[ViewVC] Diff of: cvs/IO-AIO/README

Comparing IO-AIO/README (file contents):
Revision 1.53 by root, Thu Oct 11 03:20:52 2012 UTC vs.
Revision 1.66 by root, Tue Dec 29 15:20:12 2020 UTC

…		…
1	NAME	1	NAME
2	IO::AIO - Asynchronous Input/Output	2	IO::AIO - Asynchronous/Advanced Input/Output
3		3
4	SYNOPSIS	4	SYNOPSIS
5	use IO::AIO;	5	use IO::AIO;
6		6
7	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {	7	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
55	not well-supported or restricted (GNU/Linux doesn't allow them on normal	55	not well-supported or restricted (GNU/Linux doesn't allow them on normal
56	files currently, for example), and they would only support aio_read and	56	files currently, for example), and they would only support aio_read and
57	aio_write, so the remaining functionality would have to be implemented	57	aio_write, so the remaining functionality would have to be implemented
58	using threads anyway.	58	using threads anyway.
59		59
		60	In addition to asynchronous I/O, this module also exports some rather
		61	arcane interfaces, such as "madvise" or linux's "splice" system call,
		62	which is why the "A" in "AIO" can also mean advanced.
		63
60	Although the module will work in the presence of other (Perl-) threads,	64	Although the module will work in the presence of other (Perl-) threads,
61	it is currently not reentrant in any way, so use appropriate locking	65	it is currently not reentrant in any way, so use appropriate locking
62	yourself, always call "poll_cb" from within the same thread, or never	66	yourself, always call "poll_cb" from within the same thread, or never
63	call "poll_cb" (or other "aio_" functions) recursively.	67	call "poll_cb" (or other "aio_" functions) recursively.
64		68
65	EXAMPLE	69	EXAMPLE
66	This is a simple example that uses the EV module and loads /etc/passwd	70	This is a simple example that uses the EV module and loads /etc/passwd
67	asynchronously:	71	asynchronously:
68		72
69	use Fcntl;
70	use EV;	73	use EV;
71	use IO::AIO;	74	use IO::AIO;
72		75
73	# register the IO::AIO callback with EV	76	# register the IO::AIO callback with EV
74	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	77	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
…		…
91		94
92	# file contents now in $contents	95	# file contents now in $contents
93	print $contents;	96	print $contents;
94		97
95	# exit event loop and program	98	# exit event loop and program
96	EV::unloop;	99	EV::break;
97	};	100	};
98	};	101	};
99		102
100	# possibly queue up other requests, or open GUI windows,	103	# possibly queue up other requests, or open GUI windows,
101	# check for sockets etc. etc.	104	# check for sockets etc. etc.
102		105
103	# process events as long as there are some:	106	# process events as long as there are some:
104	EV::loop;	107	EV::run;
105		108
106	REQUEST ANATOMY AND LIFETIME	109	REQUEST ANATOMY AND LIFETIME
107	Every "aio_*" function creates a request. which is a C data structure	110	Every "aio_*" function creates a request. which is a C data structure
108	not directly visible to Perl.	111	not directly visible to Perl.
109		112
…		…
172	aio_unlink $pathname, $callback->($status)	175	aio_unlink $pathname, $callback->($status)
173	aio_mknod $pathname, $mode, $dev, $callback->($status)	176	aio_mknod $pathname, $mode, $dev, $callback->($status)
174	aio_link $srcpath, $dstpath, $callback->($status)	177	aio_link $srcpath, $dstpath, $callback->($status)
175	aio_symlink $srcpath, $dstpath, $callback->($status)	178	aio_symlink $srcpath, $dstpath, $callback->($status)
176	aio_readlink $pathname, $callback->($link)	179	aio_readlink $pathname, $callback->($link)
177	aio_realpath $pathname, $callback->($link)	180	aio_realpath $pathname, $callback->($path)
178	aio_rename $srcpath, $dstpath, $callback->($status)	181	aio_rename $srcpath, $dstpath, $callback->($status)
		182	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
179	aio_mkdir $pathname, $mode, $callback->($status)	183	aio_mkdir $pathname, $mode, $callback->($status)
180	aio_rmdir $pathname, $callback->($status)	184	aio_rmdir $pathname, $callback->($status)
181	aio_readdir $pathname, $callback->($entries)	185	aio_readdir $pathname, $callback->($entries)
182	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	186	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
183	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	187	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
…		…
185	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)	189	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
186	aio_load $pathname, $data, $callback->($status)	190	aio_load $pathname, $data, $callback->($status)
187	aio_copy $srcpath, $dstpath, $callback->($status)	191	aio_copy $srcpath, $dstpath, $callback->($status)
188	aio_move $srcpath, $dstpath, $callback->($status)	192	aio_move $srcpath, $dstpath, $callback->($status)
189	aio_rmtree $pathname, $callback->($status)	193	aio_rmtree $pathname, $callback->($status)
		194	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		195	aio_ioctl $fh, $request, $buf, $callback->($status)
190	aio_sync $callback->($status)	196	aio_sync $callback->($status)
191	aio_syncfs $fh, $callback->($status)	197	aio_syncfs $fh, $callback->($status)
192	aio_fsync $fh, $callback->($status)	198	aio_fsync $fh, $callback->($status)
193	aio_fdatasync $fh, $callback->($status)	199	aio_fdatasync $fh, $callback->($status)
194	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	200	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
195	aio_pathsync $pathname, $callback->($status)	201	aio_pathsync $pathname, $callback->($status)
196	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	202	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
197	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	203	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
198	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	204	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
199	aio_mlockall $flags, $callback->($status)	205	aio_mlockall $flags, $callback->($status)
200	aio_group $callback->(...)	206	aio_group $callback->(...)
201	aio_nop $callback->()	207	aio_nop $callback->()
…		…
215	IO::AIO::idle_timeout $seconds	221	IO::AIO::idle_timeout $seconds
216	IO::AIO::max_outstanding $maxreqs	222	IO::AIO::max_outstanding $maxreqs
217	IO::AIO::nreqs	223	IO::AIO::nreqs
218	IO::AIO::nready	224	IO::AIO::nready
219	IO::AIO::npending	225	IO::AIO::npending
		226	IO::AIO::reinit
		227
		228	$nfd = IO::AIO::get_fdlimit
		229	IO::AIO::min_fdlimit $nfd
220		230
221	IO::AIO::sendfile $ofh, $ifh, $offset, $count	231	IO::AIO::sendfile $ofh, $ifh, $offset, $count
222	IO::AIO::fadvise $fh, $offset, $len, $advice	232	IO::AIO::fadvise $fh, $offset, $len, $advice
		233
223	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]	234	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
224	IO::AIO::munmap $scalar	235	IO::AIO::munmap $scalar
		236	IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
225	IO::AIO::madvise $scalar, $offset, $length, $advice	237	IO::AIO::madvise $scalar, $offset, $length, $advice
226	IO::AIO::mprotect $scalar, $offset, $length, $protect	238	IO::AIO::mprotect $scalar, $offset, $length, $protect
227	IO::AIO::munlock $scalar, $offset = 0, $length = undef	239	IO::AIO::munlock $scalar, $offset = 0, $length = undef
228	IO::AIO::munlockall	240	IO::AIO::munlockall
		241
		242	# stat extensions
		243	$counter = IO::AIO::st_gen
		244	$seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		245	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		246	$nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		247	$seconds = IO::AIO::st_btimesec
		248	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		249
		250	# very much unportable syscalls
		251	IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
		252	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		253	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		254	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		255	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		256	$fh = IO::AIO::memfd_create $pathname[, $flags]
		257	$fh = IO::AIO::eventfd [$initval, [$flags]]
		258	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		259	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		260	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
229		261
230	API NOTES	262	API NOTES
231	All the "aio_*" calls are more or less thin wrappers around the syscall	263	All the "aio_*" calls are more or less thin wrappers around the syscall
232	with the same name (sans "aio_"). The arguments are similar or	264	with the same name (sans "aio_"). The arguments are similar or
233	identical, and they all accept an additional (and optional) $callback	265	identical, and they all accept an additional (and optional) $callback
…		…
331	"O_APPEND"), the following POSIX and non-POSIX constants are	363	"O_APPEND"), the following POSIX and non-POSIX constants are
332	available (missing ones on your system are, as usual, 0):	364	available (missing ones on your system are, as usual, 0):
333		365
334	"O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",	366	"O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
335	"O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",	367	"O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
336	"O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT".	368	"O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", "O_TTY_INIT"
		369	and "O_ACCMODE".
337		370
338	aio_close $fh, $callback->($status)	371	aio_close $fh, $callback->($status)
339	Asynchronously close a file and call the callback with the result	372	Asynchronously close a file and call the callback with the result
340	code.	373	code.
