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Revision 1.212 by root, Thu Sep 29 22:42:15 2011 UTC vs.
Revision 1.319 by root, Wed Sep 27 03:09:57 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
…		…
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;
…		…
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 = '4.0';	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_realpath aio_sync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate	181	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
179	aio_pathsync aio_readahead	182	aio_pathsync aio_readahead aio_fiemap aio_allocate
180	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
181	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
182	aio_chmod aio_utime aio_truncate	185	aio_chmod aio_utime aio_truncate
183	aio_msync aio_mtouch aio_mlock aio_mlockall	186	aio_msync aio_mtouch aio_mlock aio_mlockall
184	aio_statvfs	187	aio_statvfs
		188	aio_slurp
185	aio_wd);	189	aio_wd);
186		190
187	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	191	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
188	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	192	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
189	min_parallel max_parallel max_idle idle_timeout	193	min_parallel max_parallel max_idle idle_timeout
190	nreqs nready npending nthreads	194	nreqs nready npending nthreads
191	max_poll_time max_poll_reqs	195	max_poll_time max_poll_reqs
192	sendfile fadvise madvise	196	sendfile fadvise madvise
193	mmap munmap munlock munlockall);	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);
194		203
195	push @AIO_REQ, qw(aio_busy); # not exported	204	push @AIO_REQ, qw(aio_busy); # not exported
196		205
197	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	206	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
198		207
…		…
202		211
203	=head1 FUNCTIONS	212	=head1 FUNCTIONS
204		213
205	=head2 QUICK OVERVIEW	214	=head2 QUICK OVERVIEW
206		215
207	This section simply lists the prototypes of the most important functions	216	This section simply lists the prototypes most of the functions for
208	for quick reference. See the following sections for function-by-function	217	quick reference. See the following sections for function-by-function
209	documentation.	218	documentation.
210		219
211	aio_wd $pathname, $callback->($wd)	220	aio_wd $pathname, $callback->($wd)
212	aio_open $pathname, $flags, $mode, $callback->($fh)	221	aio_open $pathname, $flags, $mode, $callback->($fh)
213	aio_close $fh, $callback->($status)	222	aio_close $fh, $callback->($status)
		223	aio_seek $fh,$offset,$whence, $callback->($offs)
214	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	224	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
215	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	225	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
216	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	226	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
217	aio_readahead $fh,$offset,$length, $callback->($retval)	227	aio_readahead $fh,$offset,$length, $callback->($retval)
218	aio_stat $fh_or_path, $callback->($status)	228	aio_stat $fh_or_path, $callback->($status)
219	aio_lstat $fh, $callback->($status)	229	aio_lstat $fh, $callback->($status)
220	aio_statvfs $fh_or_path, $callback->($statvfs)	230	aio_statvfs $fh_or_path, $callback->($statvfs)
221	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	231	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
222	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)
223	aio_truncate $fh_or_path, $offset, $callback->($status)	234	aio_truncate $fh_or_path, $offset, $callback->($status)
224	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)
225	aio_unlink $pathname, $callback->($status)	237	aio_unlink $pathname, $callback->($status)
226	aio_mknod $pathname, $mode, $dev, $callback->($status)	238	aio_mknod $pathname, $mode, $dev, $callback->($status)
227	aio_link $srcpath, $dstpath, $callback->($status)	239	aio_link $srcpath, $dstpath, $callback->($status)
228	aio_symlink $srcpath, $dstpath, $callback->($status)	240	aio_symlink $srcpath, $dstpath, $callback->($status)
229	aio_readlink $pathname, $callback->($link)	241	aio_readlink $pathname, $callback->($link)
230	aio_realpath $pathname, $callback->($link)	242	aio_realpath $pathname, $callback->($path)
231	aio_rename $srcpath, $dstpath, $callback->($status)	243	aio_rename $srcpath, $dstpath, $callback->($status)
		244	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
232	aio_mkdir $pathname, $mode, $callback->($status)	245	aio_mkdir $pathname, $mode, $callback->($status)
233	aio_rmdir $pathname, $callback->($status)	246	aio_rmdir $pathname, $callback->($status)
234	aio_readdir $pathname, $callback->($entries)	247	aio_readdir $pathname, $callback->($entries)
235	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	248	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
236	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	249	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
237	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)
238	aio_load $pathname, $data, $callback->($status)	252	aio_load $pathname, $data, $callback->($status)
239	aio_copy $srcpath, $dstpath, $callback->($status)	253	aio_copy $srcpath, $dstpath, $callback->($status)
240	aio_move $srcpath, $dstpath, $callback->($status)	254	aio_move $srcpath, $dstpath, $callback->($status)
241	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
242	aio_rmtree $pathname, $callback->($status)	255	aio_rmtree $pathname, $callback->($status)
		256	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		257	aio_ioctl $fh, $request, $buf, $callback->($status)
243	aio_sync $callback->($status)	258	aio_sync $callback->($status)
244	aio_syncfs $fh, $callback->($status)	259	aio_syncfs $fh, $callback->($status)
245	aio_fsync $fh, $callback->($status)	260	aio_fsync $fh, $callback->($status)
246	aio_fdatasync $fh, $callback->($status)	261	aio_fdatasync $fh, $callback->($status)
247	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	262	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
248	aio_pathsync $pathname, $callback->($status)	263	aio_pathsync $pathname, $callback->($status)
249	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	264	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
250	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	265	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
251	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	266	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
252	aio_mlockall $flags, $callback->($status)	267	aio_mlockall $flags, $callback->($status)
253	aio_group $callback->(...)	268	aio_group $callback->(...)
254	aio_nop $callback->()	269	aio_nop $callback->()
…		…
268	IO::AIO::idle_timeout $seconds	283	IO::AIO::idle_timeout $seconds
269	IO::AIO::max_outstanding $maxreqs	284	IO::AIO::max_outstanding $maxreqs
270	IO::AIO::nreqs	285	IO::AIO::nreqs
271	IO::AIO::nready	286	IO::AIO::nready
272	IO::AIO::npending	287	IO::AIO::npending
		288	IO::AIO::reinit
		289
		290	$nfd = IO::AIO::get_fdlimit
		291	IO::AIO::min_fdlimit $nfd
273		292
274	IO::AIO::sendfile $ofh, $ifh, $offset, $count	293	IO::AIO::sendfile $ofh, $ifh, $offset, $count
275	IO::AIO::fadvise $fh, $offset, $len, $advice	294	IO::AIO::fadvise $fh, $offset, $len, $advice
		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]
276	IO::AIO::madvise $scalar, $offset, $length, $advice	300	IO::AIO::madvise $scalar, $offset, $length, $advice
277	IO::AIO::mprotect $scalar, $offset, $length, $protect	301	IO::AIO::mprotect $scalar, $offset, $length, $protect
278	IO::AIO::munlock $scalar, $offset = 0, $length = undef	302	IO::AIO::munlock $scalar, $offset = 0, $length = undef
279	IO::AIO::munlockall	303	IO::AIO::munlockall
280		304
281	=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, $flags = 0
		334
		335	=head2 API NOTES
282		336
283	All the C<aio_*> calls are more or less thin wrappers around the syscall	337	All the C<aio_*> calls are more or less thin wrappers around the syscall
284	with the same name (sans C<aio_>). The arguments are similar or identical,	338	with the same name (sans C<aio_>). The arguments are similar or identical,
285	and they all accept an additional (and optional) C<$callback> argument	339	and they all accept an additional (and optional) C<$callback> argument
286	which must be a code reference. This code reference will be called after	340	which must be a code reference. This code reference will be called after
…		…
317	correct contents.	371	correct contents.
318		372
319	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
320	handles correctly whether it is set or not.	374	handles correctly whether it is set or not.
321		375
		376	=head2 AIO REQUEST FUNCTIONS
		377
322	=over 4	378	=over 4
323		379
324	=item $prev_pri = aioreq_pri [$pri]	380	=item $prev_pri = aioreq_pri [$pri]
325		381
326	Returns the priority value that would be used for the next request and, if	382	Returns the priority value that would be used for the next request and, if
…		…
355		411
356		412
357	=item aio_open $pathname, $flags, $mode, $callback->($fh)	413	=item aio_open $pathname, $flags, $mode, $callback->($fh)
358		414
359	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
360	created filehandle for the file.	416	created filehandle for the file (or C<undef> in case of an error).
361
362	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
363	for an explanation.
