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Revision 1.201 by root, Tue Jul 5 09:24:11 2011 UTC vs.
Revision 1.317 by root, Sun Sep 25 16:30:50 2022 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 = '3.93';	176	our $VERSION = 4.79;
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 aio_fsync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead	181	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
		182	aio_pathsync aio_readahead aio_fiemap aio_allocate
179	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
180	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
181	aio_chmod aio_utime aio_truncate	185	aio_chmod aio_utime aio_truncate
182	aio_msync aio_mtouch aio_mlock aio_mlockall	186	aio_msync aio_mtouch aio_mlock aio_mlockall
183	aio_statvfs);	187	aio_statvfs
		188	aio_slurp
		189	aio_wd);
184		190
185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	191	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	192	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
187	min_parallel max_parallel max_idle idle_timeout	193	min_parallel max_parallel max_idle idle_timeout
188	nreqs nready npending nthreads	194	nreqs nready npending nthreads
189	max_poll_time max_poll_reqs	195	max_poll_time max_poll_reqs
190	sendfile fadvise madvise	196	sendfile fadvise madvise
191	mmap munmap munlock munlockall);	197	mmap munmap mremap munlock munlockall
		198
		199	accept4 tee splice pipe2 pipesize
		200	fexecve mount umount memfd_create eventfd
		201	timerfd_create timerfd_settime timerfd_gettime
		202	pidfd_open pidfd_send_signal pidfd_getfd);
192		203
193	push @AIO_REQ, qw(aio_busy); # not exported	204	push @AIO_REQ, qw(aio_busy); # not exported
194		205
195	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	206	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
196		207
…		…
200		211
201	=head1 FUNCTIONS	212	=head1 FUNCTIONS
202		213
203	=head2 QUICK OVERVIEW	214	=head2 QUICK OVERVIEW
204		215
205	This section simply lists the prototypes of the most important functions	216	This section simply lists the prototypes most of the functions for
206	for quick reference. See the following sections for function-by-function	217	quick reference. See the following sections for function-by-function
207	documentation.	218	documentation.
208		219
		220	aio_wd $pathname, $callback->($wd)
209	aio_open $pathname, $flags, $mode, $callback->($fh)	221	aio_open $pathname, $flags, $mode, $callback->($fh)
210	aio_close $fh, $callback->($status)	222	aio_close $fh, $callback->($status)
		223	aio_seek $fh,$offset,$whence, $callback->($offs)
211	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	224	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
212	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	225	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
213	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	226	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
214	aio_readahead $fh,$offset,$length, $callback->($retval)	227	aio_readahead $fh,$offset,$length, $callback->($retval)
215	aio_stat $fh_or_path, $callback->($status)	228	aio_stat $fh_or_path, $callback->($status)
216	aio_lstat $fh, $callback->($status)	229	aio_lstat $fh, $callback->($status)
217	aio_statvfs $fh_or_path, $callback->($statvfs)	230	aio_statvfs $fh_or_path, $callback->($statvfs)
218	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	231	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
219	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	232	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		233	aio_chmod $fh_or_path, $mode, $callback->($status)
220	aio_truncate $fh_or_path, $offset, $callback->($status)	234	aio_truncate $fh_or_path, $offset, $callback->($status)
221	aio_chmod $fh_or_path, $mode, $callback->($status)	235	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		236	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
222	aio_unlink $pathname, $callback->($status)	237	aio_unlink $pathname, $callback->($status)
223	aio_mknod $path, $mode, $dev, $callback->($status)	238	aio_mknod $pathname, $mode, $dev, $callback->($status)
224	aio_link $srcpath, $dstpath, $callback->($status)	239	aio_link $srcpath, $dstpath, $callback->($status)
225	aio_symlink $srcpath, $dstpath, $callback->($status)	240	aio_symlink $srcpath, $dstpath, $callback->($status)
226	aio_readlink $path, $callback->($link)	241	aio_readlink $pathname, $callback->($link)
227	aio_realpath $path, $callback->($link)	242	aio_realpath $pathname, $callback->($path)
228	aio_rename $srcpath, $dstpath, $callback->($status)	243	aio_rename $srcpath, $dstpath, $callback->($status)
		244	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
229	aio_mkdir $pathname, $mode, $callback->($status)	245	aio_mkdir $pathname, $mode, $callback->($status)
230	aio_rmdir $pathname, $callback->($status)	246	aio_rmdir $pathname, $callback->($status)
231	aio_readdir $pathname, $callback->($entries)	247	aio_readdir $pathname, $callback->($entries)
232	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	248	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
233	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	249	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
234	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	250	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		251	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
235	aio_load $path, $data, $callback->($status)	252	aio_load $pathname, $data, $callback->($status)
236	aio_copy $srcpath, $dstpath, $callback->($status)	253	aio_copy $srcpath, $dstpath, $callback->($status)
237	aio_move $srcpath, $dstpath, $callback->($status)	254	aio_move $srcpath, $dstpath, $callback->($status)
238	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
239	aio_rmtree $path, $callback->($status)	255	aio_rmtree $pathname, $callback->($status)
		256	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		257	aio_ioctl $fh, $request, $buf, $callback->($status)
240	aio_sync $callback->($status)	258	aio_sync $callback->($status)
		259	aio_syncfs $fh, $callback->($status)
241	aio_fsync $fh, $callback->($status)	260	aio_fsync $fh, $callback->($status)
242	aio_fdatasync $fh, $callback->($status)	261	aio_fdatasync $fh, $callback->($status)
243	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	262	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
244	aio_pathsync $path, $callback->($status)	263	aio_pathsync $pathname, $callback->($status)
245	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	264	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
246	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	265	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
247	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	266	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
248	aio_mlockall $flags, $callback->($status)	267	aio_mlockall $flags, $callback->($status)
249	aio_group $callback->(...)	268	aio_group $callback->(...)
250	aio_nop $callback->()	269	aio_nop $callback->()
…		…
264	IO::AIO::idle_timeout $seconds	283	IO::AIO::idle_timeout $seconds
265	IO::AIO::max_outstanding $maxreqs	284	IO::AIO::max_outstanding $maxreqs
266	IO::AIO::nreqs	285	IO::AIO::nreqs
267	IO::AIO::nready	286	IO::AIO::nready
268	IO::AIO::npending	287	IO::AIO::npending
		288	IO::AIO::reinit
		289
		290	$nfd = IO::AIO::get_fdlimit
		291	IO::AIO::min_fdlimit $nfd
269		292
270	IO::AIO::sendfile $ofh, $ifh, $offset, $count	293	IO::AIO::sendfile $ofh, $ifh, $offset, $count
271	IO::AIO::fadvise $fh, $offset, $len, $advice	294	IO::AIO::fadvise $fh, $offset, $len, $advice
		295	IO::AIO::fexecve $fh, $argv, $envp
		296
		297	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		298	IO::AIO::munmap $scalar
		299	IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
272	IO::AIO::madvise $scalar, $offset, $length, $advice	300	IO::AIO::madvise $scalar, $offset, $length, $advice
273	IO::AIO::mprotect $scalar, $offset, $length, $protect	301	IO::AIO::mprotect $scalar, $offset, $length, $protect
274	IO::AIO::munlock $scalar, $offset = 0, $length = undef	302	IO::AIO::munlock $scalar, $offset = 0, $length = undef
275	IO::AIO::munlockall	303	IO::AIO::munlockall
276		304
277	=head2 AIO REQUEST FUNCTIONS	305	# stat extensions
		306	$counter = IO::AIO::st_gen
		307	$seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		308	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		309	$nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		310	$seconds = IO::AIO::st_btimesec
		311	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		312
		313	# very much unportable syscalls
		314	IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
		315	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		316	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		317
		318	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		319	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		320
		321	$fh = IO::AIO::eventfd [$initval, [$flags]]
		322	$fh = IO::AIO::memfd_create $pathname[, $flags]
		323
		324	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		325	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		326	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		327
		328	$fh = IO::AIO::pidfd_open $pid[, $flags]
		329	$status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		330	$fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		331
		332	$retval = IO::AIO::mount $special, $path, $fstype, $flags = 0, $data = undef
		333	$retval = IO::AIO::umount $path, $flags = 0
		334
		335	=head2 API NOTES
278		336
279	All the C<aio_*> calls are more or less thin wrappers around the syscall	337	All the C<aio_*> calls are more or less thin wrappers around the syscall
280	with the same name (sans C<aio_>). The arguments are similar or identical,	338	with the same name (sans C<aio_>). The arguments are similar or identical,
281	and they all accept an additional (and optional) C<$callback> argument	339	and they all accept an additional (and optional) C<$callback> argument
282	which must be a code reference. This code reference will get called with	340	which must be a code reference. This code reference will be called after
283	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	341	the syscall has been executed in an asynchronous fashion. The results
284	perl, which usually delivers "false") as its sole argument after the given	342	of the request will be passed as arguments to the callback (and, if an
285	syscall has been executed asynchronously.	343	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		344	most syscalls return C<-1> on error, unlike perl, which usually delivers
		345	"false").
		346
		347	Some requests (such as C<aio_readdir>) pass the actual results and
		348	communicate failures by passing C<undef>.
286		349
287	All functions expecting a filehandle keep a copy of the filehandle	350	All functions expecting a filehandle keep a copy of the filehandle
288	internally until the request has finished.	351	internally until the request has finished.
289		352
290	All functions return request objects of type L<IO::AIO::REQ> that allow	353	All functions return request objects of type L<IO::AIO::REQ> that allow
291	further manipulation of those requests while they are in-flight.	354	further manipulation of those requests while they are in-flight.
292		355
293	The pathnames you pass to these routines I<must> be absolute and	356	The pathnames you pass to these routines I<should> be absolute. The
294	encoded as octets. The reason for the former is that at the time the	357	reason for this is that at the time the request is being executed, the
295	request is being executed, the current working directory could have	358	current working directory could have changed. Alternatively, you can
296	changed. Alternatively, you can make sure that you never change the	359	make sure that you never change the current working directory anywhere
297	current working directory anywhere in the program and then use relative	360	in the program and then use relative paths. You can also take advantage
298	paths.	361	of IO::AIOs working directory abstraction, that lets you specify paths
		362	relative to some previously-opened "working directory object" - see the
		363	description of the C<IO::AIO::WD> class later in this document.
299		364
300	To encode pathnames as octets, either make sure you either: a) always pass	365	To encode pathnames as octets, either make sure you either: a) always pass
301	in filenames you got from outside (command line, readdir etc.) without	366	in filenames you got from outside (command line, readdir etc.) without
302	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	367	tinkering, b) are in your native filesystem encoding, c) use the Encode
303	your pathnames to the locale (or other) encoding in effect in the user	368	module and encode your pathnames to the locale (or other) encoding in
304	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	369	effect in the user environment, d) use Glib::filename_from_unicode on
305	use something else to ensure your scalar has the correct contents.	370	unicode filenames or e) use something else to ensure your scalar has the
		371	correct contents.
