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

Comparing IO-AIO/README (file contents):
Revision 1.55 by root, Sat Jan 25 00:15:52 2014 UTC vs.
Revision 1.71 by root, Fri Feb 16 21:20:52 2024 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
…		…
90		94
91	# file contents now in $contents	95	# file contents now in $contents
92	print $contents;	96	print $contents;
93		97
94	# exit event loop and program	98	# exit event loop and program
95	EV::unloop;	99	EV::break;
96	};	100	};
97	};	101	};
98		102
99	# possibly queue up other requests, or open GUI windows,	103	# possibly queue up other requests, or open GUI windows,
100	# check for sockets etc. etc.	104	# check for sockets etc. etc.
101		105
102	# process events as long as there are some:	106	# process events as long as there are some:
103	EV::loop;	107	EV::run;
104		108
105	REQUEST ANATOMY AND LIFETIME	109	REQUEST ANATOMY AND LIFETIME
106	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
107	not directly visible to Perl.	111	not directly visible to Perl.
108		112
…		…
171	aio_unlink $pathname, $callback->($status)	175	aio_unlink $pathname, $callback->($status)
172	aio_mknod $pathname, $mode, $dev, $callback->($status)	176	aio_mknod $pathname, $mode, $dev, $callback->($status)
173	aio_link $srcpath, $dstpath, $callback->($status)	177	aio_link $srcpath, $dstpath, $callback->($status)
174	aio_symlink $srcpath, $dstpath, $callback->($status)	178	aio_symlink $srcpath, $dstpath, $callback->($status)
175	aio_readlink $pathname, $callback->($link)	179	aio_readlink $pathname, $callback->($link)
176	aio_realpath $pathname, $callback->($link)	180	aio_realpath $pathname, $callback->($path)
177	aio_rename $srcpath, $dstpath, $callback->($status)	181	aio_rename $srcpath, $dstpath, $callback->($status)
		182	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
178	aio_mkdir $pathname, $mode, $callback->($status)	183	aio_mkdir $pathname, $mode, $callback->($status)
179	aio_rmdir $pathname, $callback->($status)	184	aio_rmdir $pathname, $callback->($status)
180	aio_readdir $pathname, $callback->($entries)	185	aio_readdir $pathname, $callback->($entries)
181	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	186	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
182	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	187	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
…		…
184	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)	189	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
185	aio_load $pathname, $data, $callback->($status)	190	aio_load $pathname, $data, $callback->($status)
186	aio_copy $srcpath, $dstpath, $callback->($status)	191	aio_copy $srcpath, $dstpath, $callback->($status)
187	aio_move $srcpath, $dstpath, $callback->($status)	192	aio_move $srcpath, $dstpath, $callback->($status)
188	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)
189	aio_sync $callback->($status)	196	aio_sync $callback->($status)
190	aio_syncfs $fh, $callback->($status)	197	aio_syncfs $fh, $callback->($status)
191	aio_fsync $fh, $callback->($status)	198	aio_fsync $fh, $callback->($status)
192	aio_fdatasync $fh, $callback->($status)	199	aio_fdatasync $fh, $callback->($status)
193	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	200	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
194	aio_pathsync $pathname, $callback->($status)	201	aio_pathsync $pathname, $callback->($status)
195	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	202	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
196	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	203	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
197	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	204	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
198	aio_mlockall $flags, $callback->($status)	205	aio_mlockall $flags, $callback->($status)
199	aio_group $callback->(...)	206	aio_group $callback->(...)
200	aio_nop $callback->()	207	aio_nop $callback->()
…		…
214	IO::AIO::idle_timeout $seconds	221	IO::AIO::idle_timeout $seconds
215	IO::AIO::max_outstanding $maxreqs	222	IO::AIO::max_outstanding $maxreqs
216	IO::AIO::nreqs	223	IO::AIO::nreqs
217	IO::AIO::nready	224	IO::AIO::nready
218	IO::AIO::npending	225	IO::AIO::npending
		226	IO::AIO::reinit
		227
		228	$nfd = IO::AIO::get_fdlimit
		229	IO::AIO::min_fdlimit $nfd
219		230
220	IO::AIO::sendfile $ofh, $ifh, $offset, $count	231	IO::AIO::sendfile $ofh, $ifh, $offset, $count
221	IO::AIO::fadvise $fh, $offset, $len, $advice	232	IO::AIO::fadvise $fh, $offset, $len, $advice
		233	IO::AIO::fexecve $fh, $argv, $envp
		234
222	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]	235	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
223	IO::AIO::munmap $scalar	236	IO::AIO::munmap $scalar
		237	IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
224	IO::AIO::madvise $scalar, $offset, $length, $advice	238	IO::AIO::madvise $scalar, $offset, $length, $advice
225	IO::AIO::mprotect $scalar, $offset, $length, $protect	239	IO::AIO::mprotect $scalar, $offset, $length, $protect
226	IO::AIO::munlock $scalar, $offset = 0, $length = undef	240	IO::AIO::munlock $scalar, $offset = 0, $length = undef
227	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
228		272
229	API NOTES	273	API NOTES
230	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
231	with the same name (sans "aio_"). The arguments are similar or	275	with the same name (sans "aio_"). The arguments are similar or
232	identical, and they all accept an additional (and optional) $callback	276	identical, and they all accept an additional (and optional) $callback
…		…
299	aio_open $pathname, $flags, $mode, $callback->($fh)	343	aio_open $pathname, $flags, $mode, $callback->($fh)
300	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
301	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
302	error).	346	error).
303		347
304	The pathname passed to "aio_open" must be absolute. See API NOTES,
305	above, for an explanation.
306
307	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.
308	They are the same as used by "sysopen".	349	They are the same as used by "sysopen".
309		350
310	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
311	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
…		…
330	"O_APPEND"), the following POSIX and non-POSIX constants are	371	"O_APPEND"), the following POSIX and non-POSIX constants are
331	available (missing ones on your system are, as usual, 0):	372	available (missing ones on your system are, as usual, 0):
332		373
333	"O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",	374	"O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
334	"O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",	375	"O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
335	"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".
336		378
337	aio_close $fh, $callback->($status)	379	aio_close $fh, $callback->($status)
338	Asynchronously close a file and call the callback with the result	380	Asynchronously close a file and call the callback with the result
339	code.	381	code.
340		382
…		…
370		412
371	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	413	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
372	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	414	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
373	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
374	$offset into the scalar given by $data and offset $dataoffset and	416	$offset into the scalar given by $data and offset $dataoffset and
375	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
376	error, just like the syscall).	418	-1 on error, just like the syscall).
377		419
378	"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
379	offset plus the actual number of bytes read.	421	offset plus the actual number of bytes read.
