[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 1.68 by root, Mon Sep 5 00:04:07 2022 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]
229		269
230	API NOTES	270	API NOTES
231	All the "aio_*" calls are more or less thin wrappers around the syscall	271	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	272	with the same name (sans "aio_"). The arguments are similar or
233	identical, and they all accept an additional (and optional) $callback	273	identical, and they all accept an additional (and optional) $callback
…		…
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
		508	exception of "-B" and "-T").
467		509
468	The pathname passed to "aio_stat" must be absolute. See API NOTES,	510	The pathname passed to "aio_stat" must be absolute. See API NOTES,
469	above, for an explanation.	511	above, for an explanation.
470		512
471	Currently, the stats are always 64-bit-stats, i.e. instead of	513	Currently, the stats are always 64-bit-stats, i.e. instead of
…		…
479	back on traditional behaviour).	521	back on traditional behaviour).
480		522
481	"S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",	523	"S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
482	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",	524	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
483	"IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".	525	"IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
		526
		527	To access higher resolution stat timestamps, see "SUBSECOND STAT
		528	TIME ACCESS".
484		529
485	Example: Print the length of /etc/passwd:	530	Example: Print the length of /etc/passwd:
486		531
487	aio_stat "/etc/passwd", sub {	532	aio_stat "/etc/passwd", sub {
488	$_[0] and die "stat failed: $!";	533	$_[0] and die "stat failed: $!";
…		…
530	namemax => 255,	575	namemax => 255,
531	frsize => 1024,	576	frsize => 1024,
532	fsid => 1810	577	fsid => 1810
533	}	578	}
534		579
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)	580	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
618	Works like perl's "utime" function (including the special case of	581	Works like perl's "utime" function (including the special case of
619	$atime and $mtime being undef). Fractional times are supported if	582	$atime and $mtime being undef). Fractional times are supported if
620	the underlying syscalls support them.	583	the underlying syscalls support them.
621		584
622	When called with a pathname, uses utimes(2) if available, otherwise	585	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	586	available, otherwise utime(2). If called on a file descriptor, uses
624	available, otherwise returns ENOSYS, so this is not portable.	587	futimens(2) or futimes(2) if available, otherwise returns ENOSYS, so
		588	this is not portable.
625		589
626	Examples:	590	Examples:
627		591
628	# set atime and mtime to current time (basically touch(1)):	592	# set atime and mtime to current time (basically touch(1)):
629	aio_utime "path", undef, undef;	593	aio_utime "path", undef, undef;
…		…
644		608
645	aio_truncate $fh_or_path, $offset, $callback->($status)	609	aio_truncate $fh_or_path, $offset, $callback->($status)
646	Works like truncate(2) or ftruncate(2).	610	Works like truncate(2) or ftruncate(2).
647		611
648	aio_allocate $fh, $mode, $offset, $len, $callback->($status)	612	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
649	Allocates or freed disk space according to the $mode argument. See	613	Allocates or frees disk space according to the $mode argument. See
650	the linux "fallocate" docuemntation for details.	614	the linux "fallocate" documentation for details.
651		615
652	$mode can currently be 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to	616	$mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
653	allocate space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE \|	617	space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE \|
654	IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.	618	IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
655		619
		620	IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range
		621	(without leaving a hole), "FALLOC_FL_ZERO_RANGE", to zero a range,
		622	"FALLOC_FL_INSERT_RANGE" to insert a range and
		623	"FALLOC_FL_UNSHARE_RANGE" to unshare shared blocks (see your
		624	fallocate(2) manpage).
		625
656	The file system block size used by "fallocate" is presumably the	626	The file system block size used by "fallocate" is presumably the
657	"f_bsize" returned by "statvfs".	627	"f_bsize" returned by "statvfs", but different filesystems and
		628	filetypes can dictate other limitations.
658		629
659	If "fallocate" isn't available or cannot be emulated (currently no	630	If "fallocate" isn't available or cannot be emulated (currently no
660	emulation will be attempted), passes -1 and sets $! to "ENOSYS".	631	emulation will be attempted), passes -1 and sets $! to "ENOSYS".
661		632
662	aio_chmod $fh_or_path, $mode, $callback->($status)	633	aio_chmod $fh_or_path, $mode, $callback->($status)
…		…
692	the callback. If an error occurs, nothing or undef gets passed to	663	the callback. If an error occurs, nothing or undef gets passed to
693	the callback.	664	the callback.
694		665
695	aio_realpath $pathname, $callback->($path)	666	aio_realpath $pathname, $callback->($path)
696	Asynchronously make the path absolute and resolve any symlinks in	667	Asynchronously make the path absolute and resolve any symlinks in
697	$path. The resulting path only consists of directories (Same as	668	$path. The resulting path only consists of directories (same as
698	Cwd::realpath).	669	Cwd::realpath).
699		670
700	This request can be used to get the absolute path of the current	671	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).	672	working directory by passing it a path of . (a single dot).
702		673
703	aio_rename $srcpath, $dstpath, $callback->($status)	674	aio_rename $srcpath, $dstpath, $callback->($status)
704	Asynchronously rename the object at $srcpath to $dstpath, just as	675	Asynchronously rename the object at $srcpath to $dstpath, just as
705	rename(2) and call the callback with the result code.	676	rename(2) and call the callback with the result code.
		677
		678	On systems that support the AIO::WD working directory abstraction
		679	natively, the case "[$wd, "."]" as $srcpath is specialcased -
		680	instead of failing, "rename" is called on the absolute path of $wd.
		681
		682	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		683	Basically a version of "aio_rename" with an additional $flags
		684	argument. Calling this with "$flags=0" is the same as calling
		685	"aio_rename".
		686
		687	Non-zero flags are currently only supported on GNU/Linux systems
		688	that support renameat2. Other systems fail with "ENOSYS" in this
		689	case.
		690
		691	The following constants are available (missing ones are, as usual
		692	0), see renameat2(2) for details:
		693
		694	"IO::AIO::RENAME_NOREPLACE", "IO::AIO::RENAME_EXCHANGE" and
		695	"IO::AIO::RENAME_WHITEOUT".
706		696
707	aio_mkdir $pathname, $mode, $callback->($status)	697	aio_mkdir $pathname, $mode, $callback->($status)
708	Asynchronously mkdir (create) a directory and call the callback with	698	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	699	the result code. $mode will be modified by the umask at the time the
710	request is executed, so do not change your umask.	700	request is executed, so do not change your umask.
711		701
712	aio_rmdir $pathname, $callback->($status)	702	aio_rmdir $pathname, $callback->($status)
713	Asynchronously rmdir (delete) a directory and call the callback with	703	Asynchronously rmdir (delete) a directory and call the callback with
714	the result code.	704	the result code.
715		705
		706	On systems that support the AIO::WD working directory abstraction
		707	natively, the case "[$wd, "."]" is specialcased - instead of
		708	failing, "rmdir" is called on the absolute path of $wd.