306		372
307	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	373	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
308	handles correctly whether it is set or not.	374	handles correctly whether it is set or not.
		375
		376	=head2 AIO REQUEST FUNCTIONS
309		377
310	=over 4	378	=over 4
311		379
312	=item $prev_pri = aioreq_pri [$pri]	380	=item $prev_pri = aioreq_pri [$pri]
313		381
…		…
343		411
344		412
345	=item aio_open $pathname, $flags, $mode, $callback->($fh)	413	=item aio_open $pathname, $flags, $mode, $callback->($fh)
346		414
347	Asynchronously open or create a file and call the callback with a newly	415	Asynchronously open or create a file and call the callback with a newly
348	created filehandle for the file.	416	created filehandle for the file (or C<undef> in case of an error).
349		417
350	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	418	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
351	for an explanation.	419	for an explanation.
352		420
353	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	421	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
376	following POSIX and non-POSIX constants are available (missing ones on	444	following POSIX and non-POSIX constants are available (missing ones on
377	your system are, as usual, C<0>):	445	your system are, as usual, C<0>):
378		446
379	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,	447	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
380	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,	448	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
381	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.	449	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
382		450
383		451
384	=item aio_close $fh, $callback->($status)	452	=item aio_close $fh, $callback->($status)
385		453
386	Asynchronously close a file and call the callback with the result	454	Asynchronously close a file and call the callback with the result
…		…
396	Or in other words: the file descriptor will be closed, but it will not be	464	Or in other words: the file descriptor will be closed, but it will not be
397	free for reuse until the perl filehandle is closed.	465	free for reuse until the perl filehandle is closed.
398		466
399	=cut	467	=cut
400		468
		469	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		470
		471	Seeks the filehandle to the new C<$offset>, similarly to perl's
		472	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		473	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		474	C<IO::AIO::SEEK_END>).
		475
		476	The resulting absolute offset will be passed to the callback, or C<-1> in
		477	case of an error.
		478
		479	In theory, the C<$whence> constants could be different than the
		480	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		481	so don't panic.
		482
		483	As a GNU/Linux (and maybe Solaris) extension, also the constants
		484	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		485	could be found. No guarantees about suitability for use in C<aio_seek> or
		486	Perl's C<sysseek> can be made though, although I would naively assume they
		487	"just work".
		488
401	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	489	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
402		490
403	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	491	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
404		492
405	Reads or writes C<$length> bytes from or to the specified C<$fh> and	493	Reads or writes C<$length> bytes from or to the specified C<$fh> and
406	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	494	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
407	and calls the callback without the actual number of bytes read (or -1 on	495	calls the callback with the actual number of bytes transferred (or -1 on
408	error, just like the syscall).	496	error, just like the syscall).
409		497
410	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	498	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
411	offset plus the actual number of bytes read.	499	offset plus the actual number of bytes read.
412		500
…		…
470	As native sendfile syscalls (as practically any non-POSIX interface hacked	558	As native sendfile syscalls (as practically any non-POSIX interface hacked
471	together in a hurry to improve benchmark numbers) tend to be rather buggy	559	together in a hurry to improve benchmark numbers) tend to be rather buggy
472	on many systems, this implementation tries to work around some known bugs	560	on many systems, this implementation tries to work around some known bugs
473	in Linux and FreeBSD kernels (probably others, too), but that might fail,	561	in Linux and FreeBSD kernels (probably others, too), but that might fail,
474	so you really really should check the return value of C<aio_sendfile> -	562	so you really really should check the return value of C<aio_sendfile> -
475	fewre bytes than expected might have been transferred.	563	fewer bytes than expected might have been transferred.
476		564
477		565
478	=item aio_readahead $fh,$offset,$length, $callback->($retval)	566	=item aio_readahead $fh,$offset,$length, $callback->($retval)
479		567
480	C<aio_readahead> populates the page cache with data from a file so that	568	C<aio_readahead> populates the page cache with data from a file so that
…		…
484	whole pages, so that offset is effectively rounded down to a page boundary	572	whole pages, so that offset is effectively rounded down to a page boundary
485	and bytes are read up to the next page boundary greater than or equal to	573	and bytes are read up to the next page boundary greater than or equal to
486	(off-set+length). C<aio_readahead> does not read beyond the end of the	574	(off-set+length). C<aio_readahead> does not read beyond the end of the
487	file. The current file offset of the file is left unchanged.	575	file. The current file offset of the file is left unchanged.
488		576
489	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	577	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
490	emulated by simply reading the data, which would have a similar effect.	578	be emulated by simply reading the data, which would have a similar effect.
491		579
492		580
493	=item aio_stat $fh_or_path, $callback->($status)	581	=item aio_stat $fh_or_path, $callback->($status)
494		582
495	=item aio_lstat $fh, $callback->($status)	583	=item aio_lstat $fh, $callback->($status)
496		584
497	Works like perl's C<stat> or C<lstat> in void context. The callback will	585	Works almost exactly like perl's C<stat> or C<lstat> in void context. The
498	be called after the stat and the results will be available using C<stat _>	586	callback will be called after the stat and the results will be available
499	or C<-s _> etc...	587	using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
		588	and C<-T>).
500		589
501	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,	590	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
502	for an explanation.	591	for an explanation.
503		592
504	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	593	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
…		…
511	behaviour).	600	behaviour).
512		601
513	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,	602	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
514	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,	603	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
515	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.	604	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		605
		606	To access higher resolution stat timestamps, see L<SUBSECOND STAT TIME
		607	ACCESS>.
516		608
517	Example: Print the length of F</etc/passwd>:	609	Example: Print the length of F</etc/passwd>:
518		610
519	aio_stat "/etc/passwd", sub {	611	aio_stat "/etc/passwd", sub {
520	$_[0] and die "stat failed: $!";	612	$_[0] and die "stat failed: $!";
…		…
564	namemax => 255,	656	namemax => 255,
565	frsize => 1024,	657	frsize => 1024,
566	fsid => 1810	658	fsid => 1810
567	}	659	}
568		660
569
570	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	661	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
571		662
572	Works like perl's C<utime> function (including the special case of $atime	663	Works like perl's C<utime> function (including the special case of $atime
573	and $mtime being undef). Fractional times are supported if the underlying	664	and $mtime being undef). Fractional times are supported if the underlying
574	syscalls support them.	665	syscalls support them.
575		666
576	When called with a pathname, uses utimes(2) if available, otherwise	667	When called with a pathname, uses utimensat(2) or utimes(2) if available,
577	utime(2). If called on a file descriptor, uses futimes(2) if available,	668	otherwise utime(2). If called on a file descriptor, uses futimens(2)
578	otherwise returns ENOSYS, so this is not portable.	669	or futimes(2) if available, otherwise returns ENOSYS, so this is not
		670	portable.
579		671
580	Examples:	672	Examples:
581		673
582	# set atime and mtime to current time (basically touch(1)):	674	# set atime and mtime to current time (basically touch(1)):
583	aio_utime "path", undef, undef;	675	aio_utime "path", undef, undef;
…		…
601	=item aio_truncate $fh_or_path, $offset, $callback->($status)	693	=item aio_truncate $fh_or_path, $offset, $callback->($status)
602		694
603	Works like truncate(2) or ftruncate(2).	695	Works like truncate(2) or ftruncate(2).
604		696
605		697
		698	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		699
		700	Allocates or frees disk space according to the C<$mode> argument. See the
		701	linux C<fallocate> documentation for details.
		702
		703	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		704	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		705	to deallocate a file range.
		706
		707	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		708	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		709	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		710	to unshare shared blocks (see your L<fallocate(2)> manpage).
		711
		712	The file system block size used by C<fallocate> is presumably the
		713	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		714	can dictate other limitations.
		715
		716	If C<fallocate> isn't available or cannot be emulated (currently no
		717	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		718
		719
606	=item aio_chmod $fh_or_path, $mode, $callback->($status)	720	=item aio_chmod $fh_or_path, $mode, $callback->($status)
607		721
608	Works like perl's C<chmod> function.	722	Works like perl's C<chmod> function.
609		723
610		724
…		…
612		726
613	Asynchronously unlink (delete) a file and call the callback with the	727	Asynchronously unlink (delete) a file and call the callback with the
614	result code.	728	result code.
615		729
616		730
617	=item aio_mknod $path, $mode, $dev, $callback->($status)	731	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
618		732
619	[EXPERIMENTAL]	733	[EXPERIMENTAL]
620		734
621	Asynchronously create a device node (or fifo). See mknod(2).	735	Asynchronously create a device node (or fifo). See mknod(2).
622		736
623	The only (POSIX-) portable way of calling this function is:	737	The only (POSIX-) portable way of calling this function is:
624		738
625	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	739	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
626		740
627	See C<aio_stat> for info about some potentially helpful extra constants	741	See C<aio_stat> for info about some potentially helpful extra constants
628	and functions.	742	and functions.
629		743
630	=item aio_link $srcpath, $dstpath, $callback->($status)	744	=item aio_link $srcpath, $dstpath, $callback->($status)
…		…
637		751
638	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	752	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
639	the path C<$dstpath> and call the callback with the result code.	753	the path C<$dstpath> and call the callback with the result code.
640		754
641		755
642	=item aio_readlink $path, $callback->($link)	756	=item aio_readlink $pathname, $callback->($link)
643		757
644	Asynchronously read the symlink specified by C<$path> and pass it to	758	Asynchronously read the symlink specified by C<$path> and pass it to
645	the callback. If an error occurs, nothing or undef gets passed to the	759	the callback. If an error occurs, nothing or undef gets passed to the
646	callback.	760	callback.
647		761
648		762
649	=item aio_realpath $path, $callback->($path)	763	=item aio_realpath $pathname, $callback->($path)
650		764
651	Asynchronously make the path absolute and resolve any symlinks in	765	Asynchronously make the path absolute and resolve any symlinks in
652	C<$path>. The resulting path only consists of directories.	766	C<$path>. The resulting path only consists of directories (same as
		767	L<Cwd::realpath>).
653		768
654	This request can be used to get the absolute path of the current working	769	This request can be used to get the absolute path of the current working
655	directory by passing it a path of F<.> (a single dot).	770	directory by passing it a path of F<.> (a single dot).
656		771
657		772
658	=item aio_rename $srcpath, $dstpath, $callback->($status)	773	=item aio_rename $srcpath, $dstpath, $callback->($status)
659		774
660	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	775	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
661	rename(2) and call the callback with the result code.	776	rename(2) and call the callback with the result code.
		777
		778	On systems that support the AIO::WD working directory abstraction
		779	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		780	of failing, C<rename> is called on the absolute path of C<$wd>.
