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Revision 1.181 by root, Tue May 4 21:14:01 2010 UTC vs.
Revision 1.320 by root, Tue Feb 20 06:40:23 2024 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 = '3.65';	176	our $VERSION = 4.81;
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_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_statvfs);	186	aio_msync aio_mtouch aio_mlock aio_mlockall
		187	aio_statvfs
		188	aio_slurp
		189	aio_wd);
183		190
184	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	191	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
185	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	192	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
186	min_parallel max_parallel max_idle	193	min_parallel max_parallel max_idle idle_timeout
187	nreqs nready npending nthreads	194	nreqs nready npending nthreads
188	max_poll_time max_poll_reqs	195	max_poll_time max_poll_reqs
189	sendfile fadvise);	196	sendfile fadvise madvise
		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);
190		203
191	push @AIO_REQ, qw(aio_busy); # not exported	204	push @AIO_REQ, qw(aio_busy); # not exported
192		205
193	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	206	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
194		207
…		…
198		211
199	=head1 FUNCTIONS	212	=head1 FUNCTIONS
200		213
201	=head2 QUICK OVERVIEW	214	=head2 QUICK OVERVIEW
202		215
203	This section simply lists the prototypes of the most important functions	216	This section simply lists the prototypes most of the functions for
204	for quick reference. See the following sections for function-by-function	217	quick reference. See the following sections for function-by-function
205	documentation.	218	documentation.
206		219
		220	aio_wd $pathname, $callback->($wd)
207	aio_open $pathname, $flags, $mode, $callback->($fh)	221	aio_open $pathname, $flags, $mode, $callback->($fh)
208	aio_close $fh, $callback->($status)	222	aio_close $fh, $callback->($status)
		223	aio_seek $fh,$offset,$whence, $callback->($offs)
209	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	224	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
210	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	225	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
211	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	226	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
212	aio_readahead $fh,$offset,$length, $callback->($retval)	227	aio_readahead $fh,$offset,$length, $callback->($retval)
213	aio_stat $fh_or_path, $callback->($status)	228	aio_stat $fh_or_path, $callback->($status)
214	aio_lstat $fh, $callback->($status)	229	aio_lstat $fh, $callback->($status)
215	aio_statvfs $fh_or_path, $callback->($statvfs)	230	aio_statvfs $fh_or_path, $callback->($statvfs)
216	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	231	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
217	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)
218	aio_truncate $fh_or_path, $offset, $callback->($status)	234	aio_truncate $fh_or_path, $offset, $callback->($status)
219	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)
220	aio_unlink $pathname, $callback->($status)	237	aio_unlink $pathname, $callback->($status)
221	aio_mknod $path, $mode, $dev, $callback->($status)	238	aio_mknod $pathname, $mode, $dev, $callback->($status)
222	aio_link $srcpath, $dstpath, $callback->($status)	239	aio_link $srcpath, $dstpath, $callback->($status)
223	aio_symlink $srcpath, $dstpath, $callback->($status)	240	aio_symlink $srcpath, $dstpath, $callback->($status)
224	aio_readlink $path, $callback->($link)	241	aio_readlink $pathname, $callback->($link)
		242	aio_realpath $pathname, $callback->($path)
225	aio_rename $srcpath, $dstpath, $callback->($status)	243	aio_rename $srcpath, $dstpath, $callback->($status)
		244	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
226	aio_mkdir $pathname, $mode, $callback->($status)	245	aio_mkdir $pathname, $mode, $callback->($status)
227	aio_rmdir $pathname, $callback->($status)	246	aio_rmdir $pathname, $callback->($status)
228	aio_readdir $pathname, $callback->($entries)	247	aio_readdir $pathname, $callback->($entries)
229	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	248	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
230	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	249	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
231	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)
232	aio_load $path, $data, $callback->($status)	252	aio_load $pathname, $data, $callback->($status)
233	aio_copy $srcpath, $dstpath, $callback->($status)	253	aio_copy $srcpath, $dstpath, $callback->($status)
234	aio_move $srcpath, $dstpath, $callback->($status)	254	aio_move $srcpath, $dstpath, $callback->($status)
235	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
236	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)
237	aio_sync $callback->($status)	258	aio_sync $callback->($status)
		259	aio_syncfs $fh, $callback->($status)
238	aio_fsync $fh, $callback->($status)	260	aio_fsync $fh, $callback->($status)
239	aio_fdatasync $fh, $callback->($status)	261	aio_fdatasync $fh, $callback->($status)
240	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	262	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
241	aio_pathsync $path, $callback->($status)	263	aio_pathsync $pathname, $callback->($status)
242	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	264	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
243	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	265	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		266	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		267	aio_mlockall $flags, $callback->($status)
244	aio_group $callback->(...)	268	aio_group $callback->(...)
245	aio_nop $callback->()	269	aio_nop $callback->()
246		270
247	$prev_pri = aioreq_pri [$pri]	271	$prev_pri = aioreq_pri [$pri]
248	aioreq_nice $pri_adjust	272	aioreq_nice $pri_adjust
…		…
254	IO::AIO::max_poll_reqs $nreqs	278	IO::AIO::max_poll_reqs $nreqs
255	IO::AIO::max_poll_time $seconds	279	IO::AIO::max_poll_time $seconds
256	IO::AIO::min_parallel $nthreads	280	IO::AIO::min_parallel $nthreads
257	IO::AIO::max_parallel $nthreads	281	IO::AIO::max_parallel $nthreads
258	IO::AIO::max_idle $nthreads	282	IO::AIO::max_idle $nthreads
		283	IO::AIO::idle_timeout $seconds
259	IO::AIO::max_outstanding $maxreqs	284	IO::AIO::max_outstanding $maxreqs
260	IO::AIO::nreqs	285	IO::AIO::nreqs
261	IO::AIO::nready	286	IO::AIO::nready
262	IO::AIO::npending	287	IO::AIO::npending
		288	IO::AIO::reinit
		289
		290	$nfd = IO::AIO::get_fdlimit
		291	IO::AIO::min_fdlimit $nfd
263		292
264	IO::AIO::sendfile $ofh, $ifh, $offset, $count	293	IO::AIO::sendfile $ofh, $ifh, $offset, $count
265	IO::AIO::fadvise $fh, $offset, $len, $advice	294	IO::AIO::fadvise $fh, $offset, $len, $advice
266	IO::AIO::mlockall $flags	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]
		300	IO::AIO::madvise $scalar, $offset, $length, $advice
		301	IO::AIO::mprotect $scalar, $offset, $length, $protect
		302	IO::AIO::munlock $scalar, $offset = 0, $length = undef
267	IO::AIO::munlockall	303	IO::AIO::munlockall
268		304
269	=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, $flags = 0
		334
		335	=head2 API NOTES
270		336
271	All the C<aio_*> calls are more or less thin wrappers around the syscall	337	All the C<aio_*> calls are more or less thin wrappers around the syscall
272	with the same name (sans C<aio_>). The arguments are similar or identical,	338	with the same name (sans C<aio_>). The arguments are similar or identical,
273	and they all accept an additional (and optional) C<$callback> argument	339	and they all accept an additional (and optional) C<$callback> argument
274	which must be a code reference. This code reference will get called with	340	which must be a code reference. This code reference will be called after
275	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	341	the syscall has been executed in an asynchronous fashion. The results
276	perl, which usually delivers "false") as its sole argument after the given	342	of the request will be passed as arguments to the callback (and, if an
277	syscall has been executed asynchronously.	343	error occured, in C<$!>) - 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>.
278		349
279	All functions expecting a filehandle keep a copy of the filehandle	350	All functions expecting a filehandle keep a copy of the filehandle
280	internally until the request has finished.	351	internally until the request has finished.
281		352
282	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
283	further manipulation of those requests while they are in-flight.	354	further manipulation of those requests while they are in-flight.
284		355
285	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
286	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
287	request is being executed, the current working directory could have	358	current working directory could have changed. Alternatively, you can
288	changed. Alternatively, you can make sure that you never change the	359	make sure that you never change the current working directory anywhere
289	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
290	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.
291		364
292	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
293	in filenames you got from outside (command line, readdir etc.) without	366	in filenames you got from outside (command line, readdir etc.) without
294	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
295	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
296	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
297	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.
298		372
299	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
300	handles correctly whether it is set or not.	374	handles correctly whether it is set or not.
		375
		376	=head2 AIO REQUEST FUNCTIONS
301		377
302	=over 4	378	=over 4
303		379
304	=item $prev_pri = aioreq_pri [$pri]	380	=item $prev_pri = aioreq_pri [$pri]
305		381
…		…
335		411
336		412
337	=item aio_open $pathname, $flags, $mode, $callback->($fh)	413	=item aio_open $pathname, $flags, $mode, $callback->($fh)
338		414
339	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
340	created filehandle for the file.	416	created filehandle for the file (or C<undef> in case of an error).
341
342	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
343	for an explanation.
344		417
345	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	418	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
346	list. They are the same as used by C<sysopen>.	419	list. They are the same as used by C<sysopen>.
347		420
348	Likewise, C<$mode> specifies the mode of the newly created file, if it	421	Likewise, C<$mode> specifies the mode of the newly created file, if it
…		…
361	} else {	434	} else {
362	die "open failed: $!\n";	435	die "open failed: $!\n";
363	}	436	}
364	};	437	};
365		438
		439	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		440	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		441	following POSIX and non-POSIX constants are available (missing ones on
		442	your system are, as usual, C<0>):
		443
		444	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		445	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		446	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
		447
366		448
367	=item aio_close $fh, $callback->($status)	449	=item aio_close $fh, $callback->($status)
368		450
369	Asynchronously close a file and call the callback with the result	451	Asynchronously close a file and call the callback with the result
370	code.	452	code.
…		…
379	Or in other words: the file descriptor will be closed, but it will not be	461	Or in other words: the file descriptor will be closed, but it will not be
380	free for reuse until the perl filehandle is closed.	462	free for reuse until the perl filehandle is closed.
381		463
382	=cut	464	=cut
383		465
		466	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		467
		468	Seeks the filehandle to the new C<$offset>, similarly to perl's
		469	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		470	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		471	C<IO::AIO::SEEK_END>).
		472
		473	The resulting absolute offset will be passed to the callback, or C<-1> in
		474	case of an error.
		475
		476	In theory, the C<$whence> constants could be different than the
		477	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		478	so don't panic.
		479
		480	As a GNU/Linux (and maybe Solaris) extension, also the constants
		481	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		482	could be found. No guarantees about suitability for use in C<aio_seek> or
		483	Perl's C<sysseek> can be made though, although I would naively assume they
		484	"just work".
		485
384	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	486	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
385		487
386	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	488	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
387		489
388	Reads or writes C<$length> bytes from or to the specified C<$fh> and	490	Reads or writes C<$length> bytes from or to the specified C<$fh> and
389	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	491	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
390	and calls the callback without the actual number of bytes read (or -1 on	492	calls the callback with the actual number of bytes transferred (or -1 on
391	error, just like the syscall).	493	error, just like the syscall).
392		494
393	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	495	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
394	offset plus the actual number of bytes read.	496	offset plus the actual number of bytes read.
