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Revision 1.239 by root, Thu Dec 13 02:26:28 2012 UTC vs.
Revision 1.317 by root, Sun Sep 25 16:30:50 2022 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 = '4.18';	176	our $VERSION = 4.79;
174		177
175	our @AIO_REQ = qw(aio_sendfile aio_seek 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_allocate	181	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
179	aio_pathsync aio_readahead aio_fiemap	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
…		…
228	aio_unlink $pathname, $callback->($status)	237	aio_unlink $pathname, $callback->($status)
229	aio_mknod $pathname, $mode, $dev, $callback->($status)	238	aio_mknod $pathname, $mode, $dev, $callback->($status)
230	aio_link $srcpath, $dstpath, $callback->($status)	239	aio_link $srcpath, $dstpath, $callback->($status)
231	aio_symlink $srcpath, $dstpath, $callback->($status)	240	aio_symlink $srcpath, $dstpath, $callback->($status)
232	aio_readlink $pathname, $callback->($link)	241	aio_readlink $pathname, $callback->($link)
233	aio_realpath $pathname, $callback->($link)	242	aio_realpath $pathname, $callback->($path)
234	aio_rename $srcpath, $dstpath, $callback->($status)	243	aio_rename $srcpath, $dstpath, $callback->($status)
		244	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
235	aio_mkdir $pathname, $mode, $callback->($status)	245	aio_mkdir $pathname, $mode, $callback->($status)
236	aio_rmdir $pathname, $callback->($status)	246	aio_rmdir $pathname, $callback->($status)
237	aio_readdir $pathname, $callback->($entries)	247	aio_readdir $pathname, $callback->($entries)
238	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	248	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
239	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	249	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
…		…
241	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)	251	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
242	aio_load $pathname, $data, $callback->($status)	252	aio_load $pathname, $data, $callback->($status)
243	aio_copy $srcpath, $dstpath, $callback->($status)	253	aio_copy $srcpath, $dstpath, $callback->($status)
244	aio_move $srcpath, $dstpath, $callback->($status)	254	aio_move $srcpath, $dstpath, $callback->($status)
245	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)
246	aio_sync $callback->($status)	258	aio_sync $callback->($status)
247	aio_syncfs $fh, $callback->($status)	259	aio_syncfs $fh, $callback->($status)
248	aio_fsync $fh, $callback->($status)	260	aio_fsync $fh, $callback->($status)
249	aio_fdatasync $fh, $callback->($status)	261	aio_fdatasync $fh, $callback->($status)
250	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	262	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
251	aio_pathsync $pathname, $callback->($status)	263	aio_pathsync $pathname, $callback->($status)
252	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	264	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
253	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	265	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
254	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	266	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
255	aio_mlockall $flags, $callback->($status)	267	aio_mlockall $flags, $callback->($status)
256	aio_group $callback->(...)	268	aio_group $callback->(...)
257	aio_nop $callback->()	269	aio_nop $callback->()
…		…
271	IO::AIO::idle_timeout $seconds	283	IO::AIO::idle_timeout $seconds
272	IO::AIO::max_outstanding $maxreqs	284	IO::AIO::max_outstanding $maxreqs
273	IO::AIO::nreqs	285	IO::AIO::nreqs
274	IO::AIO::nready	286	IO::AIO::nready
275	IO::AIO::npending	287	IO::AIO::npending
		288	IO::AIO::reinit
		289
		290	$nfd = IO::AIO::get_fdlimit
		291	IO::AIO::min_fdlimit $nfd
276		292
277	IO::AIO::sendfile $ofh, $ifh, $offset, $count	293	IO::AIO::sendfile $ofh, $ifh, $offset, $count
278	IO::AIO::fadvise $fh, $offset, $len, $advice	294	IO::AIO::fadvise $fh, $offset, $len, $advice
		295	IO::AIO::fexecve $fh, $argv, $envp
		296
279	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]	297	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
280	IO::AIO::munmap $scalar	298	IO::AIO::munmap $scalar
		299	IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
281	IO::AIO::madvise $scalar, $offset, $length, $advice	300	IO::AIO::madvise $scalar, $offset, $length, $advice
282	IO::AIO::mprotect $scalar, $offset, $length, $protect	301	IO::AIO::mprotect $scalar, $offset, $length, $protect
283	IO::AIO::munlock $scalar, $offset = 0, $length = undef	302	IO::AIO::munlock $scalar, $offset = 0, $length = undef
284	IO::AIO::munlockall	303	IO::AIO::munlockall
		304
		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
285		334
286	=head2 API NOTES	335	=head2 API NOTES
287		336
288	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
289	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,
…		…
395	following POSIX and non-POSIX constants are available (missing ones on	444	following POSIX and non-POSIX constants are available (missing ones on
396	your system are, as usual, C<0>):	445	your system are, as usual, C<0>):
397		446
398	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,	447	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
399	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,	448	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
400	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.	449	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
401		450
402		451
403	=item aio_close $fh, $callback->($status)	452	=item aio_close $fh, $callback->($status)
404		453
405	Asynchronously close a file and call the callback with the result	454	Asynchronously close a file and call the callback with the result
…		…
440	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	489	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
441		490
442	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	491	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
443		492
444	Reads or writes C<$length> bytes from or to the specified C<$fh> and	493	Reads or writes C<$length> bytes from or to the specified C<$fh> and
445	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	494	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
446	and calls the callback without the actual number of bytes read (or -1 on	495	calls the callback with the actual number of bytes transferred (or -1 on
447	error, just like the syscall).	496	error, just like the syscall).
448		497
449	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	498	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
450	offset plus the actual number of bytes read.	499	offset plus the actual number of bytes read.
451		500
…		…
509	As native sendfile syscalls (as practically any non-POSIX interface hacked	558	As native sendfile syscalls (as practically any non-POSIX interface hacked
510	together in a hurry to improve benchmark numbers) tend to be rather buggy	559	together in a hurry to improve benchmark numbers) tend to be rather buggy
511	on many systems, this implementation tries to work around some known bugs	560	on many systems, this implementation tries to work around some known bugs
512	in Linux and FreeBSD kernels (probably others, too), but that might fail,	561	in Linux and FreeBSD kernels (probably others, too), but that might fail,
513	so you really really should check the return value of C<aio_sendfile> -	562	so you really really should check the return value of C<aio_sendfile> -
514	fewre bytes than expected might have been transferred.	563	fewer bytes than expected might have been transferred.
515		564
516		565
517	=item aio_readahead $fh,$offset,$length, $callback->($retval)	566	=item aio_readahead $fh,$offset,$length, $callback->($retval)
518		567
519	C<aio_readahead> populates the page cache with data from a file so that	568	C<aio_readahead> populates the page cache with data from a file so that
…		…
523	whole pages, so that offset is effectively rounded down to a page boundary	572	whole pages, so that offset is effectively rounded down to a page boundary
524	and bytes are read up to the next page boundary greater than or equal to	573	and bytes are read up to the next page boundary greater than or equal to
525	(off-set+length). C<aio_readahead> does not read beyond the end of the	574	(off-set+length). C<aio_readahead> does not read beyond the end of the
526	file. The current file offset of the file is left unchanged.	575	file. The current file offset of the file is left unchanged.
527		576
528	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	577	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
529	emulated by simply reading the data, which would have a similar effect.	578	be emulated by simply reading the data, which would have a similar effect.
530		579
531		580
532	=item aio_stat $fh_or_path, $callback->($status)	581	=item aio_stat $fh_or_path, $callback->($status)
533		582
534	=item aio_lstat $fh, $callback->($status)	583	=item aio_lstat $fh, $callback->($status)
535		584
536	Works like perl's C<stat> or C<lstat> in void context. The callback will	585	Works almost exactly like perl's C<stat> or C<lstat> in void context. The
537	be called after the stat and the results will be available using C<stat _>	586	callback will be called after the stat and the results will be available
538	or C<-s _> etc...	587	using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
		588	and C<-T>).
539		589
540	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,	590	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
541	for an explanation.	591	for an explanation.
542		592
543	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	593	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
…		…
550	behaviour).	600	behaviour).
