try to copy the I<file> (directories not supported as either source or
730	destination) from C<$srcpath> to C<$dstpath> and call the callback with	950	destination) from C<$srcpath> to C<$dstpath> and call the callback with
731	a status of C<0> (ok) or C<-1> (error, see C<$!>).	951	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		952
		953	Existing destination files will be truncated.
732		954
733	This is a composite request that creates the destination file with	955	This is a composite request that creates the destination file with
734	mode 0200 and copies the contents of the source file into it using	956	mode 0200 and copies the contents of the source file into it using
735	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	957	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
736	uid/gid, in that order.	958	uid/gid, in that order.
…		…
826	if ($_[0] && $! == EXDEV) {	1048	if ($_[0] && $! == EXDEV) {
827	aioreq_pri $pri;	1049	aioreq_pri $pri;
828	add $grp aio_copy $src, $dst, sub {	1050	add $grp aio_copy $src, $dst, sub {
829	$grp->result ($_[0]);	1051	$grp->result ($_[0]);
830		1052
831	if (!$_[0]) {	1053	unless ($_[0]) {
832	aioreq_pri $pri;	1054	aioreq_pri $pri;
833	add $grp aio_unlink $src;	1055	add $grp aio_unlink $src;
834	}	1056	}
835	};	1057	};
836	} else {	1058	} else {
…		…
839	};	1061	};
840		1062
841	$grp	1063	$grp
842	}	1064	}
843		1065
844	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1066	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
845		1067
846	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1068	Scans a directory (similar to C<aio_readdir>) but additionally tries to
847	efficiently separate the entries of directory C<$path> into two sets of	1069	efficiently separate the entries of directory C<$path> into two sets of
848	names, directories you can recurse into (directories), and ones you cannot	1070	names, directories you can recurse into (directories), and ones you cannot
849	recurse into (everything else, including symlinks to directories).	1071	recurse into (everything else, including symlinks to directories).
850		1072
851	C<aio_scandir> is a composite request that creates of many sub requests_	1073	C<aio_scandir> is a composite request that generates many sub requests.
852	C<$maxreq> specifies the maximum number of outstanding aio requests that	1074	C<$maxreq> specifies the maximum number of outstanding aio requests that
853	this function generates. If it is C<< <= 0 >>, then a suitable default	1075	this function generates. If it is C<< <= 0 >>, then a suitable default
854	will be chosen (currently 4).	1076	will be chosen (currently 4).
855		1077
856	On error, the callback is called without arguments, otherwise it receives	1078	On error, the callback is called without arguments, otherwise it receives
…		…
880	Then entries will be sorted into likely directories a non-initial dot	1102	Then entries will be sorted into likely directories a non-initial dot
881	currently) and likely non-directories (see C<aio_readdirx>). Then every	1103	currently) and likely non-directories (see C<aio_readdirx>). Then every
882	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1104	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
883	in order of their inode numbers. If that succeeds, it assumes that the	1105	in order of their inode numbers. If that succeeds, it assumes that the
884	entry is a directory or a symlink to directory (which will be checked	1106	entry is a directory or a symlink to directory (which will be checked
885	seperately). This is often faster than stat'ing the entry itself because	1107	separately). This is often faster than stat'ing the entry itself because
886	filesystems might detect the type of the entry without reading the inode	1108	filesystems might detect the type of the entry without reading the inode
887	data (e.g. ext2fs filetype feature), even on systems that cannot return	1109	data (e.g. ext2fs filetype feature), even on systems that cannot return
888	the filetype information on readdir.	1110	the filetype information on readdir.
889		1111
890	If the known number of directories (link count - 2) has been reached, the	1112	If the known number of directories (link count - 2) has been reached, the
…		…
906		1128
907	my $grp = aio_group $cb;	1129	my $grp = aio_group $cb;
908		1130
909	$maxreq = 4 if $maxreq <= 0;	1131	$maxreq = 4 if $maxreq <= 0;
910		1132
911	# stat once	1133	# get a wd object
912	aioreq_pri $pri;	1134	aioreq_pri $pri;
913	add $grp aio_stat $path, sub {	1135	add $grp aio_wd $path, sub {
		1136	$_[0]
914	return $grp->result () if $_[0];	1137	or return $grp->result ();
915	my $now = time;
916	my $hash1 = join ":", (stat _)[0,1,3,7,9];
917		1138
918	# read the directory entries	1139	my $wd = [shift, "."];
		1140
		1141	# stat once
919	aioreq_pri $pri;	1142	aioreq_pri $pri;
920	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1143	add $grp aio_stat $wd, sub {
921	my $entries = shift
922	or return $grp->result ();	1144	return $grp->result () if $_[0];
		1145	my $now = time;
		1146	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		1147	my $rdxflags = READDIR_DIRS_FIRST;
923		1148
924	# stat the dir another time	1149	if ((stat _)[3] < 2) {
		1150	# at least one non-POSIX filesystem exists
		1151	# that returns useful DT_type values: btrfs,
		1152	# so optimise for this here by requesting dents
		1153	$rdxflags |= READDIR_DENTS;
		1154	}
		1155
		1156	# read the directory entries
925	aioreq_pri $pri;	1157	aioreq_pri $pri;
926	add $grp aio_stat $path, sub {	1158	add $grp aio_readdirx $wd, $rdxflags, sub {
927	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1159	my ($entries, $flags) = @_
		1160	or return $grp->result ();
928		1161
		1162	if ($rdxflags & READDIR_DENTS) {
		1163	# if we requested type values, see if we can use them directly.
		1164
		1165	# if there were any DT_UNKNOWN entries then we assume we
		1166	# don't know. alternatively, we could assume that if we get
		1167	# one DT_DIR, then all directories are indeed marked with
		1168	# DT_DIR, but this seems not required for btrfs, and this
		1169	# is basically the "btrfs can't get it's act together" code
		1170	# branch.
		1171	unless ($flags & READDIR_FOUND_UNKNOWN) {
		1172	# now we have valid DT_ information for all entries,
		1173	# so use it as an optimisation without further stat's.
		1174	# they must also all be at the beginning of @$entries
		1175	# by now.
		1176
929	my $ndirs;	1177	my $dirs;
930		1178
931	# take the slow route if anything looks fishy
932	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
933	$ndirs = -1;
934	} else {
935	# if nlink == 2, we are finished
936	# for non-posix-fs's, we rely on nlink < 2
937	$ndirs = (stat _)[3] - 2
938	or return $grp->result ([], $entries);
939	}
940
941	my (@dirs, @nondirs);
942
943	my $statgrp = add $grp aio_group sub {
944	$grp->result (\@dirs, \@nondirs);
945	};
946
947	limit $statgrp $maxreq;
948	feed $statgrp sub {
949	return unless @$entries;
950	my $entry = shift @$entries;
951
952	aioreq_pri $pri;
953	add $statgrp aio_stat "$path/$entry/.", sub {
954	if ($_[0] < 0) {	1179	if (@$entries) {
955	push @nondirs, $entry;	1180	for (0 .. $#$entries) {
956	} else {	1181	if ($entries->[$_][1] != DT_DIR) {
957	# need to check for real directory	1182	# splice out directories
958	aioreq_pri $pri;	1183	$dirs = [splice @$entries, 0, $_];
959	add $statgrp aio_lstat "$path/$entry", sub {
960	if (-d _) {
961	push @dirs, $entry;
962
963	unless (--$ndirs) {
964	push @nondirs, @$entries;
965	feed $statgrp;
966	}	1184	last;
967	} else {
968	push @nondirs, $entry;
969	}	1185	}
970	}	1186	}
		1187
		1188	# if we didn't find any non-dir, then all entries are dirs
		1189	unless ($dirs) {
		1190	($dirs, $entries) = ($entries, []);
		1191	}
		1192	} else {
		1193	# directory is empty, so there are no sbdirs
		1194	$dirs = [];
971	}	1195	}
		1196
		1197	# either splice'd the directories out or the dir was empty.