364		417
365	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
366	list. They are the same as used by C<sysopen>.	419	list. They are the same as used by C<sysopen>.
367		420
368	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
…		…
388	following POSIX and non-POSIX constants are available (missing ones on	441	following POSIX and non-POSIX constants are available (missing ones on
389	your system are, as usual, C<0>):	442	your system are, as usual, C<0>):
390		443
391	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,	444	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
392	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,	445	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
393	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.	446	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
394		447
395		448
396	=item aio_close $fh, $callback->($status)	449	=item aio_close $fh, $callback->($status)
397		450
398	Asynchronously close a file and call the callback with the result	451	Asynchronously close a file and call the callback with the result
…		…
408	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
409	free for reuse until the perl filehandle is closed.	462	free for reuse until the perl filehandle is closed.
410		463
411	=cut	464	=cut
412		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
413	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	486	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
414		487
415	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	488	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
416		489
417	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
418	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
419	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
420	error, just like the syscall).	493	error, just like the syscall).
421		494
422	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
423	offset plus the actual number of bytes read.	496	offset plus the actual number of bytes read.
424		497
…		…
482	As native sendfile syscalls (as practically any non-POSIX interface hacked	555	As native sendfile syscalls (as practically any non-POSIX interface hacked
483	together in a hurry to improve benchmark numbers) tend to be rather buggy	556	together in a hurry to improve benchmark numbers) tend to be rather buggy
484	on many systems, this implementation tries to work around some known bugs	557	on many systems, this implementation tries to work around some known bugs
485	in Linux and FreeBSD kernels (probably others, too), but that might fail,	558	in Linux and FreeBSD kernels (probably others, too), but that might fail,
486	so you really really should check the return value of C<aio_sendfile> -	559	so you really really should check the return value of C<aio_sendfile> -
487	fewre bytes than expected might have been transferred.	560	fewer bytes than expected might have been transferred.
488		561
489		562
490	=item aio_readahead $fh,$offset,$length, $callback->($retval)	563	=item aio_readahead $fh,$offset,$length, $callback->($retval)
491		564
492	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
…		…
496	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
497	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
498	(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
499	file. The current file offset of the file is left unchanged.	572	file. The current file offset of the file is left unchanged.
500		573
501	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
502	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.
503		576
504		577
505	=item aio_stat $fh_or_path, $callback->($status)	578	=item aio_stat $fh_or_path, $callback->($status)
506		579
507	=item aio_lstat $fh, $callback->($status)	580	=item aio_lstat $fh, $callback->($status)
508		581
509	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
510	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
511	or C<-s _> etc...	584	using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
512		585	and C<-T>).
513	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
514	for an explanation.
515		586
516	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
517	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
518	unless perl itself is compiled with large file support.	589	unless perl itself is compiled with large file support.
519		590
…		…
523	behaviour).	594	behaviour).
524		595
525	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,	596	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
526	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,	597	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
527	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.	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>.
528		602
529	Example: Print the length of F</etc/passwd>:	603	Example: Print the length of F</etc/passwd>:
530		604
531	aio_stat "/etc/passwd", sub {	605	aio_stat "/etc/passwd", sub {
532	$_[0] and die "stat failed: $!";	606	$_[0] and die "stat failed: $!";
…		…
576	namemax => 255,	650	namemax => 255,
577	frsize => 1024,	651	frsize => 1024,
578	fsid => 1810	652	fsid => 1810
579	}	653	}
580		654
581
582	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	655	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
583		656
584	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
585	and $mtime being undef). Fractional times are supported if the underlying	658	and $mtime being undef). Fractional times are supported if the underlying
586	syscalls support them.	659	syscalls support them.
587		660
588	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,
589	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)
590	otherwise returns ENOSYS, so this is not portable.	663	or futimes(2) if available, otherwise returns ENOSYS, so this is not
		664	portable.
591		665
592	Examples:	666	Examples:
593		667
594	# set atime and mtime to current time (basically touch(1)):	668	# set atime and mtime to current time (basically touch(1)):
595	aio_utime "path", undef, undef;	669	aio_utime "path", undef, undef;
…		…
613	=item aio_truncate $fh_or_path, $offset, $callback->($status)	687	=item aio_truncate $fh_or_path, $offset, $callback->($status)
614		688
615	Works like truncate(2) or ftruncate(2).	689	Works like truncate(2) or ftruncate(2).
616		690
617		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
618	=item aio_chmod $fh_or_path, $mode, $callback->($status)	714	=item aio_chmod $fh_or_path, $mode, $callback->($status)
619		715
620	Works like perl's C<chmod> function.	716	Works like perl's C<chmod> function.
621		717
622		718
…		…
659		755
660		756
661	=item aio_realpath $pathname, $callback->($path)	757	=item aio_realpath $pathname, $callback->($path)
662		758
663	Asynchronously make the path absolute and resolve any symlinks in	759	Asynchronously make the path absolute and resolve any symlinks in
664	C<$path>. The resulting path only consists of directories (Same as	760	C<$path>. The resulting path only consists of directories (same as
665	L<Cwd::realpath>).	761	L<Cwd::realpath>).
666		762
667	This request can be used to get the absolute path of the current working	763	This request can be used to get the absolute path of the current working
668	directory by passing it a path of F<.> (a single dot).	764	directory by passing it a path of F<.> (a single dot).
669		765
670		766
671	=item aio_rename $srcpath, $dstpath, $callback->($status)	767	=item aio_rename $srcpath, $dstpath, $callback->($status)
672		768
673	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
674	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>.
675		791
676		792
677	=item aio_mkdir $pathname, $mode, $callback->($status)	793	=item aio_mkdir $pathname, $mode, $callback->($status)
678		794
679	Asynchronously mkdir (create) a directory and call the callback with	795	Asynchronously mkdir (create) a directory and call the callback with
…		…
684	=item aio_rmdir $pathname, $callback->($status)	800	=item aio_rmdir $pathname, $callback->($status)
685		801
686	Asynchronously rmdir (delete) a directory and call the callback with the	802	Asynchronously rmdir (delete) a directory and call the callback with the
687	result code.	803	result code.
688		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
689		809
690	=item aio_readdir $pathname, $callback->($entries)	810	=item aio_readdir $pathname, $callback->($entries)
691		811
692	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
693	directory (i.e. opendir + readdir + closedir). The entries will not be	813	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
708		828
709	=over 4	829	=over 4
710		830
711	=item IO::AIO::READDIR_DENTS	831	=item IO::AIO::READDIR_DENTS
712		832
713	When this flag is off, then the callback gets an arrayref consisting of	833	Normally the callback gets an arrayref consisting of names only (as
714	names 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
715	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	835	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
716	entry in more detail.	836	single directory entry in more detail:
717		837
718	C<$name> is the name of the entry.	838	C<$name> is the name of the entry.
719		839
720	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	840	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
721		841
722	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	842	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
723	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	843	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
724	C<IO::AIO::DT_WHT>.	844	C<IO::AIO::DT_WHT>.
725		845
726	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	846	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
727	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	847	to know, you have to run stat yourself. Also, for speed/memory reasons,
728	scalars are read-only: you can not modify them.	848	the C<$type> scalars are read-only: you must not modify them.
729		849
730	C<$inode> is the inode number (which might not be exact on systems with 64	850	C<$inode> is the inode number (which might not be exact on systems with 64
731	bit inode numbers and 32 bit perls). This field has unspecified content on	851	bit inode numbers and 32 bit perls). This field has unspecified content on
732	systems that do not deliver the inode information.	852	systems that do not deliver the inode information.
733		853
…		…
744	short names are tried first.	864	short names are tried first.
745		865
746	=item IO::AIO::READDIR_STAT_ORDER	866	=item IO::AIO::READDIR_STAT_ORDER
747		867
748	When this flag is set, then the names will be returned in an order	868	When this flag is set, then the names will be returned in an order
749	suitable for stat()'ing each one. That is, when you plan to stat()	869	suitable for stat()'ing each one. That is, when you plan to stat() most or
750	all files in the given directory, then the returned order will likely	870	all files in the given directory, then the returned order will likely be
751	be fastest.	871	faster.
752		872
753	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then	873	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
754	the likely dirs come first, resulting in a less optimal stat order.	874	then the likely dirs come first, resulting in a less optimal stat order
		875	for stat'ing all entries, but likely a more optimal order for finding
		876	subdirectories.