		781
		782
		783	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		784
		785	Basically a version of C<aio_rename> with an additional C<$flags>
		786	argument. Calling this with C<$flags=0> is the same as calling
		787	C<aio_rename>.
		788
		789	Non-zero flags are currently only supported on GNU/Linux systems that
		790	support renameat2. Other systems fail with C<ENOSYS> in this case.
		791
		792	The following constants are available (missing ones are, as usual C<0>),
		793	see renameat2(2) for details:
		794
		795	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		796	and C<IO::AIO::RENAME_WHITEOUT>.
662		797
663		798
664	=item aio_mkdir $pathname, $mode, $callback->($status)	799	=item aio_mkdir $pathname, $mode, $callback->($status)
665		800
666	Asynchronously mkdir (create) a directory and call the callback with	801	Asynchronously mkdir (create) a directory and call the callback with
…		…
671	=item aio_rmdir $pathname, $callback->($status)	806	=item aio_rmdir $pathname, $callback->($status)
672		807
673	Asynchronously rmdir (delete) a directory and call the callback with the	808	Asynchronously rmdir (delete) a directory and call the callback with the
674	result code.	809	result code.
675		810
		811	On systems that support the AIO::WD working directory abstraction
		812	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		813	C<rmdir> is called on the absolute path of C<$wd>.
		814
676		815
677	=item aio_readdir $pathname, $callback->($entries)	816	=item aio_readdir $pathname, $callback->($entries)
678		817
679	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	818	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
680	directory (i.e. opendir + readdir + closedir). The entries will not be	819	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
684	array-ref with the filenames.	823	array-ref with the filenames.
685		824
686		825
687	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	826	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
688		827
689	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	828	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
690	behaviour and output format. In case of an error, C<$entries> will be	829	tune behaviour and output format. In case of an error, C<$entries> will be
691	C<undef>.	830	C<undef>.
692		831
693	The flags are a combination of the following constants, ORed together (the	832	The flags are a combination of the following constants, ORed together (the
694	flags will also be passed to the callback, possibly modified):	833	flags will also be passed to the callback, possibly modified):
695		834
696	=over 4	835	=over 4
697		836
698	=item IO::AIO::READDIR_DENTS	837	=item IO::AIO::READDIR_DENTS
699		838
700	When this flag is off, then the callback gets an arrayref consisting of	839	Normally the callback gets an arrayref consisting of names only (as
701	names only (as with C<aio_readdir>), otherwise it gets an arrayref with	840	with C<aio_readdir>). If this flag is set, then the callback gets an
702	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	841	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
703	entry in more detail.	842	single directory entry in more detail:
704		843
705	C<$name> is the name of the entry.	844	C<$name> is the name of the entry.
706		845
707	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	846	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
708		847
709	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	848	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
710	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	849	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
711	C<IO::AIO::DT_WHT>.	850	C<IO::AIO::DT_WHT>.
712		851
713	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	852	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
714	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	853	to know, you have to run stat yourself. Also, for speed/memory reasons,
715	scalars are read-only: you can not modify them.	854	the C<$type> scalars are read-only: you must not modify them.
716		855
717	C<$inode> is the inode number (which might not be exact on systems with 64	856	C<$inode> is the inode number (which might not be exact on systems with 64
718	bit inode numbers and 32 bit perls). This field has unspecified content on	857	bit inode numbers and 32 bit perls). This field has unspecified content on
719	systems that do not deliver the inode information.	858	systems that do not deliver the inode information.
720		859
…		…
731	short names are tried first.	870	short names are tried first.
732		871
733	=item IO::AIO::READDIR_STAT_ORDER	872	=item IO::AIO::READDIR_STAT_ORDER
734		873
735	When this flag is set, then the names will be returned in an order	874	When this flag is set, then the names will be returned in an order
736	suitable for stat()'ing each one. That is, when you plan to stat()	875	suitable for stat()'ing each one. That is, when you plan to stat() most or
737	all files in the given directory, then the returned order will likely	876	all files in the given directory, then the returned order will likely be
738	be fastest.	877	faster.
739		878
740	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then	879	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
741	the likely dirs come first, resulting in a less optimal stat order.	880	then the likely dirs come first, resulting in a less optimal stat order
		881	for stat'ing all entries, but likely a more optimal order for finding
		882	subdirectories.
742		883
743	=item IO::AIO::READDIR_FOUND_UNKNOWN	884	=item IO::AIO::READDIR_FOUND_UNKNOWN
744		885
745	This flag should not be set when calling C<aio_readdirx>. Instead, it	886	This flag should not be set when calling C<aio_readdirx>. Instead, it
746	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	887	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
747	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	888	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
748	C<$type>'s are known, which can be used to speed up some algorithms.	889	C<$type>'s are known, which can be used to speed up some algorithms.
749		890
750	=back	891	=back
751		892
752		893
		894	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		895
		896	Opens, reads and closes the given file. The data is put into C<$data>,
		897	which is resized as required.
		898
		899	If C<$offset> is negative, then it is counted from the end of the file.
		900
		901	If C<$length> is zero, then the remaining length of the file is
		902	used. Also, in this case, the same limitations to modifying C<$data> apply
		903	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		904	with C<substr>. If the size of the file is known, specifying a non-zero
		905	C<$length> results in a performance advantage.
		906
		907	This request is similar to the older C<aio_load> request, but since it is
		908	a single request, it might be more efficient to use.
		909
		910	Example: load F</etc/passwd> into C<$passwd>.
		911
		912	my $passwd;
		913	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		914	$_[0] >= 0
		915	or die "/etc/passwd: $!\n";
		916
		917	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		918	print $passwd;
		919	};
		920	IO::AIO::flush;
		921
		922
753	=item aio_load $path, $data, $callback->($status)	923	=item aio_load $pathname, $data, $callback->($status)
754		924
755	This is a composite request that tries to fully load the given file into	925	This is a composite request that tries to fully load the given file into
756	memory. Status is the same as with aio_read.	926	memory. Status is the same as with aio_read.
		927
		928	Using C<aio_slurp> might be more efficient, as it is a single request.
757		929
758	=cut	930	=cut
759		931
760	sub aio_load($$;$) {	932	sub aio_load($$;$) {
761	my ($path, undef, $cb) = @_;	933	my ($path, undef, $cb) = @_;
…		…
781	=item aio_copy $srcpath, $dstpath, $callback->($status)	953	=item aio_copy $srcpath, $dstpath, $callback->($status)
782		954
783	Try to copy the I<file> (directories not supported as either source or	955	Try to copy the I<file> (directories not supported as either source or
784	destination) from C<$srcpath> to C<$dstpath> and call the callback with	956	destination) from C<$srcpath> to C<$dstpath> and call the callback with
785	a status of C<0> (ok) or C<-1> (error, see C<$!>).	957	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		958
		959	Existing destination files will be truncated.
786		960
787	This is a composite request that creates the destination file with	961	This is a composite request that creates the destination file with
788	mode 0200 and copies the contents of the source file into it using	962	mode 0200 and copies the contents of the source file into it using
789	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	963	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
790	uid/gid, in that order.	964	uid/gid, in that order.
…		…
893	};	1067	};
894		1068
895	$grp	1069	$grp
896	}	1070	}
897		1071
898	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1072	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
899		1073
900	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1074	Scans a directory (similar to C<aio_readdir>) but additionally tries to
901	efficiently separate the entries of directory C<$path> into two sets of	1075	efficiently separate the entries of directory C<$path> into two sets of
902	names, directories you can recurse into (directories), and ones you cannot	1076	names, directories you can recurse into (directories), and ones you cannot
903	recurse into (everything else, including symlinks to directories).	1077	recurse into (everything else, including symlinks to directories).
904		1078
905	C<aio_scandir> is a composite request that creates of many sub requests_	1079	C<aio_scandir> is a composite request that generates many sub requests.
906	C<$maxreq> specifies the maximum number of outstanding aio requests that	1080	C<$maxreq> specifies the maximum number of outstanding aio requests that
907	this function generates. If it is C<< <= 0 >>, then a suitable default	1081	this function generates. If it is C<< <= 0 >>, then a suitable default
908	will be chosen (currently 4).	1082	will be chosen (currently 4).
909		1083
910	On error, the callback is called without arguments, otherwise it receives	1084	On error, the callback is called without arguments, otherwise it receives
…		…
934	Then entries will be sorted into likely directories a non-initial dot	1108	Then entries will be sorted into likely directories a non-initial dot
935	currently) and likely non-directories (see C<aio_readdirx>). Then every	1109	currently) and likely non-directories (see C<aio_readdirx>). Then every
936	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1110	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
937	in order of their inode numbers. If that succeeds, it assumes that the	1111	in order of their inode numbers. If that succeeds, it assumes that the
938	entry is a directory or a symlink to directory (which will be checked	1112	entry is a directory or a symlink to directory (which will be checked
939	seperately). This is often faster than stat'ing the entry itself because	1113	separately). This is often faster than stat'ing the entry itself because
940	filesystems might detect the type of the entry without reading the inode	1114	filesystems might detect the type of the entry without reading the inode
941	data (e.g. ext2fs filetype feature), even on systems that cannot return	1115	data (e.g. ext2fs filetype feature), even on systems that cannot return
942	the filetype information on readdir.	1116	the filetype information on readdir.
943		1117
944	If the known number of directories (link count - 2) has been reached, the	1118	If the known number of directories (link count - 2) has been reached, the
…		…
960		1134
961	my $grp = aio_group $cb;	1135	my $grp = aio_group $cb;
962		1136
963	$maxreq = 4 if $maxreq <= 0;	1137	$maxreq = 4 if $maxreq <= 0;
964		1138
965	# stat once	1139	# get a wd object
966	aioreq_pri $pri;	1140	aioreq_pri $pri;
967	add $grp aio_stat $path, sub {	1141	add $grp aio_wd $path, sub {
		1142	$_[0]
968	return $grp->result () if $_[0];	1143	or return $grp->result ();
969	my $now = time;
970	my $hash1 = join ":", (stat _)[0,1,3,7,9];
971		1144
972	# read the directory entries	1145	my $wd = [shift, "."];
		1146
		1147	# stat once
973	aioreq_pri $pri;	1148	aioreq_pri $pri;
974	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1149	add $grp aio_stat $wd, sub {
975	my $entries = shift
976	or return $grp->result ();	1150	return $grp->result () if $_[0];
		1151	my $now = time;
		1152	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		1153	my $rdxflags = READDIR_DIRS_FIRST;
977		1154
978	# stat the dir another time	1155	if ((stat _)[3] < 2) {
		1156	# at least one non-POSIX filesystem exists
		1157	# that returns useful DT_type values: btrfs,
		1158	# so optimise for this here by requesting dents
		1159	$rdxflags |= READDIR_DENTS;
		1160	}
		1161
		1162	# read the directory entries
979	aioreq_pri $pri;	1163	aioreq_pri $pri;
980	add $grp aio_stat $path, sub {	1164	add $grp aio_readdirx $wd, $rdxflags, sub {
981	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1165	my ($entries, $flags) = @_
		1166	or return $grp->result ();
982		1167
		1168	if ($rdxflags & READDIR_DENTS) {
		1169	# if we requested type values, see if we can use them directly.
