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Revision 1.209 by root, Tue Sep 27 00:41:51 2011 UTC vs.
Revision 1.304 by root, Wed Apr 3 03:11:45 2019 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	IO::AIO - Asynchronous Input/Output	3	IO::AIO - Asynchronous/Advanced Input/Output
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
…		…
58	not well-supported or restricted (GNU/Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
59	files currently, for example), and they would only support aio_read and	59	files currently, for example), and they would only support aio_read and
60	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
61	using threads anyway.	61	using threads anyway.
62		62
		63	In addition to asynchronous I/O, this module also exports some rather
		64	arcane interfaces, such as C<madvise> or linux's C<splice> system call,
		65	which is why the C<A> in C<AIO> can also mean I<advanced>.
		66
63	Although the module will work in the presence of other (Perl-) threads,	67	Although the module will work in the presence of other (Perl-) threads,
64	it is currently not reentrant in any way, so use appropriate locking	68	it is currently not reentrant in any way, so use appropriate locking
65	yourself, always call C<poll_cb> from within the same thread, or never	69	yourself, always call C<poll_cb> from within the same thread, or never
66	call C<poll_cb> (or other C<aio_> functions) recursively.	70	call C<poll_cb> (or other C<aio_> functions) recursively.
67		71
68	=head2 EXAMPLE	72	=head2 EXAMPLE
69		73
70	This is a simple example that uses the EV module and loads	74	This is a simple example that uses the EV module and loads
71	F</etc/passwd> asynchronously:	75	F</etc/passwd> asynchronously:
72		76
73	use Fcntl;
74	use EV;	77	use EV;
75	use IO::AIO;	78	use IO::AIO;
76		79
77	# register the IO::AIO callback with EV	80	# register the IO::AIO callback with EV
78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	81	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
…		…
95		98
96	# file contents now in $contents	99	# file contents now in $contents
97	print $contents;	100	print $contents;
98		101
99	# exit event loop and program	102	# exit event loop and program
100	EV::unloop;	103	EV::break;
101	};	104	};
102	};	105	};
103		106
104	# possibly queue up other requests, or open GUI windows,	107	# possibly queue up other requests, or open GUI windows,
105	# check for sockets etc. etc.	108	# check for sockets etc. etc.
106		109
107	# process events as long as there are some:	110	# process events as long as there are some:
108	EV::loop;	111	EV::run;
109		112
110	=head1 REQUEST ANATOMY AND LIFETIME	113	=head1 REQUEST ANATOMY AND LIFETIME
111		114
112	Every C<aio_*> function creates a request. which is a C data structure not	115	Every C<aio_*> function creates a request. which is a C data structure not
113	directly visible to Perl.	116	directly visible to Perl.
…		…
168	use common::sense;	171	use common::sense;
169		172
170	use base 'Exporter';	173	use base 'Exporter';
171		174
172	BEGIN {	175	BEGIN {
173	our $VERSION = '4.0';	176	our $VERSION = 4.72;
174		177
175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	178	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx	179	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate	181	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
179	aio_pathsync aio_readahead	182	aio_pathsync aio_readahead aio_fiemap aio_allocate
180	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
181	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	184	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
182	aio_chmod aio_utime aio_truncate	185	aio_chmod aio_utime aio_truncate
183	aio_msync aio_mtouch aio_mlock aio_mlockall	186	aio_msync aio_mtouch aio_mlock aio_mlockall
184	aio_statvfs	187	aio_statvfs
		188	aio_slurp
185	aio_wd);	189	aio_wd);
186		190
187	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	191	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
188	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	192	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
189	min_parallel max_parallel max_idle idle_timeout	193	min_parallel max_parallel max_idle idle_timeout
190	nreqs nready npending nthreads	194	nreqs nready npending nthreads
191	max_poll_time max_poll_reqs	195	max_poll_time max_poll_reqs
192	sendfile fadvise madvise	196	sendfile fadvise madvise
193	mmap munmap munlock munlockall);	197	mmap munmap mremap munlock munlockall);
194		198
195	push @AIO_REQ, qw(aio_busy); # not exported	199	push @AIO_REQ, qw(aio_busy); # not exported
196		200
197	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	201	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
198		202
…		…
202		206
203	=head1 FUNCTIONS	207	=head1 FUNCTIONS
204		208
205	=head2 QUICK OVERVIEW	209	=head2 QUICK OVERVIEW
206		210
207	This section simply lists the prototypes of the most important functions	211	This section simply lists the prototypes most of the functions for
208	for quick reference. See the following sections for function-by-function	212	quick reference. See the following sections for function-by-function
209	documentation.	213	documentation.
210		214
211	aio_wd $pathname, $callback->($wd)	215	aio_wd $pathname, $callback->($wd)
212	aio_open $pathname, $flags, $mode, $callback->($fh)	216	aio_open $pathname, $flags, $mode, $callback->($fh)
213	aio_close $fh, $callback->($status)	217	aio_close $fh, $callback->($status)
		218	aio_seek $fh,$offset,$whence, $callback->($offs)
214	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	219	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
215	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	220	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
216	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	221	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
217	aio_readahead $fh,$offset,$length, $callback->($retval)	222	aio_readahead $fh,$offset,$length, $callback->($retval)
218	aio_stat $fh_or_path, $callback->($status)	223	aio_stat $fh_or_path, $callback->($status)
219	aio_lstat $fh, $callback->($status)	224	aio_lstat $fh, $callback->($status)
220	aio_statvfs $fh_or_path, $callback->($statvfs)	225	aio_statvfs $fh_or_path, $callback->($statvfs)
221	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	226	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
222	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	227	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		228	aio_chmod $fh_or_path, $mode, $callback->($status)
223	aio_truncate $fh_or_path, $offset, $callback->($status)	229	aio_truncate $fh_or_path, $offset, $callback->($status)
224	aio_chmod $fh_or_path, $mode, $callback->($status)	230	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		231	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
225	aio_unlink $pathname, $callback->($status)	232	aio_unlink $pathname, $callback->($status)
226	aio_mknod $pathname, $mode, $dev, $callback->($status)	233	aio_mknod $pathname, $mode, $dev, $callback->($status)
227	aio_link $srcpath, $dstpath, $callback->($status)	234	aio_link $srcpath, $dstpath, $callback->($status)
228	aio_symlink $srcpath, $dstpath, $callback->($status)	235	aio_symlink $srcpath, $dstpath, $callback->($status)
229	aio_readlink $pathname, $callback->($link)	236	aio_readlink $pathname, $callback->($link)
230	aio_realpath $pathname, $callback->($link)	237	aio_realpath $pathname, $callback->($path)
231	aio_rename $srcpath, $dstpath, $callback->($status)	238	aio_rename $srcpath, $dstpath, $callback->($status)
		239	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
232	aio_mkdir $pathname, $mode, $callback->($status)	240	aio_mkdir $pathname, $mode, $callback->($status)
233	aio_rmdir $pathname, $callback->($status)	241	aio_rmdir $pathname, $callback->($status)
234	aio_readdir $pathname, $callback->($entries)	242	aio_readdir $pathname, $callback->($entries)
235	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	243	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
236	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	244	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
237	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	245	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		246	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
238	aio_load $pathname, $data, $callback->($status)	247	aio_load $pathname, $data, $callback->($status)
239	aio_copy $srcpath, $dstpath, $callback->($status)	248	aio_copy $srcpath, $dstpath, $callback->($status)
240	aio_move $srcpath, $dstpath, $callback->($status)	249	aio_move $srcpath, $dstpath, $callback->($status)
241	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
242	aio_rmtree $pathname, $callback->($status)	250	aio_rmtree $pathname, $callback->($status)
		251	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		252	aio_ioctl $fh, $request, $buf, $callback->($status)
243	aio_sync $callback->($status)	253	aio_sync $callback->($status)
244	aio_syncfs $fh, $callback->($status)	254	aio_syncfs $fh, $callback->($status)
245	aio_fsync $fh, $callback->($status)	255	aio_fsync $fh, $callback->($status)
246	aio_fdatasync $fh, $callback->($status)	256	aio_fdatasync $fh, $callback->($status)
247	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	257	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
248	aio_pathsync $pathname, $callback->($status)	258	aio_pathsync $pathname, $callback->($status)
249	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	259	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
250	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	260	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
251	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	261	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
252	aio_mlockall $flags, $callback->($status)	262	aio_mlockall $flags, $callback->($status)
253	aio_group $callback->(...)	263	aio_group $callback->(...)
