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Revision 1.216 by root, Sun Oct 9 08:24:49 2011 UTC vs.
Revision 1.309 by root, Tue Dec 29 15:20:12 2020 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	IO::AIO - Asynchronous Input/Output	3	IO::AIO - Asynchronous/Advanced Input/Output
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
…		…
58	not well-supported or restricted (GNU/Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
59	files currently, for example), and they would only support aio_read and	59	files currently, for example), and they would only support aio_read and
60	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
61	using threads anyway.	61	using threads anyway.
62		62
		63	In addition to asynchronous I/O, this module also exports some rather
		64	arcane interfaces, such as C<madvise> or linux's C<splice> system call,
		65	which is why the C<A> in C<AIO> can also mean I<advanced>.
		66
63	Although the module will work in the presence of other (Perl-) threads,	67	Although the module will work in the presence of other (Perl-) threads,
64	it is currently not reentrant in any way, so use appropriate locking	68	it is currently not reentrant in any way, so use appropriate locking
65	yourself, always call C<poll_cb> from within the same thread, or never	69	yourself, always call C<poll_cb> from within the same thread, or never
66	call C<poll_cb> (or other C<aio_> functions) recursively.	70	call C<poll_cb> (or other C<aio_> functions) recursively.
67		71
68	=head2 EXAMPLE	72	=head2 EXAMPLE
69		73
70	This is a simple example that uses the EV module and loads	74	This is a simple example that uses the EV module and loads
71	F</etc/passwd> asynchronously:	75	F</etc/passwd> asynchronously:
72		76
73	use Fcntl;
74	use EV;	77	use EV;
75	use IO::AIO;	78	use IO::AIO;
76		79
77	# register the IO::AIO callback with EV	80	# register the IO::AIO callback with EV
78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	81	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
…		…
95		98
96	# file contents now in $contents	99	# file contents now in $contents
97	print $contents;	100	print $contents;
98		101
99	# exit event loop and program	102	# exit event loop and program
100	EV::unloop;	103	EV::break;
101	};	104	};
102	};	105	};
103		106
104	# possibly queue up other requests, or open GUI windows,	107	# possibly queue up other requests, or open GUI windows,
105	# check for sockets etc. etc.	108	# check for sockets etc. etc.
106		109
107	# process events as long as there are some:	110	# process events as long as there are some:
108	EV::loop;	111	EV::run;
109		112
110	=head1 REQUEST ANATOMY AND LIFETIME	113	=head1 REQUEST ANATOMY AND LIFETIME
111		114
112	Every C<aio_*> function creates a request. which is a C data structure not	115	Every C<aio_*> function creates a request. which is a C data structure not
113	directly visible to Perl.	116	directly visible to Perl.
…		…
168	use common::sense;	171	use common::sense;
169		172
170	use base 'Exporter';	173	use base 'Exporter';
171		174
172	BEGIN {	175	BEGIN {
173	our $VERSION = '4.1';	176	our $VERSION = 4.74;
174		177
175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	178	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx	179	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate	181	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
179	aio_pathsync aio_readahead	182	aio_pathsync aio_readahead aio_fiemap aio_allocate
180	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
181	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	184	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
182	aio_chmod aio_utime aio_truncate	185	aio_chmod aio_utime aio_truncate
183	aio_msync aio_mtouch aio_mlock aio_mlockall	186	aio_msync aio_mtouch aio_mlock aio_mlockall
184	aio_statvfs	187	aio_statvfs
		188	aio_slurp
185	aio_wd);	189	aio_wd);
186		190
187	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	191	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
188	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	192	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
189	min_parallel max_parallel max_idle idle_timeout	193	min_parallel max_parallel max_idle idle_timeout
190	nreqs nready npending nthreads	194	nreqs nready npending nthreads
191	max_poll_time max_poll_reqs	195	max_poll_time max_poll_reqs
192	sendfile fadvise madvise	196	sendfile fadvise madvise
193	mmap munmap munlock munlockall);	197	mmap munmap mremap munlock munlockall);
194		198
195	push @AIO_REQ, qw(aio_busy); # not exported	199	push @AIO_REQ, qw(aio_busy); # not exported
196		200
197	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	201	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
198		202
…		…
202		206
203	=head1 FUNCTIONS	207	=head1 FUNCTIONS
204		208
205	=head2 QUICK OVERVIEW	209	=head2 QUICK OVERVIEW
206		210
207	This section simply lists the prototypes of the most important functions	211	This section simply lists the prototypes most of the functions for
208	for quick reference. See the following sections for function-by-function	212	quick reference. See the following sections for function-by-function
209	documentation.	213	documentation.
210		214
211	aio_wd $pathname, $callback->($wd)	215	aio_wd $pathname, $callback->($wd)
212	aio_open $pathname, $flags, $mode, $callback->($fh)	216	aio_open $pathname, $flags, $mode, $callback->($fh)
213	aio_close $fh, $callback->($status)	217	aio_close $fh, $callback->($status)
		218	aio_seek $fh,$offset,$whence, $callback->($offs)
214	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	219	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
215	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	220	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
216	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	221	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
217	aio_readahead $fh,$offset,$length, $callback->($retval)	222	aio_readahead $fh,$offset,$length, $callback->($retval)
218	aio_stat $fh_or_path, $callback->($status)	223	aio_stat $fh_or_path, $callback->($status)
219	aio_lstat $fh, $callback->($status)	224	aio_lstat $fh, $callback->($status)
220	aio_statvfs $fh_or_path, $callback->($statvfs)	225	aio_statvfs $fh_or_path, $callback->($statvfs)
221	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	226	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
222	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	227	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		228	aio_chmod $fh_or_path, $mode, $callback->($status)
223	aio_truncate $fh_or_path, $offset, $callback->($status)	229	aio_truncate $fh_or_path, $offset, $callback->($status)
224	aio_chmod $fh_or_path, $mode, $callback->($status)	230	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		231	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
225	aio_unlink $pathname, $callback->($status)	232	aio_unlink $pathname, $callback->($status)
226	aio_mknod $pathname, $mode, $dev, $callback->($status)	233	aio_mknod $pathname, $mode, $dev, $callback->($status)
227	aio_link $srcpath, $dstpath, $callback->($status)	234	aio_link $srcpath, $dstpath, $callback->($status)
228	aio_symlink $srcpath, $dstpath, $callback->($status)	235	aio_symlink $srcpath, $dstpath, $callback->($status)
229	aio_readlink $pathname, $callback->($link)	236	aio_readlink $pathname, $callback->($link)
230	aio_realpath $pathname, $callback->($link)	237	aio_realpath $pathname, $callback->($path)
231	aio_rename $srcpath, $dstpath, $callback->($status)	238	aio_rename $srcpath, $dstpath, $callback->($status)
		239	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
232	aio_mkdir $pathname, $mode, $callback->($status)	240	aio_mkdir $pathname, $mode, $callback->($status)
233	aio_rmdir $pathname, $callback->($status)	241	aio_rmdir $pathname, $callback->($status)
234	aio_readdir $pathname, $callback->($entries)	242	aio_readdir $pathname, $callback->($entries)
235	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	243	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
236	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	244	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
…		…
238	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)	246	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
239	aio_load $pathname, $data, $callback->($status)	247	aio_load $pathname, $data, $callback->($status)
240	aio_copy $srcpath, $dstpath, $callback->($status)	248	aio_copy $srcpath, $dstpath, $callback->($status)
241	aio_move $srcpath, $dstpath, $callback->($status)	249	aio_move $srcpath, $dstpath, $callback->($status)
242	aio_rmtree $pathname, $callback->($status)	250	aio_rmtree $pathname, $callback->($status)
		251	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		252	aio_ioctl $fh, $request, $buf, $callback->($status)
243	aio_sync $callback->($status)	253	aio_sync $callback->($status)
244	aio_syncfs $fh, $callback->($status)	254	aio_syncfs $fh, $callback->($status)
245	aio_fsync $fh, $callback->($status)	255	aio_fsync $fh, $callback->($status)
246	aio_fdatasync $fh, $callback->($status)	256	aio_fdatasync $fh, $callback->($status)
247	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	257	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
248	aio_pathsync $pathname, $callback->($status)	258	aio_pathsync $pathname, $callback->($status)
249	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	259	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
250	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	260	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
251	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	261	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
252	aio_mlockall $flags, $callback->($status)	262	aio_mlockall $flags, $callback->($status)
253	aio_group $callback->(...)	263	aio_group $callback->(...)