		709
716	aio_readdir $pathname, $callback->($entries)	710	aio_readdir $pathname, $callback->($entries)
717	Unlike the POSIX call of the same name, "aio_readdir" reads an	711	Unlike the POSIX call of the same name, "aio_readdir" reads an
718	entire directory (i.e. opendir + readdir + closedir). The entries	712	entire directory (i.e. opendir + readdir + closedir). The entries
719	will not be sorted, and will NOT include the "." and ".." entries.	713	will not be sorted, and will NOT include the "." and ".." entries.
720		714
…		…
729	The flags are a combination of the following constants, ORed	723	The flags are a combination of the following constants, ORed
730	together (the flags will also be passed to the callback, possibly	724	together (the flags will also be passed to the callback, possibly
731	modified):	725	modified):
732		726
733	IO::AIO::READDIR_DENTS	727	IO::AIO::READDIR_DENTS
734	When this flag is off, then the callback gets an arrayref	728	Normally the callback gets an arrayref consisting of names only
735	consisting of names only (as with "aio_readdir"), otherwise it	729	(as with "aio_readdir"). If this flag is set, then the callback
736	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each	730	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
737	describing a single directory entry in more detail.	731	describing a single directory entry in more detail:
738		732
739	$name is the name of the entry.	733	$name is the name of the entry.
740		734
741	$type is one of the "IO::AIO::DT_xxx" constants:	735	$type is one of the "IO::AIO::DT_xxx" constants:
742		736
743	"IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",	737	"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",	738	"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".	739	"IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
746		740
747	"IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If	741	"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	742	you need to know, you have to run stat yourself. Also, for
749	reasons, the $type scalars are read-only: you can not modify	743	speed/memory reasons, the $type scalars are read-only: you must
750	them.	744	not modify them.
751		745
752	$inode is the inode number (which might not be exact on systems	746	$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	747	with 64 bit inode numbers and 32 bit perls). This field has
754	unspecified content on systems that do not deliver the inode	748	unspecified content on systems that do not deliver the inode
755	information.	749	information.
…		…
767	of which names with short names are tried first.	761	of which names with short names are tried first.
768		762
769	IO::AIO::READDIR_STAT_ORDER	763	IO::AIO::READDIR_STAT_ORDER
770	When this flag is set, then the names will be returned in an	764	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	765	order suitable for stat()'ing each one. That is, when you plan
772	to stat() all files in the given directory, then the returned	766	to stat() most or all files in the given directory, then the
773	order will likely be fastest.	767	returned order will likely be faster.
774		768
775	If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are	769	If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
776	specified, then the likely dirs come first, resulting in a less	770	specified, then the likely dirs come first, resulting in a less
777	optimal stat order.	771	optimal stat order for stat'ing all entries, but likely a more
		772	optimal order for finding subdirectories.
778		773
779	IO::AIO::READDIR_FOUND_UNKNOWN	774	IO::AIO::READDIR_FOUND_UNKNOWN
780	This flag should not be set when calling "aio_readdirx".	775	This flag should not be set when calling "aio_readdirx".
781	Instead, it is being set by "aio_readdirx", when any of the	776	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	777	$type's found were "IO::AIO::DT_UNKNOWN". The absence of this
783	flag therefore indicates that all $type's are known, which can	778	flag therefore indicates that all $type's are known, which can
784	be used to speed up some algorithms.	779	be used to speed up some algorithms.
785		780
		781	aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		782	Opens, reads and closes the given file. The data is put into $data,
		783	which is resized as required.
		784
		785	If $offset is negative, then it is counted from the end of the file.
		786
		787	If $length is zero, then the remaining length of the file is used.
		788	Also, in this case, the same limitations to modifying $data apply as
		789	when IO::AIO::mmap is used, i.e. it must only be modified in-place
		790	with "substr". If the size of the file is known, specifying a
		791	non-zero $length results in a performance advantage.
		792
		793	This request is similar to the older "aio_load" request, but since
		794	it is a single request, it might be more efficient to use.
		795
		796	Example: load /etc/passwd into $passwd.
		797
		798	my $passwd;
		799	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		800	$_[0] >= 0
		801	or die "/etc/passwd: $!\n";
		802
		803	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		804	print $passwd;
		805	};
		806	IO::AIO::flush;
		807
786	aio_load $pathname, $data, $callback->($status)	808	aio_load $pathname, $data, $callback->($status)
787	This is a composite request that tries to fully load the given file	809	This is a composite request that tries to fully load the given file
788	into memory. Status is the same as with aio_read.	810	into memory. Status is the same as with aio_read.
		811
		812	Using "aio_slurp" might be more efficient, as it is a single
		813	request.
789		814
790	aio_copy $srcpath, $dstpath, $callback->($status)	815	aio_copy $srcpath, $dstpath, $callback->($status)
791	Try to copy the file (directories not supported as either source	816	Try to copy the file (directories not supported as either source
792	or destination) from $srcpath to $dstpath and call the callback with	817	or destination) from $srcpath to $dstpath and call the callback with
793	a status of 0 (ok) or -1 (error, see $!).	818	a status of 0 (ok) or -1 (error, see $!).
		819
		820	Existing destination files will be truncated.
794		821
795	This is a composite request that creates the destination file with	822	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	823	mode 0200 and copies the contents of the source file into it using
797	"aio_sendfile", followed by restoring atime, mtime, access mode and	824	"aio_sendfile", followed by restoring atime, mtime, access mode and
798	uid/gid, in that order.	825	uid/gid, in that order.
…		…
815	to efficiently separate the entries of directory $path into two sets	842	to efficiently separate the entries of directory $path into two sets
816	of names, directories you can recurse into (directories), and ones	843	of names, directories you can recurse into (directories), and ones
817	you cannot recurse into (everything else, including symlinks to	844	you cannot recurse into (everything else, including symlinks to
818	directories).	845	directories).
819		846
820	"aio_scandir" is a composite request that creates of many sub	847	"aio_scandir" is a composite request that generates many sub
821	requests_ $maxreq specifies the maximum number of outstanding aio	848	requests. $maxreq specifies the maximum number of outstanding aio
822	requests that this function generates. If it is "<= 0", then a	849	requests that this function generates. If it is "<= 0", then a
823	suitable default will be chosen (currently 4).	850	suitable default will be chosen (currently 4).
824		851
825	On error, the callback is called without arguments, otherwise it	852	On error, the callback is called without arguments, otherwise it
826	receives two array-refs with path-relative entry names.	853	receives two array-refs with path-relative entry names.
…		…
873	Delete a directory tree starting (and including) $path, return the	900	Delete a directory tree starting (and including) $path, return the
874	status of the final "rmdir" only. This is a composite request that	901	status of the final "rmdir" only. This is a composite request that
875	uses "aio_scandir" to recurse into and rmdir directories, and unlink	902	uses "aio_scandir" to recurse into and rmdir directories, and unlink
876	everything else.	903	everything else.
