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Revision 1.203 by root, Thu Jul 7 22:36:18 2011 UTC vs.
Revision 1.319 by root, Wed Sep 27 03:09:57 2023 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	IO::AIO - Asynchronous Input/Output	3	IO::AIO - Asynchronous/Advanced Input/Output
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
…		…
58	not well-supported or restricted (GNU/Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
59	files currently, for example), and they would only support aio_read and	59	files currently, for example), and they would only support aio_read and
60	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
61	using threads anyway.	61	using threads anyway.
62		62
		63	In addition to asynchronous I/O, this module also exports some rather
		64	arcane interfaces, such as C<madvise> or linux's C<splice> system call,
		65	which is why the C<A> in C<AIO> can also mean I<advanced>.
		66
63	Although the module will work in the presence of other (Perl-) threads,	67	Although the module will work in the presence of other (Perl-) threads,
64	it is currently not reentrant in any way, so use appropriate locking	68	it is currently not reentrant in any way, so use appropriate locking
65	yourself, always call C<poll_cb> from within the same thread, or never	69	yourself, always call C<poll_cb> from within the same thread, or never
66	call C<poll_cb> (or other C<aio_> functions) recursively.	70	call C<poll_cb> (or other C<aio_> functions) recursively.
67		71
68	=head2 EXAMPLE	72	=head2 EXAMPLE
69		73
70	This is a simple example that uses the EV module and loads	74	This is a simple example that uses the EV module and loads
71	F</etc/passwd> asynchronously:	75	F</etc/passwd> asynchronously:
72		76
73	use Fcntl;
74	use EV;	77	use EV;
75	use IO::AIO;	78	use IO::AIO;
76		79
77	# register the IO::AIO callback with EV	80	# register the IO::AIO callback with EV
78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	81	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
…		…
95		98
96	# file contents now in $contents	99	# file contents now in $contents
97	print $contents;	100	print $contents;
98		101
99	# exit event loop and program	102	# exit event loop and program
100	EV::unloop;	103	EV::break;
101	};	104	};
102	};	105	};
103		106
104	# possibly queue up other requests, or open GUI windows,	107	# possibly queue up other requests, or open GUI windows,
105	# check for sockets etc. etc.	108	# check for sockets etc. etc.
106		109
107	# process events as long as there are some:	110	# process events as long as there are some:
108	EV::loop;	111	EV::run;
109		112
110	=head1 REQUEST ANATOMY AND LIFETIME	113	=head1 REQUEST ANATOMY AND LIFETIME
111		114
112	Every C<aio_*> function creates a request. which is a C data structure not	115	Every C<aio_*> function creates a request. which is a C data structure not
113	directly visible to Perl.	116	directly visible to Perl.
…		…
168	use common::sense;	171	use common::sense;
169		172
170	use base 'Exporter';	173	use base 'Exporter';
171		174
172	BEGIN {	175	BEGIN {
173	our $VERSION = '3.93';	176	our $VERSION = 4.80;
174		177
175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	178	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx	179	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync aio_fsync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178	aio_fdatasync aio_sync_file_range aio_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
		189	aio_wd);
185		190
186	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	191	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
187	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	192	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
188	min_parallel max_parallel max_idle idle_timeout	193	min_parallel max_parallel max_idle idle_timeout
189	nreqs nready npending nthreads	194	nreqs nready npending nthreads
190	max_poll_time max_poll_reqs	195	max_poll_time max_poll_reqs
191	sendfile fadvise madvise	196	sendfile fadvise madvise
192	mmap munmap munlock munlockall);	197	mmap munmap mremap munlock munlockall
		198
		199	accept4 tee splice pipe2 pipesize
		200	fexecve mount umount memfd_create eventfd
		201	timerfd_create timerfd_settime timerfd_gettime
		202	pidfd_open pidfd_send_signal pidfd_getfd);
193		203
194	push @AIO_REQ, qw(aio_busy); # not exported	204	push @AIO_REQ, qw(aio_busy); # not exported
195		205
196	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	206	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
197		207
…		…
201		211
202	=head1 FUNCTIONS	212	=head1 FUNCTIONS
203		213
204	=head2 QUICK OVERVIEW	214	=head2 QUICK OVERVIEW
205		215
206	This section simply lists the prototypes of the most important functions	216	This section simply lists the prototypes most of the functions for
207	for quick reference. See the following sections for function-by-function	217	quick reference. See the following sections for function-by-function
208	documentation.	218	documentation.