254	aio_nop $callback->()	264	aio_nop $callback->()
…		…
268	IO::AIO::idle_timeout $seconds	278	IO::AIO::idle_timeout $seconds
269	IO::AIO::max_outstanding $maxreqs	279	IO::AIO::max_outstanding $maxreqs
270	IO::AIO::nreqs	280	IO::AIO::nreqs
271	IO::AIO::nready	281	IO::AIO::nready
272	IO::AIO::npending	282	IO::AIO::npending
		283	IO::AIO::reinit
		284
		285	$nfd = IO::AIO::get_fdlimit
		286	IO::AIO::min_fdlimit $nfd
273		287
274	IO::AIO::sendfile $ofh, $ifh, $offset, $count	288	IO::AIO::sendfile $ofh, $ifh, $offset, $count
275	IO::AIO::fadvise $fh, $offset, $len, $advice	289	IO::AIO::fadvise $fh, $offset, $len, $advice
		290
		291	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		292	IO::AIO::munmap $scalar
		293	IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
276	IO::AIO::madvise $scalar, $offset, $length, $advice	294	IO::AIO::madvise $scalar, $offset, $length, $advice
277	IO::AIO::mprotect $scalar, $offset, $length, $protect	295	IO::AIO::mprotect $scalar, $offset, $length, $protect
278	IO::AIO::munlock $scalar, $offset = 0, $length = undef	296	IO::AIO::munlock $scalar, $offset = 0, $length = undef
279	IO::AIO::munlockall	297	IO::AIO::munlockall
280		298
281	=head2 AIO REQUEST FUNCTIONS	299	# stat extensions
		300	$counter = IO::AIO::st_gen
		301	$seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		302	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		303	$nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		304	$seconds = IO::AIO::st_btimesec
		305	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		306
		307	# very much unportable syscalls
		308	IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
		309	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		310	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		311	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		312	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		313	$fh = IO::AIO::memfd_create $pathname[, $flags]
		314	$fh = IO::AIO::eventfd [$initval, [$flags]]
		315	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		316	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		317	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		318
		319	=head2 API NOTES
282		320
283	All the C<aio_*> calls are more or less thin wrappers around the syscall	321	All the C<aio_*> calls are more or less thin wrappers around the syscall
284	with the same name (sans C<aio_>). The arguments are similar or identical,	322	with the same name (sans C<aio_>). The arguments are similar or identical,
285	and they all accept an additional (and optional) C<$callback> argument	323	and they all accept an additional (and optional) C<$callback> argument
286	which must be a code reference. This code reference will be called after	324	which must be a code reference. This code reference will be called after
…		…
317	correct contents.	355	correct contents.
318		356
319	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	357	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
320	handles correctly whether it is set or not.	358	handles correctly whether it is set or not.
321		359
		360	=head2 AIO REQUEST FUNCTIONS
		361
322	=over 4	362	=over 4
323		363
324	=item $prev_pri = aioreq_pri [$pri]	364	=item $prev_pri = aioreq_pri [$pri]
325		365
326	Returns the priority value that would be used for the next request and, if	366	Returns the priority value that would be used for the next request and, if
…		…
355		395
356		396
357	=item aio_open $pathname, $flags, $mode, $callback->($fh)	397	=item aio_open $pathname, $flags, $mode, $callback->($fh)
358		398
359	Asynchronously open or create a file and call the callback with a newly	399	Asynchronously open or create a file and call the callback with a newly
360	created filehandle for the file.	400	created filehandle for the file (or C<undef> in case of an error).
361		401
362	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	402	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
363	for an explanation.	403	for an explanation.
364		404
365	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	405	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
388	following POSIX and non-POSIX constants are available (missing ones on	428	following POSIX and non-POSIX constants are available (missing ones on
389	your system are, as usual, C<0>):	429	your system are, as usual, C<0>):
390		430
391	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,	431	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
392	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,	432	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
393	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.	433	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
394		434
395		435
396	=item aio_close $fh, $callback->($status)	436	=item aio_close $fh, $callback->($status)
397		437
398	Asynchronously close a file and call the callback with the result	438	Asynchronously close a file and call the callback with the result
…		…
408	Or in other words: the file descriptor will be closed, but it will not be	448	Or in other words: the file descriptor will be closed, but it will not be
409	free for reuse until the perl filehandle is closed.	449	free for reuse until the perl filehandle is closed.
410		450
411	=cut	451	=cut
412		452
		453	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		454
		455	Seeks the filehandle to the new C<$offset>, similarly to perl's
		456	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		457	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		458	C<IO::AIO::SEEK_END>).
		459
		460	The resulting absolute offset will be passed to the callback, or C<-1> in
		461	case of an error.
		462
		463	In theory, the C<$whence> constants could be different than the
		464	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		465	so don't panic.
		466
		467	As a GNU/Linux (and maybe Solaris) extension, also the constants
		468	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		469	could be found. No guarantees about suitability for use in C<aio_seek> or
		470	Perl's C<sysseek> can be made though, although I would naively assume they
		471	"just work".
		472
413	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	473	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
414		474
415	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	475	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
416		476
417	Reads or writes C<$length> bytes from or to the specified C<$fh> and	477	Reads or writes C<$length> bytes from or to the specified C<$fh> and
418	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	478	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
419	and calls the callback without the actual number of bytes read (or -1 on	479	calls the callback with the actual number of bytes transferred (or -1 on
420	error, just like the syscall).	480	error, just like the syscall).
421		481
422	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	482	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
423	offset plus the actual number of bytes read.	483	offset plus the actual number of bytes read.
424		484
…		…
482	As native sendfile syscalls (as practically any non-POSIX interface hacked	542	As native sendfile syscalls (as practically any non-POSIX interface hacked
483	together in a hurry to improve benchmark numbers) tend to be rather buggy	543	together in a hurry to improve benchmark numbers) tend to be rather buggy
484	on many systems, this implementation tries to work around some known bugs	544	on many systems, this implementation tries to work around some known bugs
485	in Linux and FreeBSD kernels (probably others, too), but that might fail,	545	in Linux and FreeBSD kernels (probably others, too), but that might fail,
486	so you really really should check the return value of C<aio_sendfile> -	546	so you really really should check the return value of C<aio_sendfile> -
487	fewre bytes than expected might have been transferred.	547	fewer bytes than expected might have been transferred.
488		548
489		549
490	=item aio_readahead $fh,$offset,$length, $callback->($retval)	550	=item aio_readahead $fh,$offset,$length, $callback->($retval)
491		551
492	C<aio_readahead> populates the page cache with data from a file so that	552	C<aio_readahead> populates the page cache with data from a file so that
…		…
496	whole pages, so that offset is effectively rounded down to a page boundary	556	whole pages, so that offset is effectively rounded down to a page boundary
497	and bytes are read up to the next page boundary greater than or equal to	557	and bytes are read up to the next page boundary greater than or equal to
498	(off-set+length). C<aio_readahead> does not read beyond the end of the	558	(off-set+length). C<aio_readahead> does not read beyond the end of the
499	file. The current file offset of the file is left unchanged.	559	file. The current file offset of the file is left unchanged.
500		560
501	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	561	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
502	emulated by simply reading the data, which would have a similar effect.	562	be emulated by simply reading the data, which would have a similar effect.
503		563
504		564
505	=item aio_stat $fh_or_path, $callback->($status)	565	=item aio_stat $fh_or_path, $callback->($status)
506		566
507	=item aio_lstat $fh, $callback->($status)	567	=item aio_lstat $fh, $callback->($status)
508		568
509	Works like perl's C<stat> or C<lstat> in void context. The callback will	569	Works almost exactly like perl's C<stat> or C<lstat> in void context. The
510	be called after the stat and the results will be available using C<stat _>	570	callback will be called after the stat and the results will be available
511	or C<-s _> etc...	571	using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
		572	and C<-T>).
512		573
513	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,	574	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
514	for an explanation.	575	for an explanation.
515		576
516	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	577	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
…		…
523	behaviour).	584	behaviour).
524		585
525	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,	586	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
526	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,	587	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
527	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.	588	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		589
		590	To access higher resolution stat timestamps, see L<SUBSECOND STAT TIME
		591	ACCESS>.
528		592
529	Example: Print the length of F</etc/passwd>:	593	Example: Print the length of F</etc/passwd>:
530		594
531	aio_stat "/etc/passwd", sub {	595	aio_stat "/etc/passwd", sub {
532	$_[0] and die "stat failed: $!";	596	$_[0] and die "stat failed: $!";
…		…
576	namemax => 255,	640	namemax => 255,
577	frsize => 1024,	641	frsize => 1024,
578	fsid => 1810	642	fsid => 1810
579	}	643	}
580		644
581
582	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	645	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
583		646
584	Works like perl's C<utime> function (including the special case of $atime	647	Works like perl's C<utime> function (including the special case of $atime
585	and $mtime being undef). Fractional times are supported if the underlying	648	and $mtime being undef). Fractional times are supported if the underlying
586	syscalls support them.	649	syscalls support them.