		1198	# convert dents to filenames
		1199	$_ = $_->[0] for @$dirs;
		1200	$_ = $_->[0] for @$entries;
		1201
		1202	return $grp->result ($dirs, $entries);
		1203	}
		1204
		1205	# cannot use, so return to our old ways
		1206	# by pretending we only scanned for names.
		1207	$_ = $_->[0] for @$entries;
		1208	}
		1209
		1210	# stat the dir another time
		1211	aioreq_pri $pri;
		1212	add $grp aio_stat $wd, sub {
		1213	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		1214
		1215	my $ndirs;
		1216
		1217	# take the slow route if anything looks fishy
		1218	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
		1219	$ndirs = -1;
		1220	} else {
		1221	# if nlink == 2, we are finished
		1222	# for non-posix-fs's, we rely on nlink < 2
		1223	$ndirs = (stat _)[3] - 2
		1224	or return $grp->result ([], $entries);
		1225	}
		1226
		1227	my (@dirs, @nondirs);
		1228
		1229	my $statgrp = add $grp aio_group sub {
		1230	$grp->result (\@dirs, \@nondirs);
		1231	};
		1232
		1233	limit $statgrp $maxreq;
		1234	feed $statgrp sub {
		1235	return unless @$entries;
		1236	my $entry = shift @$entries;
		1237
		1238	aioreq_pri $pri;
		1239	$wd->[1] = "$entry/.";
		1240	add $statgrp aio_stat $wd, sub {
		1241	if ($_[0] < 0) {
		1242	push @nondirs, $entry;
		1243	} else {
		1244	# need to check for real directory
		1245	aioreq_pri $pri;
		1246	$wd->[1] = $entry;
		1247	add $statgrp aio_lstat $wd, sub {
		1248	if (-d _) {
		1249	push @dirs, $entry;
		1250
		1251	unless (--$ndirs) {
		1252	push @nondirs, @$entries;
		1253	feed $statgrp;
		1254	}
		1255	} else {
		1256	push @nondirs, $entry;
		1257	}
		1258	}
		1259	}
		1260	};
972	};	1261	};
973	};	1262	};
974	};	1263	};
975	};	1264	};
976	};	1265	};
977		1266
978	$grp	1267	$grp
979	}	1268	}
980		1269
981	=item aio_rmtree $path, $callback->($status)	1270	=item aio_rmtree $pathname, $callback->($status)
982		1271
983	Delete a directory tree starting (and including) C<$path>, return the	1272	Delete a directory tree starting (and including) C<$path>, return the
984	status of the final C<rmdir> only. This is a composite request that	1273	status of the final C<rmdir> only. This is a composite request that
985	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1274	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
986	everything else.	1275	everything else.
987		1276
988	=cut	1277	=cut
989		1278
…		…
1011	};	1300	};
1012		1301
1013	$grp	1302	$grp
1014	}	1303	}
1015		1304
		1305	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1306
		1307	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1308
		1309	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1310	they execute asynchronously and pass the return value to the callback.
		1311
		1312	Both calls can be used for a lot of things, some of which make more sense
		1313	to run asynchronously in their own thread, while some others make less
		1314	sense. For example, calls that block waiting for external events, such
		1315	as locking, will also lock down an I/O thread while it is waiting, which
		1316	can deadlock the whole I/O system. At the same time, there might be no
		1317	alternative to using a thread to wait.
		1318
		1319	So in general, you should only use these calls for things that do
		1320	(filesystem) I/O, not for things that wait for other events (network,
		1321	other processes), although if you are careful and know what you are doing,
		1322	you still can.
		1323
		1324	The following constants are available and can be used for normal C<ioctl>
		1325	and C<fcntl> as well (missing ones are, as usual C<0>):
		1326
		1327	C<F_DUPFD_CLOEXEC>,
		1328
		1329	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1330
		1331	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1332
		1333	C<F_ADD_SEALS>, C<F_GET_SEALS>, C<F_SEAL_SEAL>, C<F_SEAL_SHRINK>, C<F_SEAL_GROW> and
		1334	C<F_SEAL_WRITE>.
		1335
		1336	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1337	C<FS_IOC_FIEMAP>.
		1338
		1339	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1340	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1341
		1342	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1343	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1344	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1345	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1346	C<FS_FL_USER_MODIFIABLE>.
		1347
		1348	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1349	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1350	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1351	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1352
		1353	C<BLKROSET>, C<BLKROGET>, C<BLKRRPART>, C<BLKGETSIZE>, C<BLKFLSBUF>, C<BLKRASET>,
		1354	C<BLKRAGET>, C<BLKFRASET>, C<BLKFRAGET>, C<BLKSECTSET>, C<BLKSECTGET>, C<BLKSSZGET>,
		1355	C<BLKBSZGET>, C<BLKBSZSET>, C<BLKGETSIZE64>,
		1356
		1357
1016	=item aio_sync $callback->($status)	1358	=item aio_sync $callback->($status)
1017		1359
1018	Asynchronously call sync and call the callback when finished.	1360	Asynchronously call sync and call the callback when finished.
1019		1361
1020	=item aio_fsync $fh, $callback->($status)	1362	=item aio_fsync $fh, $callback->($status)
…		…
1027	Asynchronously call fdatasync on the given filehandle and call the	1369	Asynchronously call fdatasync on the given filehandle and call the
1028	callback with the fdatasync result code.	1370	callback with the fdatasync result code.
1029		1371
1030	If this call isn't available because your OS lacks it or it couldn't be	1372	If this call isn't available because your OS lacks it or it couldn't be
1031	detected, it will be emulated by calling C<fsync> instead.	1373	detected, it will be emulated by calling C<fsync> instead.
		1374
		1375	=item aio_syncfs $fh, $callback->($status)
		1376
		1377	Asynchronously call the syncfs syscall to sync the filesystem associated
		1378	to the given filehandle and call the callback with the syncfs result
		1379	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1380	errno to C<ENOSYS> nevertheless.
1032		1381
1033	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1382	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1034		1383
1035	Sync the data portion of the file specified by C<$offset> and C<$length>	1384	Sync the data portion of the file specified by C<$offset> and C<$length>
1036	to disk (but NOT the metadata), by calling the Linux-specific	1385	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1040	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1389	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1041	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1390	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1042	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1391	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1043	manpage for details.	1392	manpage for details.
1044		1393
1045	=item aio_pathsync $path, $callback->($status)	1394	=item aio_pathsync $pathname, $callback->($status)
1046		1395
1047	This request tries to open, fsync and close the given path. This is a	1396	This request tries to open, fsync and close the given path. This is a
1048	composite request intended to sync directories after directory operations	1397	composite request intended to sync directories after directory operations
1049	(E.g. rename). This might not work on all operating systems or have any	1398	(E.g. rename). This might not work on all operating systems or have any
1050	specific effect, but usually it makes sure that directory changes get	1399	specific effect, but usually it makes sure that directory changes get
…		…
1081	};	1430	};
1082		1431
1083	$grp	1432	$grp
1084	}	1433	}
1085		1434
1086	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1435	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1087		1436
1088	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1437	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1089	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1438	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1090	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1439	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1091	scalar must only be modified in-place while an aio operation is pending on	1440	scalar must only be modified in-place while an aio operation is pending on
…		…
1093		1442
1094	It calls the C<msync> function of your OS, if available, with the memory	1443	It calls the C<msync> function of your OS, if available, with the memory
1095	area starting at C<$offset> in the string and ending C<$length> bytes	1444	area starting at C<$offset> in the string and ending C<$length> bytes
1096	later. If C<$length> is negative, counts from the end, and if C<$length>	1445	later. If C<$length> is negative, counts from the end, and if C<$length>
1097	is C<undef>, then it goes till the end of the string. The flags can be	1446	is C<undef>, then it goes till the end of the string. The flags can be
1098	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1447	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1099	C<IO::AIO::MS_SYNC>.	1448	C<IO::AIO::MS_INVALIDATE>.