877		904
		905	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		906	aio_ioctl $fh, $request, $buf, $callback->($status)
		907	These work just like the "fcntl" and "ioctl" built-in functions,
		908	except they execute asynchronously and pass the return value to the
		909	callback.
		910
		911	Both calls can be used for a lot of things, some of which make more
		912	sense to run asynchronously in their own thread, while some others
		913	make less sense. For example, calls that block waiting for external
		914	events, such as locking, will also lock down an I/O thread while it
		915	is waiting, which can deadlock the whole I/O system. At the same
		916	time, there might be no alternative to using a thread to wait.
		917
		918	So in general, you should only use these calls for things that do
		919	(filesystem) I/O, not for things that wait for other events
		920	(network, other processes), although if you are careful and know
		921	what you are doing, you still can.
		922
		923	The following constants are available and can be used for normal
		924	"ioctl" and "fcntl" as well (missing ones are, as usual 0):
		925
		926	"F_DUPFD_CLOEXEC",
		927
		928	"F_OFD_GETLK", "F_OFD_SETLK", "F_OFD_GETLKW",
		929
		930	"FIFREEZE", "FITHAW", "FITRIM", "FICLONE", "FICLONERANGE",
		931	"FIDEDUPERANGE".
		932
		933	"F_ADD_SEALS", "F_GET_SEALS", "F_SEAL_SEAL", "F_SEAL_SHRINK",
		934	"F_SEAL_GROW" and "F_SEAL_WRITE".
		935
		936	"FS_IOC_GETFLAGS", "FS_IOC_SETFLAGS", "FS_IOC_GETVERSION",
		937	"FS_IOC_SETVERSION", "FS_IOC_FIEMAP".
		938
		939	"FS_IOC_FSGETXATTR", "FS_IOC_FSSETXATTR",
		940	"FS_IOC_SET_ENCRYPTION_POLICY", "FS_IOC_GET_ENCRYPTION_PWSALT",
		941	"FS_IOC_GET_ENCRYPTION_POLICY", "FS_KEY_DESCRIPTOR_SIZE".
		942
		943	"FS_SECRM_FL", "FS_UNRM_FL", "FS_COMPR_FL", "FS_SYNC_FL",
		944	"FS_IMMUTABLE_FL", "FS_APPEND_FL", "FS_NODUMP_FL", "FS_NOATIME_FL",
		945	"FS_DIRTY_FL", "FS_COMPRBLK_FL", "FS_NOCOMP_FL", "FS_ENCRYPT_FL",
		946	"FS_BTREE_FL", "FS_INDEX_FL", "FS_JOURNAL_DATA_FL", "FS_NOTAIL_FL",
		947	"FS_DIRSYNC_FL", "FS_TOPDIR_FL", "FS_FL_USER_MODIFIABLE".
		948
		949	"FS_XFLAG_REALTIME", "FS_XFLAG_PREALLOC", "FS_XFLAG_IMMUTABLE",
		950	"FS_XFLAG_APPEND", "FS_XFLAG_SYNC", "FS_XFLAG_NOATIME",
		951	"FS_XFLAG_NODUMP", "FS_XFLAG_RTINHERIT", "FS_XFLAG_PROJINHERIT",
		952	"FS_XFLAG_NOSYMLINKS", "FS_XFLAG_EXTSIZE", "FS_XFLAG_EXTSZINHERIT",
		953	"FS_XFLAG_NODEFRAG", "FS_XFLAG_FILESTREAM", "FS_XFLAG_DAX",
		954	"FS_XFLAG_HASATTR",
		955
878	aio_sync $callback->($status)	956	aio_sync $callback->($status)
879	Asynchronously call sync and call the callback when finished.	957	Asynchronously call sync and call the callback when finished.
880		958
881	aio_fsync $fh, $callback->($status)	959	aio_fsync $fh, $callback->($status)
882	Asynchronously call fsync on the given filehandle and call the	960	Asynchronously call fsync on the given filehandle and call the
…		…
918	Future versions of this function might fall back to other methods	996	Future versions of this function might fall back to other methods
919	when "fsync" on the directory fails (such as calling "sync").	997	when "fsync" on the directory fails (such as calling "sync").
920		998
921	Passes 0 when everything went ok, and -1 on error.	999	Passes 0 when everything went ok, and -1 on error.
922		1000
923	aio_msync $scalar, $offset = 0, $length = undef, flags = 0,	1001	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
924	$callback->($status)	1002	$callback->($status)
925	This is a rather advanced IO::AIO call, which only works on	1003	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	1004	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,	1005	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	1006	note that the scalar must only be modified in-place while an aio
…		…
930		1008
931	It calls the "msync" function of your OS, if available, with the	1009	It calls the "msync" function of your OS, if available, with the
932	memory area starting at $offset in the string and ending $length	1010	memory area starting at $offset in the string and ending $length
933	bytes later. If $length is negative, counts from the end, and if	1011	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	1012	$length is "undef", then it goes till the end of the string. The
935	flags can be a combination of "IO::AIO::MS_ASYNC",	1013	flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus
936	"IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".	1014	an optional "IO::AIO::MS_INVALIDATE".
937		1015
938	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,	1016	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
939	$callback->($status)	1017	$callback->($status)
940	This is a rather advanced IO::AIO call, which works best on	1018	This is a rather advanced IO::AIO call, which works best on
941	mmap(2)ed scalars.	1019	mmap(2)ed scalars.
942		1020
943	It touches (reads or writes) all memory pages in the specified range	1021	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	1022	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	1023	"aio_msync", above, except for flags, which must be either 0 (which
946	reads all pages and ensures they are instantiated) or	1024	reads all pages and ensures they are instantiated) or
947	"IO::AIO::MT_MODIFY", which modifies the memory page s(by reading	1025	"IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
948	and writing an octet from it, which dirties the page).	1026	and writing an octet from it, which dirties the page).
949		1027
950	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1028	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
951	This is a rather advanced IO::AIO call, which works best on	1029	This is a rather advanced IO::AIO call, which works best on
952	mmap(2)ed scalars.	1030	mmap(2)ed scalars.
…		…
972	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;	1050	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
973	aio_mlock $data; # mlock in background	1051	aio_mlock $data; # mlock in background
974		1052
975	aio_mlockall $flags, $callback->($status)	1053	aio_mlockall $flags, $callback->($status)
976	Calls the "mlockall" function with the given $flags (a combination	1054	Calls the "mlockall" function with the given $flags (a combination
977	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").	1055	of "IO::AIO::MCL_CURRENT", "IO::AIO::MCL_FUTURE" and
		1056	"IO::AIO::MCL_ONFAULT").
978		1057
979	On systems that do not implement "mlockall", this function returns	1058	On systems that do not implement "mlockall", this function returns
980	-1 and sets errno to "ENOSYS".	1059	-1 and sets errno to "ENOSYS". Similarly, flag combinations not
		1060	supported by the system result in a return value of -1 with errno
		1061	being set to "EINVAL".