551		601
552	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,	602	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
553	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,	603	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
554	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.	604	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		605
		606	To access higher resolution stat timestamps, see L<SUBSECOND STAT TIME
		607	ACCESS>.
555		608
556	Example: Print the length of F</etc/passwd>:	609	Example: Print the length of F</etc/passwd>:
557		610
558	aio_stat "/etc/passwd", sub {	611	aio_stat "/etc/passwd", sub {
559	$_[0] and die "stat failed: $!";	612	$_[0] and die "stat failed: $!";
…		…
603	namemax => 255,	656	namemax => 255,
604	frsize => 1024,	657	frsize => 1024,
605	fsid => 1810	658	fsid => 1810
606	}	659	}
607		660
608	Here is a (likely partial) list of fsid values used by Linux - it is safe
609	to hardcode these when the $^O is C<linux>:
610
611	0x0000adf5 adfs
612	0x0000adff affs
613	0x5346414f afs
614	0x09041934 anon-inode filesystem
615	0x00000187 autofs
616	0x42465331 befs
617	0x1badface bfs
618	0x42494e4d binfmt_misc
619	0x9123683e btrfs
620	0x0027e0eb cgroupfs
621	0xff534d42 cifs
622	0x73757245 coda
623	0x012ff7b7 coh
624	0x28cd3d45 cramfs
625	0x453dcd28 cramfs-wend (wrong endianness)
626	0x64626720 debugfs
627	0x00001373 devfs
628	0x00001cd1 devpts
629	0x0000f15f ecryptfs
630	0x00414a53 efs
631	0x0000137d ext
632	0x0000ef53 ext2/ext3
633	0x0000ef51 ext2
634	0x00004006 fat
635	0x65735546 fuseblk
636	0x65735543 fusectl
637	0x0bad1dea futexfs
638	0x01161970 gfs2
639	0x47504653 gpfs
640	0x00004244 hfs
641	0xf995e849 hpfs
642	0x958458f6 hugetlbfs
643	0x2bad1dea inotifyfs
644	0x00009660 isofs
645	0x000072b6 jffs2
646	0x3153464a jfs
647	0x6b414653 k-afs
648	0x0bd00bd0 lustre
649	0x0000137f minix
650	0x0000138f minix 30 char names
651	0x00002468 minix v2
652	0x00002478 minix v2 30 char names
653	0x00004d5a minix v3
654	0x19800202 mqueue
655	0x00004d44 msdos
656	0x0000564c novell
657	0x00006969 nfs
658	0x6e667364 nfsd
659	0x00003434 nilfs
660	0x5346544e ntfs
661	0x00009fa1 openprom
662	0x7461636F ocfs2
663	0x00009fa0 proc
664	0x6165676c pstorefs
665	0x0000002f qnx4
666	0x858458f6 ramfs
667	0x52654973 reiserfs
668	0x00007275 romfs
669	0x67596969 rpc_pipefs
670	0x73636673 securityfs
671	0xf97cff8c selinux
672	0x0000517b smb
673	0x534f434b sockfs
674	0x73717368 squashfs
675	0x62656572 sysfs
676	0x012ff7b6 sysv2
677	0x012ff7b5 sysv4
678	0x01021994 tmpfs
679	0x15013346 udf
680	0x00011954 ufs
681	0x54190100 ufs byteswapped
682	0x00009fa2 usbdevfs
683	0x01021997 v9fs
684	0xa501fcf5 vxfs
685	0xabba1974 xenfs
686	0x012ff7b4 xenix
687	0x58465342 xfs
688	0x012fd16d xia
689
690	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	661	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
691		662
692	Works like perl's C<utime> function (including the special case of $atime	663	Works like perl's C<utime> function (including the special case of $atime
693	and $mtime being undef). Fractional times are supported if the underlying	664	and $mtime being undef). Fractional times are supported if the underlying
694	syscalls support them.	665	syscalls support them.
695		666
696	When called with a pathname, uses utimes(2) if available, otherwise	667	When called with a pathname, uses utimensat(2) or utimes(2) if available,
697	utime(2). If called on a file descriptor, uses futimes(2) if available,	668	otherwise utime(2). If called on a file descriptor, uses futimens(2)
698	otherwise returns ENOSYS, so this is not portable.	669	or futimes(2) if available, otherwise returns ENOSYS, so this is not
		670	portable.
699		671
700	Examples:	672	Examples:
701		673
702	# set atime and mtime to current time (basically touch(1)):	674	# set atime and mtime to current time (basically touch(1)):
703	aio_utime "path", undef, undef;	675	aio_utime "path", undef, undef;
…		…
723	Works like truncate(2) or ftruncate(2).	695	Works like truncate(2) or ftruncate(2).
724		696
725		697
726	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)	698	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
727		699
728	Allocates or freed disk space according to the C<$mode> argument. See the	700	Allocates or frees disk space according to the C<$mode> argument. See the
729	linux C<fallocate> docuemntation for details.	701	linux C<fallocate> documentation for details.
730		702
731	C<$mode> can currently be C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE>	703	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
732	to allocate space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE |	704	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
733	IO::AIO::FALLOC_FL_KEEP_SIZE>, to deallocate a file range.	705	to deallocate a file range.
		706
		707	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		708	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		709	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		710	to unshare shared blocks (see your L<fallocate(2)> manpage).
734		711
735	The file system block size used by C<fallocate> is presumably the	712	The file system block size used by C<fallocate> is presumably the
736	C<f_bsize> returned by C<statvfs>.	713	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		714	can dictate other limitations.
737		715
738	If C<fallocate> isn't available or cannot be emulated (currently no	716	If C<fallocate> isn't available or cannot be emulated (currently no
739	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.	717	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
740		718
741		719
…		…
795	=item aio_rename $srcpath, $dstpath, $callback->($status)	773	=item aio_rename $srcpath, $dstpath, $callback->($status)
796		774
797	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	775	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
798	rename(2) and call the callback with the result code.	776	rename(2) and call the callback with the result code.
799		777
		778	On systems that support the AIO::WD working directory abstraction
		779	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		780	of failing, C<rename> is called on the absolute path of C<$wd>.
		781
		782
		783	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		784
		785	Basically a version of C<aio_rename> with an additional C<$flags>
		786	argument. Calling this with C<$flags=0> is the same as calling
		787	C<aio_rename>.
		788
		789	Non-zero flags are currently only supported on GNU/Linux systems that
		790	support renameat2. Other systems fail with C<ENOSYS> in this case.
		791
		792	The following constants are available (missing ones are, as usual C<0>),
		793	see renameat2(2) for details:
		794
		795	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		796	and C<IO::AIO::RENAME_WHITEOUT>.
		797
800		798
801	=item aio_mkdir $pathname, $mode, $callback->($status)	799	=item aio_mkdir $pathname, $mode, $callback->($status)
802		800
803	Asynchronously mkdir (create) a directory and call the callback with	801	Asynchronously mkdir (create) a directory and call the callback with
804	the result code. C<$mode> will be modified by the umask at the time the	802	the result code. C<$mode> will be modified by the umask at the time the
…		…
808	=item aio_rmdir $pathname, $callback->($status)	806	=item aio_rmdir $pathname, $callback->($status)
809		807
810	Asynchronously rmdir (delete) a directory and call the callback with the	808	Asynchronously rmdir (delete) a directory and call the callback with the
811	result code.	809	result code.
812		810
		811	On systems that support the AIO::WD working directory abstraction
		812	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		813	C<rmdir> is called on the absolute path of C<$wd>.
		814
813		815
814	=item aio_readdir $pathname, $callback->($entries)	816	=item aio_readdir $pathname, $callback->($entries)
815		817
816	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	818	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
817	directory (i.e. opendir + readdir + closedir). The entries will not be	819	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
832		834
833	=over 4	835	=over 4
834		836
835	=item IO::AIO::READDIR_DENTS	837	=item IO::AIO::READDIR_DENTS
836		838
837	When this flag is off, then the callback gets an arrayref consisting of	839	Normally the callback gets an arrayref consisting of names only (as
838	names only (as with C<aio_readdir>), otherwise it gets an arrayref with	840	with C<aio_readdir>). If this flag is set, then the callback gets an
839	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	841	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
840	entry in more detail.	842	single directory entry in more detail:
841		843
842	C<$name> is the name of the entry.	844	C<$name> is the name of the entry.
843		845
844	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	846	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
845		847
846	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	848	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
847	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	849	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
848	C<IO::AIO::DT_WHT>.	850	C<IO::AIO::DT_WHT>.
849		851
850	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	852	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
851	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	853	to know, you have to run stat yourself. Also, for speed/memory reasons,
852	scalars are read-only: you can not modify them.	854	the C<$type> scalars are read-only: you must not modify them.