380		422
381	If $offset is undefined, then the current file descriptor offset	423	If $offset is undefined, then the current file descriptor offset
…		…
438	As native sendfile syscalls (as practically any non-POSIX interface	480	As native sendfile syscalls (as practically any non-POSIX interface
439	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
440	rather buggy on many systems, this implementation tries to work	482	rather buggy on many systems, this implementation tries to work
441	around some known bugs in Linux and FreeBSD kernels (probably	483	around some known bugs in Linux and FreeBSD kernels (probably
442	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
443	the return value of "aio_sendfile" - fewre bytes than expected might	485	the return value of "aio_sendfile" - fewer bytes than expected might
444	have been transferred.	486	have been transferred.
445		487
446	aio_readahead $fh,$offset,$length, $callback->($retval)	488	aio_readahead $fh,$offset,$length, $callback->($retval)
447	"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
448	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
…		…
452	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
453	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
454	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
455	is left unchanged.	497	is left unchanged.
456		498
457	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
458	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
459	similar effect.	501	similar effect.
460		502
461	aio_stat $fh_or_path, $callback->($status)	503	aio_stat $fh_or_path, $callback->($status)
462	aio_lstat $fh, $callback->($status)	504	aio_lstat $fh, $callback->($status)
463	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.
464	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
465	using "stat _" or "-s _" etc...	507	available using "stat _" or "-s _" and other tests (with the
466		508	exception of "-B" and "-T").
467	The pathname passed to "aio_stat" must be absolute. See API NOTES,
468	above, for an explanation.
469		509
470	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
471	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
472	silently truncated unless perl itself is compiled with large file	512	silently truncated unless perl itself is compiled with large file
473	support.	513	support.
…		…
478	back on traditional behaviour).	518	back on traditional behaviour).
479		519
480	"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",
481	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",	521	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
482	"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".
483		526
484	Example: Print the length of /etc/passwd:	527	Example: Print the length of /etc/passwd:
485		528
486	aio_stat "/etc/passwd", sub {	529	aio_stat "/etc/passwd", sub {
487	$_[0] and die "stat failed: $!";	530	$_[0] and die "stat failed: $!";
…		…
529	namemax => 255,	572	namemax => 255,
530	frsize => 1024,	573	frsize => 1024,
531	fsid => 1810	574	fsid => 1810
532	}	575	}
533		576
534	Here is a (likely partial - send me updates!) list of fsid values
535	used by Linux - it is safe to hardcode these when $^O is "linux":
536
537	0x0000adf5 adfs
538	0x0000adff affs
539	0x5346414f afs
540	0x09041934 anon-inode filesystem
541	0x00000187 autofs
542	0x42465331 befs
543	0x1badface bfs
544	0x42494e4d binfmt_misc
545	0x9123683e btrfs
546	0x0027e0eb cgroupfs
547	0xff534d42 cifs
548	0x73757245 coda
549	0x012ff7b7 coh
550	0x28cd3d45 cramfs
551	0x453dcd28 cramfs-wend (wrong endianness)
552	0x64626720 debugfs
553	0x00001373 devfs
554	0x00001cd1 devpts
555	0x0000f15f ecryptfs
556	0x00414a53 efs
557	0x0000137d ext
558	0x0000ef53 ext2/ext3
559	0x0000ef51 ext2
560	0x00004006 fat
561	0x65735546 fuseblk
562	0x65735543 fusectl
563	0x0bad1dea futexfs
564	0x01161970 gfs2
565	0x47504653 gpfs
566	0x00004244 hfs
567	0xf995e849 hpfs
568	0x958458f6 hugetlbfs
569	0x2bad1dea inotifyfs
570	0x00009660 isofs
571	0x000072b6 jffs2
572	0x3153464a jfs
573	0x6b414653 k-afs
574	0x0bd00bd0 lustre
575	0x0000137f minix
576	0x0000138f minix 30 char names
577	0x00002468 minix v2
578	0x00002478 minix v2 30 char names
579	0x00004d5a minix v3
580	0x19800202 mqueue
581	0x00004d44 msdos
582	0x0000564c novell
583	0x00006969 nfs
584	0x6e667364 nfsd
585	0x00003434 nilfs
586	0x5346544e ntfs
587	0x00009fa1 openprom
588	0x7461636F ocfs2
589	0x00009fa0 proc
590	0x6165676c pstorefs
591	0x0000002f qnx4
592	0x858458f6 ramfs
593	0x52654973 reiserfs
594	0x00007275 romfs
595	0x67596969 rpc_pipefs
596	0x73636673 securityfs
597	0xf97cff8c selinux
598	0x0000517b smb
599	0x534f434b sockfs
600	0x73717368 squashfs
601	0x62656572 sysfs
602	0x012ff7b6 sysv2
603	0x012ff7b5 sysv4
604	0x01021994 tmpfs
605	0x15013346 udf
606	0x00011954 ufs
607	0x54190100 ufs byteswapped
608	0x00009fa2 usbdevfs
609	0x01021997 v9fs
610	0xa501fcf5 vxfs
611	0xabba1974 xenfs
612	0x012ff7b4 xenix
613	0x58465342 xfs
614	0x012fd16d xia
615
616	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	577	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
617	Works like perl's "utime" function (including the special case of	578	Works like perl's "utime" function (including the special case of
618	$atime and $mtime being undef). Fractional times are supported if	579	$atime and $mtime being undef). Fractional times are supported if
619	the underlying syscalls support them.	580	the underlying syscalls support them.
620		581
621	When called with a pathname, uses utimes(2) if available, otherwise	582	When called with a pathname, uses utimensat(2) or utimes(2) if
622	utime(2). If called on a file descriptor, uses futimes(2) if	583	available, otherwise utime(2). If called on a file descriptor, uses
623	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.
624		586
625	Examples:	587	Examples:
626		588
627	# set atime and mtime to current time (basically touch(1)):	589	# set atime and mtime to current time (basically touch(1)):
628	aio_utime "path", undef, undef;	590	aio_utime "path", undef, undef;
…		…
643		605
644	aio_truncate $fh_or_path, $offset, $callback->($status)	606	aio_truncate $fh_or_path, $offset, $callback->($status)
645	Works like truncate(2) or ftruncate(2).	607	Works like truncate(2) or ftruncate(2).
646		608
647	aio_allocate $fh, $mode, $offset, $len, $callback->($status)	609	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
648	Allocates or freed disk space according to the $mode argument. See	610	Allocates or frees disk space according to the $mode argument. See
649	the linux "fallocate" docuemntation for details.	611	the linux "fallocate" documentation for details.
650		612
651	$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
652	allocate space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE \|	614	space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE \|
653	IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.	615	IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
654		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
655	The file system block size used by "fallocate" is presumably the	623	The file system block size used by "fallocate" is presumably the
656	"f_bsize" returned by "statvfs".	624	"f_bsize" returned by "statvfs", but different filesystems and
		625	filetypes can dictate other limitations.
657		626
658	If "fallocate" isn't available or cannot be emulated (currently no	627	If "fallocate" isn't available or cannot be emulated (currently no
659	emulation will be attempted), passes -1 and sets $! to "ENOSYS".	628	emulation will be attempted), passes -1 and sets $! to "ENOSYS".