1100		1449
1101	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1450	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1102		1451
1103	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1452	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1104	scalars.	1453	scalars.
1105		1454
1106	It touches (reads or writes) all memory pages in the specified	1455	It touches (reads or writes) all memory pages in the specified
1107	range inside the scalar. All caveats and parameters are the same	1456	range inside the scalar. All caveats and parameters are the same
1108	as for C<aio_msync>, above, except for flags, which must be either	1457	as for C<aio_msync>, above, except for flags, which must be either
1109	C<0> (which reads all pages and ensures they are instantiated) or	1458	C<0> (which reads all pages and ensures they are instantiated) or
1110	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1459	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1111	writing an octet from it, which dirties the page).	1460	writing an octet from it, which dirties the page).
		1461
		1462	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1463
		1464	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1465	scalars.
		1466
		1467	It reads in all the pages of the underlying storage into memory (if any)
		1468	and locks them, so they are not getting swapped/paged out or removed.
		1469
		1470	If C<$length> is undefined, then the scalar will be locked till the end.
		1471
		1472	On systems that do not implement C<mlock>, this function returns C<-1>
		1473	and sets errno to C<ENOSYS>.
		1474
		1475	Note that the corresponding C<munlock> is synchronous and is
		1476	documented under L<MISCELLANEOUS FUNCTIONS>.
		1477
		1478	Example: open a file, mmap and mlock it - both will be undone when
		1479	C<$data> gets destroyed.
		1480
		1481	open my $fh, "<", $path or die "$path: $!";
		1482	my $data;
		1483	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1484	aio_mlock $data; # mlock in background
		1485
		1486	=item aio_mlockall $flags, $callback->($status)
		1487
		1488	Calls the C<mlockall> function with the given C<$flags> (a
		1489	combination of C<IO::AIO::MCL_CURRENT>, C<IO::AIO::MCL_FUTURE> and
		1490	C<IO::AIO::MCL_ONFAULT>).
		1491
		1492	On systems that do not implement C<mlockall>, this function returns C<-1>
		1493	and sets errno to C<ENOSYS>. Similarly, flag combinations not supported
		1494	by the system result in a return value of C<-1> with errno being set to
		1495	C<EINVAL>.
		1496
		1497	Note that the corresponding C<munlockall> is synchronous and is
		1498	documented under L<MISCELLANEOUS FUNCTIONS>.
		1499
		1500	Example: asynchronously lock all current and future pages into memory.
		1501
		1502	aio_mlockall IO::AIO::MCL_FUTURE;
		1503
		1504	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1505
		1506	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1507	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1508	the ioctl is not available on your OS, then this request will fail with
		1509	C<ENOSYS>.
		1510
		1511	C<$start> is the starting offset to query extents for, C<$length> is the
		1512	size of the range to query - if it is C<undef>, then the whole file will
		1513	be queried.
		1514
		1515	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1516	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1517	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1518	the data portion.
		1519
		1520	C<$count> is the maximum number of extent records to return. If it is
		1521	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1522	case, if it is C<0>, then the callback receives the number of extents
		1523	instead of the extents themselves (which is unreliable, see below).
		1524
		1525	If an error occurs, the callback receives no arguments. The special
		1526	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1527
		1528	Otherwise, the callback receives an array reference with extent
		1529	structures. Each extent structure is an array reference itself, with the
		1530	following members:
		1531
		1532	[$logical, $physical, $length, $flags]
		1533
		1534	Flags is any combination of the following flag values (typically either C<0>
		1535	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1536
		1537	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1538	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1539	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1540	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1541	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1542	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1543
		1544	At the time of this writing (Linux 3.2), this request is unreliable unless
		1545	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1546	it to return all extents of a range for files with a large number of
		1547	extents. The code (only) works around all these issues if C<$count> is
		1548	C<undef>.
1112		1549
1113	=item aio_group $callback->(...)	1550	=item aio_group $callback->(...)
1114		1551
1115	This is a very special aio request: Instead of doing something, it is a	1552	This is a very special aio request: Instead of doing something, it is a
1116	container for other aio requests, which is useful if you want to bundle	1553	container for other aio requests, which is useful if you want to bundle
…		…
1153	like sleep and file handle readable/writable, the overhead this creates is	1590	like sleep and file handle readable/writable, the overhead this creates is
1154	immense (it blocks a thread for a long time) so do not use this function	1591	immense (it blocks a thread for a long time) so do not use this function
1155	except to put your application under artificial I/O pressure.	1592	except to put your application under artificial I/O pressure.
1156		1593
1157	=back	1594	=back
		1595
		1596
		1597	=head2 IO::AIO::WD - multiple working directories
		1598
		1599	Your process only has one current working directory, which is used by all
		1600	threads. This makes it hard to use relative paths (some other component
		1601	could call C<chdir> at any time, and it is hard to control when the path
		1602	will be used by IO::AIO).
		1603
		1604	One solution for this is to always use absolute paths. This usually works,
		1605	but can be quite slow (the kernel has to walk the whole path on every
		1606	access), and can also be a hassle to implement.
		1607
		1608	Newer POSIX systems have a number of functions (openat, fdopendir,
		1609	futimensat and so on) that make it possible to specify working directories
		1610	per operation.
		1611
		1612	For portability, and because the clowns who "designed", or shall I write,
		1613	perpetrated this new interface were obviously half-drunk, this abstraction
		1614	cannot be perfect, though.
		1615
		1616	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1617	object. This object stores the canonicalised, absolute version of the
		1618	path, and on systems that allow it, also a directory file descriptor.
		1619
		1620	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1621	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1622	object and a pathname instead (or the IO::AIO::WD object alone, which
		1623	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1624	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1625	to that IO::AIO::WD object.
		1626
		1627	For example, to get a wd object for F</etc> and then stat F<passwd>
		1628	inside, you would write:
		1629
		1630	aio_wd "/etc", sub {
		1631	my $etcdir = shift;
		1632
		1633	# although $etcdir can be undef on error, there is generally no reason
		1634	# to check for errors here, as aio_stat will fail with ENOENT
		1635	# when $etcdir is undef.
		1636
		1637	aio_stat [$etcdir, "passwd"], sub {
		1638	# yay
		1639	};
		1640	};
		1641
		1642	The fact that C<aio_wd> is a request and not a normal function shows that
		1643	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1644	which is why it is done asynchronously.
		1645
		1646	To stat the directory obtained with C<aio_wd> above, one could write
		1647	either of the following three request calls:
		1648
		1649	aio_lstat "/etc" , sub { ... # pathname as normal string
		1650	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1651	aio_lstat $wd , sub { ... # shorthand for the previous
		1652
		1653	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1654	object and the pathname string, so you could write the following without
		1655	causing any issues due to C<$path> getting reused:
		1656
		1657	my $path = [$wd, undef];
		1658
		1659	for my $name (qw(abc def ghi)) {
		1660	$path->[1] = $name;
		1661	aio_stat $path, sub {
		1662	# ...
		1663	};
		1664	}
		1665
		1666	There are some caveats: when directories get renamed (or deleted), the
		1667	pathname string doesn't change, so will point to the new directory (or
		1668	nowhere at all), while the directory fd, if available on the system,
		1669	will still point to the original directory. Most functions accepting a
		1670	pathname will use the directory fd on newer systems, and the string on
		1671	older systems. Some functions (such as C<aio_realpath>) will always rely on
		1672	the string form of the pathname.