755		877
756	=item IO::AIO::READDIR_FOUND_UNKNOWN	878	=item IO::AIO::READDIR_FOUND_UNKNOWN
757		879
758	This flag should not be set when calling C<aio_readdirx>. Instead, it	880	This flag should not be set when calling C<aio_readdirx>. Instead, it
759	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	881	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
…		…
761	C<$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.
762		884
763	=back	885	=back
764		886
765		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
766	=item aio_load $pathname, $data, $callback->($status)	917	=item aio_load $pathname, $data, $callback->($status)
767		918
768	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
769	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.
770		923
771	=cut	924	=cut
772		925
773	sub aio_load($$;$) {	926	sub aio_load($$;$) {
774	my ($path, undef, $cb) = @_;	927	my ($path, undef, $cb) = @_;
…		…
795		948
796	Try to copy the I<file> (directories not supported as either source or	949	Try to copy the I<file> (directories not supported as either source or
797	destination) from C<$srcpath> to C<$dstpath> and call the callback with	950	destination) from C<$srcpath> to C<$dstpath> and call the callback with
798	a status of C<0> (ok) or C<-1> (error, see C<$!>).	951	a status of C<0> (ok) or C<-1> (error, see C<$!>).
799		952
		953	Existing destination files will be truncated.
		954
800	This is a composite request that creates the destination file with	955	This is a composite request that creates the destination file with
801	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
802	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	957	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
803	uid/gid, in that order.	958	uid/gid, in that order.
804		959
…		…
820	my @stat = stat $src_fh; # hmm, might block over nfs?	975	my @stat = stat $src_fh; # hmm, might block over nfs?
821		976
822	aioreq_pri $pri;	977	aioreq_pri $pri;
823	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	978	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
824	if (my $dst_fh = $_[0]) {	979	if (my $dst_fh = $_[0]) {
		980
		981	# best-effort preallocate
		982	aioreq_pri $pri;
		983	add $grp aio_allocate $dst_fh, IO::AIO::FALLOC_FL_KEEP_SIZE, 0, $stat[7], sub { };
		984
825	aioreq_pri $pri;	985	aioreq_pri $pri;
826	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	986	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
827	if ($_[0] == $stat[7]) {	987	if ($_[0] == $stat[7]) {
828	$grp->result (0);	988	$grp->result (0);
829	close $src_fh;	989	close $src_fh;
…		…
913	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1073	Scans a directory (similar to C<aio_readdir>) but additionally tries to
914	efficiently separate the entries of directory C<$path> into two sets of	1074	efficiently separate the entries of directory C<$path> into two sets of
915	names, directories you can recurse into (directories), and ones you cannot	1075	names, directories you can recurse into (directories), and ones you cannot
916	recurse into (everything else, including symlinks to directories).	1076	recurse into (everything else, including symlinks to directories).
917		1077
918	C<aio_scandir> is a composite request that creates of many sub requests_	1078	C<aio_scandir> is a composite request that generates many sub requests.
919	C<$maxreq> specifies the maximum number of outstanding aio requests that	1079	C<$maxreq> specifies the maximum number of outstanding aio requests that
920	this function generates. If it is C<< <= 0 >>, then a suitable default	1080	this function generates. If it is C<< <= 0 >>, then a suitable default
921	will be chosen (currently 4).	1081	will be chosen (currently 4).
922		1082
923	On error, the callback is called without arguments, otherwise it receives	1083	On error, the callback is called without arguments, otherwise it receives
…		…
987	aioreq_pri $pri;	1147	aioreq_pri $pri;
988	add $grp aio_stat $wd, sub {	1148	add $grp aio_stat $wd, sub {
989	return $grp->result () if $_[0];	1149	return $grp->result () if $_[0];
990	my $now = time;	1150	my $now = time;
991	my $hash1 = join ":", (stat _)[0,1,3,7,9];	1151	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		1152	my $rdxflags = READDIR_DIRS_FIRST;
		1153
		1154	if ((stat _)[3] < 2) {
		1155	# at least one non-POSIX filesystem exists
		1156	# that returns useful DT_type values: btrfs,
		1157	# so optimise for this here by requesting dents
		1158	$rdxflags |= READDIR_DENTS;
		1159	}
992		1160
993	# read the directory entries	1161	# read the directory entries
994	aioreq_pri $pri;	1162	aioreq_pri $pri;
995	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {	1163	add $grp aio_readdirx $wd, $rdxflags, sub {
996	my $entries = shift	1164	my ($entries, $flags) = @_
997	or return $grp->result ();	1165	or return $grp->result ();
		1166
		1167	if ($rdxflags & READDIR_DENTS) {
		1168	# if we requested type values, see if we can use them directly.
		1169
		1170	# if there were any DT_UNKNOWN entries then we assume we
		1171	# don't know. alternatively, we could assume that if we get
		1172	# one DT_DIR, then all directories are indeed marked with
		1173	# DT_DIR, but this seems not required for btrfs, and this
		1174	# is basically the "btrfs can't get it's act together" code
		1175	# branch.
		1176	unless ($flags & READDIR_FOUND_UNKNOWN) {
		1177	# now we have valid DT_ information for all entries,
		1178	# so use it as an optimisation without further stat's.
		1179	# they must also all be at the beginning of @$entries
		1180	# by now.
		1181
		1182	my $dirs;
		1183
		1184	if (@$entries) {
		1185	for (0 .. $#$entries) {
		1186	if ($entries->[$_][1] != DT_DIR) {
		1187	# splice out directories
		1188	$dirs = [splice @$entries, 0, $_];
		1189	last;
		1190	}
		1191	}
		1192
		1193	# if we didn't find any non-dir, then all entries are dirs
		1194	unless ($dirs) {
		1195	($dirs, $entries) = ($entries, []);
		1196	}
		1197	} else {
		1198	# directory is empty, so there are no sbdirs
		1199	$dirs = [];
		1200	}
		1201
		1202	# either splice'd the directories out or the dir was empty.
		1203	# convert dents to filenames
		1204	$_ = $_->[0] for @$dirs;
		1205	$_ = $_->[0] for @$entries;
		1206
		1207	return $grp->result ($dirs, $entries);
		1208	}
		1209
		1210	# cannot use, so return to our old ways
		1211	# by pretending we only scanned for names.
		1212	$_ = $_->[0] for @$entries;
		1213	}
998		1214
999	# stat the dir another time	1215	# stat the dir another time
1000	aioreq_pri $pri;	1216	aioreq_pri $pri;
1001	add $grp aio_stat $wd, sub {	1217	add $grp aio_stat $wd, sub {
1002	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1218	my $hash2 = join ":", (stat _)[0,1,3,7,9];
…		…
1057	}	1273	}
1058		1274
1059	=item aio_rmtree $pathname, $callback->($status)	1275	=item aio_rmtree $pathname, $callback->($status)
1060		1276
1061	Delete a directory tree starting (and including) C<$path>, return the	1277	Delete a directory tree starting (and including) C<$path>, return the
1062	status of the final C<rmdir> only. This is a composite request that	1278	status of the final C<rmdir> only. This is a composite request that
1063	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1279	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1064	everything else.	1280	everything else.
1065		1281
1066	=cut	1282	=cut
1067		1283
…		…
1088	add $grp $dirgrp;	1304	add $grp $dirgrp;
1089	};	1305	};
1090		1306
1091	$grp	1307	$grp
1092	}	1308	}
		1309
		1310	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1311
		1312	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1313
		1314	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1315	they execute asynchronously and pass the return value to the callback.
		1316
		1317	Both calls can be used for a lot of things, some of which make more sense
		1318	to run asynchronously in their own thread, while some others make less
		1319	sense. For example, calls that block waiting for external events, such
		1320	as locking, will also lock down an I/O thread while it is waiting, which
		1321	can deadlock the whole I/O system. At the same time, there might be no
		1322	alternative to using a thread to wait.
		1323
		1324	So in general, you should only use these calls for things that do
		1325	(filesystem) I/O, not for things that wait for other events (network,
		1326	other processes), although if you are careful and know what you are doing,
		1327	you still can.
		1328
		1329	The following constants are available and can be used for normal C<ioctl>
		1330	and C<fcntl> as well (missing ones are, as usual C<0>):
		1331
		1332	C<F_DUPFD_CLOEXEC>,
		1333
		1334	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1335
		1336	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1337
		1338	C<F_ADD_SEALS>, C<F_GET_SEALS>, C<F_SEAL_SEAL>, C<F_SEAL_SHRINK>, C<F_SEAL_GROW> and
		1339	C<F_SEAL_WRITE>.
		1340
		1341	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1342	C<FS_IOC_FIEMAP>.