660		629
661	aio_chmod $fh_or_path, $mode, $callback->($status)	630	aio_chmod $fh_or_path, $mode, $callback->($status)
…		…
705		674
706	On systems that support the AIO::WD working directory abstraction	675	On systems that support the AIO::WD working directory abstraction
707	natively, the case "[$wd, "."]" as $srcpath is specialcased -	676	natively, the case "[$wd, "."]" as $srcpath is specialcased -
708	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.
709		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
710	aio_mkdir $pathname, $mode, $callback->($status)	694	aio_mkdir $pathname, $mode, $callback->($status)
711	Asynchronously mkdir (create) a directory and call the callback with	695	Asynchronously mkdir (create) a directory and call the callback with
712	the result code. $mode will be modified by the umask at the time the	696	the result code. $mode will be modified by the umask at the time the
713	request is executed, so do not change your umask.	697	request is executed, so do not change your umask.
714		698
…		…
736	The flags are a combination of the following constants, ORed	720	The flags are a combination of the following constants, ORed
737	together (the flags will also be passed to the callback, possibly	721	together (the flags will also be passed to the callback, possibly
738	modified):	722	modified):
739		723
740	IO::AIO::READDIR_DENTS	724	IO::AIO::READDIR_DENTS
741	When this flag is off, then the callback gets an arrayref	725	Normally the callback gets an arrayref consisting of names only
742	consisting of names only (as with "aio_readdir"), otherwise it	726	(as with "aio_readdir"). If this flag is set, then the callback
743	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each	727	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
744	describing a single directory entry in more detail.	728	describing a single directory entry in more detail:
745		729
746	$name is the name of the entry.	730	$name is the name of the entry.
747		731
748	$type is one of the "IO::AIO::DT_xxx" constants:	732	$type is one of the "IO::AIO::DT_xxx" constants:
749		733
750	"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",
751	"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",
752	"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".
753		737
754	"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
755	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
756	reasons, the $type scalars are read-only: you can not modify	740	speed/memory reasons, the $type scalars are read-only: you must
757	them.	741	not modify them.
758		742
759	$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
760	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
761	unspecified content on systems that do not deliver the inode	745	unspecified content on systems that do not deliver the inode
762	information.	746	information.
…		…
774	of which names with short names are tried first.	758	of which names with short names are tried first.
775		759
776	IO::AIO::READDIR_STAT_ORDER	760	IO::AIO::READDIR_STAT_ORDER
777	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
778	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
779	to stat() all files in the given directory, then the returned	763	to stat() most or all files in the given directory, then the
780	order will likely be fastest.	764	returned order will likely be faster.
781		765
782	If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are	766	If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
783	specified, then the likely dirs come first, resulting in a less	767	specified, then the likely dirs come first, resulting in a less
784	optimal stat order.	768	optimal stat order for stat'ing all entries, but likely a more
		769	optimal order for finding subdirectories.
785		770
786	IO::AIO::READDIR_FOUND_UNKNOWN	771	IO::AIO::READDIR_FOUND_UNKNOWN
787	This flag should not be set when calling "aio_readdirx".	772	This flag should not be set when calling "aio_readdirx".
788	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
789	$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
790	flag therefore indicates that all $type's are known, which can	775	flag therefore indicates that all $type's are known, which can
791	be used to speed up some algorithms.	776	be used to speed up some algorithms.
792		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
793	aio_load $pathname, $data, $callback->($status)	805	aio_load $pathname, $data, $callback->($status)
794	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
795	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.
796		811
797	aio_copy $srcpath, $dstpath, $callback->($status)	812	aio_copy $srcpath, $dstpath, $callback->($status)
798	Try to copy the file (directories not supported as either source	813	Try to copy the file (directories not supported as either source
799	or destination) from $srcpath to $dstpath and call the callback with	814	or destination) from $srcpath to $dstpath and call the callback with
800	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.
801		818
802	This is a composite request that creates the destination file with	819	This is a composite request that creates the destination file with
803	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
804	"aio_sendfile", followed by restoring atime, mtime, access mode and	821	"aio_sendfile", followed by restoring atime, mtime, access mode and
805	uid/gid, in that order.	822	uid/gid, in that order.
…		…
822	to efficiently separate the entries of directory $path into two sets	839	to efficiently separate the entries of directory $path into two sets
823	of names, directories you can recurse into (directories), and ones	840	of names, directories you can recurse into (directories), and ones
824	you cannot recurse into (everything else, including symlinks to	841	you cannot recurse into (everything else, including symlinks to
825	directories).	842	directories).
826		843
827	"aio_scandir" is a composite request that creates of many sub	844	"aio_scandir" is a composite request that generates many sub
828	requests_ $maxreq specifies the maximum number of outstanding aio	845	requests. $maxreq specifies the maximum number of outstanding aio
829	requests that this function generates. If it is "<= 0", then a	846	requests that this function generates. If it is "<= 0", then a
830	suitable default will be chosen (currently 4).	847	suitable default will be chosen (currently 4).
831		848
832	On error, the callback is called without arguments, otherwise it	849	On error, the callback is called without arguments, otherwise it
833	receives two array-refs with path-relative entry names.	850	receives two array-refs with path-relative entry names.
…		…
840	print "everything else: @$nondirs\n";	857	print "everything else: @$nondirs\n";
841	};	858	};
842		859
843	Implementation notes.	860	Implementation notes.
844		861
845	The "aio_readdir" cannot be avoided, but "stat()"'ing every entry	862	The "aio_readdir" cannot be avoided, but stat()'ing every entry can.
846	can.
847		863
848	If readdir returns file type information, then this is used directly	864	If readdir returns file type information, then this is used directly
849	to find directories.	865	to find directories.
850		866
851	Otherwise, after reading the directory, the modification time, size	867	Otherwise, after reading the directory, the modification time, size
…		…
880	Delete a directory tree starting (and including) $path, return the	896	Delete a directory tree starting (and including) $path, return the
881	status of the final "rmdir" only. This is a composite request that	897	status of the final "rmdir" only. This is a composite request that
882	uses "aio_scandir" to recurse into and rmdir directories, and unlink	898	uses "aio_scandir" to recurse into and rmdir directories, and unlink
883	everything else.	899	everything else.
884		900
		901	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		902	aio_ioctl $fh, $request, $buf, $callback->($status)
		903	These work just like the "fcntl" and "ioctl" built-in functions,
		904	except they execute asynchronously and pass the return value to the
		905	callback.
		906
		907	Both calls can be used for a lot of things, some of which make more
		908	sense to run asynchronously in their own thread, while some others
		909	make less sense. For example, calls that block waiting for external
		910	events, such as locking, will also lock down an I/O thread while it
		911	is waiting, which can deadlock the whole I/O system. At the same
		912	time, there might be no alternative to using a thread to wait.