853		855
854	C<$inode> is the inode number (which might not be exact on systems with 64	856	C<$inode> is the inode number (which might not be exact on systems with 64
855	bit inode numbers and 32 bit perls). This field has unspecified content on	857	bit inode numbers and 32 bit perls). This field has unspecified content on
856	systems that do not deliver the inode information.	858	systems that do not deliver the inode information.
857		859
…		…
868	short names are tried first.	870	short names are tried first.
869		871
870	=item IO::AIO::READDIR_STAT_ORDER	872	=item IO::AIO::READDIR_STAT_ORDER
871		873
872	When this flag is set, then the names will be returned in an order	874	When this flag is set, then the names will be returned in an order
873	suitable for stat()'ing each one. That is, when you plan to stat()	875	suitable for stat()'ing each one. That is, when you plan to stat() most or
874	all files in the given directory, then the returned order will likely	876	all files in the given directory, then the returned order will likely be
875	be fastest.	877	faster.
876		878
877	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then	879	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
878	the likely dirs come first, resulting in a less optimal stat order.	880	then the likely dirs come first, resulting in a less optimal stat order
		881	for stat'ing all entries, but likely a more optimal order for finding
		882	subdirectories.
879		883
880	=item IO::AIO::READDIR_FOUND_UNKNOWN	884	=item IO::AIO::READDIR_FOUND_UNKNOWN
881		885
882	This flag should not be set when calling C<aio_readdirx>. Instead, it	886	This flag should not be set when calling C<aio_readdirx>. Instead, it
883	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	887	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
…		…
885	C<$type>'s are known, which can be used to speed up some algorithms.	889	C<$type>'s are known, which can be used to speed up some algorithms.
886		890
887	=back	891	=back
888		892
889		893
		894	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		895
		896	Opens, reads and closes the given file. The data is put into C<$data>,
		897	which is resized as required.
		898
		899	If C<$offset> is negative, then it is counted from the end of the file.
		900
		901	If C<$length> is zero, then the remaining length of the file is
		902	used. Also, in this case, the same limitations to modifying C<$data> apply
		903	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		904	with C<substr>. If the size of the file is known, specifying a non-zero
		905	C<$length> results in a performance advantage.
		906
		907	This request is similar to the older C<aio_load> request, but since it is
		908	a single request, it might be more efficient to use.
		909
		910	Example: load F</etc/passwd> into C<$passwd>.
		911
		912	my $passwd;
		913	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		914	$_[0] >= 0
		915	or die "/etc/passwd: $!\n";
		916
		917	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		918	print $passwd;
		919	};
		920	IO::AIO::flush;
		921
		922
890	=item aio_load $pathname, $data, $callback->($status)	923	=item aio_load $pathname, $data, $callback->($status)
891		924
892	This is a composite request that tries to fully load the given file into	925	This is a composite request that tries to fully load the given file into
893	memory. Status is the same as with aio_read.	926	memory. Status is the same as with aio_read.
		927
		928	Using C<aio_slurp> might be more efficient, as it is a single request.
894		929
895	=cut	930	=cut
896		931
897	sub aio_load($$;$) {	932	sub aio_load($$;$) {
898	my ($path, undef, $cb) = @_;	933	my ($path, undef, $cb) = @_;
…		…
918	=item aio_copy $srcpath, $dstpath, $callback->($status)	953	=item aio_copy $srcpath, $dstpath, $callback->($status)
919		954
920	Try to copy the I<file> (directories not supported as either source or	955	Try to copy the I<file> (directories not supported as either source or
921	destination) from C<$srcpath> to C<$dstpath> and call the callback with	956	destination) from C<$srcpath> to C<$dstpath> and call the callback with
922	a status of C<0> (ok) or C<-1> (error, see C<$!>).	957	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		958
		959	Existing destination files will be truncated.
923		960
924	This is a composite request that creates the destination file with	961	This is a composite request that creates the destination file with
925	mode 0200 and copies the contents of the source file into it using	962	mode 0200 and copies the contents of the source file into it using
926	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	963	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
927	uid/gid, in that order.	964	uid/gid, in that order.
…		…
1037	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1074	Scans a directory (similar to C<aio_readdir>) but additionally tries to
1038	efficiently separate the entries of directory C<$path> into two sets of	1075	efficiently separate the entries of directory C<$path> into two sets of
1039	names, directories you can recurse into (directories), and ones you cannot	1076	names, directories you can recurse into (directories), and ones you cannot
1040	recurse into (everything else, including symlinks to directories).	1077	recurse into (everything else, including symlinks to directories).
1041		1078
1042	C<aio_scandir> is a composite request that creates of many sub requests_	1079	C<aio_scandir> is a composite request that generates many sub requests.
1043	C<$maxreq> specifies the maximum number of outstanding aio requests that	1080	C<$maxreq> specifies the maximum number of outstanding aio requests that
1044	this function generates. If it is C<< <= 0 >>, then a suitable default	1081	this function generates. If it is C<< <= 0 >>, then a suitable default
1045	will be chosen (currently 4).	1082	will be chosen (currently 4).
1046		1083
1047	On error, the callback is called without arguments, otherwise it receives	1084	On error, the callback is called without arguments, otherwise it receives
…		…
1111	aioreq_pri $pri;	1148	aioreq_pri $pri;
1112	add $grp aio_stat $wd, sub {	1149	add $grp aio_stat $wd, sub {
1113	return $grp->result () if $_[0];	1150	return $grp->result () if $_[0];
1114	my $now = time;	1151	my $now = time;
1115	my $hash1 = join ":", (stat _)[0,1,3,7,9];	1152	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		1153	my $rdxflags = READDIR_DIRS_FIRST;
		1154
		1155	if ((stat _)[3] < 2) {
		1156	# at least one non-POSIX filesystem exists
		1157	# that returns useful DT_type values: btrfs,
		1158	# so optimise for this here by requesting dents
		1159	$rdxflags |= READDIR_DENTS;
		1160	}
1116		1161
1117	# read the directory entries	1162	# read the directory entries
1118	aioreq_pri $pri;	1163	aioreq_pri $pri;
1119	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {	1164	add $grp aio_readdirx $wd, $rdxflags, sub {
1120	my $entries = shift	1165	my ($entries, $flags) = @_
1121	or return $grp->result ();	1166	or return $grp->result ();
		1167
		1168	if ($rdxflags & READDIR_DENTS) {
		1169	# if we requested type values, see if we can use them directly.
		1170
		1171	# if there were any DT_UNKNOWN entries then we assume we
		1172	# don't know. alternatively, we could assume that if we get
		1173	# one DT_DIR, then all directories are indeed marked with
		1174	# DT_DIR, but this seems not required for btrfs, and this
		1175	# is basically the "btrfs can't get it's act together" code
		1176	# branch.
		1177	unless ($flags & READDIR_FOUND_UNKNOWN) {
		1178	# now we have valid DT_ information for all entries,
		1179	# so use it as an optimisation without further stat's.
		1180	# they must also all be at the beginning of @$entries
		1181	# by now.
		1182
		1183	my $dirs;
		1184
		1185	if (@$entries) {
		1186	for (0 .. $#$entries) {
		1187	if ($entries->[$_][1] != DT_DIR) {
		1188	# splice out directories
		1189	$dirs = [splice @$entries, 0, $_];
		1190	last;
		1191	}
		1192	}
		1193
		1194	# if we didn't find any non-dir, then all entries are dirs
		1195	unless ($dirs) {
		1196	($dirs, $entries) = ($entries, []);
		1197	}
		1198	} else {
		1199	# directory is empty, so there are no sbdirs
		1200	$dirs = [];
		1201	}
		1202
		1203	# either splice'd the directories out or the dir was empty.