209		219
		220	aio_wd $pathname, $callback->($wd)
210	aio_open $pathname, $flags, $mode, $callback->($fh)	221	aio_open $pathname, $flags, $mode, $callback->($fh)
211	aio_close $fh, $callback->($status)	222	aio_close $fh, $callback->($status)
		223	aio_seek $fh,$offset,$whence, $callback->($offs)
212	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	224	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
213	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	225	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
214	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	226	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
215	aio_readahead $fh,$offset,$length, $callback->($retval)	227	aio_readahead $fh,$offset,$length, $callback->($retval)
216	aio_stat $fh_or_path, $callback->($status)	228	aio_stat $fh_or_path, $callback->($status)
217	aio_lstat $fh, $callback->($status)	229	aio_lstat $fh, $callback->($status)
218	aio_statvfs $fh_or_path, $callback->($statvfs)	230	aio_statvfs $fh_or_path, $callback->($statvfs)
219	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	231	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
220	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	232	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		233	aio_chmod $fh_or_path, $mode, $callback->($status)
221	aio_truncate $fh_or_path, $offset, $callback->($status)	234	aio_truncate $fh_or_path, $offset, $callback->($status)
222	aio_chmod $fh_or_path, $mode, $callback->($status)	235	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		236	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
223	aio_unlink $pathname, $callback->($status)	237	aio_unlink $pathname, $callback->($status)
224	aio_mknod $path, $mode, $dev, $callback->($status)	238	aio_mknod $pathname, $mode, $dev, $callback->($status)
225	aio_link $srcpath, $dstpath, $callback->($status)	239	aio_link $srcpath, $dstpath, $callback->($status)
226	aio_symlink $srcpath, $dstpath, $callback->($status)	240	aio_symlink $srcpath, $dstpath, $callback->($status)
227	aio_readlink $path, $callback->($link)	241	aio_readlink $pathname, $callback->($link)
228	aio_realpath $path, $callback->($link)	242	aio_realpath $pathname, $callback->($path)
229	aio_rename $srcpath, $dstpath, $callback->($status)	243	aio_rename $srcpath, $dstpath, $callback->($status)
		244	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
230	aio_mkdir $pathname, $mode, $callback->($status)	245	aio_mkdir $pathname, $mode, $callback->($status)
231	aio_rmdir $pathname, $callback->($status)	246	aio_rmdir $pathname, $callback->($status)
232	aio_readdir $pathname, $callback->($entries)	247	aio_readdir $pathname, $callback->($entries)
233	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	248	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
234	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	249	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
235	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	250	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		251	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
236	aio_load $path, $data, $callback->($status)	252	aio_load $pathname, $data, $callback->($status)
237	aio_copy $srcpath, $dstpath, $callback->($status)	253	aio_copy $srcpath, $dstpath, $callback->($status)
238	aio_move $srcpath, $dstpath, $callback->($status)	254	aio_move $srcpath, $dstpath, $callback->($status)
239	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
240	aio_rmtree $path, $callback->($status)	255	aio_rmtree $pathname, $callback->($status)
		256	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		257	aio_ioctl $fh, $request, $buf, $callback->($status)
241	aio_sync $callback->($status)	258	aio_sync $callback->($status)
		259	aio_syncfs $fh, $callback->($status)
242	aio_fsync $fh, $callback->($status)	260	aio_fsync $fh, $callback->($status)
243	aio_fdatasync $fh, $callback->($status)	261	aio_fdatasync $fh, $callback->($status)
244	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	262	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
245	aio_pathsync $path, $callback->($status)	263	aio_pathsync $pathname, $callback->($status)
246	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	264	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
247	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	265	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
248	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	266	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
249	aio_mlockall $flags, $callback->($status)	267	aio_mlockall $flags, $callback->($status)
250	aio_group $callback->(...)	268	aio_group $callback->(...)