981		1062
982	Note that the corresponding "munlockall" is synchronous and is	1063	Note that the corresponding "munlockall" is synchronous and is
983	documented under "MISCELLANEOUS FUNCTIONS".	1064	documented under "MISCELLANEOUS FUNCTIONS".
984		1065
985	Example: asynchronously lock all current and future pages into	1066	Example: asynchronously lock all current and future pages into
…		…
1027	"IO::AIO::FIEMAP_EXTENT_DATA_INLINE",	1108	"IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1028	"IO::AIO::FIEMAP_EXTENT_DATA_TAIL",	1109	"IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1029	"IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"	1110	"IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1030	or "IO::AIO::FIEMAP_EXTENT_SHARED".	1111	or "IO::AIO::FIEMAP_EXTENT_SHARED".
1031		1112
1032	At the time of this writing (Linux 3.2), this requets is unreliable	1113	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	1114	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	1115	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	1116	large number of extents. The code (only) works around all these
1036	is undef.	1117	issues if $count is "undef".
1037		1118
1038	aio_group $callback->(...)	1119	aio_group $callback->(...)
1039	This is a very special aio request: Instead of doing something, it	1120	This is a very special aio request: Instead of doing something, it
1040	is a container for other aio requests, which is useful if you want	1121	is a container for other aio requests, which is useful if you want
1041	to bundle many requests into a single, composite, request with a	1122	to bundle many requests into a single, composite, request with a
…		…
1121	aio_stat [$etcdir, "passwd"], sub {	1202	aio_stat [$etcdir, "passwd"], sub {
1122	# yay	1203	# yay
1123	};	1204	};
1124	};	1205	};
1125		1206
1126	That "aio_wd" is a request and not a normal function shows that creating	1207	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	1208	creating an IO::AIO::WD object is itself a potentially blocking
1128	is why it is done asynchronously.	1209	operation, which is why it is done asynchronously.
1129		1210
1130	To stat the directory obtained with "aio_wd" above, one could write	1211	To stat the directory obtained with "aio_wd" above, one could write
1131	either of the following three request calls:	1212	either of the following three request calls:
1132		1213
1133	aio_lstat "/etc" , sub { ... # pathname as normal string	1214	aio_lstat "/etc" , sub { ... # pathname as normal string
…		…
1150	There are some caveats: when directories get renamed (or deleted), the	1231	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	1232	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,	1233	nowhere at all), while the directory fd, if available on the system,
1153	will still point to the original directory. Most functions accepting a	1234	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	1235	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	1236	older systems. Some functions (such as "aio_realpath") will always rely
1156	string form of the pathname.	1237	on the string form of the pathname.
1157		1238
1158	So this fucntionality is mainly useful to get some protection against	1239	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	1240	"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	1241	future reference, and to speed up doing many operations in the same
1161	directory (e.g. when stat'ing all files in a directory).	1242	directory (e.g. when stat'ing all files in a directory).
1162		1243
1163	The following functions implement this working directory abstraction:	1244	The following functions implement this working directory abstraction:
…		…
1173	Since passing "undef" as working directory component of a pathname	1254	Since passing "undef" as working directory component of a pathname
1174	fails the request with "ENOENT", there is often no need for error	1255	fails the request with "ENOENT", there is often no need for error
1175	checking in the "aio_wd" callback, as future requests using the	1256	checking in the "aio_wd" callback, as future requests using the
1176	value will fail in the expected way.	1257	value will fail in the expected way.
1177		1258
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	1259	IO::AIO::CWD
1182	This is a compiletime constant (object) that represents the process	1260	This is a compile time constant (object) that represents the process
1183	current working directory.	1261	current working directory.
1184		1262
1185	Specifying this object as working directory object for a pathname is	1263	Specifying this object as working directory object for a pathname is
1186	as if the pathname would be specified directly, without a directory	1264	as if the pathname would be specified directly, without a directory
1187	object, e.g., these calls are functionally identical:	1265	object. For example, these calls are functionally identical:
1188		1266
1189	aio_stat "somefile", sub { ... };	1267	aio_stat "somefile", sub { ... };
1190	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };	1268	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1269
		1270	To recover the path associated with an IO::AIO::WD object, you can use
		1271	"aio_realpath":
		1272
		1273	aio_realpath $wd, sub {
		1274	warn "path is $_[0]\n";
		1275	};
		1276
		1277	Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir"
		1278	sometimes, fall back to using an absolue path.
1191		1279
1192	IO::AIO::REQ CLASS	1280	IO::AIO::REQ CLASS
1193	All non-aggregate "aio_*" functions return an object of this class when	1281	All non-aggregate "aio_*" functions return an object of this class when
1194	called in non-void context.	1282	called in non-void context.
1195		1283
…		…
1347	results.	1435	results.
1348		1436
1349	See "poll_cb" for an example.	1437	See "poll_cb" for an example.
1350		1438
1351	IO::AIO::poll_cb	1439	IO::AIO::poll_cb
1352	Process some outstanding events on the result pipe. You have to call	1440	Process some requests that have reached the result phase (i.e. they
		1441	have been executed but the results are not yet reported). You have
		1442	to call this "regularly" to finish outstanding requests.
		1443
1353	this regularly. Returns 0 if all events could be processed (or there	1444	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	1445	to process), or -1 if it returned earlier for whatever reason.
1355	whatever reason. Returns immediately when no events are outstanding.	1446	Returns immediately when no events are outstanding. The amount of
1356	The amount of events processed depends on the settings of	1447	events processed depends on the settings of "IO::AIO::max_poll_req",
1357	"IO::AIO::max_poll_req" and "IO::AIO::max_poll_time".	1448	"IO::AIO::max_poll_time" and "IO::AIO::max_outstanding".
1358		1449
1359	If not all requests were processed for whatever reason, the	1450	If not all requests were processed for whatever reason, the poll
1360	filehandle will still be ready when "poll_cb" returns, so normally	1451	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.	1452	normally you don't have to do anything special to have it called
		1453	later.
1362		1454
1363	Apart from calling "IO::AIO::poll_cb" when the event filehandle	1455	Apart from calling "IO::AIO::poll_cb" when the event filehandle
1364	becomes ready, it can be beneficial to call this function from loops	1456	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	1457	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	1458	processed when they become available and not just when the loop is
…		…
1374	Event->io (fd => IO::AIO::poll_fileno,	1466	Event->io (fd => IO::AIO::poll_fileno,
1375	poll => 'r', async => 1,	1467	poll => 'r', async => 1,
1376	cb => \&IO::AIO::poll_cb);	1468	cb => \&IO::AIO::poll_cb);
1377		1469
1378	IO::AIO::poll_wait	1470	IO::AIO::poll_wait
1379	If there are any outstanding requests and none of them in the result	1471	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	1472	requests are outstanding anymore.
1381	(simply does a "select" on the filehandle. This is useful if you	1473
1382	want to synchronously wait for some requests to finish).	1474	This is useful if you want to synchronously wait for some requests
		1475	to become ready, without actually handling them.