		1343
		1344	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1345	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1346
		1347	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1348	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1349	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1350	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1351	C<FS_FL_USER_MODIFIABLE>.
		1352
		1353	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1354	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1355	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1356	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1357
		1358	C<BLKROSET>, C<BLKROGET>, C<BLKRRPART>, C<BLKGETSIZE>, C<BLKFLSBUF>, C<BLKRASET>,
		1359	C<BLKRAGET>, C<BLKFRASET>, C<BLKFRAGET>, C<BLKSECTSET>, C<BLKSECTGET>, C<BLKSSZGET>,
		1360	C<BLKBSZGET>, C<BLKBSZSET>, C<BLKGETSIZE64>,
		1361
1093		1362
1094	=item aio_sync $callback->($status)	1363	=item aio_sync $callback->($status)
1095		1364
1096	Asynchronously call sync and call the callback when finished.	1365	Asynchronously call sync and call the callback when finished.
1097		1366
…		…
1166	};	1435	};
1167		1436
1168	$grp	1437	$grp
1169	}	1438	}
1170		1439
1171	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1440	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1172		1441
1173	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1442	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1174	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1443	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1175	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1444	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1176	scalar must only be modified in-place while an aio operation is pending on	1445	scalar must only be modified in-place while an aio operation is pending on
…		…
1178		1447
1179	It calls the C<msync> function of your OS, if available, with the memory	1448	It calls the C<msync> function of your OS, if available, with the memory
1180	area starting at C<$offset> in the string and ending C<$length> bytes	1449	area starting at C<$offset> in the string and ending C<$length> bytes
1181	later. If C<$length> is negative, counts from the end, and if C<$length>	1450	later. If C<$length> is negative, counts from the end, and if C<$length>
1182	is C<undef>, then it goes till the end of the string. The flags can be	1451	is C<undef>, then it goes till the end of the string. The flags can be
1183	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1452	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1184	C<IO::AIO::MS_SYNC>.	1453	C<IO::AIO::MS_INVALIDATE>.
1185		1454
1186	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1455	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1187		1456
1188	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1457	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1189	scalars.	1458	scalars.
1190		1459
1191	It touches (reads or writes) all memory pages in the specified	1460	It touches (reads or writes) all memory pages in the specified
1192	range inside the scalar. All caveats and parameters are the same	1461	range inside the scalar. All caveats and parameters are the same
1193	as for C<aio_msync>, above, except for flags, which must be either	1462	as for C<aio_msync>, above, except for flags, which must be either
1194	C<0> (which reads all pages and ensures they are instantiated) or	1463	C<0> (which reads all pages and ensures they are instantiated) or
1195	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1464	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1196	writing an octet from it, which dirties the page).	1465	writing an octet from it, which dirties the page).
1197		1466
1198	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1467	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1199		1468
1200	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1469	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1219	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;	1488	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1220	aio_mlock $data; # mlock in background	1489	aio_mlock $data; # mlock in background
1221		1490
1222	=item aio_mlockall $flags, $callback->($status)	1491	=item aio_mlockall $flags, $callback->($status)
1223		1492
1224	Calls the C<mlockall> function with the given C<$flags> (a combination of	1493	Calls the C<mlockall> function with the given C<$flags> (a
1225	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).	1494	combination of C<IO::AIO::MCL_CURRENT>, C<IO::AIO::MCL_FUTURE> and
		1495	C<IO::AIO::MCL_ONFAULT>).
1226		1496
1227	On systems that do not implement C<mlockall>, this function returns C<-1>	1497	On systems that do not implement C<mlockall>, this function returns C<-1>
1228	and sets errno to C<ENOSYS>.	1498	and sets errno to C<ENOSYS>. Similarly, flag combinations not supported
		1499	by the system result in a return value of C<-1> with errno being set to
		1500	C<EINVAL>.
1229		1501
1230	Note that the corresponding C<munlockall> is synchronous and is	1502	Note that the corresponding C<munlockall> is synchronous and is
1231	documented under L<MISCELLANEOUS FUNCTIONS>.	1503	documented under L<MISCELLANEOUS FUNCTIONS>.
1232		1504
1233	Example: asynchronously lock all current and future pages into memory.	1505	Example: asynchronously lock all current and future pages into memory.
1234		1506
1235	aio_mlockall IO::AIO::MCL_FUTURE;	1507	aio_mlockall IO::AIO::MCL_FUTURE;
		1508
		1509	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1510
		1511	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1512	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1513	the ioctl is not available on your OS, then this request will fail with
		1514	C<ENOSYS>.
		1515
		1516	C<$start> is the starting offset to query extents for, C<$length> is the
		1517	size of the range to query - if it is C<undef>, then the whole file will
		1518	be queried.
		1519
		1520	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1521	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1522	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1523	the data portion.
		1524
		1525	C<$count> is the maximum number of extent records to return. If it is
		1526	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1527	case, if it is C<0>, then the callback receives the number of extents
		1528	instead of the extents themselves (which is unreliable, see below).
		1529
		1530	If an error occurs, the callback receives no arguments. The special
		1531	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1532
		1533	Otherwise, the callback receives an array reference with extent
		1534	structures. Each extent structure is an array reference itself, with the
		1535	following members:
		1536
		1537	[$logical, $physical, $length, $flags]
		1538
		1539	Flags is any combination of the following flag values (typically either C<0>
		1540	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1541
		1542	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1543	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1544	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1545	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1546	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1547	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1548
		1549	At the time of this writing (Linux 3.2), this request is unreliable unless
		1550	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1551	it to return all extents of a range for files with a large number of
		1552	extents. The code (only) works around all these issues if C<$count> is
		1553	C<undef>.
1236		1554
1237	=item aio_group $callback->(...)	1555	=item aio_group $callback->(...)
1238		1556
1239	This is a very special aio request: Instead of doing something, it is a	1557	This is a very special aio request: Instead of doing something, it is a
1240	container for other aio requests, which is useful if you want to bundle	1558	container for other aio requests, which is useful if you want to bundle
…		…
1304	object. This object stores the canonicalised, absolute version of the	1622	object. This object stores the canonicalised, absolute version of the
1305	path, and on systems that allow it, also a directory file descriptor.	1623	path, and on systems that allow it, also a directory file descriptor.
1306		1624
1307	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>	1625	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1308	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD	1626	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1309	object and a pathname instead. If the pathname is absolute, the	1627	object and a pathname instead (or the IO::AIO::WD object alone, which
		1628	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1310	IO::AIO::WD objetc is ignored, otherwise the pathname is resolved relative	1629	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1311	to that IO::AIO::WD object.	1630	to that IO::AIO::WD object.
1312		1631
1313	For example, to get a wd object for F</etc> and then stat F<passwd>	1632	For example, to get a wd object for F</etc> and then stat F<passwd>
1314	inside, you would write:	1633	inside, you would write:
1315		1634
…		…
1323	aio_stat [$etcdir, "passwd"], sub {	1642	aio_stat [$etcdir, "passwd"], sub {
1324	# yay	1643	# yay
1325	};	1644	};
1326	};	1645	};
1327		1646
		1647	The fact that C<aio_wd> is a request and not a normal function shows that
1328	This shows that creating an IO::AIO::WD object is itself a potentially	1648	creating an IO::AIO::WD object is itself a potentially blocking operation,
1329	blocking operation, which is why it is done asynchronously.	1649	which is why it is done asynchronously.
		1650
		1651	To stat the directory obtained with C<aio_wd> above, one could write
		1652	either of the following three request calls:
		1653
		1654	aio_lstat "/etc" , sub { ... # pathname as normal string
		1655	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1656	aio_lstat $wd , sub { ... # shorthand for the previous
1330		1657
1331	As with normal pathnames, IO::AIO keeps a copy of the working directory	1658	As with normal pathnames, IO::AIO keeps a copy of the working directory
1332	object and the pathname string, so you could write the following without	1659	object and the pathname string, so you could write the following without
1333	causing any issues due to C<$path> getting reused:	1660	causing any issues due to C<$path> getting reused:
1334		1661
…		…
1344	There are some caveats: when directories get renamed (or deleted), the	1671	There are some caveats: when directories get renamed (or deleted), the
1345	pathname string doesn't change, so will point to the new directory (or	1672	pathname string doesn't change, so will point to the new directory (or
1346	nowhere at all), while the directory fd, if available on the system,	1673	nowhere at all), while the directory fd, if available on the system,
1347	will still point to the original directory. Most functions accepting a	1674	will still point to the original directory. Most functions accepting a
1348	pathname will use the directory fd on newer systems, and the string on	1675	pathname will use the directory fd on newer systems, and the string on
1349	older systems. Some functions (such as realpath) will always rely on the	1676	older systems. Some functions (such as C<aio_realpath>) will always rely on
1350	string form of the pathname.	1677	the string form of the pathname.
