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

Comparing IO-AIO/README (file contents):
Revision 1.54 by root, Sun Jan 6 11:48:14 2013 UTC vs.
Revision 1.70 by root, Sat Apr 1 02:14:05 2023 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	IO::AIO::fexecve $fh, $argv, $envp
		234
223	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]	235	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
224	IO::AIO::munmap $scalar	236	IO::AIO::munmap $scalar
		237	IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
225	IO::AIO::madvise $scalar, $offset, $length, $advice	238	IO::AIO::madvise $scalar, $offset, $length, $advice
226	IO::AIO::mprotect $scalar, $offset, $length, $protect	239	IO::AIO::mprotect $scalar, $offset, $length, $protect
227	IO::AIO::munlock $scalar, $offset = 0, $length = undef	240	IO::AIO::munlock $scalar, $offset = 0, $length = undef
228	IO::AIO::munlockall	241	IO::AIO::munlockall
		242
		243	# stat extensions
		244	$counter = IO::AIO::st_gen
		245	$seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		246	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		247	$nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		248	$seconds = IO::AIO::st_btimesec
		249	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		250
		251	# very much unportable syscalls
		252	IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
		253	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		254	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		255
		256	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		257	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		258
		259	$fh = IO::AIO::eventfd [$initval, [$flags]]
		260	$fh = IO::AIO::memfd_create $pathname[, $flags]
		261
		262	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		263	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		264	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		265
		266	$fh = IO::AIO::pidfd_open $pid[, $flags]
		267	$status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		268	$fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		269
		270	$retval = IO::AIO::mount $special, $path, $fstype, $flags = 0, $data = undef
		271	$retval = IO::AIO::umount $path, $flags = 0
229		272
230	API NOTES	273	API NOTES
231	All the "aio_*" calls are more or less thin wrappers around the syscall	274	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	275	with the same name (sans "aio_"). The arguments are similar or
233	identical, and they all accept an additional (and optional) $callback	276	identical, and they all accept an additional (and optional) $callback
…		…
300	aio_open $pathname, $flags, $mode, $callback->($fh)	343	aio_open $pathname, $flags, $mode, $callback->($fh)
301	Asynchronously open or create a file and call the callback with a	344	Asynchronously open or create a file and call the callback with a
302	newly created filehandle for the file (or "undef" in case of an	345	newly created filehandle for the file (or "undef" in case of an
303	error).	346	error).
304		347
305	The pathname passed to "aio_open" must be absolute. See API NOTES,
306	above, for an explanation.
307
308	The $flags argument is a bitmask. See the "Fcntl" module for a list.	348	The $flags argument is a bitmask. See the "Fcntl" module for a list.
309	They are the same as used by "sysopen".	349	They are the same as used by "sysopen".
310		350
311	Likewise, $mode specifies the mode of the newly created file, if it	351	Likewise, $mode specifies the mode of the newly created file, if it
312	didn't exist and "O_CREAT" has been given, just like perl's	352	didn't exist and "O_CREAT" has been given, just like perl's
…		…
331	"O_APPEND"), the following POSIX and non-POSIX constants are	371	"O_APPEND"), the following POSIX and non-POSIX constants are
332	available (missing ones on your system are, as usual, 0):	372	available (missing ones on your system are, as usual, 0):
333		373
334	"O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",	374	"O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
335	"O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",	375	"O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
336	"O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT".	376	"O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", "O_TTY_INIT"
		377	and "O_ACCMODE".
337		378
338	aio_close $fh, $callback->($status)	379	aio_close $fh, $callback->($status)
339	Asynchronously close a file and call the callback with the result	380	Asynchronously close a file and call the callback with the result
340	code.	381	code.
341		382
…		…
371		412
372	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	413	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
373	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	414	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
374	Reads or writes $length bytes from or to the specified $fh and	415	Reads or writes $length bytes from or to the specified $fh and
375	$offset into the scalar given by $data and offset $dataoffset and	416	$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	417	calls the callback with the actual number of bytes transferred (or
377	error, just like the syscall).	418	-1 on error, just like the syscall).
378		419
379	"aio_read" will, like "sysread", shrink or grow the $data scalar to	420	"aio_read" will, like "sysread", shrink or grow the $data scalar to
380	offset plus the actual number of bytes read.	421	offset plus the actual number of bytes read.
381		422
382	If $offset is undefined, then the current file descriptor offset	423	If $offset is undefined, then the current file descriptor offset
…		…
439	As native sendfile syscalls (as practically any non-POSIX interface	480	As native sendfile syscalls (as practically any non-POSIX interface
440	hacked together in a hurry to improve benchmark numbers) tend to be	481	hacked together in a hurry to improve benchmark numbers) tend to be
441	rather buggy on many systems, this implementation tries to work	482	rather buggy on many systems, this implementation tries to work
442	around some known bugs in Linux and FreeBSD kernels (probably	483	around some known bugs in Linux and FreeBSD kernels (probably
443	others, too), but that might fail, so you really really should check	484	others, too), but that might fail, so you really really should check
444	the return value of "aio_sendfile" - fewre bytes than expected might	485	the return value of "aio_sendfile" - fewer bytes than expected might
445	have been transferred.	486	have been transferred.
446		487
447	aio_readahead $fh,$offset,$length, $callback->($retval)	488	aio_readahead $fh,$offset,$length, $callback->($retval)
448	"aio_readahead" populates the page cache with data from a file so	489	"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	490	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	494	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	495	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	496	read beyond the end of the file. The current file offset of the file
456	is left unchanged.	497	is left unchanged.
457		498
458	If that syscall doesn't exist (likely if your OS isn't Linux) it	499	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	500	will be emulated by simply reading the data, which would have a
460	similar effect.	501	similar effect.
461		502
462	aio_stat $fh_or_path, $callback->($status)	503	aio_stat $fh_or_path, $callback->($status)
463	aio_lstat $fh, $callback->($status)	504	aio_lstat $fh, $callback->($status)
464	Works like perl's "stat" or "lstat" in void context. The callback	505	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	506	The callback will be called after the stat and the results will be
466	using "stat _" or "-s _" etc...	507	available using "stat _" or "-s _" and other tests (with the
467		508	exception of "-B" and "-T").
468	The pathname passed to "aio_stat" must be absolute. See API NOTES,
469	above, for an explanation.
470		509
471	Currently, the stats are always 64-bit-stats, i.e. instead of	510	Currently, the stats are always 64-bit-stats, i.e. instead of
472	returning an error when stat'ing a large file, the results will be	511	returning an error when stat'ing a large file, the results will be
473	silently truncated unless perl itself is compiled with large file	512	silently truncated unless perl itself is compiled with large file
474	support.	513	support.
…		…
479	back on traditional behaviour).	518	back on traditional behaviour).
480		519
481	"S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",	520	"S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
482	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",	521	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
483	"IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".	522	"IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
		523
		524	To access higher resolution stat timestamps, see "SUBSECOND STAT
		525	TIME ACCESS".
484		526
485	Example: Print the length of /etc/passwd:	527	Example: Print the length of /etc/passwd:
486		528
487	aio_stat "/etc/passwd", sub {	529	aio_stat "/etc/passwd", sub {
488	$_[0] and die "stat failed: $!";	530	$_[0] and die "stat failed: $!";
…		…
530	namemax => 255,	572	namemax => 255,
531	frsize => 1024,	573	frsize => 1024,
532	fsid => 1810	574	fsid => 1810
533	}	575	}
534		576
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)	577	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
618	Works like perl's "utime" function (including the special case of	578	Works like perl's "utime" function (including the special case of
619	$atime and $mtime being undef). Fractional times are supported if	579	$atime and $mtime being undef). Fractional times are supported if
620	the underlying syscalls support them.	580	the underlying syscalls support them.