341		374
…		…
371		404
372	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	405	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
373	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	406	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
374	Reads or writes $length bytes from or to the specified $fh and	407	Reads or writes $length bytes from or to the specified $fh and
375	$offset into the scalar given by $data and offset $dataoffset and	408	$offset into the scalar given by $data and offset $dataoffset and
376	calls the callback without the actual number of bytes read (or -1 on	409	calls the callback with the actual number of bytes transferred (or
377	error, just like the syscall).	410	-1 on error, just like the syscall).
378		411
379	"aio_read" will, like "sysread", shrink or grow the $data scalar to	412	"aio_read" will, like "sysread", shrink or grow the $data scalar to
380	offset plus the actual number of bytes read.	413	offset plus the actual number of bytes read.
381		414
382	If $offset is undefined, then the current file descriptor offset	415	If $offset is undefined, then the current file descriptor offset
…		…
439	As native sendfile syscalls (as practically any non-POSIX interface	472	As native sendfile syscalls (as practically any non-POSIX interface
440	hacked together in a hurry to improve benchmark numbers) tend to be	473	hacked together in a hurry to improve benchmark numbers) tend to be
441	rather buggy on many systems, this implementation tries to work	474	rather buggy on many systems, this implementation tries to work
442	around some known bugs in Linux and FreeBSD kernels (probably	475	around some known bugs in Linux and FreeBSD kernels (probably
443	others, too), but that might fail, so you really really should check	476	others, too), but that might fail, so you really really should check
444	the return value of "aio_sendfile" - fewre bytes than expected might	477	the return value of "aio_sendfile" - fewer bytes than expected might
445	have been transferred.	478	have been transferred.
446		479
447	aio_readahead $fh,$offset,$length, $callback->($retval)	480	aio_readahead $fh,$offset,$length, $callback->($retval)
448	"aio_readahead" populates the page cache with data from a file so	481	"aio_readahead" populates the page cache with data from a file so
449	that subsequent reads from that file will not block on disk I/O. The	482	that subsequent reads from that file will not block on disk I/O. The
…		…
453	to a page boundary and bytes are read up to the next page boundary	486	to a page boundary and bytes are read up to the next page boundary
454	greater than or equal to (off-set+length). "aio_readahead" does not	487	greater than or equal to (off-set+length). "aio_readahead" does not
455	read beyond the end of the file. The current file offset of the file	488	read beyond the end of the file. The current file offset of the file
456	is left unchanged.	489	is left unchanged.
457		490
458	If that syscall doesn't exist (likely if your OS isn't Linux) it	491	If that syscall doesn't exist (likely if your kernel isn't Linux) it
459	will be emulated by simply reading the data, which would have a	492	will be emulated by simply reading the data, which would have a
460	similar effect.	493	similar effect.
461		494
462	aio_stat $fh_or_path, $callback->($status)	495	aio_stat $fh_or_path, $callback->($status)
463	aio_lstat $fh, $callback->($status)	496	aio_lstat $fh, $callback->($status)
464	Works like perl's "stat" or "lstat" in void context. The callback	497	Works almost exactly like perl's "stat" or "lstat" in void context.
465	will be called after the stat and the results will be available	498	The callback will be called after the stat and the results will be
466	using "stat _" or "-s _" etc...	499	available using "stat _" or "-s _" and other tests (with the
		500	exception of "-B" and "-T").
467		501
468	The pathname passed to "aio_stat" must be absolute. See API NOTES,	502	The pathname passed to "aio_stat" must be absolute. See API NOTES,
469	above, for an explanation.	503	above, for an explanation.
470		504
471	Currently, the stats are always 64-bit-stats, i.e. instead of	505	Currently, the stats are always 64-bit-stats, i.e. instead of
…		…
479	back on traditional behaviour).	513	back on traditional behaviour).
480		514
481	"S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",	515	"S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
482	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",	516	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
483	"IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".	517	"IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
		518
		519	To access higher resolution stat timestamps, see "SUBSECOND STAT
		520	TIME ACCESS".
484		521
485	Example: Print the length of /etc/passwd:	522	Example: Print the length of /etc/passwd:
486		523
487	aio_stat "/etc/passwd", sub {	524	aio_stat "/etc/passwd", sub {
488	$_[0] and die "stat failed: $!";	525	$_[0] and die "stat failed: $!";
…		…
530	namemax => 255,	567	namemax => 255,
531	frsize => 1024,	568	frsize => 1024,
532	fsid => 1810	569	fsid => 1810
533	}	570	}
534		571
535	Here is a (likely partial) list of fsid values used by Linux - it is
536	safe to hardcode these when the $^O is "linux":
537
538	0x0000adf5 adfs
539	0x0000adff affs
540	0x5346414f afs
541	0x09041934 anon-inode filesystem
542	0x00000187 autofs
543	0x42465331 befs
544	0x1badface bfs
545	0x42494e4d binfmt_misc
546	0x9123683e btrfs
547	0x0027e0eb cgroupfs
548	0xff534d42 cifs
549	0x73757245 coda
550	0x012ff7b7 coh
551	0x28cd3d45 cramfs
552	0x453dcd28 cramfs-wend (wrong endianness)
553	0x64626720 debugfs
554	0x00001373 devfs
555	0x00001cd1 devpts
556	0x0000f15f ecryptfs
557	0x00414a53 efs
558	0x0000137d ext
559	0x0000ef53 ext2/ext3
560	0x0000ef51 ext2
561	0x00004006 fat
562	0x65735546 fuseblk
563	0x65735543 fusectl
564	0x0bad1dea futexfs
565	0x01161970 gfs2
566	0x47504653 gpfs
567	0x00004244 hfs
568	0xf995e849 hpfs
569	0x958458f6 hugetlbfs
570	0x2bad1dea inotifyfs
571	0x00009660 isofs
572	0x000072b6 jffs2
573	0x3153464a jfs
574	0x6b414653 k-afs
575	0x0bd00bd0 lustre
576	0x0000137f minix
577	0x0000138f minix 30 char names
578	0x00002468 minix v2
579	0x00002478 minix v2 30 char names
580	0x00004d5a minix v3
581	0x19800202 mqueue
582	0x00004d44 msdos
583	0x0000564c novell
584	0x00006969 nfs
585	0x6e667364 nfsd
586	0x00003434 nilfs
587	0x5346544e ntfs
588	0x00009fa1 openprom
589	0x7461636F ocfs2
590	0x00009fa0 proc
591	0x6165676c pstorefs
592	0x0000002f qnx4
593	0x858458f6 ramfs
594	0x52654973 reiserfs
595	0x00007275 romfs
596	0x67596969 rpc_pipefs
597	0x73636673 securityfs
598	0xf97cff8c selinux
599	0x0000517b smb
600	0x534f434b sockfs
601	0x73717368 squashfs
602	0x62656572 sysfs
603	0x012ff7b6 sysv2
604	0x012ff7b5 sysv4
605	0x01021994 tmpfs
606	0x15013346 udf
607	0x00011954 ufs
608	0x54190100 ufs byteswapped
609	0x00009fa2 usbdevfs
610	0x01021997 v9fs
611	0xa501fcf5 vxfs
612	0xabba1974 xenfs
613	0x012ff7b4 xenix
614	0x58465342 xfs
615	0x012fd16d xia
616
617	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	572	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
618	Works like perl's "utime" function (including the special case of	573	Works like perl's "utime" function (including the special case of
619	$atime and $mtime being undef). Fractional times are supported if	574	$atime and $mtime being undef). Fractional times are supported if
620	the underlying syscalls support them.	575	the underlying syscalls support them.
621		576
622	When called with a pathname, uses utimes(2) if available, otherwise	577	When called with a pathname, uses utimensat(2) or utimes(2) if
623	utime(2). If called on a file descriptor, uses futimes(2) if	578	available, otherwise utime(2). If called on a file descriptor, uses
624	available, otherwise returns ENOSYS, so this is not portable.	579	futimens(2) or futimes(2) if available, otherwise returns ENOSYS, so
		580	this is not portable.
625		581
626	Examples:	582	Examples:
627		583
628	# set atime and mtime to current time (basically touch(1)):	584	# set atime and mtime to current time (basically touch(1)):
629	aio_utime "path", undef, undef;	585	aio_utime "path", undef, undef;
…		…
644		600
645	aio_truncate $fh_or_path, $offset, $callback->($status)	601	aio_truncate $fh_or_path, $offset, $callback->($status)
646	Works like truncate(2) or ftruncate(2).	602	Works like truncate(2) or ftruncate(2).
647		603
648	aio_allocate $fh, $mode, $offset, $len, $callback->($status)	604	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
649	Allocates or freed disk space according to the $mode argument. See	605	Allocates or frees disk space according to the $mode argument. See
650	the linux "fallocate" docuemntation for details.	606	the linux "fallocate" documentation for details.
651		607
652	$mode can currently be 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to	608	$mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
653	allocate space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE \|	609	space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE \|
654	IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.	610	IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
655		611
		612	IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range
		613	(without leaving a hole), "FALLOC_FL_ZERO_RANGE", to zero a range,
		614	"FALLOC_FL_INSERT_RANGE" to insert a range and
		615	"FALLOC_FL_UNSHARE_RANGE" to unshare shared blocks (see your
		616	fallocate(2) manpage).