1351		1678
1352	So this fucntionality is mainly useful to get some protection against	1679	So this functionality is mainly useful to get some protection against
1353	C<chdir>, to easily get an absolute path out of a relative path for future	1680	C<chdir>, to easily get an absolute path out of a relative path for future
1354	reference, and to speed up doing many operations in the same directory	1681	reference, and to speed up doing many operations in the same directory
1355	(e.g. when stat'ing all files in a directory).	1682	(e.g. when stat'ing all files in a directory).
1356		1683
1357	The following functions implement this working directory abstraction:	1684	The following functions implement this working directory abstraction:
…		…
1370	passing C<undef> as working directory component of a pathname fails the	1697	passing C<undef> as working directory component of a pathname fails the
1371	request with C<ENOENT>, there is often no need for error checking in the	1698	request with C<ENOENT>, there is often no need for error checking in the
1372	C<aio_wd> callback, as future requests using the value will fail in the	1699	C<aio_wd> callback, as future requests using the value will fail in the
1373	expected way.	1700	expected way.
1374		1701
1375	If this call isn't available because your OS lacks it or it couldn't be
1376	detected, it will be emulated by calling C<fsync> instead.
1377
1378	=item IO::AIO::CWD	1702	=item IO::AIO::CWD
1379		1703
1380	This is a compiletime constant (object) that represents the process	1704	This is a compile time constant (object) that represents the process
1381	current working directory.	1705	current working directory.
1382		1706
1383	Specifying this object as working directory object for a pathname is as	1707	Specifying this object as working directory object for a pathname is as if
1384	if the pathname would be specified directly, without a directory object,	1708	the pathname would be specified directly, without a directory object. For
1385	e.g., these calls are functionally identical:	1709	example, these calls are functionally identical:
1386		1710
1387	aio_stat "somefile", sub { ... };	1711	aio_stat "somefile", sub { ... };
1388	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };	1712	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1389		1713
1390	=back	1714	=back
1391		1715
		1716	To recover the path associated with an IO::AIO::WD object, you can use
		1717	C<aio_realpath>:
		1718
		1719	aio_realpath $wd, sub {
		1720	warn "path is $_[0]\n";
		1721	};
		1722
		1723	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1724	sometimes, fall back to using an absolue path.
1392		1725
1393	=head2 IO::AIO::REQ CLASS	1726	=head2 IO::AIO::REQ CLASS
1394		1727
1395	All non-aggregate C<aio_*> functions return an object of this class when	1728	All non-aggregate C<aio_*> functions return an object of this class when
1396	called in non-void context.	1729	called in non-void context.
…		…
1557	The default value for the limit is C<0>, but note that setting a feeder	1890	The default value for the limit is C<0>, but note that setting a feeder
1558	automatically bumps it up to C<2>.	1891	automatically bumps it up to C<2>.
1559		1892
1560	=back	1893	=back
1561		1894
		1895
1562	=head2 SUPPORT FUNCTIONS	1896	=head2 SUPPORT FUNCTIONS
1563		1897
1564	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1898	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1565		1899
1566	=over 4	1900	=over 4
…		…
1574		1908
1575	See C<poll_cb> for an example.	1909	See C<poll_cb> for an example.
1576		1910
1577	=item IO::AIO::poll_cb	1911	=item IO::AIO::poll_cb
1578		1912
1579	Process some outstanding events on the result pipe. You have to call	1913	Process some requests that have reached the result phase (i.e. they have
		1914	been executed but the results are not yet reported). You have to call
		1915	this "regularly" to finish outstanding requests.
		1916
1580	this regularly. Returns C<0> if all events could be processed (or there	1917	Returns C<0> if all events could be processed (or there were no
1581	were no events to process), or C<-1> if it returned earlier for whatever	1918	events to process), or C<-1> if it returned earlier for whatever
1582	reason. Returns immediately when no events are outstanding. The amount of	1919	reason. Returns immediately when no events are outstanding. The amount
1583	events processed depends on the settings of C<IO::AIO::max_poll_req> and	1920	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1584	C<IO::AIO::max_poll_time>.	1921	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1585		1922
1586	If not all requests were processed for whatever reason, the filehandle	1923	If not all requests were processed for whatever reason, the poll file
1587	will still be ready when C<poll_cb> returns, so normally you don't have to	1924	descriptor will still be ready when C<poll_cb> returns, so normally you
1588	do anything special to have it called later.	1925	don't have to do anything special to have it called later.
1589		1926
1590	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1927	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1591	ready, it can be beneficial to call this function from loops which submit	1928	ready, it can be beneficial to call this function from loops which submit
1592	a lot of requests, to make sure the results get processed when they become	1929	a lot of requests, to make sure the results get processed when they become
1593	available and not just when the loop is finished and the event loop takes	1930	available and not just when the loop is finished and the event loop takes
…		…
1602	poll => 'r', async => 1,	1939	poll => 'r', async => 1,
1603	cb => \&IO::AIO::poll_cb);	1940	cb => \&IO::AIO::poll_cb);
1604		1941
1605	=item IO::AIO::poll_wait	1942	=item IO::AIO::poll_wait
1606		1943
1607	If there are any outstanding requests and none of them in the result	1944	Wait until either at least one request is in the result phase or no
1608	phase, wait till the result filehandle becomes ready for reading (simply	1945	requests are outstanding anymore.
1609	does a C<select> on the filehandle. This is useful if you want to	1946
1610	synchronously wait for some requests to finish).	1947	This is useful if you want to synchronously wait for some requests to
		1948	become ready, without actually handling them.
1611		1949
1612	See C<nreqs> for an example.	1950	See C<nreqs> for an example.
1613		1951
1614	=item IO::AIO::poll	1952	=item IO::AIO::poll
1615		1953
…		…
1626		1964
1627	Strictly equivalent to:	1965	Strictly equivalent to:
1628		1966
1629	IO::AIO::poll_wait, IO::AIO::poll_cb	1967	IO::AIO::poll_wait, IO::AIO::poll_cb
1630	while IO::AIO::nreqs;	1968	while IO::AIO::nreqs;
		1969
		1970	This function can be useful at program aborts, to make sure outstanding
		1971	I/O has been done (C<IO::AIO> uses an C<END> block which already calls
		1972	this function on normal exits), or when you are merely using C<IO::AIO>
		1973	for its more advanced functions, rather than for async I/O, e.g.:
		1974
		1975	my ($dirs, $nondirs);
		1976	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1977	IO::AIO::flush;
		1978	# $dirs, $nondirs are now set
1631		1979
1632	=item IO::AIO::max_poll_reqs $nreqs	1980	=item IO::AIO::max_poll_reqs $nreqs
1633		1981
1634	=item IO::AIO::max_poll_time $seconds	1982	=item IO::AIO::max_poll_time $seconds
1635		1983
…		…
1662	poll => 'r', nice => 1,	2010	poll => 'r', nice => 1,
1663	cb => &IO::AIO::poll_cb);	2011	cb => &IO::AIO::poll_cb);
1664		2012
1665	=back	2013	=back
1666		2014
		2015
1667	=head3 CONTROLLING THE NUMBER OF THREADS	2016	=head3 CONTROLLING THE NUMBER OF THREADS
1668		2017
1669	=over	2018	=over
1670		2019
1671	=item IO::AIO::min_parallel $nthreads	2020	=item IO::AIO::min_parallel $nthreads
…		…
1732	longer exceeded.	2081	longer exceeded.
1733		2082
1734	In other words, this setting does not enforce a queue limit, but can be	2083	In other words, this setting does not enforce a queue limit, but can be
1735	used to make poll functions block if the limit is exceeded.	2084	used to make poll functions block if the limit is exceeded.