587		650
588	When called with a pathname, uses utimes(2) if available, otherwise	651	When called with a pathname, uses utimensat(2) or utimes(2) if available,
589	utime(2). If called on a file descriptor, uses futimes(2) if available,	652	otherwise utime(2). If called on a file descriptor, uses futimens(2)
590	otherwise returns ENOSYS, so this is not portable.	653	or futimes(2) if available, otherwise returns ENOSYS, so this is not
		654	portable.
591		655
592	Examples:	656	Examples:
593		657
594	# set atime and mtime to current time (basically touch(1)):	658	# set atime and mtime to current time (basically touch(1)):
595	aio_utime "path", undef, undef;	659	aio_utime "path", undef, undef;
…		…
613	=item aio_truncate $fh_or_path, $offset, $callback->($status)	677	=item aio_truncate $fh_or_path, $offset, $callback->($status)
614		678
615	Works like truncate(2) or ftruncate(2).	679	Works like truncate(2) or ftruncate(2).
616		680
617		681
		682	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		683
		684	Allocates or frees disk space according to the C<$mode> argument. See the
		685	linux C<fallocate> documentation for details.
		686
		687	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		688	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		689	to deallocate a file range.
		690
		691	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		692	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		693	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		694	to unshare shared blocks (see your L<fallocate(2)> manpage).
		695
		696	The file system block size used by C<fallocate> is presumably the
		697	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		698	can dictate other limitations.
		699
		700	If C<fallocate> isn't available or cannot be emulated (currently no
		701	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		702
		703
618	=item aio_chmod $fh_or_path, $mode, $callback->($status)	704	=item aio_chmod $fh_or_path, $mode, $callback->($status)
619		705
620	Works like perl's C<chmod> function.	706	Works like perl's C<chmod> function.
621		707
622		708
…		…
659		745
660		746
661	=item aio_realpath $pathname, $callback->($path)	747	=item aio_realpath $pathname, $callback->($path)
662		748
663	Asynchronously make the path absolute and resolve any symlinks in	749	Asynchronously make the path absolute and resolve any symlinks in
664	C<$path>. The resulting path only consists of directories (Same as	750	C<$path>. The resulting path only consists of directories (same as
665	L<Cwd::realpath>).	751	L<Cwd::realpath>).
666		752
667	This request can be used to get the absolute path of the current working	753	This request can be used to get the absolute path of the current working
668	directory by passing it a path of F<.> (a single dot).	754	directory by passing it a path of F<.> (a single dot).
669		755
670		756
671	=item aio_rename $srcpath, $dstpath, $callback->($status)	757	=item aio_rename $srcpath, $dstpath, $callback->($status)
672		758
673	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	759	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
674	rename(2) and call the callback with the result code.	760	rename(2) and call the callback with the result code.
		761
		762	On systems that support the AIO::WD working directory abstraction
		763	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		764	of failing, C<rename> is called on the absolute path of C<$wd>.
		765
		766
		767	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		768
		769	Basically a version of C<aio_rename> with an additional C<$flags>
		770	argument. Calling this with C<$flags=0> is the same as calling
		771	C<aio_rename>.
		772
		773	Non-zero flags are currently only supported on GNU/Linux systems that
		774	support renameat2. Other systems fail with C<ENOSYS> in this case.
		775
		776	The following constants are available (missing ones are, as usual C<0>),
		777	see renameat2(2) for details:
		778
		779	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		780	and C<IO::AIO::RENAME_WHITEOUT>.
675		781
676		782
677	=item aio_mkdir $pathname, $mode, $callback->($status)	783	=item aio_mkdir $pathname, $mode, $callback->($status)
678		784
679	Asynchronously mkdir (create) a directory and call the callback with	785	Asynchronously mkdir (create) a directory and call the callback with
…		…
684	=item aio_rmdir $pathname, $callback->($status)	790	=item aio_rmdir $pathname, $callback->($status)
685		791
686	Asynchronously rmdir (delete) a directory and call the callback with the	792	Asynchronously rmdir (delete) a directory and call the callback with the
687	result code.	793	result code.
688		794
		795	On systems that support the AIO::WD working directory abstraction
		796	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		797	C<rmdir> is called on the absolute path of C<$wd>.
		798
689		799
690	=item aio_readdir $pathname, $callback->($entries)	800	=item aio_readdir $pathname, $callback->($entries)
691		801
692	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	802	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
693	directory (i.e. opendir + readdir + closedir). The entries will not be	803	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
708		818
709	=over 4	819	=over 4
710		820
711	=item IO::AIO::READDIR_DENTS	821	=item IO::AIO::READDIR_DENTS
712		822
713	When this flag is off, then the callback gets an arrayref consisting of	823	Normally the callback gets an arrayref consisting of names only (as
714	names only (as with C<aio_readdir>), otherwise it gets an arrayref with	824	with C<aio_readdir>). If this flag is set, then the callback gets an
715	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	825	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
716	entry in more detail.	826	single directory entry in more detail:
717		827
718	C<$name> is the name of the entry.	828	C<$name> is the name of the entry.
719		829
720	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	830	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
721		831
722	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	832	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
723	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	833	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
724	C<IO::AIO::DT_WHT>.	834	C<IO::AIO::DT_WHT>.
725		835
726	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	836	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
727	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	837	to know, you have to run stat yourself. Also, for speed/memory reasons,
728	scalars are read-only: you can not modify them.	838	the C<$type> scalars are read-only: you must not modify them.
729		839
730	C<$inode> is the inode number (which might not be exact on systems with 64	840	C<$inode> is the inode number (which might not be exact on systems with 64
731	bit inode numbers and 32 bit perls). This field has unspecified content on	841	bit inode numbers and 32 bit perls). This field has unspecified content on
732	systems that do not deliver the inode information.	842	systems that do not deliver the inode information.
733		843
…		…
744	short names are tried first.	854	short names are tried first.
745		855
746	=item IO::AIO::READDIR_STAT_ORDER	856	=item IO::AIO::READDIR_STAT_ORDER
747		857
748	When this flag is set, then the names will be returned in an order	858	When this flag is set, then the names will be returned in an order
749	suitable for stat()'ing each one. That is, when you plan to stat()	859	suitable for stat()'ing each one. That is, when you plan to stat() most or
750	all files in the given directory, then the returned order will likely	860	all files in the given directory, then the returned order will likely be
751	be fastest.	861	faster.
752		862
753	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then	863	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
754	the likely dirs come first, resulting in a less optimal stat order.	864	then the likely dirs come first, resulting in a less optimal stat order
		865	for stat'ing all entries, but likely a more optimal order for finding
		866	subdirectories.
755		867
756	=item IO::AIO::READDIR_FOUND_UNKNOWN	868	=item IO::AIO::READDIR_FOUND_UNKNOWN
757		869
758	This flag should not be set when calling C<aio_readdirx>. Instead, it	870	This flag should not be set when calling C<aio_readdirx>. Instead, it
759	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	871	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
…		…
761	C<$type>'s are known, which can be used to speed up some algorithms.	873	C<$type>'s are known, which can be used to speed up some algorithms.
762		874
763	=back	875	=back
764		876
765		877
		878	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		879
		880	Opens, reads and closes the given file. The data is put into C<$data>,
		881	which is resized as required.
		882
		883	If C<$offset> is negative, then it is counted from the end of the file.
		884
		885	If C<$length> is zero, then the remaining length of the file is
		886	used. Also, in this case, the same limitations to modifying C<$data> apply
		887	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		888	with C<substr>. If the size of the file is known, specifying a non-zero
		889	C<$length> results in a performance advantage.
		890
		891	This request is similar to the older C<aio_load> request, but since it is
		892	a single request, it might be more efficient to use.
		893
		894	Example: load F</etc/passwd> into C<$passwd>.
		895
		896	my $passwd;
		897	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		898	$_[0] >= 0
		899	or die "/etc/passwd: $!\n";
		900
		901	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		902	print $passwd;
		903	};
		904	IO::AIO::flush;
		905
		906
766	=item aio_load $pathname, $data, $callback->($status)	907	=item aio_load $pathname, $data, $callback->($status)
767		908
768	This is a composite request that tries to fully load the given file into	909	This is a composite request that tries to fully load the given file into
769	memory. Status is the same as with aio_read.	910	memory. Status is the same as with aio_read.