		617
656	The file system block size used by "fallocate" is presumably the	618	The file system block size used by "fallocate" is presumably the
657	"f_bsize" returned by "statvfs".	619	"f_bsize" returned by "statvfs", but different filesystems and
		620	filetypes can dictate other limitations.
658		621
659	If "fallocate" isn't available or cannot be emulated (currently no	622	If "fallocate" isn't available or cannot be emulated (currently no
660	emulation will be attempted), passes -1 and sets $! to "ENOSYS".	623	emulation will be attempted), passes -1 and sets $! to "ENOSYS".
661		624
662	aio_chmod $fh_or_path, $mode, $callback->($status)	625	aio_chmod $fh_or_path, $mode, $callback->($status)
…		…
692	the callback. If an error occurs, nothing or undef gets passed to	655	the callback. If an error occurs, nothing or undef gets passed to
693	the callback.	656	the callback.
694		657
695	aio_realpath $pathname, $callback->($path)	658	aio_realpath $pathname, $callback->($path)
696	Asynchronously make the path absolute and resolve any symlinks in	659	Asynchronously make the path absolute and resolve any symlinks in
697	$path. The resulting path only consists of directories (Same as	660	$path. The resulting path only consists of directories (same as
698	Cwd::realpath).	661	Cwd::realpath).
699		662
700	This request can be used to get the absolute path of the current	663	This request can be used to get the absolute path of the current
701	working directory by passing it a path of . (a single dot).	664	working directory by passing it a path of . (a single dot).
702		665
703	aio_rename $srcpath, $dstpath, $callback->($status)	666	aio_rename $srcpath, $dstpath, $callback->($status)
704	Asynchronously rename the object at $srcpath to $dstpath, just as	667	Asynchronously rename the object at $srcpath to $dstpath, just as
705	rename(2) and call the callback with the result code.	668	rename(2) and call the callback with the result code.
		669
		670	On systems that support the AIO::WD working directory abstraction
		671	natively, the case "[$wd, "."]" as $srcpath is specialcased -
		672	instead of failing, "rename" is called on the absolute path of $wd.
		673
		674	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		675	Basically a version of "aio_rename" with an additional $flags
		676	argument. Calling this with "$flags=0" is the same as calling
		677	"aio_rename".
		678
		679	Non-zero flags are currently only supported on GNU/Linux systems
		680	that support renameat2. Other systems fail with "ENOSYS" in this
		681	case.
		682
		683	The following constants are available (missing ones are, as usual
		684	0), see renameat2(2) for details:
		685
		686	"IO::AIO::RENAME_NOREPLACE", "IO::AIO::RENAME_EXCHANGE" and
		687	"IO::AIO::RENAME_WHITEOUT".
706		688
707	aio_mkdir $pathname, $mode, $callback->($status)	689	aio_mkdir $pathname, $mode, $callback->($status)
708	Asynchronously mkdir (create) a directory and call the callback with	690	Asynchronously mkdir (create) a directory and call the callback with
709	the result code. $mode will be modified by the umask at the time the	691	the result code. $mode will be modified by the umask at the time the
710	request is executed, so do not change your umask.	692	request is executed, so do not change your umask.
711		693
712	aio_rmdir $pathname, $callback->($status)	694	aio_rmdir $pathname, $callback->($status)
713	Asynchronously rmdir (delete) a directory and call the callback with	695	Asynchronously rmdir (delete) a directory and call the callback with
714	the result code.	696	the result code.
715		697
		698	On systems that support the AIO::WD working directory abstraction
		699	natively, the case "[$wd, "."]" is specialcased - instead of
		700	failing, "rmdir" is called on the absolute path of $wd.
		701
716	aio_readdir $pathname, $callback->($entries)	702	aio_readdir $pathname, $callback->($entries)
717	Unlike the POSIX call of the same name, "aio_readdir" reads an	703	Unlike the POSIX call of the same name, "aio_readdir" reads an
718	entire directory (i.e. opendir + readdir + closedir). The entries	704	entire directory (i.e. opendir + readdir + closedir). The entries
719	will not be sorted, and will NOT include the "." and ".." entries.	705	will not be sorted, and will NOT include the "." and ".." entries.
720		706
…		…
729	The flags are a combination of the following constants, ORed	715	The flags are a combination of the following constants, ORed
730	together (the flags will also be passed to the callback, possibly	716	together (the flags will also be passed to the callback, possibly
731	modified):	717	modified):
732		718
733	IO::AIO::READDIR_DENTS	719	IO::AIO::READDIR_DENTS
734	When this flag is off, then the callback gets an arrayref	720	Normally the callback gets an arrayref consisting of names only
735	consisting of names only (as with "aio_readdir"), otherwise it	721	(as with "aio_readdir"). If this flag is set, then the callback
736	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each	722	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
737	describing a single directory entry in more detail.	723	describing a single directory entry in more detail:
738		724
739	$name is the name of the entry.	725	$name is the name of the entry.
740		726
741	$type is one of the "IO::AIO::DT_xxx" constants:	727	$type is one of the "IO::AIO::DT_xxx" constants:
742		728
743	"IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",	729	"IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
744	"IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",	730	"IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
745	"IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".	731	"IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
746		732
747	"IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If	733	"IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
748	you need to know, you have to run stat yourself. Also, for speed	734	you need to know, you have to run stat yourself. Also, for
749	reasons, the $type scalars are read-only: you can not modify	735	speed/memory reasons, the $type scalars are read-only: you must
750	them.	736	not modify them.
751		737
752	$inode is the inode number (which might not be exact on systems	738	$inode is the inode number (which might not be exact on systems
753	with 64 bit inode numbers and 32 bit perls). This field has	739	with 64 bit inode numbers and 32 bit perls). This field has
754	unspecified content on systems that do not deliver the inode	740	unspecified content on systems that do not deliver the inode
755	information.	741	information.
…		…
767	of which names with short names are tried first.	753	of which names with short names are tried first.
768		754
769	IO::AIO::READDIR_STAT_ORDER	755	IO::AIO::READDIR_STAT_ORDER
770	When this flag is set, then the names will be returned in an	756	When this flag is set, then the names will be returned in an
771	order suitable for stat()'ing each one. That is, when you plan	757	order suitable for stat()'ing each one. That is, when you plan
772	to stat() all files in the given directory, then the returned	758	to stat() most or all files in the given directory, then the
773	order will likely be fastest.	759	returned order will likely be faster.
774		760
775	If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are	761	If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
776	specified, then the likely dirs come first, resulting in a less	762	specified, then the likely dirs come first, resulting in a less
777	optimal stat order.	763	optimal stat order for stat'ing all entries, but likely a more
		764	optimal order for finding subdirectories.
778		765
779	IO::AIO::READDIR_FOUND_UNKNOWN	766	IO::AIO::READDIR_FOUND_UNKNOWN
780	This flag should not be set when calling "aio_readdirx".	767	This flag should not be set when calling "aio_readdirx".
781	Instead, it is being set by "aio_readdirx", when any of the	768	Instead, it is being set by "aio_readdirx", when any of the
782	$type's found were "IO::AIO::DT_UNKNOWN". The absence of this	769	$type's found were "IO::AIO::DT_UNKNOWN". The absence of this
783	flag therefore indicates that all $type's are known, which can	770	flag therefore indicates that all $type's are known, which can
784	be used to speed up some algorithms.	771	be used to speed up some algorithms.
785		772
		773	aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		774	Opens, reads and closes the given file. The data is put into $data,
		775	which is resized as required.
		776
		777	If $offset is negative, then it is counted from the end of the file.
		778
		779	If $length is zero, then the remaining length of the file is used.
		780	Also, in this case, the same limitations to modifying $data apply as
		781	when IO::AIO::mmap is used, i.e. it must only be modified in-place
		782	with "substr". If the size of the file is known, specifying a
		783	non-zero $length results in a performance advantage.
		784
		785	This request is similar to the older "aio_load" request, but since
		786	it is a single request, it might be more efficient to use.
		787
		788	Example: load /etc/passwd into $passwd.
		789
		790	my $passwd;
		791	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		792	$_[0] >= 0
		793	or die "/etc/passwd: $!\n";
		794
		795	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		796	print $passwd;
		797	};
		798	IO::AIO::flush;
		799
786	aio_load $pathname, $data, $callback->($status)	800	aio_load $pathname, $data, $callback->($status)
787	This is a composite request that tries to fully load the given file	801	This is a composite request that tries to fully load the given file
788	into memory. Status is the same as with aio_read.	802	into memory. Status is the same as with aio_read.
		803
		804	Using "aio_slurp" might be more efficient, as it is a single
		805	request.
789		806
790	aio_copy $srcpath, $dstpath, $callback->($status)	807	aio_copy $srcpath, $dstpath, $callback->($status)
791	Try to copy the file (directories not supported as either source	808	Try to copy the file (directories not supported as either source
792	or destination) from $srcpath to $dstpath and call the callback with	809	or destination) from $srcpath to $dstpath and call the callback with
793	a status of 0 (ok) or -1 (error, see $!).	810	a status of 0 (ok) or -1 (error, see $!).