254	aio_nop $callback->()	264	aio_nop $callback->()
…		…
268	IO::AIO::idle_timeout $seconds	278	IO::AIO::idle_timeout $seconds
269	IO::AIO::max_outstanding $maxreqs	279	IO::AIO::max_outstanding $maxreqs
270	IO::AIO::nreqs	280	IO::AIO::nreqs
271	IO::AIO::nready	281	IO::AIO::nready
272	IO::AIO::npending	282	IO::AIO::npending
		283	IO::AIO::reinit
		284
		285	$nfd = IO::AIO::get_fdlimit [EXPERIMENTAL]
		286	IO::AIO::min_fdlimit $nfd [EXPERIMENTAL]
273		287
274	IO::AIO::sendfile $ofh, $ifh, $offset, $count	288	IO::AIO::sendfile $ofh, $ifh, $offset, $count
275	IO::AIO::fadvise $fh, $offset, $len, $advice	289	IO::AIO::fadvise $fh, $offset, $len, $advice
		290
		291	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		292	IO::AIO::munmap $scalar
		293	IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
276	IO::AIO::madvise $scalar, $offset, $length, $advice	294	IO::AIO::madvise $scalar, $offset, $length, $advice
277	IO::AIO::mprotect $scalar, $offset, $length, $protect	295	IO::AIO::mprotect $scalar, $offset, $length, $protect
278	IO::AIO::munlock $scalar, $offset = 0, $length = undef	296	IO::AIO::munlock $scalar, $offset = 0, $length = undef
279	IO::AIO::munlockall	297	IO::AIO::munlockall
280		298
281	=head2 AIO REQUEST FUNCTIONS	299	# stat extensions
		300	$counter = IO::AIO::st_gen
		301	$seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		302	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		303	$nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		304	$seconds = IO::AIO::st_btimesec
		305	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		306
		307	# very much unportable syscalls
		308	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		309	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		310	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		311	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		312	$fh = IO::AIO::memfd_create $pathname[, $flags]
		313	$fh = IO::AIO::eventfd [$initval, [$flags]]
		314	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		315	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		316	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		317
		318	=head2 API NOTES
282		319
283	All the C<aio_*> calls are more or less thin wrappers around the syscall	320	All the C<aio_*> calls are more or less thin wrappers around the syscall
284	with the same name (sans C<aio_>). The arguments are similar or identical,	321	with the same name (sans C<aio_>). The arguments are similar or identical,
285	and they all accept an additional (and optional) C<$callback> argument	322	and they all accept an additional (and optional) C<$callback> argument
286	which must be a code reference. This code reference will get called with	323	which must be a code reference. This code reference will be called after
287	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	324	the syscall has been executed in an asynchronous fashion. The results
288	perl, which usually delivers "false") as its sole argument after the given	325	of the request will be passed as arguments to the callback (and, if an
289	syscall has been executed asynchronously.	326	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		327	most syscalls return C<-1> on error, unlike perl, which usually delivers
		328	"false").
		329
		330	Some requests (such as C<aio_readdir>) pass the actual results and
		331	communicate failures by passing C<undef>.
290		332
291	All functions expecting a filehandle keep a copy of the filehandle	333	All functions expecting a filehandle keep a copy of the filehandle
292	internally until the request has finished.	334	internally until the request has finished.
293		335
294	All functions return request objects of type L<IO::AIO::REQ> that allow	336	All functions return request objects of type L<IO::AIO::REQ> that allow
295	further manipulation of those requests while they are in-flight.	337	further manipulation of those requests while they are in-flight.
296		338
297	The pathnames you pass to these routines I<should> be absolute. The	339	The pathnames you pass to these routines I<should> be absolute. The
298	reason for this is that at the time the request is being executed, the	340	reason for this is that at the time the request is being executed, the
299	current working directory could have changed. Alternatively, you can make	341	current working directory could have changed. Alternatively, you can
300	sure that you never change the current working directory anywhere in	342	make sure that you never change the current working directory anywhere
301	the program and then use relative paths. Lastly, you can take advantage	343	in the program and then use relative paths. You can also take advantage
302	of IO::AIOs working directory abstraction - see the description of the	344	of IO::AIOs working directory abstraction, that lets you specify paths
		345	relative to some previously-opened "working directory object" - see the
303	C<IO::AIO::WD> class later in this document.	346	description of the C<IO::AIO::WD> class later in this document.
304		347
305	To encode pathnames as octets, either make sure you either: a) always pass	348	To encode pathnames as octets, either make sure you either: a) always pass
306	in filenames you got from outside (command line, readdir etc.) without	349	in filenames you got from outside (command line, readdir etc.) without
307	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	350	tinkering, b) are in your native filesystem encoding, c) use the Encode
308	your pathnames to the locale (or other) encoding in effect in the user	351	module and encode your pathnames to the locale (or other) encoding in
309	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	352	effect in the user environment, d) use Glib::filename_from_unicode on
310	use something else to ensure your scalar has the correct contents.	353	unicode filenames or e) use something else to ensure your scalar has the
		354	correct contents.
311		355
312	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	356	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
313	handles correctly whether it is set or not.	357	handles correctly whether it is set or not.
		358
		359	=head2 AIO REQUEST FUNCTIONS
314		360
315	=over 4	361	=over 4
316		362
317	=item $prev_pri = aioreq_pri [$pri]	363	=item $prev_pri = aioreq_pri [$pri]
318		364
…		…
348		394
349		395
350	=item aio_open $pathname, $flags, $mode, $callback->($fh)	396	=item aio_open $pathname, $flags, $mode, $callback->($fh)
351		397
352	Asynchronously open or create a file and call the callback with a newly	398	Asynchronously open or create a file and call the callback with a newly
353	created filehandle for the file.	399	created filehandle for the file (or C<undef> in case of an error).
354		400
355	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	401	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
356	for an explanation.	402	for an explanation.
357		403
358	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	404	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
381	following POSIX and non-POSIX constants are available (missing ones on	427	following POSIX and non-POSIX constants are available (missing ones on
382	your system are, as usual, C<0>):	428	your system are, as usual, C<0>):
383		429
384	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,	430	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
385	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,	431	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
386	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.	432	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
387		433
388		434
389	=item aio_close $fh, $callback->($status)	435	=item aio_close $fh, $callback->($status)
390		436
391	Asynchronously close a file and call the callback with the result	437	Asynchronously close a file and call the callback with the result
…		…
401	Or in other words: the file descriptor will be closed, but it will not be	447	Or in other words: the file descriptor will be closed, but it will not be
402	free for reuse until the perl filehandle is closed.	448	free for reuse until the perl filehandle is closed.
403		449
404	=cut	450	=cut
405		451
		452	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		453
		454	Seeks the filehandle to the new C<$offset>, similarly to perl's
		455	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		456	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		457	C<IO::AIO::SEEK_END>).
		458
		459	The resulting absolute offset will be passed to the callback, or C<-1> in
		460	case of an error.
		461
		462	In theory, the C<$whence> constants could be different than the
		463	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		464	so don't panic.
		465
		466	As a GNU/Linux (and maybe Solaris) extension, also the constants
		467	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		468	could be found. No guarantees about suitability for use in C<aio_seek> or
		469	Perl's C<sysseek> can be made though, although I would naively assume they
		470	"just work".
		471
406	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	472	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
407		473
408	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	474	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
409		475
410	Reads or writes C<$length> bytes from or to the specified C<$fh> and	476	Reads or writes C<$length> bytes from or to the specified C<$fh> and
411	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	477	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
412	and calls the callback without the actual number of bytes read (or -1 on	478	calls the callback with the actual number of bytes transferred (or -1 on
413	error, just like the syscall).	479	error, just like the syscall).
414		480
415	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	481	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
416	offset plus the actual number of bytes read.	482	offset plus the actual number of bytes read.
417		483
…		…
475	As native sendfile syscalls (as practically any non-POSIX interface hacked	541	As native sendfile syscalls (as practically any non-POSIX interface hacked
476	together in a hurry to improve benchmark numbers) tend to be rather buggy	542	together in a hurry to improve benchmark numbers) tend to be rather buggy
477	on many systems, this implementation tries to work around some known bugs	543	on many systems, this implementation tries to work around some known bugs
478	in Linux and FreeBSD kernels (probably others, too), but that might fail,	544	in Linux and FreeBSD kernels (probably others, too), but that might fail,
479	so you really really should check the return value of C<aio_sendfile> -	545	so you really really should check the return value of C<aio_sendfile> -
480	fewre bytes than expected might have been transferred.	546	fewer bytes than expected might have been transferred.
481		547
482		548
483	=item aio_readahead $fh,$offset,$length, $callback->($retval)	549	=item aio_readahead $fh,$offset,$length, $callback->($retval)
484		550
485	C<aio_readahead> populates the page cache with data from a file so that	551	C<aio_readahead> populates the page cache with data from a file so that
…		…
489	whole pages, so that offset is effectively rounded down to a page boundary	555	whole pages, so that offset is effectively rounded down to a page boundary
490	and bytes are read up to the next page boundary greater than or equal to	556	and bytes are read up to the next page boundary greater than or equal to
491	(off-set+length). C<aio_readahead> does not read beyond the end of the	557	(off-set+length). C<aio_readahead> does not read beyond the end of the
492	file. The current file offset of the file is left unchanged.	558	file. The current file offset of the file is left unchanged.
493		559
494	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	560	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
495	emulated by simply reading the data, which would have a similar effect.	561	be emulated by simply reading the data, which would have a similar effect.
496		562
497		563
498	=item aio_stat $fh_or_path, $callback->($status)	564	=item aio_stat $fh_or_path, $callback->($status)
499		565
500	=item aio_lstat $fh, $callback->($status)	566	=item aio_lstat $fh, $callback->($status)
501		567
502	Works like perl's C<stat> or C<lstat> in void context. The callback will	568	Works almost exactly like perl's C<stat> or C<lstat> in void context. The
503	be called after the stat and the results will be available using C<stat _>	569	callback will be called after the stat and the results will be available
504	or C<-s _> etc...	570	using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
		571	and C<-T>).