		1204	# convert dents to filenames
		1205	$_ = $_->[0] for @$dirs;
		1206	$_ = $_->[0] for @$entries;
		1207
		1208	return $grp->result ($dirs, $entries);
		1209	}
		1210
		1211	# cannot use, so return to our old ways
		1212	# by pretending we only scanned for names.
		1213	$_ = $_->[0] for @$entries;
		1214	}
1122		1215
1123	# stat the dir another time	1216	# stat the dir another time
1124	aioreq_pri $pri;	1217	aioreq_pri $pri;
1125	add $grp aio_stat $wd, sub {	1218	add $grp aio_stat $wd, sub {
1126	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1219	my $hash2 = join ":", (stat _)[0,1,3,7,9];
…		…
1213	};	1306	};
1214		1307
1215	$grp	1308	$grp
1216	}	1309	}
1217		1310
		1311	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1312
		1313	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1314
		1315	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1316	they execute asynchronously and pass the return value to the callback.
		1317
		1318	Both calls can be used for a lot of things, some of which make more sense
		1319	to run asynchronously in their own thread, while some others make less
		1320	sense. For example, calls that block waiting for external events, such
		1321	as locking, will also lock down an I/O thread while it is waiting, which
		1322	can deadlock the whole I/O system. At the same time, there might be no
		1323	alternative to using a thread to wait.
		1324
		1325	So in general, you should only use these calls for things that do
		1326	(filesystem) I/O, not for things that wait for other events (network,
		1327	other processes), although if you are careful and know what you are doing,
		1328	you still can.
		1329
		1330	The following constants are available and can be used for normal C<ioctl>
		1331	and C<fcntl> as well (missing ones are, as usual C<0>):
		1332
		1333	C<F_DUPFD_CLOEXEC>,
		1334
		1335	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1336
		1337	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1338
		1339	C<F_ADD_SEALS>, C<F_GET_SEALS>, C<F_SEAL_SEAL>, C<F_SEAL_SHRINK>, C<F_SEAL_GROW> and
		1340	C<F_SEAL_WRITE>.
		1341
		1342	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1343	C<FS_IOC_FIEMAP>.
		1344
		1345	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1346	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1347
		1348	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1349	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1350	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1351	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1352	C<FS_FL_USER_MODIFIABLE>.
		1353
		1354	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1355	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1356	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1357	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1358
		1359	C<BLKROSET>, C<BLKROGET>, C<BLKRRPART>, C<BLKGETSIZE>, C<BLKFLSBUF>, C<BLKRASET>,
		1360	C<BLKRAGET>, C<BLKFRASET>, C<BLKFRAGET>, C<BLKSECTSET>, C<BLKSECTGET>, C<BLKSSZGET>,
		1361	C<BLKBSZGET>, C<BLKBSZSET>, C<BLKGETSIZE64>,
		1362
		1363
1218	=item aio_sync $callback->($status)	1364	=item aio_sync $callback->($status)
1219		1365
1220	Asynchronously call sync and call the callback when finished.	1366	Asynchronously call sync and call the callback when finished.
1221		1367
1222	=item aio_fsync $fh, $callback->($status)	1368	=item aio_fsync $fh, $callback->($status)
…		…
1290	};	1436	};
1291		1437
1292	$grp	1438	$grp
1293	}	1439	}
1294		1440
1295	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1441	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1296		1442
1297	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1443	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1298	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1444	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1299	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1445	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1300	scalar must only be modified in-place while an aio operation is pending on	1446	scalar must only be modified in-place while an aio operation is pending on
…		…
1302		1448
1303	It calls the C<msync> function of your OS, if available, with the memory	1449	It calls the C<msync> function of your OS, if available, with the memory
1304	area starting at C<$offset> in the string and ending C<$length> bytes	1450	area starting at C<$offset> in the string and ending C<$length> bytes
1305	later. If C<$length> is negative, counts from the end, and if C<$length>	1451	later. If C<$length> is negative, counts from the end, and if C<$length>
1306	is C<undef>, then it goes till the end of the string. The flags can be	1452	is C<undef>, then it goes till the end of the string. The flags can be
1307	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1453	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1308	C<IO::AIO::MS_SYNC>.	1454	C<IO::AIO::MS_INVALIDATE>.
1309		1455
1310	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1456	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1311		1457
1312	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1458	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1313	scalars.	1459	scalars.
…		…
1343	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;	1489	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1344	aio_mlock $data; # mlock in background	1490	aio_mlock $data; # mlock in background
1345		1491
1346	=item aio_mlockall $flags, $callback->($status)	1492	=item aio_mlockall $flags, $callback->($status)
1347		1493
1348	Calls the C<mlockall> function with the given C<$flags> (a combination of	1494	Calls the C<mlockall> function with the given C<$flags> (a
1349	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).	1495	combination of C<IO::AIO::MCL_CURRENT>, C<IO::AIO::MCL_FUTURE> and
		1496	C<IO::AIO::MCL_ONFAULT>).
1350		1497
1351	On systems that do not implement C<mlockall>, this function returns C<-1>	1498	On systems that do not implement C<mlockall>, this function returns C<-1>
1352	and sets errno to C<ENOSYS>.	1499	and sets errno to C<ENOSYS>. Similarly, flag combinations not supported
		1500	by the system result in a return value of C<-1> with errno being set to
		1501	C<EINVAL>.
1353		1502
1354	Note that the corresponding C<munlockall> is synchronous and is	1503	Note that the corresponding C<munlockall> is synchronous and is
1355	documented under L<MISCELLANEOUS FUNCTIONS>.	1504	documented under L<MISCELLANEOUS FUNCTIONS>.
1356		1505
1357	Example: asynchronously lock all current and future pages into memory.	1506	Example: asynchronously lock all current and future pages into memory.
…		…
1396	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,	1545	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
1397	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,	1546	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
1398	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or	1547	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
1399	C<IO::AIO::FIEMAP_EXTENT_SHARED>.	1548	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
1400		1549
1401	At the time of this writing (Linux 3.2), this requets is unreliable unless	1550	At the time of this writing (Linux 3.2), this request is unreliable unless
1402	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing	1551	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
1403	it to return all extents of a range for files with large number of	1552	it to return all extents of a range for files with a large number of
1404	extents. The code works around all these issues if C<$count> is undef.	1553	extents. The code (only) works around all these issues if C<$count> is
		1554	C<undef>.
1405		1555
1406	=item aio_group $callback->(...)	1556	=item aio_group $callback->(...)
1407		1557
1408	This is a very special aio request: Instead of doing something, it is a	1558	This is a very special aio request: Instead of doing something, it is a
1409	container for other aio requests, which is useful if you want to bundle	1559	container for other aio requests, which is useful if you want to bundle
…		…
1493	aio_stat [$etcdir, "passwd"], sub {	1643	aio_stat [$etcdir, "passwd"], sub {
1494	# yay	1644	# yay
1495	};	1645	};
1496	};	1646	};
1497		1647
1498	That C<aio_wd> is a request and not a normal function shows that creating	1648	The fact that C<aio_wd> is a request and not a normal function shows that
1499	an IO::AIO::WD object is itself a potentially blocking operation, which is	1649	creating an IO::AIO::WD object is itself a potentially blocking operation,
1500	why it is done asynchronously.	1650	which is why it is done asynchronously.
1501		1651
1502	To stat the directory obtained with C<aio_wd> above, one could write	1652	To stat the directory obtained with C<aio_wd> above, one could write
1503	either of the following three request calls:	1653	either of the following three request calls:
1504		1654
1505	aio_lstat "/etc" , sub { ... # pathname as normal string	1655	aio_lstat "/etc" , sub { ... # pathname as normal string
…		…
1522	There are some caveats: when directories get renamed (or deleted), the	1672	There are some caveats: when directories get renamed (or deleted), the
1523	pathname string doesn't change, so will point to the new directory (or	1673	pathname string doesn't change, so will point to the new directory (or
1524	nowhere at all), while the directory fd, if available on the system,	1674	nowhere at all), while the directory fd, if available on the system,
1525	will still point to the original directory. Most functions accepting a	1675	will still point to the original directory. Most functions accepting a
1526	pathname will use the directory fd on newer systems, and the string on	1676	pathname will use the directory fd on newer systems, and the string on
1527	older systems. Some functions (such as realpath) will always rely on the	1677	older systems. Some functions (such as C<aio_realpath>) will always rely on
1528	string form of the pathname.	1678	the string form of the pathname.