1383		1476
1384	See "nreqs" for an example.	1477	See "nreqs" for an example.
1385		1478
1386	IO::AIO::poll	1479	IO::AIO::poll
1387	Waits until some requests have been handled.	1480	Waits until some requests have been handled.
…		…
1396		1489
1397	Strictly equivalent to:	1490	Strictly equivalent to:
1398		1491
1399	IO::AIO::poll_wait, IO::AIO::poll_cb	1492	IO::AIO::poll_wait, IO::AIO::poll_cb
1400	while IO::AIO::nreqs;	1493	while IO::AIO::nreqs;
		1494
		1495	This function can be useful at program aborts, to make sure
		1496	outstanding I/O has been done ("IO::AIO" uses an "END" block which
		1497	already calls this function on normal exits), or when you are merely
		1498	using "IO::AIO" for its more advanced functions, rather than for
		1499	async I/O, e.g.:
		1500
		1501	my ($dirs, $nondirs);
		1502	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1503	IO::AIO::flush;
		1504	# $dirs, $nondirs are now set
1401		1505
1402	IO::AIO::max_poll_reqs $nreqs	1506	IO::AIO::max_poll_reqs $nreqs
1403	IO::AIO::max_poll_time $seconds	1507	IO::AIO::max_poll_time $seconds
1404	These set the maximum number of requests (default 0, meaning	1508	These set the maximum number of requests (default 0, meaning
1405	infinity) that are being processed by "IO::AIO::poll_cb" in one	1509	infinity) that are being processed by "IO::AIO::poll_cb" in one
…		…
1495	no longer exceeded.	1599	no longer exceeded.
1496		1600
1497	In other words, this setting does not enforce a queue limit, but can	1601	In other words, this setting does not enforce a queue limit, but can
1498	be used to make poll functions block if the limit is exceeded.	1602	be used to make poll functions block if the limit is exceeded.
1499		1603
1500	This is a very bad function to use in interactive programs because	1604	This is a bad function to use in interactive programs because it
1501	it blocks, and a bad way to reduce concurrency because it is	1605	blocks, and a bad way to reduce concurrency because it is inexact.
1502	inexact: Better use an "aio_group" together with a feed callback.	1606	If you need to issue many requests without being able to call a poll
		1607	function on demand, it is better to use an "aio_group" together with
		1608	a feed callback.
1503		1609
1504	It's main use is in scripts without an event loop - when you want to	1610	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:	1611	stat a lot of files, you can write something like this:
1506		1612
1507	IO::AIO::max_outstanding 32;	1613	IO::AIO::max_outstanding 32;
1508		1614
1509	for my $path (...) {	1615	for my $path (...) {
1510	aio_stat $path , ...;	1616	aio_stat $path , ...;
…		…
1512	}	1618	}
1513		1619
1514	IO::AIO::flush;	1620	IO::AIO::flush;
1515		1621
1516	The call to "poll_cb" inside the loop will normally return	1622	The call to "poll_cb" inside the loop will normally return
1517	instantly, but as soon as more thna 32 reqeusts are in-flight, it	1623	instantly, allowing the loop to progress, but as soon as more than
1518	will block until some requests have been handled. This keeps the	1624	32 requests are in-flight, it will block until some requests have
1519	loop from pushing a large number of "aio_stat" requests onto the	1625	been handled. This keeps the loop from pushing a large number of
1520	queue.	1626	"aio_stat" requests onto the queue (which, with many paths to stat,
		1627	can use up a lot of memory).
1521		1628
1522	The default value for "max_outstanding" is very large, so there is	1629	The default value for "max_outstanding" is very large, so there is
1523	no practical limit on the number of outstanding requests.	1630	no practical limit on the number of outstanding requests.
1524		1631
1525	STATISTICAL INFORMATION	1632	STATISTICAL INFORMATION
…		…
1539		1646
1540	IO::AIO::npending	1647	IO::AIO::npending
1541	Returns the number of requests currently in the pending state	1648	Returns the number of requests currently in the pending state
1542	(executed, but not yet processed by poll_cb).	1649	(executed, but not yet processed by poll_cb).
1543		1650
		1651	SUBSECOND STAT TIME ACCESS
		1652	Both "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" functions can
		1653	generally find access/modification and change times with subsecond time
		1654	accuracy of the system supports it, but perl's built-in functions only
		1655	return the integer part.
		1656
		1657	The following functions return the timestamps of the most recent stat
		1658	with subsecond precision on most systems and work both after
		1659	"aio_stat"/"aio_lstat" and perl's "stat"/"lstat" calls. Their return
		1660	value is only meaningful after a successful "stat"/"lstat" call, or
		1661	during/after a successful "aio_stat"/"aio_lstat" callback.
		1662
		1663	This is similar to the Time::HiRes "stat" functions, but can return full
		1664	resolution without rounding and work with standard perl "stat",
		1665	alleviating the need to call the special "Time::HiRes" functions, which
		1666	do not act like their perl counterparts.
		1667
		1668	On operating systems or file systems where subsecond time resolution is
		1669	not supported or could not be detected, a fractional part of 0 is
		1670	returned, so it is always safe to call these functions.
		1671
		1672	$seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime,
		1673	IO::AIO::st_btime
		1674	Return the access, modication, change or birth time, respectively,
		1675	including fractional part. Due to the limited precision of floating
		1676	point, the accuracy on most platforms is only a bit better than
		1677	milliseconds for times around now - see the nsec function family,
		1678	below, for full accuracy.
		1679
		1680	File birth time is only available when the OS and perl support it
		1681	(on FreeBSD and NetBSD at the time of this writing, although support
		1682	is adaptive, so if your OS/perl gains support, IO::AIO can take
		1683	advantage of it). On systems where it isn't available, 0 is
		1684	currently returned, but this might change to "undef" in a future
		1685	version.
		1686
		1687	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		1688	Returns access, modification, change and birth time all in one go,
		1689	and maybe more times in the future version.
		1690
		1691	$nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec,
		1692	IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		1693	Return the fractional access, modifcation, change or birth time, in
		1694	nanoseconds, as an integer in the range 0 to 999999999.
		1695
		1696	Note that no accessors are provided for access, modification and
		1697	change times - you need to get those from "stat _" if required ("int
		1698	IO::AIO::st_atime" and so on will not generally give you the
		1699	correct value).
		1700
		1701	$seconds = IO::AIO::st_btimesec
		1702	The (integral) seconds part of the file birth time, if available.
		1703
		1704	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		1705	Like the functions above, but returns all four times in one go (and
		1706	maybe more in future versions).
		1707
		1708	$counter = IO::AIO::st_gen
		1709	Returns the generation counter (in practice this is just a random
		1710	number) of the file. This is only available on platforms which have
		1711	this member in their "struct stat" (most BSDs at the time of this
		1712	writing) and generally only to the root usert. If unsupported, 0 is
		1713	returned, but this might change to "undef" in a future version.
		1714
		1715	Example: print the high resolution modification time of /etc, using
		1716	"stat", and "IO::AIO::aio_stat".