505		572
506	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,	573	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
507	for an explanation.	574	for an explanation.
508		575
509	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	576	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
…		…
516	behaviour).	583	behaviour).
517		584
518	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,	585	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
519	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,	586	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
520	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.	587	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		588
		589	To access higher resolution stat timestamps, see L<SUBSECOND STAT TIME
		590	ACCESS>.
521		591
522	Example: Print the length of F</etc/passwd>:	592	Example: Print the length of F</etc/passwd>:
523		593
524	aio_stat "/etc/passwd", sub {	594	aio_stat "/etc/passwd", sub {
525	$_[0] and die "stat failed: $!";	595	$_[0] and die "stat failed: $!";
…		…
569	namemax => 255,	639	namemax => 255,
570	frsize => 1024,	640	frsize => 1024,
571	fsid => 1810	641	fsid => 1810
572	}	642	}
573		643
574
575	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	644	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
576		645
577	Works like perl's C<utime> function (including the special case of $atime	646	Works like perl's C<utime> function (including the special case of $atime
578	and $mtime being undef). Fractional times are supported if the underlying	647	and $mtime being undef). Fractional times are supported if the underlying
579	syscalls support them.	648	syscalls support them.
580		649
581	When called with a pathname, uses utimes(2) if available, otherwise	650	When called with a pathname, uses utimensat(2) or utimes(2) if available,
582	utime(2). If called on a file descriptor, uses futimes(2) if available,	651	otherwise utime(2). If called on a file descriptor, uses futimens(2)
583	otherwise returns ENOSYS, so this is not portable.	652	or futimes(2) if available, otherwise returns ENOSYS, so this is not
		653	portable.
584		654
585	Examples:	655	Examples:
586		656
587	# set atime and mtime to current time (basically touch(1)):	657	# set atime and mtime to current time (basically touch(1)):
588	aio_utime "path", undef, undef;	658	aio_utime "path", undef, undef;
…		…
606	=item aio_truncate $fh_or_path, $offset, $callback->($status)	676	=item aio_truncate $fh_or_path, $offset, $callback->($status)
607		677
608	Works like truncate(2) or ftruncate(2).	678	Works like truncate(2) or ftruncate(2).
609		679
610		680
		681	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		682
		683	Allocates or frees disk space according to the C<$mode> argument. See the
		684	linux C<fallocate> documentation for details.
		685
		686	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		687	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		688	to deallocate a file range.
		689
		690	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		691	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		692	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		693	to unshare shared blocks (see your L<fallocate(2)> manpage).
		694
		695	The file system block size used by C<fallocate> is presumably the
		696	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		697	can dictate other limitations.
		698
		699	If C<fallocate> isn't available or cannot be emulated (currently no
		700	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		701
		702
611	=item aio_chmod $fh_or_path, $mode, $callback->($status)	703	=item aio_chmod $fh_or_path, $mode, $callback->($status)
612		704
613	Works like perl's C<chmod> function.	705	Works like perl's C<chmod> function.
614		706
615		707
…		…
652		744
653		745
654	=item aio_realpath $pathname, $callback->($path)	746	=item aio_realpath $pathname, $callback->($path)
655		747
656	Asynchronously make the path absolute and resolve any symlinks in	748	Asynchronously make the path absolute and resolve any symlinks in
657	C<$path>. The resulting path only consists of directories (Same as	749	C<$path>. The resulting path only consists of directories (same as
658	L<Cwd::realpath>).	750	L<Cwd::realpath>).
659		751
660	This request can be used to get the absolute path of the current working	752	This request can be used to get the absolute path of the current working
661	directory by passing it a path of F<.> (a single dot).	753	directory by passing it a path of F<.> (a single dot).
662		754
663		755
664	=item aio_rename $srcpath, $dstpath, $callback->($status)	756	=item aio_rename $srcpath, $dstpath, $callback->($status)
665		757
666	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	758	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
667	rename(2) and call the callback with the result code.	759	rename(2) and call the callback with the result code.
		760
		761	On systems that support the AIO::WD working directory abstraction
		762	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		763	of failing, C<rename> is called on the absolute path of C<$wd>.
		764
		765
		766	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		767
		768	Basically a version of C<aio_rename> with an additional C<$flags>
		769	argument. Calling this with C<$flags=0> is the same as calling
		770	C<aio_rename>.
		771
		772	Non-zero flags are currently only supported on GNU/Linux systems that
		773	support renameat2. Other systems fail with C<ENOSYS> in this case.
		774
		775	The following constants are available (missing ones are, as usual C<0>),
		776	see renameat2(2) for details:
		777
		778	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		779	and C<IO::AIO::RENAME_WHITEOUT>.
668		780
669		781
670	=item aio_mkdir $pathname, $mode, $callback->($status)	782	=item aio_mkdir $pathname, $mode, $callback->($status)
671		783
672	Asynchronously mkdir (create) a directory and call the callback with	784	Asynchronously mkdir (create) a directory and call the callback with
…		…
677	=item aio_rmdir $pathname, $callback->($status)	789	=item aio_rmdir $pathname, $callback->($status)
678		790
679	Asynchronously rmdir (delete) a directory and call the callback with the	791	Asynchronously rmdir (delete) a directory and call the callback with the
680	result code.	792	result code.
681		793
		794	On systems that support the AIO::WD working directory abstraction
		795	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		796	C<rmdir> is called on the absolute path of C<$wd>.
		797
682		798
683	=item aio_readdir $pathname, $callback->($entries)	799	=item aio_readdir $pathname, $callback->($entries)
684		800
685	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	801	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
686	directory (i.e. opendir + readdir + closedir). The entries will not be	802	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
701		817
702	=over 4	818	=over 4
703		819
704	=item IO::AIO::READDIR_DENTS	820	=item IO::AIO::READDIR_DENTS
705		821
706	When this flag is off, then the callback gets an arrayref consisting of	822	Normally the callback gets an arrayref consisting of names only (as
707	names only (as with C<aio_readdir>), otherwise it gets an arrayref with	823	with C<aio_readdir>). If this flag is set, then the callback gets an
708	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	824	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
709	entry in more detail.	825	single directory entry in more detail:
710		826
711	C<$name> is the name of the entry.	827	C<$name> is the name of the entry.
712		828
713	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	829	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
714		830
715	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	831	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
716	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	832	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
717	C<IO::AIO::DT_WHT>.	833	C<IO::AIO::DT_WHT>.
718		834
719	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	835	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
720	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	836	to know, you have to run stat yourself. Also, for speed/memory reasons,
721	scalars are read-only: you can not modify them.	837	the C<$type> scalars are read-only: you must not modify them.
722		838
723	C<$inode> is the inode number (which might not be exact on systems with 64	839	C<$inode> is the inode number (which might not be exact on systems with 64
724	bit inode numbers and 32 bit perls). This field has unspecified content on	840	bit inode numbers and 32 bit perls). This field has unspecified content on
725	systems that do not deliver the inode information.	841	systems that do not deliver the inode information.
726		842
…		…
737	short names are tried first.	853	short names are tried first.
738		854
739	=item IO::AIO::READDIR_STAT_ORDER	855	=item IO::AIO::READDIR_STAT_ORDER
740		856
741	When this flag is set, then the names will be returned in an order	857	When this flag is set, then the names will be returned in an order
742	suitable for stat()'ing each one. That is, when you plan to stat()	858	suitable for stat()'ing each one. That is, when you plan to stat() most or
743	all files in the given directory, then the returned order will likely	859	all files in the given directory, then the returned order will likely be
744	be fastest.	860	faster.
745		861
746	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then	862	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
747	the likely dirs come first, resulting in a less optimal stat order.	863	then the likely dirs come first, resulting in a less optimal stat order
		864	for stat'ing all entries, but likely a more optimal order for finding
		865	subdirectories.
748		866
749	=item IO::AIO::READDIR_FOUND_UNKNOWN	867	=item IO::AIO::READDIR_FOUND_UNKNOWN
750		868
751	This flag should not be set when calling C<aio_readdirx>. Instead, it	869	This flag should not be set when calling C<aio_readdirx>. Instead, it
752	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	870	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
…		…
754	C<$type>'s are known, which can be used to speed up some algorithms.	872	C<$type>'s are known, which can be used to speed up some algorithms.
755		873
756	=back	874	=back
757		875
758		876
		877	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		878
		879	Opens, reads and closes the given file. The data is put into C<$data>,
		880	which is resized as required.
		881
		882	If C<$offset> is negative, then it is counted from the end of the file.
		883
		884	If C<$length> is zero, then the remaining length of the file is
		885	used. Also, in this case, the same limitations to modifying C<$data> apply
		886	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		887	with C<substr>. If the size of the file is known, specifying a non-zero
		888	C<$length> results in a performance advantage.
		889
		890	This request is similar to the older C<aio_load> request, but since it is
		891	a single request, it might be more efficient to use.
		892
		893	Example: load F</etc/passwd> into C<$passwd>.
		894
		895	my $passwd;
		896	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		897	$_[0] >= 0
		898	or die "/etc/passwd: $!\n";
		899
		900	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		901	print $passwd;
		902	};
		903	IO::AIO::flush;
		904
		905
759	=item aio_load $pathname, $data, $callback->($status)	906	=item aio_load $pathname, $data, $callback->($status)
760		907
761	This is a composite request that tries to fully load the given file into	908	This is a composite request that tries to fully load the given file into
762	memory. Status is the same as with aio_read.	909	memory. Status is the same as with aio_read.