		1170
		1171	# if there were any DT_UNKNOWN entries then we assume we
		1172	# don't know. alternatively, we could assume that if we get
		1173	# one DT_DIR, then all directories are indeed marked with
		1174	# DT_DIR, but this seems not required for btrfs, and this
		1175	# is basically the "btrfs can't get it's act together" code
		1176	# branch.
		1177	unless ($flags & READDIR_FOUND_UNKNOWN) {
		1178	# now we have valid DT_ information for all entries,
		1179	# so use it as an optimisation without further stat's.
		1180	# they must also all be at the beginning of @$entries
		1181	# by now.
		1182
983	my $ndirs;	1183	my $dirs;
984		1184
985	# take the slow route if anything looks fishy
986	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
987	$ndirs = -1;
988	} else {
989	# if nlink == 2, we are finished
990	# for non-posix-fs's, we rely on nlink < 2
991	$ndirs = (stat _)[3] - 2
992	or return $grp->result ([], $entries);
993	}
994
995	my (@dirs, @nondirs);
996
997	my $statgrp = add $grp aio_group sub {
998	$grp->result (\@dirs, \@nondirs);
999	};
1000
1001	limit $statgrp $maxreq;
1002	feed $statgrp sub {
1003	return unless @$entries;
1004	my $entry = shift @$entries;
1005
1006	aioreq_pri $pri;
1007	add $statgrp aio_stat "$path/$entry/.", sub {
1008	if ($_[0] < 0) {	1185	if (@$entries) {
1009	push @nondirs, $entry;	1186	for (0 .. $#$entries) {
1010	} else {	1187	if ($entries->[$_][1] != DT_DIR) {
1011	# need to check for real directory	1188	# splice out directories
1012	aioreq_pri $pri;	1189	$dirs = [splice @$entries, 0, $_];
1013	add $statgrp aio_lstat "$path/$entry", sub {
1014	if (-d _) {
1015	push @dirs, $entry;
1016
1017	unless (--$ndirs) {
1018	push @nondirs, @$entries;
1019	feed $statgrp;
1020	}	1190	last;
1021	} else {
1022	push @nondirs, $entry;
1023	}	1191	}
1024	}	1192	}
		1193
		1194	# if we didn't find any non-dir, then all entries are dirs
		1195	unless ($dirs) {
		1196	($dirs, $entries) = ($entries, []);
		1197	}
		1198	} else {
		1199	# directory is empty, so there are no sbdirs
		1200	$dirs = [];
1025	}	1201	}
		1202
		1203	# either splice'd the directories out or the dir was empty.
		1204	# convert dents to filenames
		1205	$_ = $_->[0] for @$dirs;
		1206	$_ = $_->[0] for @$entries;
		1207
		1208	return $grp->result ($dirs, $entries);
		1209	}
		1210
		1211	# cannot use, so return to our old ways
		1212	# by pretending we only scanned for names.
		1213	$_ = $_->[0] for @$entries;
		1214	}
		1215
		1216	# stat the dir another time
		1217	aioreq_pri $pri;
		1218	add $grp aio_stat $wd, sub {
		1219	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		1220
		1221	my $ndirs;
		1222
		1223	# take the slow route if anything looks fishy
		1224	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
		1225	$ndirs = -1;
		1226	} else {
		1227	# if nlink == 2, we are finished
		1228	# for non-posix-fs's, we rely on nlink < 2
		1229	$ndirs = (stat _)[3] - 2
		1230	or return $grp->result ([], $entries);
		1231	}
		1232
		1233	my (@dirs, @nondirs);
		1234
		1235	my $statgrp = add $grp aio_group sub {
		1236	$grp->result (\@dirs, \@nondirs);
		1237	};
		1238
		1239	limit $statgrp $maxreq;
		1240	feed $statgrp sub {
		1241	return unless @$entries;
		1242	my $entry = shift @$entries;
		1243
		1244	aioreq_pri $pri;
		1245	$wd->[1] = "$entry/.";
		1246	add $statgrp aio_stat $wd, sub {
		1247	if ($_[0] < 0) {
		1248	push @nondirs, $entry;
		1249	} else {
		1250	# need to check for real directory
		1251	aioreq_pri $pri;
		1252	$wd->[1] = $entry;
		1253	add $statgrp aio_lstat $wd, sub {
		1254	if (-d _) {
		1255	push @dirs, $entry;
		1256
		1257	unless (--$ndirs) {
		1258	push @nondirs, @$entries;
		1259	feed $statgrp;
		1260	}
		1261	} else {
		1262	push @nondirs, $entry;
		1263	}
		1264	}
		1265	}
		1266	};
1026	};	1267	};
1027	};	1268	};
1028	};	1269	};
1029	};	1270	};
1030	};	1271	};
1031		1272
1032	$grp	1273	$grp
1033	}	1274	}
1034		1275
1035	=item aio_rmtree $path, $callback->($status)	1276	=item aio_rmtree $pathname, $callback->($status)
1036		1277
1037	Delete a directory tree starting (and including) C<$path>, return the	1278	Delete a directory tree starting (and including) C<$path>, return the
1038	status of the final C<rmdir> only. This is a composite request that	1279	status of the final C<rmdir> only. This is a composite request that
1039	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1280	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1040	everything else.	1281	everything else.
1041		1282
1042	=cut	1283	=cut
1043		1284
…		…
1065	};	1306	};
1066		1307
1067	$grp	1308	$grp
1068	}	1309	}
1069		1310
		1311	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1312
		1313	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1314
		1315	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1316	they execute asynchronously and pass the return value to the callback.
		1317
		1318	Both calls can be used for a lot of things, some of which make more sense
		1319	to run asynchronously in their own thread, while some others make less
		1320	sense. For example, calls that block waiting for external events, such
		1321	as locking, will also lock down an I/O thread while it is waiting, which
		1322	can deadlock the whole I/O system. At the same time, there might be no
		1323	alternative to using a thread to wait.
		1324
		1325	So in general, you should only use these calls for things that do
		1326	(filesystem) I/O, not for things that wait for other events (network,
		1327	other processes), although if you are careful and know what you are doing,
		1328	you still can.
		1329
		1330	The following constants are available and can be used for normal C<ioctl>
		1331	and C<fcntl> as well (missing ones are, as usual C<0>):
		1332
		1333	C<F_DUPFD_CLOEXEC>,
		1334
		1335	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1336
		1337	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1338
		1339	C<F_ADD_SEALS>, C<F_GET_SEALS>, C<F_SEAL_SEAL>, C<F_SEAL_SHRINK>, C<F_SEAL_GROW> and
		1340	C<F_SEAL_WRITE>.
		1341
		1342	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1343	C<FS_IOC_FIEMAP>.
		1344
		1345	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1346	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1347
		1348	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1349	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1350	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1351	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1352	C<FS_FL_USER_MODIFIABLE>.
		1353
		1354	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1355	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1356	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1357	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1358
		1359	C<BLKROSET>, C<BLKROGET>, C<BLKRRPART>, C<BLKGETSIZE>, C<BLKFLSBUF>, C<BLKRASET>,
		1360	C<BLKRAGET>, C<BLKFRASET>, C<BLKFRAGET>, C<BLKSECTSET>, C<BLKSECTGET>, C<BLKSSZGET>,
		1361	C<BLKBSZGET>, C<BLKBSZSET>, C<BLKGETSIZE64>,
		1362
		1363
1070	=item aio_sync $callback->($status)	1364	=item aio_sync $callback->($status)
1071		1365
1072	Asynchronously call sync and call the callback when finished.	1366	Asynchronously call sync and call the callback when finished.
1073		1367
1074	=item aio_fsync $fh, $callback->($status)	1368	=item aio_fsync $fh, $callback->($status)
…		…
1081	Asynchronously call fdatasync on the given filehandle and call the	1375	Asynchronously call fdatasync on the given filehandle and call the
1082	callback with the fdatasync result code.	1376	callback with the fdatasync result code.
1083		1377
1084	If this call isn't available because your OS lacks it or it couldn't be	1378	If this call isn't available because your OS lacks it or it couldn't be
1085	detected, it will be emulated by calling C<fsync> instead.	1379	detected, it will be emulated by calling C<fsync> instead.
		1380
		1381	=item aio_syncfs $fh, $callback->($status)
		1382
		1383	Asynchronously call the syncfs syscall to sync the filesystem associated
		1384	to the given filehandle and call the callback with the syncfs result
		1385	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1386	errno to C<ENOSYS> nevertheless.
1086		1387
1087	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1388	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1088		1389
1089	Sync the data portion of the file specified by C<$offset> and C<$length>	1390	Sync the data portion of the file specified by C<$offset> and C<$length>
1090	to disk (but NOT the metadata), by calling the Linux-specific	1391	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1094	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1395	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1095	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1396	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1096	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1397	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1097	manpage for details.	1398	manpage for details.
1098		1399
1099	=item aio_pathsync $path, $callback->($status)	1400	=item aio_pathsync $pathname, $callback->($status)
1100		1401
1101	This request tries to open, fsync and close the given path. This is a	1402	This request tries to open, fsync and close the given path. This is a
1102	composite request intended to sync directories after directory operations	1403	composite request intended to sync directories after directory operations
1103	(E.g. rename). This might not work on all operating systems or have any	1404	(E.g. rename). This might not work on all operating systems or have any
1104	specific effect, but usually it makes sure that directory changes get	1405	specific effect, but usually it makes sure that directory changes get
…		…
1135	};	1436	};
1136		1437
1137	$grp	1438	$grp
1138	}	1439	}
1139		1440
1140	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1441	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1141		1442
1142	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1443	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1143	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1444	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1144	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1445	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1145	scalar must only be modified in-place while an aio operation is pending on	1446	scalar must only be modified in-place while an aio operation is pending on
…		…
1147		1448
1148	It calls the C<msync> function of your OS, if available, with the memory	1449	It calls the C<msync> function of your OS, if available, with the memory
1149	area starting at C<$offset> in the string and ending C<$length> bytes	1450	area starting at C<$offset> in the string and ending C<$length> bytes
1150	later. If C<$length> is negative, counts from the end, and if C<$length>	1451	later. If C<$length> is negative, counts from the end, and if C<$length>
1151	is C<undef>, then it goes till the end of the string. The flags can be	1452	is C<undef>, then it goes till the end of the string. The flags can be
1152	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1453	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1153	C<IO::AIO::MS_SYNC>.	1454	C<IO::AIO::MS_INVALIDATE>.
1154		1455
1155	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1456	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1156		1457
1157	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1458	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1158	scalars.	1459	scalars.