621		581
622	When called with a pathname, uses utimes(2) if available, otherwise	582	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	583	available, otherwise utime(2). If called on a file descriptor, uses
624	available, otherwise returns ENOSYS, so this is not portable.	584	futimens(2) or futimes(2) if available, otherwise returns ENOSYS, so
		585	this is not portable.
625		586
626	Examples:	587	Examples:
627		588
628	# set atime and mtime to current time (basically touch(1)):	589	# set atime and mtime to current time (basically touch(1)):
629	aio_utime "path", undef, undef;	590	aio_utime "path", undef, undef;
…		…
644		605
645	aio_truncate $fh_or_path, $offset, $callback->($status)	606	aio_truncate $fh_or_path, $offset, $callback->($status)
646	Works like truncate(2) or ftruncate(2).	607	Works like truncate(2) or ftruncate(2).
647		608
648	aio_allocate $fh, $mode, $offset, $len, $callback->($status)	609	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
649	Allocates or freed disk space according to the $mode argument. See	610	Allocates or frees disk space according to the $mode argument. See
650	the linux "fallocate" docuemntation for details.	611	the linux "fallocate" documentation for details.
651		612
652	$mode can currently be 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to	613	$mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
653	allocate space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE \|	614	space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE \|
654	IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.	615	IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
655		616
		617	IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range
		618	(without leaving a hole), "FALLOC_FL_ZERO_RANGE", to zero a range,
		619	"FALLOC_FL_INSERT_RANGE" to insert a range and
		620	"FALLOC_FL_UNSHARE_RANGE" to unshare shared blocks (see your
		621	fallocate(2) manpage).
		622
656	The file system block size used by "fallocate" is presumably the	623	The file system block size used by "fallocate" is presumably the
657	"f_bsize" returned by "statvfs".	624	"f_bsize" returned by "statvfs", but different filesystems and
		625	filetypes can dictate other limitations.
658		626
659	If "fallocate" isn't available or cannot be emulated (currently no	627	If "fallocate" isn't available or cannot be emulated (currently no
660	emulation will be attempted), passes -1 and sets $! to "ENOSYS".	628	emulation will be attempted), passes -1 and sets $! to "ENOSYS".
661		629
662	aio_chmod $fh_or_path, $mode, $callback->($status)	630	aio_chmod $fh_or_path, $mode, $callback->($status)
…		…
706		674
707	On systems that support the AIO::WD working directory abstraction	675	On systems that support the AIO::WD working directory abstraction
708	natively, the case "[$wd, "."]" as $srcpath is specialcased -	676	natively, the case "[$wd, "."]" as $srcpath is specialcased -
709	instead of failing, "rename" is called on the absolute path of $wd.	677	instead of failing, "rename" is called on the absolute path of $wd.
710		678
		679	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		680	Basically a version of "aio_rename" with an additional $flags
		681	argument. Calling this with "$flags=0" is the same as calling
		682	"aio_rename".
		683
		684	Non-zero flags are currently only supported on GNU/Linux systems
		685	that support renameat2. Other systems fail with "ENOSYS" in this
		686	case.
		687
		688	The following constants are available (missing ones are, as usual
		689	0), see renameat2(2) for details:
		690
		691	"IO::AIO::RENAME_NOREPLACE", "IO::AIO::RENAME_EXCHANGE" and
		692	"IO::AIO::RENAME_WHITEOUT".
		693
711	aio_mkdir $pathname, $mode, $callback->($status)	694	aio_mkdir $pathname, $mode, $callback->($status)
712	Asynchronously mkdir (create) a directory and call the callback with	695	Asynchronously mkdir (create) a directory and call the callback with
713	the result code. $mode will be modified by the umask at the time the	696	the result code. $mode will be modified by the umask at the time the
714	request is executed, so do not change your umask.	697	request is executed, so do not change your umask.
715		698
…		…
737	The flags are a combination of the following constants, ORed	720	The flags are a combination of the following constants, ORed
738	together (the flags will also be passed to the callback, possibly	721	together (the flags will also be passed to the callback, possibly
739	modified):	722	modified):
740		723
741	IO::AIO::READDIR_DENTS	724	IO::AIO::READDIR_DENTS
742	When this flag is off, then the callback gets an arrayref	725	Normally the callback gets an arrayref consisting of names only
743	consisting of names only (as with "aio_readdir"), otherwise it	726	(as with "aio_readdir"). If this flag is set, then the callback
744	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each	727	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
745	describing a single directory entry in more detail.	728	describing a single directory entry in more detail:
746		729
747	$name is the name of the entry.	730	$name is the name of the entry.
748		731
749	$type is one of the "IO::AIO::DT_xxx" constants:	732	$type is one of the "IO::AIO::DT_xxx" constants:
750		733
751	"IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",	734	"IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
752	"IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",	735	"IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
753	"IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".	736	"IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
754		737
755	"IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If	738	"IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
756	you need to know, you have to run stat yourself. Also, for speed	739	you need to know, you have to run stat yourself. Also, for
757	reasons, the $type scalars are read-only: you can not modify	740	speed/memory reasons, the $type scalars are read-only: you must
758	them.	741	not modify them.
759		742
760	$inode is the inode number (which might not be exact on systems	743	$inode is the inode number (which might not be exact on systems
761	with 64 bit inode numbers and 32 bit perls). This field has	744	with 64 bit inode numbers and 32 bit perls). This field has
762	unspecified content on systems that do not deliver the inode	745	unspecified content on systems that do not deliver the inode
763	information.	746	information.
…		…
775	of which names with short names are tried first.	758	of which names with short names are tried first.
776		759
777	IO::AIO::READDIR_STAT_ORDER	760	IO::AIO::READDIR_STAT_ORDER
778	When this flag is set, then the names will be returned in an	761	When this flag is set, then the names will be returned in an
779	order suitable for stat()'ing each one. That is, when you plan	762	order suitable for stat()'ing each one. That is, when you plan
780	to stat() all files in the given directory, then the returned	763	to stat() most or all files in the given directory, then the
781	order will likely be fastest.	764	returned order will likely be faster.
782		765
783	If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are	766	If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
784	specified, then the likely dirs come first, resulting in a less	767	specified, then the likely dirs come first, resulting in a less
785	optimal stat order.	768	optimal stat order for stat'ing all entries, but likely a more
		769	optimal order for finding subdirectories.
786		770
787	IO::AIO::READDIR_FOUND_UNKNOWN	771	IO::AIO::READDIR_FOUND_UNKNOWN
788	This flag should not be set when calling "aio_readdirx".	772	This flag should not be set when calling "aio_readdirx".
789	Instead, it is being set by "aio_readdirx", when any of the	773	Instead, it is being set by "aio_readdirx", when any of the
790	$type's found were "IO::AIO::DT_UNKNOWN". The absence of this	774	$type's found were "IO::AIO::DT_UNKNOWN". The absence of this
791	flag therefore indicates that all $type's are known, which can	775	flag therefore indicates that all $type's are known, which can
792	be used to speed up some algorithms.	776	be used to speed up some algorithms.
793		777
		778	aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		779	Opens, reads and closes the given file. The data is put into $data,
		780	which is resized as required.
		781
		782	If $offset is negative, then it is counted from the end of the file.
		783
		784	If $length is zero, then the remaining length of the file is used.
		785	Also, in this case, the same limitations to modifying $data apply as
		786	when IO::AIO::mmap is used, i.e. it must only be modified in-place
		787	with "substr". If the size of the file is known, specifying a
		788	non-zero $length results in a performance advantage.
		789
		790	This request is similar to the older "aio_load" request, but since
		791	it is a single request, it might be more efficient to use.