1736		2085
1737	This is a very bad function to use in interactive programs because it	2086	This is a bad function to use in interactive programs because it blocks,
1738	blocks, and a bad way to reduce concurrency because it is inexact: Better	2087	and a bad way to reduce concurrency because it is inexact. If you need to
		2088	issue many requests without being able to call a poll function on demand,
1739	use an C<aio_group> together with a feed callback.	2089	it is better to use an C<aio_group> together with a feed callback.
1740		2090
1741	It's main use is in scripts without an event loop - when you want to stat	2091	Its main use is in scripts without an event loop - when you want to stat a
1742	a lot of files, you can write somehting like this:	2092	lot of files, you can write something like this:
1743		2093
1744	IO::AIO::max_outstanding 32;	2094	IO::AIO::max_outstanding 32;
1745		2095
1746	for my $path (...) {	2096	for my $path (...) {
1747	aio_stat $path , ...;	2097	aio_stat $path , ...;
1748	IO::AIO::poll_cb;	2098	IO::AIO::poll_cb;
1749	}	2099	}
1750		2100
1751	IO::AIO::flush;	2101	IO::AIO::flush;
1752		2102
1753	The call to C<poll_cb> inside the loop will normally return instantly, but	2103	The call to C<poll_cb> inside the loop will normally return instantly,
1754	as soon as more thna C<32> reqeusts are in-flight, it will block until	2104	allowing the loop to progress, but as soon as more than C<32> requests
1755	some requests have been handled. This keeps the loop from pushing a large	2105	are in-flight, it will block until some requests have been handled. This
1756	number of C<aio_stat> requests onto the queue.	2106	keeps the loop from pushing a large number of C<aio_stat> requests onto
		2107	the queue (which, with many paths to stat, can use up a lot of memory).
1757		2108
1758	The default value for C<max_outstanding> is very large, so there is no	2109	The default value for C<max_outstanding> is very large, so there is no
1759	practical limit on the number of outstanding requests.	2110	practical limit on the number of outstanding requests.
1760		2111
1761	=back	2112	=back
1762		2113
		2114
1763	=head3 STATISTICAL INFORMATION	2115	=head3 STATISTICAL INFORMATION
1764		2116
1765	=over	2117	=over
1766		2118
1767	=item IO::AIO::nreqs	2119	=item IO::AIO::nreqs
…		…
1784	Returns the number of requests currently in the pending state (executed,	2136	Returns the number of requests currently in the pending state (executed,
1785	but not yet processed by poll_cb).	2137	but not yet processed by poll_cb).
1786		2138
1787	=back	2139	=back
1788		2140
		2141
		2142	=head3 SUBSECOND STAT TIME ACCESS
		2143
		2144	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2145	generally find access/modification and change times with subsecond time
		2146	accuracy of the system supports it, but perl's built-in functions only
		2147	return the integer part.
		2148
		2149	The following functions return the timestamps of the most recent
		2150	stat with subsecond precision on most systems and work both after
		2151	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2152	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2153	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2154
		2155	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2156	full resolution without rounding and work with standard perl C<stat>,
		2157	alleviating the need to call the special C<Time::HiRes> functions, which
		2158	do not act like their perl counterparts.
		2159
		2160	On operating systems or file systems where subsecond time resolution is
		2161	not supported or could not be detected, a fractional part of C<0> is
		2162	returned, so it is always safe to call these functions.
		2163
		2164	=over 4
		2165
		2166	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		2167
		2168	Return the access, modication, change or birth time, respectively,
		2169	including fractional part. Due to the limited precision of floating point,
		2170	the accuracy on most platforms is only a bit better than milliseconds
		2171	for times around now - see the I<nsec> function family, below, for full
		2172	accuracy.
		2173
		2174	File birth time is only available when the OS and perl support it (on
		2175	FreeBSD and NetBSD at the time of this writing, although support is
		2176	adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
		2177	it). On systems where it isn't available, C<0> is currently returned, but
		2178	this might change to C<undef> in a future version.
		2179
		2180	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		2181
		2182	Returns access, modification, change and birth time all in one go, and
		2183	maybe more times in the future version.
		2184
		2185	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		2186
		2187	Return the fractional access, modifcation, change or birth time, in nanoseconds,
		2188	as an integer in the range C<0> to C<999999999>.
		2189
		2190	Note that no accessors are provided for access, modification and
		2191	change times - you need to get those from C<stat _> if required (C<int
		2192	IO::AIO::st_atime> and so on will I<not> generally give you the correct
		2193	value).
		2194
		2195	=item $seconds = IO::AIO::st_btimesec
		2196
		2197	The (integral) seconds part of the file birth time, if available.
		2198
		2199	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		2200
		2201	Like the functions above, but returns all four times in one go (and maybe
		2202	more in future versions).
		2203
		2204	=item $counter = IO::AIO::st_gen
		2205
		2206	Returns the generation counter (in practice this is just a random number)
		2207	of the file. This is only available on platforms which have this member in
		2208	their C<struct stat> (most BSDs at the time of this writing) and generally
		2209	only to the root usert. If unsupported, C<0> is returned, but this might
		2210	change to C<undef> in a future version.
		2211
		2212	=back
		2213
		2214	Example: print the high resolution modification time of F</etc>, using
		2215	C<stat>, and C<IO::AIO::aio_stat>.
		2216
		2217	if (stat "/etc") {
		2218	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2219	}
		2220
		2221	IO::AIO::aio_stat "/etc", sub {
		2222	$_[0]
		2223	and return;
		2224
		2225	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2226	};
		2227
		2228	IO::AIO::flush;
		2229
		2230	Output of the awbove on my system, showing reduced and full accuracy:
		2231
		2232	stat(/etc) mtime: 1534043702.020808
		2233	aio_stat(/etc) mtime: 1534043702.020807792
		2234
		2235
1789	=head3 MISCELLANEOUS FUNCTIONS	2236	=head3 MISCELLANEOUS FUNCTIONS
1790		2237
1791	IO::AIO implements some functions that might be useful, but are not	2238	IO::AIO implements some functions that are useful when you want to use
1792	asynchronous.	2239	some "Advanced I/O" function not available to in Perl, without going the
		2240	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2241	counterpart.
1793		2242
1794	=over 4	2243	=over 4
		2244
		2245	=item $retval = IO::AIO::fexecve $fh, $argv, $envp
		2246
		2247	A more-or-less direct equivalent to the POSIX C<fexecve> functions, which
		2248	allows you to specify the program to be executed via a file descriptor (or
		2249	handle). Returns C<-1> and sets errno to C<ENOSYS> if not available.
		2250
		2251	=item $retval = IO::AIO::mount $special, $path, $fstype, $flags = 0, $data = undef
		2252
		2253	Calls the GNU/Linux mount syscall with the given arguments. All except
		2254	C<$flags> are strings, and if C<$data> is C<undef>, a C<NULL> will be
		2255	passed.
		2256
		2257	The following values for C<$flags> are available:
		2258
		2259	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>,
		2260	C<IO::AIO::MS_REMOUNT>, C<IO::AIO::MS_MANDLOCK>, C<IO::AIO::MS_DIRSYNC>, C<IO::AIO::MS_NOATIME>,
		2261	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>,
		2262	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>,
		2263	C<IO::AIO::MS_RELATIME>, C<IO::AIO::MS_KERNMOUNT>, C<IO::AIO::MS_I_VERSION>, C<IO::AIO::MS_STRICTATIME>,
		2264	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
		2265	C<IO::AIO::MS_MGC_MSK>.
		2266
		2267	=item $retval = IO::AIO::umount $path, $flags = 0
		2268
		2269	Invokes the GNU/Linux C<umount> or C<umount2> syscalls. Always calls
		2270	C<umount> if C<$flags> is C<0>, otherwqise always tries to call
		2271	C<umount2>.
		2272
		2273	The following C<$flags> are available:
		2274
		2275	C<IO::AIO::MNT_FORCE>, C<IO::AIO::MNT_DETACH>, C<IO::AIO::MNT_EXPIRE> and C<IO::AIO::UMOUNT_NOFOLLOW>.
		2276
		2277	=item $numfd = IO::AIO::get_fdlimit
		2278
		2279	Tries to find the current file descriptor limit and returns it, or
		2280	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2281	the highest valid file descriptor number.
		2282
		2283	=item IO::AIO::min_fdlimit [$numfd]
		2284
		2285	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2286	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2287	is missing, it will try to set a very high limit, although this is not
		2288	recommended when you know the actual minimum that you require.