395		497
…		…
420		522
421	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	523	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
422	reading at byte offset C<$in_offset>, and starts writing at the current	524	reading at byte offset C<$in_offset>, and starts writing at the current
423	file offset of C<$out_fh>. Because of that, it is not safe to issue more	525	file offset of C<$out_fh>. Because of that, it is not safe to issue more
424	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	526	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
425	other.	527	other. The same C<$in_fh> works fine though, as this function does not
		528	move or use the file offset of C<$in_fh>.
426		529
		530	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		531	are written, and there is no way to find out how many more bytes have been
		532	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		533	number of bytes written to C<$out_fh>. Only if the result value equals
		534	C<$length> one can assume that C<$length> bytes have been read.
		535
		536	Unlike with other C<aio_> functions, it makes a lot of sense to use
		537	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		538	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		539	the socket I/O will be non-blocking. Note, however, that you can run
		540	into a trap where C<aio_sendfile> reads some data with readahead, then
		541	fails to write all data, and when the socket is ready the next time, the
		542	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		543	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		544	resource usage.
		545
427	This call tries to make use of a native C<sendfile> syscall to provide	546	This call tries to make use of a native C<sendfile>-like syscall to
428	zero-copy operation. For this to work, C<$out_fh> should refer to a	547	provide zero-copy operation. For this to work, C<$out_fh> should refer to
429	socket, and C<$in_fh> should refer to an mmap'able file.	548	a socket, and C<$in_fh> should refer to an mmap'able file.
430		549
431	If a native sendfile cannot be found or it fails with C<ENOSYS>,	550	If a native sendfile cannot be found or it fails with C<ENOSYS>,
432	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,	551	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
433	it will be emulated, so you can call C<aio_sendfile> on any type of	552	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
434	filehandle regardless of the limitations of the operating system.	553	type of filehandle regardless of the limitations of the operating system.
435		554
436	Please note, however, that C<aio_sendfile> can read more bytes from	555	As native sendfile syscalls (as practically any non-POSIX interface hacked
437	C<$in_fh> than are written, and there is no way to find out how many	556	together in a hurry to improve benchmark numbers) tend to be rather buggy
438	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	557	on many systems, this implementation tries to work around some known bugs
439	provides the number of bytes written to C<$out_fh>. Only if the result	558	in Linux and FreeBSD kernels (probably others, too), but that might fail,
440	value equals C<$length> one can assume that C<$length> bytes have been	559	so you really really should check the return value of C<aio_sendfile> -
441	read.	560	fewer bytes than expected might have been transferred.
442		561
443		562
444	=item aio_readahead $fh,$offset,$length, $callback->($retval)	563	=item aio_readahead $fh,$offset,$length, $callback->($retval)
445		564
446	C<aio_readahead> populates the page cache with data from a file so that	565	C<aio_readahead> populates the page cache with data from a file so that
…		…
450	whole pages, so that offset is effectively rounded down to a page boundary	569	whole pages, so that offset is effectively rounded down to a page boundary
451	and bytes are read up to the next page boundary greater than or equal to	570	and bytes are read up to the next page boundary greater than or equal to
452	(off-set+length). C<aio_readahead> does not read beyond the end of the	571	(off-set+length). C<aio_readahead> does not read beyond the end of the
453	file. The current file offset of the file is left unchanged.	572	file. The current file offset of the file is left unchanged.
454		573
455	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	574	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
456	emulated by simply reading the data, which would have a similar effect.	575	be emulated by simply reading the data, which would have a similar effect.
457		576
458		577
459	=item aio_stat $fh_or_path, $callback->($status)	578	=item aio_stat $fh_or_path, $callback->($status)
460		579
461	=item aio_lstat $fh, $callback->($status)	580	=item aio_lstat $fh, $callback->($status)
462		581
463	Works like perl's C<stat> or C<lstat> in void context. The callback will	582	Works almost exactly like perl's C<stat> or C<lstat> in void context. The
464	be called after the stat and the results will be available using C<stat _>	583	callback will be called after the stat and the results will be available
465	or C<-s _> etc...	584	using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
466		585	and C<-T>).
467	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
468	for an explanation.
469		586
470	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	587	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
471	error when stat'ing a large file, the results will be silently truncated	588	error when stat'ing a large file, the results will be silently truncated
472	unless perl itself is compiled with large file support.	589	unless perl itself is compiled with large file support.
		590
		591	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		592	following constants and functions (if not implemented, the constants will
		593	be C<0> and the functions will either C<croak> or fall back on traditional
		594	behaviour).
		595
		596	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		597	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		598	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		599
		600	To access higher resolution stat timestamps, see L<SUBSECOND STAT TIME
		601	ACCESS>.
473		602
474	Example: Print the length of F</etc/passwd>:	603	Example: Print the length of F</etc/passwd>:
475		604
476	aio_stat "/etc/passwd", sub {	605	aio_stat "/etc/passwd", sub {
477	$_[0] and die "stat failed: $!";	606	$_[0] and die "stat failed: $!";
…		…
521	namemax => 255,	650	namemax => 255,
522	frsize => 1024,	651	frsize => 1024,
523	fsid => 1810	652	fsid => 1810
524	}	653	}
525		654
526
527	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	655	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
528		656
529	Works like perl's C<utime> function (including the special case of $atime	657	Works like perl's C<utime> function (including the special case of $atime
530	and $mtime being undef). Fractional times are supported if the underlying	658	and $mtime being undef). Fractional times are supported if the underlying
531	syscalls support them.	659	syscalls support them.
532		660
533	When called with a pathname, uses utimes(2) if available, otherwise	661	When called with a pathname, uses utimensat(2) or utimes(2) if available,
534	utime(2). If called on a file descriptor, uses futimes(2) if available,	662	otherwise utime(2). If called on a file descriptor, uses futimens(2)
535	otherwise returns ENOSYS, so this is not portable.	663	or futimes(2) if available, otherwise returns ENOSYS, so this is not
		664	portable.
536		665
537	Examples:	666	Examples:
538		667
539	# set atime and mtime to current time (basically touch(1)):	668	# set atime and mtime to current time (basically touch(1)):
540	aio_utime "path", undef, undef;	669	aio_utime "path", undef, undef;
…		…
558	=item aio_truncate $fh_or_path, $offset, $callback->($status)	687	=item aio_truncate $fh_or_path, $offset, $callback->($status)
559		688
560	Works like truncate(2) or ftruncate(2).	689	Works like truncate(2) or ftruncate(2).
561		690
562		691
		692	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		693
		694	Allocates or frees disk space according to the C<$mode> argument. See the
		695	linux C<fallocate> documentation for details.
		696
		697	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		698	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		699	to deallocate a file range.
		700
		701	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		702	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		703	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		704	to unshare shared blocks (see your L<fallocate(2)> manpage).
		705
		706	The file system block size used by C<fallocate> is presumably the
		707	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		708	can dictate other limitations.
		709
		710	If C<fallocate> isn't available or cannot be emulated (currently no
		711	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		712
		713
563	=item aio_chmod $fh_or_path, $mode, $callback->($status)	714	=item aio_chmod $fh_or_path, $mode, $callback->($status)
564		715
565	Works like perl's C<chmod> function.	716	Works like perl's C<chmod> function.
566		717
567		718
…		…
569		720
570	Asynchronously unlink (delete) a file and call the callback with the	721	Asynchronously unlink (delete) a file and call the callback with the
571	result code.	722	result code.
572		723
573		724
574	=item aio_mknod $path, $mode, $dev, $callback->($status)	725	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
575		726
576	[EXPERIMENTAL]	727	[EXPERIMENTAL]
577		728
578	Asynchronously create a device node (or fifo). See mknod(2).	729	Asynchronously create a device node (or fifo). See mknod(2).
579		730
580	The only (POSIX-) portable way of calling this function is:	731	The only (POSIX-) portable way of calling this function is:
581		732
582	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	733	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
583		734
		735	See C<aio_stat> for info about some potentially helpful extra constants
		736	and functions.
584		737
585	=item aio_link $srcpath, $dstpath, $callback->($status)	738	=item aio_link $srcpath, $dstpath, $callback->($status)
586		739
587	Asynchronously create a new link to the existing object at C<$srcpath> at	740	Asynchronously create a new link to the existing object at C<$srcpath> at
588	the path C<$dstpath> and call the callback with the result code.	741	the path C<$dstpath> and call the callback with the result code.
…		…
592		745
593	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	746	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
594	the path C<$dstpath> and call the callback with the result code.	747	the path C<$dstpath> and call the callback with the result code.
595		748
596		749
597	=item aio_readlink $path, $callback->($link)	750	=item aio_readlink $pathname, $callback->($link)
598		751
599	Asynchronously read the symlink specified by C<$path> and pass it to	752	Asynchronously read the symlink specified by C<$path> and pass it to
600	the callback. If an error occurs, nothing or undef gets passed to the	753	the callback. If an error occurs, nothing or undef gets passed to the
601	callback.	754	callback.
602		755
603		756
		757	=item aio_realpath $pathname, $callback->($path)
		758
		759	Asynchronously make the path absolute and resolve any symlinks in
		760	C<$path>. The resulting path only consists of directories (same as
		761	L<Cwd::realpath>).
		762
		763	This request can be used to get the absolute path of the current working
		764	directory by passing it a path of F<.> (a single dot).
		765
		766
604	=item aio_rename $srcpath, $dstpath, $callback->($status)	767	=item aio_rename $srcpath, $dstpath, $callback->($status)
605		768
606	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	769	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
607	rename(2) and call the callback with the result code.	770	rename(2) and call the callback with the result code.
		771
		772	On systems that support the AIO::WD working directory abstraction
		773	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		774	of failing, C<rename> is called on the absolute path of C<$wd>.
		775
		776
		777	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		778
		779	Basically a version of C<aio_rename> with an additional C<$flags>
		780	argument. Calling this with C<$flags=0> is the same as calling
		781	C<aio_rename>.
		782
		783	Non-zero flags are currently only supported on GNU/Linux systems that
		784	support renameat2. Other systems fail with C<ENOSYS> in this case.
		785
		786	The following constants are available (missing ones are, as usual C<0>),
		787	see renameat2(2) for details:
		788
		789	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		790	and C<IO::AIO::RENAME_WHITEOUT>.
608		791
609		792
610	=item aio_mkdir $pathname, $mode, $callback->($status)	793	=item aio_mkdir $pathname, $mode, $callback->($status)
611		794
612	Asynchronously mkdir (create) a directory and call the callback with	795	Asynchronously mkdir (create) a directory and call the callback with
…		…
617	=item aio_rmdir $pathname, $callback->($status)	800	=item aio_rmdir $pathname, $callback->($status)
618		801
619	Asynchronously rmdir (delete) a directory and call the callback with the	802	Asynchronously rmdir (delete) a directory and call the callback with the
620	result code.	803	result code.
621		804
		805	On systems that support the AIO::WD working directory abstraction
		806	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		807	C<rmdir> is called on the absolute path of C<$wd>.