1529		1679
1530	So this functionality is mainly useful to get some protection against	1680	So this functionality is mainly useful to get some protection against
1531	C<chdir>, to easily get an absolute path out of a relative path for future	1681	C<chdir>, to easily get an absolute path out of a relative path for future
1532	reference, and to speed up doing many operations in the same directory	1682	reference, and to speed up doing many operations in the same directory
1533	(e.g. when stat'ing all files in a directory).	1683	(e.g. when stat'ing all files in a directory).
…		…
1548	passing C<undef> as working directory component of a pathname fails the	1698	passing C<undef> as working directory component of a pathname fails the
1549	request with C<ENOENT>, there is often no need for error checking in the	1699	request with C<ENOENT>, there is often no need for error checking in the
1550	C<aio_wd> callback, as future requests using the value will fail in the	1700	C<aio_wd> callback, as future requests using the value will fail in the
1551	expected way.	1701	expected way.
1552		1702
1553	If this call isn't available because your OS lacks it or it couldn't be
1554	detected, it will be emulated by calling C<fsync> instead.
1555
1556	=item IO::AIO::CWD	1703	=item IO::AIO::CWD
1557		1704
1558	This is a compiletime constant (object) that represents the process	1705	This is a compile time constant (object) that represents the process
1559	current working directory.	1706	current working directory.
1560		1707
1561	Specifying this object as working directory object for a pathname is as if	1708	Specifying this object as working directory object for a pathname is as if
1562	the pathname would be specified directly, without a directory object. For	1709	the pathname would be specified directly, without a directory object. For
1563	example, these calls are functionally identical:	1710	example, these calls are functionally identical:
…		…
1572		1719
1573	aio_realpath $wd, sub {	1720	aio_realpath $wd, sub {
1574	warn "path is $_[0]\n";	1721	warn "path is $_[0]\n";
1575	};	1722	};
1576		1723
		1724	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1725	sometimes, fall back to using an absolue path.
1577		1726
1578	=head2 IO::AIO::REQ CLASS	1727	=head2 IO::AIO::REQ CLASS
1579		1728
1580	All non-aggregate C<aio_*> functions return an object of this class when	1729	All non-aggregate C<aio_*> functions return an object of this class when
1581	called in non-void context.	1730	called in non-void context.
…		…
1742	The default value for the limit is C<0>, but note that setting a feeder	1891	The default value for the limit is C<0>, but note that setting a feeder
1743	automatically bumps it up to C<2>.	1892	automatically bumps it up to C<2>.
1744		1893
1745	=back	1894	=back
1746		1895
		1896
1747	=head2 SUPPORT FUNCTIONS	1897	=head2 SUPPORT FUNCTIONS
1748		1898
1749	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1899	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1750		1900
1751	=over 4	1901	=over 4
…		…
1759		1909
1760	See C<poll_cb> for an example.	1910	See C<poll_cb> for an example.
1761		1911
1762	=item IO::AIO::poll_cb	1912	=item IO::AIO::poll_cb
1763		1913
1764	Process some outstanding events on the result pipe. You have to call	1914	Process some requests that have reached the result phase (i.e. they have
		1915	been executed but the results are not yet reported). You have to call
		1916	this "regularly" to finish outstanding requests.
		1917
1765	this regularly. Returns C<0> if all events could be processed (or there	1918	Returns C<0> if all events could be processed (or there were no
1766	were no events to process), or C<-1> if it returned earlier for whatever	1919	events to process), or C<-1> if it returned earlier for whatever
1767	reason. Returns immediately when no events are outstanding. The amount of	1920	reason. Returns immediately when no events are outstanding. The amount
1768	events processed depends on the settings of C<IO::AIO::max_poll_req> and	1921	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1769	C<IO::AIO::max_poll_time>.	1922	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1770		1923
1771	If not all requests were processed for whatever reason, the filehandle	1924	If not all requests were processed for whatever reason, the poll file
1772	will still be ready when C<poll_cb> returns, so normally you don't have to	1925	descriptor will still be ready when C<poll_cb> returns, so normally you
1773	do anything special to have it called later.	1926	don't have to do anything special to have it called later.
1774		1927
1775	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1928	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1776	ready, it can be beneficial to call this function from loops which submit	1929	ready, it can be beneficial to call this function from loops which submit
1777	a lot of requests, to make sure the results get processed when they become	1930	a lot of requests, to make sure the results get processed when they become
1778	available and not just when the loop is finished and the event loop takes	1931	available and not just when the loop is finished and the event loop takes
…		…
1787	poll => 'r', async => 1,	1940	poll => 'r', async => 1,
1788	cb => \&IO::AIO::poll_cb);	1941	cb => \&IO::AIO::poll_cb);
1789		1942
1790	=item IO::AIO::poll_wait	1943	=item IO::AIO::poll_wait
1791		1944
1792	If there are any outstanding requests and none of them in the result	1945	Wait until either at least one request is in the result phase or no
1793	phase, wait till the result filehandle becomes ready for reading (simply	1946	requests are outstanding anymore.
1794	does a C<select> on the filehandle. This is useful if you want to	1947
1795	synchronously wait for some requests to finish).	1948	This is useful if you want to synchronously wait for some requests to
		1949	become ready, without actually handling them.
1796		1950
1797	See C<nreqs> for an example.	1951	See C<nreqs> for an example.
1798		1952
1799	=item IO::AIO::poll	1953	=item IO::AIO::poll
1800		1954
…		…
1811		1965
1812	Strictly equivalent to:	1966	Strictly equivalent to:
1813		1967
1814	IO::AIO::poll_wait, IO::AIO::poll_cb	1968	IO::AIO::poll_wait, IO::AIO::poll_cb
1815	while IO::AIO::nreqs;	1969	while IO::AIO::nreqs;
		1970
		1971	This function can be useful at program aborts, to make sure outstanding
		1972	I/O has been done (C<IO::AIO> uses an C<END> block which already calls
		1973	this function on normal exits), or when you are merely using C<IO::AIO>
		1974	for its more advanced functions, rather than for async I/O, e.g.:
		1975
		1976	my ($dirs, $nondirs);
		1977	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1978	IO::AIO::flush;
		1979	# $dirs, $nondirs are now set
1816		1980
1817	=item IO::AIO::max_poll_reqs $nreqs	1981	=item IO::AIO::max_poll_reqs $nreqs
1818		1982
1819	=item IO::AIO::max_poll_time $seconds	1983	=item IO::AIO::max_poll_time $seconds
1820		1984
…		…
1847	poll => 'r', nice => 1,	2011	poll => 'r', nice => 1,
1848	cb => &IO::AIO::poll_cb);	2012	cb => &IO::AIO::poll_cb);
1849		2013
1850	=back	2014	=back
1851		2015
		2016
1852	=head3 CONTROLLING THE NUMBER OF THREADS	2017	=head3 CONTROLLING THE NUMBER OF THREADS
1853		2018
1854	=over	2019	=over
1855		2020
1856	=item IO::AIO::min_parallel $nthreads	2021	=item IO::AIO::min_parallel $nthreads
…		…
1917	longer exceeded.	2082	longer exceeded.
1918		2083
1919	In other words, this setting does not enforce a queue limit, but can be	2084	In other words, this setting does not enforce a queue limit, but can be
1920	used to make poll functions block if the limit is exceeded.	2085	used to make poll functions block if the limit is exceeded.
1921		2086
1922	This is a very bad function to use in interactive programs because it	2087	This is a bad function to use in interactive programs because it blocks,
1923	blocks, and a bad way to reduce concurrency because it is inexact: Better	2088	and a bad way to reduce concurrency because it is inexact. If you need to
		2089	issue many requests without being able to call a poll function on demand,
1924	use an C<aio_group> together with a feed callback.	2090	it is better to use an C<aio_group> together with a feed callback.