		910
		911	Using C<aio_slurp> might be more efficient, as it is a single request.
763		912
764	=cut	913	=cut
765		914
766	sub aio_load($$;$) {	915	sub aio_load($$;$) {
767	my ($path, undef, $cb) = @_;	916	my ($path, undef, $cb) = @_;
…		…
787	=item aio_copy $srcpath, $dstpath, $callback->($status)	936	=item aio_copy $srcpath, $dstpath, $callback->($status)
788		937
789	Try to copy the I<file> (directories not supported as either source or	938	Try to copy the I<file> (directories not supported as either source or
790	destination) from C<$srcpath> to C<$dstpath> and call the callback with	939	destination) from C<$srcpath> to C<$dstpath> and call the callback with
791	a status of C<0> (ok) or C<-1> (error, see C<$!>).	940	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		941
		942	Existing destination files will be truncated.
792		943
793	This is a composite request that creates the destination file with	944	This is a composite request that creates the destination file with
794	mode 0200 and copies the contents of the source file into it using	945	mode 0200 and copies the contents of the source file into it using
795	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	946	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
796	uid/gid, in that order.	947	uid/gid, in that order.
…		…
906	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1057	Scans a directory (similar to C<aio_readdir>) but additionally tries to
907	efficiently separate the entries of directory C<$path> into two sets of	1058	efficiently separate the entries of directory C<$path> into two sets of
908	names, directories you can recurse into (directories), and ones you cannot	1059	names, directories you can recurse into (directories), and ones you cannot
909	recurse into (everything else, including symlinks to directories).	1060	recurse into (everything else, including symlinks to directories).
910		1061
911	C<aio_scandir> is a composite request that creates of many sub requests_	1062	C<aio_scandir> is a composite request that generates many sub requests.
912	C<$maxreq> specifies the maximum number of outstanding aio requests that	1063	C<$maxreq> specifies the maximum number of outstanding aio requests that
913	this function generates. If it is C<< <= 0 >>, then a suitable default	1064	this function generates. If it is C<< <= 0 >>, then a suitable default
914	will be chosen (currently 4).	1065	will be chosen (currently 4).
915		1066
916	On error, the callback is called without arguments, otherwise it receives	1067	On error, the callback is called without arguments, otherwise it receives
…		…
966		1117
967	my $grp = aio_group $cb;	1118	my $grp = aio_group $cb;
968		1119
969	$maxreq = 4 if $maxreq <= 0;	1120	$maxreq = 4 if $maxreq <= 0;
970		1121
971	# stat once	1122	# get a wd object
972	aioreq_pri $pri;	1123	aioreq_pri $pri;
973	add $grp aio_stat $path, sub {	1124	add $grp aio_wd $path, sub {
		1125	$_[0]
974	return $grp->result () if $_[0];	1126	or return $grp->result ();
975	my $now = time;
976	my $hash1 = join ":", (stat _)[0,1,3,7,9];
977		1127
978	# read the directory entries	1128	my $wd = [shift, "."];
		1129
		1130	# stat once
979	aioreq_pri $pri;	1131	aioreq_pri $pri;
980	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1132	add $grp aio_stat $wd, sub {
981	my $entries = shift
982	or return $grp->result ();	1133	return $grp->result () if $_[0];
		1134	my $now = time;
		1135	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		1136	my $rdxflags = READDIR_DIRS_FIRST;
983		1137
984	# stat the dir another time	1138	if ((stat _)[3] < 2) {
		1139	# at least one non-POSIX filesystem exists
		1140	# that returns useful DT_type values: btrfs,
		1141	# so optimise for this here by requesting dents
		1142	$rdxflags |= READDIR_DENTS;
		1143	}
		1144
		1145	# read the directory entries
985	aioreq_pri $pri;	1146	aioreq_pri $pri;
986	add $grp aio_stat $path, sub {	1147	add $grp aio_readdirx $wd, $rdxflags, sub {
987	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1148	my ($entries, $flags) = @_
		1149	or return $grp->result ();
988		1150
		1151	if ($rdxflags & READDIR_DENTS) {
		1152	# if we requested type values, see if we can use them directly.
		1153
		1154	# if there were any DT_UNKNOWN entries then we assume we
		1155	# don't know. alternatively, we could assume that if we get
		1156	# one DT_DIR, then all directories are indeed marked with
		1157	# DT_DIR, but this seems not required for btrfs, and this
		1158	# is basically the "btrfs can't get it's act together" code
		1159	# branch.
		1160	unless ($flags & READDIR_FOUND_UNKNOWN) {
		1161	# now we have valid DT_ information for all entries,
		1162	# so use it as an optimisation without further stat's.
		1163	# they must also all be at the beginning of @$entries
		1164	# by now.
		1165
989	my $ndirs;	1166	my $dirs;
990		1167
991	# take the slow route if anything looks fishy
992	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
993	$ndirs = -1;
994	} else {
995	# if nlink == 2, we are finished
996	# for non-posix-fs's, we rely on nlink < 2
997	$ndirs = (stat _)[3] - 2
998	or return $grp->result ([], $entries);
999	}
1000
1001	my (@dirs, @nondirs);
1002
1003	my $statgrp = add $grp aio_group sub {
1004	$grp->result (\@dirs, \@nondirs);
1005	};
1006
1007	limit $statgrp $maxreq;
1008	feed $statgrp sub {
1009	return unless @$entries;
1010	my $entry = shift @$entries;
1011
1012	aioreq_pri $pri;
1013	add $statgrp aio_stat "$path/$entry/.", sub {
1014	if ($_[0] < 0) {	1168	if (@$entries) {
1015	push @nondirs, $entry;	1169	for (0 .. $#$entries) {
1016	} else {	1170	if ($entries->[$_][1] != DT_DIR) {
1017	# need to check for real directory	1171	# splice out directories
1018	aioreq_pri $pri;	1172	$dirs = [splice @$entries, 0, $_];
1019	add $statgrp aio_lstat "$path/$entry", sub {
1020	if (-d _) {
1021	push @dirs, $entry;
1022
1023	unless (--$ndirs) {
1024	push @nondirs, @$entries;
1025	feed $statgrp;
1026	}	1173	last;
1027	} else {
1028	push @nondirs, $entry;
1029	}	1174	}
1030	}	1175	}
		1176
		1177	# if we didn't find any non-dir, then all entries are dirs
		1178	unless ($dirs) {
		1179	($dirs, $entries) = ($entries, []);
		1180	}
		1181	} else {
		1182	# directory is empty, so there are no sbdirs
		1183	$dirs = [];
1031	}	1184	}
		1185
		1186	# either splice'd the directories out or the dir was empty.
		1187	# convert dents to filenames
		1188	$_ = $_->[0] for @$dirs;
		1189	$_ = $_->[0] for @$entries;
		1190
		1191	return $grp->result ($dirs, $entries);
		1192	}
		1193
		1194	# cannot use, so return to our old ways
		1195	# by pretending we only scanned for names.
		1196	$_ = $_->[0] for @$entries;
		1197	}
		1198
		1199	# stat the dir another time
		1200	aioreq_pri $pri;
		1201	add $grp aio_stat $wd, sub {
		1202	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		1203
		1204	my $ndirs;
		1205
		1206	# take the slow route if anything looks fishy
		1207	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
		1208	$ndirs = -1;
		1209	} else {
		1210	# if nlink == 2, we are finished
		1211	# for non-posix-fs's, we rely on nlink < 2
		1212	$ndirs = (stat _)[3] - 2
		1213	or return $grp->result ([], $entries);
		1214	}
		1215
		1216	my (@dirs, @nondirs);
		1217
		1218	my $statgrp = add $grp aio_group sub {
		1219	$grp->result (\@dirs, \@nondirs);
		1220	};
		1221
		1222	limit $statgrp $maxreq;
		1223	feed $statgrp sub {
		1224	return unless @$entries;
		1225	my $entry = shift @$entries;
		1226
		1227	aioreq_pri $pri;
		1228	$wd->[1] = "$entry/.";
		1229	add $statgrp aio_stat $wd, sub {
		1230	if ($_[0] < 0) {
		1231	push @nondirs, $entry;
		1232	} else {
		1233	# need to check for real directory
		1234	aioreq_pri $pri;
		1235	$wd->[1] = $entry;
		1236	add $statgrp aio_lstat $wd, sub {
		1237	if (-d _) {
		1238	push @dirs, $entry;
		1239
		1240	unless (--$ndirs) {
		1241	push @nondirs, @$entries;
		1242	feed $statgrp;
		1243	}
		1244	} else {
		1245	push @nondirs, $entry;
		1246	}
		1247	}
		1248	}
		1249	};
1032	};	1250	};
1033	};	1251	};
1034	};	1252	};
1035	};	1253	};
1036	};	1254	};
…		…
1039	}	1257	}
1040		1258
1041	=item aio_rmtree $pathname, $callback->($status)	1259	=item aio_rmtree $pathname, $callback->($status)
1042		1260
1043	Delete a directory tree starting (and including) C<$path>, return the	1261	Delete a directory tree starting (and including) C<$path>, return the
1044	status of the final C<rmdir> only. This is a composite request that	1262	status of the final C<rmdir> only. This is a composite request that
1045	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1263	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1046	everything else.	1264	everything else.