		811
		812	Existing destination files will be truncated.
794		813
795	This is a composite request that creates the destination file with	814	This is a composite request that creates the destination file with
796	mode 0200 and copies the contents of the source file into it using	815	mode 0200 and copies the contents of the source file into it using
797	"aio_sendfile", followed by restoring atime, mtime, access mode and	816	"aio_sendfile", followed by restoring atime, mtime, access mode and
798	uid/gid, in that order.	817	uid/gid, in that order.
…		…
815	to efficiently separate the entries of directory $path into two sets	834	to efficiently separate the entries of directory $path into two sets
816	of names, directories you can recurse into (directories), and ones	835	of names, directories you can recurse into (directories), and ones
817	you cannot recurse into (everything else, including symlinks to	836	you cannot recurse into (everything else, including symlinks to
818	directories).	837	directories).
819		838
820	"aio_scandir" is a composite request that creates of many sub	839	"aio_scandir" is a composite request that generates many sub
821	requests_ $maxreq specifies the maximum number of outstanding aio	840	requests. $maxreq specifies the maximum number of outstanding aio
822	requests that this function generates. If it is "<= 0", then a	841	requests that this function generates. If it is "<= 0", then a
823	suitable default will be chosen (currently 4).	842	suitable default will be chosen (currently 4).
824		843
825	On error, the callback is called without arguments, otherwise it	844	On error, the callback is called without arguments, otherwise it
826	receives two array-refs with path-relative entry names.	845	receives two array-refs with path-relative entry names.
…		…
873	Delete a directory tree starting (and including) $path, return the	892	Delete a directory tree starting (and including) $path, return the
874	status of the final "rmdir" only. This is a composite request that	893	status of the final "rmdir" only. This is a composite request that
875	uses "aio_scandir" to recurse into and rmdir directories, and unlink	894	uses "aio_scandir" to recurse into and rmdir directories, and unlink
876	everything else.	895	everything else.
877		896
		897	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		898	aio_ioctl $fh, $request, $buf, $callback->($status)
		899	These work just like the "fcntl" and "ioctl" built-in functions,
		900	except they execute asynchronously and pass the return value to the
		901	callback.
		902
		903	Both calls can be used for a lot of things, some of which make more
		904	sense to run asynchronously in their own thread, while some others
		905	make less sense. For example, calls that block waiting for external
		906	events, such as locking, will also lock down an I/O thread while it
		907	is waiting, which can deadlock the whole I/O system. At the same
		908	time, there might be no alternative to using a thread to wait.
		909
		910	So in general, you should only use these calls for things that do
		911	(filesystem) I/O, not for things that wait for other events
		912	(network, other processes), although if you are careful and know
		913	what you are doing, you still can.
		914
		915	The following constants are available and can be used for normal
		916	"ioctl" and "fcntl" as well (missing ones are, as usual 0):
		917
		918	"F_DUPFD_CLOEXEC",
		919
		920	"F_OFD_GETLK", "F_OFD_SETLK", "F_OFD_GETLKW",
		921
		922	"FIFREEZE", "FITHAW", "FITRIM", "FICLONE", "FICLONERANGE",
		923	"FIDEDUPERANGE".
		924
		925	"F_ADD_SEALS", "F_GET_SEALS", "F_SEAL_SEAL", "F_SEAL_SHRINK",
		926	"F_SEAL_GROW" and "F_SEAL_WRITE".
		927
		928	"FS_IOC_GETFLAGS", "FS_IOC_SETFLAGS", "FS_IOC_GETVERSION",
		929	"FS_IOC_SETVERSION", "FS_IOC_FIEMAP".
		930
		931	"FS_IOC_FSGETXATTR", "FS_IOC_FSSETXATTR",
		932	"FS_IOC_SET_ENCRYPTION_POLICY", "FS_IOC_GET_ENCRYPTION_PWSALT",
		933	"FS_IOC_GET_ENCRYPTION_POLICY", "FS_KEY_DESCRIPTOR_SIZE".
		934
		935	"FS_SECRM_FL", "FS_UNRM_FL", "FS_COMPR_FL", "FS_SYNC_FL",
		936	"FS_IMMUTABLE_FL", "FS_APPEND_FL", "FS_NODUMP_FL", "FS_NOATIME_FL",
		937	"FS_DIRTY_FL", "FS_COMPRBLK_FL", "FS_NOCOMP_FL", "FS_ENCRYPT_FL",
		938	"FS_BTREE_FL", "FS_INDEX_FL", "FS_JOURNAL_DATA_FL", "FS_NOTAIL_FL",
		939	"FS_DIRSYNC_FL", "FS_TOPDIR_FL", "FS_FL_USER_MODIFIABLE".
		940
		941	"FS_XFLAG_REALTIME", "FS_XFLAG_PREALLOC", "FS_XFLAG_IMMUTABLE",
		942	"FS_XFLAG_APPEND", "FS_XFLAG_SYNC", "FS_XFLAG_NOATIME",
		943	"FS_XFLAG_NODUMP", "FS_XFLAG_RTINHERIT", "FS_XFLAG_PROJINHERIT",
		944	"FS_XFLAG_NOSYMLINKS", "FS_XFLAG_EXTSIZE", "FS_XFLAG_EXTSZINHERIT",
		945	"FS_XFLAG_NODEFRAG", "FS_XFLAG_FILESTREAM", "FS_XFLAG_DAX",
		946	"FS_XFLAG_HASATTR",
		947
878	aio_sync $callback->($status)	948	aio_sync $callback->($status)
879	Asynchronously call sync and call the callback when finished.	949	Asynchronously call sync and call the callback when finished.
880		950
881	aio_fsync $fh, $callback->($status)	951	aio_fsync $fh, $callback->($status)
882	Asynchronously call fsync on the given filehandle and call the	952	Asynchronously call fsync on the given filehandle and call the
…		…
918	Future versions of this function might fall back to other methods	988	Future versions of this function might fall back to other methods
919	when "fsync" on the directory fails (such as calling "sync").	989	when "fsync" on the directory fails (such as calling "sync").
920		990
921	Passes 0 when everything went ok, and -1 on error.	991	Passes 0 when everything went ok, and -1 on error.
922		992
923	aio_msync $scalar, $offset = 0, $length = undef, flags = 0,	993	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
924	$callback->($status)	994	$callback->($status)
925	This is a rather advanced IO::AIO call, which only works on	995	This is a rather advanced IO::AIO call, which only works on
926	mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it	996	mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
927	also works on data scalars managed by the Sys::Mmap or Mmap modules,	997	also works on data scalars managed by the Sys::Mmap or Mmap modules,
928	note that the scalar must only be modified in-place while an aio	998	note that the scalar must only be modified in-place while an aio
…		…
930		1000
931	It calls the "msync" function of your OS, if available, with the	1001	It calls the "msync" function of your OS, if available, with the
932	memory area starting at $offset in the string and ending $length	1002	memory area starting at $offset in the string and ending $length
933	bytes later. If $length is negative, counts from the end, and if	1003	bytes later. If $length is negative, counts from the end, and if
934	$length is "undef", then it goes till the end of the string. The	1004	$length is "undef", then it goes till the end of the string. The
935	flags can be a combination of "IO::AIO::MS_ASYNC",	1005	flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus
936	"IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".	1006	an optional "IO::AIO::MS_INVALIDATE".
937		1007
938	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,	1008	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
939	$callback->($status)	1009	$callback->($status)
940	This is a rather advanced IO::AIO call, which works best on	1010	This is a rather advanced IO::AIO call, which works best on
941	mmap(2)ed scalars.	1011	mmap(2)ed scalars.
942		1012
943	It touches (reads or writes) all memory pages in the specified range	1013	It touches (reads or writes) all memory pages in the specified range
944	inside the scalar. All caveats and parameters are the same as for	1014	inside the scalar. All caveats and parameters are the same as for
945	"aio_msync", above, except for flags, which must be either 0 (which	1015	"aio_msync", above, except for flags, which must be either 0 (which
946	reads all pages and ensures they are instantiated) or	1016	reads all pages and ensures they are instantiated) or
947	"IO::AIO::MT_MODIFY", which modifies the memory page s(by reading	1017	"IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
948	and writing an octet from it, which dirties the page).	1018	and writing an octet from it, which dirties the page).
949		1019
950	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1020	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
951	This is a rather advanced IO::AIO call, which works best on	1021	This is a rather advanced IO::AIO call, which works best on
952	mmap(2)ed scalars.	1022	mmap(2)ed scalars.
…		…
972	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;	1042	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
973	aio_mlock $data; # mlock in background	1043	aio_mlock $data; # mlock in background
974		1044
975	aio_mlockall $flags, $callback->($status)	1045	aio_mlockall $flags, $callback->($status)
976	Calls the "mlockall" function with the given $flags (a combination	1046	Calls the "mlockall" function with the given $flags (a combination
977	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").	1047	of "IO::AIO::MCL_CURRENT", "IO::AIO::MCL_FUTURE" and
		1048	"IO::AIO::MCL_ONFAULT").