1925		2091
1926	It's main use is in scripts without an event loop - when you want to stat	2092	Its main use is in scripts without an event loop - when you want to stat a
1927	a lot of files, you can write somehting like this:	2093	lot of files, you can write something like this:
1928		2094
1929	IO::AIO::max_outstanding 32;	2095	IO::AIO::max_outstanding 32;
1930		2096
1931	for my $path (...) {	2097	for my $path (...) {
1932	aio_stat $path , ...;	2098	aio_stat $path , ...;
1933	IO::AIO::poll_cb;	2099	IO::AIO::poll_cb;
1934	}	2100	}
1935		2101
1936	IO::AIO::flush;	2102	IO::AIO::flush;
1937		2103
1938	The call to C<poll_cb> inside the loop will normally return instantly, but	2104	The call to C<poll_cb> inside the loop will normally return instantly,
1939	as soon as more thna C<32> reqeusts are in-flight, it will block until	2105	allowing the loop to progress, but as soon as more than C<32> requests
1940	some requests have been handled. This keeps the loop from pushing a large	2106	are in-flight, it will block until some requests have been handled. This
1941	number of C<aio_stat> requests onto the queue.	2107	keeps the loop from pushing a large number of C<aio_stat> requests onto
		2108	the queue (which, with many paths to stat, can use up a lot of memory).
1942		2109
1943	The default value for C<max_outstanding> is very large, so there is no	2110	The default value for C<max_outstanding> is very large, so there is no
1944	practical limit on the number of outstanding requests.	2111	practical limit on the number of outstanding requests.
1945		2112
1946	=back	2113	=back
1947		2114
		2115
1948	=head3 STATISTICAL INFORMATION	2116	=head3 STATISTICAL INFORMATION
1949		2117
1950	=over	2118	=over
1951		2119
1952	=item IO::AIO::nreqs	2120	=item IO::AIO::nreqs
…		…
1969	Returns the number of requests currently in the pending state (executed,	2137	Returns the number of requests currently in the pending state (executed,
1970	but not yet processed by poll_cb).	2138	but not yet processed by poll_cb).
1971		2139
1972	=back	2140	=back
1973		2141
		2142
		2143	=head3 SUBSECOND STAT TIME ACCESS
		2144
		2145	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2146	generally find access/modification and change times with subsecond time
		2147	accuracy of the system supports it, but perl's built-in functions only
		2148	return the integer part.
		2149
		2150	The following functions return the timestamps of the most recent
		2151	stat with subsecond precision on most systems and work both after
		2152	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2153	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2154	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2155
		2156	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2157	full resolution without rounding and work with standard perl C<stat>,
		2158	alleviating the need to call the special C<Time::HiRes> functions, which
		2159	do not act like their perl counterparts.
		2160
		2161	On operating systems or file systems where subsecond time resolution is
		2162	not supported or could not be detected, a fractional part of C<0> is
		2163	returned, so it is always safe to call these functions.
		2164
		2165	=over 4
		2166
		2167	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		2168
		2169	Return the access, modication, change or birth time, respectively,
		2170	including fractional part. Due to the limited precision of floating point,
		2171	the accuracy on most platforms is only a bit better than milliseconds
		2172	for times around now - see the I<nsec> function family, below, for full
		2173	accuracy.
		2174
		2175	File birth time is only available when the OS and perl support it (on
		2176	FreeBSD and NetBSD at the time of this writing, although support is
		2177	adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
		2178	it). On systems where it isn't available, C<0> is currently returned, but
		2179	this might change to C<undef> in a future version.
		2180
		2181	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		2182
		2183	Returns access, modification, change and birth time all in one go, and
		2184	maybe more times in the future version.
		2185
		2186	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		2187
		2188	Return the fractional access, modifcation, change or birth time, in nanoseconds,
		2189	as an integer in the range C<0> to C<999999999>.
		2190
		2191	Note that no accessors are provided for access, modification and
		2192	change times - you need to get those from C<stat _> if required (C<int
		2193	IO::AIO::st_atime> and so on will I<not> generally give you the correct
		2194	value).
		2195
		2196	=item $seconds = IO::AIO::st_btimesec
		2197
		2198	The (integral) seconds part of the file birth time, if available.
		2199
		2200	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		2201
		2202	Like the functions above, but returns all four times in one go (and maybe
		2203	more in future versions).
		2204
		2205	=item $counter = IO::AIO::st_gen
		2206
		2207	Returns the generation counter (in practice this is just a random number)
		2208	of the file. This is only available on platforms which have this member in
		2209	their C<struct stat> (most BSDs at the time of this writing) and generally
		2210	only to the root usert. If unsupported, C<0> is returned, but this might
		2211	change to C<undef> in a future version.
		2212
		2213	=back
		2214
		2215	Example: print the high resolution modification time of F</etc>, using
		2216	C<stat>, and C<IO::AIO::aio_stat>.
		2217
		2218	if (stat "/etc") {
		2219	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2220	}
		2221
		2222	IO::AIO::aio_stat "/etc", sub {
		2223	$_[0]
		2224	and return;
		2225
		2226	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2227	};
		2228
		2229	IO::AIO::flush;
		2230
		2231	Output of the awbove on my system, showing reduced and full accuracy:
		2232
		2233	stat(/etc) mtime: 1534043702.020808
		2234	aio_stat(/etc) mtime: 1534043702.020807792
		2235
		2236
1974	=head3 MISCELLANEOUS FUNCTIONS	2237	=head3 MISCELLANEOUS FUNCTIONS
1975		2238
1976	IO::AIO implements some functions that might be useful, but are not	2239	IO::AIO implements some functions that are useful when you want to use
1977	asynchronous.	2240	some "Advanced I/O" function not available to in Perl, without going the
		2241	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2242	counterpart.
1978		2243
1979	=over 4	2244	=over 4
		2245
		2246	=item $retval = IO::AIO::fexecve $fh, $argv, $envp
		2247
		2248	A more-or-less direct equivalent to the POSIX C<fexecve> functions, which
		2249	allows you to specify the program to be executed via a file descriptor (or
		2250	handle). Returns C<-1> and sets errno to C<ENOSYS> if not available.
		2251
		2252	=item $retval = IO::AIO::mount $special, $path, $fstype, $flags = 0, $data = undef
		2253
		2254	Calls the GNU/Linux mount syscall with the given arguments. All except
		2255	C<$flags> are strings, and if C<$data> is C<undef>, a C<NULL> will be
		2256	passed.
		2257
		2258	The following values for C<$flags> are available:
		2259
		2260	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>,
		2261	C<IO::AIO::MS_REMOUNT>, C<IO::AIO::MS_MANDLOCK>, C<IO::AIO::MS_DIRSYNC>, C<IO::AIO::MS_NOATIME>,
		2262	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>,
		2263	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>,
		2264	C<IO::AIO::MS_RELATIME>, C<IO::AIO::MS_KERNMOUNT>, C<IO::AIO::MS_I_VERSION>, C<IO::AIO::MS_STRICTATIME>,
		2265	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
		2266	C<IO::AIO::MS_MGC_MSK>.
		2267
		2268	=item $retval = IO::AIO::umount $path, $flags = 0
		2269
		2270	Invokes the GNU/Linux C<umount> or C<umount2> syscalls. Always calls
		2271	C<umount> if C<$flags> is C<0>, otherwqise always tries to call
		2272	C<umount2>.
		2273
		2274	The following C<$flags> are available:
		2275
		2276	C<IO::AIO::MNT_FORCE>, C<IO::AIO::MNT_DETACH>, C<IO::AIO::MNT_EXPIRE> and C<IO::AIO::UMOUNT_NOFOLLOW>.
		2277
		2278	=item $numfd = IO::AIO::get_fdlimit
		2279
		2280	Tries to find the current file descriptor limit and returns it, or
		2281	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2282	the highest valid file descriptor number.
		2283
		2284	=item IO::AIO::min_fdlimit [$numfd]
		2285
		2286	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2287	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2288	is missing, it will try to set a very high limit, although this is not
		2289	recommended when you know the actual minimum that you require.
		2290
		2291	If the limit cannot be raised enough, the function makes a best-effort
		2292	attempt to increase the limit as much as possible, using various
		2293	tricks, while still failing. You can query the resulting limit using
		2294	C<IO::AIO::get_fdlimit>.
		2295
		2296	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2297	true.