1047		1265
1048	=cut	1266	=cut
1049		1267
…		…
1070	add $grp $dirgrp;	1288	add $grp $dirgrp;
1071	};	1289	};
1072		1290
1073	$grp	1291	$grp
1074	}	1292	}
		1293
		1294	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1295
		1296	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1297
		1298	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1299	they execute asynchronously and pass the return value to the callback.
		1300
		1301	Both calls can be used for a lot of things, some of which make more sense
		1302	to run asynchronously in their own thread, while some others make less
		1303	sense. For example, calls that block waiting for external events, such
		1304	as locking, will also lock down an I/O thread while it is waiting, which
		1305	can deadlock the whole I/O system. At the same time, there might be no
		1306	alternative to using a thread to wait.
		1307
		1308	So in general, you should only use these calls for things that do
		1309	(filesystem) I/O, not for things that wait for other events (network,
		1310	other processes), although if you are careful and know what you are doing,
		1311	you still can.
		1312
		1313	The following constants are available and can be used for normal C<ioctl>
		1314	and C<fcntl> as well (missing ones are, as usual C<0>):
		1315
		1316	C<F_DUPFD_CLOEXEC>,
		1317
		1318	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1319
		1320	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1321
		1322	C<F_ADD_SEALS>, C<F_GET_SEALS>, C<F_SEAL_SEAL>, C<F_SEAL_SHRINK>, C<F_SEAL_GROW> and
		1323	C<F_SEAL_WRITE>.
		1324
		1325	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1326	C<FS_IOC_FIEMAP>.
		1327
		1328	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1329	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1330
		1331	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1332	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1333	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1334	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1335	C<FS_FL_USER_MODIFIABLE>.
		1336
		1337	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1338	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1339	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1340	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
1075		1341
1076	=item aio_sync $callback->($status)	1342	=item aio_sync $callback->($status)
1077		1343
1078	Asynchronously call sync and call the callback when finished.	1344	Asynchronously call sync and call the callback when finished.
1079		1345
…		…
1148	};	1414	};
1149		1415
1150	$grp	1416	$grp
1151	}	1417	}
1152		1418
1153	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1419	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1154		1420
1155	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1421	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1156	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1422	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1157	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1423	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1158	scalar must only be modified in-place while an aio operation is pending on	1424	scalar must only be modified in-place while an aio operation is pending on
…		…
1160		1426
1161	It calls the C<msync> function of your OS, if available, with the memory	1427	It calls the C<msync> function of your OS, if available, with the memory
1162	area starting at C<$offset> in the string and ending C<$length> bytes	1428	area starting at C<$offset> in the string and ending C<$length> bytes
1163	later. If C<$length> is negative, counts from the end, and if C<$length>	1429	later. If C<$length> is negative, counts from the end, and if C<$length>
1164	is C<undef>, then it goes till the end of the string. The flags can be	1430	is C<undef>, then it goes till the end of the string. The flags can be
1165	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1431	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1166	C<IO::AIO::MS_SYNC>.	1432	C<IO::AIO::MS_INVALIDATE>.
1167		1433
1168	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1434	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1169		1435
1170	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1436	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1171	scalars.	1437	scalars.
1172		1438
1173	It touches (reads or writes) all memory pages in the specified	1439	It touches (reads or writes) all memory pages in the specified
1174	range inside the scalar. All caveats and parameters are the same	1440	range inside the scalar. All caveats and parameters are the same
1175	as for C<aio_msync>, above, except for flags, which must be either	1441	as for C<aio_msync>, above, except for flags, which must be either
1176	C<0> (which reads all pages and ensures they are instantiated) or	1442	C<0> (which reads all pages and ensures they are instantiated) or
1177	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1443	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1178	writing an octet from it, which dirties the page).	1444	writing an octet from it, which dirties the page).
1179		1445
1180	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1446	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1181		1447
1182	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1448	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1201	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;	1467	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1202	aio_mlock $data; # mlock in background	1468	aio_mlock $data; # mlock in background
1203		1469
1204	=item aio_mlockall $flags, $callback->($status)	1470	=item aio_mlockall $flags, $callback->($status)
1205		1471
1206	Calls the C<mlockall> function with the given C<$flags> (a combination of	1472	Calls the C<mlockall> function with the given C<$flags> (a
1207	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).	1473	combination of C<IO::AIO::MCL_CURRENT>, C<IO::AIO::MCL_FUTURE> and
		1474	C<IO::AIO::MCL_ONFAULT>).
1208		1475
1209	On systems that do not implement C<mlockall>, this function returns C<-1>	1476	On systems that do not implement C<mlockall>, this function returns C<-1>
1210	and sets errno to C<ENOSYS>.	1477	and sets errno to C<ENOSYS>. Similarly, flag combinations not supported
		1478	by the system result in a return value of C<-1> with errno being set to
		1479	C<EINVAL>.
1211		1480
1212	Note that the corresponding C<munlockall> is synchronous and is	1481	Note that the corresponding C<munlockall> is synchronous and is
1213	documented under L<MISCELLANEOUS FUNCTIONS>.	1482	documented under L<MISCELLANEOUS FUNCTIONS>.
1214		1483
1215	Example: asynchronously lock all current and future pages into memory.	1484	Example: asynchronously lock all current and future pages into memory.
1216		1485
1217	aio_mlockall IO::AIO::MCL_FUTURE;	1486	aio_mlockall IO::AIO::MCL_FUTURE;
		1487
		1488	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1489
		1490	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1491	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1492	the ioctl is not available on your OS, then this request will fail with
		1493	C<ENOSYS>.
		1494
		1495	C<$start> is the starting offset to query extents for, C<$length> is the
		1496	size of the range to query - if it is C<undef>, then the whole file will
		1497	be queried.
		1498
		1499	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1500	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1501	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1502	the data portion.
		1503
		1504	C<$count> is the maximum number of extent records to return. If it is
		1505	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1506	case, if it is C<0>, then the callback receives the number of extents
		1507	instead of the extents themselves (which is unreliable, see below).
		1508
		1509	If an error occurs, the callback receives no arguments. The special
		1510	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1511
		1512	Otherwise, the callback receives an array reference with extent
		1513	structures. Each extent structure is an array reference itself, with the
		1514	following members:
		1515
		1516	[$logical, $physical, $length, $flags]
		1517
		1518	Flags is any combination of the following flag values (typically either C<0>
		1519	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1520
		1521	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1522	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1523	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1524	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1525	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1526	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1527
		1528	At the time of this writing (Linux 3.2), this request is unreliable unless
		1529	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1530	it to return all extents of a range for files with a large number of
		1531	extents. The code (only) works around all these issues if C<$count> is
		1532	C<undef>.
1218		1533
1219	=item aio_group $callback->(...)	1534	=item aio_group $callback->(...)
1220		1535
1221	This is a very special aio request: Instead of doing something, it is a	1536	This is a very special aio request: Instead of doing something, it is a
1222	container for other aio requests, which is useful if you want to bundle	1537	container for other aio requests, which is useful if you want to bundle
…		…
1286	object. This object stores the canonicalised, absolute version of the	1601	object. This object stores the canonicalised, absolute version of the
1287	path, and on systems that allow it, also a directory file descriptor.	1602	path, and on systems that allow it, also a directory file descriptor.
1288		1603
1289	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>	1604	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1290	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD	1605	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1291	object and a pathname instead. If the pathname is absolute, the	1606	object and a pathname instead (or the IO::AIO::WD object alone, which
		1607	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1292	IO::AIO::WD objetc is ignored, otherwise the pathname is resolved relative	1608	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1293	to that IO::AIO::WD object.	1609	to that IO::AIO::WD object.
1294		1610
1295	For example, to get a wd object for F</etc> and then stat F<passwd>	1611	For example, to get a wd object for F</etc> and then stat F<passwd>
1296	inside, you would write:	1612	inside, you would write:
1297		1613
…		…
1305	aio_stat [$etcdir, "passwd"], sub {	1621	aio_stat [$etcdir, "passwd"], sub {
1306	# yay	1622	# yay
1307	};	1623	};
1308	};	1624	};
1309		1625
		1626	The fact that C<aio_wd> is a request and not a normal function shows that
1310	This shows that creating an IO::AIO::WD object is itself a potentially	1627	creating an IO::AIO::WD object is itself a potentially blocking operation,
1311	blocking operation, which is why it is done asynchronously.	1628	which is why it is done asynchronously.