		792
		793	Example: load /etc/passwd into $passwd.
		794
		795	my $passwd;
		796	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		797	$_[0] >= 0
		798	or die "/etc/passwd: $!\n";
		799
		800	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		801	print $passwd;
		802	};
		803	IO::AIO::flush;
		804
794	aio_load $pathname, $data, $callback->($status)	805	aio_load $pathname, $data, $callback->($status)
795	This is a composite request that tries to fully load the given file	806	This is a composite request that tries to fully load the given file
796	into memory. Status is the same as with aio_read.	807	into memory. Status is the same as with aio_read.
		808
		809	Using "aio_slurp" might be more efficient, as it is a single
		810	request.
797		811
798	aio_copy $srcpath, $dstpath, $callback->($status)	812	aio_copy $srcpath, $dstpath, $callback->($status)
799	Try to copy the file (directories not supported as either source	813	Try to copy the file (directories not supported as either source
800	or destination) from $srcpath to $dstpath and call the callback with	814	or destination) from $srcpath to $dstpath and call the callback with
801	a status of 0 (ok) or -1 (error, see $!).	815	a status of 0 (ok) or -1 (error, see $!).
		816
		817	Existing destination files will be truncated.
802		818
803	This is a composite request that creates the destination file with	819	This is a composite request that creates the destination file with
804	mode 0200 and copies the contents of the source file into it using	820	mode 0200 and copies the contents of the source file into it using
805	"aio_sendfile", followed by restoring atime, mtime, access mode and	821	"aio_sendfile", followed by restoring atime, mtime, access mode and
806	uid/gid, in that order.	822	uid/gid, in that order.
…		…
823	to efficiently separate the entries of directory $path into two sets	839	to efficiently separate the entries of directory $path into two sets
824	of names, directories you can recurse into (directories), and ones	840	of names, directories you can recurse into (directories), and ones
825	you cannot recurse into (everything else, including symlinks to	841	you cannot recurse into (everything else, including symlinks to
826	directories).	842	directories).
827		843
828	"aio_scandir" is a composite request that creates of many sub	844	"aio_scandir" is a composite request that generates many sub
829	requests_ $maxreq specifies the maximum number of outstanding aio	845	requests. $maxreq specifies the maximum number of outstanding aio
830	requests that this function generates. If it is "<= 0", then a	846	requests that this function generates. If it is "<= 0", then a
831	suitable default will be chosen (currently 4).	847	suitable default will be chosen (currently 4).
832		848
833	On error, the callback is called without arguments, otherwise it	849	On error, the callback is called without arguments, otherwise it
834	receives two array-refs with path-relative entry names.	850	receives two array-refs with path-relative entry names.
…		…
881	Delete a directory tree starting (and including) $path, return the	897	Delete a directory tree starting (and including) $path, return the
882	status of the final "rmdir" only. This is a composite request that	898	status of the final "rmdir" only. This is a composite request that
883	uses "aio_scandir" to recurse into and rmdir directories, and unlink	899	uses "aio_scandir" to recurse into and rmdir directories, and unlink
884	everything else.	900	everything else.
885		901
		902	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		903	aio_ioctl $fh, $request, $buf, $callback->($status)
		904	These work just like the "fcntl" and "ioctl" built-in functions,
		905	except they execute asynchronously and pass the return value to the
		906	callback.
		907
		908	Both calls can be used for a lot of things, some of which make more
		909	sense to run asynchronously in their own thread, while some others
		910	make less sense. For example, calls that block waiting for external
		911	events, such as locking, will also lock down an I/O thread while it
		912	is waiting, which can deadlock the whole I/O system. At the same
		913	time, there might be no alternative to using a thread to wait.
		914
		915	So in general, you should only use these calls for things that do
		916	(filesystem) I/O, not for things that wait for other events
		917	(network, other processes), although if you are careful and know
		918	what you are doing, you still can.
		919
		920	The following constants are available and can be used for normal
		921	"ioctl" and "fcntl" as well (missing ones are, as usual 0):
		922
		923	"F_DUPFD_CLOEXEC",
		924
		925	"F_OFD_GETLK", "F_OFD_SETLK", "F_OFD_GETLKW",
		926
		927	"FIFREEZE", "FITHAW", "FITRIM", "FICLONE", "FICLONERANGE",
		928	"FIDEDUPERANGE".
		929
		930	"F_ADD_SEALS", "F_GET_SEALS", "F_SEAL_SEAL", "F_SEAL_SHRINK",
		931	"F_SEAL_GROW" and "F_SEAL_WRITE".
		932
		933	"FS_IOC_GETFLAGS", "FS_IOC_SETFLAGS", "FS_IOC_GETVERSION",
		934	"FS_IOC_SETVERSION", "FS_IOC_FIEMAP".
		935
		936	"FS_IOC_FSGETXATTR", "FS_IOC_FSSETXATTR",
		937	"FS_IOC_SET_ENCRYPTION_POLICY", "FS_IOC_GET_ENCRYPTION_PWSALT",
		938	"FS_IOC_GET_ENCRYPTION_POLICY", "FS_KEY_DESCRIPTOR_SIZE".
		939
		940	"FS_SECRM_FL", "FS_UNRM_FL", "FS_COMPR_FL", "FS_SYNC_FL",
		941	"FS_IMMUTABLE_FL", "FS_APPEND_FL", "FS_NODUMP_FL", "FS_NOATIME_FL",
		942	"FS_DIRTY_FL", "FS_COMPRBLK_FL", "FS_NOCOMP_FL", "FS_ENCRYPT_FL",
		943	"FS_BTREE_FL", "FS_INDEX_FL", "FS_JOURNAL_DATA_FL", "FS_NOTAIL_FL",
		944	"FS_DIRSYNC_FL", "FS_TOPDIR_FL", "FS_FL_USER_MODIFIABLE".
		945
		946	"FS_XFLAG_REALTIME", "FS_XFLAG_PREALLOC", "FS_XFLAG_IMMUTABLE",
		947	"FS_XFLAG_APPEND", "FS_XFLAG_SYNC", "FS_XFLAG_NOATIME",
		948	"FS_XFLAG_NODUMP", "FS_XFLAG_RTINHERIT", "FS_XFLAG_PROJINHERIT",
		949	"FS_XFLAG_NOSYMLINKS", "FS_XFLAG_EXTSIZE", "FS_XFLAG_EXTSZINHERIT",
		950	"FS_XFLAG_NODEFRAG", "FS_XFLAG_FILESTREAM", "FS_XFLAG_DAX",
		951	"FS_XFLAG_HASATTR",
		952
		953	"BLKROSET", "BLKROGET", "BLKRRPART", "BLKGETSIZE", "BLKFLSBUF",
		954	"BLKRASET", "BLKRAGET", "BLKFRASET", "BLKFRAGET", "BLKSECTSET",
		955	"BLKSECTGET", "BLKSSZGET", "BLKBSZGET", "BLKBSZSET", "BLKGETSIZE64",
		956
886	aio_sync $callback->($status)	957	aio_sync $callback->($status)
887	Asynchronously call sync and call the callback when finished.	958	Asynchronously call sync and call the callback when finished.
888		959
889	aio_fsync $fh, $callback->($status)	960	aio_fsync $fh, $callback->($status)
890	Asynchronously call fsync on the given filehandle and call the	961	Asynchronously call fsync on the given filehandle and call the
…		…
926	Future versions of this function might fall back to other methods	997	Future versions of this function might fall back to other methods
927	when "fsync" on the directory fails (such as calling "sync").	998	when "fsync" on the directory fails (such as calling "sync").