		1673
		1674	So this functionality is mainly useful to get some protection against
		1675	C<chdir>, to easily get an absolute path out of a relative path for future
		1676	reference, and to speed up doing many operations in the same directory
		1677	(e.g. when stat'ing all files in a directory).
		1678
		1679	The following functions implement this working directory abstraction:
		1680
		1681	=over 4
		1682
		1683	=item aio_wd $pathname, $callback->($wd)
		1684
		1685	Asynchonously canonicalise the given pathname and convert it to an
		1686	IO::AIO::WD object representing it. If possible and supported on the
		1687	system, also open a directory fd to speed up pathname resolution relative
		1688	to this working directory.
		1689
		1690	If something goes wrong, then C<undef> is passwd to the callback instead
		1691	of a working directory object and C<$!> is set appropriately. Since
		1692	passing C<undef> as working directory component of a pathname fails the
		1693	request with C<ENOENT>, there is often no need for error checking in the
		1694	C<aio_wd> callback, as future requests using the value will fail in the
		1695	expected way.
		1696
		1697	=item IO::AIO::CWD
		1698
		1699	This is a compile time constant (object) that represents the process
		1700	current working directory.
		1701
		1702	Specifying this object as working directory object for a pathname is as if
		1703	the pathname would be specified directly, without a directory object. For
		1704	example, these calls are functionally identical:
		1705
		1706	aio_stat "somefile", sub { ... };
		1707	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1708
		1709	=back
		1710
		1711	To recover the path associated with an IO::AIO::WD object, you can use
		1712	C<aio_realpath>:
		1713
		1714	aio_realpath $wd, sub {
		1715	warn "path is $_[0]\n";
		1716	};
		1717
		1718	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1719	sometimes, fall back to using an absolue path.
1158		1720
1159	=head2 IO::AIO::REQ CLASS	1721	=head2 IO::AIO::REQ CLASS
1160		1722
1161	All non-aggregate C<aio_*> functions return an object of this class when	1723	All non-aggregate C<aio_*> functions return an object of this class when
1162	called in non-void context.	1724	called in non-void context.
…		…
1280		1842
1281	Sets a feeder/generator on this group: every group can have an attached	1843	Sets a feeder/generator on this group: every group can have an attached
1282	generator that generates requests if idle. The idea behind this is that,	1844	generator that generates requests if idle. The idea behind this is that,
1283	although you could just queue as many requests as you want in a group,	1845	although you could just queue as many requests as you want in a group,
1284	this might starve other requests for a potentially long time. For example,	1846	this might starve other requests for a potentially long time. For example,
1285	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1847	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1286	delaying any later requests for a long time.	1848	requests, delaying any later requests for a long time.
1287		1849
1288	To avoid this, and allow incremental generation of requests, you can	1850	To avoid this, and allow incremental generation of requests, you can
1289	instead a group and set a feeder on it that generates those requests. The	1851	instead a group and set a feeder on it that generates those requests. The
1290	feed callback will be called whenever there are few enough (see C<limit>,	1852	feed callback will be called whenever there are few enough (see C<limit>,
1291	below) requests active in the group itself and is expected to queue more	1853	below) requests active in the group itself and is expected to queue more
…		…
1323	The default value for the limit is C<0>, but note that setting a feeder	1885	The default value for the limit is C<0>, but note that setting a feeder
1324	automatically bumps it up to C<2>.	1886	automatically bumps it up to C<2>.
1325		1887
1326	=back	1888	=back
1327		1889
		1890
1328	=head2 SUPPORT FUNCTIONS	1891	=head2 SUPPORT FUNCTIONS
1329		1892
1330	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1893	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1331		1894
1332	=over 4	1895	=over 4
…		…
1340		1903
1341	See C<poll_cb> for an example.	1904	See C<poll_cb> for an example.
1342		1905
1343	=item IO::AIO::poll_cb	1906	=item IO::AIO::poll_cb
1344		1907
1345	Process some outstanding events on the result pipe. You have to call this	1908	Process some requests that have reached the result phase (i.e. they have
1346	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1909	been executed but the results are not yet reported). You have to call
1347	returned earlier for whatever reason. Returns immediately when no events	1910	this "regularly" to finish outstanding requests.
1348	are outstanding. The amount of events processed depends on the settings of
1349	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1350		1911
		1912	Returns C<0> if all events could be processed (or there were no
		1913	events to process), or C<-1> if it returned earlier for whatever
		1914	reason. Returns immediately when no events are outstanding. The amount
		1915	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
		1916	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
		1917
1351	If not all requests were processed for whatever reason, the filehandle	1918	If not all requests were processed for whatever reason, the poll file
1352	will still be ready when C<poll_cb> returns, so normally you don't have to	1919	descriptor will still be ready when C<poll_cb> returns, so normally you
1353	do anything special to have it called later.	1920	don't have to do anything special to have it called later.
		1921
		1922	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1923	ready, it can be beneficial to call this function from loops which submit
		1924	a lot of requests, to make sure the results get processed when they become
		1925	available and not just when the loop is finished and the event loop takes
		1926	over again. This function returns very fast when there are no outstanding
		1927	requests.
1354		1928
1355	Example: Install an Event watcher that automatically calls	1929	Example: Install an Event watcher that automatically calls
1356	IO::AIO::poll_cb with high priority (more examples can be found in the	1930	IO::AIO::poll_cb with high priority (more examples can be found in the
1357	SYNOPSIS section, at the top of this document):	1931	SYNOPSIS section, at the top of this document):
1358		1932
…		…
1360	poll => 'r', async => 1,	1934	poll => 'r', async => 1,
1361	cb => \&IO::AIO::poll_cb);	1935	cb => \&IO::AIO::poll_cb);
1362		1936
1363	=item IO::AIO::poll_wait	1937	=item IO::AIO::poll_wait
1364		1938
1365	If there are any outstanding requests and none of them in the result	1939	Wait until either at least one request is in the result phase or no
1366	phase, wait till the result filehandle becomes ready for reading (simply	1940	requests are outstanding anymore.
1367	does a C<select> on the filehandle. This is useful if you want to	1941
1368	synchronously wait for some requests to finish).	1942	This is useful if you want to synchronously wait for some requests to
		1943	become ready, without actually handling them.
1369		1944
1370	See C<nreqs> for an example.	1945	See C<nreqs> for an example.
1371		1946
1372	=item IO::AIO::poll	1947	=item IO::AIO::poll
1373		1948
…		…
1384		1959
1385	Strictly equivalent to:	1960	Strictly equivalent to:
1386		1961
1387	IO::AIO::poll_wait, IO::AIO::poll_cb	1962	IO::AIO::poll_wait, IO::AIO::poll_cb
1388	while IO::AIO::nreqs;	1963	while IO::AIO::nreqs;
		1964
		1965	This function can be useful at program aborts, to make sure outstanding
		1966	I/O has been done (C<IO::AIO> uses an C<END> block which already calls
		1967	this function on normal exits), or when you are merely using C<IO::AIO>
		1968	for its more advanced functions, rather than for async I/O, e.g.:
		1969
		1970	my ($dirs, $nondirs);
		1971	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1972	IO::AIO::flush;
		1973	# $dirs, $nondirs are now set
1389		1974
1390	=item IO::AIO::max_poll_reqs $nreqs	1975	=item IO::AIO::max_poll_reqs $nreqs
1391		1976
1392	=item IO::AIO::max_poll_time $seconds	1977	=item IO::AIO::max_poll_time $seconds
1393		1978
…		…
1420	poll => 'r', nice => 1,	2005	poll => 'r', nice => 1,
1421	cb => &IO::AIO::poll_cb);	2006	cb => &IO::AIO::poll_cb);
1422		2007
1423	=back	2008	=back
1424		2009
		2010
1425	=head3 CONTROLLING THE NUMBER OF THREADS	2011	=head3 CONTROLLING THE NUMBER OF THREADS
1426		2012
1427	=over	2013	=over
1428		2014
1429	=item IO::AIO::min_parallel $nthreads	2015	=item IO::AIO::min_parallel $nthreads
…		…
1460		2046
1461	Under normal circumstances you don't need to call this function.	2047	Under normal circumstances you don't need to call this function.