		911
		912	Using C<aio_slurp> might be more efficient, as it is a single request.
770		913
771	=cut	914	=cut
772		915
773	sub aio_load($$;$) {	916	sub aio_load($$;$) {
774	my ($path, undef, $cb) = @_;	917	my ($path, undef, $cb) = @_;
…		…
794	=item aio_copy $srcpath, $dstpath, $callback->($status)	937	=item aio_copy $srcpath, $dstpath, $callback->($status)
795		938
796	Try to copy the I<file> (directories not supported as either source or	939	Try to copy the I<file> (directories not supported as either source or
797	destination) from C<$srcpath> to C<$dstpath> and call the callback with	940	destination) from C<$srcpath> to C<$dstpath> and call the callback with
798	a status of C<0> (ok) or C<-1> (error, see C<$!>).	941	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		942
		943	Existing destination files will be truncated.
799		944
800	This is a composite request that creates the destination file with	945	This is a composite request that creates the destination file with
801	mode 0200 and copies the contents of the source file into it using	946	mode 0200 and copies the contents of the source file into it using
802	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	947	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
803	uid/gid, in that order.	948	uid/gid, in that order.
…		…
913	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1058	Scans a directory (similar to C<aio_readdir>) but additionally tries to
914	efficiently separate the entries of directory C<$path> into two sets of	1059	efficiently separate the entries of directory C<$path> into two sets of
915	names, directories you can recurse into (directories), and ones you cannot	1060	names, directories you can recurse into (directories), and ones you cannot
916	recurse into (everything else, including symlinks to directories).	1061	recurse into (everything else, including symlinks to directories).
917		1062
918	C<aio_scandir> is a composite request that creates of many sub requests_	1063	C<aio_scandir> is a composite request that generates many sub requests.
919	C<$maxreq> specifies the maximum number of outstanding aio requests that	1064	C<$maxreq> specifies the maximum number of outstanding aio requests that
920	this function generates. If it is C<< <= 0 >>, then a suitable default	1065	this function generates. If it is C<< <= 0 >>, then a suitable default
921	will be chosen (currently 4).	1066	will be chosen (currently 4).
922		1067
923	On error, the callback is called without arguments, otherwise it receives	1068	On error, the callback is called without arguments, otherwise it receives
…		…
987	aioreq_pri $pri;	1132	aioreq_pri $pri;
988	add $grp aio_stat $wd, sub {	1133	add $grp aio_stat $wd, sub {
989	return $grp->result () if $_[0];	1134	return $grp->result () if $_[0];
990	my $now = time;	1135	my $now = time;
991	my $hash1 = join ":", (stat _)[0,1,3,7,9];	1136	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		1137	my $rdxflags = READDIR_DIRS_FIRST;
		1138
		1139	if ((stat _)[3] < 2) {
		1140	# at least one non-POSIX filesystem exists
		1141	# that returns useful DT_type values: btrfs,
		1142	# so optimise for this here by requesting dents
		1143	$rdxflags |= READDIR_DENTS;
		1144	}
992		1145
993	# read the directory entries	1146	# read the directory entries
994	aioreq_pri $pri;	1147	aioreq_pri $pri;
995	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {	1148	add $grp aio_readdirx $wd, $rdxflags, sub {
996	my $entries = shift	1149	my ($entries, $flags) = @_
997	or return $grp->result ();	1150	or return $grp->result ();
		1151
		1152	if ($rdxflags & READDIR_DENTS) {
		1153	# if we requested type values, see if we can use them directly.
		1154
		1155	# if there were any DT_UNKNOWN entries then we assume we
		1156	# don't know. alternatively, we could assume that if we get
		1157	# one DT_DIR, then all directories are indeed marked with
		1158	# DT_DIR, but this seems not required for btrfs, and this
		1159	# is basically the "btrfs can't get it's act together" code
		1160	# branch.
		1161	unless ($flags & READDIR_FOUND_UNKNOWN) {
		1162	# now we have valid DT_ information for all entries,
		1163	# so use it as an optimisation without further stat's.
		1164	# they must also all be at the beginning of @$entries
		1165	# by now.
		1166
		1167	my $dirs;
		1168
		1169	if (@$entries) {
		1170	for (0 .. $#$entries) {
		1171	if ($entries->[$_][1] != DT_DIR) {
		1172	# splice out directories
		1173	$dirs = [splice @$entries, 0, $_];
		1174	last;
		1175	}
		1176	}
		1177
		1178	# if we didn't find any non-dir, then all entries are dirs
		1179	unless ($dirs) {
		1180	($dirs, $entries) = ($entries, []);
		1181	}
		1182	} else {
		1183	# directory is empty, so there are no sbdirs
		1184	$dirs = [];
		1185	}
		1186
		1187	# either splice'd the directories out or the dir was empty.
		1188	# convert dents to filenames
		1189	$_ = $_->[0] for @$dirs;
		1190	$_ = $_->[0] for @$entries;
		1191
		1192	return $grp->result ($dirs, $entries);
		1193	}
		1194
		1195	# cannot use, so return to our old ways
		1196	# by pretending we only scanned for names.
		1197	$_ = $_->[0] for @$entries;
		1198	}
998		1199
999	# stat the dir another time	1200	# stat the dir another time
1000	aioreq_pri $pri;	1201	aioreq_pri $pri;
1001	add $grp aio_stat $wd, sub {	1202	add $grp aio_stat $wd, sub {
1002	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1203	my $hash2 = join ":", (stat _)[0,1,3,7,9];
…		…
1057	}	1258	}
1058		1259
1059	=item aio_rmtree $pathname, $callback->($status)	1260	=item aio_rmtree $pathname, $callback->($status)
1060		1261
1061	Delete a directory tree starting (and including) C<$path>, return the	1262	Delete a directory tree starting (and including) C<$path>, return the
1062	status of the final C<rmdir> only. This is a composite request that	1263	status of the final C<rmdir> only. This is a composite request that
1063	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1264	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1064	everything else.	1265	everything else.
1065		1266
1066	=cut	1267	=cut
1067		1268
…		…
1088	add $grp $dirgrp;	1289	add $grp $dirgrp;
1089	};	1290	};
1090		1291
1091	$grp	1292	$grp
1092	}	1293	}
		1294
		1295	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1296
		1297	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1298
		1299	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1300	they execute asynchronously and pass the return value to the callback.
		1301
		1302	Both calls can be used for a lot of things, some of which make more sense
		1303	to run asynchronously in their own thread, while some others make less
		1304	sense. For example, calls that block waiting for external events, such
		1305	as locking, will also lock down an I/O thread while it is waiting, which
		1306	can deadlock the whole I/O system. At the same time, there might be no
		1307	alternative to using a thread to wait.
		1308
		1309	So in general, you should only use these calls for things that do
		1310	(filesystem) I/O, not for things that wait for other events (network,
		1311	other processes), although if you are careful and know what you are doing,
		1312	you still can.
		1313
		1314	The following constants are available and can be used for normal C<ioctl>
		1315	and C<fcntl> as well (missing ones are, as usual C<0>):
		1316
		1317	C<F_DUPFD_CLOEXEC>,
		1318
		1319	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1320
		1321	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1322
		1323	C<F_ADD_SEALS>, C<F_GET_SEALS>, C<F_SEAL_SEAL>, C<F_SEAL_SHRINK>, C<F_SEAL_GROW> and
		1324	C<F_SEAL_WRITE>.
		1325
		1326	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1327	C<FS_IOC_FIEMAP>.
		1328
		1329	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1330	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1331
		1332	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1333	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1334	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1335	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1336	C<FS_FL_USER_MODIFIABLE>.
		1337
		1338	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1339	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1340	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1341	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
1093		1342
1094	=item aio_sync $callback->($status)	1343	=item aio_sync $callback->($status)
1095		1344
1096	Asynchronously call sync and call the callback when finished.	1345	Asynchronously call sync and call the callback when finished.
1097		1346
…		…
1166	};	1415	};
1167		1416
1168	$grp	1417	$grp
1169	}	1418	}
1170		1419
1171	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1420	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1172		1421
1173	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1422	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1174	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1423	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1175	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1424	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1176	scalar must only be modified in-place while an aio operation is pending on	1425	scalar must only be modified in-place while an aio operation is pending on
…		…
1178		1427
1179	It calls the C<msync> function of your OS, if available, with the memory	1428	It calls the C<msync> function of your OS, if available, with the memory
1180	area starting at C<$offset> in the string and ending C<$length> bytes	1429	area starting at C<$offset> in the string and ending C<$length> bytes
1181	later. If C<$length> is negative, counts from the end, and if C<$length>	1430	later. If C<$length> is negative, counts from the end, and if C<$length>
1182	is C<undef>, then it goes till the end of the string. The flags can be	1431	is C<undef>, then it goes till the end of the string. The flags can be
1183	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1432	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1184	C<IO::AIO::MS_SYNC>.	1433	C<IO::AIO::MS_INVALIDATE>.
1185		1434
1186	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1435	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1187		1436
1188	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1437	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1189	scalars.	1438	scalars.