928		999
929	Passes 0 when everything went ok, and -1 on error.	1000	Passes 0 when everything went ok, and -1 on error.
930		1001
931	aio_msync $scalar, $offset = 0, $length = undef, flags = 0,	1002	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
932	$callback->($status)	1003	$callback->($status)
933	This is a rather advanced IO::AIO call, which only works on	1004	This is a rather advanced IO::AIO call, which only works on
934	mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it	1005	mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
935	also works on data scalars managed by the Sys::Mmap or Mmap modules,	1006	also works on data scalars managed by the Sys::Mmap or Mmap modules,
936	note that the scalar must only be modified in-place while an aio	1007	note that the scalar must only be modified in-place while an aio
…		…
938		1009
939	It calls the "msync" function of your OS, if available, with the	1010	It calls the "msync" function of your OS, if available, with the
940	memory area starting at $offset in the string and ending $length	1011	memory area starting at $offset in the string and ending $length
941	bytes later. If $length is negative, counts from the end, and if	1012	bytes later. If $length is negative, counts from the end, and if
942	$length is "undef", then it goes till the end of the string. The	1013	$length is "undef", then it goes till the end of the string. The
943	flags can be a combination of "IO::AIO::MS_ASYNC",	1014	flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus
944	"IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".	1015	an optional "IO::AIO::MS_INVALIDATE".
945		1016
946	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,	1017	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
947	$callback->($status)	1018	$callback->($status)
948	This is a rather advanced IO::AIO call, which works best on	1019	This is a rather advanced IO::AIO call, which works best on
949	mmap(2)ed scalars.	1020	mmap(2)ed scalars.
…		…
980	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;	1051	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
981	aio_mlock $data; # mlock in background	1052	aio_mlock $data; # mlock in background
982		1053
983	aio_mlockall $flags, $callback->($status)	1054	aio_mlockall $flags, $callback->($status)
984	Calls the "mlockall" function with the given $flags (a combination	1055	Calls the "mlockall" function with the given $flags (a combination
985	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").	1056	of "IO::AIO::MCL_CURRENT", "IO::AIO::MCL_FUTURE" and
		1057	"IO::AIO::MCL_ONFAULT").
986		1058
987	On systems that do not implement "mlockall", this function returns	1059	On systems that do not implement "mlockall", this function returns
988	-1 and sets errno to "ENOSYS".	1060	-1 and sets errno to "ENOSYS". Similarly, flag combinations not
		1061	supported by the system result in a return value of -1 with errno
		1062	being set to "EINVAL".
989		1063
990	Note that the corresponding "munlockall" is synchronous and is	1064	Note that the corresponding "munlockall" is synchronous and is
991	documented under "MISCELLANEOUS FUNCTIONS".	1065	documented under "MISCELLANEOUS FUNCTIONS".
992		1066
993	Example: asynchronously lock all current and future pages into	1067	Example: asynchronously lock all current and future pages into
…		…
1035	"IO::AIO::FIEMAP_EXTENT_DATA_INLINE",	1109	"IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1036	"IO::AIO::FIEMAP_EXTENT_DATA_TAIL",	1110	"IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1037	"IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"	1111	"IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1038	or "IO::AIO::FIEMAP_EXTENT_SHARED".	1112	or "IO::AIO::FIEMAP_EXTENT_SHARED".
1039		1113
1040	At the time of this writing (Linux 3.2), this requets is unreliable	1114	At the time of this writing (Linux 3.2), this request is unreliable
1041	unless $count is "undef", as the kernel has all sorts of bugs	1115	unless $count is "undef", as the kernel has all sorts of bugs
1042	preventing it to return all extents of a range for files with large	1116	preventing it to return all extents of a range for files with a
1043	number of extents. The code works around all these issues if $count	1117	large number of extents. The code (only) works around all these
1044	is undef.	1118	issues if $count is "undef".
1045		1119
1046	aio_group $callback->(...)	1120	aio_group $callback->(...)
1047	This is a very special aio request: Instead of doing something, it	1121	This is a very special aio request: Instead of doing something, it
1048	is a container for other aio requests, which is useful if you want	1122	is a container for other aio requests, which is useful if you want
1049	to bundle many requests into a single, composite, request with a	1123	to bundle many requests into a single, composite, request with a
…		…
1129	aio_stat [$etcdir, "passwd"], sub {	1203	aio_stat [$etcdir, "passwd"], sub {
1130	# yay	1204	# yay
1131	};	1205	};
1132	};	1206	};
1133		1207
1134	That "aio_wd" is a request and not a normal function shows that creating	1208	The fact that "aio_wd" is a request and not a normal function shows that
1135	an IO::AIO::WD object is itself a potentially blocking operation, which	1209	creating an IO::AIO::WD object is itself a potentially blocking
1136	is why it is done asynchronously.	1210	operation, which is why it is done asynchronously.
1137		1211
1138	To stat the directory obtained with "aio_wd" above, one could write	1212	To stat the directory obtained with "aio_wd" above, one could write
1139	either of the following three request calls:	1213	either of the following three request calls:
1140		1214
1141	aio_lstat "/etc" , sub { ... # pathname as normal string	1215	aio_lstat "/etc" , sub { ... # pathname as normal string
…		…
1158	There are some caveats: when directories get renamed (or deleted), the	1232	There are some caveats: when directories get renamed (or deleted), the
1159	pathname string doesn't change, so will point to the new directory (or	1233	pathname string doesn't change, so will point to the new directory (or
1160	nowhere at all), while the directory fd, if available on the system,	1234	nowhere at all), while the directory fd, if available on the system,
1161	will still point to the original directory. Most functions accepting a	1235	will still point to the original directory. Most functions accepting a
1162	pathname will use the directory fd on newer systems, and the string on	1236	pathname will use the directory fd on newer systems, and the string on
1163	older systems. Some functions (such as realpath) will always rely on the	1237	older systems. Some functions (such as "aio_realpath") will always rely
1164	string form of the pathname.	1238	on the string form of the pathname.
1165		1239
1166	So this functionality is mainly useful to get some protection against	1240	So this functionality is mainly useful to get some protection against
1167	"chdir", to easily get an absolute path out of a relative path for	1241	"chdir", to easily get an absolute path out of a relative path for
1168	future reference, and to speed up doing many operations in the same	1242	future reference, and to speed up doing many operations in the same
1169	directory (e.g. when stat'ing all files in a directory).	1243	directory (e.g. when stat'ing all files in a directory).
…		…
1181	Since passing "undef" as working directory component of a pathname	1255	Since passing "undef" as working directory component of a pathname
1182	fails the request with "ENOENT", there is often no need for error	1256	fails the request with "ENOENT", there is often no need for error
1183	checking in the "aio_wd" callback, as future requests using the	1257	checking in the "aio_wd" callback, as future requests using the
1184	value will fail in the expected way.	1258	value will fail in the expected way.
1185		1259
1186	If this call isn't available because your OS lacks it or it couldn't
1187	be detected, it will be emulated by calling "fsync" instead.
1188
1189	IO::AIO::CWD	1260	IO::AIO::CWD
1190	This is a compiletime constant (object) that represents the process	1261	This is a compile time constant (object) that represents the process
1191	current working directory.	1262	current working directory.