		808
622		809
623	=item aio_readdir $pathname, $callback->($entries)	810	=item aio_readdir $pathname, $callback->($entries)
624		811
625	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	812	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
626	directory (i.e. opendir + readdir + closedir). The entries will not be	813	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
630	array-ref with the filenames.	817	array-ref with the filenames.
631		818
632		819
633	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	820	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
634		821
635	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	822	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
636	behaviour and output format. In case of an error, C<$entries> will be	823	tune behaviour and output format. In case of an error, C<$entries> will be
637	C<undef>.	824	C<undef>.
638		825
639	The flags are a combination of the following constants, ORed together (the	826	The flags are a combination of the following constants, ORed together (the
640	flags will also be passed to the callback, possibly modified):	827	flags will also be passed to the callback, possibly modified):
641		828
642	=over 4	829	=over 4
643		830
644	=item IO::AIO::READDIR_DENTS	831	=item IO::AIO::READDIR_DENTS
645		832
646	When this flag is off, then the callback gets an arrayref with of names	833	Normally the callback gets an arrayref consisting of names only (as
647	only (as with C<aio_readdir>), otherwise it gets an arrayref with	834	with C<aio_readdir>). If this flag is set, then the callback gets an
648	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	835	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
649	entry in more detail.	836	single directory entry in more detail:
650		837
651	C<$name> is the name of the entry.	838	C<$name> is the name of the entry.
652		839
653	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	840	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
654		841
655	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	842	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
656	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	843	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
657	C<IO::AIO::DT_WHT>.	844	C<IO::AIO::DT_WHT>.
658		845
659	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	846	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
660	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	847	to know, you have to run stat yourself. Also, for speed/memory reasons,
661	scalars are read-only: you can not modify them.	848	the C<$type> scalars are read-only: you must not modify them.
662		849
663	C<$inode> is the inode number (which might not be exact on systems with 64	850	C<$inode> is the inode number (which might not be exact on systems with 64
664	bit inode numbers and 32 bit perls). This field has unspecified content on	851	bit inode numbers and 32 bit perls). This field has unspecified content on
665	systems that do not deliver the inode information.	852	systems that do not deliver the inode information.
666		853
667	=item IO::AIO::READDIR_DIRS_FIRST	854	=item IO::AIO::READDIR_DIRS_FIRST
668		855
669	When this flag is set, then the names will be returned in an order where	856	When this flag is set, then the names will be returned in an order where
670	likely directories come first. This is useful when you need to quickly	857	likely directories come first, in optimal stat order. This is useful when
671	find directories, or you want to find all directories while avoiding to	858	you need to quickly find directories, or you want to find all directories
672	stat() each entry.	859	while avoiding to stat() each entry.
673		860
674	If the system returns type information in readdir, then this is used	861	If the system returns type information in readdir, then this is used
675	to find directories directly. Otherwise, likely directories are files	862	to find directories directly. Otherwise, likely directories are names
676	beginning with ".", or otherwise files with no dots, of which files with	863	beginning with ".", or otherwise names with no dots, of which names with
677	short names are tried first.	864	short names are tried first.
678		865
679	=item IO::AIO::READDIR_STAT_ORDER	866	=item IO::AIO::READDIR_STAT_ORDER
680		867
681	When this flag is set, then the names will be returned in an order	868	When this flag is set, then the names will be returned in an order
682	suitable for stat()'ing each one. That is, when you plan to stat()	869	suitable for stat()'ing each one. That is, when you plan to stat() most or
683	all files in the given directory, then the returned order will likely	870	all files in the given directory, then the returned order will likely be
684	be fastest.	871	faster.
685		872
686	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then	873	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
687	the likely dirs come first, resulting in a less optimal stat order.	874	then the likely dirs come first, resulting in a less optimal stat order
		875	for stat'ing all entries, but likely a more optimal order for finding
		876	subdirectories.
688		877
689	=item IO::AIO::READDIR_FOUND_UNKNOWN	878	=item IO::AIO::READDIR_FOUND_UNKNOWN
690		879
691	This flag should not be set when calling C<aio_readdirx>. Instead, it	880	This flag should not be set when calling C<aio_readdirx>. Instead, it
692	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	881	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
693	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	882	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
694	C<$type>'s are known, which can be used to speed up some algorithms.	883	C<$type>'s are known, which can be used to speed up some algorithms.
695		884
696	=back	885	=back
697		886
698		887
		888	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		889
		890	Opens, reads and closes the given file. The data is put into C<$data>,
		891	which is resized as required.
		892
		893	If C<$offset> is negative, then it is counted from the end of the file.
		894
		895	If C<$length> is zero, then the remaining length of the file is
		896	used. Also, in this case, the same limitations to modifying C<$data> apply
		897	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		898	with C<substr>. If the size of the file is known, specifying a non-zero
		899	C<$length> results in a performance advantage.
		900
		901	This request is similar to the older C<aio_load> request, but since it is
		902	a single request, it might be more efficient to use.
		903
		904	Example: load F</etc/passwd> into C<$passwd>.
		905
		906	my $passwd;
		907	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		908	$_[0] >= 0
		909	or die "/etc/passwd: $!\n";
		910
		911	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		912	print $passwd;
		913	};
		914	IO::AIO::flush;
		915
		916
699	=item aio_load $path, $data, $callback->($status)	917	=item aio_load $pathname, $data, $callback->($status)
700		918
701	This is a composite request that tries to fully load the given file into	919	This is a composite request that tries to fully load the given file into
702	memory. Status is the same as with aio_read.	920	memory. Status is the same as with aio_read.
		921
		922	Using C<aio_slurp> might be more efficient, as it is a single request.
703		923
704	=cut	924	=cut
705		925
706	sub aio_load($$;$) {	926	sub aio_load($$;$) {
707	my ($path, undef, $cb) = @_;	927	my ($path, undef, $cb) = @_;
…		…
728		948
729	Try to copy the I<file> (directories not supported as either source or	949	Try to copy the I<file> (directories not supported as either source or
730	destination) from C<$srcpath> to C<$dstpath> and call the callback with	950	destination) from C<$srcpath> to C<$dstpath> and call the callback with
731	a status of C<0> (ok) or C<-1> (error, see C<$!>).	951	a status of C<0> (ok) or C<-1> (error, see C<$!>).
732		952
		953	Existing destination files will be truncated.
		954
733	This is a composite request that creates the destination file with	955	This is a composite request that creates the destination file with
734	mode 0200 and copies the contents of the source file into it using	956	mode 0200 and copies the contents of the source file into it using
735	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	957	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
736	uid/gid, in that order.	958	uid/gid, in that order.
737		959
…		…
753	my @stat = stat $src_fh; # hmm, might block over nfs?	975	my @stat = stat $src_fh; # hmm, might block over nfs?
754		976
755	aioreq_pri $pri;	977	aioreq_pri $pri;
756	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	978	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
757	if (my $dst_fh = $_[0]) {	979	if (my $dst_fh = $_[0]) {
		980
		981	# best-effort preallocate
		982	aioreq_pri $pri;
		983	add $grp aio_allocate $dst_fh, IO::AIO::FALLOC_FL_KEEP_SIZE, 0, $stat[7], sub { };
		984
758	aioreq_pri $pri;	985	aioreq_pri $pri;
759	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	986	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
760	if ($_[0] == $stat[7]) {	987	if ($_[0] == $stat[7]) {
761	$grp->result (0);	988	$grp->result (0);
762	close $src_fh;	989	close $src_fh;
…		…
826	if ($_[0] && $! == EXDEV) {	1053	if ($_[0] && $! == EXDEV) {
827	aioreq_pri $pri;	1054	aioreq_pri $pri;
828	add $grp aio_copy $src, $dst, sub {	1055	add $grp aio_copy $src, $dst, sub {
829	$grp->result ($_[0]);	1056	$grp->result ($_[0]);
830		1057
831	if (!$_[0]) {	1058	unless ($_[0]) {
832	aioreq_pri $pri;	1059	aioreq_pri $pri;
833	add $grp aio_unlink $src;	1060	add $grp aio_unlink $src;
834	}	1061	}
835	};	1062	};
836	} else {	1063	} else {
…		…
839	};	1066	};
840		1067
841	$grp	1068	$grp
842	}	1069	}
843		1070
844	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1071	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
845		1072
846	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1073	Scans a directory (similar to C<aio_readdir>) but additionally tries to
847	efficiently separate the entries of directory C<$path> into two sets of	1074	efficiently separate the entries of directory C<$path> into two sets of
848	names, directories you can recurse into (directories), and ones you cannot	1075	names, directories you can recurse into (directories), and ones you cannot
849	recurse into (everything else, including symlinks to directories).	1076	recurse into (everything else, including symlinks to directories).
850		1077
851	C<aio_scandir> is a composite request that creates of many sub requests_	1078	C<aio_scandir> is a composite request that generates many sub requests.
852	C<$maxreq> specifies the maximum number of outstanding aio requests that	1079	C<$maxreq> specifies the maximum number of outstanding aio requests that
853	this function generates. If it is C<< <= 0 >>, then a suitable default	1080	this function generates. If it is C<< <= 0 >>, then a suitable default
854	will be chosen (currently 4).	1081	will be chosen (currently 4).
855		1082
856	On error, the callback is called without arguments, otherwise it receives	1083	On error, the callback is called without arguments, otherwise it receives
…		…
880	Then entries will be sorted into likely directories a non-initial dot	1107	Then entries will be sorted into likely directories a non-initial dot
881	currently) and likely non-directories (see C<aio_readdirx>). Then every	1108	currently) and likely non-directories (see C<aio_readdirx>). Then every
882	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1109	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
883	in order of their inode numbers. If that succeeds, it assumes that the	1110	in order of their inode numbers. If that succeeds, it assumes that the
884	entry is a directory or a symlink to directory (which will be checked	1111	entry is a directory or a symlink to directory (which will be checked
885	seperately). This is often faster than stat'ing the entry itself because	1112	separately). This is often faster than stat'ing the entry itself because
886	filesystems might detect the type of the entry without reading the inode	1113	filesystems might detect the type of the entry without reading the inode
887	data (e.g. ext2fs filetype feature), even on systems that cannot return	1114	data (e.g. ext2fs filetype feature), even on systems that cannot return
888	the filetype information on readdir.	1115	the filetype information on readdir.