1462		2048
1463	=item IO::AIO::max_idle $nthreads	2049	=item IO::AIO::max_idle $nthreads
1464		2050
1465	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	2051	Limit the number of threads (default: 4) that are allowed to idle
1466	threads that did not get a request to process within 10 seconds). That	2052	(i.e., threads that did not get a request to process within the idle
1467	means if a thread becomes idle while C<$nthreads> other threads are also	2053	timeout (default: 10 seconds). That means if a thread becomes idle while
1468	idle, it will free its resources and exit.	2054	C<$nthreads> other threads are also idle, it will free its resources and
		2055	exit.
1469		2056
1470	This is useful when you allow a large number of threads (e.g. 100 or 1000)	2057	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1471	to allow for extremely high load situations, but want to free resources	2058	to allow for extremely high load situations, but want to free resources
1472	under normal circumstances (1000 threads can easily consume 30MB of RAM).	2059	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1473		2060
1474	The default is probably ok in most situations, especially if thread	2061	The default is probably ok in most situations, especially if thread
1475	creation is fast. If thread creation is very slow on your system you might	2062	creation is fast. If thread creation is very slow on your system you might
1476	want to use larger values.	2063	want to use larger values.
1477		2064
		2065	=item IO::AIO::idle_timeout $seconds
		2066
		2067	Sets the minimum idle timeout (default 10) after which worker threads are
		2068	allowed to exit. SEe C<IO::AIO::max_idle>.
		2069
1478	=item IO::AIO::max_outstanding $maxreqs	2070	=item IO::AIO::max_outstanding $maxreqs
1479		2071
1480	This is a very bad function to use in interactive programs because it
1481	blocks, and a bad way to reduce concurrency because it is inexact: Better
1482	use an C<aio_group> together with a feed callback.
1483
1484	Sets the maximum number of outstanding requests to C<$nreqs>. If you	2072	Sets the maximum number of outstanding requests to C<$nreqs>. If
1485	do queue up more than this number of requests, the next call to the	2073	you do queue up more than this number of requests, the next call to
1486	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)	2074	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
1487	function will block until the limit is no longer exceeded.	2075	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		2076	longer exceeded.
1488		2077
1489	The default value is very large, so there is no practical limit on the	2078	In other words, this setting does not enforce a queue limit, but can be
1490	number of outstanding requests.	2079	used to make poll functions block if the limit is exceeded.
1491		2080
1492	You can still queue as many requests as you want. Therefore,	2081	This is a bad function to use in interactive programs because it blocks,
1493	C<max_outstanding> is mainly useful in simple scripts (with low values) or	2082	and a bad way to reduce concurrency because it is inexact. If you need to
1494	as a stop gap to shield against fatal memory overflow (with large values).	2083	issue many requests without being able to call a poll function on demand,
		2084	it is better to use an C<aio_group> together with a feed callback.
		2085
		2086	Its main use is in scripts without an event loop - when you want to stat a
		2087	lot of files, you can write something like this:
		2088
		2089	IO::AIO::max_outstanding 32;
		2090
		2091	for my $path (...) {
		2092	aio_stat $path , ...;
		2093	IO::AIO::poll_cb;
		2094	}
		2095
		2096	IO::AIO::flush;
		2097
		2098	The call to C<poll_cb> inside the loop will normally return instantly,
		2099	allowing the loop to progress, but as soon as more than C<32> requests
		2100	are in-flight, it will block until some requests have been handled. This
		2101	keeps the loop from pushing a large number of C<aio_stat> requests onto
		2102	the queue (which, with many paths to stat, can use up a lot of memory).
		2103
		2104	The default value for C<max_outstanding> is very large, so there is no
		2105	practical limit on the number of outstanding requests.
1495		2106
1496	=back	2107	=back
		2108
1497		2109
1498	=head3 STATISTICAL INFORMATION	2110	=head3 STATISTICAL INFORMATION
1499		2111
1500	=over	2112	=over
1501		2113
…		…
1519	Returns the number of requests currently in the pending state (executed,	2131	Returns the number of requests currently in the pending state (executed,
1520	but not yet processed by poll_cb).	2132	but not yet processed by poll_cb).
1521		2133
1522	=back	2134	=back
1523		2135
		2136
		2137	=head3 SUBSECOND STAT TIME ACCESS
		2138
		2139	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2140	generally find access/modification and change times with subsecond time
		2141	accuracy of the system supports it, but perl's built-in functions only
		2142	return the integer part.
		2143
		2144	The following functions return the timestamps of the most recent
		2145	stat with subsecond precision on most systems and work both after
		2146	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2147	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2148	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2149
		2150	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2151	full resolution without rounding and work with standard perl C<stat>,
		2152	alleviating the need to call the special C<Time::HiRes> functions, which
		2153	do not act like their perl counterparts.
		2154
		2155	On operating systems or file systems where subsecond time resolution is
		2156	not supported or could not be detected, a fractional part of C<0> is
		2157	returned, so it is always safe to call these functions.
		2158
		2159	=over 4
		2160
		2161	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		2162
		2163	Return the access, modication, change or birth time, respectively,
		2164	including fractional part. Due to the limited precision of floating point,
		2165	the accuracy on most platforms is only a bit better than milliseconds
		2166	for times around now - see the I<nsec> function family, below, for full
		2167	accuracy.
		2168
		2169	File birth time is only available when the OS and perl support it (on
		2170	FreeBSD and NetBSD at the time of this writing, although support is
		2171	adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
		2172	it). On systems where it isn't available, C<0> is currently returned, but
		2173	this might change to C<undef> in a future version.
		2174
		2175	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		2176
		2177	Returns access, modification, change and birth time all in one go, and
		2178	maybe more times in the future version.
		2179
		2180	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		2181
		2182	Return the fractional access, modifcation, change or birth time, in nanoseconds,
		2183	as an integer in the range C<0> to C<999999999>.
		2184
		2185	Note that no accessors are provided for access, modification and
		2186	change times - you need to get those from C<stat _> if required (C<int
		2187	IO::AIO::st_atime> and so on will I<not> generally give you the correct
		2188	value).
		2189
		2190	=item $seconds = IO::AIO::st_btimesec
		2191
		2192	The (integral) seconds part of the file birth time, if available.
		2193
		2194	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		2195
		2196	Like the functions above, but returns all four times in one go (and maybe
		2197	more in future versions).
		2198
		2199	=item $counter = IO::AIO::st_gen
		2200
		2201	Returns the generation counter (in practice this is just a random number)
		2202	of the file. This is only available on platforms which have this member in
		2203	their C<struct stat> (most BSDs at the time of this writing) and generally
		2204	only to the root usert. If unsupported, C<0> is returned, but this might
		2205	change to C<undef> in a future version.