1159		1460
1160	It touches (reads or writes) all memory pages in the specified	1461	It touches (reads or writes) all memory pages in the specified
1161	range inside the scalar. All caveats and parameters are the same	1462	range inside the scalar. All caveats and parameters are the same
1162	as for C<aio_msync>, above, except for flags, which must be either	1463	as for C<aio_msync>, above, except for flags, which must be either
1163	C<0> (which reads all pages and ensures they are instantiated) or	1464	C<0> (which reads all pages and ensures they are instantiated) or
1164	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1465	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1165	writing an octet from it, which dirties the page).	1466	writing an octet from it, which dirties the page).
1166		1467
1167	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1468	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1168		1469
1169	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1470	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1188	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;	1489	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1189	aio_mlock $data; # mlock in background	1490	aio_mlock $data; # mlock in background
1190		1491
1191	=item aio_mlockall $flags, $callback->($status)	1492	=item aio_mlockall $flags, $callback->($status)
1192		1493
1193	Calls the C<mlockall> function with the given C<$flags> (a combination of	1494	Calls the C<mlockall> function with the given C<$flags> (a
1194	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).	1495	combination of C<IO::AIO::MCL_CURRENT>, C<IO::AIO::MCL_FUTURE> and
		1496	C<IO::AIO::MCL_ONFAULT>).
1195		1497
1196	On systems that do not implement C<mlockall>, this function returns C<-1>	1498	On systems that do not implement C<mlockall>, this function returns C<-1>
1197	and sets errno to C<ENOSYS>.	1499	and sets errno to C<ENOSYS>. Similarly, flag combinations not supported
		1500	by the system result in a return value of C<-1> with errno being set to
		1501	C<EINVAL>.
1198		1502
1199	Note that the corresponding C<munlockall> is synchronous and is	1503	Note that the corresponding C<munlockall> is synchronous and is
1200	documented under L<MISCELLANEOUS FUNCTIONS>.	1504	documented under L<MISCELLANEOUS FUNCTIONS>.
1201		1505
1202	Example: asynchronously lock all current and future pages into memory.	1506	Example: asynchronously lock all current and future pages into memory.
1203		1507
1204	aio_mlockall IO::AIO::MCL_FUTURE;	1508	aio_mlockall IO::AIO::MCL_FUTURE;
		1509
		1510	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1511
		1512	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1513	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1514	the ioctl is not available on your OS, then this request will fail with
		1515	C<ENOSYS>.
		1516
		1517	C<$start> is the starting offset to query extents for, C<$length> is the
		1518	size of the range to query - if it is C<undef>, then the whole file will
		1519	be queried.
		1520
		1521	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1522	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1523	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1524	the data portion.
		1525
		1526	C<$count> is the maximum number of extent records to return. If it is
		1527	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1528	case, if it is C<0>, then the callback receives the number of extents
		1529	instead of the extents themselves (which is unreliable, see below).
		1530
		1531	If an error occurs, the callback receives no arguments. The special
		1532	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1533
		1534	Otherwise, the callback receives an array reference with extent
		1535	structures. Each extent structure is an array reference itself, with the
		1536	following members:
		1537
		1538	[$logical, $physical, $length, $flags]
		1539
		1540	Flags is any combination of the following flag values (typically either C<0>
		1541	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1542
		1543	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1544	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1545	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1546	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1547	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1548	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1549
		1550	At the time of this writing (Linux 3.2), this request is unreliable unless
		1551	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1552	it to return all extents of a range for files with a large number of
		1553	extents. The code (only) works around all these issues if C<$count> is
		1554	C<undef>.
1205		1555
1206	=item aio_group $callback->(...)	1556	=item aio_group $callback->(...)
1207		1557
1208	This is a very special aio request: Instead of doing something, it is a	1558	This is a very special aio request: Instead of doing something, it is a
1209	container for other aio requests, which is useful if you want to bundle	1559	container for other aio requests, which is useful if you want to bundle
…		…
1246	like sleep and file handle readable/writable, the overhead this creates is	1596	like sleep and file handle readable/writable, the overhead this creates is
1247	immense (it blocks a thread for a long time) so do not use this function	1597	immense (it blocks a thread for a long time) so do not use this function
1248	except to put your application under artificial I/O pressure.	1598	except to put your application under artificial I/O pressure.
1249		1599
1250	=back	1600	=back
		1601
		1602
		1603	=head2 IO::AIO::WD - multiple working directories
		1604
		1605	Your process only has one current working directory, which is used by all
		1606	threads. This makes it hard to use relative paths (some other component
		1607	could call C<chdir> at any time, and it is hard to control when the path
		1608	will be used by IO::AIO).
		1609
		1610	One solution for this is to always use absolute paths. This usually works,
		1611	but can be quite slow (the kernel has to walk the whole path on every
		1612	access), and can also be a hassle to implement.
		1613
		1614	Newer POSIX systems have a number of functions (openat, fdopendir,
		1615	futimensat and so on) that make it possible to specify working directories
		1616	per operation.
		1617
		1618	For portability, and because the clowns who "designed", or shall I write,
		1619	perpetrated this new interface were obviously half-drunk, this abstraction
		1620	cannot be perfect, though.
		1621
		1622	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1623	object. This object stores the canonicalised, absolute version of the
		1624	path, and on systems that allow it, also a directory file descriptor.
		1625
		1626	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1627	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1628	object and a pathname instead (or the IO::AIO::WD object alone, which
		1629	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1630	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1631	to that IO::AIO::WD object.
		1632
		1633	For example, to get a wd object for F</etc> and then stat F<passwd>
		1634	inside, you would write:
		1635
		1636	aio_wd "/etc", sub {
		1637	my $etcdir = shift;
		1638
		1639	# although $etcdir can be undef on error, there is generally no reason
		1640	# to check for errors here, as aio_stat will fail with ENOENT
		1641	# when $etcdir is undef.
		1642
		1643	aio_stat [$etcdir, "passwd"], sub {
		1644	# yay
		1645	};
		1646	};
		1647
		1648	The fact that C<aio_wd> is a request and not a normal function shows that
		1649	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1650	which is why it is done asynchronously.
		1651
		1652	To stat the directory obtained with C<aio_wd> above, one could write
		1653	either of the following three request calls:
		1654
		1655	aio_lstat "/etc" , sub { ... # pathname as normal string
		1656	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1657	aio_lstat $wd , sub { ... # shorthand for the previous
		1658
		1659	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1660	object and the pathname string, so you could write the following without
		1661	causing any issues due to C<$path> getting reused:
		1662
		1663	my $path = [$wd, undef];
		1664
		1665	for my $name (qw(abc def ghi)) {
		1666	$path->[1] = $name;
		1667	aio_stat $path, sub {
		1668	# ...
		1669	};
		1670	}
		1671
		1672	There are some caveats: when directories get renamed (or deleted), the
		1673	pathname string doesn't change, so will point to the new directory (or
		1674	nowhere at all), while the directory fd, if available on the system,
		1675	will still point to the original directory. Most functions accepting a
		1676	pathname will use the directory fd on newer systems, and the string on
		1677	older systems. Some functions (such as C<aio_realpath>) will always rely on
		1678	the string form of the pathname.
		1679
		1680	So this functionality is mainly useful to get some protection against
		1681	C<chdir>, to easily get an absolute path out of a relative path for future
		1682	reference, and to speed up doing many operations in the same directory
		1683	(e.g. when stat'ing all files in a directory).
		1684
		1685	The following functions implement this working directory abstraction:
		1686
		1687	=over 4
		1688
		1689	=item aio_wd $pathname, $callback->($wd)
		1690
		1691	Asynchonously canonicalise the given pathname and convert it to an
		1692	IO::AIO::WD object representing it. If possible and supported on the
		1693	system, also open a directory fd to speed up pathname resolution relative
		1694	to this working directory.
		1695
		1696	If something goes wrong, then C<undef> is passwd to the callback instead
		1697	of a working directory object and C<$!> is set appropriately. Since
		1698	passing C<undef> as working directory component of a pathname fails the
		1699	request with C<ENOENT>, there is often no need for error checking in the
		1700	C<aio_wd> callback, as future requests using the value will fail in the
		1701	expected way.
		1702
		1703	=item IO::AIO::CWD
		1704
		1705	This is a compile time constant (object) that represents the process
		1706	current working directory.
		1707
		1708	Specifying this object as working directory object for a pathname is as if
		1709	the pathname would be specified directly, without a directory object. For
		1710	example, these calls are functionally identical:
		1711
		1712	aio_stat "somefile", sub { ... };
		1713	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1714
		1715	=back
		1716
		1717	To recover the path associated with an IO::AIO::WD object, you can use
		1718	C<aio_realpath>:
		1719
		1720	aio_realpath $wd, sub {
		1721	warn "path is $_[0]\n";
		1722	};
		1723
		1724	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1725	sometimes, fall back to using an absolue path.
1251		1726
1252	=head2 IO::AIO::REQ CLASS	1727	=head2 IO::AIO::REQ CLASS
1253		1728
1254	All non-aggregate C<aio_*> functions return an object of this class when	1729	All non-aggregate C<aio_*> functions return an object of this class when
1255	called in non-void context.	1730	called in non-void context.
…		…
1373		1848
1374	Sets a feeder/generator on this group: every group can have an attached	1849	Sets a feeder/generator on this group: every group can have an attached
1375	generator that generates requests if idle. The idea behind this is that,	1850	generator that generates requests if idle. The idea behind this is that,
1376	although you could just queue as many requests as you want in a group,	1851	although you could just queue as many requests as you want in a group,
1377	this might starve other requests for a potentially long time. For example,	1852	this might starve other requests for a potentially long time. For example,
1378	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1853	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1379	delaying any later requests for a long time.	1854	requests, delaying any later requests for a long time.
1380		1855
1381	To avoid this, and allow incremental generation of requests, you can	1856	To avoid this, and allow incremental generation of requests, you can
1382	instead a group and set a feeder on it that generates those requests. The	1857	instead a group and set a feeder on it that generates those requests. The
1383	feed callback will be called whenever there are few enough (see C<limit>,	1858	feed callback will be called whenever there are few enough (see C<limit>,
1384	below) requests active in the group itself and is expected to queue more	1859	below) requests active in the group itself and is expected to queue more
…		…
1416	The default value for the limit is C<0>, but note that setting a feeder	1891	The default value for the limit is C<0>, but note that setting a feeder
1417	automatically bumps it up to C<2>.	1892	automatically bumps it up to C<2>.
1418		1893
1419	=back	1894	=back
1420		1895
		1896
1421	=head2 SUPPORT FUNCTIONS	1897	=head2 SUPPORT FUNCTIONS
1422		1898
1423	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1899	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1424		1900
1425	=over 4	1901	=over 4
…		…
1433		1909
1434	See C<poll_cb> for an example.	1910	See C<poll_cb> for an example.
1435		1911
1436	=item IO::AIO::poll_cb	1912	=item IO::AIO::poll_cb
1437		1913
1438	Process some outstanding events on the result pipe. You have to call	1914	Process some requests that have reached the result phase (i.e. they have
		1915	been executed but the results are not yet reported). You have to call
		1916	this "regularly" to finish outstanding requests.