889		1116
890	If the known number of directories (link count - 2) has been reached, the	1117	If the known number of directories (link count - 2) has been reached, the
…		…
906		1133
907	my $grp = aio_group $cb;	1134	my $grp = aio_group $cb;
908		1135
909	$maxreq = 4 if $maxreq <= 0;	1136	$maxreq = 4 if $maxreq <= 0;
910		1137
911	# stat once	1138	# get a wd object
912	aioreq_pri $pri;	1139	aioreq_pri $pri;
913	add $grp aio_stat $path, sub {	1140	add $grp aio_wd $path, sub {
		1141	$_[0]
914	return $grp->result () if $_[0];	1142	or return $grp->result ();
915	my $now = time;
916	my $hash1 = join ":", (stat _)[0,1,3,7,9];
917		1143
918	# read the directory entries	1144	my $wd = [shift, "."];
		1145
		1146	# stat once
919	aioreq_pri $pri;	1147	aioreq_pri $pri;
920	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1148	add $grp aio_stat $wd, sub {
921	my $entries = shift
922	or return $grp->result ();	1149	return $grp->result () if $_[0];
		1150	my $now = time;
		1151	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		1152	my $rdxflags = READDIR_DIRS_FIRST;
923		1153
924	# stat the dir another time	1154	if ((stat _)[3] < 2) {
		1155	# at least one non-POSIX filesystem exists
		1156	# that returns useful DT_type values: btrfs,
		1157	# so optimise for this here by requesting dents
		1158	$rdxflags |= READDIR_DENTS;
		1159	}
		1160
		1161	# read the directory entries
925	aioreq_pri $pri;	1162	aioreq_pri $pri;
926	add $grp aio_stat $path, sub {	1163	add $grp aio_readdirx $wd, $rdxflags, sub {
927	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1164	my ($entries, $flags) = @_
		1165	or return $grp->result ();
928		1166
		1167	if ($rdxflags & READDIR_DENTS) {
		1168	# if we requested type values, see if we can use them directly.
		1169
		1170	# if there were any DT_UNKNOWN entries then we assume we
		1171	# don't know. alternatively, we could assume that if we get
		1172	# one DT_DIR, then all directories are indeed marked with
		1173	# DT_DIR, but this seems not required for btrfs, and this
		1174	# is basically the "btrfs can't get it's act together" code
		1175	# branch.
		1176	unless ($flags & READDIR_FOUND_UNKNOWN) {
		1177	# now we have valid DT_ information for all entries,
		1178	# so use it as an optimisation without further stat's.
		1179	# they must also all be at the beginning of @$entries
		1180	# by now.
		1181
929	my $ndirs;	1182	my $dirs;
930		1183
931	# take the slow route if anything looks fishy
932	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
933	$ndirs = -1;
934	} else {
935	# if nlink == 2, we are finished
936	# for non-posix-fs's, we rely on nlink < 2
937	$ndirs = (stat _)[3] - 2
938	or return $grp->result ([], $entries);
939	}
940
941	my (@dirs, @nondirs);
942
943	my $statgrp = add $grp aio_group sub {
944	$grp->result (\@dirs, \@nondirs);
945	};
946
947	limit $statgrp $maxreq;
948	feed $statgrp sub {
949	return unless @$entries;
950	my $entry = shift @$entries;
951
952	aioreq_pri $pri;
953	add $statgrp aio_stat "$path/$entry/.", sub {
954	if ($_[0] < 0) {	1184	if (@$entries) {
955	push @nondirs, $entry;	1185	for (0 .. $#$entries) {
956	} else {	1186	if ($entries->[$_][1] != DT_DIR) {
957	# need to check for real directory	1187	# splice out directories
958	aioreq_pri $pri;	1188	$dirs = [splice @$entries, 0, $_];
959	add $statgrp aio_lstat "$path/$entry", sub {
960	if (-d _) {
961	push @dirs, $entry;
962
963	unless (--$ndirs) {
964	push @nondirs, @$entries;
965	feed $statgrp;
966	}	1189	last;
967	} else {
968	push @nondirs, $entry;
969	}	1190	}
970	}	1191	}
		1192
		1193	# if we didn't find any non-dir, then all entries are dirs
		1194	unless ($dirs) {
		1195	($dirs, $entries) = ($entries, []);
		1196	}
		1197	} else {
		1198	# directory is empty, so there are no sbdirs
		1199	$dirs = [];
971	}	1200	}
		1201
		1202	# either splice'd the directories out or the dir was empty.
		1203	# convert dents to filenames
		1204	$_ = $_->[0] for @$dirs;
		1205	$_ = $_->[0] for @$entries;
		1206
		1207	return $grp->result ($dirs, $entries);
		1208	}
		1209
		1210	# cannot use, so return to our old ways
		1211	# by pretending we only scanned for names.
		1212	$_ = $_->[0] for @$entries;
		1213	}
		1214
		1215	# stat the dir another time
		1216	aioreq_pri $pri;
		1217	add $grp aio_stat $wd, sub {
		1218	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		1219
		1220	my $ndirs;
		1221
		1222	# take the slow route if anything looks fishy
		1223	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
		1224	$ndirs = -1;
		1225	} else {
		1226	# if nlink == 2, we are finished
		1227	# for non-posix-fs's, we rely on nlink < 2
		1228	$ndirs = (stat _)[3] - 2
		1229	or return $grp->result ([], $entries);
		1230	}
		1231
		1232	my (@dirs, @nondirs);
		1233
		1234	my $statgrp = add $grp aio_group sub {
		1235	$grp->result (\@dirs, \@nondirs);
		1236	};
		1237
		1238	limit $statgrp $maxreq;
		1239	feed $statgrp sub {
		1240	return unless @$entries;
		1241	my $entry = shift @$entries;
		1242
		1243	aioreq_pri $pri;
		1244	$wd->[1] = "$entry/.";
		1245	add $statgrp aio_stat $wd, sub {
		1246	if ($_[0] < 0) {
		1247	push @nondirs, $entry;
		1248	} else {
		1249	# need to check for real directory
		1250	aioreq_pri $pri;
		1251	$wd->[1] = $entry;
		1252	add $statgrp aio_lstat $wd, sub {
		1253	if (-d _) {
		1254	push @dirs, $entry;
		1255
		1256	unless (--$ndirs) {
		1257	push @nondirs, @$entries;
		1258	feed $statgrp;
		1259	}
		1260	} else {
		1261	push @nondirs, $entry;
		1262	}
		1263	}
		1264	}
		1265	};
972	};	1266	};
973	};	1267	};
974	};	1268	};
975	};	1269	};
976	};	1270	};
977		1271
978	$grp	1272	$grp
979	}	1273	}
980		1274
981	=item aio_rmtree $path, $callback->($status)	1275	=item aio_rmtree $pathname, $callback->($status)
982		1276
983	Delete a directory tree starting (and including) C<$path>, return the	1277	Delete a directory tree starting (and including) C<$path>, return the
984	status of the final C<rmdir> only. This is a composite request that	1278	status of the final C<rmdir> only. This is a composite request that
985	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1279	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
986	everything else.	1280	everything else.
987		1281
988	=cut	1282	=cut
989		1283
…		…
1011	};	1305	};
1012		1306
1013	$grp	1307	$grp
1014	}	1308	}
1015		1309
		1310	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1311
		1312	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1313
		1314	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1315	they execute asynchronously and pass the return value to the callback.
		1316
		1317	Both calls can be used for a lot of things, some of which make more sense
		1318	to run asynchronously in their own thread, while some others make less
		1319	sense. For example, calls that block waiting for external events, such
		1320	as locking, will also lock down an I/O thread while it is waiting, which
		1321	can deadlock the whole I/O system. At the same time, there might be no
		1322	alternative to using a thread to wait.
		1323
		1324	So in general, you should only use these calls for things that do
		1325	(filesystem) I/O, not for things that wait for other events (network,
		1326	other processes), although if you are careful and know what you are doing,
		1327	you still can.
		1328
		1329	The following constants are available and can be used for normal C<ioctl>
		1330	and C<fcntl> as well (missing ones are, as usual C<0>):
		1331
		1332	C<F_DUPFD_CLOEXEC>,
		1333
		1334	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1335
		1336	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1337
		1338	C<F_ADD_SEALS>, C<F_GET_SEALS>, C<F_SEAL_SEAL>, C<F_SEAL_SHRINK>, C<F_SEAL_GROW> and
		1339	C<F_SEAL_WRITE>.
		1340
		1341	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1342	C<FS_IOC_FIEMAP>.
		1343
		1344	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1345	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1346
		1347	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1348	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1349	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1350	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1351	C<FS_FL_USER_MODIFIABLE>.
		1352
		1353	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1354	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1355	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1356	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1357
		1358	C<BLKROSET>, C<BLKROGET>, C<BLKRRPART>, C<BLKGETSIZE>, C<BLKFLSBUF>, C<BLKRASET>,
		1359	C<BLKRAGET>, C<BLKFRASET>, C<BLKFRAGET>, C<BLKSECTSET>, C<BLKSECTGET>, C<BLKSSZGET>,
		1360	C<BLKBSZGET>, C<BLKBSZSET>, C<BLKGETSIZE64>,
		1361
		1362
1016	=item aio_sync $callback->($status)	1363	=item aio_sync $callback->($status)
1017		1364
1018	Asynchronously call sync and call the callback when finished.	1365	Asynchronously call sync and call the callback when finished.
1019		1366
1020	=item aio_fsync $fh, $callback->($status)	1367	=item aio_fsync $fh, $callback->($status)
…		…
1027	Asynchronously call fdatasync on the given filehandle and call the	1374	Asynchronously call fdatasync on the given filehandle and call the
1028	callback with the fdatasync result code.	1375	callback with the fdatasync result code.
1029		1376
1030	If this call isn't available because your OS lacks it or it couldn't be	1377	If this call isn't available because your OS lacks it or it couldn't be
1031	detected, it will be emulated by calling C<fsync> instead.	1378	detected, it will be emulated by calling C<fsync> instead.
		1379
		1380	=item aio_syncfs $fh, $callback->($status)
		1381
		1382	Asynchronously call the syncfs syscall to sync the filesystem associated
		1383	to the given filehandle and call the callback with the syncfs result
		1384	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1385	errno to C<ENOSYS> nevertheless.
1032		1386
1033	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1387	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1034		1388
1035	Sync the data portion of the file specified by C<$offset> and C<$length>	1389	Sync the data portion of the file specified by C<$offset> and C<$length>
1036	to disk (but NOT the metadata), by calling the Linux-specific	1390	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1040	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1394	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1041	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1395	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1042	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1396	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1043	manpage for details.	1397	manpage for details.
1044		1398
1045	=item aio_pathsync $path, $callback->($status)	1399	=item aio_pathsync $pathname, $callback->($status)
1046		1400
1047	This request tries to open, fsync and close the given path. This is a	1401	This request tries to open, fsync and close the given path. This is a
1048	composite request intended to sync directories after directory operations	1402	composite request intended to sync directories after directory operations
1049	(E.g. rename). This might not work on all operating systems or have any	1403	(E.g. rename). This might not work on all operating systems or have any
1050	specific effect, but usually it makes sure that directory changes get	1404	specific effect, but usually it makes sure that directory changes get
…		…
1081	};	1435	};
1082		1436
1083	$grp	1437	$grp
1084	}	1438	}
1085		1439
1086	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1440	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1087		1441
1088	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1442	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1089	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1443	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1090	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1444	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1091	scalar must only be modified in-place while an aio operation is pending on	1445	scalar must only be modified in-place while an aio operation is pending on
…		…
1093		1447
1094	It calls the C<msync> function of your OS, if available, with the memory	1448	It calls the C<msync> function of your OS, if available, with the memory
1095	area starting at C<$offset> in the string and ending C<$length> bytes	1449	area starting at C<$offset> in the string and ending C<$length> bytes
1096	later. If C<$length> is negative, counts from the end, and if C<$length>	1450	later. If C<$length> is negative, counts from the end, and if C<$length>
1097	is C<undef>, then it goes till the end of the string. The flags can be	1451	is C<undef>, then it goes till the end of the string. The flags can be
1098	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1452	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1099	C<IO::AIO::MS_SYNC>.	1453	C<IO::AIO::MS_INVALIDATE>.