		2206
		2207	=back
		2208
		2209	Example: print the high resolution modification time of F</etc>, using
		2210	C<stat>, and C<IO::AIO::aio_stat>.
		2211
		2212	if (stat "/etc") {
		2213	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2214	}
		2215
		2216	IO::AIO::aio_stat "/etc", sub {
		2217	$_[0]
		2218	and return;
		2219
		2220	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2221	};
		2222
		2223	IO::AIO::flush;
		2224
		2225	Output of the awbove on my system, showing reduced and full accuracy:
		2226
		2227	stat(/etc) mtime: 1534043702.020808
		2228	aio_stat(/etc) mtime: 1534043702.020807792
		2229
		2230
1524	=head3 MISCELLANEOUS FUNCTIONS	2231	=head3 MISCELLANEOUS FUNCTIONS
1525		2232
1526	IO::AIO implements some functions that might be useful, but are not	2233	IO::AIO implements some functions that are useful when you want to use
1527	asynchronous.	2234	some "Advanced I/O" function not available to in Perl, without going the
		2235	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2236	counterpart.
1528		2237
1529	=over 4	2238	=over 4
		2239
		2240	=item $retval = IO::AIO::fexecve $fh, $argv, $envp
		2241
		2242	A more-or-less direct equivalent to the POSIX C<fexecve> functions, which
		2243	allows you to specify the program to be executed via a file descriptor (or
		2244	handle). Returns C<-1> and sets errno to C<ENOSYS> if not available.
		2245
		2246	=item $retval = IO::AIO::mount $special, $path, $fstype, $flags = 0, $data = undef
		2247
		2248	Calls the GNU/Linux mount syscall with the given arguments. All except
		2249	C<$flags> are strings, and if C<$data> is C<undef>, a C<NULL> will be
		2250	passed.
		2251
		2252	The following values for C<$flags> are available:
		2253
		2254	C<IO::AIO::MS_RDONLY>, C<IO::AIO::MS_NOSUID>, C<IO::AIO::MS_NODEV>, C<IO::AIO::MS_NOEXEC>, C<IO::AIO::MS_SYNCHRONOUS>,
		2255	C<IO::AIO::MS_REMOUNT>, C<IO::AIO::MS_MANDLOCK>, C<IO::AIO::MS_DIRSYNC>, C<IO::AIO::MS_NOATIME>,
		2256	C<IO::AIO::MS_NODIRATIME>, C<IO::AIO::MS_BIND>, C<IO::AIO::MS_MOVE>, C<IO::AIO::MS_REC>, C<IO::AIO::MS_SILENT>,
		2257	C<IO::AIO::MS_POSIXACL>, C<IO::AIO::MS_UNBINDABLE>, C<IO::AIO::MS_PRIVATE>, C<IO::AIO::MS_SLAVE>, C<IO::AIO::MS_SHARED>,
		2258	C<IO::AIO::MS_RELATIME>, C<IO::AIO::MS_KERNMOUNT>, C<IO::AIO::MS_I_VERSION>, C<IO::AIO::MS_STRICTATIME>,
		2259	C<IO::AIO::MS_LAZYTIME>, C<IO::AIO::MS_ACTIVE>, C<IO::AIO::MS_NOUSER>, C<IO::AIO::MS_RMT_MASK>, C<IO::AIO::MS_MGC_VAL> and
		2260	C<IO::AIO::MS_MGC_MSK>.
		2261
		2262	=item $retval = IO::AIO::umount $path, $flags = 0
		2263
		2264	Invokes the GNU/Linux C<umount> or C<umount2> syscalls. Always calls
		2265	C<umount> if C<$flags> is C<0>, otherwqise always tries to call
		2266	C<umount2>.
		2267
		2268	The following C<$flags> are available:
		2269
		2270	C<IO::AIO::MNT_FORCE>, C<IO::AIO::MNT_DETACH>, C<IO::AIO::MNT_EXPIRE> and C<IO::AIO::UMOUNT_NOFOLLOW>.
		2271
		2272	=item $numfd = IO::AIO::get_fdlimit
		2273
		2274	Tries to find the current file descriptor limit and returns it, or
		2275	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2276	the highest valid file descriptor number.
		2277
		2278	=item IO::AIO::min_fdlimit [$numfd]
		2279
		2280	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2281	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2282	is missing, it will try to set a very high limit, although this is not
		2283	recommended when you know the actual minimum that you require.
		2284
		2285	If the limit cannot be raised enough, the function makes a best-effort
		2286	attempt to increase the limit as much as possible, using various
		2287	tricks, while still failing. You can query the resulting limit using
		2288	C<IO::AIO::get_fdlimit>.
		2289
		2290	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2291	true.
1530		2292
1531	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2293	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1532		2294
1533	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2295	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1534	but is blocking (this makes most sense if you know the input data is	2296	but is blocking (this makes most sense if you know the input data is
…		…
1537		2299
1538	Returns the number of bytes copied, or C<-1> on error.	2300	Returns the number of bytes copied, or C<-1> on error.
1539		2301
1540	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2302	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1541		2303
1542	Simply calls the C<posix_fadvise> function (see it's	2304	Simply calls the C<posix_fadvise> function (see its
1543	manpage for details). The following advice constants are	2305	manpage for details). The following advice constants are
1544	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2306	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1545	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2307	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1546	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2308	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1547		2309
1548	On systems that do not implement C<posix_fadvise>, this function returns	2310	On systems that do not implement C<posix_fadvise>, this function returns
1549	ENOSYS, otherwise the return value of C<posix_fadvise>.	2311	ENOSYS, otherwise the return value of C<posix_fadvise>.
1550		2312
		2313	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		2314
		2315	Simply calls the C<posix_madvise> function (see its
		2316	manpage for details). The following advice constants are
		2317	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		2318	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2319	C<IO::AIO::MADV_DONTNEED>.
		2320
		2321	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2322	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2323	will be reduced to fit into the C<$scalar>.
		2324
		2325	On systems that do not implement C<posix_madvise>, this function returns
		2326	ENOSYS, otherwise the return value of C<posix_madvise>.
		2327
		2328	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		2329
		2330	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		2331	$scalar (see its manpage for details). The following protect
		2332	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		2333	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2334
		2335	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2336	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2337	will be reduced to fit into the C<$scalar>.
		2338
		2339	On systems that do not implement C<mprotect>, this function returns
		2340	ENOSYS, otherwise the return value of C<mprotect>.
		2341
1551	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2342	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1552		2343
1553	Memory-maps a file (or anonymous memory range) and attaches it to the	2344	Memory-maps a file (or anonymous memory range) and attaches it to the
1554	given C<$scalar>, which will act like a string scalar.	2345	given C<$scalar>, which will act like a string scalar. Returns true on
		2346	success, and false otherwise.
1555		2347
		2348	The scalar must exist, but its contents do not matter - this means you
		2349	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2350	the scalar first.
		2351
1556	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2352	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1557	change the string length, and most read-only operations such as copying it	2353	which don't change the string length, and most read-only operations such
1558	or searching it with regexes and so on.	2354	as copying it or searching it with regexes and so on.
1559		2355
1560	Anything else is unsafe and will, at best, result in memory leaks.	2356	Anything else is unsafe and will, at best, result in memory leaks.
1561		2357
1562	The memory map associated with the C<$scalar> is automatically removed	2358	The memory map associated with the C<$scalar> is automatically removed
1563	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2359	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1564	C<IO::AIO::munmap> functions are called.	2360	or C<IO::AIO::munmap> functions are called on it.
1565		2361
1566	This calls the C<mmap>(2) function internally. See your system's manual	2362	This calls the C<mmap>(2) function internally. See your system's manual
1567	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2363	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1568		2364
1569	The C<$length> must be larger than zero and smaller than the actual	2365	The C<$length> must be larger than zero and smaller than the actual
1570	filesize.	2366	filesize.