		913
		914	So in general, you should only use these calls for things that do
		915	(filesystem) I/O, not for things that wait for other events
		916	(network, other processes), although if you are careful and know
		917	what you are doing, you still can.
		918
		919	The following constants are available and can be used for normal
		920	"ioctl" and "fcntl" as well (missing ones are, as usual 0):
		921
		922	"F_DUPFD_CLOEXEC",
		923
		924	"F_OFD_GETLK", "F_OFD_SETLK", "F_OFD_GETLKW",
		925
		926	"FIFREEZE", "FITHAW", "FITRIM", "FICLONE", "FICLONERANGE",
		927	"FIDEDUPERANGE".
		928
		929	"F_ADD_SEALS", "F_GET_SEALS", "F_SEAL_SEAL", "F_SEAL_SHRINK",
		930	"F_SEAL_GROW" and "F_SEAL_WRITE".
		931
		932	"FS_IOC_GETFLAGS", "FS_IOC_SETFLAGS", "FS_IOC_GETVERSION",
		933	"FS_IOC_SETVERSION", "FS_IOC_FIEMAP".
		934
		935	"FS_IOC_FSGETXATTR", "FS_IOC_FSSETXATTR",
		936	"FS_IOC_SET_ENCRYPTION_POLICY", "FS_IOC_GET_ENCRYPTION_PWSALT",
		937	"FS_IOC_GET_ENCRYPTION_POLICY", "FS_KEY_DESCRIPTOR_SIZE".
		938
		939	"FS_SECRM_FL", "FS_UNRM_FL", "FS_COMPR_FL", "FS_SYNC_FL",
		940	"FS_IMMUTABLE_FL", "FS_APPEND_FL", "FS_NODUMP_FL", "FS_NOATIME_FL",
		941	"FS_DIRTY_FL", "FS_COMPRBLK_FL", "FS_NOCOMP_FL", "FS_ENCRYPT_FL",
		942	"FS_BTREE_FL", "FS_INDEX_FL", "FS_JOURNAL_DATA_FL", "FS_NOTAIL_FL",
		943	"FS_DIRSYNC_FL", "FS_TOPDIR_FL", "FS_FL_USER_MODIFIABLE".
		944
		945	"FS_XFLAG_REALTIME", "FS_XFLAG_PREALLOC", "FS_XFLAG_IMMUTABLE",
		946	"FS_XFLAG_APPEND", "FS_XFLAG_SYNC", "FS_XFLAG_NOATIME",
		947	"FS_XFLAG_NODUMP", "FS_XFLAG_RTINHERIT", "FS_XFLAG_PROJINHERIT",
		948	"FS_XFLAG_NOSYMLINKS", "FS_XFLAG_EXTSIZE", "FS_XFLAG_EXTSZINHERIT",
		949	"FS_XFLAG_NODEFRAG", "FS_XFLAG_FILESTREAM", "FS_XFLAG_DAX",
		950	"FS_XFLAG_HASATTR",
		951
		952	"BLKROSET", "BLKROGET", "BLKRRPART", "BLKGETSIZE", "BLKFLSBUF",
		953	"BLKRASET", "BLKRAGET", "BLKFRASET", "BLKFRAGET", "BLKSECTSET",
		954	"BLKSECTGET", "BLKSSZGET", "BLKBSZGET", "BLKBSZSET", "BLKGETSIZE64",
		955
885	aio_sync $callback->($status)	956	aio_sync $callback->($status)
886	Asynchronously call sync and call the callback when finished.	957	Asynchronously call sync and call the callback when finished.
887		958
888	aio_fsync $fh, $callback->($status)	959	aio_fsync $fh, $callback->($status)
889	Asynchronously call fsync on the given filehandle and call the	960	Asynchronously call fsync on the given filehandle and call the
…		…
925	Future versions of this function might fall back to other methods	996	Future versions of this function might fall back to other methods
926	when "fsync" on the directory fails (such as calling "sync").	997	when "fsync" on the directory fails (such as calling "sync").
927		998
928	Passes 0 when everything went ok, and -1 on error.	999	Passes 0 when everything went ok, and -1 on error.
929		1000
930	aio_msync $scalar, $offset = 0, $length = undef, flags = 0,	1001	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
931	$callback->($status)	1002	$callback->($status)
932	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
933	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
934	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,
935	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
…		…
937		1008
938	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
939	memory area starting at $offset in the string and ending $length	1010	memory area starting at $offset in the string and ending $length
940	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
941	$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
942	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
943	"IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".	1014	an optional "IO::AIO::MS_INVALIDATE".
944		1015
945	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,	1016	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
946	$callback->($status)	1017	$callback->($status)
947	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
948	mmap(2)ed scalars.	1019	mmap(2)ed scalars.
…		…
979	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;
980	aio_mlock $data; # mlock in background	1051	aio_mlock $data; # mlock in background
981		1052
982	aio_mlockall $flags, $callback->($status)	1053	aio_mlockall $flags, $callback->($status)
983	Calls the "mlockall" function with the given $flags (a combination	1054	Calls the "mlockall" function with the given $flags (a combination
984	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").
985		1057
986	On systems that do not implement "mlockall", this function returns	1058	On systems that do not implement "mlockall", this function returns
987	-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".
988		1062
989	Note that the corresponding "munlockall" is synchronous and is	1063	Note that the corresponding "munlockall" is synchronous and is
990	documented under "MISCELLANEOUS FUNCTIONS".	1064	documented under "MISCELLANEOUS FUNCTIONS".
991		1065
992	Example: asynchronously lock all current and future pages into	1066	Example: asynchronously lock all current and future pages into
…		…
1034	"IO::AIO::FIEMAP_EXTENT_DATA_INLINE",	1108	"IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1035	"IO::AIO::FIEMAP_EXTENT_DATA_TAIL",	1109	"IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1036	"IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"	1110	"IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1037	or "IO::AIO::FIEMAP_EXTENT_SHARED".	1111	or "IO::AIO::FIEMAP_EXTENT_SHARED".
1038		1112
1039	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
1040	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
1041	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
1042	number of extents. The code works around all these issues if $count	1116	large number of extents. The code (only) works around all these
1043	is undef.	1117	issues if $count is "undef".
1044		1118
1045	aio_group $callback->(...)	1119	aio_group $callback->(...)
1046	This is a very special aio request: Instead of doing something, it	1120	This is a very special aio request: Instead of doing something, it
1047	is a container for other aio requests, which is useful if you want	1121	is a container for other aio requests, which is useful if you want
1048	to bundle many requests into a single, composite, request with a	1122	to bundle many requests into a single, composite, request with a
…		…
1128	aio_stat [$etcdir, "passwd"], sub {	1202	aio_stat [$etcdir, "passwd"], sub {
1129	# yay	1203	# yay
1130	};	1204	};
1131	};	1205	};
1132		1206
1133	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
1134	an IO::AIO::WD object is itself a potentially blocking operation, which	1208	creating an IO::AIO::WD object is itself a potentially blocking
1135	is why it is done asynchronously.	1209	operation, which is why it is done asynchronously.