1100		1454
1101	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1455	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1102		1456
1103	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1457	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1104	scalars.	1458	scalars.
1105		1459
1106	It touches (reads or writes) all memory pages in the specified	1460	It touches (reads or writes) all memory pages in the specified
1107	range inside the scalar. All caveats and parameters are the same	1461	range inside the scalar. All caveats and parameters are the same
1108	as for C<aio_msync>, above, except for flags, which must be either	1462	as for C<aio_msync>, above, except for flags, which must be either
1109	C<0> (which reads all pages and ensures they are instantiated) or	1463	C<0> (which reads all pages and ensures they are instantiated) or
1110	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1464	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1111	writing an octet from it, which dirties the page).	1465	writing an octet from it, which dirties the page).
		1466
		1467	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1468
		1469	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1470	scalars.
		1471
		1472	It reads in all the pages of the underlying storage into memory (if any)
		1473	and locks them, so they are not getting swapped/paged out or removed.
		1474
		1475	If C<$length> is undefined, then the scalar will be locked till the end.
		1476
		1477	On systems that do not implement C<mlock>, this function returns C<-1>
		1478	and sets errno to C<ENOSYS>.
		1479
		1480	Note that the corresponding C<munlock> is synchronous and is
		1481	documented under L<MISCELLANEOUS FUNCTIONS>.
		1482
		1483	Example: open a file, mmap and mlock it - both will be undone when
		1484	C<$data> gets destroyed.
		1485
		1486	open my $fh, "<", $path or die "$path: $!";
		1487	my $data;
		1488	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1489	aio_mlock $data; # mlock in background
		1490
		1491	=item aio_mlockall $flags, $callback->($status)
		1492
		1493	Calls the C<mlockall> function with the given C<$flags> (a
		1494	combination of C<IO::AIO::MCL_CURRENT>, C<IO::AIO::MCL_FUTURE> and
		1495	C<IO::AIO::MCL_ONFAULT>).
		1496
		1497	On systems that do not implement C<mlockall>, this function returns C<-1>
		1498	and sets errno to C<ENOSYS>. Similarly, flag combinations not supported
		1499	by the system result in a return value of C<-1> with errno being set to
		1500	C<EINVAL>.
		1501
		1502	Note that the corresponding C<munlockall> is synchronous and is
		1503	documented under L<MISCELLANEOUS FUNCTIONS>.
		1504
		1505	Example: asynchronously lock all current and future pages into memory.
		1506
		1507	aio_mlockall IO::AIO::MCL_FUTURE;
		1508
		1509	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1510
		1511	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1512	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1513	the ioctl is not available on your OS, then this request will fail with
		1514	C<ENOSYS>.
		1515
		1516	C<$start> is the starting offset to query extents for, C<$length> is the
		1517	size of the range to query - if it is C<undef>, then the whole file will
		1518	be queried.
		1519
		1520	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1521	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1522	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1523	the data portion.
		1524
		1525	C<$count> is the maximum number of extent records to return. If it is
		1526	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1527	case, if it is C<0>, then the callback receives the number of extents
		1528	instead of the extents themselves (which is unreliable, see below).
		1529
		1530	If an error occurs, the callback receives no arguments. The special
		1531	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1532
		1533	Otherwise, the callback receives an array reference with extent
		1534	structures. Each extent structure is an array reference itself, with the
		1535	following members:
		1536
		1537	[$logical, $physical, $length, $flags]
		1538
		1539	Flags is any combination of the following flag values (typically either C<0>
		1540	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1541
		1542	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1543	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1544	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1545	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1546	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1547	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1548
		1549	At the time of this writing (Linux 3.2), this request is unreliable unless
		1550	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1551	it to return all extents of a range for files with a large number of
		1552	extents. The code (only) works around all these issues if C<$count> is
		1553	C<undef>.
1112		1554
1113	=item aio_group $callback->(...)	1555	=item aio_group $callback->(...)
1114		1556
1115	This is a very special aio request: Instead of doing something, it is a	1557	This is a very special aio request: Instead of doing something, it is a
1116	container for other aio requests, which is useful if you want to bundle	1558	container for other aio requests, which is useful if you want to bundle
…		…
1153	like sleep and file handle readable/writable, the overhead this creates is	1595	like sleep and file handle readable/writable, the overhead this creates is
1154	immense (it blocks a thread for a long time) so do not use this function	1596	immense (it blocks a thread for a long time) so do not use this function
1155	except to put your application under artificial I/O pressure.	1597	except to put your application under artificial I/O pressure.
1156		1598
1157	=back	1599	=back
		1600
		1601
		1602	=head2 IO::AIO::WD - multiple working directories
		1603
		1604	Your process only has one current working directory, which is used by all
		1605	threads. This makes it hard to use relative paths (some other component
		1606	could call C<chdir> at any time, and it is hard to control when the path
		1607	will be used by IO::AIO).
		1608
		1609	One solution for this is to always use absolute paths. This usually works,
		1610	but can be quite slow (the kernel has to walk the whole path on every
		1611	access), and can also be a hassle to implement.
		1612
		1613	Newer POSIX systems have a number of functions (openat, fdopendir,
		1614	futimensat and so on) that make it possible to specify working directories
		1615	per operation.
		1616
		1617	For portability, and because the clowns who "designed", or shall I write,
		1618	perpetrated this new interface were obviously half-drunk, this abstraction
		1619	cannot be perfect, though.
		1620
		1621	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1622	object. This object stores the canonicalised, absolute version of the
		1623	path, and on systems that allow it, also a directory file descriptor.
		1624
		1625	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1626	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1627	object and a pathname instead (or the IO::AIO::WD object alone, which
		1628	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1629	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1630	to that IO::AIO::WD object.
		1631
		1632	For example, to get a wd object for F</etc> and then stat F<passwd>
		1633	inside, you would write:
		1634
		1635	aio_wd "/etc", sub {
		1636	my $etcdir = shift;
		1637
		1638	# although $etcdir can be undef on error, there is generally no reason
		1639	# to check for errors here, as aio_stat will fail with ENOENT
		1640	# when $etcdir is undef.
		1641
		1642	aio_stat [$etcdir, "passwd"], sub {
		1643	# yay
		1644	};
		1645	};
		1646
		1647	The fact that C<aio_wd> is a request and not a normal function shows that
		1648	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1649	which is why it is done asynchronously.
		1650
		1651	To stat the directory obtained with C<aio_wd> above, one could write
		1652	either of the following three request calls:
		1653
		1654	aio_lstat "/etc" , sub { ... # pathname as normal string
		1655	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1656	aio_lstat $wd , sub { ... # shorthand for the previous
		1657
		1658	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1659	object and the pathname string, so you could write the following without
		1660	causing any issues due to C<$path> getting reused:
		1661
		1662	my $path = [$wd, undef];
		1663
		1664	for my $name (qw(abc def ghi)) {
		1665	$path->[1] = $name;
		1666	aio_stat $path, sub {
		1667	# ...
		1668	};
		1669	}
		1670
		1671	There are some caveats: when directories get renamed (or deleted), the
		1672	pathname string doesn't change, so will point to the new directory (or
		1673	nowhere at all), while the directory fd, if available on the system,
		1674	will still point to the original directory. Most functions accepting a
		1675	pathname will use the directory fd on newer systems, and the string on
		1676	older systems. Some functions (such as C<aio_realpath>) will always rely on
		1677	the string form of the pathname.
		1678
		1679	So this functionality is mainly useful to get some protection against
		1680	C<chdir>, to easily get an absolute path out of a relative path for future
		1681	reference, and to speed up doing many operations in the same directory
		1682	(e.g. when stat'ing all files in a directory).
		1683
		1684	The following functions implement this working directory abstraction:
		1685
		1686	=over 4
		1687
		1688	=item aio_wd $pathname, $callback->($wd)
		1689
		1690	Asynchonously canonicalise the given pathname and convert it to an
		1691	IO::AIO::WD object representing it. If possible and supported on the
		1692	system, also open a directory fd to speed up pathname resolution relative
		1693	to this working directory.
		1694
		1695	If something goes wrong, then C<undef> is passwd to the callback instead
		1696	of a working directory object and C<$!> is set appropriately. Since
		1697	passing C<undef> as working directory component of a pathname fails the
		1698	request with C<ENOENT>, there is often no need for error checking in the
		1699	C<aio_wd> callback, as future requests using the value will fail in the
		1700	expected way.
		1701
		1702	=item IO::AIO::CWD
		1703
		1704	This is a compile time constant (object) that represents the process
		1705	current working directory.
		1706
		1707	Specifying this object as working directory object for a pathname is as if
		1708	the pathname would be specified directly, without a directory object. For
		1709	example, these calls are functionally identical:
		1710
		1711	aio_stat "somefile", sub { ... };
		1712	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1713
		1714	=back
		1715
		1716	To recover the path associated with an IO::AIO::WD object, you can use
		1717	C<aio_realpath>:
		1718
		1719	aio_realpath $wd, sub {
		1720	warn "path is $_[0]\n";
		1721	};
		1722
		1723	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1724	sometimes, fall back to using an absolue path.
1158		1725
1159	=head2 IO::AIO::REQ CLASS	1726	=head2 IO::AIO::REQ CLASS
1160		1727
1161	All non-aggregate C<aio_*> functions return an object of this class when	1728	All non-aggregate C<aio_*> functions return an object of this class when
1162	called in non-void context.	1729	called in non-void context.
…		…
1280		1847
1281	Sets a feeder/generator on this group: every group can have an attached	1848	Sets a feeder/generator on this group: every group can have an attached
1282	generator that generates requests if idle. The idea behind this is that,	1849	generator that generates requests if idle. The idea behind this is that,
1283	although you could just queue as many requests as you want in a group,	1850	although you could just queue as many requests as you want in a group,
1284	this might starve other requests for a potentially long time. For example,	1851	this might starve other requests for a potentially long time. For example,
1285	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1852	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1286	delaying any later requests for a long time.	1853	requests, delaying any later requests for a long time.
1287		1854
1288	To avoid this, and allow incremental generation of requests, you can	1855	To avoid this, and allow incremental generation of requests, you can
1289	instead a group and set a feeder on it that generates those requests. The	1856	instead a group and set a feeder on it that generates those requests. The
1290	feed callback will be called whenever there are few enough (see C<limit>,	1857	feed callback will be called whenever there are few enough (see C<limit>,
1291	below) requests active in the group itself and is expected to queue more	1858	below) requests active in the group itself and is expected to queue more
…		…
1323	The default value for the limit is C<0>, but note that setting a feeder	1890	The default value for the limit is C<0>, but note that setting a feeder
1324	automatically bumps it up to C<2>.	1891	automatically bumps it up to C<2>.