1571		2367
1572	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2368	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1573	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2369	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1574		2370
1575	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2371	C<$flags> can be a combination of
1576	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2372	C<IO::AIO::MAP_SHARED> or
1577	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2373	C<IO::AIO::MAP_PRIVATE>,
		2374	or a number of system-specific flags (when not available, the are C<0>):
1578	(which is set to C<MAP_ANON> if your system only provides this	2375	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1579	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2376	C<IO::AIO::MAP_LOCKED>,
1580	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2377	C<IO::AIO::MAP_NORESERVE>,
		2378	C<IO::AIO::MAP_POPULATE>,
1581	C<IO::AIO::MAP_NONBLOCK>	2379	C<IO::AIO::MAP_NONBLOCK>,
		2380	C<IO::AIO::MAP_FIXED>,
		2381	C<IO::AIO::MAP_GROWSDOWN>,
		2382	C<IO::AIO::MAP_32BIT>,
		2383	C<IO::AIO::MAP_HUGETLB>,
		2384	C<IO::AIO::MAP_STACK>,
		2385	C<IO::AIO::MAP_FIXED_NOREPLACE>,
		2386	C<IO::AIO::MAP_SHARED_VALIDATE>,
		2387	C<IO::AIO::MAP_SYNC> or
		2388	C<IO::AIO::MAP_UNINITIALIZED>.
1582		2389
1583	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2390	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1584		2391
		2392	C<$offset> is the offset from the start of the file - it generally must be
		2393	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		2394
		2395	Example:
		2396
		2397	use Digest::MD5;
		2398	use IO::AIO;
		2399
		2400	open my $fh, "<verybigfile"
		2401	or die "$!";
		2402
		2403	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		2404	or die "verybigfile: $!";
		2405
		2406	my $fast_md5 = md5 $data;
		2407
1585	=item IO::AIO::munmap $scalar	2408	=item IO::AIO::munmap $scalar
1586		2409
1587	Removes a previous mmap and undefines the C<$scalar>.	2410	Removes a previous mmap and undefines the C<$scalar>.
1588		2411
		2412	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2413
		2414	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2415	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2416	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2417
		2418	Returns true if successful, and false otherwise. If the underlying mmapped
		2419	region has changed address, then the true value has the numerical value
		2420	C<1>, otherwise it has the numerical value C<0>:
		2421
		2422	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2423	or die "mremap: $!";
		2424
		2425	if ($success*1) {
		2426	warn "scalar has chanegd address in memory\n";
		2427	}
		2428
		2429	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2430	implemented, but not supported and might go away in a future version.
		2431
		2432	On systems where this call is not supported or is not emulated, this call
		2433	returns falls and sets C<$!> to C<ENOSYS>.
		2434
1589	=item IO::AIO::mlockall $flags	2435	=item IO::AIO::mlockall $flags
1590		2436
1591	Calls the C<mlockall> function with the given C<$flags> (a combination of	2437	Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
1592	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL__FUTURE>).	2438	but is blocking.
1593		2439
1594	On systems that do not implement C<mlockall>, this function returns	2440	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1595	ENOSYS, otherwise the return value of C<mlockall>.	2441
		2442	Calls the C<munlock> function, undoing the effects of a previous
		2443	C<aio_mlock> call (see its description for details).
1596		2444
1597	=item IO::AIO::munlockall	2445	=item IO::AIO::munlockall
1598		2446
1599	Calls the C<munlockall> function.	2447	Calls the C<munlockall> function.
1600		2448
1601	On systems that do not implement C<munlockall>, this function returns	2449	On systems that do not implement C<munlockall>, this function returns
1602	ENOSYS, otherwise the return value of C<munlockall>.	2450	ENOSYS, otherwise the return value of C<munlockall>.
		2451
		2452	=item $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		2453
		2454	Uses the GNU/Linux C<accept4(2)> syscall, if available, to accept a socket
		2455	and return the new file handle on success, or sets C<$!> and returns
		2456	C<undef> on error.
		2457
		2458	The remote name of the new socket will be stored in C<$sockaddr>, which
		2459	will be extended to allow for at least C<$sockaddr_maxlen> octets. If the
		2460	socket name does not fit into C<$sockaddr_maxlen> octets, this is signaled
		2461	by returning a longer string in C<$sockaddr>, which might or might not be
		2462	truncated.
		2463
		2464	To accept name-less sockets, use C<undef> for C<$sockaddr> and C<0> for
		2465	C<$sockaddr_maxlen>.
		2466
		2467	The main reasons to use this syscall rather than portable C<accept(2)>
		2468	are that you can specify C<SOCK_NONBLOCK> and/or C<SOCK_CLOEXEC>
		2469	flags and you can accept name-less sockets by specifying C<0> for
		2470	C<$sockaddr_maxlen>, which is sadly not possible with perl's interface to
		2471	C<accept>.
		2472
		2473	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2474
		2475	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2476	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2477	should be the file offset.
		2478
		2479	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2480	silently corrupt the data in this case.
		2481
		2482	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2483	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2484	C<IO::AIO::SPLICE_F_GIFT>.
		2485
		2486	See the C<splice(2)> manpage for details.
		2487
		2488	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2489
		2490	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2491	description for C<IO::AIO::splice> above for details.
		2492
		2493	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2494
		2495	Attempts to query or change the pipe buffer size. Obviously works only
		2496	on pipes, and currently works only on GNU/Linux systems, and fails with
		2497	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2498	size on other systems, drop me a note.
		2499
		2500	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2501
		2502	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2503	C<$flags> is missing or C<0>, then this should be the same as a call to
		2504	perl's built-in C<pipe> function and create a new pipe, and works on
		2505	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2506	(..., 4096, O_BINARY)>.
		2507
		2508	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2509	the given flags (Linux 2.6.27, glibc 2.9).
		2510
		2511	On success, the read and write file handles are returned.
		2512
		2513	On error, nothing will be returned. If the pipe2 syscall is missing and
		2514	C<$flags> is non-zero, fails with C<ENOSYS>.
		2515
		2516	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2517	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2518	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2519
		2520	Example: create a pipe race-free w.r.t. threads and fork:
		2521
		2522	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2523	or die "pipe2: $!\n";
		2524
		2525	=item $fh = IO::AIO::memfd_create $pathname[, $flags]
		2526
		2527	This is a direct interface to the Linux L<memfd_create(2)> system
		2528	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2529	should be C<IO::AIO::MFD_CLOEXEC>.
		2530
		2531	On success, the new memfd filehandle is returned, otherwise returns
		2532	C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
		2533
		2534	Please refer to L<memfd_create(2)> for more info on this call.
		2535
		2536	The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
		2537	C<IO::AIO::MFD_ALLOW_SEALING>, C<IO::AIO::MFD_HUGETLB>,
		2538	C<IO::AIO::MFD_HUGETLB_2MB> and C<IO::AIO::MFD_HUGETLB_1GB>.
		2539
		2540	Example: create a new memfd.
		2541
		2542	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2543	or die "memfd_create: $!\n";
		2544
		2545	=item $fh = IO::AIO::pidfd_open $pid[, $flags]
		2546
		2547	This is an interface to the Linux L<pidfd_open(2)> system call. The
		2548	default for C<$flags> is C<0>.
		2549
		2550	On success, a new pidfd filehandle is returned (that is already set to
		2551	close-on-exec), otherwise returns C<undef>. If the syscall is missing,
		2552	fails with C<ENOSYS>.
		2553
		2554	Example: open pid 6341 as pidfd.
		2555
		2556	my $fh = IO::AIO::pidfd_open 6341
		2557	or die "pidfd_open: $!\n";
		2558
		2559	=item $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		2560
		2561	This is an interface to the Linux L<pidfd_send_signal> system call. The
		2562	default for C<$siginfo> is C<undef> and the default for C<$flags> is C<0>.