1190		1439
1191	It touches (reads or writes) all memory pages in the specified	1440	It touches (reads or writes) all memory pages in the specified
1192	range inside the scalar. All caveats and parameters are the same	1441	range inside the scalar. All caveats and parameters are the same
1193	as for C<aio_msync>, above, except for flags, which must be either	1442	as for C<aio_msync>, above, except for flags, which must be either
1194	C<0> (which reads all pages and ensures they are instantiated) or	1443	C<0> (which reads all pages and ensures they are instantiated) or
1195	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1444	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1196	writing an octet from it, which dirties the page).	1445	writing an octet from it, which dirties the page).
1197		1446
1198	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1447	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1199		1448
1200	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1449	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1219	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;	1468	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1220	aio_mlock $data; # mlock in background	1469	aio_mlock $data; # mlock in background
1221		1470
1222	=item aio_mlockall $flags, $callback->($status)	1471	=item aio_mlockall $flags, $callback->($status)
1223		1472
1224	Calls the C<mlockall> function with the given C<$flags> (a combination of	1473	Calls the C<mlockall> function with the given C<$flags> (a
1225	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).	1474	combination of C<IO::AIO::MCL_CURRENT>, C<IO::AIO::MCL_FUTURE> and
		1475	C<IO::AIO::MCL_ONFAULT>).
1226		1476
1227	On systems that do not implement C<mlockall>, this function returns C<-1>	1477	On systems that do not implement C<mlockall>, this function returns C<-1>
1228	and sets errno to C<ENOSYS>.	1478	and sets errno to C<ENOSYS>. Similarly, flag combinations not supported
		1479	by the system result in a return value of C<-1> with errno being set to
		1480	C<EINVAL>.
1229		1481
1230	Note that the corresponding C<munlockall> is synchronous and is	1482	Note that the corresponding C<munlockall> is synchronous and is
1231	documented under L<MISCELLANEOUS FUNCTIONS>.	1483	documented under L<MISCELLANEOUS FUNCTIONS>.
1232		1484
1233	Example: asynchronously lock all current and future pages into memory.	1485	Example: asynchronously lock all current and future pages into memory.
1234		1486
1235	aio_mlockall IO::AIO::MCL_FUTURE;	1487	aio_mlockall IO::AIO::MCL_FUTURE;
		1488
		1489	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1490
		1491	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1492	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1493	the ioctl is not available on your OS, then this request will fail with
		1494	C<ENOSYS>.
		1495
		1496	C<$start> is the starting offset to query extents for, C<$length> is the
		1497	size of the range to query - if it is C<undef>, then the whole file will
		1498	be queried.
		1499
		1500	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1501	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1502	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1503	the data portion.
		1504
		1505	C<$count> is the maximum number of extent records to return. If it is
		1506	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1507	case, if it is C<0>, then the callback receives the number of extents
		1508	instead of the extents themselves (which is unreliable, see below).
		1509
		1510	If an error occurs, the callback receives no arguments. The special
		1511	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1512
		1513	Otherwise, the callback receives an array reference with extent
		1514	structures. Each extent structure is an array reference itself, with the
		1515	following members:
		1516
		1517	[$logical, $physical, $length, $flags]
		1518
		1519	Flags is any combination of the following flag values (typically either C<0>
		1520	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1521
		1522	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1523	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1524	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1525	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1526	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1527	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1528
		1529	At the time of this writing (Linux 3.2), this request is unreliable unless
		1530	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1531	it to return all extents of a range for files with a large number of
		1532	extents. The code (only) works around all these issues if C<$count> is
		1533	C<undef>.
1236		1534
1237	=item aio_group $callback->(...)	1535	=item aio_group $callback->(...)
1238		1536
1239	This is a very special aio request: Instead of doing something, it is a	1537	This is a very special aio request: Instead of doing something, it is a
1240	container for other aio requests, which is useful if you want to bundle	1538	container for other aio requests, which is useful if you want to bundle
…		…
1324	aio_stat [$etcdir, "passwd"], sub {	1622	aio_stat [$etcdir, "passwd"], sub {
1325	# yay	1623	# yay
1326	};	1624	};
1327	};	1625	};
1328		1626
1329	That C<aio_wd> is a request and not a normal function shows that creating	1627	The fact that C<aio_wd> is a request and not a normal function shows that
1330	an IO::AIO::WD object is itself a potentially blocking operation, which is	1628	creating an IO::AIO::WD object is itself a potentially blocking operation,
1331	why it is done asynchronously.	1629	which is why it is done asynchronously.
1332		1630
1333	To stat the directory obtained with C<aio_wd> above, one could write	1631	To stat the directory obtained with C<aio_wd> above, one could write
1334	either of the following three request calls:	1632	either of the following three request calls:
1335		1633
1336	aio_lstat "/etc" , sub { ... # pathname as normal string	1634	aio_lstat "/etc" , sub { ... # pathname as normal string
…		…
1353	There are some caveats: when directories get renamed (or deleted), the	1651	There are some caveats: when directories get renamed (or deleted), the
1354	pathname string doesn't change, so will point to the new directory (or	1652	pathname string doesn't change, so will point to the new directory (or
1355	nowhere at all), while the directory fd, if available on the system,	1653	nowhere at all), while the directory fd, if available on the system,
1356	will still point to the original directory. Most functions accepting a	1654	will still point to the original directory. Most functions accepting a
1357	pathname will use the directory fd on newer systems, and the string on	1655	pathname will use the directory fd on newer systems, and the string on
1358	older systems. Some functions (such as realpath) will always rely on the	1656	older systems. Some functions (such as C<aio_realpath>) will always rely on
1359	string form of the pathname.	1657	the string form of the pathname.
1360		1658
1361	So this fucntionality is mainly useful to get some protection against	1659	So this functionality is mainly useful to get some protection against
1362	C<chdir>, to easily get an absolute path out of a relative path for future	1660	C<chdir>, to easily get an absolute path out of a relative path for future
1363	reference, and to speed up doing many operations in the same directory	1661	reference, and to speed up doing many operations in the same directory
1364	(e.g. when stat'ing all files in a directory).	1662	(e.g. when stat'ing all files in a directory).
1365		1663
1366	The following functions implement this working directory abstraction:	1664	The following functions implement this working directory abstraction:
…		…
1379	passing C<undef> as working directory component of a pathname fails the	1677	passing C<undef> as working directory component of a pathname fails the
1380	request with C<ENOENT>, there is often no need for error checking in the	1678	request with C<ENOENT>, there is often no need for error checking in the
1381	C<aio_wd> callback, as future requests using the value will fail in the	1679	C<aio_wd> callback, as future requests using the value will fail in the
1382	expected way.	1680	expected way.
1383		1681
1384	If this call isn't available because your OS lacks it or it couldn't be
1385	detected, it will be emulated by calling C<fsync> instead.
1386
1387	=item IO::AIO::CWD	1682	=item IO::AIO::CWD
1388		1683
1389	This is a compiletime constant (object) that represents the process	1684	This is a compile time constant (object) that represents the process
1390	current working directory.	1685	current working directory.
1391		1686
1392	Specifying this object as working directory object for a pathname is as	1687	Specifying this object as working directory object for a pathname is as if
1393	if the pathname would be specified directly, without a directory object,	1688	the pathname would be specified directly, without a directory object. For
1394	e.g., these calls are functionally identical:	1689	example, these calls are functionally identical:
1395		1690
1396	aio_stat "somefile", sub { ... };	1691	aio_stat "somefile", sub { ... };
1397	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };	1692	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1398		1693
1399	=back	1694	=back
1400		1695
		1696	To recover the path associated with an IO::AIO::WD object, you can use
		1697	C<aio_realpath>:
		1698
		1699	aio_realpath $wd, sub {
		1700	warn "path is $_[0]\n";
		1701	};
		1702
		1703	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1704	sometimes, fall back to using an absolue path.
1401		1705
1402	=head2 IO::AIO::REQ CLASS	1706	=head2 IO::AIO::REQ CLASS
1403		1707
1404	All non-aggregate C<aio_*> functions return an object of this class when	1708	All non-aggregate C<aio_*> functions return an object of this class when
1405	called in non-void context.	1709	called in non-void context.
…		…
1566	The default value for the limit is C<0>, but note that setting a feeder	1870	The default value for the limit is C<0>, but note that setting a feeder
1567	automatically bumps it up to C<2>.	1871	automatically bumps it up to C<2>.
1568		1872
1569	=back	1873	=back
1570		1874
		1875
1571	=head2 SUPPORT FUNCTIONS	1876	=head2 SUPPORT FUNCTIONS
1572		1877
1573	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1878	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1574		1879
1575	=over 4	1880	=over 4
…		…
1583		1888
1584	See C<poll_cb> for an example.	1889	See C<poll_cb> for an example.
1585		1890
1586	=item IO::AIO::poll_cb	1891	=item IO::AIO::poll_cb
1587		1892
1588	Process some outstanding events on the result pipe. You have to call	1893	Process some requests that have reached the result phase (i.e. they have
		1894	been executed but the results are not yet reported). You have to call
		1895	this "regularly" to finish outstanding requests.