1192		1263
1193	Specifying this object as working directory object for a pathname is	1264	Specifying this object as working directory object for a pathname is
1194	as if the pathname would be specified directly, without a directory	1265	as if the pathname would be specified directly, without a directory
1195	object. For example, these calls are functionally identical:	1266	object. For example, these calls are functionally identical:
…		…
1420	Strictly equivalent to:	1491	Strictly equivalent to:
1421		1492
1422	IO::AIO::poll_wait, IO::AIO::poll_cb	1493	IO::AIO::poll_wait, IO::AIO::poll_cb
1423	while IO::AIO::nreqs;	1494	while IO::AIO::nreqs;
1424		1495
		1496	This function can be useful at program aborts, to make sure
		1497	outstanding I/O has been done ("IO::AIO" uses an "END" block which
		1498	already calls this function on normal exits), or when you are merely
		1499	using "IO::AIO" for its more advanced functions, rather than for
		1500	async I/O, e.g.:
		1501
		1502	my ($dirs, $nondirs);
		1503	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1504	IO::AIO::flush;
		1505	# $dirs, $nondirs are now set
		1506
1425	IO::AIO::max_poll_reqs $nreqs	1507	IO::AIO::max_poll_reqs $nreqs
1426	IO::AIO::max_poll_time $seconds	1508	IO::AIO::max_poll_time $seconds
1427	These set the maximum number of requests (default 0, meaning	1509	These set the maximum number of requests (default 0, meaning
1428	infinity) that are being processed by "IO::AIO::poll_cb" in one	1510	infinity) that are being processed by "IO::AIO::poll_cb" in one
1429	call, respectively the maximum amount of time (default 0, meaning	1511	call, respectively the maximum amount of time (default 0, meaning
…		…
1518	no longer exceeded.	1600	no longer exceeded.
1519		1601
1520	In other words, this setting does not enforce a queue limit, but can	1602	In other words, this setting does not enforce a queue limit, but can
1521	be used to make poll functions block if the limit is exceeded.	1603	be used to make poll functions block if the limit is exceeded.
1522		1604
1523	This is a very bad function to use in interactive programs because	1605	This is a bad function to use in interactive programs because it
1524	it blocks, and a bad way to reduce concurrency because it is	1606	blocks, and a bad way to reduce concurrency because it is inexact.
1525	inexact: Better use an "aio_group" together with a feed callback.	1607	If you need to issue many requests without being able to call a poll
		1608	function on demand, it is better to use an "aio_group" together with
		1609	a feed callback.
1526		1610
1527	It's main use is in scripts without an event loop - when you want to	1611	Its main use is in scripts without an event loop - when you want to
1528	stat a lot of files, you can write somehting like this:	1612	stat a lot of files, you can write something like this:
1529		1613
1530	IO::AIO::max_outstanding 32;	1614	IO::AIO::max_outstanding 32;
1531		1615
1532	for my $path (...) {	1616	for my $path (...) {
1533	aio_stat $path , ...;	1617	aio_stat $path , ...;
…		…
1535	}	1619	}
1536		1620
1537	IO::AIO::flush;	1621	IO::AIO::flush;
1538		1622
1539	The call to "poll_cb" inside the loop will normally return	1623	The call to "poll_cb" inside the loop will normally return
1540	instantly, but as soon as more thna 32 reqeusts are in-flight, it	1624	instantly, allowing the loop to progress, but as soon as more than
1541	will block until some requests have been handled. This keeps the	1625	32 requests are in-flight, it will block until some requests have
1542	loop from pushing a large number of "aio_stat" requests onto the	1626	been handled. This keeps the loop from pushing a large number of
1543	queue.	1627	"aio_stat" requests onto the queue (which, with many paths to stat,
		1628	can use up a lot of memory).
1544		1629
1545	The default value for "max_outstanding" is very large, so there is	1630	The default value for "max_outstanding" is very large, so there is
1546	no practical limit on the number of outstanding requests.	1631	no practical limit on the number of outstanding requests.
1547		1632
1548	STATISTICAL INFORMATION	1633	STATISTICAL INFORMATION
…		…
1562		1647
1563	IO::AIO::npending	1648	IO::AIO::npending
1564	Returns the number of requests currently in the pending state	1649	Returns the number of requests currently in the pending state
1565	(executed, but not yet processed by poll_cb).	1650	(executed, but not yet processed by poll_cb).
1566		1651
		1652	SUBSECOND STAT TIME ACCESS
		1653	Both "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" functions can
		1654	generally find access/modification and change times with subsecond time
		1655	accuracy of the system supports it, but perl's built-in functions only
		1656	return the integer part.
		1657
		1658	The following functions return the timestamps of the most recent stat
		1659	with subsecond precision on most systems and work both after
		1660	"aio_stat"/"aio_lstat" and perl's "stat"/"lstat" calls. Their return
		1661	value is only meaningful after a successful "stat"/"lstat" call, or
		1662	during/after a successful "aio_stat"/"aio_lstat" callback.
		1663
		1664	This is similar to the Time::HiRes "stat" functions, but can return full
		1665	resolution without rounding and work with standard perl "stat",
		1666	alleviating the need to call the special "Time::HiRes" functions, which
		1667	do not act like their perl counterparts.
		1668
		1669	On operating systems or file systems where subsecond time resolution is
		1670	not supported or could not be detected, a fractional part of 0 is
		1671	returned, so it is always safe to call these functions.
		1672
		1673	$seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime,
		1674	IO::AIO::st_btime
		1675	Return the access, modication, change or birth time, respectively,
		1676	including fractional part. Due to the limited precision of floating
		1677	point, the accuracy on most platforms is only a bit better than
		1678	milliseconds for times around now - see the nsec function family,
		1679	below, for full accuracy.
		1680
		1681	File birth time is only available when the OS and perl support it
		1682	(on FreeBSD and NetBSD at the time of this writing, although support
		1683	is adaptive, so if your OS/perl gains support, IO::AIO can take
		1684	advantage of it). On systems where it isn't available, 0 is
		1685	currently returned, but this might change to "undef" in a future
		1686	version.
		1687
		1688	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		1689	Returns access, modification, change and birth time all in one go,
		1690	and maybe more times in the future version.
		1691
		1692	$nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec,
		1693	IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		1694	Return the fractional access, modifcation, change or birth time, in
		1695	nanoseconds, as an integer in the range 0 to 999999999.
		1696
		1697	Note that no accessors are provided for access, modification and
		1698	change times - you need to get those from "stat _" if required ("int
		1699	IO::AIO::st_atime" and so on will not generally give you the
		1700	correct value).
		1701
		1702	$seconds = IO::AIO::st_btimesec
		1703	The (integral) seconds part of the file birth time, if available.
		1704
		1705	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		1706	Like the functions above, but returns all four times in one go (and
		1707	maybe more in future versions).
		1708
		1709	$counter = IO::AIO::st_gen
		1710	Returns the generation counter (in practice this is just a random
		1711	number) of the file. This is only available on platforms which have
		1712	this member in their "struct stat" (most BSDs at the time of this
		1713	writing) and generally only to the root usert. If unsupported, 0 is
		1714	returned, but this might change to "undef" in a future version.
		1715
		1716	Example: print the high resolution modification time of /etc, using
		1717	"stat", and "IO::AIO::aio_stat".
		1718
		1719	if (stat "/etc") {
		1720	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		1721	}
		1722
		1723	IO::AIO::aio_stat "/etc", sub {
		1724	$_[0]
		1725	and return;
		1726
		1727	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		1728	};
		1729
		1730	IO::AIO::flush;
		1731
		1732	Output of the awbove on my system, showing reduced and full accuracy:
		1733
		1734	stat(/etc) mtime: 1534043702.020808
		1735	aio_stat(/etc) mtime: 1534043702.020807792
		1736
1567	MISCELLANEOUS FUNCTIONS	1737	MISCELLANEOUS FUNCTIONS
1568	IO::AIO implements some functions that might be useful, but are not	1738	IO::AIO implements some functions that are useful when you want to use
1569	asynchronous.	1739	some "Advanced I/O" function not available to in Perl, without going the
		1740	"Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
		1741	counterpart.