		2563
		2564	Returns the system call status. If the syscall is missing, fails with
		2565	C<ENOSYS>.
		2566
		2567	When specified, C<$siginfo> must be a reference to a hash with one or more
		2568	of the following members:
		2569
		2570	=over
		2571
		2572	=item code - the C<si_code> member
		2573
		2574	=item pid - the C<si_pid> member
		2575
		2576	=item uid - the C<si_uid> member
		2577
		2578	=item value_int - the C<si_value.sival_int> member
		2579
		2580	=item value_ptr - the C<si_value.sival_ptr> member, specified as an integer
		2581
		2582	=back
		2583
		2584	Example: send a SIGKILL to the specified process.
		2585
		2586	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
		2587	and die "pidfd_send_signal: $!\n";
		2588
		2589	Example: send a SIGKILL to the specified process with extra data.
		2590
		2591	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
		2592	and die "pidfd_send_signal: $!\n";
		2593
		2594	=item $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		2595
		2596	This is an interface to the Linux L<pidfd_getfd> system call. The default
		2597	for C<$flags> is C<0>.
		2598
		2599	On success, returns a dup'ed copy of the target file descriptor (specified
		2600	as an integer) returned (that is already set to close-on-exec), otherwise
		2601	returns C<undef>. If the syscall is missing, fails with C<ENOSYS>.
		2602
		2603	Example: get a copy of standard error of another process and print soemthing to it.
		2604
		2605	my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
		2606	or die "pidfd_getfd: $!\n";
		2607	print $errfh "stderr\n";
		2608
		2609	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2610
		2611	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2612	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2613
		2614	On success, the new eventfd filehandle is returned, otherwise returns
		2615	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2616
		2617	Please refer to L<eventfd(2)> for more info on this call.
		2618
		2619	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2620	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2621
		2622	Example: create a new eventfd filehandle:
		2623
		2624	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2625	or die "eventfd: $!\n";
		2626
		2627	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2628
		2629	This is a direct interface to the Linux L<timerfd_create(2)> system
		2630	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2631	should be C<IO::AIO::TFD_CLOEXEC>.
		2632
		2633	On success, the new timerfd filehandle is returned, otherwise returns
		2634	C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
		2635
		2636	Please refer to L<timerfd_create(2)> for more info on this call.
		2637
		2638	The following C<$clockid> values are
		2639	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2640	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2641	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2642	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2643
		2644	The following C<$flags> values are available (Linux
		2645	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2646
		2647	Example: create a new timerfd and set it to one-second repeated alarms,
		2648	then wait for two alarms:
		2649
		2650	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2651	or die "timerfd_create: $!\n";
		2652
		2653	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2654	or die "timerfd_settime: $!\n";
		2655
		2656	for (1..2) {
		2657	8 == sysread $fh, my $buf, 8
		2658	or die "timerfd read failure\n";
		2659
		2660	printf "number of expirations (likely 1): %d\n",
		2661	unpack "Q", $buf;
		2662	}
		2663
		2664	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2665
		2666	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2667	call. Please refer to its manpage for more info on this call.
		2668
		2669	The new itimerspec is specified using two (possibly fractional) second
		2670	values, C<$new_interval> and C<$new_value>).
		2671
		2672	On success, the current interval and value are returned (as per
		2673	C<timerfd_gettime>). On failure, the empty list is returned.
		2674
		2675	The following C<$flags> values are
		2676	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2677	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2678
		2679	See C<IO::AIO::timerfd_create> for a full example.
		2680
		2681	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2682
		2683	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2684	call. Please refer to its manpage for more info on this call.
		2685
		2686	On success, returns the current values of interval and value for the given
		2687	timerfd (as potentially fractional second values). On failure, the empty
		2688	list is returned.
1603		2689
1604	=back	2690	=back
1605		2691
1606	=cut	2692	=cut
1607		2693
…		…
1642	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	2728	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1643	\&IO::AIO::poll_cb);	2729	\&IO::AIO::poll_cb);
1644		2730
1645	=head2 FORK BEHAVIOUR	2731	=head2 FORK BEHAVIOUR
1646		2732
1647	This module should do "the right thing" when the process using it forks:	2733	Usage of pthreads in a program changes the semantics of fork
		2734	considerably. Specifically, only async-safe functions can be called after
		2735	fork. Perl doesn't know about this, so in general, you cannot call fork
		2736	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2737	pthreads, so this applies, but many other extensions and (for inexplicable
		2738	reasons) perl itself often is linked against pthreads, so this limitation
		2739	applies to quite a lot of perls.
1648		2740
1649	Before the fork, IO::AIO enters a quiescent state where no requests	2741	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1650	can be added in other threads and no results will be processed. After	2742	only works in the process that loaded it. Forking is fully supported, but
1651	the fork the parent simply leaves the quiescent state and continues	2743	using IO::AIO in the child is not.
1652	request/result processing, while the child frees the request/result queue
1653	(so that the requests started before the fork will only be handled in the
1654	parent). Threads will be started on demand until the limit set in the
1655	parent process has been reached again.
1656		2744
1657	In short: the parent will, after a short pause, continue as if fork had	2745	You might get around by not I<using> IO::AIO before (or after)
1658	not been called, while the child will act as if IO::AIO has not been used	2746	forking. You could also try to call the L<IO::AIO::reinit> function in the
1659	yet.	2747	child:
		2748
		2749	=over 4
		2750
		2751	=item IO::AIO::reinit
		2752
		2753	Abandons all current requests and I/O threads and simply reinitialises all
		2754	data structures. This is not an operation supported by any standards, but
		2755	happens to work on GNU/Linux and some newer BSD systems.
		2756
		2757	The only reasonable use for this function is to call it after forking, if
		2758	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2759	the process will result in undefined behaviour. Calling it at any time
		2760	will also result in any undefined (by POSIX) behaviour.
		2761
		2762	=back
		2763
		2764	=head2 LINUX-SPECIFIC CALLS
		2765
		2766	When a call is documented as "linux-specific" then this means it
		2767	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2768	availability and compatibility of such calls regardless of the platform
		2769	it is compiled on, so platforms such as FreeBSD which often implement
		2770	these calls will work. When in doubt, call them and see if they fail wth
		2771	C<ENOSYS>.
1660		2772
1661	=head2 MEMORY USAGE	2773	=head2 MEMORY USAGE
1662		2774
1663	Per-request usage:	2775	Per-request usage:
1664		2776
…		…
1677	temporary buffers, and each thread requires a stack and other data	2789	temporary buffers, and each thread requires a stack and other data
1678	structures (usually around 16k-128k, depending on the OS).	2790	structures (usually around 16k-128k, depending on the OS).
1679		2791
1680	=head1 KNOWN BUGS	2792	=head1 KNOWN BUGS
1681		2793
1682	Known bugs will be fixed in the next release.	2794	Known bugs will be fixed in the next release :)
		2795
		2796	=head1 KNOWN ISSUES
		2797
		2798	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2799	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2800	non-created hash slots or other scalars I didn't think of. It's best to
		2801	avoid such and either use scalar variables or making sure that the scalar
		2802	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2803
		2804	I am not sure anything can be done about this, so this is considered a
		2805	known issue, rather than a bug.
1683		2806
1684	=head1 SEE ALSO	2807	=head1 SEE ALSO
1685		2808
1686	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2809	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1687	more natural syntax.	2810	more natural syntax and L<IO::FDPass> for file descriptor passing.
1688		2811
1689	=head1 AUTHOR	2812	=head1 AUTHOR
1690		2813
1691	Marc Lehmann <schmorp@schmorp.de>	2814	Marc Lehmann <schmorp@schmorp.de>
1692	http://home.schmorp.de/	2815	http://home.schmorp.de/

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