		1629
		1630	To stat the directory obtained with C<aio_wd> above, one could write
		1631	either of the following three request calls:
		1632
		1633	aio_lstat "/etc" , sub { ... # pathname as normal string
		1634	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1635	aio_lstat $wd , sub { ... # shorthand for the previous
1312		1636
1313	As with normal pathnames, IO::AIO keeps a copy of the working directory	1637	As with normal pathnames, IO::AIO keeps a copy of the working directory
1314	object and the pathname string, so you could write the following without	1638	object and the pathname string, so you could write the following without
1315	causing any issues due to C<$path> getting reused:	1639	causing any issues due to C<$path> getting reused:
1316		1640
…		…
1326	There are some caveats: when directories get renamed (or deleted), the	1650	There are some caveats: when directories get renamed (or deleted), the
1327	pathname string doesn't change, so will point to the new directory (or	1651	pathname string doesn't change, so will point to the new directory (or
1328	nowhere at all), while the directory fd, if available on the system,	1652	nowhere at all), while the directory fd, if available on the system,
1329	will still point to the original directory. Most functions accepting a	1653	will still point to the original directory. Most functions accepting a
1330	pathname will use the directory fd on newer systems, and the string on	1654	pathname will use the directory fd on newer systems, and the string on
1331	older systems. Some functions (such as realpath) will always rely on the	1655	older systems. Some functions (such as C<aio_realpath>) will always rely on
1332	string form of the pathname.	1656	the string form of the pathname.
1333		1657
1334	So this fucntionality is mainly useful to get some protection against	1658	So this functionality is mainly useful to get some protection against
1335	C<chdir>, to easily get an absolute path out of a relative path for future	1659	C<chdir>, to easily get an absolute path out of a relative path for future
1336	reference, and to speed up doing many operations in the same directory	1660	reference, and to speed up doing many operations in the same directory
1337	(e.g. when stat'ing all files in a directory).	1661	(e.g. when stat'ing all files in a directory).
1338		1662
1339	The following functions implement this working directory abstraction:	1663	The following functions implement this working directory abstraction:
…		…
1352	passing C<undef> as working directory component of a pathname fails the	1676	passing C<undef> as working directory component of a pathname fails the
1353	request with C<ENOENT>, there is often no need for error checking in the	1677	request with C<ENOENT>, there is often no need for error checking in the
1354	C<aio_wd> callback, as future requests using the value will fail in the	1678	C<aio_wd> callback, as future requests using the value will fail in the
1355	expected way.	1679	expected way.
1356		1680
1357	If this call isn't available because your OS lacks it or it couldn't be
1358	detected, it will be emulated by calling C<fsync> instead.
1359
1360	=item IO::AIO::CWD	1681	=item IO::AIO::CWD
1361		1682
1362	This is a compiletime constant (object) that represents the process	1683	This is a compiletime constant (object) that represents the process
1363	current working directory.	1684	current working directory.
1364		1685
1365	Specifying this object as working directory object for a pathname is as	1686	Specifying this object as working directory object for a pathname is as if
1366	if the pathname would be specified directly, without a directory object,	1687	the pathname would be specified directly, without a directory object. For
1367	e.g., these calls are functionally identical:	1688	example, these calls are functionally identical:
1368		1689
1369	aio_stat "somefile", sub { ... };	1690	aio_stat "somefile", sub { ... };
1370	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };	1691	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1371		1692
1372	=back	1693	=back
1373		1694
		1695	To recover the path associated with an IO::AIO::WD object, you can use
		1696	C<aio_realpath>:
		1697
		1698	aio_realpath $wd, sub {
		1699	warn "path is $_[0]\n";
		1700	};
		1701
		1702	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1703	sometimes, fall back to using an absolue path.
1374		1704
1375	=head2 IO::AIO::REQ CLASS	1705	=head2 IO::AIO::REQ CLASS
1376		1706
1377	All non-aggregate C<aio_*> functions return an object of this class when	1707	All non-aggregate C<aio_*> functions return an object of this class when
1378	called in non-void context.	1708	called in non-void context.
…		…
1496		1826
1497	Sets a feeder/generator on this group: every group can have an attached	1827	Sets a feeder/generator on this group: every group can have an attached
1498	generator that generates requests if idle. The idea behind this is that,	1828	generator that generates requests if idle. The idea behind this is that,
1499	although you could just queue as many requests as you want in a group,	1829	although you could just queue as many requests as you want in a group,
1500	this might starve other requests for a potentially long time. For example,	1830	this might starve other requests for a potentially long time. For example,
1501	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1831	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1502	delaying any later requests for a long time.	1832	requests, delaying any later requests for a long time.
1503		1833
1504	To avoid this, and allow incremental generation of requests, you can	1834	To avoid this, and allow incremental generation of requests, you can
1505	instead a group and set a feeder on it that generates those requests. The	1835	instead a group and set a feeder on it that generates those requests. The
1506	feed callback will be called whenever there are few enough (see C<limit>,	1836	feed callback will be called whenever there are few enough (see C<limit>,
1507	below) requests active in the group itself and is expected to queue more	1837	below) requests active in the group itself and is expected to queue more
…		…
1539	The default value for the limit is C<0>, but note that setting a feeder	1869	The default value for the limit is C<0>, but note that setting a feeder
1540	automatically bumps it up to C<2>.	1870	automatically bumps it up to C<2>.
1541		1871
1542	=back	1872	=back
1543		1873
		1874
1544	=head2 SUPPORT FUNCTIONS	1875	=head2 SUPPORT FUNCTIONS
1545		1876
1546	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1877	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1547		1878
1548	=over 4	1879	=over 4
…		…
1556		1887
1557	See C<poll_cb> for an example.	1888	See C<poll_cb> for an example.
1558		1889
1559	=item IO::AIO::poll_cb	1890	=item IO::AIO::poll_cb
1560		1891
1561	Process some outstanding events on the result pipe. You have to call	1892	Process some requests that have reached the result phase (i.e. they have
		1893	been executed but the results are not yet reported). You have to call
		1894	this "regularly" to finish outstanding requests.
		1895
1562	this regularly. Returns C<0> if all events could be processed (or there	1896	Returns C<0> if all events could be processed (or there were no
1563	were no events to process), or C<-1> if it returned earlier for whatever	1897	events to process), or C<-1> if it returned earlier for whatever
1564	reason. Returns immediately when no events are outstanding. The amount of	1898	reason. Returns immediately when no events are outstanding. The amount
1565	events processed depends on the settings of C<IO::AIO::max_poll_req> and	1899	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1566	C<IO::AIO::max_poll_time>.	1900	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1567		1901
1568	If not all requests were processed for whatever reason, the filehandle	1902	If not all requests were processed for whatever reason, the poll file
1569	will still be ready when C<poll_cb> returns, so normally you don't have to	1903	descriptor will still be ready when C<poll_cb> returns, so normally you
1570	do anything special to have it called later.	1904	don't have to do anything special to have it called later.
1571		1905
1572	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1906	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1573	ready, it can be beneficial to call this function from loops which submit	1907	ready, it can be beneficial to call this function from loops which submit
1574	a lot of requests, to make sure the results get processed when they become	1908	a lot of requests, to make sure the results get processed when they become
1575	available and not just when the loop is finished and the event loop takes	1909	available and not just when the loop is finished and the event loop takes
…		…
1584	poll => 'r', async => 1,	1918	poll => 'r', async => 1,
1585	cb => \&IO::AIO::poll_cb);	1919	cb => \&IO::AIO::poll_cb);
1586		1920
1587	=item IO::AIO::poll_wait	1921	=item IO::AIO::poll_wait
1588		1922
1589	If there are any outstanding requests and none of them in the result	1923	Wait until either at least one request is in the result phase or no
1590	phase, wait till the result filehandle becomes ready for reading (simply	1924	requests are outstanding anymore.
1591	does a C<select> on the filehandle. This is useful if you want to	1925
1592	synchronously wait for some requests to finish).	1926	This is useful if you want to synchronously wait for some requests to
		1927	become ready, without actually handling them.
1593		1928
1594	See C<nreqs> for an example.	1929	See C<nreqs> for an example.
1595		1930
1596	=item IO::AIO::poll	1931	=item IO::AIO::poll
1597		1932
…		…
1608		1943
1609	Strictly equivalent to:	1944	Strictly equivalent to:
1610		1945
1611	IO::AIO::poll_wait, IO::AIO::poll_cb	1946	IO::AIO::poll_wait, IO::AIO::poll_cb
1612	while IO::AIO::nreqs;	1947	while IO::AIO::nreqs;
		1948
		1949	This function can be useful at program aborts, to make sure outstanding
		1950	I/O has been done (C<IO::AIO> uses an C<END> block which already calls
		1951	this function on normal exits), or when you are merely using C<IO::AIO>
		1952	for its more advanced functions, rather than for async I/O, e.g.:
		1953
		1954	my ($dirs, $nondirs);
		1955	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1956	IO::AIO::flush;
		1957	# $dirs, $nondirs are now set
1613		1958
1614	=item IO::AIO::max_poll_reqs $nreqs	1959	=item IO::AIO::max_poll_reqs $nreqs
1615		1960
1616	=item IO::AIO::max_poll_time $seconds	1961	=item IO::AIO::max_poll_time $seconds
1617		1962
…		…
1644	poll => 'r', nice => 1,	1989	poll => 'r', nice => 1,
1645	cb => &IO::AIO::poll_cb);	1990	cb => &IO::AIO::poll_cb);
1646		1991
1647	=back	1992	=back
1648		1993
		1994
1649	=head3 CONTROLLING THE NUMBER OF THREADS	1995	=head3 CONTROLLING THE NUMBER OF THREADS
1650		1996
1651	=over	1997	=over
1652		1998
1653	=item IO::AIO::min_parallel $nthreads	1999	=item IO::AIO::min_parallel $nthreads
…		…
1718		2064
1719	This is a very bad function to use in interactive programs because it	2065	This is a very bad function to use in interactive programs because it
1720	blocks, and a bad way to reduce concurrency because it is inexact: Better	2066	blocks, and a bad way to reduce concurrency because it is inexact: Better
1721	use an C<aio_group> together with a feed callback.	2067	use an C<aio_group> together with a feed callback.