		1917
1439	this regularly. Returns C<0> if all events could be processed (or there	1918	Returns C<0> if all events could be processed (or there were no
1440	were no events to process), or C<-1> if it returned earlier for whatever	1919	events to process), or C<-1> if it returned earlier for whatever
1441	reason. Returns immediately when no events are outstanding. The amount of	1920	reason. Returns immediately when no events are outstanding. The amount
1442	events processed depends on the settings of C<IO::AIO::max_poll_req> and	1921	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1443	C<IO::AIO::max_poll_time>.	1922	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1444		1923
1445	If not all requests were processed for whatever reason, the filehandle	1924	If not all requests were processed for whatever reason, the poll file
1446	will still be ready when C<poll_cb> returns, so normally you don't have to	1925	descriptor will still be ready when C<poll_cb> returns, so normally you
1447	do anything special to have it called later.	1926	don't have to do anything special to have it called later.
1448		1927
1449	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1928	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1450	ready, it can be beneficial to call this function from loops which submit	1929	ready, it can be beneficial to call this function from loops which submit
1451	a lot of requests, to make sure the results get processed when they become	1930	a lot of requests, to make sure the results get processed when they become
1452	available and not just when the loop is finished and the event loop takes	1931	available and not just when the loop is finished and the event loop takes
…		…
1461	poll => 'r', async => 1,	1940	poll => 'r', async => 1,
1462	cb => \&IO::AIO::poll_cb);	1941	cb => \&IO::AIO::poll_cb);
1463		1942
1464	=item IO::AIO::poll_wait	1943	=item IO::AIO::poll_wait
1465		1944
1466	If there are any outstanding requests and none of them in the result	1945	Wait until either at least one request is in the result phase or no
1467	phase, wait till the result filehandle becomes ready for reading (simply	1946	requests are outstanding anymore.
1468	does a C<select> on the filehandle. This is useful if you want to	1947
1469	synchronously wait for some requests to finish).	1948	This is useful if you want to synchronously wait for some requests to
		1949	become ready, without actually handling them.
1470		1950
1471	See C<nreqs> for an example.	1951	See C<nreqs> for an example.
1472		1952
1473	=item IO::AIO::poll	1953	=item IO::AIO::poll
1474		1954
…		…
1485		1965
1486	Strictly equivalent to:	1966	Strictly equivalent to:
1487		1967
1488	IO::AIO::poll_wait, IO::AIO::poll_cb	1968	IO::AIO::poll_wait, IO::AIO::poll_cb
1489	while IO::AIO::nreqs;	1969	while IO::AIO::nreqs;
		1970
		1971	This function can be useful at program aborts, to make sure outstanding
		1972	I/O has been done (C<IO::AIO> uses an C<END> block which already calls
		1973	this function on normal exits), or when you are merely using C<IO::AIO>
		1974	for its more advanced functions, rather than for async I/O, e.g.:
		1975
		1976	my ($dirs, $nondirs);
		1977	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1978	IO::AIO::flush;
		1979	# $dirs, $nondirs are now set
1490		1980
1491	=item IO::AIO::max_poll_reqs $nreqs	1981	=item IO::AIO::max_poll_reqs $nreqs
1492		1982
1493	=item IO::AIO::max_poll_time $seconds	1983	=item IO::AIO::max_poll_time $seconds
1494		1984
…		…
1521	poll => 'r', nice => 1,	2011	poll => 'r', nice => 1,
1522	cb => &IO::AIO::poll_cb);	2012	cb => &IO::AIO::poll_cb);
1523		2013
1524	=back	2014	=back
1525		2015
		2016
1526	=head3 CONTROLLING THE NUMBER OF THREADS	2017	=head3 CONTROLLING THE NUMBER OF THREADS
1527		2018
1528	=over	2019	=over
1529		2020
1530	=item IO::AIO::min_parallel $nthreads	2021	=item IO::AIO::min_parallel $nthreads
…		…
1591	longer exceeded.	2082	longer exceeded.
1592		2083
1593	In other words, this setting does not enforce a queue limit, but can be	2084	In other words, this setting does not enforce a queue limit, but can be
1594	used to make poll functions block if the limit is exceeded.	2085	used to make poll functions block if the limit is exceeded.
1595		2086
1596	This is a very bad function to use in interactive programs because it	2087	This is a bad function to use in interactive programs because it blocks,
1597	blocks, and a bad way to reduce concurrency because it is inexact: Better	2088	and a bad way to reduce concurrency because it is inexact. If you need to
		2089	issue many requests without being able to call a poll function on demand,
1598	use an C<aio_group> together with a feed callback.	2090	it is better to use an C<aio_group> together with a feed callback.
1599		2091
1600	It's main use is in scripts without an event loop - when you want to stat	2092	Its main use is in scripts without an event loop - when you want to stat a
1601	a lot of files, you can write somehting like this:	2093	lot of files, you can write something like this:
1602		2094
1603	IO::AIO::max_outstanding 32;	2095	IO::AIO::max_outstanding 32;
1604		2096
1605	for my $path (...) {	2097	for my $path (...) {
1606	aio_stat $path , ...;	2098	aio_stat $path , ...;
1607	IO::AIO::poll_cb;	2099	IO::AIO::poll_cb;
1608	}	2100	}
1609		2101
1610	IO::AIO::flush;	2102	IO::AIO::flush;
1611		2103
1612	The call to C<poll_cb> inside the loop will normally return instantly, but	2104	The call to C<poll_cb> inside the loop will normally return instantly,
1613	as soon as more thna C<32> reqeusts are in-flight, it will block until	2105	allowing the loop to progress, but as soon as more than C<32> requests
1614	some requests have been handled. This keeps the loop from pushing a large	2106	are in-flight, it will block until some requests have been handled. This
1615	number of C<aio_stat> requests onto the queue.	2107	keeps the loop from pushing a large number of C<aio_stat> requests onto
		2108	the queue (which, with many paths to stat, can use up a lot of memory).
1616		2109
1617	The default value for C<max_outstanding> is very large, so there is no	2110	The default value for C<max_outstanding> is very large, so there is no
1618	practical limit on the number of outstanding requests.	2111	practical limit on the number of outstanding requests.
1619		2112
1620	=back	2113	=back
1621		2114
		2115
1622	=head3 STATISTICAL INFORMATION	2116	=head3 STATISTICAL INFORMATION
1623		2117
1624	=over	2118	=over
1625		2119
1626	=item IO::AIO::nreqs	2120	=item IO::AIO::nreqs
…		…
1643	Returns the number of requests currently in the pending state (executed,	2137	Returns the number of requests currently in the pending state (executed,
1644	but not yet processed by poll_cb).	2138	but not yet processed by poll_cb).
1645		2139
1646	=back	2140	=back
1647		2141
		2142
		2143	=head3 SUBSECOND STAT TIME ACCESS
		2144
		2145	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2146	generally find access/modification and change times with subsecond time
		2147	accuracy of the system supports it, but perl's built-in functions only
		2148	return the integer part.
		2149
		2150	The following functions return the timestamps of the most recent
		2151	stat with subsecond precision on most systems and work both after
		2152	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2153	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2154	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2155
		2156	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2157	full resolution without rounding and work with standard perl C<stat>,
		2158	alleviating the need to call the special C<Time::HiRes> functions, which
		2159	do not act like their perl counterparts.
		2160
		2161	On operating systems or file systems where subsecond time resolution is
		2162	not supported or could not be detected, a fractional part of C<0> is
		2163	returned, so it is always safe to call these functions.
		2164
		2165	=over 4
		2166
		2167	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		2168
		2169	Return the access, modication, change or birth time, respectively,
		2170	including fractional part. Due to the limited precision of floating point,
		2171	the accuracy on most platforms is only a bit better than milliseconds
		2172	for times around now - see the I<nsec> function family, below, for full
		2173	accuracy.
		2174
		2175	File birth time is only available when the OS and perl support it (on
		2176	FreeBSD and NetBSD at the time of this writing, although support is
		2177	adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
		2178	it). On systems where it isn't available, C<0> is currently returned, but
		2179	this might change to C<undef> in a future version.
		2180
		2181	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		2182
		2183	Returns access, modification, change and birth time all in one go, and
		2184	maybe more times in the future version.
		2185
		2186	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		2187
		2188	Return the fractional access, modifcation, change or birth time, in nanoseconds,
		2189	as an integer in the range C<0> to C<999999999>.
		2190
		2191	Note that no accessors are provided for access, modification and
		2192	change times - you need to get those from C<stat _> if required (C<int
		2193	IO::AIO::st_atime> and so on will I<not> generally give you the correct
		2194	value).
		2195
		2196	=item $seconds = IO::AIO::st_btimesec
		2197
		2198	The (integral) seconds part of the file birth time, if available.
		2199
		2200	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		2201
		2202	Like the functions above, but returns all four times in one go (and maybe
		2203	more in future versions).
		2204
		2205	=item $counter = IO::AIO::st_gen
		2206
		2207	Returns the generation counter (in practice this is just a random number)
		2208	of the file. This is only available on platforms which have this member in
		2209	their C<struct stat> (most BSDs at the time of this writing) and generally
		2210	only to the root usert. If unsupported, C<0> is returned, but this might
		2211	change to C<undef> in a future version.
		2212
		2213	=back
		2214
		2215	Example: print the high resolution modification time of F</etc>, using
		2216	C<stat>, and C<IO::AIO::aio_stat>.
		2217
		2218	if (stat "/etc") {
		2219	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2220	}
		2221
		2222	IO::AIO::aio_stat "/etc", sub {
		2223	$_[0]
		2224	and return;
		2225
		2226	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2227	};
		2228
		2229	IO::AIO::flush;
		2230
		2231	Output of the awbove on my system, showing reduced and full accuracy:
		2232
		2233	stat(/etc) mtime: 1534043702.020808
		2234	aio_stat(/etc) mtime: 1534043702.020807792
		2235
		2236
1648	=head3 MISCELLANEOUS FUNCTIONS	2237	=head3 MISCELLANEOUS FUNCTIONS
1649		2238
1650	IO::AIO implements some functions that might be useful, but are not	2239	IO::AIO implements some functions that are useful when you want to use
1651	asynchronous.	2240	some "Advanced I/O" function not available to in Perl, without going the
		2241	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2242	counterpart.
1652		2243
1653	=over 4	2244	=over 4
		2245
		2246	=item $retval = IO::AIO::fexecve $fh, $argv, $envp
		2247
		2248	A more-or-less direct equivalent to the POSIX C<fexecve> functions, which
		2249	allows you to specify the program to be executed via a file descriptor (or
		2250	handle). Returns C<-1> and sets errno to C<ENOSYS> if not available.