1136		1210
1137	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
1138	either of the following three request calls:	1212	either of the following three request calls:
1139		1213
1140	aio_lstat "/etc" , sub { ... # pathname as normal string	1214	aio_lstat "/etc" , sub { ... # pathname as normal string
…		…
1157	There are some caveats: when directories get renamed (or deleted), the	1231	There are some caveats: when directories get renamed (or deleted), the
1158	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
1159	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,
1160	will still point to the original directory. Most functions accepting a	1234	will still point to the original directory. Most functions accepting a
1161	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
1162	older systems. Some functions (such as realpath) will always rely on the	1236	older systems. Some functions (such as "aio_realpath") will always rely
1163	string form of the pathname.	1237	on the string form of the pathname.
1164		1238
1165	So this functionality is mainly useful to get some protection against	1239	So this functionality is mainly useful to get some protection against
1166	"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
1167	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
1168	directory (e.g. when stat'ing all files in a directory).	1242	directory (e.g. when stat'ing all files in a directory).
…		…
1181	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
1182	checking in the "aio_wd" callback, as future requests using the	1256	checking in the "aio_wd" callback, as future requests using the
1183	value will fail in the expected way.	1257	value will fail in the expected way.
1184		1258
1185	IO::AIO::CWD	1259	IO::AIO::CWD
1186	This is a compiletime constant (object) that represents the process	1260	This is a compile time constant (object) that represents the process
1187	current working directory.	1261	current working directory.
1188		1262
1189	Specifying this object as working directory object for a pathname is	1263	Specifying this object as working directory object for a pathname is
1190	as if the pathname would be specified directly, without a directory	1264	as if the pathname would be specified directly, without a directory
1191	object. For example, these calls are functionally identical:	1265	object. For example, these calls are functionally identical:
…		…
1416	Strictly equivalent to:	1490	Strictly equivalent to:
1417		1491
1418	IO::AIO::poll_wait, IO::AIO::poll_cb	1492	IO::AIO::poll_wait, IO::AIO::poll_cb
1419	while IO::AIO::nreqs;	1493	while IO::AIO::nreqs;
1420		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
		1505
1421	IO::AIO::max_poll_reqs $nreqs	1506	IO::AIO::max_poll_reqs $nreqs
1422	IO::AIO::max_poll_time $seconds	1507	IO::AIO::max_poll_time $seconds
1423	These set the maximum number of requests (default 0, meaning	1508	These set the maximum number of requests (default 0, meaning
1424	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
1425	call, respectively the maximum amount of time (default 0, meaning	1510	call, respectively the maximum amount of time (default 0, meaning
…		…
1514	no longer exceeded.	1599	no longer exceeded.
1515		1600
1516	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
1517	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.
1518		1603
1519	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
1520	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.
1521	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.
1522		1609
1523	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
1524	stat a lot of files, you can write somehting like this:	1611	stat a lot of files, you can write something like this:
1525		1612
1526	IO::AIO::max_outstanding 32;	1613	IO::AIO::max_outstanding 32;
1527		1614
1528	for my $path (...) {	1615	for my $path (...) {
1529	aio_stat $path , ...;	1616	aio_stat $path , ...;
…		…
1531	}	1618	}
1532		1619
1533	IO::AIO::flush;	1620	IO::AIO::flush;
1534		1621
1535	The call to "poll_cb" inside the loop will normally return	1622	The call to "poll_cb" inside the loop will normally return
1536	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
1537	will block until some requests have been handled. This keeps the	1624	32 requests are in-flight, it will block until some requests have
1538	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
1539	queue.	1626	"aio_stat" requests onto the queue (which, with many paths to stat,
		1627	can use up a lot of memory).
1540		1628
1541	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
1542	no practical limit on the number of outstanding requests.	1630	no practical limit on the number of outstanding requests.
1543		1631
1544	STATISTICAL INFORMATION	1632	STATISTICAL INFORMATION
…		…
1558		1646
1559	IO::AIO::npending	1647	IO::AIO::npending
1560	Returns the number of requests currently in the pending state	1648	Returns the number of requests currently in the pending state
1561	(executed, but not yet processed by poll_cb).	1649	(executed, but not yet processed by poll_cb).
1562		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
1563	MISCELLANEOUS FUNCTIONS	1736	MISCELLANEOUS FUNCTIONS
1564	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
1565	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	$retval = IO::AIO::mount $special, $path, $fstype, $flags = 0, $data =
		1749	undef
		1750	Calls the GNU/Linux mount syscall with the given arguments. All
		1751	except $flags are strings, and if $data is "undef", a "NULL" will be
		1752	passed.
		1753
		1754	The following values for $flags are available:
		1755
		1756	"IO::AIO::MS_RDONLY", "IO::AIO::MS_NOSUID", "IO::AIO::MS_NODEV",
		1757	"IO::AIO::MS_NOEXEC", "IO::AIO::MS_SYNCHRONOUS",
		1758	"IO::AIO::MS_REMOUNT", "IO::AIO::MS_MANDLOCK",
		1759	"IO::AIO::MS_DIRSYNC", "IO::AIO::MS_NOATIME",
		1760	"IO::AIO::MS_NODIRATIME", "IO::AIO::MS_BIND", "IO::AIO::MS_MOVE",
		1761	"IO::AIO::MS_REC", "IO::AIO::MS_SILENT", "IO::AIO::MS_POSIXACL",
		1762	"IO::AIO::MS_UNBINDABLE", "IO::AIO::MS_PRIVATE",
		1763	"IO::AIO::MS_SLAVE", "IO::AIO::MS_SHARED", "IO::AIO::MS_RELATIME",
		1764	"IO::AIO::MS_KERNMOUNT", "IO::AIO::MS_I_VERSION",
		1765	"IO::AIO::MS_STRICTATIME", "IO::AIO::MS_LAZYTIME",
		1766	"IO::AIO::MS_ACTIVE", "IO::AIO::MS_NOUSER", "IO::AIO::MS_RMT_MASK",
		1767	"IO::AIO::MS_MGC_VAL" and "IO::AIO::MS_MGC_MSK".
		1768
		1769	$retval = IO::AIO::umount $path, $flags = 0
		1770	Invokes the GNU/Linux "umount" or "umount2" syscalls. Always calls
		1771	"umount" if $flags is 0, otherwqise always tries to call "umount2".
		1772
		1773	The following $flags are available:
		1774
		1775	"IO::AIO::MNT_FORCE", "IO::AIO::MNT_DETACH", "IO::AIO::MNT_EXPIRE"
		1776	and "IO::AIO::UMOUNT_NOFOLLOW".