1325		1892
1326	=back	1893	=back
1327		1894
		1895
1328	=head2 SUPPORT FUNCTIONS	1896	=head2 SUPPORT FUNCTIONS
1329		1897
1330	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1898	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1331		1899
1332	=over 4	1900	=over 4
…		…
1340		1908
1341	See C<poll_cb> for an example.	1909	See C<poll_cb> for an example.
1342		1910
1343	=item IO::AIO::poll_cb	1911	=item IO::AIO::poll_cb
1344		1912
1345	Process some outstanding events on the result pipe. You have to call this	1913	Process some requests that have reached the result phase (i.e. they have
1346	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1914	been executed but the results are not yet reported). You have to call
1347	returned earlier for whatever reason. Returns immediately when no events	1915	this "regularly" to finish outstanding requests.
1348	are outstanding. The amount of events processed depends on the settings of
1349	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1350		1916
		1917	Returns C<0> if all events could be processed (or there were no
		1918	events to process), or C<-1> if it returned earlier for whatever
		1919	reason. Returns immediately when no events are outstanding. The amount
		1920	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
		1921	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
		1922
1351	If not all requests were processed for whatever reason, the filehandle	1923	If not all requests were processed for whatever reason, the poll file
1352	will still be ready when C<poll_cb> returns, so normally you don't have to	1924	descriptor will still be ready when C<poll_cb> returns, so normally you
1353	do anything special to have it called later.	1925	don't have to do anything special to have it called later.
		1926
		1927	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1928	ready, it can be beneficial to call this function from loops which submit
		1929	a lot of requests, to make sure the results get processed when they become
		1930	available and not just when the loop is finished and the event loop takes
		1931	over again. This function returns very fast when there are no outstanding
		1932	requests.
1354		1933
1355	Example: Install an Event watcher that automatically calls	1934	Example: Install an Event watcher that automatically calls
1356	IO::AIO::poll_cb with high priority (more examples can be found in the	1935	IO::AIO::poll_cb with high priority (more examples can be found in the
1357	SYNOPSIS section, at the top of this document):	1936	SYNOPSIS section, at the top of this document):
1358		1937
…		…
1360	poll => 'r', async => 1,	1939	poll => 'r', async => 1,
1361	cb => \&IO::AIO::poll_cb);	1940	cb => \&IO::AIO::poll_cb);
1362		1941
1363	=item IO::AIO::poll_wait	1942	=item IO::AIO::poll_wait
1364		1943
1365	If there are any outstanding requests and none of them in the result	1944	Wait until either at least one request is in the result phase or no
1366	phase, wait till the result filehandle becomes ready for reading (simply	1945	requests are outstanding anymore.
1367	does a C<select> on the filehandle. This is useful if you want to	1946
1368	synchronously wait for some requests to finish).	1947	This is useful if you want to synchronously wait for some requests to
		1948	become ready, without actually handling them.
1369		1949
1370	See C<nreqs> for an example.	1950	See C<nreqs> for an example.
1371		1951
1372	=item IO::AIO::poll	1952	=item IO::AIO::poll
1373		1953
…		…
1384		1964
1385	Strictly equivalent to:	1965	Strictly equivalent to:
1386		1966
1387	IO::AIO::poll_wait, IO::AIO::poll_cb	1967	IO::AIO::poll_wait, IO::AIO::poll_cb
1388	while IO::AIO::nreqs;	1968	while IO::AIO::nreqs;
		1969
		1970	This function can be useful at program aborts, to make sure outstanding
		1971	I/O has been done (C<IO::AIO> uses an C<END> block which already calls
		1972	this function on normal exits), or when you are merely using C<IO::AIO>
		1973	for its more advanced functions, rather than for async I/O, e.g.:
		1974
		1975	my ($dirs, $nondirs);
		1976	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1977	IO::AIO::flush;
		1978	# $dirs, $nondirs are now set
1389		1979
1390	=item IO::AIO::max_poll_reqs $nreqs	1980	=item IO::AIO::max_poll_reqs $nreqs
1391		1981
1392	=item IO::AIO::max_poll_time $seconds	1982	=item IO::AIO::max_poll_time $seconds
1393		1983
…		…
1420	poll => 'r', nice => 1,	2010	poll => 'r', nice => 1,
1421	cb => &IO::AIO::poll_cb);	2011	cb => &IO::AIO::poll_cb);
1422		2012
1423	=back	2013	=back
1424		2014
		2015
1425	=head3 CONTROLLING THE NUMBER OF THREADS	2016	=head3 CONTROLLING THE NUMBER OF THREADS
1426		2017
1427	=over	2018	=over
1428		2019
1429	=item IO::AIO::min_parallel $nthreads	2020	=item IO::AIO::min_parallel $nthreads
…		…
1460		2051
1461	Under normal circumstances you don't need to call this function.	2052	Under normal circumstances you don't need to call this function.
1462		2053
1463	=item IO::AIO::max_idle $nthreads	2054	=item IO::AIO::max_idle $nthreads
1464		2055
1465	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	2056	Limit the number of threads (default: 4) that are allowed to idle
1466	threads that did not get a request to process within 10 seconds). That	2057	(i.e., threads that did not get a request to process within the idle
1467	means if a thread becomes idle while C<$nthreads> other threads are also	2058	timeout (default: 10 seconds). That means if a thread becomes idle while
1468	idle, it will free its resources and exit.	2059	C<$nthreads> other threads are also idle, it will free its resources and
		2060	exit.
1469		2061
1470	This is useful when you allow a large number of threads (e.g. 100 or 1000)	2062	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1471	to allow for extremely high load situations, but want to free resources	2063	to allow for extremely high load situations, but want to free resources
1472	under normal circumstances (1000 threads can easily consume 30MB of RAM).	2064	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1473		2065
1474	The default is probably ok in most situations, especially if thread	2066	The default is probably ok in most situations, especially if thread
1475	creation is fast. If thread creation is very slow on your system you might	2067	creation is fast. If thread creation is very slow on your system you might
1476	want to use larger values.	2068	want to use larger values.
1477		2069
		2070	=item IO::AIO::idle_timeout $seconds
		2071
		2072	Sets the minimum idle timeout (default 10) after which worker threads are
		2073	allowed to exit. SEe C<IO::AIO::max_idle>.
		2074
1478	=item IO::AIO::max_outstanding $maxreqs	2075	=item IO::AIO::max_outstanding $maxreqs
1479		2076
1480	This is a very bad function to use in interactive programs because it
1481	blocks, and a bad way to reduce concurrency because it is inexact: Better
1482	use an C<aio_group> together with a feed callback.
1483
1484	Sets the maximum number of outstanding requests to C<$nreqs>. If you	2077	Sets the maximum number of outstanding requests to C<$nreqs>. If
1485	do queue up more than this number of requests, the next call to the	2078	you do queue up more than this number of requests, the next call to
1486	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)	2079	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
1487	function will block until the limit is no longer exceeded.	2080	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		2081	longer exceeded.
1488		2082
1489	The default value is very large, so there is no practical limit on the	2083	In other words, this setting does not enforce a queue limit, but can be
1490	number of outstanding requests.	2084	used to make poll functions block if the limit is exceeded.
1491		2085
1492	You can still queue as many requests as you want. Therefore,	2086	This is a bad function to use in interactive programs because it blocks,
1493	C<max_outstanding> is mainly useful in simple scripts (with low values) or	2087	and a bad way to reduce concurrency because it is inexact. If you need to
1494	as a stop gap to shield against fatal memory overflow (with large values).	2088	issue many requests without being able to call a poll function on demand,
		2089	it is better to use an C<aio_group> together with a feed callback.
		2090
		2091	Its main use is in scripts without an event loop - when you want to stat a
		2092	lot of files, you can write something like this:
		2093
		2094	IO::AIO::max_outstanding 32;
		2095
		2096	for my $path (...) {
		2097	aio_stat $path , ...;
		2098	IO::AIO::poll_cb;
		2099	}
		2100
		2101	IO::AIO::flush;
		2102
		2103	The call to C<poll_cb> inside the loop will normally return instantly,
		2104	allowing the loop to progress, but as soon as more than C<32> requests
		2105	are in-flight, it will block until some requests have been handled. This
		2106	keeps the loop from pushing a large number of C<aio_stat> requests onto
		2107	the queue (which, with many paths to stat, can use up a lot of memory).
		2108
		2109	The default value for C<max_outstanding> is very large, so there is no
		2110	practical limit on the number of outstanding requests.
1495		2111
1496	=back	2112	=back
		2113
1497		2114
1498	=head3 STATISTICAL INFORMATION	2115	=head3 STATISTICAL INFORMATION
1499		2116
1500	=over	2117	=over
1501		2118
…		…
1519	Returns the number of requests currently in the pending state (executed,	2136	Returns the number of requests currently in the pending state (executed,
1520	but not yet processed by poll_cb).	2137	but not yet processed by poll_cb).
1521		2138
1522	=back	2139	=back
1523		2140
		2141
		2142	=head3 SUBSECOND STAT TIME ACCESS
		2143
		2144	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2145	generally find access/modification and change times with subsecond time
		2146	accuracy of the system supports it, but perl's built-in functions only
		2147	return the integer part.
		2148
		2149	The following functions return the timestamps of the most recent
		2150	stat with subsecond precision on most systems and work both after
		2151	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2152	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2153	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2154
		2155	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2156	full resolution without rounding and work with standard perl C<stat>,
		2157	alleviating the need to call the special C<Time::HiRes> functions, which
		2158	do not act like their perl counterparts.
		2159
		2160	On operating systems or file systems where subsecond time resolution is
		2161	not supported or could not be detected, a fractional part of C<0> is
		2162	returned, so it is always safe to call these functions.
		2163
		2164	=over 4
		2165
		2166	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		2167
		2168	Return the access, modication, change or birth time, respectively,
		2169	including fractional part. Due to the limited precision of floating point,
		2170	the accuracy on most platforms is only a bit better than milliseconds
		2171	for times around now - see the I<nsec> function family, below, for full
		2172	accuracy.
		2173
		2174	File birth time is only available when the OS and perl support it (on
		2175	FreeBSD and NetBSD at the time of this writing, although support is
		2176	adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
		2177	it). On systems where it isn't available, C<0> is currently returned, but
		2178	this might change to C<undef> in a future version.
		2179
		2180	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		2181
		2182	Returns access, modification, change and birth time all in one go, and
		2183	maybe more times in the future version.
		2184
		2185	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		2186
		2187	Return the fractional access, modifcation, change or birth time, in nanoseconds,
		2188	as an integer in the range C<0> to C<999999999>.
		2189
		2190	Note that no accessors are provided for access, modification and
		2191	change times - you need to get those from C<stat _> if required (C<int
		2192	IO::AIO::st_atime> and so on will I<not> generally give you the correct
		2193	value).
		2194
		2195	=item $seconds = IO::AIO::st_btimesec
		2196
		2197	The (integral) seconds part of the file birth time, if available.
		2198
		2199	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		2200
		2201	Like the functions above, but returns all four times in one go (and maybe
		2202	more in future versions).
		2203
		2204	=item $counter = IO::AIO::st_gen
		2205
		2206	Returns the generation counter (in practice this is just a random number)
		2207	of the file. This is only available on platforms which have this member in
		2208	their C<struct stat> (most BSDs at the time of this writing) and generally
		2209	only to the root usert. If unsupported, C<0> is returned, but this might
		2210	change to C<undef> in a future version.