		2251
		2252	=item $retval = IO::AIO::mount $special, $path, $fstype, $flags = 0, $data = undef
		2253
		2254	Calls the GNU/Linux mount syscall with the given arguments. All except
		2255	C<$flags> are strings, and if C<$data> is C<undef>, a C<NULL> will be
		2256	passed.
		2257
		2258	The following values for C<$flags> are available:
		2259
		2260	C<IO::AIO::MS_RDONLY>, C<IO::AIO::MS_NOSUID>, C<IO::AIO::MS_NODEV>, C<IO::AIO::MS_NOEXEC>, C<IO::AIO::MS_SYNCHRONOUS>,
		2261	C<IO::AIO::MS_REMOUNT>, C<IO::AIO::MS_MANDLOCK>, C<IO::AIO::MS_DIRSYNC>, C<IO::AIO::MS_NOATIME>,
		2262	C<IO::AIO::MS_NODIRATIME>, C<IO::AIO::MS_BIND>, C<IO::AIO::MS_MOVE>, C<IO::AIO::MS_REC>, C<IO::AIO::MS_SILENT>,
		2263	C<IO::AIO::MS_POSIXACL>, C<IO::AIO::MS_UNBINDABLE>, C<IO::AIO::MS_PRIVATE>, C<IO::AIO::MS_SLAVE>, C<IO::AIO::MS_SHARED>,
		2264	C<IO::AIO::MS_RELATIME>, C<IO::AIO::MS_KERNMOUNT>, C<IO::AIO::MS_I_VERSION>, C<IO::AIO::MS_STRICTATIME>,
		2265	C<IO::AIO::MS_LAZYTIME>, C<IO::AIO::MS_ACTIVE>, C<IO::AIO::MS_NOUSER>, C<IO::AIO::MS_RMT_MASK>, C<IO::AIO::MS_MGC_VAL> and
		2266	C<IO::AIO::MS_MGC_MSK>.
		2267
		2268	=item $retval = IO::AIO::umount $path, $flags = 0
		2269
		2270	Invokes the GNU/Linux C<umount> or C<umount2> syscalls. Always calls
		2271	C<umount> if C<$flags> is C<0>, otherwqise always tries to call
		2272	C<umount2>.
		2273
		2274	The following C<$flags> are available:
		2275
		2276	C<IO::AIO::MNT_FORCE>, C<IO::AIO::MNT_DETACH>, C<IO::AIO::MNT_EXPIRE> and C<IO::AIO::UMOUNT_NOFOLLOW>.
		2277
		2278	=item $numfd = IO::AIO::get_fdlimit
		2279
		2280	Tries to find the current file descriptor limit and returns it, or
		2281	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2282	the highest valid file descriptor number.
		2283
		2284	=item IO::AIO::min_fdlimit [$numfd]
		2285
		2286	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2287	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2288	is missing, it will try to set a very high limit, although this is not
		2289	recommended when you know the actual minimum that you require.
		2290
		2291	If the limit cannot be raised enough, the function makes a best-effort
		2292	attempt to increase the limit as much as possible, using various
		2293	tricks, while still failing. You can query the resulting limit using
		2294	C<IO::AIO::get_fdlimit>.
		2295
		2296	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2297	true.
1654		2298
1655	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2299	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1656		2300
1657	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2301	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1658	but is blocking (this makes most sense if you know the input data is	2302	but is blocking (this makes most sense if you know the input data is
…		…
1663		2307
1664	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2308	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1665		2309
1666	Simply calls the C<posix_fadvise> function (see its	2310	Simply calls the C<posix_fadvise> function (see its
1667	manpage for details). The following advice constants are	2311	manpage for details). The following advice constants are
1668	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2312	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1669	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2313	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1670	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2314	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1671		2315
1672	On systems that do not implement C<posix_fadvise>, this function returns	2316	On systems that do not implement C<posix_fadvise>, this function returns
1673	ENOSYS, otherwise the return value of C<posix_fadvise>.	2317	ENOSYS, otherwise the return value of C<posix_fadvise>.
1674		2318
1675	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2319	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1676		2320
1677	Simply calls the C<posix_madvise> function (see its	2321	Simply calls the C<posix_madvise> function (see its
1678	manpage for details). The following advice constants are	2322	manpage for details). The following advice constants are
1679	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2323	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1680	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2324	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2325	C<IO::AIO::MADV_DONTNEED>.
		2326
		2327	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2328	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2329	will be reduced to fit into the C<$scalar>.
1681		2330
1682	On systems that do not implement C<posix_madvise>, this function returns	2331	On systems that do not implement C<posix_madvise>, this function returns
1683	ENOSYS, otherwise the return value of C<posix_madvise>.	2332	ENOSYS, otherwise the return value of C<posix_madvise>.
1684		2333
1685	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2334	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1686		2335
1687	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2336	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1688	$scalar (see its manpage for details). The following protect	2337	$scalar (see its manpage for details). The following protect
1689	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2338	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1690	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2339	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2340
		2341	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2342	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2343	will be reduced to fit into the C<$scalar>.
1691		2344
1692	On systems that do not implement C<mprotect>, this function returns	2345	On systems that do not implement C<mprotect>, this function returns
1693	ENOSYS, otherwise the return value of C<mprotect>.	2346	ENOSYS, otherwise the return value of C<mprotect>.
1694		2347
1695	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2348	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1696		2349
1697	Memory-maps a file (or anonymous memory range) and attaches it to the	2350	Memory-maps a file (or anonymous memory range) and attaches it to the
1698	given C<$scalar>, which will act like a string scalar.	2351	given C<$scalar>, which will act like a string scalar. Returns true on
		2352	success, and false otherwise.
1699		2353
		2354	The scalar must exist, but its contents do not matter - this means you
		2355	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2356	the scalar first.
		2357
1700	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2358	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1701	change the string length, and most read-only operations such as copying it	2359	which don't change the string length, and most read-only operations such
1702	or searching it with regexes and so on.	2360	as copying it or searching it with regexes and so on.
1703		2361
1704	Anything else is unsafe and will, at best, result in memory leaks.	2362	Anything else is unsafe and will, at best, result in memory leaks.
1705		2363
1706	The memory map associated with the C<$scalar> is automatically removed	2364	The memory map associated with the C<$scalar> is automatically removed
1707	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2365	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1708	C<IO::AIO::munmap> functions are called.	2366	or C<IO::AIO::munmap> functions are called on it.
1709		2367
1710	This calls the C<mmap>(2) function internally. See your system's manual	2368	This calls the C<mmap>(2) function internally. See your system's manual
1711	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2369	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1712		2370
1713	The C<$length> must be larger than zero and smaller than the actual	2371	The C<$length> must be larger than zero and smaller than the actual
1714	filesize.	2372	filesize.
1715		2373
1716	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2374	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1717	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2375	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1718		2376
1719	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2377	C<$flags> can be a combination of
1720	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2378	C<IO::AIO::MAP_SHARED> or
1721	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2379	C<IO::AIO::MAP_PRIVATE>,
		2380	or a number of system-specific flags (when not available, the are C<0>):
1722	(which is set to C<MAP_ANON> if your system only provides this	2381	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1723	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2382	C<IO::AIO::MAP_LOCKED>,
1724	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2383	C<IO::AIO::MAP_NORESERVE>,
		2384	C<IO::AIO::MAP_POPULATE>,
1725	C<IO::AIO::MAP_NONBLOCK>	2385	C<IO::AIO::MAP_NONBLOCK>,
		2386	C<IO::AIO::MAP_FIXED>,
		2387	C<IO::AIO::MAP_GROWSDOWN>,
		2388	C<IO::AIO::MAP_32BIT>,
		2389	C<IO::AIO::MAP_HUGETLB>,
		2390	C<IO::AIO::MAP_STACK>,
		2391	C<IO::AIO::MAP_FIXED_NOREPLACE>,
		2392	C<IO::AIO::MAP_SHARED_VALIDATE>,
		2393	C<IO::AIO::MAP_SYNC> or
		2394	C<IO::AIO::MAP_UNINITIALIZED>.
1726		2395
1727	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2396	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1728		2397
1729	C<$offset> is the offset from the start of the file - it generally must be	2398	C<$offset> is the offset from the start of the file - it generally must be
1730	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2399	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1744		2413
1745	=item IO::AIO::munmap $scalar	2414	=item IO::AIO::munmap $scalar
1746		2415
1747	Removes a previous mmap and undefines the C<$scalar>.	2416	Removes a previous mmap and undefines the C<$scalar>.
1748		2417
		2418	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2419
		2420	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2421	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2422	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2423
		2424	Returns true if successful, and false otherwise. If the underlying mmapped
		2425	region has changed address, then the true value has the numerical value
		2426	C<1>, otherwise it has the numerical value C<0>:
		2427
		2428	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2429	or die "mremap: $!";
		2430
		2431	if ($success*1) {
		2432	warn "scalar has chanegd address in memory\n";
		2433	}
		2434
		2435	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2436	implemented, but not supported and might go away in a future version.
		2437
		2438	On systems where this call is not supported or is not emulated, this call
		2439	returns falls and sets C<$!> to C<ENOSYS>.
		2440
		2441	=item IO::AIO::mlockall $flags
		2442
		2443	Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
		2444	but is blocking.
		2445
1749	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef	2446	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1750		2447
1751	Calls the C<munlock> function, undoing the effects of a previous	2448	Calls the C<munlock> function, undoing the effects of a previous
1752	C<aio_mlock> call (see its description for details).	2449	C<aio_mlock> call (see its description for details).
1753		2450
…		…
1755		2452
1756	Calls the C<munlockall> function.	2453	Calls the C<munlockall> function.
1757		2454
1758	On systems that do not implement C<munlockall>, this function returns	2455	On systems that do not implement C<munlockall>, this function returns
1759	ENOSYS, otherwise the return value of C<munlockall>.	2456	ENOSYS, otherwise the return value of C<munlockall>.
		2457
		2458	=item $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		2459
		2460	Uses the GNU/Linux C<accept4(2)> syscall, if available, to accept a socket
		2461	and return the new file handle on success, or sets C<$!> and returns
		2462	C<undef> on error.
		2463
		2464	The remote name of the new socket will be stored in C<$sockaddr>, which
		2465	will be extended to allow for at least C<$sockaddr_maxlen> octets. If the
		2466	socket name does not fit into C<$sockaddr_maxlen> octets, this is signaled
		2467	by returning a longer string in C<$sockaddr>, which might or might not be
		2468	truncated.