978		1049
979	On systems that do not implement "mlockall", this function returns	1050	On systems that do not implement "mlockall", this function returns
980	-1 and sets errno to "ENOSYS".	1051	-1 and sets errno to "ENOSYS". Similarly, flag combinations not
		1052	supported by the system result in a return value of -1 with errno
		1053	being set to "EINVAL".
981		1054
982	Note that the corresponding "munlockall" is synchronous and is	1055	Note that the corresponding "munlockall" is synchronous and is
983	documented under "MISCELLANEOUS FUNCTIONS".	1056	documented under "MISCELLANEOUS FUNCTIONS".
984		1057
985	Example: asynchronously lock all current and future pages into	1058	Example: asynchronously lock all current and future pages into
…		…
1027	"IO::AIO::FIEMAP_EXTENT_DATA_INLINE",	1100	"IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1028	"IO::AIO::FIEMAP_EXTENT_DATA_TAIL",	1101	"IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1029	"IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"	1102	"IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1030	or "IO::AIO::FIEMAP_EXTENT_SHARED".	1103	or "IO::AIO::FIEMAP_EXTENT_SHARED".
1031		1104
1032	At the time of this writing (Linux 3.2), this requets is unreliable	1105	At the time of this writing (Linux 3.2), this request is unreliable
1033	unless $count is "undef", as the kernel has all sorts of bugs	1106	unless $count is "undef", as the kernel has all sorts of bugs
1034	preventing it to return all extents of a range for files with large	1107	preventing it to return all extents of a range for files with a
1035	number of extents. The code works around all these issues if $count	1108	large number of extents. The code (only) works around all these
1036	is undef.	1109	issues if $count is "undef".
1037		1110
1038	aio_group $callback->(...)	1111	aio_group $callback->(...)
1039	This is a very special aio request: Instead of doing something, it	1112	This is a very special aio request: Instead of doing something, it
1040	is a container for other aio requests, which is useful if you want	1113	is a container for other aio requests, which is useful if you want
1041	to bundle many requests into a single, composite, request with a	1114	to bundle many requests into a single, composite, request with a
…		…
1121	aio_stat [$etcdir, "passwd"], sub {	1194	aio_stat [$etcdir, "passwd"], sub {
1122	# yay	1195	# yay
1123	};	1196	};
1124	};	1197	};
1125		1198
1126	That "aio_wd" is a request and not a normal function shows that creating	1199	The fact that "aio_wd" is a request and not a normal function shows that
1127	an IO::AIO::WD object is itself a potentially blocking operation, which	1200	creating an IO::AIO::WD object is itself a potentially blocking
1128	is why it is done asynchronously.	1201	operation, which is why it is done asynchronously.
1129		1202
1130	To stat the directory obtained with "aio_wd" above, one could write	1203	To stat the directory obtained with "aio_wd" above, one could write
1131	either of the following three request calls:	1204	either of the following three request calls:
1132		1205
1133	aio_lstat "/etc" , sub { ... # pathname as normal string	1206	aio_lstat "/etc" , sub { ... # pathname as normal string
…		…
1150	There are some caveats: when directories get renamed (or deleted), the	1223	There are some caveats: when directories get renamed (or deleted), the
1151	pathname string doesn't change, so will point to the new directory (or	1224	pathname string doesn't change, so will point to the new directory (or
1152	nowhere at all), while the directory fd, if available on the system,	1225	nowhere at all), while the directory fd, if available on the system,
1153	will still point to the original directory. Most functions accepting a	1226	will still point to the original directory. Most functions accepting a
1154	pathname will use the directory fd on newer systems, and the string on	1227	pathname will use the directory fd on newer systems, and the string on
1155	older systems. Some functions (such as realpath) will always rely on the	1228	older systems. Some functions (such as "aio_realpath") will always rely
1156	string form of the pathname.	1229	on the string form of the pathname.
1157		1230
1158	So this fucntionality is mainly useful to get some protection against	1231	So this functionality is mainly useful to get some protection against
1159	"chdir", to easily get an absolute path out of a relative path for	1232	"chdir", to easily get an absolute path out of a relative path for
1160	future reference, and to speed up doing many operations in the same	1233	future reference, and to speed up doing many operations in the same
1161	directory (e.g. when stat'ing all files in a directory).	1234	directory (e.g. when stat'ing all files in a directory).
1162		1235
1163	The following functions implement this working directory abstraction:	1236	The following functions implement this working directory abstraction:
…		…
1173	Since passing "undef" as working directory component of a pathname	1246	Since passing "undef" as working directory component of a pathname
1174	fails the request with "ENOENT", there is often no need for error	1247	fails the request with "ENOENT", there is often no need for error
1175	checking in the "aio_wd" callback, as future requests using the	1248	checking in the "aio_wd" callback, as future requests using the
1176	value will fail in the expected way.	1249	value will fail in the expected way.
1177		1250
1178	If this call isn't available because your OS lacks it or it couldn't
1179	be detected, it will be emulated by calling "fsync" instead.
1180
1181	IO::AIO::CWD	1251	IO::AIO::CWD
1182	This is a compiletime constant (object) that represents the process	1252	This is a compile time constant (object) that represents the process
1183	current working directory.	1253	current working directory.
1184		1254
1185	Specifying this object as working directory object for a pathname is	1255	Specifying this object as working directory object for a pathname is
1186	as if the pathname would be specified directly, without a directory	1256	as if the pathname would be specified directly, without a directory
1187	object, e.g., these calls are functionally identical:	1257	object. For example, these calls are functionally identical:
1188		1258
1189	aio_stat "somefile", sub { ... };	1259	aio_stat "somefile", sub { ... };
1190	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };	1260	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1261
		1262	To recover the path associated with an IO::AIO::WD object, you can use
		1263	"aio_realpath":
		1264
		1265	aio_realpath $wd, sub {
		1266	warn "path is $_[0]\n";
		1267	};
		1268
		1269	Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir"
		1270	sometimes, fall back to using an absolue path.
1191		1271
1192	IO::AIO::REQ CLASS	1272	IO::AIO::REQ CLASS
1193	All non-aggregate "aio_*" functions return an object of this class when	1273	All non-aggregate "aio_*" functions return an object of this class when
1194	called in non-void context.	1274	called in non-void context.
1195		1275
…		…
1347	results.	1427	results.
1348		1428
1349	See "poll_cb" for an example.	1429	See "poll_cb" for an example.
1350		1430
1351	IO::AIO::poll_cb	1431	IO::AIO::poll_cb
1352	Process some outstanding events on the result pipe. You have to call	1432	Process some requests that have reached the result phase (i.e. they
		1433	have been executed but the results are not yet reported). You have
		1434	to call this "regularly" to finish outstanding requests.
		1435
1353	this regularly. Returns 0 if all events could be processed (or there	1436	Returns 0 if all events could be processed (or there were no events
1354	were no events to process), or -1 if it returned earlier for	1437	to process), or -1 if it returned earlier for whatever reason.
1355	whatever reason. Returns immediately when no events are outstanding.	1438	Returns immediately when no events are outstanding. The amount of
1356	The amount of events processed depends on the settings of	1439	events processed depends on the settings of "IO::AIO::max_poll_req",
1357	"IO::AIO::max_poll_req" and "IO::AIO::max_poll_time".	1440	"IO::AIO::max_poll_time" and "IO::AIO::max_outstanding".
1358		1441
1359	If not all requests were processed for whatever reason, the	1442	If not all requests were processed for whatever reason, the poll
1360	filehandle will still be ready when "poll_cb" returns, so normally	1443	file descriptor will still be ready when "poll_cb" returns, so
1361	you don't have to do anything special to have it called later.	1444	normally you don't have to do anything special to have it called
		1445	later.
1362		1446
1363	Apart from calling "IO::AIO::poll_cb" when the event filehandle	1447	Apart from calling "IO::AIO::poll_cb" when the event filehandle
1364	becomes ready, it can be beneficial to call this function from loops	1448	becomes ready, it can be beneficial to call this function from loops
1365	which submit a lot of requests, to make sure the results get	1449	which submit a lot of requests, to make sure the results get
1366	processed when they become available and not just when the loop is	1450	processed when they become available and not just when the loop is
…		…
1374	Event->io (fd => IO::AIO::poll_fileno,	1458	Event->io (fd => IO::AIO::poll_fileno,
1375	poll => 'r', async => 1,	1459	poll => 'r', async => 1,
1376	cb => \&IO::AIO::poll_cb);	1460	cb => \&IO::AIO::poll_cb);
1377		1461
1378	IO::AIO::poll_wait	1462	IO::AIO::poll_wait
1379	If there are any outstanding requests and none of them in the result	1463	Wait until either at least one request is in the result phase or no
1380	phase, wait till the result filehandle becomes ready for reading	1464	requests are outstanding anymore.