1722		2068
1723	It's main use is in scripts without an event loop - when you want to stat	2069	Its main use is in scripts without an event loop - when you want to stat
1724	a lot of files, you can write somehting like this:	2070	a lot of files, you can write something like this:
1725		2071
1726	IO::AIO::max_outstanding 32;	2072	IO::AIO::max_outstanding 32;
1727		2073
1728	for my $path (...) {	2074	for my $path (...) {
1729	aio_stat $path , ...;	2075	aio_stat $path , ...;
…		…
1740	The default value for C<max_outstanding> is very large, so there is no	2086	The default value for C<max_outstanding> is very large, so there is no
1741	practical limit on the number of outstanding requests.	2087	practical limit on the number of outstanding requests.
1742		2088
1743	=back	2089	=back
1744		2090
		2091
1745	=head3 STATISTICAL INFORMATION	2092	=head3 STATISTICAL INFORMATION
1746		2093
1747	=over	2094	=over
1748		2095
1749	=item IO::AIO::nreqs	2096	=item IO::AIO::nreqs
…		…
1766	Returns the number of requests currently in the pending state (executed,	2113	Returns the number of requests currently in the pending state (executed,
1767	but not yet processed by poll_cb).	2114	but not yet processed by poll_cb).
1768		2115
1769	=back	2116	=back
1770		2117
		2118
		2119	=head3 SUBSECOND STAT TIME ACCESS
		2120
		2121	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2122	generally find access/modification and change times with subsecond time
		2123	accuracy of the system supports it, but perl's built-in functions only
		2124	return the integer part.
		2125
		2126	The following functions return the timestamps of the most recent
		2127	stat with subsecond precision on most systems and work both after
		2128	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2129	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2130	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2131
		2132	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2133	full resolution without rounding and work with standard perl C<stat>,
		2134	alleviating the need to call the special C<Time::HiRes> functions, which
		2135	do not act like their perl counterparts.
		2136
		2137	On operating systems or file systems where subsecond time resolution is
		2138	not supported or could not be detected, a fractional part of C<0> is
		2139	returned, so it is always safe to call these functions.
		2140
		2141	=over 4
		2142
		2143	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		2144
		2145	Return the access, modication, change or birth time, respectively,
		2146	including fractional part. Due to the limited precision of floating point,
		2147	the accuracy on most platforms is only a bit better than milliseconds
		2148	for times around now - see the I<nsec> function family, below, for full
		2149	accuracy.
		2150
		2151	File birth time is only available when the OS and perl support it (on
		2152	FreeBSD and NetBSD at the time of this writing, although support is
		2153	adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
		2154	it). On systems where it isn't available, C<0> is currently returned, but
		2155	this might change to C<undef> in a future version.
		2156
		2157	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		2158
		2159	Returns access, modification, change and birth time all in one go, and
		2160	maybe more times in the future version.
		2161
		2162	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		2163
		2164	Return the fractional access, modifcation, change or birth time, in nanoseconds,
		2165	as an integer in the range C<0> to C<999999999>.
		2166
		2167	Note that no accessors are provided for access, modification and
		2168	change times - you need to get those from C<stat _> if required (C<int
		2169	IO::AIO::st_atime> and so on will I<not> generally give you the correct
		2170	value).
		2171
		2172	=item $seconds = IO::AIO::st_btimesec
		2173
		2174	The (integral) seconds part of the file birth time, if available.
		2175
		2176	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		2177
		2178	Like the functions above, but returns all four times in one go (and maybe
		2179	more in future versions).
		2180
		2181	=item $counter = IO::AIO::st_gen
		2182
		2183	Returns the generation counter (in practice this is just a random number)
		2184	of the file. This is only available on platforms which have this member in
		2185	their C<struct stat> (most BSDs at the time of this writing) and generally
		2186	only to the root usert. If unsupported, C<0> is returned, but this might
		2187	change to C<undef> in a future version.
		2188
		2189	=back
		2190
		2191	Example: print the high resolution modification time of F</etc>, using
		2192	C<stat>, and C<IO::AIO::aio_stat>.
		2193
		2194	if (stat "/etc") {
		2195	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2196	}
		2197
		2198	IO::AIO::aio_stat "/etc", sub {
		2199	$_[0]
		2200	and return;
		2201
		2202	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2203	};
		2204
		2205	IO::AIO::flush;
		2206
		2207	Output of the awbove on my system, showing reduced and full accuracy:
		2208
		2209	stat(/etc) mtime: 1534043702.020808
		2210	aio_stat(/etc) mtime: 1534043702.020807792
		2211
		2212
1771	=head3 MISCELLANEOUS FUNCTIONS	2213	=head3 MISCELLANEOUS FUNCTIONS
1772		2214
1773	IO::AIO implements some functions that might be useful, but are not	2215	IO::AIO implements some functions that are useful when you want to use
1774	asynchronous.	2216	some "Advanced I/O" function not available to in Perl, without going the
		2217	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2218	counterpart.
1775		2219
1776	=over 4	2220	=over 4
		2221
		2222	=item $numfd = IO::AIO::get_fdlimit
		2223
		2224	This function is I<EXPERIMENTAL> and subject to change.
		2225
		2226	Tries to find the current file descriptor limit and returns it, or
		2227	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2228	the highest valid file descriptor number.
		2229
		2230	=item IO::AIO::min_fdlimit [$numfd]
		2231
		2232	This function is I<EXPERIMENTAL> and subject to change.
		2233
		2234	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2235	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2236	is missing, it will try to set a very high limit, although this is not
		2237	recommended when you know the actual minimum that you require.
		2238
		2239	If the limit cannot be raised enough, the function makes a best-effort
		2240	attempt to increase the limit as much as possible, using various
		2241	tricks, while still failing. You can query the resulting limit using
		2242	C<IO::AIO::get_fdlimit>.
		2243
		2244	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2245	true.
1777		2246
1778	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2247	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1779		2248
1780	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2249	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1781	but is blocking (this makes most sense if you know the input data is	2250	but is blocking (this makes most sense if you know the input data is
…		…
1798	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2267	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1799		2268
1800	Simply calls the C<posix_madvise> function (see its	2269	Simply calls the C<posix_madvise> function (see its
1801	manpage for details). The following advice constants are	2270	manpage for details). The following advice constants are
1802	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2271	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1803	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2272	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2273	C<IO::AIO::MADV_DONTNEED>.
		2274
		2275	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2276	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2277	will be reduced to fit into the C<$scalar>.
1804		2278
1805	On systems that do not implement C<posix_madvise>, this function returns	2279	On systems that do not implement C<posix_madvise>, this function returns
1806	ENOSYS, otherwise the return value of C<posix_madvise>.	2280	ENOSYS, otherwise the return value of C<posix_madvise>.
1807		2281
1808	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2282	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
…		…
1810	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2284	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1811	$scalar (see its manpage for details). The following protect	2285	$scalar (see its manpage for details). The following protect
1812	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2286	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1813	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2287	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1814		2288
		2289	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2290	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2291	will be reduced to fit into the C<$scalar>.
		2292
1815	On systems that do not implement C<mprotect>, this function returns	2293	On systems that do not implement C<mprotect>, this function returns
1816	ENOSYS, otherwise the return value of C<mprotect>.	2294	ENOSYS, otherwise the return value of C<mprotect>.
1817		2295
1818	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2296	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1819		2297
1820	Memory-maps a file (or anonymous memory range) and attaches it to the	2298	Memory-maps a file (or anonymous memory range) and attaches it to the
1821	given C<$scalar>, which will act like a string scalar.	2299	given C<$scalar>, which will act like a string scalar. Returns true on
		2300	success, and false otherwise.
1822		2301
		2302	The scalar must exist, but its contents do not matter - this means you
		2303	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2304	the scalar first.
		2305
1823	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2306	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1824	change the string length, and most read-only operations such as copying it	2307	which don't change the string length, and most read-only operations such
1825	or searching it with regexes and so on.	2308	as copying it or searching it with regexes and so on.
1826		2309
1827	Anything else is unsafe and will, at best, result in memory leaks.	2310	Anything else is unsafe and will, at best, result in memory leaks.
1828		2311
1829	The memory map associated with the C<$scalar> is automatically removed	2312	The memory map associated with the C<$scalar> is automatically removed
1830	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2313	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1831	C<IO::AIO::munmap> functions are called.	2314	or C<IO::AIO::munmap> functions are called on it.
1832		2315
1833	This calls the C<mmap>(2) function internally. See your system's manual	2316	This calls the C<mmap>(2) function internally. See your system's manual
1834	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2317	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1835		2318
1836	The C<$length> must be larger than zero and smaller than the actual	2319	The C<$length> must be larger than zero and smaller than the actual
1837	filesize.	2320	filesize.