1980		2298
1981	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2299	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1982		2300
1983	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2301	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1984	but is blocking (this makes most sense if you know the input data is	2302	but is blocking (this makes most sense if you know the input data is
…		…
2001	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2319	=item IO::AIO::madvise $scalar, $offset, $len, $advice
2002		2320
2003	Simply calls the C<posix_madvise> function (see its	2321	Simply calls the C<posix_madvise> function (see its
2004	manpage for details). The following advice constants are	2322	manpage for details). The following advice constants are
2005	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2323	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
2006	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2324	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2325	C<IO::AIO::MADV_DONTNEED>.
		2326
		2327	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2328	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2329	will be reduced to fit into the C<$scalar>.
2007		2330
2008	On systems that do not implement C<posix_madvise>, this function returns	2331	On systems that do not implement C<posix_madvise>, this function returns
2009	ENOSYS, otherwise the return value of C<posix_madvise>.	2332	ENOSYS, otherwise the return value of C<posix_madvise>.
2010		2333
2011	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2334	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
…		…
2013	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2336	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
2014	$scalar (see its manpage for details). The following protect	2337	$scalar (see its manpage for details). The following protect
2015	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2338	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
2016	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2339	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
2017		2340
		2341	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2342	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2343	will be reduced to fit into the C<$scalar>.
		2344
2018	On systems that do not implement C<mprotect>, this function returns	2345	On systems that do not implement C<mprotect>, this function returns
2019	ENOSYS, otherwise the return value of C<mprotect>.	2346	ENOSYS, otherwise the return value of C<mprotect>.
2020		2347
2021	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2348	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
2022		2349
2023	Memory-maps a file (or anonymous memory range) and attaches it to the	2350	Memory-maps a file (or anonymous memory range) and attaches it to the
2024	given C<$scalar>, which will act like a string scalar. Returns true on	2351	given C<$scalar>, which will act like a string scalar. Returns true on
2025	success, and false otherwise.	2352	success, and false otherwise.
2026		2353
		2354	The scalar must exist, but its contents do not matter - this means you
		2355	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2356	the scalar first.
		2357
2027	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2358	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
2028	change the string length, and most read-only operations such as copying it	2359	which don't change the string length, and most read-only operations such
2029	or searching it with regexes and so on.	2360	as copying it or searching it with regexes and so on.
2030		2361
2031	Anything else is unsafe and will, at best, result in memory leaks.	2362	Anything else is unsafe and will, at best, result in memory leaks.
2032		2363
2033	The memory map associated with the C<$scalar> is automatically removed	2364	The memory map associated with the C<$scalar> is automatically removed
2034	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2365	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
2035	C<IO::AIO::munmap> functions are called.	2366	or C<IO::AIO::munmap> functions are called on it.
2036		2367
2037	This calls the C<mmap>(2) function internally. See your system's manual	2368	This calls the C<mmap>(2) function internally. See your system's manual
2038	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2369	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
2039		2370
2040	The C<$length> must be larger than zero and smaller than the actual	2371	The C<$length> must be larger than zero and smaller than the actual
2041	filesize.	2372	filesize.
2042		2373
2043	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2374	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
2044	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2375	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
2045		2376
2046	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2377	C<$flags> can be a combination of
2047	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2378	C<IO::AIO::MAP_SHARED> or
2048	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2379	C<IO::AIO::MAP_PRIVATE>,
		2380	or a number of system-specific flags (when not available, the are C<0>):
2049	(which is set to C<MAP_ANON> if your system only provides this	2381	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
2050	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2382	C<IO::AIO::MAP_LOCKED>,
2051	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2383	C<IO::AIO::MAP_NORESERVE>,
		2384	C<IO::AIO::MAP_POPULATE>,
2052	C<IO::AIO::MAP_NONBLOCK>	2385	C<IO::AIO::MAP_NONBLOCK>,
		2386	C<IO::AIO::MAP_FIXED>,
		2387	C<IO::AIO::MAP_GROWSDOWN>,
		2388	C<IO::AIO::MAP_32BIT>,
		2389	C<IO::AIO::MAP_HUGETLB>,
		2390	C<IO::AIO::MAP_STACK>,
		2391	C<IO::AIO::MAP_FIXED_NOREPLACE>,
		2392	C<IO::AIO::MAP_SHARED_VALIDATE>,
		2393	C<IO::AIO::MAP_SYNC> or
		2394	C<IO::AIO::MAP_UNINITIALIZED>.
2053		2395
2054	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2396	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
2055		2397
2056	C<$offset> is the offset from the start of the file - it generally must be	2398	C<$offset> is the offset from the start of the file - it generally must be
2057	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2399	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
2071		2413
2072	=item IO::AIO::munmap $scalar	2414	=item IO::AIO::munmap $scalar
2073		2415
2074	Removes a previous mmap and undefines the C<$scalar>.	2416	Removes a previous mmap and undefines the C<$scalar>.
2075		2417
		2418	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2419
		2420	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2421	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2422	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2423
		2424	Returns true if successful, and false otherwise. If the underlying mmapped
		2425	region has changed address, then the true value has the numerical value
		2426	C<1>, otherwise it has the numerical value C<0>:
		2427
		2428	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2429	or die "mremap: $!";
		2430
		2431	if ($success*1) {
		2432	warn "scalar has chanegd address in memory\n";
		2433	}
		2434
		2435	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2436	implemented, but not supported and might go away in a future version.
		2437
		2438	On systems where this call is not supported or is not emulated, this call
		2439	returns falls and sets C<$!> to C<ENOSYS>.
		2440
		2441	=item IO::AIO::mlockall $flags
		2442
		2443	Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
		2444	but is blocking.
		2445
2076	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef	2446	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
2077		2447
2078	Calls the C<munlock> function, undoing the effects of a previous	2448	Calls the C<munlock> function, undoing the effects of a previous
2079	C<aio_mlock> call (see its description for details).	2449	C<aio_mlock> call (see its description for details).
2080		2450
…		…
2082		2452
2083	Calls the C<munlockall> function.	2453	Calls the C<munlockall> function.
2084		2454
2085	On systems that do not implement C<munlockall>, this function returns	2455	On systems that do not implement C<munlockall>, this function returns
2086	ENOSYS, otherwise the return value of C<munlockall>.	2456	ENOSYS, otherwise the return value of C<munlockall>.
		2457
		2458	=item $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		2459
		2460	Uses the GNU/Linux C<accept4(2)> syscall, if available, to accept a socket
		2461	and return the new file handle on success, or sets C<$!> and returns
		2462	C<undef> on error.
		2463
		2464	The remote name of the new socket will be stored in C<$sockaddr>, which
		2465	will be extended to allow for at least C<$sockaddr_maxlen> octets. If the
		2466	socket name does not fit into C<$sockaddr_maxlen> octets, this is signaled
		2467	by returning a longer string in C<$sockaddr>, which might or might not be
		2468	truncated.
		2469
		2470	To accept name-less sockets, use C<undef> for C<$sockaddr> and C<0> for
		2471	C<$sockaddr_maxlen>.
		2472
		2473	The main reasons to use this syscall rather than portable C<accept(2)>
		2474	are that you can specify C<SOCK_NONBLOCK> and/or C<SOCK_CLOEXEC>
		2475	flags and you can accept name-less sockets by specifying C<0> for
		2476	C<$sockaddr_maxlen>, which is sadly not possible with perl's interface to
		2477	C<accept>.
2087		2478
2088	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags	2479	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
2089		2480
2090	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or	2481	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
2091	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they	2482	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
…		…
2100		2491
2101	See the C<splice(2)> manpage for details.	2492	See the C<splice(2)> manpage for details.
2102		2493
2103	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags	2494	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
2104		2495
2105	Calls the GNU/Linux C<tee(2)> syscall, see it's manpage and the	2496	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
2106	description for C<IO::AIO::splice> above for details.	2497	description for C<IO::AIO::splice> above for details.
		2498
		2499	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2500
		2501	Attempts to query or change the pipe buffer size. Obviously works only
		2502	on pipes, and currently works only on GNU/Linux systems, and fails with
		2503	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2504	size on other systems, drop me a note.
		2505
		2506	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2507
		2508	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2509	C<$flags> is missing or C<0>, then this should be the same as a call to
		2510	perl's built-in C<pipe> function and create a new pipe, and works on
		2511	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2512	(..., 4096, O_BINARY)>.