		1896
1589	this regularly. Returns C<0> if all events could be processed (or there	1897	Returns C<0> if all events could be processed (or there were no
1590	were no events to process), or C<-1> if it returned earlier for whatever	1898	events to process), or C<-1> if it returned earlier for whatever
1591	reason. Returns immediately when no events are outstanding. The amount of	1899	reason. Returns immediately when no events are outstanding. The amount
1592	events processed depends on the settings of C<IO::AIO::max_poll_req> and	1900	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1593	C<IO::AIO::max_poll_time>.	1901	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1594		1902
1595	If not all requests were processed for whatever reason, the filehandle	1903	If not all requests were processed for whatever reason, the poll file
1596	will still be ready when C<poll_cb> returns, so normally you don't have to	1904	descriptor will still be ready when C<poll_cb> returns, so normally you
1597	do anything special to have it called later.	1905	don't have to do anything special to have it called later.
1598		1906
1599	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1907	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1600	ready, it can be beneficial to call this function from loops which submit	1908	ready, it can be beneficial to call this function from loops which submit
1601	a lot of requests, to make sure the results get processed when they become	1909	a lot of requests, to make sure the results get processed when they become
1602	available and not just when the loop is finished and the event loop takes	1910	available and not just when the loop is finished and the event loop takes
…		…
1611	poll => 'r', async => 1,	1919	poll => 'r', async => 1,
1612	cb => \&IO::AIO::poll_cb);	1920	cb => \&IO::AIO::poll_cb);
1613		1921
1614	=item IO::AIO::poll_wait	1922	=item IO::AIO::poll_wait
1615		1923
1616	If there are any outstanding requests and none of them in the result	1924	Wait until either at least one request is in the result phase or no
1617	phase, wait till the result filehandle becomes ready for reading (simply	1925	requests are outstanding anymore.
1618	does a C<select> on the filehandle. This is useful if you want to	1926
1619	synchronously wait for some requests to finish).	1927	This is useful if you want to synchronously wait for some requests to
		1928	become ready, without actually handling them.
1620		1929
1621	See C<nreqs> for an example.	1930	See C<nreqs> for an example.
1622		1931
1623	=item IO::AIO::poll	1932	=item IO::AIO::poll
1624		1933
…		…
1635		1944
1636	Strictly equivalent to:	1945	Strictly equivalent to:
1637		1946
1638	IO::AIO::poll_wait, IO::AIO::poll_cb	1947	IO::AIO::poll_wait, IO::AIO::poll_cb
1639	while IO::AIO::nreqs;	1948	while IO::AIO::nreqs;
		1949
		1950	This function can be useful at program aborts, to make sure outstanding
		1951	I/O has been done (C<IO::AIO> uses an C<END> block which already calls
		1952	this function on normal exits), or when you are merely using C<IO::AIO>
		1953	for its more advanced functions, rather than for async I/O, e.g.:
		1954
		1955	my ($dirs, $nondirs);
		1956	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1957	IO::AIO::flush;
		1958	# $dirs, $nondirs are now set
1640		1959
1641	=item IO::AIO::max_poll_reqs $nreqs	1960	=item IO::AIO::max_poll_reqs $nreqs
1642		1961
1643	=item IO::AIO::max_poll_time $seconds	1962	=item IO::AIO::max_poll_time $seconds
1644		1963
…		…
1671	poll => 'r', nice => 1,	1990	poll => 'r', nice => 1,
1672	cb => &IO::AIO::poll_cb);	1991	cb => &IO::AIO::poll_cb);
1673		1992
1674	=back	1993	=back
1675		1994
		1995
1676	=head3 CONTROLLING THE NUMBER OF THREADS	1996	=head3 CONTROLLING THE NUMBER OF THREADS
1677		1997
1678	=over	1998	=over
1679		1999
1680	=item IO::AIO::min_parallel $nthreads	2000	=item IO::AIO::min_parallel $nthreads
…		…
1745		2065
1746	This is a very bad function to use in interactive programs because it	2066	This is a very bad function to use in interactive programs because it
1747	blocks, and a bad way to reduce concurrency because it is inexact: Better	2067	blocks, and a bad way to reduce concurrency because it is inexact: Better
1748	use an C<aio_group> together with a feed callback.	2068	use an C<aio_group> together with a feed callback.
1749		2069
1750	It's main use is in scripts without an event loop - when you want to stat	2070	Its main use is in scripts without an event loop - when you want to stat
1751	a lot of files, you can write somehting like this:	2071	a lot of files, you can write something like this:
1752		2072
1753	IO::AIO::max_outstanding 32;	2073	IO::AIO::max_outstanding 32;
1754		2074
1755	for my $path (...) {	2075	for my $path (...) {
1756	aio_stat $path , ...;	2076	aio_stat $path , ...;
…		…
1767	The default value for C<max_outstanding> is very large, so there is no	2087	The default value for C<max_outstanding> is very large, so there is no
1768	practical limit on the number of outstanding requests.	2088	practical limit on the number of outstanding requests.
1769		2089
1770	=back	2090	=back
1771		2091
		2092
1772	=head3 STATISTICAL INFORMATION	2093	=head3 STATISTICAL INFORMATION
1773		2094
1774	=over	2095	=over
1775		2096
1776	=item IO::AIO::nreqs	2097	=item IO::AIO::nreqs
…		…
1793	Returns the number of requests currently in the pending state (executed,	2114	Returns the number of requests currently in the pending state (executed,
1794	but not yet processed by poll_cb).	2115	but not yet processed by poll_cb).
1795		2116
1796	=back	2117	=back
1797		2118
		2119
		2120	=head3 SUBSECOND STAT TIME ACCESS
		2121
		2122	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2123	generally find access/modification and change times with subsecond time
		2124	accuracy of the system supports it, but perl's built-in functions only
		2125	return the integer part.
		2126
		2127	The following functions return the timestamps of the most recent
		2128	stat with subsecond precision on most systems and work both after
		2129	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2130	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2131	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2132
		2133	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2134	full resolution without rounding and work with standard perl C<stat>,
		2135	alleviating the need to call the special C<Time::HiRes> functions, which
		2136	do not act like their perl counterparts.
		2137
		2138	On operating systems or file systems where subsecond time resolution is
		2139	not supported or could not be detected, a fractional part of C<0> is
		2140	returned, so it is always safe to call these functions.
		2141
		2142	=over 4
		2143
		2144	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		2145
		2146	Return the access, modication, change or birth time, respectively,
		2147	including fractional part. Due to the limited precision of floating point,
		2148	the accuracy on most platforms is only a bit better than milliseconds
		2149	for times around now - see the I<nsec> function family, below, for full
		2150	accuracy.
		2151
		2152	File birth time is only available when the OS and perl support it (on
		2153	FreeBSD and NetBSD at the time of this writing, although support is
		2154	adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
		2155	it). On systems where it isn't available, C<0> is currently returned, but
		2156	this might change to C<undef> in a future version.
		2157
		2158	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		2159
		2160	Returns access, modification, change and birth time all in one go, and
		2161	maybe more times in the future version.
		2162
		2163	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		2164
		2165	Return the fractional access, modifcation, change or birth time, in nanoseconds,
		2166	as an integer in the range C<0> to C<999999999>.
		2167
		2168	Note that no accessors are provided for access, modification and
		2169	change times - you need to get those from C<stat _> if required (C<int
		2170	IO::AIO::st_atime> and so on will I<not> generally give you the correct
		2171	value).
		2172
		2173	=item $seconds = IO::AIO::st_btimesec
		2174
		2175	The (integral) seconds part of the file birth time, if available.
		2176
		2177	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		2178
		2179	Like the functions above, but returns all four times in one go (and maybe
		2180	more in future versions).
		2181
		2182	=item $counter = IO::AIO::st_gen
		2183
		2184	Returns the generation counter (in practice this is just a random number)
		2185	of the file. This is only available on platforms which have this member in
		2186	their C<struct stat> (most BSDs at the time of this writing) and generally
		2187	only to the root usert. If unsupported, C<0> is returned, but this might
		2188	change to C<undef> in a future version.