		2289
		2290	If the limit cannot be raised enough, the function makes a best-effort
		2291	attempt to increase the limit as much as possible, using various
		2292	tricks, while still failing. You can query the resulting limit using
		2293	C<IO::AIO::get_fdlimit>.
		2294
		2295	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2296	true.
1795		2297
1796	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2298	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1797		2299
1798	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2300	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1799	but is blocking (this makes most sense if you know the input data is	2301	but is blocking (this makes most sense if you know the input data is
…		…
1816	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2318	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1817		2319
1818	Simply calls the C<posix_madvise> function (see its	2320	Simply calls the C<posix_madvise> function (see its
1819	manpage for details). The following advice constants are	2321	manpage for details). The following advice constants are
1820	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2322	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1821	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2323	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2324	C<IO::AIO::MADV_DONTNEED>.
		2325
		2326	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2327	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2328	will be reduced to fit into the C<$scalar>.
1822		2329
1823	On systems that do not implement C<posix_madvise>, this function returns	2330	On systems that do not implement C<posix_madvise>, this function returns
1824	ENOSYS, otherwise the return value of C<posix_madvise>.	2331	ENOSYS, otherwise the return value of C<posix_madvise>.
1825		2332
1826	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2333	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
…		…
1828	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2335	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1829	$scalar (see its manpage for details). The following protect	2336	$scalar (see its manpage for details). The following protect
1830	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2337	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1831	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2338	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1832		2339
		2340	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2341	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2342	will be reduced to fit into the C<$scalar>.
		2343
1833	On systems that do not implement C<mprotect>, this function returns	2344	On systems that do not implement C<mprotect>, this function returns
1834	ENOSYS, otherwise the return value of C<mprotect>.	2345	ENOSYS, otherwise the return value of C<mprotect>.
1835		2346
1836	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2347	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1837		2348
1838	Memory-maps a file (or anonymous memory range) and attaches it to the	2349	Memory-maps a file (or anonymous memory range) and attaches it to the
1839	given C<$scalar>, which will act like a string scalar.	2350	given C<$scalar>, which will act like a string scalar. Returns true on
		2351	success, and false otherwise.
1840		2352
		2353	The scalar must exist, but its contents do not matter - this means you
		2354	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2355	the scalar first.
		2356
1841	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2357	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1842	change the string length, and most read-only operations such as copying it	2358	which don't change the string length, and most read-only operations such
1843	or searching it with regexes and so on.	2359	as copying it or searching it with regexes and so on.
1844		2360
1845	Anything else is unsafe and will, at best, result in memory leaks.	2361	Anything else is unsafe and will, at best, result in memory leaks.
1846		2362
1847	The memory map associated with the C<$scalar> is automatically removed	2363	The memory map associated with the C<$scalar> is automatically removed
1848	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2364	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1849	C<IO::AIO::munmap> functions are called.	2365	or C<IO::AIO::munmap> functions are called on it.
1850		2366
1851	This calls the C<mmap>(2) function internally. See your system's manual	2367	This calls the C<mmap>(2) function internally. See your system's manual
1852	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2368	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1853		2369
1854	The C<$length> must be larger than zero and smaller than the actual	2370	The C<$length> must be larger than zero and smaller than the actual
1855	filesize.	2371	filesize.
1856		2372
1857	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2373	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1858	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2374	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1859		2375
1860	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2376	C<$flags> can be a combination of
1861	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2377	C<IO::AIO::MAP_SHARED> or
1862	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2378	C<IO::AIO::MAP_PRIVATE>,
		2379	or a number of system-specific flags (when not available, the are C<0>):
1863	(which is set to C<MAP_ANON> if your system only provides this	2380	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1864	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2381	C<IO::AIO::MAP_LOCKED>,
1865	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2382	C<IO::AIO::MAP_NORESERVE>,
		2383	C<IO::AIO::MAP_POPULATE>,
1866	C<IO::AIO::MAP_NONBLOCK>	2384	C<IO::AIO::MAP_NONBLOCK>,
		2385	C<IO::AIO::MAP_FIXED>,
		2386	C<IO::AIO::MAP_GROWSDOWN>,
		2387	C<IO::AIO::MAP_32BIT>,
		2388	C<IO::AIO::MAP_HUGETLB>,
		2389	C<IO::AIO::MAP_STACK>,
		2390	C<IO::AIO::MAP_FIXED_NOREPLACE>,
		2391	C<IO::AIO::MAP_SHARED_VALIDATE>,
		2392	C<IO::AIO::MAP_SYNC> or
		2393	C<IO::AIO::MAP_UNINITIALIZED>.
1867		2394
1868	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2395	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1869		2396
1870	C<$offset> is the offset from the start of the file - it generally must be	2397	C<$offset> is the offset from the start of the file - it generally must be
1871	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2398	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1885		2412
1886	=item IO::AIO::munmap $scalar	2413	=item IO::AIO::munmap $scalar
1887		2414
1888	Removes a previous mmap and undefines the C<$scalar>.	2415	Removes a previous mmap and undefines the C<$scalar>.
1889		2416
		2417	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2418
		2419	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2420	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2421	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2422
		2423	Returns true if successful, and false otherwise. If the underlying mmapped
		2424	region has changed address, then the true value has the numerical value
		2425	C<1>, otherwise it has the numerical value C<0>:
		2426
		2427	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2428	or die "mremap: $!";
		2429
		2430	if ($success*1) {
		2431	warn "scalar has chanegd address in memory\n";
		2432	}
		2433
		2434	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2435	implemented, but not supported and might go away in a future version.
		2436
		2437	On systems where this call is not supported or is not emulated, this call
		2438	returns falls and sets C<$!> to C<ENOSYS>.
		2439
		2440	=item IO::AIO::mlockall $flags
		2441
		2442	Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
		2443	but is blocking.
		2444
1890	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef	2445	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1891		2446
1892	Calls the C<munlock> function, undoing the effects of a previous	2447	Calls the C<munlock> function, undoing the effects of a previous
1893	C<aio_mlock> call (see its description for details).	2448	C<aio_mlock> call (see its description for details).
1894		2449
…		…
1896		2451
1897	Calls the C<munlockall> function.	2452	Calls the C<munlockall> function.
1898		2453
1899	On systems that do not implement C<munlockall>, this function returns	2454	On systems that do not implement C<munlockall>, this function returns
1900	ENOSYS, otherwise the return value of C<munlockall>.	2455	ENOSYS, otherwise the return value of C<munlockall>.
		2456
		2457	=item $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		2458
		2459	Uses the GNU/Linux C<accept4(2)> syscall, if available, to accept a socket
		2460	and return the new file handle on success, or sets C<$!> and returns
		2461	C<undef> on error.
		2462
		2463	The remote name of the new socket will be stored in C<$sockaddr>, which
		2464	will be extended to allow for at least C<$sockaddr_maxlen> octets. If the
		2465	socket name does not fit into C<$sockaddr_maxlen> octets, this is signaled
		2466	by returning a longer string in C<$sockaddr>, which might or might not be
		2467	truncated.
		2468
		2469	To accept name-less sockets, use C<undef> for C<$sockaddr> and C<0> for
		2470	C<$sockaddr_maxlen>.
		2471
		2472	The main reasons to use this syscall rather than portable C<accept(2)>
		2473	are that you can specify C<SOCK_NONBLOCK> and/or C<SOCK_CLOEXEC>
		2474	flags and you can accept name-less sockets by specifying C<0> for
		2475	C<$sockaddr_maxlen>, which is sadly not possible with perl's interface to
		2476	C<accept>.
		2477
		2478	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2479
		2480	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2481	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2482	should be the file offset.
		2483
		2484	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2485	silently corrupt the data in this case.
		2486
		2487	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2488	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2489	C<IO::AIO::SPLICE_F_GIFT>.
		2490
		2491	See the C<splice(2)> manpage for details.
		2492
		2493	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2494
		2495	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2496	description for C<IO::AIO::splice> above for details.
		2497
		2498	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2499
		2500	Attempts to query or change the pipe buffer size. Obviously works only
		2501	on pipes, and currently works only on GNU/Linux systems, and fails with
		2502	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2503	size on other systems, drop me a note.