		2469
		2470	To accept name-less sockets, use C<undef> for C<$sockaddr> and C<0> for
		2471	C<$sockaddr_maxlen>.
		2472
		2473	The main reasons to use this syscall rather than portable C<accept(2)>
		2474	are that you can specify C<SOCK_NONBLOCK> and/or C<SOCK_CLOEXEC>
		2475	flags and you can accept name-less sockets by specifying C<0> for
		2476	C<$sockaddr_maxlen>, which is sadly not possible with perl's interface to
		2477	C<accept>.
		2478
		2479	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2480
		2481	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2482	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2483	should be the file offset.
		2484
		2485	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2486	silently corrupt the data in this case.
		2487
		2488	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2489	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2490	C<IO::AIO::SPLICE_F_GIFT>.
		2491
		2492	See the C<splice(2)> manpage for details.
		2493
		2494	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2495
		2496	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2497	description for C<IO::AIO::splice> above for details.
		2498
		2499	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2500
		2501	Attempts to query or change the pipe buffer size. Obviously works only
		2502	on pipes, and currently works only on GNU/Linux systems, and fails with
		2503	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2504	size on other systems, drop me a note.
		2505
		2506	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2507
		2508	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2509	C<$flags> is missing or C<0>, then this should be the same as a call to
		2510	perl's built-in C<pipe> function and create a new pipe, and works on
		2511	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2512	(..., 4096, O_BINARY)>.
		2513
		2514	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2515	the given flags (Linux 2.6.27, glibc 2.9).
		2516
		2517	On success, the read and write file handles are returned.
		2518
		2519	On error, nothing will be returned. If the pipe2 syscall is missing and
		2520	C<$flags> is non-zero, fails with C<ENOSYS>.
		2521
		2522	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2523	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2524	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2525
		2526	Example: create a pipe race-free w.r.t. threads and fork:
		2527
		2528	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2529	or die "pipe2: $!\n";
		2530
		2531	=item $fh = IO::AIO::memfd_create $pathname[, $flags]
		2532
		2533	This is a direct interface to the Linux L<memfd_create(2)> system
		2534	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2535	should be C<IO::AIO::MFD_CLOEXEC>.
		2536
		2537	On success, the new memfd filehandle is returned, otherwise returns
		2538	C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
		2539
		2540	Please refer to L<memfd_create(2)> for more info on this call.
		2541
		2542	The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
		2543	C<IO::AIO::MFD_ALLOW_SEALING>, C<IO::AIO::MFD_HUGETLB>,
		2544	C<IO::AIO::MFD_HUGETLB_2MB> and C<IO::AIO::MFD_HUGETLB_1GB>.
		2545
		2546	Example: create a new memfd.
		2547
		2548	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2549	or die "memfd_create: $!\n";
		2550
		2551	=item $fh = IO::AIO::pidfd_open $pid[, $flags]
		2552
		2553	This is an interface to the Linux L<pidfd_open(2)> system call. The
		2554	default for C<$flags> is C<0>.
		2555
		2556	On success, a new pidfd filehandle is returned (that is already set to
		2557	close-on-exec), otherwise returns C<undef>. If the syscall is missing,
		2558	fails with C<ENOSYS>.
		2559
		2560	Example: open pid 6341 as pidfd.
		2561
		2562	my $fh = IO::AIO::pidfd_open 6341
		2563	or die "pidfd_open: $!\n";
		2564
		2565	=item $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		2566
		2567	This is an interface to the Linux L<pidfd_send_signal> system call. The
		2568	default for C<$siginfo> is C<undef> and the default for C<$flags> is C<0>.
		2569
		2570	Returns the system call status. If the syscall is missing, fails with
		2571	C<ENOSYS>.
		2572
		2573	When specified, C<$siginfo> must be a reference to a hash with one or more
		2574	of the following members:
		2575
		2576	=over
		2577
		2578	=item code - the C<si_code> member
		2579
		2580	=item pid - the C<si_pid> member
		2581
		2582	=item uid - the C<si_uid> member
		2583
		2584	=item value_int - the C<si_value.sival_int> member
		2585
		2586	=item value_ptr - the C<si_value.sival_ptr> member, specified as an integer
		2587
		2588	=back
		2589
		2590	Example: send a SIGKILL to the specified process.
		2591
		2592	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
		2593	and die "pidfd_send_signal: $!\n";
		2594
		2595	Example: send a SIGKILL to the specified process with extra data.
		2596
		2597	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
		2598	and die "pidfd_send_signal: $!\n";
		2599
		2600	=item $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		2601
		2602	This is an interface to the Linux L<pidfd_getfd> system call. The default
		2603	for C<$flags> is C<0>.
		2604
		2605	On success, returns a dup'ed copy of the target file descriptor (specified
		2606	as an integer) returned (that is already set to close-on-exec), otherwise
		2607	returns C<undef>. If the syscall is missing, fails with C<ENOSYS>.
		2608
		2609	Example: get a copy of standard error of another process and print soemthing to it.
		2610
		2611	my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
		2612	or die "pidfd_getfd: $!\n";
		2613	print $errfh "stderr\n";
		2614
		2615	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2616
		2617	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2618	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2619
		2620	On success, the new eventfd filehandle is returned, otherwise returns
		2621	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2622
		2623	Please refer to L<eventfd(2)> for more info on this call.
		2624
		2625	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2626	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2627
		2628	Example: create a new eventfd filehandle:
		2629
		2630	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2631	or die "eventfd: $!\n";
		2632
		2633	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2634
		2635	This is a direct interface to the Linux L<timerfd_create(2)> system
		2636	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2637	should be C<IO::AIO::TFD_CLOEXEC>.
		2638
		2639	On success, the new timerfd filehandle is returned, otherwise returns
		2640	C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
		2641
		2642	Please refer to L<timerfd_create(2)> for more info on this call.
		2643
		2644	The following C<$clockid> values are
		2645	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2646	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2647	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2648	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2649
		2650	The following C<$flags> values are available (Linux
		2651	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2652
		2653	Example: create a new timerfd and set it to one-second repeated alarms,
		2654	then wait for two alarms:
		2655
		2656	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2657	or die "timerfd_create: $!\n";
		2658
		2659	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2660	or die "timerfd_settime: $!\n";
		2661
		2662	for (1..2) {
		2663	8 == sysread $fh, my $buf, 8
		2664	or die "timerfd read failure\n";
		2665
		2666	printf "number of expirations (likely 1): %d\n",
		2667	unpack "Q", $buf;
		2668	}
		2669
		2670	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2671
		2672	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2673	call. Please refer to its manpage for more info on this call.
		2674
		2675	The new itimerspec is specified using two (possibly fractional) second
		2676	values, C<$new_interval> and C<$new_value>).
		2677
		2678	On success, the current interval and value are returned (as per
		2679	C<timerfd_gettime>). On failure, the empty list is returned.
		2680
		2681	The following C<$flags> values are
		2682	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2683	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2684
		2685	See C<IO::AIO::timerfd_create> for a full example.
		2686
		2687	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2688
		2689	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2690	call. Please refer to its manpage for more info on this call.
		2691
		2692	On success, returns the current values of interval and value for the given
		2693	timerfd (as potentially fractional second values). On failure, the empty
		2694	list is returned.
1760		2695
1761	=back	2696	=back
1762		2697
1763	=cut	2698	=cut
1764		2699
…		…
1802	=head2 FORK BEHAVIOUR	2737	=head2 FORK BEHAVIOUR
1803		2738
1804	Usage of pthreads in a program changes the semantics of fork	2739	Usage of pthreads in a program changes the semantics of fork
1805	considerably. Specifically, only async-safe functions can be called after	2740	considerably. Specifically, only async-safe functions can be called after
1806	fork. Perl doesn't know about this, so in general, you cannot call fork	2741	fork. Perl doesn't know about this, so in general, you cannot call fork
1807	with defined behaviour in perl. IO::AIO uses pthreads, so this applies,	2742	with defined behaviour in perl if pthreads are involved. IO::AIO uses
1808	but many other extensions and (for inexplicable reasons) perl itself often	2743	pthreads, so this applies, but many other extensions and (for inexplicable
1809	is linked against pthreads, so this limitation applies.	2744	reasons) perl itself often is linked against pthreads, so this limitation
		2745	applies to quite a lot of perls.
1810		2746
1811	Some operating systems have extensions that allow safe use of fork, and	2747	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1812	this module should do "the right thing" on those, and tries on others. At	2748	only works in the process that loaded it. Forking is fully supported, but
1813	the time of this writing (2011) only GNU/Linux supports these extensions	2749	using IO::AIO in the child is not.
1814	to POSIX.	2750
		2751	You might get around by not I<using> IO::AIO before (or after)
		2752	forking. You could also try to call the L<IO::AIO::reinit> function in the
		2753	child:
		2754
		2755	=over 4
		2756
		2757	=item IO::AIO::reinit
		2758
		2759	Abandons all current requests and I/O threads and simply reinitialises all
		2760	data structures. This is not an operation supported by any standards, but
		2761	happens to work on GNU/Linux and some newer BSD systems.
		2762
		2763	The only reasonable use for this function is to call it after forking, if
		2764	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2765	the process will result in undefined behaviour. Calling it at any time
		2766	will also result in any undefined (by POSIX) behaviour.
		2767
		2768	=back
		2769
		2770	=head2 LINUX-SPECIFIC CALLS
		2771
		2772	When a call is documented as "linux-specific" then this means it
		2773	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2774	availability and compatibility of such calls regardless of the platform
		2775	it is compiled on, so platforms such as FreeBSD which often implement
		2776	these calls will work. When in doubt, call them and see if they fail wth
		2777	C<ENOSYS>.
1815		2778
1816	=head2 MEMORY USAGE	2779	=head2 MEMORY USAGE
1817		2780
1818	Per-request usage:	2781	Per-request usage:
1819		2782
…		…
1832	temporary buffers, and each thread requires a stack and other data	2795	temporary buffers, and each thread requires a stack and other data
1833	structures (usually around 16k-128k, depending on the OS).	2796	structures (usually around 16k-128k, depending on the OS).
1834		2797
1835	=head1 KNOWN BUGS	2798	=head1 KNOWN BUGS
1836		2799
1837	Known bugs will be fixed in the next release.	2800	Known bugs will be fixed in the next release :)
		2801
		2802	=head1 KNOWN ISSUES
		2803
		2804	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2805	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2806	non-created hash slots or other scalars I didn't think of. It's best to
		2807	avoid such and either use scalar variables or making sure that the scalar
		2808	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2809
		2810	I am not sure anything can be done about this, so this is considered a
		2811	known issue, rather than a bug.
1838		2812
1839	=head1 SEE ALSO	2813	=head1 SEE ALSO
1840		2814
1841	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2815	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1842	more natural syntax.	2816	more natural syntax and L<IO::FDPass> for file descriptor passing.
1843		2817
1844	=head1 AUTHOR	2818	=head1 AUTHOR
1845		2819
1846	Marc Lehmann <schmorp@schmorp.de>	2820	Marc Lehmann <schmorp@schmorp.de>
1847	http://home.schmorp.de/	2821	http://home.schmorp.de/

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