		1742
		1743	$retval = IO::AIO::fexecve $fh, $argv, $envp
		1744	A more-or-less direct equivalent to the POSIX "fexecve" functions,
		1745	which allows you to specify the program to be executed via a file
		1746	descriptor (or handle). Returns -1 and sets errno to "ENOSYS" if not
		1747	available.
		1748
		1749	$retval = IO::AIO::mount $special, $path, $fstype, $flags = 0, $data =
		1750	undef
		1751	Calls the GNU/Linux mount syscall with the given arguments. All
		1752	except $flags are strings, and if $data is "undef", a "NULL" will be
		1753	passed.
		1754
		1755	The following values for $flags are available:
		1756
		1757	"IO::AIO::MS_RDONLY", "IO::AIO::MS_NOSUID", "IO::AIO::MS_NODEV",
		1758	"IO::AIO::MS_NOEXEC", "IO::AIO::MS_SYNCHRONOUS",
		1759	"IO::AIO::MS_REMOUNT", "IO::AIO::MS_MANDLOCK",
		1760	"IO::AIO::MS_DIRSYNC", "IO::AIO::MS_NOATIME",
		1761	"IO::AIO::MS_NODIRATIME", "IO::AIO::MS_BIND", "IO::AIO::MS_MOVE",
		1762	"IO::AIO::MS_REC", "IO::AIO::MS_SILENT", "IO::AIO::MS_POSIXACL",
		1763	"IO::AIO::MS_UNBINDABLE", "IO::AIO::MS_PRIVATE",
		1764	"IO::AIO::MS_SLAVE", "IO::AIO::MS_SHARED", "IO::AIO::MS_RELATIME",
		1765	"IO::AIO::MS_KERNMOUNT", "IO::AIO::MS_I_VERSION",
		1766	"IO::AIO::MS_STRICTATIME", "IO::AIO::MS_LAZYTIME",
		1767	"IO::AIO::MS_ACTIVE", "IO::AIO::MS_NOUSER", "IO::AIO::MS_RMT_MASK",
		1768	"IO::AIO::MS_MGC_VAL" and "IO::AIO::MS_MGC_MSK".
		1769
		1770	$retval = IO::AIO::umount $path, $flags = 0
		1771	Invokes the GNU/Linux "umount" or "umount2" syscalls. Always calls
		1772	"umount" if $flags is 0, otherwqise always tries to call "umount2".
		1773
		1774	The following $flags are available:
		1775
		1776	"IO::AIO::MNT_FORCE", "IO::AIO::MNT_DETACH", "IO::AIO::MNT_EXPIRE"
		1777	and "IO::AIO::UMOUNT_NOFOLLOW".
		1778
		1779	$numfd = IO::AIO::get_fdlimit
		1780	Tries to find the current file descriptor limit and returns it, or
		1781	"undef" and sets $! in case of an error. The limit is one larger
		1782	than the highest valid file descriptor number.
		1783
		1784	IO::AIO::min_fdlimit [$numfd]
		1785	Try to increase the current file descriptor limit(s) to at least
		1786	$numfd by changing the soft or hard file descriptor resource limit.
		1787	If $numfd is missing, it will try to set a very high limit, although
		1788	this is not recommended when you know the actual minimum that you
		1789	require.
		1790
		1791	If the limit cannot be raised enough, the function makes a
		1792	best-effort attempt to increase the limit as much as possible, using
		1793	various tricks, while still failing. You can query the resulting
		1794	limit using "IO::AIO::get_fdlimit".
		1795
		1796	If an error occurs, returns "undef" and sets $!, otherwise returns
		1797	true.
1570		1798
1571	IO::AIO::sendfile $ofh, $ifh, $offset, $count	1799	IO::AIO::sendfile $ofh, $ifh, $offset, $count
1572	Calls the "eio_sendfile_sync" function, which is like	1800	Calls the "eio_sendfile_sync" function, which is like
1573	"aio_sendfile", but is blocking (this makes most sense if you know	1801	"aio_sendfile", but is blocking (this makes most sense if you know
1574	the input data is likely cached already and the output filehandle is	1802	the input data is likely cached already and the output filehandle is
…		…
1591	details). The following advice constants are available:	1819	details). The following advice constants are available:
1592	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",	1820	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1593	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",	1821	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1594	"IO::AIO::MADV_DONTNEED".	1822	"IO::AIO::MADV_DONTNEED".
1595		1823
		1824	If $offset is negative, counts from the end. If $length is negative,
		1825	the remaining length of the $scalar is used. If possible, $length
		1826	will be reduced to fit into the $scalar.
		1827
1596	On systems that do not implement "posix_madvise", this function	1828	On systems that do not implement "posix_madvise", this function
1597	returns ENOSYS, otherwise the return value of "posix_madvise".	1829	returns ENOSYS, otherwise the return value of "posix_madvise".
1598		1830
1599	IO::AIO::mprotect $scalar, $offset, $len, $protect	1831	IO::AIO::mprotect $scalar, $offset, $len, $protect
1600	Simply calls the "mprotect" function on the preferably AIO::mmap'ed	1832	Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1601	$scalar (see its manpage for details). The following protect	1833	$scalar (see its manpage for details). The following protect
1602	constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",	1834	constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1603	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".	1835	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1604		1836
		1837	If $offset is negative, counts from the end. If $length is negative,
		1838	the remaining length of the $scalar is used. If possible, $length
		1839	will be reduced to fit into the $scalar.
		1840
1605	On systems that do not implement "mprotect", this function returns	1841	On systems that do not implement "mprotect", this function returns
1606	ENOSYS, otherwise the return value of "mprotect".	1842	ENOSYS, otherwise the return value of "mprotect".
1607		1843
1608	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	1844	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1609	Memory-maps a file (or anonymous memory range) and attaches it to	1845	Memory-maps a file (or anonymous memory range) and attaches it to
1610	the given $scalar, which will act like a string scalar. Returns true	1846	the given $scalar, which will act like a string scalar. Returns true
1611	on success, and false otherwise.	1847	on success, and false otherwise.
1612		1848
		1849	The scalar must exist, but its contents do not matter - this means
		1850	you cannot use a nonexistant array or hash element. When in doubt,
		1851	"undef" the scalar first.
		1852
1613	The only operations allowed on the scalar are "substr"/"vec" that	1853	The only operations allowed on the mmapped scalar are
1614	don't change the string length, and most read-only operations such	1854	"substr"/"vec", which don't change the string length, and most
1615	as copying it or searching it with regexes and so on.	1855	read-only operations such as copying it or searching it with regexes
		1856	and so on.
1616		1857
1617	Anything else is unsafe and will, at best, result in memory leaks.	1858	Anything else is unsafe and will, at best, result in memory leaks.
1618		1859
1619	The memory map associated with the $scalar is automatically removed	1860	The memory map associated with the $scalar is automatically removed
1620	when the $scalar is destroyed, or when the "IO::AIO::mmap" or	1861	when the $scalar is undef'd or destroyed, or when the
1621	"IO::AIO::munmap" functions are called.	1862	"IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1622		1863
1623	This calls the "mmap"(2) function internally. See your system's	1864	This calls the "mmap"(2) function internally. See your system's
1624	manual page for details on the $length, $prot and $flags parameters.	1865	manual page for details on the $length, $prot and $flags parameters.