		1777
		1778	$numfd = IO::AIO::get_fdlimit
		1779	Tries to find the current file descriptor limit and returns it, or
		1780	"undef" and sets $! in case of an error. The limit is one larger
		1781	than the highest valid file descriptor number.
		1782
		1783	IO::AIO::min_fdlimit [$numfd]
		1784	Try to increase the current file descriptor limit(s) to at least
		1785	$numfd by changing the soft or hard file descriptor resource limit.
		1786	If $numfd is missing, it will try to set a very high limit, although
		1787	this is not recommended when you know the actual minimum that you
		1788	require.
		1789
		1790	If the limit cannot be raised enough, the function makes a
		1791	best-effort attempt to increase the limit as much as possible, using
		1792	various tricks, while still failing. You can query the resulting
		1793	limit using "IO::AIO::get_fdlimit".
		1794
		1795	If an error occurs, returns "undef" and sets $!, otherwise returns
		1796	true.
1566		1797
1567	IO::AIO::sendfile $ofh, $ifh, $offset, $count	1798	IO::AIO::sendfile $ofh, $ifh, $offset, $count
1568	Calls the "eio_sendfile_sync" function, which is like	1799	Calls the "eio_sendfile_sync" function, which is like
1569	"aio_sendfile", but is blocking (this makes most sense if you know	1800	"aio_sendfile", but is blocking (this makes most sense if you know
1570	the input data is likely cached already and the output filehandle is	1801	the input data is likely cached already and the output filehandle is
…		…
1587	details). The following advice constants are available:	1818	details). The following advice constants are available:
1588	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",	1819	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1589	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",	1820	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1590	"IO::AIO::MADV_DONTNEED".	1821	"IO::AIO::MADV_DONTNEED".
1591		1822
		1823	If $offset is negative, counts from the end. If $length is negative,
		1824	the remaining length of the $scalar is used. If possible, $length
		1825	will be reduced to fit into the $scalar.
		1826
1592	On systems that do not implement "posix_madvise", this function	1827	On systems that do not implement "posix_madvise", this function
1593	returns ENOSYS, otherwise the return value of "posix_madvise".	1828	returns ENOSYS, otherwise the return value of "posix_madvise".
1594		1829
1595	IO::AIO::mprotect $scalar, $offset, $len, $protect	1830	IO::AIO::mprotect $scalar, $offset, $len, $protect
1596	Simply calls the "mprotect" function on the preferably AIO::mmap'ed	1831	Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1597	$scalar (see its manpage for details). The following protect	1832	$scalar (see its manpage for details). The following protect
1598	constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",	1833	constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1599	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".	1834	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1600		1835
		1836	If $offset is negative, counts from the end. If $length is negative,
		1837	the remaining length of the $scalar is used. If possible, $length
		1838	will be reduced to fit into the $scalar.
		1839
1601	On systems that do not implement "mprotect", this function returns	1840	On systems that do not implement "mprotect", this function returns
1602	ENOSYS, otherwise the return value of "mprotect".	1841	ENOSYS, otherwise the return value of "mprotect".
1603		1842
1604	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	1843	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1605	Memory-maps a file (or anonymous memory range) and attaches it to	1844	Memory-maps a file (or anonymous memory range) and attaches it to
1606	the given $scalar, which will act like a string scalar. Returns true	1845	the given $scalar, which will act like a string scalar. Returns true
1607	on success, and false otherwise.	1846	on success, and false otherwise.
1608		1847
		1848	The scalar must exist, but its contents do not matter - this means
		1849	you cannot use a nonexistant array or hash element. When in doubt,
		1850	"undef" the scalar first.
		1851
1609	The only operations allowed on the scalar are "substr"/"vec" that	1852	The only operations allowed on the mmapped scalar are
1610	don't change the string length, and most read-only operations such	1853	"substr"/"vec", which don't change the string length, and most
1611	as copying it or searching it with regexes and so on.	1854	read-only operations such as copying it or searching it with regexes
		1855	and so on.
1612		1856
1613	Anything else is unsafe and will, at best, result in memory leaks.	1857	Anything else is unsafe and will, at best, result in memory leaks.
1614		1858
1615	The memory map associated with the $scalar is automatically removed	1859	The memory map associated with the $scalar is automatically removed
1616	when the $scalar is destroyed, or when the "IO::AIO::mmap" or	1860	when the $scalar is undef'd or destroyed, or when the
1617	"IO::AIO::munmap" functions are called.	1861	"IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1618		1862
1619	This calls the "mmap"(2) function internally. See your system's	1863	This calls the "mmap"(2) function internally. See your system's
1620	manual page for details on the $length, $prot and $flags parameters.	1864	manual page for details on the $length, $prot and $flags parameters.
1621		1865
1622	The $length must be larger than zero and smaller than the actual	1866	The $length must be larger than zero and smaller than the actual
…		…
1626	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or	1870	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1627	"IO::AIO::PROT_WRITE",	1871	"IO::AIO::PROT_WRITE",
1628		1872
1629	$flags can be a combination of "IO::AIO::MAP_SHARED" or	1873	$flags can be a combination of "IO::AIO::MAP_SHARED" or
1630	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when	1874	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1631	not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"	1875	not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1632	(which is set to "MAP_ANON" if your system only provides this	1876	"MAP_ANON" if your system only provides this constant),
		1877	"IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1633	constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",	1878	"IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1634	"IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or	1879	"IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1635	"IO::AIO::MAP_NONBLOCK"	1880	"IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_STACK",
		1881	"IO::AIO::MAP_FIXED_NOREPLACE", "IO::AIO::MAP_SHARED_VALIDATE",
		1882	"IO::AIO::MAP_SYNC" or "IO::AIO::MAP_UNINITIALIZED".
1636		1883
1637	If $fh is "undef", then a file descriptor of -1 is passed.	1884	If $fh is "undef", then a file descriptor of -1 is passed.
1638		1885
1639	$offset is the offset from the start of the file - it generally must	1886	$offset is the offset from the start of the file - it generally must
1640	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.	1887	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
…		…
1652		1899
1653	my $fast_md5 = md5 $data;	1900	my $fast_md5 = md5 $data;
1654		1901
1655	IO::AIO::munmap $scalar	1902	IO::AIO::munmap $scalar
1656	Removes a previous mmap and undefines the $scalar.	1903	Removes a previous mmap and undefines the $scalar.
		1904
		1905	IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[,
		1906	$new_address = 0]
		1907	Calls the Linux-specific mremap(2) system call. The $scalar must
		1908	have been mapped by "IO::AIO::mmap", and $flags must currently
		1909	either be 0 or "IO::AIO::MREMAP_MAYMOVE".
		1910
		1911	Returns true if successful, and false otherwise. If the underlying
		1912	mmapped region has changed address, then the true value has the
		1913	numerical value 1, otherwise it has the numerical value 0:
		1914
		1915	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		1916	or die "mremap: $!";
		1917
		1918	if ($success*1) {
		1919	warn "scalar has chanegd address in memory\n";
		1920	}
		1921
		1922	"IO::AIO::MREMAP_FIXED" and the $new_address argument are currently
		1923	implemented, but not supported and might go away in a future
		1924	version.