		1717
		1718	if (stat "/etc") {
		1719	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		1720	}
		1721
		1722	IO::AIO::aio_stat "/etc", sub {
		1723	$_[0]
		1724	and return;
		1725
		1726	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		1727	};
		1728
		1729	IO::AIO::flush;
		1730
		1731	Output of the awbove on my system, showing reduced and full accuracy:
		1732
		1733	stat(/etc) mtime: 1534043702.020808
		1734	aio_stat(/etc) mtime: 1534043702.020807792
		1735
1544	MISCELLANEOUS FUNCTIONS	1736	MISCELLANEOUS FUNCTIONS
1545	IO::AIO implements some functions that might be useful, but are not	1737	IO::AIO implements some functions that are useful when you want to use
1546	asynchronous.	1738	some "Advanced I/O" function not available to in Perl, without going the
		1739	"Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
		1740	counterpart.
		1741
		1742	$retval = IO::AIO::fexecve $fh, $argv, $envp
		1743	A more-or-less direct equivalent to the POSIX "fexecve" functions,
		1744	which allows you to specify the program to be executed via a file
		1745	descriptor (or handle). Returns -1 and sets errno to "ENOSYS" if not
		1746	available.
		1747
		1748	$numfd = IO::AIO::get_fdlimit
		1749	Tries to find the current file descriptor limit and returns it, or
		1750	"undef" and sets $! in case of an error. The limit is one larger
		1751	than the highest valid file descriptor number.
		1752
		1753	IO::AIO::min_fdlimit [$numfd]
		1754	Try to increase the current file descriptor limit(s) to at least
		1755	$numfd by changing the soft or hard file descriptor resource limit.
		1756	If $numfd is missing, it will try to set a very high limit, although
		1757	this is not recommended when you know the actual minimum that you
		1758	require.
		1759
		1760	If the limit cannot be raised enough, the function makes a
		1761	best-effort attempt to increase the limit as much as possible, using
		1762	various tricks, while still failing. You can query the resulting
		1763	limit using "IO::AIO::get_fdlimit".
		1764
		1765	If an error occurs, returns "undef" and sets $!, otherwise returns
		1766	true.
1547		1767
1548	IO::AIO::sendfile $ofh, $ifh, $offset, $count	1768	IO::AIO::sendfile $ofh, $ifh, $offset, $count
1549	Calls the "eio_sendfile_sync" function, which is like	1769	Calls the "eio_sendfile_sync" function, which is like
1550	"aio_sendfile", but is blocking (this makes most sense if you know	1770	"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	1771	the input data is likely cached already and the output filehandle is
…		…
1568	details). The following advice constants are available:	1788	details). The following advice constants are available:
1569	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",	1789	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1570	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",	1790	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1571	"IO::AIO::MADV_DONTNEED".	1791	"IO::AIO::MADV_DONTNEED".
1572		1792
		1793	If $offset is negative, counts from the end. If $length is negative,
		1794	the remaining length of the $scalar is used. If possible, $length
		1795	will be reduced to fit into the $scalar.
		1796
1573	On systems that do not implement "posix_madvise", this function	1797	On systems that do not implement "posix_madvise", this function
1574	returns ENOSYS, otherwise the return value of "posix_madvise".	1798	returns ENOSYS, otherwise the return value of "posix_madvise".
1575		1799
1576	IO::AIO::mprotect $scalar, $offset, $len, $protect	1800	IO::AIO::mprotect $scalar, $offset, $len, $protect
1577	Simply calls the "mprotect" function on the preferably AIO::mmap'ed	1801	Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1578	$scalar (see its manpage for details). The following protect	1802	$scalar (see its manpage for details). The following protect
1579	constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",	1803	constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1580	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".	1804	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1581		1805
		1806	If $offset is negative, counts from the end. If $length is negative,
		1807	the remaining length of the $scalar is used. If possible, $length
		1808	will be reduced to fit into the $scalar.
		1809
1582	On systems that do not implement "mprotect", this function returns	1810	On systems that do not implement "mprotect", this function returns
1583	ENOSYS, otherwise the return value of "mprotect".	1811	ENOSYS, otherwise the return value of "mprotect".
1584		1812
1585	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	1813	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1586	Memory-maps a file (or anonymous memory range) and attaches it to	1814	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	1815	the given $scalar, which will act like a string scalar. Returns true
1588	on success, and false otherwise.	1816	on success, and false otherwise.
1589		1817
		1818	The scalar must exist, but its contents do not matter - this means
		1819	you cannot use a nonexistant array or hash element. When in doubt,
		1820	"undef" the scalar first.
		1821
1590	The only operations allowed on the scalar are "substr"/"vec" that	1822	The only operations allowed on the mmapped scalar are
1591	don't change the string length, and most read-only operations such	1823	"substr"/"vec", which don't change the string length, and most
1592	as copying it or searching it with regexes and so on.	1824	read-only operations such as copying it or searching it with regexes
		1825	and so on.
1593		1826
1594	Anything else is unsafe and will, at best, result in memory leaks.	1827	Anything else is unsafe and will, at best, result in memory leaks.
1595		1828
1596	The memory map associated with the $scalar is automatically removed	1829	The memory map associated with the $scalar is automatically removed
1597	when the $scalar is destroyed, or when the "IO::AIO::mmap" or	1830	when the $scalar is undef'd or destroyed, or when the
1598	"IO::AIO::munmap" functions are called.	1831	"IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1599		1832
1600	This calls the "mmap"(2) function internally. See your system's	1833	This calls the "mmap"(2) function internally. See your system's
1601	manual page for details on the $length, $prot and $flags parameters.	1834	manual page for details on the $length, $prot and $flags parameters.
1602		1835
1603	The $length must be larger than zero and smaller than the actual	1836	The $length must be larger than zero and smaller than the actual
…		…
1607	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or	1840	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1608	"IO::AIO::PROT_WRITE",	1841	"IO::AIO::PROT_WRITE",
1609		1842
1610	$flags can be a combination of "IO::AIO::MAP_SHARED" or	1843	$flags can be a combination of "IO::AIO::MAP_SHARED" or
1611	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when	1844	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1612	not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"	1845	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	1846	"MAP_ANON" if your system only provides this constant),
		1847	"IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1614	constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",	1848	"IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1615	"IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or	1849	"IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1616	"IO::AIO::MAP_NONBLOCK"	1850	"IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_STACK",
		1851	"IO::AIO::MAP_FIXED_NOREPLACE", "IO::AIO::MAP_SHARED_VALIDATE",
		1852	"IO::AIO::MAP_SYNC" or "IO::AIO::MAP_UNINITIALIZED".
1617		1853
1618	If $fh is "undef", then a file descriptor of -1 is passed.	1854	If $fh is "undef", then a file descriptor of -1 is passed.