1625		1866
1626	The $length must be larger than zero and smaller than the actual	1867	The $length must be larger than zero and smaller than the actual
…		…
1630	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or	1871	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1631	"IO::AIO::PROT_WRITE",	1872	"IO::AIO::PROT_WRITE",
1632		1873
1633	$flags can be a combination of "IO::AIO::MAP_SHARED" or	1874	$flags can be a combination of "IO::AIO::MAP_SHARED" or
1634	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when	1875	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1635	not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"	1876	not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1636	(which is set to "MAP_ANON" if your system only provides this	1877	"MAP_ANON" if your system only provides this constant),
		1878	"IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1637	constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",	1879	"IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1638	"IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or	1880	"IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1639	"IO::AIO::MAP_NONBLOCK"	1881	"IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_STACK",
		1882	"IO::AIO::MAP_FIXED_NOREPLACE", "IO::AIO::MAP_SHARED_VALIDATE",
		1883	"IO::AIO::MAP_SYNC" or "IO::AIO::MAP_UNINITIALIZED".
1640		1884
1641	If $fh is "undef", then a file descriptor of -1 is passed.	1885	If $fh is "undef", then a file descriptor of -1 is passed.
1642		1886
1643	$offset is the offset from the start of the file - it generally must	1887	$offset is the offset from the start of the file - it generally must
1644	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.	1888	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
…		…
1656		1900
1657	my $fast_md5 = md5 $data;	1901	my $fast_md5 = md5 $data;
1658		1902
1659	IO::AIO::munmap $scalar	1903	IO::AIO::munmap $scalar
1660	Removes a previous mmap and undefines the $scalar.	1904	Removes a previous mmap and undefines the $scalar.
		1905
		1906	IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[,
		1907	$new_address = 0]
		1908	Calls the Linux-specific mremap(2) system call. The $scalar must
		1909	have been mapped by "IO::AIO::mmap", and $flags must currently
		1910	either be 0 or "IO::AIO::MREMAP_MAYMOVE".
		1911
		1912	Returns true if successful, and false otherwise. If the underlying
		1913	mmapped region has changed address, then the true value has the
		1914	numerical value 1, otherwise it has the numerical value 0:
		1915
		1916	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		1917	or die "mremap: $!";
		1918
		1919	if ($success*1) {
		1920	warn "scalar has chanegd address in memory\n";
		1921	}
		1922
		1923	"IO::AIO::MREMAP_FIXED" and the $new_address argument are currently
		1924	implemented, but not supported and might go away in a future
		1925	version.
		1926
		1927	On systems where this call is not supported or is not emulated, this
		1928	call returns falls and sets $! to "ENOSYS".
		1929
		1930	IO::AIO::mlockall $flags
		1931	Calls the "eio_mlockall_sync" function, which is like
		1932	"aio_mlockall", but is blocking.
1661		1933
1662	IO::AIO::munlock $scalar, $offset = 0, $length = undef	1934	IO::AIO::munlock $scalar, $offset = 0, $length = undef
1663	Calls the "munlock" function, undoing the effects of a previous	1935	Calls the "munlock" function, undoing the effects of a previous
1664	"aio_mlock" call (see its description for details).	1936	"aio_mlock" call (see its description for details).
1665		1937
1666	IO::AIO::munlockall	1938	IO::AIO::munlockall
1667	Calls the "munlockall" function.	1939	Calls the "munlockall" function.
1668		1940
1669	On systems that do not implement "munlockall", this function returns	1941	On systems that do not implement "munlockall", this function returns
1670	ENOSYS, otherwise the return value of "munlockall".	1942	ENOSYS, otherwise the return value of "munlockall".
		1943
		1944	$fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		1945	Uses the GNU/Linux accept4(2) syscall, if available, to accept a
		1946	socket and return the new file handle on success, or sets $! and
		1947	returns "undef" on error.
		1948
		1949	The remote name of the new socket will be stored in $sockaddr, which
		1950	will be extended to allow for at least $sockaddr_maxlen octets. If
		1951	the socket name does not fit into $sockaddr_maxlen octets, this is
		1952	signaled by returning a longer string in $sockaddr, which might or
		1953	might not be truncated.
		1954
		1955	To accept name-less sockets, use "undef" for $sockaddr and 0 for
		1956	$sockaddr_maxlen.
		1957
		1958	The main reasons to use this syscall rather than portable accept(2)
		1959	are that you can specify "SOCK_NONBLOCK" and/or "SOCK_CLOEXEC" flags
		1960	and you can accept name-less sockets by specifying 0 for
		1961	$sockaddr_maxlen, which is sadly not possible with perl's interface
		1962	to "accept".
1671		1963
1672	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags	1964	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1673	Calls the GNU/Linux splice(2) syscall, if available. If $r_off or	1965	Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1674	$w_off are "undef", then "NULL" is passed for these, otherwise they	1966	$w_off are "undef", then "NULL" is passed for these, otherwise they
1675	should be the file offset.	1967	should be the file offset.
…		…
1682	"IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".	1974	"IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1683		1975
1684	See the splice(2) manpage for details.	1976	See the splice(2) manpage for details.
1685		1977
1686	IO::AIO::tee $r_fh, $w_fh, $length, $flags	1978	IO::AIO::tee $r_fh, $w_fh, $length, $flags
1687	Calls the GNU/Linux tee(2) syscall, see it's manpage and the	1979	Calls the GNU/Linux tee(2) syscall, see its manpage and the
1688	description for "IO::AIO::splice" above for details.	1980	description for "IO::AIO::splice" above for details.
		1981
		1982	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		1983	Attempts to query or change the pipe buffer size. Obviously works
		1984	only on pipes, and currently works only on GNU/Linux systems, and
		1985	fails with -1/"ENOSYS" everywhere else. If anybody knows how to
		1986	influence pipe buffer size on other systems, drop me a note.
		1987
		1988	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		1989	This is a direct interface to the Linux pipe2(2) system call. If
		1990	$flags is missing or 0, then this should be the same as a call to
		1991	perl's built-in "pipe" function and create a new pipe, and works on
		1992	systems that lack the pipe2 syscall. On win32, this case invokes
		1993	"_pipe (..., 4096, O_BINARY)".
		1994
		1995	If $flags is non-zero, it tries to invoke the pipe2 system call with
		1996	the given flags (Linux 2.6.27, glibc 2.9).
		1997
		1998	On success, the read and write file handles are returned.
		1999
		2000	On error, nothing will be returned. If the pipe2 syscall is missing
		2001	and $flags is non-zero, fails with "ENOSYS".
		2002
		2003	Please refer to pipe2(2) for more info on the $flags, but at the
		2004	time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
		2005	and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
		2006	supported.
		2007
		2008	Example: create a pipe race-free w.r.t. threads and fork:
		2009
		2010	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2011	or die "pipe2: $!\n";
		2012
		2013	$fh = IO::AIO::memfd_create $pathname[, $flags]
		2014	This is a direct interface to the Linux memfd_create(2) system call.
		2015	The (unhelpful) default for $flags is 0, but your default should be
		2016	"IO::AIO::MFD_CLOEXEC".
		2017
		2018	On success, the new memfd filehandle is returned, otherwise returns
		2019	"undef". If the memfd_create syscall is missing, fails with
		2020	"ENOSYS".
		2021
		2022	Please refer to memfd_create(2) for more info on this call.
		2023
		2024	The following $flags values are available: "IO::AIO::MFD_CLOEXEC",
		2025	"IO::AIO::MFD_ALLOW_SEALING", "IO::AIO::MFD_HUGETLB",
		2026	"IO::AIO::MFD_HUGETLB_2MB" and "IO::AIO::MFD_HUGETLB_1GB".
		2027
		2028	Example: create a new memfd.
		2029
		2030	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2031	or die "memfd_create: $!\n";
		2032
		2033	$fh = IO::AIO::pidfd_open $pid[, $flags]
		2034	This is an interface to the Linux pidfd_open(2) system call. The
		2035	default for $flags is 0.
		2036
		2037	On success, a new pidfd filehandle is returned (that is already set
		2038	to close-on-exec), otherwise returns "undef". If the syscall is
		2039	missing, fails with "ENOSYS".