		2504
		2505	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2506
		2507	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2508	C<$flags> is missing or C<0>, then this should be the same as a call to
		2509	perl's built-in C<pipe> function and create a new pipe, and works on
		2510	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2511	(..., 4096, O_BINARY)>.
		2512
		2513	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2514	the given flags (Linux 2.6.27, glibc 2.9).
		2515
		2516	On success, the read and write file handles are returned.
		2517
		2518	On error, nothing will be returned. If the pipe2 syscall is missing and
		2519	C<$flags> is non-zero, fails with C<ENOSYS>.
		2520
		2521	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2522	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2523	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2524
		2525	Example: create a pipe race-free w.r.t. threads and fork:
		2526
		2527	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2528	or die "pipe2: $!\n";
		2529
		2530	=item $fh = IO::AIO::memfd_create $pathname[, $flags]
		2531
		2532	This is a direct interface to the Linux L<memfd_create(2)> system
		2533	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2534	should be C<IO::AIO::MFD_CLOEXEC>.
		2535
		2536	On success, the new memfd filehandle is returned, otherwise returns
		2537	C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
		2538
		2539	Please refer to L<memfd_create(2)> for more info on this call.
		2540
		2541	The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
		2542	C<IO::AIO::MFD_ALLOW_SEALING>, C<IO::AIO::MFD_HUGETLB>,
		2543	C<IO::AIO::MFD_HUGETLB_2MB> and C<IO::AIO::MFD_HUGETLB_1GB>.
		2544
		2545	Example: create a new memfd.
		2546
		2547	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2548	or die "memfd_create: $!\n";
		2549
		2550	=item $fh = IO::AIO::pidfd_open $pid[, $flags]
		2551
		2552	This is an interface to the Linux L<pidfd_open(2)> system call. The
		2553	default for C<$flags> is C<0>.
		2554
		2555	On success, a new pidfd filehandle is returned (that is already set to
		2556	close-on-exec), otherwise returns C<undef>. If the syscall is missing,
		2557	fails with C<ENOSYS>.
		2558
		2559	Example: open pid 6341 as pidfd.
		2560
		2561	my $fh = IO::AIO::pidfd_open 6341
		2562	or die "pidfd_open: $!\n";
		2563
		2564	=item $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		2565
		2566	This is an interface to the Linux L<pidfd_send_signal> system call. The
		2567	default for C<$siginfo> is C<undef> and the default for C<$flags> is C<0>.
		2568
		2569	Returns the system call status. If the syscall is missing, fails with
		2570	C<ENOSYS>.
		2571
		2572	When specified, C<$siginfo> must be a reference to a hash with one or more
		2573	of the following members:
		2574
		2575	=over
		2576
		2577	=item code - the C<si_code> member
		2578
		2579	=item pid - the C<si_pid> member
		2580
		2581	=item uid - the C<si_uid> member
		2582
		2583	=item value_int - the C<si_value.sival_int> member
		2584
		2585	=item value_ptr - the C<si_value.sival_ptr> member, specified as an integer
		2586
		2587	=back
		2588
		2589	Example: send a SIGKILL to the specified process.
		2590
		2591	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
		2592	and die "pidfd_send_signal: $!\n";
		2593
		2594	Example: send a SIGKILL to the specified process with extra data.
		2595
		2596	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
		2597	and die "pidfd_send_signal: $!\n";
		2598
		2599	=item $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		2600
		2601	This is an interface to the Linux L<pidfd_getfd> system call. The default
		2602	for C<$flags> is C<0>.
		2603
		2604	On success, returns a dup'ed copy of the target file descriptor (specified
		2605	as an integer) returned (that is already set to close-on-exec), otherwise
		2606	returns C<undef>. If the syscall is missing, fails with C<ENOSYS>.
		2607
		2608	Example: get a copy of standard error of another process and print soemthing to it.
		2609
		2610	my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
		2611	or die "pidfd_getfd: $!\n";
		2612	print $errfh "stderr\n";
		2613
		2614	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2615
		2616	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2617	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2618
		2619	On success, the new eventfd filehandle is returned, otherwise returns
		2620	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2621
		2622	Please refer to L<eventfd(2)> for more info on this call.
		2623
		2624	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2625	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2626
		2627	Example: create a new eventfd filehandle:
		2628
		2629	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2630	or die "eventfd: $!\n";
		2631
		2632	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2633
		2634	This is a direct interface to the Linux L<timerfd_create(2)> system
		2635	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2636	should be C<IO::AIO::TFD_CLOEXEC>.
		2637
		2638	On success, the new timerfd filehandle is returned, otherwise returns
		2639	C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
		2640
		2641	Please refer to L<timerfd_create(2)> for more info on this call.
		2642
		2643	The following C<$clockid> values are
		2644	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2645	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2646	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2647	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2648
		2649	The following C<$flags> values are available (Linux
		2650	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2651
		2652	Example: create a new timerfd and set it to one-second repeated alarms,
		2653	then wait for two alarms:
		2654
		2655	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2656	or die "timerfd_create: $!\n";
		2657
		2658	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2659	or die "timerfd_settime: $!\n";
		2660
		2661	for (1..2) {
		2662	8 == sysread $fh, my $buf, 8
		2663	or die "timerfd read failure\n";
		2664
		2665	printf "number of expirations (likely 1): %d\n",
		2666	unpack "Q", $buf;
		2667	}
		2668
		2669	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2670
		2671	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2672	call. Please refer to its manpage for more info on this call.
		2673
		2674	The new itimerspec is specified using two (possibly fractional) second
		2675	values, C<$new_interval> and C<$new_value>).
		2676
		2677	On success, the current interval and value are returned (as per
		2678	C<timerfd_gettime>). On failure, the empty list is returned.
		2679
		2680	The following C<$flags> values are
		2681	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2682	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2683
		2684	See C<IO::AIO::timerfd_create> for a full example.
		2685
		2686	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2687
		2688	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2689	call. Please refer to its manpage for more info on this call.
		2690
		2691	On success, returns the current values of interval and value for the given
		2692	timerfd (as potentially fractional second values). On failure, the empty
		2693	list is returned.
1901		2694
1902	=back	2695	=back
1903		2696
1904	=cut	2697	=cut
1905		2698
…		…
1971	the process will result in undefined behaviour. Calling it at any time	2764	the process will result in undefined behaviour. Calling it at any time
1972	will also result in any undefined (by POSIX) behaviour.	2765	will also result in any undefined (by POSIX) behaviour.
1973		2766
1974	=back	2767	=back
1975		2768
		2769	=head2 LINUX-SPECIFIC CALLS
		2770
		2771	When a call is documented as "linux-specific" then this means it
		2772	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2773	availability and compatibility of such calls regardless of the platform
		2774	it is compiled on, so platforms such as FreeBSD which often implement
		2775	these calls will work. When in doubt, call them and see if they fail wth
		2776	C<ENOSYS>.
		2777
1976	=head2 MEMORY USAGE	2778	=head2 MEMORY USAGE
1977		2779
1978	Per-request usage:	2780	Per-request usage:
1979		2781
1980	Each aio request uses - depending on your architecture - around 100-200	2782	Each aio request uses - depending on your architecture - around 100-200
…		…
1992	temporary buffers, and each thread requires a stack and other data	2794	temporary buffers, and each thread requires a stack and other data
1993	structures (usually around 16k-128k, depending on the OS).	2795	structures (usually around 16k-128k, depending on the OS).
1994		2796
1995	=head1 KNOWN BUGS	2797	=head1 KNOWN BUGS
1996		2798
1997	Known bugs will be fixed in the next release.	2799	Known bugs will be fixed in the next release :)
		2800
		2801	=head1 KNOWN ISSUES
		2802
		2803	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2804	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2805	non-created hash slots or other scalars I didn't think of. It's best to
		2806	avoid such and either use scalar variables or making sure that the scalar
		2807	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2808
		2809	I am not sure anything can be done about this, so this is considered a
		2810	known issue, rather than a bug.
1998		2811
1999	=head1 SEE ALSO	2812	=head1 SEE ALSO
2000		2813
2001	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2814	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
2002	more natural syntax.	2815	more natural syntax and L<IO::FDPass> for file descriptor passing.
2003		2816
2004	=head1 AUTHOR	2817	=head1 AUTHOR
2005		2818
2006	Marc Lehmann <schmorp@schmorp.de>	2819	Marc Lehmann <schmorp@schmorp.de>
2007	http://home.schmorp.de/	2820	http://home.schmorp.de/

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