		2189
		2190	=back
		2191
		2192	Example: print the high resolution modification time of F</etc>, using
		2193	C<stat>, and C<IO::AIO::aio_stat>.
		2194
		2195	if (stat "/etc") {
		2196	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2197	}
		2198
		2199	IO::AIO::aio_stat "/etc", sub {
		2200	$_[0]
		2201	and return;
		2202
		2203	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2204	};
		2205
		2206	IO::AIO::flush;
		2207
		2208	Output of the awbove on my system, showing reduced and full accuracy:
		2209
		2210	stat(/etc) mtime: 1534043702.020808
		2211	aio_stat(/etc) mtime: 1534043702.020807792
		2212
		2213
1798	=head3 MISCELLANEOUS FUNCTIONS	2214	=head3 MISCELLANEOUS FUNCTIONS
1799		2215
1800	IO::AIO implements some functions that might be useful, but are not	2216	IO::AIO implements some functions that are useful when you want to use
1801	asynchronous.	2217	some "Advanced I/O" function not available to in Perl, without going the
		2218	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2219	counterpart.
1802		2220
1803	=over 4	2221	=over 4
		2222
		2223	=item $numfd = IO::AIO::get_fdlimit
		2224
		2225	Tries to find the current file descriptor limit and returns it, or
		2226	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2227	the highest valid file descriptor number.
		2228
		2229	=item IO::AIO::min_fdlimit [$numfd]
		2230
		2231	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2232	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2233	is missing, it will try to set a very high limit, although this is not
		2234	recommended when you know the actual minimum that you require.
		2235
		2236	If the limit cannot be raised enough, the function makes a best-effort
		2237	attempt to increase the limit as much as possible, using various
		2238	tricks, while still failing. You can query the resulting limit using
		2239	C<IO::AIO::get_fdlimit>.
		2240
		2241	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2242	true.
1804		2243
1805	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2244	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1806		2245
1807	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2246	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1808	but is blocking (this makes most sense if you know the input data is	2247	but is blocking (this makes most sense if you know the input data is
…		…
1825	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2264	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1826		2265
1827	Simply calls the C<posix_madvise> function (see its	2266	Simply calls the C<posix_madvise> function (see its
1828	manpage for details). The following advice constants are	2267	manpage for details). The following advice constants are
1829	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2268	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1830	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2269	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2270	C<IO::AIO::MADV_DONTNEED>.
		2271
		2272	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2273	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2274	will be reduced to fit into the C<$scalar>.
1831		2275
1832	On systems that do not implement C<posix_madvise>, this function returns	2276	On systems that do not implement C<posix_madvise>, this function returns
1833	ENOSYS, otherwise the return value of C<posix_madvise>.	2277	ENOSYS, otherwise the return value of C<posix_madvise>.
1834		2278
1835	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2279	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
…		…
1837	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2281	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1838	$scalar (see its manpage for details). The following protect	2282	$scalar (see its manpage for details). The following protect
1839	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2283	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1840	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2284	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1841		2285
		2286	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2287	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2288	will be reduced to fit into the C<$scalar>.
		2289
1842	On systems that do not implement C<mprotect>, this function returns	2290	On systems that do not implement C<mprotect>, this function returns
1843	ENOSYS, otherwise the return value of C<mprotect>.	2291	ENOSYS, otherwise the return value of C<mprotect>.
1844		2292
1845	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2293	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1846		2294
1847	Memory-maps a file (or anonymous memory range) and attaches it to the	2295	Memory-maps a file (or anonymous memory range) and attaches it to the
1848	given C<$scalar>, which will act like a string scalar.	2296	given C<$scalar>, which will act like a string scalar. Returns true on
		2297	success, and false otherwise.
1849		2298
		2299	The scalar must exist, but its contents do not matter - this means you
		2300	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2301	the scalar first.
		2302
1850	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2303	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1851	change the string length, and most read-only operations such as copying it	2304	which don't change the string length, and most read-only operations such
1852	or searching it with regexes and so on.	2305	as copying it or searching it with regexes and so on.
1853		2306
1854	Anything else is unsafe and will, at best, result in memory leaks.	2307	Anything else is unsafe and will, at best, result in memory leaks.
1855		2308
1856	The memory map associated with the C<$scalar> is automatically removed	2309	The memory map associated with the C<$scalar> is automatically removed
1857	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2310	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1858	C<IO::AIO::munmap> functions are called.	2311	or C<IO::AIO::munmap> functions are called on it.
1859		2312
1860	This calls the C<mmap>(2) function internally. See your system's manual	2313	This calls the C<mmap>(2) function internally. See your system's manual
1861	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2314	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1862		2315
1863	The C<$length> must be larger than zero and smaller than the actual	2316	The C<$length> must be larger than zero and smaller than the actual
1864	filesize.	2317	filesize.
1865		2318
1866	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2319	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1867	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2320	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1868		2321
1869	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2322	C<$flags> can be a combination of
1870	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2323	C<IO::AIO::MAP_SHARED> or
1871	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2324	C<IO::AIO::MAP_PRIVATE>,
		2325	or a number of system-specific flags (when not available, the are C<0>):
1872	(which is set to C<MAP_ANON> if your system only provides this	2326	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1873	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2327	C<IO::AIO::MAP_LOCKED>,
1874	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2328	C<IO::AIO::MAP_NORESERVE>,
		2329	C<IO::AIO::MAP_POPULATE>,
1875	C<IO::AIO::MAP_NONBLOCK>	2330	C<IO::AIO::MAP_NONBLOCK>,
		2331	C<IO::AIO::MAP_FIXED>,
		2332	C<IO::AIO::MAP_GROWSDOWN>,
		2333	C<IO::AIO::MAP_32BIT>,
		2334	C<IO::AIO::MAP_HUGETLB> or
		2335	C<IO::AIO::MAP_STACK>.
1876		2336
1877	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2337	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1878		2338
1879	C<$offset> is the offset from the start of the file - it generally must be	2339	C<$offset> is the offset from the start of the file - it generally must be
1880	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2340	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1894		2354
1895	=item IO::AIO::munmap $scalar	2355	=item IO::AIO::munmap $scalar
1896		2356
1897	Removes a previous mmap and undefines the C<$scalar>.	2357	Removes a previous mmap and undefines the C<$scalar>.
1898		2358
		2359	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2360
		2361	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2362	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2363	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2364
		2365	Returns true if successful, and false otherwise. If the underlying mmapped
		2366	region has changed address, then the true value has the numerical value
		2367	C<1>, otherwise it has the numerical value C<0>:
		2368
		2369	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2370	or die "mremap: $!";
		2371
		2372	if ($success*1) {
		2373	warn "scalar has chanegd address in memory\n";
		2374	}
		2375
		2376	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2377	implemented, but not supported and might go away in a future version.
		2378
		2379	On systems where this call is not supported or is not emulated, this call
		2380	returns falls and sets C<$!> to C<ENOSYS>.
		2381
		2382	=item IO::AIO::mlockall $flags
		2383
		2384	Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
		2385	but is blocking.
		2386
1899	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef	2387	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1900		2388
1901	Calls the C<munlock> function, undoing the effects of a previous	2389	Calls the C<munlock> function, undoing the effects of a previous
1902	C<aio_mlock> call (see its description for details).	2390	C<aio_mlock> call (see its description for details).
1903		2391
…		…
1905		2393
1906	Calls the C<munlockall> function.	2394	Calls the C<munlockall> function.
1907		2395
1908	On systems that do not implement C<munlockall>, this function returns	2396	On systems that do not implement C<munlockall>, this function returns
1909	ENOSYS, otherwise the return value of C<munlockall>.	2397	ENOSYS, otherwise the return value of C<munlockall>.
		2398
		2399	=item $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		2400
		2401	Uses the GNU/Linux C<accept4(2)> syscall, if available, to accept a socket
		2402	and return the new file handle on success, or sets C<$!> and returns
		2403	C<undef> on error.
		2404
		2405	The remote name of the new socket will be stored in C<$sockaddr>, which
		2406	will be extended to allow for at least C<$sockaddr_maxlen> octets. If the
		2407	socket name does not fit into C<$sockaddr_maxlen> octets, this is signaled
		2408	by returning a longer string in C<$sockaddr>, which might or might not be
		2409	truncated.
		2410
		2411	To accept name-less sockets, use C<undef> for C<$sockaddr> and C<0> for
		2412	C<$sockaddr_maxlen>.
		2413
		2414	The main reasons to use this syscall rather than portable C<accept(2)>
		2415	are that you can specify C<SOCK_NONBLOCK> and/or C<SOCK_CLOEXEC>
		2416	flags and you can accept name-less sockets by specifying C<0> for
		2417	C<$sockaddr_maxlen>, which is sadly not possible with perl's interface to
		2418	C<accept>.
		2419
		2420	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2421
		2422	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2423	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2424	should be the file offset.
		2425
		2426	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2427	silently corrupt the data in this case.
		2428
		2429	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2430	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2431	C<IO::AIO::SPLICE_F_GIFT>.