		2211
		2212	=back
		2213
		2214	Example: print the high resolution modification time of F</etc>, using
		2215	C<stat>, and C<IO::AIO::aio_stat>.
		2216
		2217	if (stat "/etc") {
		2218	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2219	}
		2220
		2221	IO::AIO::aio_stat "/etc", sub {
		2222	$_[0]
		2223	and return;
		2224
		2225	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2226	};
		2227
		2228	IO::AIO::flush;
		2229
		2230	Output of the awbove on my system, showing reduced and full accuracy:
		2231
		2232	stat(/etc) mtime: 1534043702.020808
		2233	aio_stat(/etc) mtime: 1534043702.020807792
		2234
		2235
1524	=head3 MISCELLANEOUS FUNCTIONS	2236	=head3 MISCELLANEOUS FUNCTIONS
1525		2237
1526	IO::AIO implements some functions that might be useful, but are not	2238	IO::AIO implements some functions that are useful when you want to use
1527	asynchronous.	2239	some "Advanced I/O" function not available to in Perl, without going the
		2240	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2241	counterpart.
1528		2242
1529	=over 4	2243	=over 4
		2244
		2245	=item $retval = IO::AIO::fexecve $fh, $argv, $envp
		2246
		2247	A more-or-less direct equivalent to the POSIX C<fexecve> functions, which
		2248	allows you to specify the program to be executed via a file descriptor (or
		2249	handle). Returns C<-1> and sets errno to C<ENOSYS> if not available.
		2250
		2251	=item $retval = IO::AIO::mount $special, $path, $fstype, $flags = 0, $data = undef
		2252
		2253	Calls the GNU/Linux mount syscall with the given arguments. All except
		2254	C<$flags> are strings, and if C<$data> is C<undef>, a C<NULL> will be
		2255	passed.
		2256
		2257	The following values for C<$flags> are available:
		2258
		2259	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>,
		2260	C<IO::AIO::MS_REMOUNT>, C<IO::AIO::MS_MANDLOCK>, C<IO::AIO::MS_DIRSYNC>, C<IO::AIO::MS_NOATIME>,
		2261	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>,
		2262	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>,
		2263	C<IO::AIO::MS_RELATIME>, C<IO::AIO::MS_KERNMOUNT>, C<IO::AIO::MS_I_VERSION>, C<IO::AIO::MS_STRICTATIME>,
		2264	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
		2265	C<IO::AIO::MS_MGC_MSK>.
		2266
		2267	=item $retval = IO::AIO::umount $path, $flags = 0
		2268
		2269	Invokes the GNU/Linux C<umount> or C<umount2> syscalls. Always calls
		2270	C<umount> if C<$flags> is C<0>, otherwqise always tries to call
		2271	C<umount2>.
		2272
		2273	The following C<$flags> are available:
		2274
		2275	C<IO::AIO::MNT_FORCE>, C<IO::AIO::MNT_DETACH>, C<IO::AIO::MNT_EXPIRE> and C<IO::AIO::UMOUNT_NOFOLLOW>.
		2276
		2277	=item $numfd = IO::AIO::get_fdlimit
		2278
		2279	Tries to find the current file descriptor limit and returns it, or
		2280	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2281	the highest valid file descriptor number.
		2282
		2283	=item IO::AIO::min_fdlimit [$numfd]
		2284
		2285	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2286	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2287	is missing, it will try to set a very high limit, although this is not
		2288	recommended when you know the actual minimum that you require.
		2289
		2290	If the limit cannot be raised enough, the function makes a best-effort
		2291	attempt to increase the limit as much as possible, using various
		2292	tricks, while still failing. You can query the resulting limit using
		2293	C<IO::AIO::get_fdlimit>.
		2294
		2295	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2296	true.
1530		2297
1531	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2298	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1532		2299
1533	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2300	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1534	but is blocking (this makes most sense if you know the input data is	2301	but is blocking (this makes most sense if you know the input data is
…		…
1537		2304
1538	Returns the number of bytes copied, or C<-1> on error.	2305	Returns the number of bytes copied, or C<-1> on error.
1539		2306
1540	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2307	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1541		2308
1542	Simply calls the C<posix_fadvise> function (see it's	2309	Simply calls the C<posix_fadvise> function (see its
1543	manpage for details). The following advice constants are	2310	manpage for details). The following advice constants are
1544	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2311	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1545	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2312	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1546	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2313	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1547		2314
1548	On systems that do not implement C<posix_fadvise>, this function returns	2315	On systems that do not implement C<posix_fadvise>, this function returns
1549	ENOSYS, otherwise the return value of C<posix_fadvise>.	2316	ENOSYS, otherwise the return value of C<posix_fadvise>.
1550		2317
		2318	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		2319
		2320	Simply calls the C<posix_madvise> function (see its
		2321	manpage for details). The following advice constants are
		2322	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		2323	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2324	C<IO::AIO::MADV_DONTNEED>.
		2325
		2326	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2327	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2328	will be reduced to fit into the C<$scalar>.
		2329
		2330	On systems that do not implement C<posix_madvise>, this function returns
		2331	ENOSYS, otherwise the return value of C<posix_madvise>.
		2332
		2333	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		2334
		2335	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		2336	$scalar (see its manpage for details). The following protect
		2337	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		2338	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2339
		2340	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2341	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2342	will be reduced to fit into the C<$scalar>.
		2343
		2344	On systems that do not implement C<mprotect>, this function returns
		2345	ENOSYS, otherwise the return value of C<mprotect>.
		2346
1551	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2347	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1552		2348
1553	Memory-maps a file (or anonymous memory range) and attaches it to the	2349	Memory-maps a file (or anonymous memory range) and attaches it to the
1554	given C<$scalar>, which will act like a string scalar.	2350	given C<$scalar>, which will act like a string scalar. Returns true on
		2351	success, and false otherwise.
1555		2352
		2353	The scalar must exist, but its contents do not matter - this means you
		2354	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2355	the scalar first.
		2356
1556	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2357	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1557	change the string length, and most read-only operations such as copying it	2358	which don't change the string length, and most read-only operations such
1558	or searching it with regexes and so on.	2359	as copying it or searching it with regexes and so on.
1559		2360
1560	Anything else is unsafe and will, at best, result in memory leaks.	2361	Anything else is unsafe and will, at best, result in memory leaks.
1561		2362
1562	The memory map associated with the C<$scalar> is automatically removed	2363	The memory map associated with the C<$scalar> is automatically removed
1563	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2364	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1564	C<IO::AIO::munmap> functions are called.	2365	or C<IO::AIO::munmap> functions are called on it.
1565		2366
1566	This calls the C<mmap>(2) function internally. See your system's manual	2367	This calls the C<mmap>(2) function internally. See your system's manual
1567	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2368	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1568		2369
1569	The C<$length> must be larger than zero and smaller than the actual	2370	The C<$length> must be larger than zero and smaller than the actual
1570	filesize.	2371	filesize.
1571		2372
1572	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2373	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1573	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2374	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1574		2375
1575	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2376	C<$flags> can be a combination of
1576	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2377	C<IO::AIO::MAP_SHARED> or
1577	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2378	C<IO::AIO::MAP_PRIVATE>,
		2379	or a number of system-specific flags (when not available, the are C<0>):
1578	(which is set to C<MAP_ANON> if your system only provides this	2380	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1579	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2381	C<IO::AIO::MAP_LOCKED>,
1580	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2382	C<IO::AIO::MAP_NORESERVE>,
		2383	C<IO::AIO::MAP_POPULATE>,
1581	C<IO::AIO::MAP_NONBLOCK>	2384	C<IO::AIO::MAP_NONBLOCK>,
		2385	C<IO::AIO::MAP_FIXED>,
		2386	C<IO::AIO::MAP_GROWSDOWN>,
		2387	C<IO::AIO::MAP_32BIT>,
		2388	C<IO::AIO::MAP_HUGETLB>,
		2389	C<IO::AIO::MAP_STACK>,
		2390	C<IO::AIO::MAP_FIXED_NOREPLACE>,
		2391	C<IO::AIO::MAP_SHARED_VALIDATE>,
		2392	C<IO::AIO::MAP_SYNC> or
		2393	C<IO::AIO::MAP_UNINITIALIZED>.
1582		2394
1583	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2395	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1584		2396
1585	C<$offset> is the offset from the start of the file - it generally must be	2397	C<$offset> is the offset from the start of the file - it generally must be
1586	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2398	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1600		2412
1601	=item IO::AIO::munmap $scalar	2413	=item IO::AIO::munmap $scalar
1602		2414
1603	Removes a previous mmap and undefines the C<$scalar>.	2415	Removes a previous mmap and undefines the C<$scalar>.
1604		2416
		2417	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2418
		2419	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2420	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2421	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2422
		2423	Returns true if successful, and false otherwise. If the underlying mmapped
		2424	region has changed address, then the true value has the numerical value
		2425	C<1>, otherwise it has the numerical value C<0>:
		2426
		2427	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2428	or die "mremap: $!";
		2429
		2430	if ($success*1) {
		2431	warn "scalar has chanegd address in memory\n";
		2432	}
		2433
		2434	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2435	implemented, but not supported and might go away in a future version.
		2436
		2437	On systems where this call is not supported or is not emulated, this call
		2438	returns falls and sets C<$!> to C<ENOSYS>.
		2439
1605	=item IO::AIO::mlockall $flags	2440	=item IO::AIO::mlockall $flags
1606		2441
1607	Calls the C<mlockall> function with the given C<$flags> (a combination of	2442	Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
1608	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL__FUTURE>).	2443	but is blocking.
1609		2444
1610	On systems that do not implement C<mlockall>, this function returns	2445	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1611	ENOSYS, otherwise the return value of C<mlockall>.	2446
		2447	Calls the C<munlock> function, undoing the effects of a previous
		2448	C<aio_mlock> call (see its description for details).
1612		2449
1613	=item IO::AIO::munlockall	2450	=item IO::AIO::munlockall
1614		2451
1615	Calls the C<munlockall> function.	2452	Calls the C<munlockall> function.
1616		2453
1617	On systems that do not implement C<munlockall>, this function returns	2454	On systems that do not implement C<munlockall>, this function returns
1618	ENOSYS, otherwise the return value of C<munlockall>.	2455	ENOSYS, otherwise the return value of C<munlockall>.
		2456
		2457	=item $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		2458
		2459	Uses the GNU/Linux C<accept4(2)> syscall, if available, to accept a socket
		2460	and return the new file handle on success, or sets C<$!> and returns
		2461	C<undef> on error.
		2462
		2463	The remote name of the new socket will be stored in C<$sockaddr>, which
		2464	will be extended to allow for at least C<$sockaddr_maxlen> octets. If the
		2465	socket name does not fit into C<$sockaddr_maxlen> octets, this is signaled
		2466	by returning a longer string in C<$sockaddr>, which might or might not be
		2467	truncated.