1838		2321
1839	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2322	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1840	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2323	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1841		2324
1842	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2325	C<$flags> can be a combination of
1843	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2326	C<IO::AIO::MAP_SHARED> or
1844	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2327	C<IO::AIO::MAP_PRIVATE>,
		2328	or a number of system-specific flags (when not available, the are C<0>):
1845	(which is set to C<MAP_ANON> if your system only provides this	2329	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1846	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2330	C<IO::AIO::MAP_LOCKED>,
1847	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2331	C<IO::AIO::MAP_NORESERVE>,
		2332	C<IO::AIO::MAP_POPULATE>,
1848	C<IO::AIO::MAP_NONBLOCK>	2333	C<IO::AIO::MAP_NONBLOCK>,
		2334	C<IO::AIO::MAP_FIXED>,
		2335	C<IO::AIO::MAP_GROWSDOWN>,
		2336	C<IO::AIO::MAP_32BIT>,
		2337	C<IO::AIO::MAP_HUGETLB> or
		2338	C<IO::AIO::MAP_STACK>.
1849		2339
1850	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2340	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1851		2341
1852	C<$offset> is the offset from the start of the file - it generally must be	2342	C<$offset> is the offset from the start of the file - it generally must be
1853	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2343	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1867		2357
1868	=item IO::AIO::munmap $scalar	2358	=item IO::AIO::munmap $scalar
1869		2359
1870	Removes a previous mmap and undefines the C<$scalar>.	2360	Removes a previous mmap and undefines the C<$scalar>.
1871		2361
		2362	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2363
		2364	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2365	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2366	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2367
		2368	Returns true if successful, and false otherwise. If the underlying mmapped
		2369	region has changed address, then the true value has the numerical value
		2370	C<1>, otherwise it has the numerical value C<0>:
		2371
		2372	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2373	or die "mremap: $!";
		2374
		2375	if ($success*1) {
		2376	warn "scalar has chanegd address in memory\n";
		2377	}
		2378
		2379	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2380	implemented, but not supported and might go away in a future version.
		2381
		2382	On systems where this call is not supported or is not emulated, this call
		2383	returns falls and sets C<$!> to C<ENOSYS>.
		2384
		2385	=item IO::AIO::mlockall $flags
		2386
		2387	Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
		2388	but is blocking.
		2389
1872	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef	2390	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1873		2391
1874	Calls the C<munlock> function, undoing the effects of a previous	2392	Calls the C<munlock> function, undoing the effects of a previous
1875	C<aio_mlock> call (see its description for details).	2393	C<aio_mlock> call (see its description for details).
1876		2394
…		…
1878		2396
1879	Calls the C<munlockall> function.	2397	Calls the C<munlockall> function.
1880		2398
1881	On systems that do not implement C<munlockall>, this function returns	2399	On systems that do not implement C<munlockall>, this function returns
1882	ENOSYS, otherwise the return value of C<munlockall>.	2400	ENOSYS, otherwise the return value of C<munlockall>.
		2401
		2402	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2403
		2404	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2405	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2406	should be the file offset.
		2407
		2408	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2409	silently corrupt the data in this case.
		2410
		2411	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2412	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2413	C<IO::AIO::SPLICE_F_GIFT>.
		2414
		2415	See the C<splice(2)> manpage for details.
		2416
		2417	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2418
		2419	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2420	description for C<IO::AIO::splice> above for details.
		2421
		2422	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2423
		2424	Attempts to query or change the pipe buffer size. Obviously works only
		2425	on pipes, and currently works only on GNU/Linux systems, and fails with
		2426	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2427	size on other systems, drop me a note.
		2428
		2429	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2430
		2431	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2432	C<$flags> is missing or C<0>, then this should be the same as a call to
		2433	perl's built-in C<pipe> function and create a new pipe, and works on
		2434	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2435	(..., 4096, O_BINARY)>.
		2436
		2437	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2438	the given flags (Linux 2.6.27, glibc 2.9).
		2439
		2440	On success, the read and write file handles are returned.
		2441
		2442	On error, nothing will be returned. If the pipe2 syscall is missing and
		2443	C<$flags> is non-zero, fails with C<ENOSYS>.
		2444
		2445	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2446	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2447	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2448
		2449	Example: create a pipe race-free w.r.t. threads and fork:
		2450
		2451	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2452	or die "pipe2: $!\n";
		2453
		2454	=item $fh = IO::AIO::memfd_create $pathname[, $flags]
		2455
		2456	This is a direct interface to the Linux L<memfd_create(2)> system
		2457	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2458	should be C<IO::AIO::MFD_CLOEXEC>.
		2459
		2460	On success, the new memfd filehandle is returned, otherwise returns
		2461	C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
		2462
		2463	Please refer to L<memfd_create(2)> for more info on this call.
		2464
		2465	The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
		2466	C<IO::AIO::MFD_ALLOW_SEALING> and C<IO::AIO::MFD_HUGETLB>.
		2467
		2468	Example: create a new memfd.
		2469
		2470	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2471	or die "m,emfd_create: $!\n";
		2472	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2473
		2474	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2475	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2476
		2477	On success, the new eventfd filehandle is returned, otherwise returns
		2478	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2479
		2480	Please refer to L<eventfd(2)> for more info on this call.
		2481
		2482	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2483	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2484
		2485	Example: create a new eventfd filehandle:
		2486
		2487	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2488	or die "eventfd: $!\n";
		2489
		2490	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2491
		2492	This is a direct interface to the Linux L<timerfd_create(2)> system
		2493	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2494	should be C<IO::AIO::TFD_CLOEXEC>.
		2495
		2496	On success, the new timerfd filehandle is returned, otherwise returns
		2497	C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
		2498
		2499	Please refer to L<timerfd_create(2)> for more info on this call.
		2500
		2501	The following C<$clockid> values are
		2502	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2503	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2504	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2505	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2506
		2507	The following C<$flags> values are available (Linux
		2508	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2509
		2510	Example: create a new timerfd and set it to one-second repeated alarms,
		2511	then wait for two alarms:
		2512
		2513	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2514	or die "timerfd_create: $!\n";
		2515
		2516	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2517	or die "timerfd_settime: $!\n";
		2518
		2519	for (1..2) {
		2520	8 == sysread $fh, my $buf, 8
		2521	or die "timerfd read failure\n";
		2522
		2523	printf "number of expirations (likely 1): %d\n",
		2524	unpack "Q", $buf;
		2525	}
		2526
		2527	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2528
		2529	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2530	call. Please refer to its manpage for more info on this call.
		2531
		2532	The new itimerspec is specified using two (possibly fractional) second
		2533	values, C<$new_interval> and C<$new_value>).
		2534
		2535	On success, the current interval and value are returned (as per
		2536	C<timerfd_gettime>). On failure, the empty list is returned.
		2537
		2538	The following C<$flags> values are
		2539	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2540	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2541
		2542	See C<IO::AIO::timerfd_create> for a full example.
		2543
		2544	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2545
		2546	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2547	call. Please refer to its manpage for more info on this call.
		2548
		2549	On success, returns the current values of interval and value for the given
		2550	timerfd (as potentially fractional second values). On failure, the empty
		2551	list is returned.
1883		2552
1884	=back	2553	=back
1885		2554
1886	=cut	2555	=cut
1887		2556
…		…
1953	the process will result in undefined behaviour. Calling it at any time	2622	the process will result in undefined behaviour. Calling it at any time
1954	will also result in any undefined (by POSIX) behaviour.	2623	will also result in any undefined (by POSIX) behaviour.
1955		2624
1956	=back	2625	=back
1957		2626
		2627	=head2 LINUX-SPECIFIC CALLS
		2628
		2629	When a call is documented as "linux-specific" then this means it
		2630	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2631	availability and compatibility of such calls regardless of the platform
		2632	it is compiled on, so platforms such as FreeBSD which often implement
		2633	these calls will work. When in doubt, call them and see if they fail wth
		2634	C<ENOSYS>.
		2635
1958	=head2 MEMORY USAGE	2636	=head2 MEMORY USAGE
1959		2637
1960	Per-request usage:	2638	Per-request usage:
1961		2639
1962	Each aio request uses - depending on your architecture - around 100-200	2640	Each aio request uses - depending on your architecture - around 100-200
…		…
1974	temporary buffers, and each thread requires a stack and other data	2652	temporary buffers, and each thread requires a stack and other data
1975	structures (usually around 16k-128k, depending on the OS).	2653	structures (usually around 16k-128k, depending on the OS).
1976		2654
1977	=head1 KNOWN BUGS	2655	=head1 KNOWN BUGS
1978		2656
1979	Known bugs will be fixed in the next release.	2657	Known bugs will be fixed in the next release :)
		2658
		2659	=head1 KNOWN ISSUES
		2660
		2661	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2662	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2663	non-created hash slots or other scalars I didn't think of. It's best to
		2664	avoid such and either use scalar variables or making sure that the scalar
		2665	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2666
		2667	I am not sure anything can be done about this, so this is considered a
		2668	known issue, rather than a bug.
1980		2669
1981	=head1 SEE ALSO	2670	=head1 SEE ALSO
1982		2671
1983	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2672	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1984	more natural syntax.	2673	more natural syntax and L<IO::FDPass> for file descriptor passing.
1985		2674
1986	=head1 AUTHOR	2675	=head1 AUTHOR
1987		2676
1988	Marc Lehmann <schmorp@schmorp.de>	2677	Marc Lehmann <schmorp@schmorp.de>
1989	http://home.schmorp.de/	2678	http://home.schmorp.de/

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