		2513
		2514	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2515	the given flags (Linux 2.6.27, glibc 2.9).
		2516
		2517	On success, the read and write file handles are returned.
		2518
		2519	On error, nothing will be returned. If the pipe2 syscall is missing and
		2520	C<$flags> is non-zero, fails with C<ENOSYS>.
		2521
		2522	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2523	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2524	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2525
		2526	Example: create a pipe race-free w.r.t. threads and fork:
		2527
		2528	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2529	or die "pipe2: $!\n";
		2530
		2531	=item $fh = IO::AIO::memfd_create $pathname[, $flags]
		2532
		2533	This is a direct interface to the Linux L<memfd_create(2)> system
		2534	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2535	should be C<IO::AIO::MFD_CLOEXEC>.
		2536
		2537	On success, the new memfd filehandle is returned, otherwise returns
		2538	C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
		2539
		2540	Please refer to L<memfd_create(2)> for more info on this call.
		2541
		2542	The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
		2543	C<IO::AIO::MFD_ALLOW_SEALING>, C<IO::AIO::MFD_HUGETLB>,
		2544	C<IO::AIO::MFD_HUGETLB_2MB> and C<IO::AIO::MFD_HUGETLB_1GB>.
		2545
		2546	Example: create a new memfd.
		2547
		2548	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2549	or die "memfd_create: $!\n";
		2550
		2551	=item $fh = IO::AIO::pidfd_open $pid[, $flags]
		2552
		2553	This is an interface to the Linux L<pidfd_open(2)> system call. The
		2554	default for C<$flags> is C<0>.
		2555
		2556	On success, a new pidfd filehandle is returned (that is already set to
		2557	close-on-exec), otherwise returns C<undef>. If the syscall is missing,
		2558	fails with C<ENOSYS>.
		2559
		2560	Example: open pid 6341 as pidfd.
		2561
		2562	my $fh = IO::AIO::pidfd_open 6341
		2563	or die "pidfd_open: $!\n";
		2564
		2565	=item $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		2566
		2567	This is an interface to the Linux L<pidfd_send_signal> system call. The
		2568	default for C<$siginfo> is C<undef> and the default for C<$flags> is C<0>.
		2569
		2570	Returns the system call status. If the syscall is missing, fails with
		2571	C<ENOSYS>.
		2572
		2573	When specified, C<$siginfo> must be a reference to a hash with one or more
		2574	of the following members:
		2575
		2576	=over
		2577
		2578	=item code - the C<si_code> member
		2579
		2580	=item pid - the C<si_pid> member
		2581
		2582	=item uid - the C<si_uid> member
		2583
		2584	=item value_int - the C<si_value.sival_int> member
		2585
		2586	=item value_ptr - the C<si_value.sival_ptr> member, specified as an integer
		2587
		2588	=back
		2589
		2590	Example: send a SIGKILL to the specified process.
		2591
		2592	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
		2593	and die "pidfd_send_signal: $!\n";
		2594
		2595	Example: send a SIGKILL to the specified process with extra data.
		2596
		2597	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
		2598	and die "pidfd_send_signal: $!\n";
		2599
		2600	=item $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		2601
		2602	This is an interface to the Linux L<pidfd_getfd> system call. The default
		2603	for C<$flags> is C<0>.
		2604
		2605	On success, returns a dup'ed copy of the target file descriptor (specified
		2606	as an integer) returned (that is already set to close-on-exec), otherwise
		2607	returns C<undef>. If the syscall is missing, fails with C<ENOSYS>.
		2608
		2609	Example: get a copy of standard error of another process and print soemthing to it.
		2610
		2611	my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
		2612	or die "pidfd_getfd: $!\n";
		2613	print $errfh "stderr\n";
		2614
		2615	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2616
		2617	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2618	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2619
		2620	On success, the new eventfd filehandle is returned, otherwise returns
		2621	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2622
		2623	Please refer to L<eventfd(2)> for more info on this call.
		2624
		2625	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2626	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2627
		2628	Example: create a new eventfd filehandle:
		2629
		2630	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2631	or die "eventfd: $!\n";
		2632
		2633	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2634
		2635	This is a direct interface to the Linux L<timerfd_create(2)> system
		2636	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2637	should be C<IO::AIO::TFD_CLOEXEC>.
		2638
		2639	On success, the new timerfd filehandle is returned, otherwise returns
		2640	C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
		2641
		2642	Please refer to L<timerfd_create(2)> for more info on this call.
		2643
		2644	The following C<$clockid> values are
		2645	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2646	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2647	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2648	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2649
		2650	The following C<$flags> values are available (Linux
		2651	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2652
		2653	Example: create a new timerfd and set it to one-second repeated alarms,
		2654	then wait for two alarms:
		2655
		2656	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2657	or die "timerfd_create: $!\n";
		2658
		2659	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2660	or die "timerfd_settime: $!\n";
		2661
		2662	for (1..2) {
		2663	8 == sysread $fh, my $buf, 8
		2664	or die "timerfd read failure\n";
		2665
		2666	printf "number of expirations (likely 1): %d\n",
		2667	unpack "Q", $buf;
		2668	}
		2669
		2670	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2671
		2672	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2673	call. Please refer to its manpage for more info on this call.
		2674
		2675	The new itimerspec is specified using two (possibly fractional) second
		2676	values, C<$new_interval> and C<$new_value>).
		2677
		2678	On success, the current interval and value are returned (as per
		2679	C<timerfd_gettime>). On failure, the empty list is returned.
		2680
		2681	The following C<$flags> values are
		2682	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2683	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2684
		2685	See C<IO::AIO::timerfd_create> for a full example.
		2686
		2687	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2688
		2689	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2690	call. Please refer to its manpage for more info on this call.
		2691
		2692	On success, returns the current values of interval and value for the given
		2693	timerfd (as potentially fractional second values). On failure, the empty
		2694	list is returned.
2107		2695
2108	=back	2696	=back
2109		2697
2110	=cut	2698	=cut
2111		2699
…		…
2177	the process will result in undefined behaviour. Calling it at any time	2765	the process will result in undefined behaviour. Calling it at any time
2178	will also result in any undefined (by POSIX) behaviour.	2766	will also result in any undefined (by POSIX) behaviour.
2179		2767
2180	=back	2768	=back
2181		2769
		2770	=head2 LINUX-SPECIFIC CALLS
		2771
		2772	When a call is documented as "linux-specific" then this means it
		2773	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2774	availability and compatibility of such calls regardless of the platform
		2775	it is compiled on, so platforms such as FreeBSD which often implement
		2776	these calls will work. When in doubt, call them and see if they fail wth
		2777	C<ENOSYS>.
		2778
2182	=head2 MEMORY USAGE	2779	=head2 MEMORY USAGE
2183		2780
2184	Per-request usage:	2781	Per-request usage:
2185		2782
2186	Each aio request uses - depending on your architecture - around 100-200	2783	Each aio request uses - depending on your architecture - around 100-200
…		…
2198	temporary buffers, and each thread requires a stack and other data	2795	temporary buffers, and each thread requires a stack and other data
2199	structures (usually around 16k-128k, depending on the OS).	2796	structures (usually around 16k-128k, depending on the OS).
2200		2797
2201	=head1 KNOWN BUGS	2798	=head1 KNOWN BUGS
2202		2799
2203	Known bugs will be fixed in the next release.	2800	Known bugs will be fixed in the next release :)
		2801
		2802	=head1 KNOWN ISSUES
		2803
		2804	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2805	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2806	non-created hash slots or other scalars I didn't think of. It's best to
		2807	avoid such and either use scalar variables or making sure that the scalar
		2808	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2809
		2810	I am not sure anything can be done about this, so this is considered a
		2811	known issue, rather than a bug.
2204		2812
2205	=head1 SEE ALSO	2813	=head1 SEE ALSO
2206		2814
2207	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2815	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
2208	more natural syntax.	2816	more natural syntax and L<IO::FDPass> for file descriptor passing.
2209		2817
2210	=head1 AUTHOR	2818	=head1 AUTHOR
2211		2819
2212	Marc Lehmann <schmorp@schmorp.de>	2820	Marc Lehmann <schmorp@schmorp.de>
2213	http://home.schmorp.de/	2821	http://home.schmorp.de/

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