1619		1855
1620	$offset is the offset from the start of the file - it generally must	1856	$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.	1857	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
…		…
1633		1869
1634	my $fast_md5 = md5 $data;	1870	my $fast_md5 = md5 $data;
1635		1871
1636	IO::AIO::munmap $scalar	1872	IO::AIO::munmap $scalar
1637	Removes a previous mmap and undefines the $scalar.	1873	Removes a previous mmap and undefines the $scalar.
		1874
		1875	IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[,
		1876	$new_address = 0]
		1877	Calls the Linux-specific mremap(2) system call. The $scalar must
		1878	have been mapped by "IO::AIO::mmap", and $flags must currently
		1879	either be 0 or "IO::AIO::MREMAP_MAYMOVE".
		1880
		1881	Returns true if successful, and false otherwise. If the underlying
		1882	mmapped region has changed address, then the true value has the
		1883	numerical value 1, otherwise it has the numerical value 0:
		1884
		1885	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		1886	or die "mremap: $!";
		1887
		1888	if ($success*1) {
		1889	warn "scalar has chanegd address in memory\n";
		1890	}
		1891
		1892	"IO::AIO::MREMAP_FIXED" and the $new_address argument are currently
		1893	implemented, but not supported and might go away in a future
		1894	version.
		1895
		1896	On systems where this call is not supported or is not emulated, this
		1897	call returns falls and sets $! to "ENOSYS".
		1898
		1899	IO::AIO::mlockall $flags
		1900	Calls the "eio_mlockall_sync" function, which is like
		1901	"aio_mlockall", but is blocking.
1638		1902
1639	IO::AIO::munlock $scalar, $offset = 0, $length = undef	1903	IO::AIO::munlock $scalar, $offset = 0, $length = undef
1640	Calls the "munlock" function, undoing the effects of a previous	1904	Calls the "munlock" function, undoing the effects of a previous
1641	"aio_mlock" call (see its description for details).	1905	"aio_mlock" call (see its description for details).
1642		1906
1643	IO::AIO::munlockall	1907	IO::AIO::munlockall
1644	Calls the "munlockall" function.	1908	Calls the "munlockall" function.
1645		1909
1646	On systems that do not implement "munlockall", this function returns	1910	On systems that do not implement "munlockall", this function returns
1647	ENOSYS, otherwise the return value of "munlockall".	1911	ENOSYS, otherwise the return value of "munlockall".
		1912
		1913	$fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		1914	Uses the GNU/Linux accept4(2) syscall, if available, to accept a
		1915	socket and return the new file handle on success, or sets $! and
		1916	returns "undef" on error.
		1917
		1918	The remote name of the new socket will be stored in $sockaddr, which
		1919	will be extended to allow for at least $sockaddr_maxlen octets. If
		1920	the socket name does not fit into $sockaddr_maxlen octets, this is
		1921	signaled by returning a longer string in $sockaddr, which might or
		1922	might not be truncated.
		1923
		1924	To accept name-less sockets, use "undef" for $sockaddr and 0 for
		1925	$sockaddr_maxlen.
		1926
		1927	The main reasons to use this syscall rather than portable accept(2)
		1928	are that you can specify "SOCK_NONBLOCK" and/or "SOCK_CLOEXEC" flags
		1929	and you can accept name-less sockets by specifying 0 for
		1930	$sockaddr_maxlen, which is sadly not possible with perl's interface
		1931	to "accept".
1648		1932
1649	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags	1933	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	1934	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	1935	$w_off are "undef", then "NULL" is passed for these, otherwise they
1652	should be the file offset.	1936	should be the file offset.
…		…
1659	"IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".	1943	"IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1660		1944
1661	See the splice(2) manpage for details.	1945	See the splice(2) manpage for details.
1662		1946
1663	IO::AIO::tee $r_fh, $w_fh, $length, $flags	1947	IO::AIO::tee $r_fh, $w_fh, $length, $flags
1664	Calls the GNU/Linux tee(2) syscall, see it's manpage and the	1948	Calls the GNU/Linux tee(2) syscall, see its manpage and the
1665	description for "IO::AIO::splice" above for details.	1949	description for "IO::AIO::splice" above for details.
		1950
		1951	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		1952	Attempts to query or change the pipe buffer size. Obviously works
		1953	only on pipes, and currently works only on GNU/Linux systems, and
		1954	fails with -1/"ENOSYS" everywhere else. If anybody knows how to
		1955	influence pipe buffer size on other systems, drop me a note.
		1956
		1957	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		1958	This is a direct interface to the Linux pipe2(2) system call. If
		1959	$flags is missing or 0, then this should be the same as a call to
		1960	perl's built-in "pipe" function and create a new pipe, and works on
		1961	systems that lack the pipe2 syscall. On win32, this case invokes
		1962	"_pipe (..., 4096, O_BINARY)".
		1963
		1964	If $flags is non-zero, it tries to invoke the pipe2 system call with
		1965	the given flags (Linux 2.6.27, glibc 2.9).
		1966
		1967	On success, the read and write file handles are returned.
		1968
		1969	On error, nothing will be returned. If the pipe2 syscall is missing
		1970	and $flags is non-zero, fails with "ENOSYS".
		1971
		1972	Please refer to pipe2(2) for more info on the $flags, but at the
		1973	time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
		1974	and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
		1975	supported.
		1976
		1977	Example: create a pipe race-free w.r.t. threads and fork:
		1978
		1979	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		1980	or die "pipe2: $!\n";
		1981
		1982	$fh = IO::AIO::memfd_create $pathname[, $flags]
		1983	This is a direct interface to the Linux memfd_create(2) system call.
		1984	The (unhelpful) default for $flags is 0, but your default should be
		1985	"IO::AIO::MFD_CLOEXEC".
		1986
		1987	On success, the new memfd filehandle is returned, otherwise returns
		1988	"undef". If the memfd_create syscall is missing, fails with
		1989	"ENOSYS".
		1990
		1991	Please refer to memfd_create(2) for more info on this call.
		1992
		1993	The following $flags values are available: "IO::AIO::MFD_CLOEXEC",
		1994	"IO::AIO::MFD_ALLOW_SEALING", "IO::AIO::MFD_HUGETLB",
		1995	"IO::AIO::MFD_HUGETLB_2MB" and "IO::AIO::MFD_HUGETLB_1GB".
		1996
		1997	Example: create a new memfd.
		1998
		1999	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2000	or die "memfd_create: $!\n";
		2001
		2002	$fh = IO::AIO::pidfd_open $pid[, $flags]
		2003	This is an interface to the Linux pidfd_open(2) system call. The
		2004	default for $flags is 0.
		2005
		2006	On success, a new pidfd filehandle is returned (that is already set
		2007	to close-on-exec), otherwise returns "undef". If the syscall is
		2008	missing, fails with "ENOSYS".
		2009
		2010	Example: open pid 6341 as pidfd.
		2011
		2012	my $fh = IO::AIO::pidfd_open 6341
		2013	or die "pidfd_open: $!\n";
		2014
		2015	$status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[,
		2016	$flags]]
		2017	This is an interface to the Linux pidfd_send_signal system call. The
		2018	default for $siginfo is "undef" and the default for $flags is 0.