1381	(simply does a "select" on the filehandle. This is useful if you	1465
1382	want to synchronously wait for some requests to finish).	1466	This is useful if you want to synchronously wait for some requests
		1467	to become ready, without actually handling them.
1383		1468
1384	See "nreqs" for an example.	1469	See "nreqs" for an example.
1385		1470
1386	IO::AIO::poll	1471	IO::AIO::poll
1387	Waits until some requests have been handled.	1472	Waits until some requests have been handled.
…		…
1396		1481
1397	Strictly equivalent to:	1482	Strictly equivalent to:
1398		1483
1399	IO::AIO::poll_wait, IO::AIO::poll_cb	1484	IO::AIO::poll_wait, IO::AIO::poll_cb
1400	while IO::AIO::nreqs;	1485	while IO::AIO::nreqs;
		1486
		1487	This function can be useful at program aborts, to make sure
		1488	outstanding I/O has been done ("IO::AIO" uses an "END" block which
		1489	already calls this function on normal exits), or when you are merely
		1490	using "IO::AIO" for its more advanced functions, rather than for
		1491	async I/O, e.g.:
		1492
		1493	my ($dirs, $nondirs);
		1494	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1495	IO::AIO::flush;
		1496	# $dirs, $nondirs are now set
1401		1497
1402	IO::AIO::max_poll_reqs $nreqs	1498	IO::AIO::max_poll_reqs $nreqs
1403	IO::AIO::max_poll_time $seconds	1499	IO::AIO::max_poll_time $seconds
1404	These set the maximum number of requests (default 0, meaning	1500	These set the maximum number of requests (default 0, meaning
1405	infinity) that are being processed by "IO::AIO::poll_cb" in one	1501	infinity) that are being processed by "IO::AIO::poll_cb" in one
…		…
1499		1595
1500	This is a very bad function to use in interactive programs because	1596	This is a very bad function to use in interactive programs because
1501	it blocks, and a bad way to reduce concurrency because it is	1597	it blocks, and a bad way to reduce concurrency because it is
1502	inexact: Better use an "aio_group" together with a feed callback.	1598	inexact: Better use an "aio_group" together with a feed callback.
1503		1599
1504	It's main use is in scripts without an event loop - when you want to	1600	Its main use is in scripts without an event loop - when you want to
1505	stat a lot of files, you can write somehting like this:	1601	stat a lot of files, you can write something like this:
1506		1602
1507	IO::AIO::max_outstanding 32;	1603	IO::AIO::max_outstanding 32;
1508		1604
1509	for my $path (...) {	1605	for my $path (...) {
1510	aio_stat $path , ...;	1606	aio_stat $path , ...;
…		…
1539		1635
1540	IO::AIO::npending	1636	IO::AIO::npending
1541	Returns the number of requests currently in the pending state	1637	Returns the number of requests currently in the pending state
1542	(executed, but not yet processed by poll_cb).	1638	(executed, but not yet processed by poll_cb).
1543		1639
		1640	SUBSECOND STAT TIME ACCESS
		1641	Both "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" functions can
		1642	generally find access/modification and change times with subsecond time
		1643	accuracy of the system supports it, but perl's built-in functions only
		1644	return the integer part.
		1645
		1646	The following functions return the timestamps of the most recent stat
		1647	with subsecond precision on most systems and work both after
		1648	"aio_stat"/"aio_lstat" and perl's "stat"/"lstat" calls. Their return
		1649	value is only meaningful after a successful "stat"/"lstat" call, or
		1650	during/after a successful "aio_stat"/"aio_lstat" callback.
		1651
		1652	This is similar to the Time::HiRes "stat" functions, but can return full
		1653	resolution without rounding and work with standard perl "stat",
		1654	alleviating the need to call the special "Time::HiRes" functions, which
		1655	do not act like their perl counterparts.
		1656
		1657	On operating systems or file systems where subsecond time resolution is
		1658	not supported or could not be detected, a fractional part of 0 is
		1659	returned, so it is always safe to call these functions.
		1660
		1661	$seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime,
		1662	IO::AIO::st_btime
		1663	Return the access, modication, change or birth time, respectively,
		1664	including fractional part. Due to the limited precision of floating
		1665	point, the accuracy on most platforms is only a bit better than
		1666	milliseconds for times around now - see the nsec function family,
		1667	below, for full accuracy.
		1668
		1669	File birth time is only available when the OS and perl support it
		1670	(on FreeBSD and NetBSD at the time of this writing, although support
		1671	is adaptive, so if your OS/perl gains support, IO::AIO can take
		1672	advantage of it). On systems where it isn't available, 0 is
		1673	currently returned, but this might change to "undef" in a future
		1674	version.
		1675
		1676	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		1677	Returns access, modification, change and birth time all in one go,
		1678	and maybe more times in the future version.
		1679
		1680	$nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec,
		1681	IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		1682	Return the fractional access, modifcation, change or birth time, in
		1683	nanoseconds, as an integer in the range 0 to 999999999.
		1684
		1685	Note that no accessors are provided for access, modification and
		1686	change times - you need to get those from "stat _" if required ("int
		1687	IO::AIO::st_atime" and so on will not generally give you the
		1688	correct value).
		1689
		1690	$seconds = IO::AIO::st_btimesec
		1691	The (integral) seconds part of the file birth time, if available.
		1692
		1693	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		1694	Like the functions above, but returns all four times in one go (and
		1695	maybe more in future versions).
		1696
		1697	$counter = IO::AIO::st_gen
		1698	Returns the generation counter (in practice this is just a random
		1699	number) of the file. This is only available on platforms which have
		1700	this member in their "struct stat" (most BSDs at the time of this
		1701	writing) and generally only to the root usert. If unsupported, 0 is
		1702	returned, but this might change to "undef" in a future version.
		1703
		1704	Example: print the high resolution modification time of /etc, using
		1705	"stat", and "IO::AIO::aio_stat".
		1706
		1707	if (stat "/etc") {
		1708	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		1709	}
		1710
		1711	IO::AIO::aio_stat "/etc", sub {
		1712	$_[0]
		1713	and return;
		1714
		1715	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		1716	};
		1717
		1718	IO::AIO::flush;
		1719
		1720	Output of the awbove on my system, showing reduced and full accuracy:
		1721
		1722	stat(/etc) mtime: 1534043702.020808
		1723	aio_stat(/etc) mtime: 1534043702.020807792
		1724
1544	MISCELLANEOUS FUNCTIONS	1725	MISCELLANEOUS FUNCTIONS
1545	IO::AIO implements some functions that might be useful, but are not	1726	IO::AIO implements some functions that are useful when you want to use
1546	asynchronous.	1727	some "Advanced I/O" function not available to in Perl, without going the
		1728	"Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
		1729	counterpart.
		1730
		1731	$numfd = IO::AIO::get_fdlimit
		1732	Tries to find the current file descriptor limit and returns it, or
		1733	"undef" and sets $! in case of an error. The limit is one larger
		1734	than the highest valid file descriptor number.
		1735
		1736	IO::AIO::min_fdlimit [$numfd]
		1737	Try to increase the current file descriptor limit(s) to at least
		1738	$numfd by changing the soft or hard file descriptor resource limit.
		1739	If $numfd is missing, it will try to set a very high limit, although
		1740	this is not recommended when you know the actual minimum that you
		1741	require.
		1742
		1743	If the limit cannot be raised enough, the function makes a
		1744	best-effort attempt to increase the limit as much as possible, using
		1745	various tricks, while still failing. You can query the resulting
		1746	limit using "IO::AIO::get_fdlimit".
		1747
		1748	If an error occurs, returns "undef" and sets $!, otherwise returns
		1749	true.
1547		1750
1548	IO::AIO::sendfile $ofh, $ifh, $offset, $count	1751	IO::AIO::sendfile $ofh, $ifh, $offset, $count
1549	Calls the "eio_sendfile_sync" function, which is like	1752	Calls the "eio_sendfile_sync" function, which is like
1550	"aio_sendfile", but is blocking (this makes most sense if you know	1753	"aio_sendfile", but is blocking (this makes most sense if you know
1551	the input data is likely cached already and the output filehandle is	1754	the input data is likely cached already and the output filehandle is
…		…
1568	details). The following advice constants are available:	1771	details). The following advice constants are available:
1569	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",	1772	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1570	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",	1773	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1571	"IO::AIO::MADV_DONTNEED".	1774	"IO::AIO::MADV_DONTNEED".
1572		1775
		1776	If $offset is negative, counts from the end. If $length is negative,
		1777	the remaining length of the $scalar is used. If possible, $length
		1778	will be reduced to fit into the $scalar.
		1779
1573	On systems that do not implement "posix_madvise", this function	1780	On systems that do not implement "posix_madvise", this function
1574	returns ENOSYS, otherwise the return value of "posix_madvise".	1781	returns ENOSYS, otherwise the return value of "posix_madvise".