		1925
		1926	On systems where this call is not supported or is not emulated, this
		1927	call returns falls and sets $! to "ENOSYS".
		1928
		1929	IO::AIO::mlockall $flags
		1930	Calls the "eio_mlockall_sync" function, which is like
		1931	"aio_mlockall", but is blocking.
1657		1932
1658	IO::AIO::munlock $scalar, $offset = 0, $length = undef	1933	IO::AIO::munlock $scalar, $offset = 0, $length = undef
1659	Calls the "munlock" function, undoing the effects of a previous	1934	Calls the "munlock" function, undoing the effects of a previous
1660	"aio_mlock" call (see its description for details).	1935	"aio_mlock" call (see its description for details).
1661		1936
1662	IO::AIO::munlockall	1937	IO::AIO::munlockall
1663	Calls the "munlockall" function.	1938	Calls the "munlockall" function.
1664		1939
1665	On systems that do not implement "munlockall", this function returns	1940	On systems that do not implement "munlockall", this function returns
1666	ENOSYS, otherwise the return value of "munlockall".	1941	ENOSYS, otherwise the return value of "munlockall".
		1942
		1943	$fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		1944	Uses the GNU/Linux accept4(2) syscall, if available, to accept a
		1945	socket and return the new file handle on success, or sets $! and
		1946	returns "undef" on error.
		1947
		1948	The remote name of the new socket will be stored in $sockaddr, which
		1949	will be extended to allow for at least $sockaddr_maxlen octets. If
		1950	the socket name does not fit into $sockaddr_maxlen octets, this is
		1951	signaled by returning a longer string in $sockaddr, which might or
		1952	might not be truncated.
		1953
		1954	To accept name-less sockets, use "undef" for $sockaddr and 0 for
		1955	$sockaddr_maxlen.
		1956
		1957	The main reasons to use this syscall rather than portable accept(2)
		1958	are that you can specify "SOCK_NONBLOCK" and/or "SOCK_CLOEXEC" flags
		1959	and you can accept name-less sockets by specifying 0 for
		1960	$sockaddr_maxlen, which is sadly not possible with perl's interface
		1961	to "accept".
1667		1962
1668	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags	1963	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1669	Calls the GNU/Linux splice(2) syscall, if available. If $r_off or	1964	Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1670	$w_off are "undef", then "NULL" is passed for these, otherwise they	1965	$w_off are "undef", then "NULL" is passed for these, otherwise they
1671	should be the file offset.	1966	should be the file offset.
…		…
1678	"IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".	1973	"IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1679		1974
1680	See the splice(2) manpage for details.	1975	See the splice(2) manpage for details.
1681		1976
1682	IO::AIO::tee $r_fh, $w_fh, $length, $flags	1977	IO::AIO::tee $r_fh, $w_fh, $length, $flags
1683	Calls the GNU/Linux tee(2) syscall, see it's manpage and the	1978	Calls the GNU/Linux tee(2) syscall, see its manpage and the
1684	description for "IO::AIO::splice" above for details.	1979	description for "IO::AIO::splice" above for details.
1685		1980
1686	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]	1981	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
1687	Attempts to query or change the pipe buffer size. Obviously works	1982	Attempts to query or change the pipe buffer size. Obviously works
1688	only on pipes, and currently works only on GNU/Linux systems, and	1983	only on pipes, and currently works only on GNU/Linux systems, and
1689	fails with -1/"ENOSYS" everywhere else. If anybody knows how to	1984	fails with -1/"ENOSYS" everywhere else. If anybody knows how to
1690	influence pipe buffer size on other systems, drop me a note.	1985	influence pipe buffer size on other systems, drop me a note.
		1986
		1987	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		1988	This is a direct interface to the Linux pipe2(2) system call. If
		1989	$flags is missing or 0, then this should be the same as a call to
		1990	perl's built-in "pipe" function and create a new pipe, and works on
		1991	systems that lack the pipe2 syscall. On win32, this case invokes
		1992	"_pipe (..., 4096, O_BINARY)".
		1993
		1994	If $flags is non-zero, it tries to invoke the pipe2 system call with
		1995	the given flags (Linux 2.6.27, glibc 2.9).
		1996
		1997	On success, the read and write file handles are returned.
		1998
		1999	On error, nothing will be returned. If the pipe2 syscall is missing
		2000	and $flags is non-zero, fails with "ENOSYS".
		2001
		2002	Please refer to pipe2(2) for more info on the $flags, but at the
		2003	time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
		2004	and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
		2005	supported.
		2006
		2007	Example: create a pipe race-free w.r.t. threads and fork:
		2008
		2009	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2010	or die "pipe2: $!\n";
		2011
		2012	$fh = IO::AIO::memfd_create $pathname[, $flags]
		2013	This is a direct interface to the Linux memfd_create(2) system call.
		2014	The (unhelpful) default for $flags is 0, but your default should be
		2015	"IO::AIO::MFD_CLOEXEC".
		2016
		2017	On success, the new memfd filehandle is returned, otherwise returns
		2018	"undef". If the memfd_create syscall is missing, fails with
		2019	"ENOSYS".
		2020
		2021	Please refer to memfd_create(2) for more info on this call.
		2022
		2023	The following $flags values are available: "IO::AIO::MFD_CLOEXEC",
		2024	"IO::AIO::MFD_ALLOW_SEALING", "IO::AIO::MFD_HUGETLB",
		2025	"IO::AIO::MFD_HUGETLB_2MB" and "IO::AIO::MFD_HUGETLB_1GB".
		2026
		2027	Example: create a new memfd.
		2028
		2029	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2030	or die "memfd_create: $!\n";
		2031
		2032	$fh = IO::AIO::pidfd_open $pid[, $flags]
		2033	This is an interface to the Linux pidfd_open(2) system call. The
		2034	default for $flags is 0.
		2035
		2036	On success, a new pidfd filehandle is returned (that is already set
		2037	to close-on-exec), otherwise returns "undef". If the syscall is
		2038	missing, fails with "ENOSYS".
		2039
		2040	Example: open pid 6341 as pidfd.
		2041
		2042	my $fh = IO::AIO::pidfd_open 6341
		2043	or die "pidfd_open: $!\n";
		2044
		2045	$status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[,
		2046	$flags]]
		2047	This is an interface to the Linux pidfd_send_signal system call. The
		2048	default for $siginfo is "undef" and the default for $flags is 0.
		2049
		2050	Returns the system call status. If the syscall is missing, fails
		2051	with "ENOSYS".