		2432
		2433	See the C<splice(2)> manpage for details.
		2434
		2435	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2436
		2437	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2438	description for C<IO::AIO::splice> above for details.
		2439
		2440	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2441
		2442	Attempts to query or change the pipe buffer size. Obviously works only
		2443	on pipes, and currently works only on GNU/Linux systems, and fails with
		2444	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2445	size on other systems, drop me a note.
		2446
		2447	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2448
		2449	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2450	C<$flags> is missing or C<0>, then this should be the same as a call to
		2451	perl's built-in C<pipe> function and create a new pipe, and works on
		2452	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2453	(..., 4096, O_BINARY)>.
		2454
		2455	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2456	the given flags (Linux 2.6.27, glibc 2.9).
		2457
		2458	On success, the read and write file handles are returned.
		2459
		2460	On error, nothing will be returned. If the pipe2 syscall is missing and
		2461	C<$flags> is non-zero, fails with C<ENOSYS>.
		2462
		2463	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2464	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2465	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2466
		2467	Example: create a pipe race-free w.r.t. threads and fork:
		2468
		2469	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2470	or die "pipe2: $!\n";
		2471
		2472	=item $fh = IO::AIO::memfd_create $pathname[, $flags]
		2473
		2474	This is a direct interface to the Linux L<memfd_create(2)> system
		2475	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2476	should be C<IO::AIO::MFD_CLOEXEC>.
		2477
		2478	On success, the new memfd filehandle is returned, otherwise returns
		2479	C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
		2480
		2481	Please refer to L<memfd_create(2)> for more info on this call.
		2482
		2483	The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
		2484	C<IO::AIO::MFD_ALLOW_SEALING> and C<IO::AIO::MFD_HUGETLB>.
		2485
		2486	Example: create a new memfd.
		2487
		2488	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2489	or die "memfd_create: $!\n";
		2490
		2491	=item $fh = IO::AIO::pidfd_open $pid[, $flags]
		2492
		2493	This is an interface to the Linux L<pidfd_open(2)> system call. The
		2494	default for C<$flags> is C<0>.
		2495
		2496	On success, a new pidfd filehandle is returned (that is already set to
		2497	close-on-exec), otherwise returns C<undef>. If the syscall is missing,
		2498	fails with C<ENOSYS>.
		2499
		2500	Example: open pid 6341 as pidfd.
		2501
		2502	my $fh = IO::AIO::pidfd_open 6341
		2503	or die "pidfd_open: $!\n";
		2504
		2505	=item $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		2506
		2507	This is an interface to the Linux L<pidfd_send_signal> system call. The
		2508	default for C<$siginfo> is C<undef> and the default for C<$flags> is C<0>.
		2509
		2510	Returns the system call status. If the syscall is missing, fails with
		2511	C<ENOSYS>.
		2512
		2513	When specified, C<$siginfo> must be a reference to a hash with one or more
		2514	of the following members:
		2515
		2516	=over
		2517
		2518	=item code - the C<si_code> member
		2519
		2520	=item pid - the C<si_pid> member
		2521
		2522	=item uid - the C<si_uid> member
		2523
		2524	=item value_int - the C<si_value.sival_int> member
		2525
		2526	=item value_ptr - the C<si_value.sival_ptr> member, specified as an integer
		2527
		2528	=back
		2529
		2530	Example: send a SIGKILL to the specified process.
		2531
		2532	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
		2533	and die "pidfd_send_signal: $!\n";
		2534
		2535	Example: send a SIGKILL to the specified process with extra data.
		2536
		2537	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
		2538	and die "pidfd_send_signal: $!\n";
		2539
		2540	=item $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		2541
		2542	This is an interface to the Linux L<pidfd_getfd> system call. The default
		2543	for C<$flags> is C<0>.
		2544
		2545	On success, returns a dup'ed copy of the target file descriptor (specified
		2546	as an integer) returned (that is already set to close-on-exec), otherwise
		2547	returns C<undef>. If the syscall is missing, fails with C<ENOSYS>.
		2548
		2549	Example: get a copy of standard error of another process and print soemthing to it.
		2550
		2551	my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
		2552	or die "pidfd_getfd: $!\n";
		2553	print $errfh "stderr\n";
		2554
		2555	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2556
		2557	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2558	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2559
		2560	On success, the new eventfd filehandle is returned, otherwise returns
		2561	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2562
		2563	Please refer to L<eventfd(2)> for more info on this call.
		2564
		2565	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2566	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2567
		2568	Example: create a new eventfd filehandle:
		2569
		2570	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2571	or die "eventfd: $!\n";
		2572
		2573	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2574
		2575	This is a direct interface to the Linux L<timerfd_create(2)> system
		2576	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2577	should be C<IO::AIO::TFD_CLOEXEC>.
		2578
		2579	On success, the new timerfd filehandle is returned, otherwise returns
		2580	C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
		2581
		2582	Please refer to L<timerfd_create(2)> for more info on this call.
		2583
		2584	The following C<$clockid> values are
		2585	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2586	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2587	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2588	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2589
		2590	The following C<$flags> values are available (Linux
		2591	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2592
		2593	Example: create a new timerfd and set it to one-second repeated alarms,
		2594	then wait for two alarms:
		2595
		2596	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2597	or die "timerfd_create: $!\n";
		2598
		2599	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2600	or die "timerfd_settime: $!\n";
		2601
		2602	for (1..2) {
		2603	8 == sysread $fh, my $buf, 8
		2604	or die "timerfd read failure\n";
		2605
		2606	printf "number of expirations (likely 1): %d\n",
		2607	unpack "Q", $buf;
		2608	}
		2609
		2610	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2611
		2612	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2613	call. Please refer to its manpage for more info on this call.
		2614
		2615	The new itimerspec is specified using two (possibly fractional) second
		2616	values, C<$new_interval> and C<$new_value>).
		2617
		2618	On success, the current interval and value are returned (as per
		2619	C<timerfd_gettime>). On failure, the empty list is returned.
		2620
		2621	The following C<$flags> values are
		2622	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2623	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2624
		2625	See C<IO::AIO::timerfd_create> for a full example.
		2626
		2627	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2628
		2629	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2630	call. Please refer to its manpage for more info on this call.
		2631
		2632	On success, returns the current values of interval and value for the given
		2633	timerfd (as potentially fractional second values). On failure, the empty
		2634	list is returned.
1910		2635
1911	=back	2636	=back
1912		2637
1913	=cut	2638	=cut
1914		2639
…		…
1980	the process will result in undefined behaviour. Calling it at any time	2705	the process will result in undefined behaviour. Calling it at any time
1981	will also result in any undefined (by POSIX) behaviour.	2706	will also result in any undefined (by POSIX) behaviour.
1982		2707
1983	=back	2708	=back
1984		2709
		2710	=head2 LINUX-SPECIFIC CALLS
		2711
		2712	When a call is documented as "linux-specific" then this means it
		2713	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2714	availability and compatibility of such calls regardless of the platform
		2715	it is compiled on, so platforms such as FreeBSD which often implement
		2716	these calls will work. When in doubt, call them and see if they fail wth
		2717	C<ENOSYS>.
		2718
1985	=head2 MEMORY USAGE	2719	=head2 MEMORY USAGE
1986		2720
1987	Per-request usage:	2721	Per-request usage:
1988		2722
1989	Each aio request uses - depending on your architecture - around 100-200	2723	Each aio request uses - depending on your architecture - around 100-200
…		…
2001	temporary buffers, and each thread requires a stack and other data	2735	temporary buffers, and each thread requires a stack and other data
2002	structures (usually around 16k-128k, depending on the OS).	2736	structures (usually around 16k-128k, depending on the OS).
2003		2737
2004	=head1 KNOWN BUGS	2738	=head1 KNOWN BUGS
2005		2739
2006	Known bugs will be fixed in the next release.	2740	Known bugs will be fixed in the next release :)
		2741
		2742	=head1 KNOWN ISSUES
		2743
		2744	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2745	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2746	non-created hash slots or other scalars I didn't think of. It's best to
		2747	avoid such and either use scalar variables or making sure that the scalar
		2748	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2749
		2750	I am not sure anything can be done about this, so this is considered a
		2751	known issue, rather than a bug.
2007		2752
2008	=head1 SEE ALSO	2753	=head1 SEE ALSO
2009		2754
2010	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2755	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
2011	more natural syntax.	2756	more natural syntax and L<IO::FDPass> for file descriptor passing.
2012		2757
2013	=head1 AUTHOR	2758	=head1 AUTHOR
2014		2759
2015	Marc Lehmann <schmorp@schmorp.de>	2760	Marc Lehmann <schmorp@schmorp.de>
2016	http://home.schmorp.de/	2761	http://home.schmorp.de/

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