1575		1782
1576	IO::AIO::mprotect $scalar, $offset, $len, $protect	1783	IO::AIO::mprotect $scalar, $offset, $len, $protect
1577	Simply calls the "mprotect" function on the preferably AIO::mmap'ed	1784	Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1578	$scalar (see its manpage for details). The following protect	1785	$scalar (see its manpage for details). The following protect
1579	constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",	1786	constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1580	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".	1787	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1581		1788
		1789	If $offset is negative, counts from the end. If $length is negative,
		1790	the remaining length of the $scalar is used. If possible, $length
		1791	will be reduced to fit into the $scalar.
		1792
1582	On systems that do not implement "mprotect", this function returns	1793	On systems that do not implement "mprotect", this function returns
1583	ENOSYS, otherwise the return value of "mprotect".	1794	ENOSYS, otherwise the return value of "mprotect".
1584		1795
1585	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	1796	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1586	Memory-maps a file (or anonymous memory range) and attaches it to	1797	Memory-maps a file (or anonymous memory range) and attaches it to
1587	the given $scalar, which will act like a string scalar. Returns true	1798	the given $scalar, which will act like a string scalar. Returns true
1588	on success, and false otherwise.	1799	on success, and false otherwise.
1589		1800
		1801	The scalar must exist, but its contents do not matter - this means
		1802	you cannot use a nonexistant array or hash element. When in doubt,
		1803	"undef" the scalar first.
		1804
1590	The only operations allowed on the scalar are "substr"/"vec" that	1805	The only operations allowed on the mmapped scalar are
1591	don't change the string length, and most read-only operations such	1806	"substr"/"vec", which don't change the string length, and most
1592	as copying it or searching it with regexes and so on.	1807	read-only operations such as copying it or searching it with regexes
		1808	and so on.
1593		1809
1594	Anything else is unsafe and will, at best, result in memory leaks.	1810	Anything else is unsafe and will, at best, result in memory leaks.
1595		1811
1596	The memory map associated with the $scalar is automatically removed	1812	The memory map associated with the $scalar is automatically removed
1597	when the $scalar is destroyed, or when the "IO::AIO::mmap" or	1813	when the $scalar is undef'd or destroyed, or when the
1598	"IO::AIO::munmap" functions are called.	1814	"IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1599		1815
1600	This calls the "mmap"(2) function internally. See your system's	1816	This calls the "mmap"(2) function internally. See your system's
1601	manual page for details on the $length, $prot and $flags parameters.	1817	manual page for details on the $length, $prot and $flags parameters.
1602		1818
1603	The $length must be larger than zero and smaller than the actual	1819	The $length must be larger than zero and smaller than the actual
…		…
1607	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or	1823	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1608	"IO::AIO::PROT_WRITE",	1824	"IO::AIO::PROT_WRITE",
1609		1825
1610	$flags can be a combination of "IO::AIO::MAP_SHARED" or	1826	$flags can be a combination of "IO::AIO::MAP_SHARED" or
1611	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when	1827	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1612	not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"	1828	not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1613	(which is set to "MAP_ANON" if your system only provides this	1829	"MAP_ANON" if your system only provides this constant),
		1830	"IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1614	constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",	1831	"IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
		1832	"IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1615	"IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or	1833	"IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB" or
1616	"IO::AIO::MAP_NONBLOCK"	1834	"IO::AIO::MAP_STACK".
1617		1835
1618	If $fh is "undef", then a file descriptor of -1 is passed.	1836	If $fh is "undef", then a file descriptor of -1 is passed.
1619		1837
1620	$offset is the offset from the start of the file - it generally must	1838	$offset is the offset from the start of the file - it generally must
1621	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.	1839	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
…		…
1633		1851
1634	my $fast_md5 = md5 $data;	1852	my $fast_md5 = md5 $data;
1635		1853
1636	IO::AIO::munmap $scalar	1854	IO::AIO::munmap $scalar
1637	Removes a previous mmap and undefines the $scalar.	1855	Removes a previous mmap and undefines the $scalar.
		1856
		1857	IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[,
		1858	$new_address = 0]
		1859	Calls the Linux-specific mremap(2) system call. The $scalar must
		1860	have been mapped by "IO::AIO::mmap", and $flags must currently
		1861	either be 0 or "IO::AIO::MREMAP_MAYMOVE".
		1862
		1863	Returns true if successful, and false otherwise. If the underlying
		1864	mmapped region has changed address, then the true value has the
		1865	numerical value 1, otherwise it has the numerical value 0:
		1866
		1867	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		1868	or die "mremap: $!";
		1869
		1870	if ($success*1) {
		1871	warn "scalar has chanegd address in memory\n";
		1872	}
		1873
		1874	"IO::AIO::MREMAP_FIXED" and the $new_address argument are currently
		1875	implemented, but not supported and might go away in a future
		1876	version.
		1877
		1878	On systems where this call is not supported or is not emulated, this
		1879	call returns falls and sets $! to "ENOSYS".
		1880
		1881	IO::AIO::mlockall $flags
		1882	Calls the "eio_mlockall_sync" function, which is like
		1883	"aio_mlockall", but is blocking.
1638		1884
1639	IO::AIO::munlock $scalar, $offset = 0, $length = undef	1885	IO::AIO::munlock $scalar, $offset = 0, $length = undef
1640	Calls the "munlock" function, undoing the effects of a previous	1886	Calls the "munlock" function, undoing the effects of a previous
1641	"aio_mlock" call (see its description for details).	1887	"aio_mlock" call (see its description for details).
1642		1888
1643	IO::AIO::munlockall	1889	IO::AIO::munlockall
1644	Calls the "munlockall" function.	1890	Calls the "munlockall" function.
1645		1891
1646	On systems that do not implement "munlockall", this function returns	1892	On systems that do not implement "munlockall", this function returns
1647	ENOSYS, otherwise the return value of "munlockall".	1893	ENOSYS, otherwise the return value of "munlockall".
		1894
		1895	$fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		1896	Uses the GNU/Linux accept4(2) syscall, if available, to accept a
		1897	socket and return the new file handle on success, or sets $! and
		1898	returns "undef" on error.
		1899
		1900	The remote name of the new socket will be stored in $sockaddr, which
		1901	will be extended to allow for at least $sockaddr_maxlen octets. If
		1902	the socket name does not fit into $sockaddr_maxlen octets, this is
		1903	signaled by returning a longer string in $sockaddr, which might or
		1904	might not be truncated.
		1905
		1906	To accept name-less sockets, use "undef" for $sockaddr and 0 for
		1907	$sockaddr_maxlen.
		1908
		1909	The main reasons to use this syscall rather than portable accept(2)
		1910	are that you can specify "SOCK_NONBLOCK" and/or "SOCK_CLOEXEC" flags
		1911	and you can accept name-less sockets by specifying 0 for
		1912	$sockaddr_maxlen, which is sadly not possible with perl's interface
		1913	to "accept".
1648		1914
1649	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags	1915	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1650	Calls the GNU/Linux splice(2) syscall, if available. If $r_off or	1916	Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1651	$w_off are "undef", then "NULL" is passed for these, otherwise they	1917	$w_off are "undef", then "NULL" is passed for these, otherwise they
1652	should be the file offset.	1918	should be the file offset.
…		…
1659	"IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".	1925	"IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1660		1926
1661	See the splice(2) manpage for details.	1927	See the splice(2) manpage for details.
1662		1928
1663	IO::AIO::tee $r_fh, $w_fh, $length, $flags	1929	IO::AIO::tee $r_fh, $w_fh, $length, $flags
1664	Calls the GNU/Linux tee(2) syscall, see it's manpage and the	1930	Calls the GNU/Linux tee(2) syscall, see its manpage and the
1665	description for "IO::AIO::splice" above for details.	1931	description for "IO::AIO::splice" above for details.
		1932
		1933	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		1934	Attempts to query or change the pipe buffer size. Obviously works
		1935	only on pipes, and currently works only on GNU/Linux systems, and
		1936	fails with -1/"ENOSYS" everywhere else. If anybody knows how to
		1937	influence pipe buffer size on other systems, drop me a note.
		1938
		1939	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		1940	This is a direct interface to the Linux pipe2(2) system call. If
		1941	$flags is missing or 0, then this should be the same as a call to
		1942	perl's built-in "pipe" function and create a new pipe, and works on
		1943	systems that lack the pipe2 syscall. On win32, this case invokes
		1944	"_pipe (..., 4096, O_BINARY)".
		1945
		1946	If $flags is non-zero, it tries to invoke the pipe2 system call with
		1947	the given flags (Linux 2.6.27, glibc 2.9).
		1948
		1949	On success, the read and write file handles are returned.
		1950
		1951	On error, nothing will be returned. If the pipe2 syscall is missing
		1952	and $flags is non-zero, fails with "ENOSYS".
		1953
		1954	Please refer to pipe2(2) for more info on the $flags, but at the
		1955	time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
		1956	and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
		1957	supported.