		2019
		2020	Returns the system call status. If the syscall is missing, fails
		2021	with "ENOSYS".
		2022
		2023	When specified, $siginfo must be a reference to a hash with one or
		2024	more of the following members:
		2025
		2026	code - the "si_code" member
		2027	pid - the "si_pid" member
		2028	uid - the "si_uid" member
		2029	value_int - the "si_value.sival_int" member
		2030	value_ptr - the "si_value.sival_ptr" member, specified as an integer
		2031
		2032	Example: send a SIGKILL to the specified process.
		2033
		2034	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
		2035	and die "pidfd_send_signal: $!\n";
		2036
		2037	Example: send a SIGKILL to the specified process with extra data.
		2038
		2039	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
		2040	and die "pidfd_send_signal: $!\n";
		2041
		2042	$fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		2043	This is an interface to the Linux pidfd_getfd system call. The
		2044	default for $flags is 0.
		2045
		2046	On success, returns a dup'ed copy of the target file descriptor
		2047	(specified as an integer) returned (that is already set to
		2048	close-on-exec), otherwise returns "undef". If the syscall is
		2049	missing, fails with "ENOSYS".
		2050
		2051	Example: get a copy of standard error of another process and print
		2052	soemthing to it.
		2053
		2054	my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
		2055	or die "pidfd_getfd: $!\n";
		2056	print $errfh "stderr\n";
		2057
		2058	$fh = IO::AIO::eventfd [$initval, [$flags]]
		2059	This is a direct interface to the Linux eventfd(2) system call. The
		2060	(unhelpful) defaults for $initval and $flags are 0 for both.
		2061
		2062	On success, the new eventfd filehandle is returned, otherwise
		2063	returns "undef". If the eventfd syscall is missing, fails with
		2064	"ENOSYS".
		2065
		2066	Please refer to eventfd(2) for more info on this call.
		2067
		2068	The following symbol flag values are available:
		2069	"IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
		2070	"IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
		2071
		2072	Example: create a new eventfd filehandle:
		2073
		2074	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2075	or die "eventfd: $!\n";
		2076
		2077	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		2078	This is a direct interface to the Linux timerfd_create(2) system
		2079	call. The (unhelpful) default for $flags is 0, but your default
		2080	should be "IO::AIO::TFD_CLOEXEC".
		2081
		2082	On success, the new timerfd filehandle is returned, otherwise
		2083	returns "undef". If the timerfd_create syscall is missing, fails
		2084	with "ENOSYS".
		2085
		2086	Please refer to timerfd_create(2) for more info on this call.
		2087
		2088	The following $clockid values are available:
		2089	"IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
		2090	"IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
		2091	"IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
		2092	"IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
		2093
		2094	The following $flags values are available (Linux 2.6.27):
		2095	"IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
		2096
		2097	Example: create a new timerfd and set it to one-second repeated
		2098	alarms, then wait for two alarms:
		2099
		2100	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2101	or die "timerfd_create: $!\n";
		2102
		2103	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2104	or die "timerfd_settime: $!\n";
		2105
		2106	for (1..2) {
		2107	8 == sysread $fh, my $buf, 8
		2108	or die "timerfd read failure\n";
		2109
		2110	printf "number of expirations (likely 1): %d\n",
		2111	unpack "Q", $buf;
		2112	}
		2113
		2114	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
		2115	$new_interval, $nbw_value
		2116	This is a direct interface to the Linux timerfd_settime(2) system
		2117	call. Please refer to its manpage for more info on this call.
		2118
		2119	The new itimerspec is specified using two (possibly fractional)
		2120	second values, $new_interval and $new_value).
		2121
		2122	On success, the current interval and value are returned (as per
		2123	"timerfd_gettime"). On failure, the empty list is returned.
		2124
		2125	The following $flags values are available:
		2126	"IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
		2127
		2128	See "IO::AIO::timerfd_create" for a full example.
		2129
		2130	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2131	This is a direct interface to the Linux timerfd_gettime(2) system
		2132	call. Please refer to its manpage for more info on this call.
		2133
		2134	On success, returns the current values of interval and value for the
		2135	given timerfd (as potentially fractional second values). On failure,
		2136	the empty list is returned.
1666		2137
1667	EVENT LOOP INTEGRATION	2138	EVENT LOOP INTEGRATION
1668	It is recommended to use AnyEvent::AIO to integrate IO::AIO	2139	It is recommended to use AnyEvent::AIO to integrate IO::AIO
1669	automatically into many event loops:	2140	automatically into many event loops:
1670		2141
…		…
1720	forking, if "IO::AIO" was used in the parent. Calling it while	2191	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.	2192	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)	2193	Calling it at any time will also result in any undefined (by POSIX)
1723	behaviour.	2194	behaviour.
1724		2195
		2196	LINUX-SPECIFIC CALLS
		2197	When a call is documented as "linux-specific" then this means it
		2198	originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
		2199	availability and compatibility of such calls regardless of the platform
		2200	it is compiled on, so platforms such as FreeBSD which often implement
		2201	these calls will work. When in doubt, call them and see if they fail wth
		2202	"ENOSYS".
		2203
1725	MEMORY USAGE	2204	MEMORY USAGE
1726	Per-request usage:	2205	Per-request usage:
1727		2206
1728	Each aio request uses - depending on your architecture - around 100-200	2207	Each aio request uses - depending on your architecture - around 100-200
1729	bytes of memory. In addition, stat requests need a stat buffer (possibly	2208	bytes of memory. In addition, stat requests need a stat buffer (possibly
…		…
1739	In the execution phase, some aio requests require more memory for	2218	In the execution phase, some aio requests require more memory for
1740	temporary buffers, and each thread requires a stack and other data	2219	temporary buffers, and each thread requires a stack and other data
1741	structures (usually around 16k-128k, depending on the OS).	2220	structures (usually around 16k-128k, depending on the OS).
1742		2221
1743	KNOWN BUGS	2222	KNOWN BUGS
1744	Known bugs will be fixed in the next release.	2223	Known bugs will be fixed in the next release :)
		2224
		2225	KNOWN ISSUES
		2226	Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
		2227	or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
		2228	non-created hash slots or other scalars I didn't think of. It's best to
		2229	avoid such and either use scalar variables or making sure that the
		2230	scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
		2231
		2232	I am not sure anything can be done about this, so this is considered a
		2233	known issue, rather than a bug.
1745		2234
1746	SEE ALSO	2235	SEE ALSO
1747	AnyEvent::AIO for easy integration into event loops, Coro::AIO for a	2236	AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1748	more natural syntax.	2237	more natural syntax and IO::FDPass for file descriptor passing.
1749		2238
1750	AUTHOR	2239	AUTHOR
1751	Marc Lehmann <schmorp@schmorp.de>	2240	Marc Lehmann <schmorp@schmorp.de>
1752	http://home.schmorp.de/	2241	http://home.schmorp.de/
1753		2242

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Revision 1.68 by root, Mon Sep 5 00:04:07 2022 UTC