		2468
		2469	To accept name-less sockets, use C<undef> for C<$sockaddr> and C<0> for
		2470	C<$sockaddr_maxlen>.
		2471
		2472	The main reasons to use this syscall rather than portable C<accept(2)>
		2473	are that you can specify C<SOCK_NONBLOCK> and/or C<SOCK_CLOEXEC>
		2474	flags and you can accept name-less sockets by specifying C<0> for
		2475	C<$sockaddr_maxlen>, which is sadly not possible with perl's interface to
		2476	C<accept>.
		2477
		2478	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2479
		2480	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2481	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2482	should be the file offset.
		2483
		2484	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2485	silently corrupt the data in this case.
		2486
		2487	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2488	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2489	C<IO::AIO::SPLICE_F_GIFT>.
		2490
		2491	See the C<splice(2)> manpage for details.
		2492
		2493	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2494
		2495	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2496	description for C<IO::AIO::splice> above for details.
		2497
		2498	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2499
		2500	Attempts to query or change the pipe buffer size. Obviously works only
		2501	on pipes, and currently works only on GNU/Linux systems, and fails with
		2502	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2503	size on other systems, drop me a note.
		2504
		2505	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2506
		2507	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2508	C<$flags> is missing or C<0>, then this should be the same as a call to
		2509	perl's built-in C<pipe> function and create a new pipe, and works on
		2510	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2511	(..., 4096, O_BINARY)>.
		2512
		2513	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2514	the given flags (Linux 2.6.27, glibc 2.9).
		2515
		2516	On success, the read and write file handles are returned.
		2517
		2518	On error, nothing will be returned. If the pipe2 syscall is missing and
		2519	C<$flags> is non-zero, fails with C<ENOSYS>.
		2520
		2521	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2522	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2523	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2524
		2525	Example: create a pipe race-free w.r.t. threads and fork:
		2526
		2527	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2528	or die "pipe2: $!\n";
		2529
		2530	=item $fh = IO::AIO::memfd_create $pathname[, $flags]
		2531
		2532	This is a direct interface to the Linux L<memfd_create(2)> system
		2533	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2534	should be C<IO::AIO::MFD_CLOEXEC>.
		2535
		2536	On success, the new memfd filehandle is returned, otherwise returns
		2537	C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
		2538
		2539	Please refer to L<memfd_create(2)> for more info on this call.
		2540
		2541	The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
		2542	C<IO::AIO::MFD_ALLOW_SEALING>, C<IO::AIO::MFD_HUGETLB>,
		2543	C<IO::AIO::MFD_HUGETLB_2MB> and C<IO::AIO::MFD_HUGETLB_1GB>.
		2544
		2545	Example: create a new memfd.
		2546
		2547	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2548	or die "memfd_create: $!\n";
		2549
		2550	=item $fh = IO::AIO::pidfd_open $pid[, $flags]
		2551
		2552	This is an interface to the Linux L<pidfd_open(2)> system call. The
		2553	default for C<$flags> is C<0>.
		2554
		2555	On success, a new pidfd filehandle is returned (that is already set to
		2556	close-on-exec), otherwise returns C<undef>. If the syscall is missing,
		2557	fails with C<ENOSYS>.
		2558
		2559	Example: open pid 6341 as pidfd.
		2560
		2561	my $fh = IO::AIO::pidfd_open 6341
		2562	or die "pidfd_open: $!\n";
		2563
		2564	=item $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		2565
		2566	This is an interface to the Linux L<pidfd_send_signal> system call. The
		2567	default for C<$siginfo> is C<undef> and the default for C<$flags> is C<0>.
		2568
		2569	Returns the system call status. If the syscall is missing, fails with
		2570	C<ENOSYS>.
		2571
		2572	When specified, C<$siginfo> must be a reference to a hash with one or more
		2573	of the following members:
		2574
		2575	=over
		2576
		2577	=item code - the C<si_code> member
		2578
		2579	=item pid - the C<si_pid> member
		2580
		2581	=item uid - the C<si_uid> member
		2582
		2583	=item value_int - the C<si_value.sival_int> member
		2584
		2585	=item value_ptr - the C<si_value.sival_ptr> member, specified as an integer
		2586
		2587	=back
		2588
		2589	Example: send a SIGKILL to the specified process.
		2590
		2591	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
		2592	and die "pidfd_send_signal: $!\n";
		2593
		2594	Example: send a SIGKILL to the specified process with extra data.
		2595
		2596	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
		2597	and die "pidfd_send_signal: $!\n";
		2598
		2599	=item $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		2600
		2601	This is an interface to the Linux L<pidfd_getfd> system call. The default
		2602	for C<$flags> is C<0>.
		2603
		2604	On success, returns a dup'ed copy of the target file descriptor (specified
		2605	as an integer) returned (that is already set to close-on-exec), otherwise
		2606	returns C<undef>. If the syscall is missing, fails with C<ENOSYS>.
		2607
		2608	Example: get a copy of standard error of another process and print soemthing to it.
		2609
		2610	my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
		2611	or die "pidfd_getfd: $!\n";
		2612	print $errfh "stderr\n";
		2613
		2614	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2615
		2616	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2617	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2618
		2619	On success, the new eventfd filehandle is returned, otherwise returns
		2620	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2621
		2622	Please refer to L<eventfd(2)> for more info on this call.
		2623
		2624	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2625	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2626
		2627	Example: create a new eventfd filehandle:
		2628
		2629	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2630	or die "eventfd: $!\n";
		2631
		2632	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2633
		2634	This is a direct interface to the Linux L<timerfd_create(2)> system
		2635	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2636	should be C<IO::AIO::TFD_CLOEXEC>.
		2637
		2638	On success, the new timerfd filehandle is returned, otherwise returns
		2639	C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
		2640
		2641	Please refer to L<timerfd_create(2)> for more info on this call.
		2642
		2643	The following C<$clockid> values are
		2644	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2645	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2646	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2647	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2648
		2649	The following C<$flags> values are available (Linux
		2650	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2651
		2652	Example: create a new timerfd and set it to one-second repeated alarms,
		2653	then wait for two alarms:
		2654
		2655	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2656	or die "timerfd_create: $!\n";
		2657
		2658	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2659	or die "timerfd_settime: $!\n";
		2660
		2661	for (1..2) {
		2662	8 == sysread $fh, my $buf, 8
		2663	or die "timerfd read failure\n";
		2664
		2665	printf "number of expirations (likely 1): %d\n",
		2666	unpack "Q", $buf;
		2667	}
		2668
		2669	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2670
		2671	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2672	call. Please refer to its manpage for more info on this call.
		2673
		2674	The new itimerspec is specified using two (possibly fractional) second
		2675	values, C<$new_interval> and C<$new_value>).
		2676
		2677	On success, the current interval and value are returned (as per
		2678	C<timerfd_gettime>). On failure, the empty list is returned.
		2679
		2680	The following C<$flags> values are
		2681	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2682	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2683
		2684	See C<IO::AIO::timerfd_create> for a full example.
		2685
		2686	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2687
		2688	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2689	call. Please refer to its manpage for more info on this call.
		2690
		2691	On success, returns the current values of interval and value for the given
		2692	timerfd (as potentially fractional second values). On failure, the empty
		2693	list is returned.
1619		2694
1620	=back	2695	=back
1621		2696
1622	=cut	2697	=cut
1623		2698
…		…
1658	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	2733	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1659	\&IO::AIO::poll_cb);	2734	\&IO::AIO::poll_cb);
1660		2735
1661	=head2 FORK BEHAVIOUR	2736	=head2 FORK BEHAVIOUR
1662		2737
1663	This module should do "the right thing" when the process using it forks:	2738	Usage of pthreads in a program changes the semantics of fork
		2739	considerably. Specifically, only async-safe functions can be called after
		2740	fork. Perl doesn't know about this, so in general, you cannot call fork
		2741	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2742	pthreads, so this applies, but many other extensions and (for inexplicable
		2743	reasons) perl itself often is linked against pthreads, so this limitation
		2744	applies to quite a lot of perls.
1664		2745
1665	Before the fork, IO::AIO enters a quiescent state where no requests	2746	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1666	can be added in other threads and no results will be processed. After	2747	only works in the process that loaded it. Forking is fully supported, but
1667	the fork the parent simply leaves the quiescent state and continues	2748	using IO::AIO in the child is not.
1668	request/result processing, while the child frees the request/result queue
1669	(so that the requests started before the fork will only be handled in the
1670	parent). Threads will be started on demand until the limit set in the
1671	parent process has been reached again.
1672		2749
1673	In short: the parent will, after a short pause, continue as if fork had	2750	You might get around by not I<using> IO::AIO before (or after)
1674	not been called, while the child will act as if IO::AIO has not been used	2751	forking. You could also try to call the L<IO::AIO::reinit> function in the
1675	yet.	2752	child:
		2753
		2754	=over 4
		2755
		2756	=item IO::AIO::reinit
		2757
		2758	Abandons all current requests and I/O threads and simply reinitialises all
		2759	data structures. This is not an operation supported by any standards, but
		2760	happens to work on GNU/Linux and some newer BSD systems.
		2761
		2762	The only reasonable use for this function is to call it after forking, if
		2763	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2764	the process will result in undefined behaviour. Calling it at any time
		2765	will also result in any undefined (by POSIX) behaviour.
		2766
		2767	=back
		2768
		2769	=head2 LINUX-SPECIFIC CALLS
		2770
		2771	When a call is documented as "linux-specific" then this means it
		2772	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2773	availability and compatibility of such calls regardless of the platform
		2774	it is compiled on, so platforms such as FreeBSD which often implement
		2775	these calls will work. When in doubt, call them and see if they fail wth
		2776	C<ENOSYS>.
1676		2777
1677	=head2 MEMORY USAGE	2778	=head2 MEMORY USAGE
1678		2779
1679	Per-request usage:	2780	Per-request usage:
1680		2781
…		…
1693	temporary buffers, and each thread requires a stack and other data	2794	temporary buffers, and each thread requires a stack and other data
1694	structures (usually around 16k-128k, depending on the OS).	2795	structures (usually around 16k-128k, depending on the OS).
1695		2796
1696	=head1 KNOWN BUGS	2797	=head1 KNOWN BUGS
1697		2798
1698	Known bugs will be fixed in the next release.	2799	Known bugs will be fixed in the next release :)
		2800
		2801	=head1 KNOWN ISSUES
		2802
		2803	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2804	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2805	non-created hash slots or other scalars I didn't think of. It's best to
		2806	avoid such and either use scalar variables or making sure that the scalar
		2807	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2808
		2809	I am not sure anything can be done about this, so this is considered a
		2810	known issue, rather than a bug.
1699		2811
1700	=head1 SEE ALSO	2812	=head1 SEE ALSO
1701		2813
1702	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2814	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1703	more natural syntax.	2815	more natural syntax and L<IO::FDPass> for file descriptor passing.
1704		2816
1705	=head1 AUTHOR	2817	=head1 AUTHOR
1706		2818
1707	Marc Lehmann <schmorp@schmorp.de>	2819	Marc Lehmann <schmorp@schmorp.de>
1708	http://home.schmorp.de/	2820	http://home.schmorp.de/

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