		2040
		2041	Example: open pid 6341 as pidfd.
		2042
		2043	my $fh = IO::AIO::pidfd_open 6341
		2044	or die "pidfd_open: $!\n";
		2045
		2046	$status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[,
		2047	$flags]]
		2048	This is an interface to the Linux pidfd_send_signal system call. The
		2049	default for $siginfo is "undef" and the default for $flags is 0.
		2050
		2051	Returns the system call status. If the syscall is missing, fails
		2052	with "ENOSYS".
		2053
		2054	When specified, $siginfo must be a reference to a hash with one or
		2055	more of the following members:
		2056
		2057	code - the "si_code" member
		2058	pid - the "si_pid" member
		2059	uid - the "si_uid" member
		2060	value_int - the "si_value.sival_int" member
		2061	value_ptr - the "si_value.sival_ptr" member, specified as an integer
		2062
		2063	Example: send a SIGKILL to the specified process.
		2064
		2065	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
		2066	and die "pidfd_send_signal: $!\n";
		2067
		2068	Example: send a SIGKILL to the specified process with extra data.
		2069
		2070	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
		2071	and die "pidfd_send_signal: $!\n";
		2072
		2073	$fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		2074	This is an interface to the Linux pidfd_getfd system call. The
		2075	default for $flags is 0.
		2076
		2077	On success, returns a dup'ed copy of the target file descriptor
		2078	(specified as an integer) returned (that is already set to
		2079	close-on-exec), otherwise returns "undef". If the syscall is
		2080	missing, fails with "ENOSYS".
		2081
		2082	Example: get a copy of standard error of another process and print
		2083	soemthing to it.
		2084
		2085	my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
		2086	or die "pidfd_getfd: $!\n";
		2087	print $errfh "stderr\n";
		2088
		2089	$fh = IO::AIO::eventfd [$initval, [$flags]]
		2090	This is a direct interface to the Linux eventfd(2) system call. The
		2091	(unhelpful) defaults for $initval and $flags are 0 for both.
		2092
		2093	On success, the new eventfd filehandle is returned, otherwise
		2094	returns "undef". If the eventfd syscall is missing, fails with
		2095	"ENOSYS".
		2096
		2097	Please refer to eventfd(2) for more info on this call.
		2098
		2099	The following symbol flag values are available:
		2100	"IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
		2101	"IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
		2102
		2103	Example: create a new eventfd filehandle:
		2104
		2105	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2106	or die "eventfd: $!\n";
		2107
		2108	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		2109	This is a direct interface to the Linux timerfd_create(2) system
		2110	call. The (unhelpful) default for $flags is 0, but your default
		2111	should be "IO::AIO::TFD_CLOEXEC".
		2112
		2113	On success, the new timerfd filehandle is returned, otherwise
		2114	returns "undef". If the timerfd_create syscall is missing, fails
		2115	with "ENOSYS".
		2116
		2117	Please refer to timerfd_create(2) for more info on this call.
		2118
		2119	The following $clockid values are available:
		2120	"IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
		2121	"IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
		2122	"IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
		2123	"IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
		2124
		2125	The following $flags values are available (Linux 2.6.27):
		2126	"IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
		2127
		2128	Example: create a new timerfd and set it to one-second repeated
		2129	alarms, then wait for two alarms:
		2130
		2131	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2132	or die "timerfd_create: $!\n";
		2133
		2134	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2135	or die "timerfd_settime: $!\n";
		2136
		2137	for (1..2) {
		2138	8 == sysread $fh, my $buf, 8
		2139	or die "timerfd read failure\n";
		2140
		2141	printf "number of expirations (likely 1): %d\n",
		2142	unpack "Q", $buf;
		2143	}
		2144
		2145	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
		2146	$new_interval, $nbw_value
		2147	This is a direct interface to the Linux timerfd_settime(2) system
		2148	call. Please refer to its manpage for more info on this call.
		2149
		2150	The new itimerspec is specified using two (possibly fractional)
		2151	second values, $new_interval and $new_value).
		2152
		2153	On success, the current interval and value are returned (as per
		2154	"timerfd_gettime"). On failure, the empty list is returned.
		2155
		2156	The following $flags values are available:
		2157	"IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
		2158
		2159	See "IO::AIO::timerfd_create" for a full example.
		2160
		2161	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2162	This is a direct interface to the Linux timerfd_gettime(2) system
		2163	call. Please refer to its manpage for more info on this call.
		2164
		2165	On success, returns the current values of interval and value for the
		2166	given timerfd (as potentially fractional second values). On failure,
		2167	the empty list is returned.
1689		2168
1690	EVENT LOOP INTEGRATION	2169	EVENT LOOP INTEGRATION
1691	It is recommended to use AnyEvent::AIO to integrate IO::AIO	2170	It is recommended to use AnyEvent::AIO to integrate IO::AIO
1692	automatically into many event loops:	2171	automatically into many event loops:
1693		2172
…		…
1743	forking, if "IO::AIO" was used in the parent. Calling it while	2222	forking, if "IO::AIO" was used in the parent. Calling it while
1744	IO::AIO is active in the process will result in undefined behaviour.	2223	IO::AIO is active in the process will result in undefined behaviour.
1745	Calling it at any time will also result in any undefined (by POSIX)	2224	Calling it at any time will also result in any undefined (by POSIX)
1746	behaviour.	2225	behaviour.
1747		2226
		2227	LINUX-SPECIFIC CALLS
		2228	When a call is documented as "linux-specific" then this means it
		2229	originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
		2230	availability and compatibility of such calls regardless of the platform
		2231	it is compiled on, so platforms such as FreeBSD which often implement
		2232	these calls will work. When in doubt, call them and see if they fail wth
		2233	"ENOSYS".
		2234
1748	MEMORY USAGE	2235	MEMORY USAGE
1749	Per-request usage:	2236	Per-request usage:
1750		2237
1751	Each aio request uses - depending on your architecture - around 100-200	2238	Each aio request uses - depending on your architecture - around 100-200
1752	bytes of memory. In addition, stat requests need a stat buffer (possibly	2239	bytes of memory. In addition, stat requests need a stat buffer (possibly
…		…
1762	In the execution phase, some aio requests require more memory for	2249	In the execution phase, some aio requests require more memory for
1763	temporary buffers, and each thread requires a stack and other data	2250	temporary buffers, and each thread requires a stack and other data
1764	structures (usually around 16k-128k, depending on the OS).	2251	structures (usually around 16k-128k, depending on the OS).
1765		2252
1766	KNOWN BUGS	2253	KNOWN BUGS
1767	Known bugs will be fixed in the next release.	2254	Known bugs will be fixed in the next release :)
		2255
		2256	KNOWN ISSUES
		2257	Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
		2258	or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
		2259	non-created hash slots or other scalars I didn't think of. It's best to
		2260	avoid such and either use scalar variables or making sure that the
		2261	scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
		2262
		2263	I am not sure anything can be done about this, so this is considered a
		2264	known issue, rather than a bug.
1768		2265
1769	SEE ALSO	2266	SEE ALSO
1770	AnyEvent::AIO for easy integration into event loops, Coro::AIO for a	2267	AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1771	more natural syntax.	2268	more natural syntax and IO::FDPass for file descriptor passing.
1772		2269
1773	AUTHOR	2270	AUTHOR
1774	Marc Lehmann <schmorp@schmorp.de>	2271	Marc Lehmann <schmorp@schmorp.de>
1775	http://home.schmorp.de/	2272	http://home.schmorp.de/
1776		2273

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Revision 1.70 by root, Sat Apr 1 02:14:05 2023 UTC