		1958
		1959	Example: create a pipe race-free w.r.t. threads and fork:
		1960
		1961	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		1962	or die "pipe2: $!\n";
		1963
		1964	$fh = IO::AIO::memfd_create $pathname[, $flags]
		1965	This is a direct interface to the Linux memfd_create(2) system call.
		1966	The (unhelpful) default for $flags is 0, but your default should be
		1967	"IO::AIO::MFD_CLOEXEC".
		1968
		1969	On success, the new memfd filehandle is returned, otherwise returns
		1970	"undef". If the memfd_create syscall is missing, fails with
		1971	"ENOSYS".
		1972
		1973	Please refer to memfd_create(2) for more info on this call.
		1974
		1975	The following $flags values are available: "IO::AIO::MFD_CLOEXEC",
		1976	"IO::AIO::MFD_ALLOW_SEALING" and "IO::AIO::MFD_HUGETLB".
		1977
		1978	Example: create a new memfd.
		1979
		1980	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		1981	or die "memfd_create: $!\n";
		1982
		1983	$fh = IO::AIO::pidfd_open $pid[, $flags]
		1984	This is an interface to the Linux pidfd_open(2) system call. The
		1985	default for $flags is 0.
		1986
		1987	On success, a new pidfd filehandle is returned (that is already set
		1988	to close-on-exec), otherwise returns "undef". If the syscall is
		1989	missing, fails with "ENOSYS".
		1990
		1991	Example: open pid 6341 as pidfd.
		1992
		1993	my $fh = IO::AIO::pidfd_open 6341
		1994	or die "pidfd_open: $!\n";
		1995
		1996	$status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[,
		1997	$flags]]
		1998	This is an interface to the Linux pidfd_send_signal system call. The
		1999	default for $siginfo is "undef" and the default for $flags is 0.
		2000
		2001	Returns the system call status. If the syscall is missing, fails
		2002	with "ENOSYS".
		2003
		2004	When specified, $siginfo must be a reference to a hash with one or
		2005	more of the following members:
		2006
		2007	code - the "si_code" member
		2008	pid - the "si_pid" member
		2009	uid - the "si_uid" member
		2010	value_int - the "si_value.sival_int" member
		2011	value_ptr - the "si_value.sival_ptr" member, specified as an integer
		2012
		2013	Example: send a SIGKILL to the specified process.
		2014
		2015	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
		2016	and die "pidfd_send_signal: $!\n";
		2017
		2018	Example: send a SIGKILL to the specified process with extra data.
		2019
		2020	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
		2021	and die "pidfd_send_signal: $!\n";
		2022
		2023	$fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		2024	This is an interface to the Linux pidfd_getfd system call. The
		2025	default for $flags is 0.
		2026
		2027	On success, returns a dup'ed copy of the target file descriptor
		2028	(specified as an integer) returned (that is already set to
		2029	close-on-exec), otherwise returns "undef". If the syscall is
		2030	missing, fails with "ENOSYS".
		2031
		2032	Example: get a copy of standard error of another process and print
		2033	soemthing to it.
		2034
		2035	my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
		2036	or die "pidfd_getfd: $!\n";
		2037	print $errfh "stderr\n";
		2038
		2039	$fh = IO::AIO::eventfd [$initval, [$flags]]
		2040	This is a direct interface to the Linux eventfd(2) system call. The
		2041	(unhelpful) defaults for $initval and $flags are 0 for both.
		2042
		2043	On success, the new eventfd filehandle is returned, otherwise
		2044	returns "undef". If the eventfd syscall is missing, fails with
		2045	"ENOSYS".
		2046
		2047	Please refer to eventfd(2) for more info on this call.
		2048
		2049	The following symbol flag values are available:
		2050	"IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
		2051	"IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
		2052
		2053	Example: create a new eventfd filehandle:
		2054
		2055	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2056	or die "eventfd: $!\n";
		2057
		2058	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		2059	This is a direct interface to the Linux timerfd_create(2) system
		2060	call. The (unhelpful) default for $flags is 0, but your default
		2061	should be "IO::AIO::TFD_CLOEXEC".
		2062
		2063	On success, the new timerfd filehandle is returned, otherwise
		2064	returns "undef". If the timerfd_create syscall is missing, fails
		2065	with "ENOSYS".
		2066
		2067	Please refer to timerfd_create(2) for more info on this call.
		2068
		2069	The following $clockid values are available:
		2070	"IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
		2071	"IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
		2072	"IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
		2073	"IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
		2074
		2075	The following $flags values are available (Linux 2.6.27):
		2076	"IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
		2077
		2078	Example: create a new timerfd and set it to one-second repeated
		2079	alarms, then wait for two alarms:
		2080
		2081	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2082	or die "timerfd_create: $!\n";
		2083
		2084	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2085	or die "timerfd_settime: $!\n";
		2086
		2087	for (1..2) {
		2088	8 == sysread $fh, my $buf, 8
		2089	or die "timerfd read failure\n";
		2090
		2091	printf "number of expirations (likely 1): %d\n",
		2092	unpack "Q", $buf;
		2093	}
		2094
		2095	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
		2096	$new_interval, $nbw_value
		2097	This is a direct interface to the Linux timerfd_settime(2) system
		2098	call. Please refer to its manpage for more info on this call.
		2099
		2100	The new itimerspec is specified using two (possibly fractional)
		2101	second values, $new_interval and $new_value).
		2102
		2103	On success, the current interval and value are returned (as per
		2104	"timerfd_gettime"). On failure, the empty list is returned.
		2105
		2106	The following $flags values are available:
		2107	"IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
		2108
		2109	See "IO::AIO::timerfd_create" for a full example.
		2110
		2111	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2112	This is a direct interface to the Linux timerfd_gettime(2) system
		2113	call. Please refer to its manpage for more info on this call.
		2114
		2115	On success, returns the current values of interval and value for the
		2116	given timerfd (as potentially fractional second values). On failure,
		2117	the empty list is returned.
1666		2118
1667	EVENT LOOP INTEGRATION	2119	EVENT LOOP INTEGRATION
1668	It is recommended to use AnyEvent::AIO to integrate IO::AIO	2120	It is recommended to use AnyEvent::AIO to integrate IO::AIO
1669	automatically into many event loops:	2121	automatically into many event loops:
1670		2122
…		…
1720	forking, if "IO::AIO" was used in the parent. Calling it while	2172	forking, if "IO::AIO" was used in the parent. Calling it while
1721	IO::AIO is active in the process will result in undefined behaviour.	2173	IO::AIO is active in the process will result in undefined behaviour.
1722	Calling it at any time will also result in any undefined (by POSIX)	2174	Calling it at any time will also result in any undefined (by POSIX)
1723	behaviour.	2175	behaviour.
1724		2176
		2177	LINUX-SPECIFIC CALLS
		2178	When a call is documented as "linux-specific" then this means it
		2179	originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
		2180	availability and compatibility of such calls regardless of the platform
		2181	it is compiled on, so platforms such as FreeBSD which often implement
		2182	these calls will work. When in doubt, call them and see if they fail wth
		2183	"ENOSYS".
		2184
1725	MEMORY USAGE	2185	MEMORY USAGE
1726	Per-request usage:	2186	Per-request usage:
1727		2187
1728	Each aio request uses - depending on your architecture - around 100-200	2188	Each aio request uses - depending on your architecture - around 100-200
1729	bytes of memory. In addition, stat requests need a stat buffer (possibly	2189	bytes of memory. In addition, stat requests need a stat buffer (possibly
…		…
1739	In the execution phase, some aio requests require more memory for	2199	In the execution phase, some aio requests require more memory for
1740	temporary buffers, and each thread requires a stack and other data	2200	temporary buffers, and each thread requires a stack and other data
1741	structures (usually around 16k-128k, depending on the OS).	2201	structures (usually around 16k-128k, depending on the OS).
1742		2202
1743	KNOWN BUGS	2203	KNOWN BUGS
1744	Known bugs will be fixed in the next release.	2204	Known bugs will be fixed in the next release :)
		2205
		2206	KNOWN ISSUES
		2207	Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
		2208	or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
		2209	non-created hash slots or other scalars I didn't think of. It's best to
		2210	avoid such and either use scalar variables or making sure that the
		2211	scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
		2212
		2213	I am not sure anything can be done about this, so this is considered a
		2214	known issue, rather than a bug.
1745		2215
1746	SEE ALSO	2216	SEE ALSO
1747	AnyEvent::AIO for easy integration into event loops, Coro::AIO for a	2217	AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1748	more natural syntax.	2218	more natural syntax and IO::FDPass for file descriptor passing.
1749		2219
1750	AUTHOR	2220	AUTHOR
1751	Marc Lehmann <schmorp@schmorp.de>	2221	Marc Lehmann <schmorp@schmorp.de>
1752	http://home.schmorp.de/	2222	http://home.schmorp.de/
1753		2223

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Revision 1.53 by root, Thu Oct 11 03:20:52 2012 UTC vs.
Revision 1.66 by root, Tue Dec 29 15:20:12 2020 UTC