		2052
		2053	When specified, $siginfo must be a reference to a hash with one or
		2054	more of the following members:
		2055
		2056	code - the "si_code" member
		2057	pid - the "si_pid" member
		2058	uid - the "si_uid" member
		2059	value_int - the "si_value.sival_int" member
		2060	value_ptr - the "si_value.sival_ptr" member, specified as an integer
		2061
		2062	Example: send a SIGKILL to the specified process.
		2063
		2064	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
		2065	and die "pidfd_send_signal: $!\n";
		2066
		2067	Example: send a SIGKILL to the specified process with extra data.
		2068
		2069	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
		2070	and die "pidfd_send_signal: $!\n";
		2071
		2072	$fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		2073	This is an interface to the Linux pidfd_getfd system call. The
		2074	default for $flags is 0.
		2075
		2076	On success, returns a dup'ed copy of the target file descriptor
		2077	(specified as an integer) returned (that is already set to
		2078	close-on-exec), otherwise returns "undef". If the syscall is
		2079	missing, fails with "ENOSYS".
		2080
		2081	Example: get a copy of standard error of another process and print
		2082	soemthing to it.
		2083
		2084	my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
		2085	or die "pidfd_getfd: $!\n";
		2086	print $errfh "stderr\n";
		2087
		2088	$fh = IO::AIO::eventfd [$initval, [$flags]]
		2089	This is a direct interface to the Linux eventfd(2) system call. The
		2090	(unhelpful) defaults for $initval and $flags are 0 for both.
		2091
		2092	On success, the new eventfd filehandle is returned, otherwise
		2093	returns "undef". If the eventfd syscall is missing, fails with
		2094	"ENOSYS".
		2095
		2096	Please refer to eventfd(2) for more info on this call.
		2097
		2098	The following symbol flag values are available:
		2099	"IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
		2100	"IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
		2101
		2102	Example: create a new eventfd filehandle:
		2103
		2104	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2105	or die "eventfd: $!\n";
		2106
		2107	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		2108	This is a direct interface to the Linux timerfd_create(2) system
		2109	call. The (unhelpful) default for $flags is 0, but your default
		2110	should be "IO::AIO::TFD_CLOEXEC".
		2111
		2112	On success, the new timerfd filehandle is returned, otherwise
		2113	returns "undef". If the timerfd_create syscall is missing, fails
		2114	with "ENOSYS".
		2115
		2116	Please refer to timerfd_create(2) for more info on this call.
		2117
		2118	The following $clockid values are available:
		2119	"IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
		2120	"IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
		2121	"IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
		2122	"IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
		2123
		2124	The following $flags values are available (Linux 2.6.27):
		2125	"IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
		2126
		2127	Example: create a new timerfd and set it to one-second repeated
		2128	alarms, then wait for two alarms:
		2129
		2130	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2131	or die "timerfd_create: $!\n";
		2132
		2133	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2134	or die "timerfd_settime: $!\n";
		2135
		2136	for (1..2) {
		2137	8 == sysread $fh, my $buf, 8
		2138	or die "timerfd read failure\n";
		2139
		2140	printf "number of expirations (likely 1): %d\n",
		2141	unpack "Q", $buf;
		2142	}
		2143
		2144	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
		2145	$new_interval, $nbw_value
		2146	This is a direct interface to the Linux timerfd_settime(2) system
		2147	call. Please refer to its manpage for more info on this call.
		2148
		2149	The new itimerspec is specified using two (possibly fractional)
		2150	second values, $new_interval and $new_value).
		2151
		2152	On success, the current interval and value are returned (as per
		2153	"timerfd_gettime"). On failure, the empty list is returned.
		2154
		2155	The following $flags values are available:
		2156	"IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
		2157
		2158	See "IO::AIO::timerfd_create" for a full example.
		2159
		2160	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2161	This is a direct interface to the Linux timerfd_gettime(2) system
		2162	call. Please refer to its manpage for more info on this call.
		2163
		2164	On success, returns the current values of interval and value for the
		2165	given timerfd (as potentially fractional second values). On failure,
		2166	the empty list is returned.
1691		2167
1692	EVENT LOOP INTEGRATION	2168	EVENT LOOP INTEGRATION
1693	It is recommended to use AnyEvent::AIO to integrate IO::AIO	2169	It is recommended to use AnyEvent::AIO to integrate IO::AIO
1694	automatically into many event loops:	2170	automatically into many event loops:
1695		2171
…		…
1745	forking, if "IO::AIO" was used in the parent. Calling it while	2221	forking, if "IO::AIO" was used in the parent. Calling it while
1746	IO::AIO is active in the process will result in undefined behaviour.	2222	IO::AIO is active in the process will result in undefined behaviour.
1747	Calling it at any time will also result in any undefined (by POSIX)	2223	Calling it at any time will also result in any undefined (by POSIX)
1748	behaviour.	2224	behaviour.
1749		2225
		2226	LINUX-SPECIFIC CALLS
		2227	When a call is documented as "linux-specific" then this means it
		2228	originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
		2229	availability and compatibility of such calls regardless of the platform
		2230	it is compiled on, so platforms such as FreeBSD which often implement
		2231	these calls will work. When in doubt, call them and see if they fail wth
		2232	"ENOSYS".
		2233
1750	MEMORY USAGE	2234	MEMORY USAGE
1751	Per-request usage:	2235	Per-request usage:
1752		2236
1753	Each aio request uses - depending on your architecture - around 100-200	2237	Each aio request uses - depending on your architecture - around 100-200
1754	bytes of memory. In addition, stat requests need a stat buffer (possibly	2238	bytes of memory. In addition, stat requests need a stat buffer (possibly
…		…
1764	In the execution phase, some aio requests require more memory for	2248	In the execution phase, some aio requests require more memory for
1765	temporary buffers, and each thread requires a stack and other data	2249	temporary buffers, and each thread requires a stack and other data
1766	structures (usually around 16k-128k, depending on the OS).	2250	structures (usually around 16k-128k, depending on the OS).
1767		2251
1768	KNOWN BUGS	2252	KNOWN BUGS
1769	Known bugs will be fixed in the next release.	2253	Known bugs will be fixed in the next release :)
		2254
		2255	KNOWN ISSUES
		2256	Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
		2257	or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
		2258	non-created hash slots or other scalars I didn't think of. It's best to
		2259	avoid such and either use scalar variables or making sure that the
		2260	scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
		2261
		2262	I am not sure anything can be done about this, so this is considered a
		2263	known issue, rather than a bug.
1770		2264
1771	SEE ALSO	2265	SEE ALSO
1772	AnyEvent::AIO for easy integration into event loops, Coro::AIO for a	2266	AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1773	more natural syntax.	2267	more natural syntax and IO::FDPass for file descriptor passing.
1774		2268
1775	AUTHOR	2269	AUTHOR
1776	Marc Lehmann <schmorp@schmorp.de>	2270	Marc Lehmann <schmorp@schmorp.de>
1777	http://home.schmorp.de/	2271	http://home.schmorp.de/
1778		2272

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Revision 1.71 by root, Fri Feb 16 21:20:52 2024 UTC