251	aio_nop $callback->()	269	aio_nop $callback->()
…		…
265	IO::AIO::idle_timeout $seconds	283	IO::AIO::idle_timeout $seconds
266	IO::AIO::max_outstanding $maxreqs	284	IO::AIO::max_outstanding $maxreqs
267	IO::AIO::nreqs	285	IO::AIO::nreqs
268	IO::AIO::nready	286	IO::AIO::nready
269	IO::AIO::npending	287	IO::AIO::npending
		288	IO::AIO::reinit
		289
		290	$nfd = IO::AIO::get_fdlimit
		291	IO::AIO::min_fdlimit $nfd
270		292
271	IO::AIO::sendfile $ofh, $ifh, $offset, $count	293	IO::AIO::sendfile $ofh, $ifh, $offset, $count
272	IO::AIO::fadvise $fh, $offset, $len, $advice	294	IO::AIO::fadvise $fh, $offset, $len, $advice
		295	IO::AIO::fexecve $fh, $argv, $envp
		296
		297	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		298	IO::AIO::munmap $scalar
		299	IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
273	IO::AIO::madvise $scalar, $offset, $length, $advice	300	IO::AIO::madvise $scalar, $offset, $length, $advice
274	IO::AIO::mprotect $scalar, $offset, $length, $protect	301	IO::AIO::mprotect $scalar, $offset, $length, $protect
275	IO::AIO::munlock $scalar, $offset = 0, $length = undef	302	IO::AIO::munlock $scalar, $offset = 0, $length = undef
276	IO::AIO::munlockall	303	IO::AIO::munlockall
277		304
278	=head2 AIO REQUEST FUNCTIONS	305	# stat extensions
		306	$counter = IO::AIO::st_gen
		307	$seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		308	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		309	$nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		310	$seconds = IO::AIO::st_btimesec
		311	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		312
		313	# very much unportable syscalls
		314	IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
		315	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		316	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		317
		318	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		319	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		320
		321	$fh = IO::AIO::eventfd [$initval, [$flags]]
		322	$fh = IO::AIO::memfd_create $pathname[, $flags]
		323
		324	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		325	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		326	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		327
		328	$fh = IO::AIO::pidfd_open $pid[, $flags]
		329	$status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		330	$fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		331
		332	$retval = IO::AIO::mount $special, $path, $fstype, $flags = 0, $data = undef
		333	$retval = IO::AIO::umount $path, $flags = 0
		334
		335	=head2 API NOTES
279		336
280	All the C<aio_*> calls are more or less thin wrappers around the syscall	337	All the C<aio_*> calls are more or less thin wrappers around the syscall
281	with the same name (sans C<aio_>). The arguments are similar or identical,	338	with the same name (sans C<aio_>). The arguments are similar or identical,
282	and they all accept an additional (and optional) C<$callback> argument	339	and they all accept an additional (and optional) C<$callback> argument
283	which must be a code reference. This code reference will get called with	340	which must be a code reference. This code reference will be called after
284	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	341	the syscall has been executed in an asynchronous fashion. The results
285	perl, which usually delivers "false") as its sole argument after the given	342	of the request will be passed as arguments to the callback (and, if an
286	syscall has been executed asynchronously.	343	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		344	most syscalls return C<-1> on error, unlike perl, which usually delivers
		345	"false").
		346
		347	Some requests (such as C<aio_readdir>) pass the actual results and
		348	communicate failures by passing C<undef>.
287		349
288	All functions expecting a filehandle keep a copy of the filehandle	350	All functions expecting a filehandle keep a copy of the filehandle
289	internally until the request has finished.	351	internally until the request has finished.
290		352
291	All functions return request objects of type L<IO::AIO::REQ> that allow	353	All functions return request objects of type L<IO::AIO::REQ> that allow
292	further manipulation of those requests while they are in-flight.	354	further manipulation of those requests while they are in-flight.
293		355
294	The pathnames you pass to these routines I<must> be absolute and	356	The pathnames you pass to these routines I<should> be absolute. The
295	encoded as octets. The reason for the former is that at the time the	357	reason for this is that at the time the request is being executed, the
296	request is being executed, the current working directory could have	358	current working directory could have changed. Alternatively, you can
297	changed. Alternatively, you can make sure that you never change the	359	make sure that you never change the current working directory anywhere
298	current working directory anywhere in the program and then use relative	360	in the program and then use relative paths. You can also take advantage
299	paths.	361	of IO::AIOs working directory abstraction, that lets you specify paths
		362	relative to some previously-opened "working directory object" - see the
		363	description of the C<IO::AIO::WD> class later in this document.
300		364
301	To encode pathnames as octets, either make sure you either: a) always pass	365	To encode pathnames as octets, either make sure you either: a) always pass
302	in filenames you got from outside (command line, readdir etc.) without	366	in filenames you got from outside (command line, readdir etc.) without
303	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	367	tinkering, b) are in your native filesystem encoding, c) use the Encode
304	your pathnames to the locale (or other) encoding in effect in the user	368	module and encode your pathnames to the locale (or other) encoding in
305	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	369	effect in the user environment, d) use Glib::filename_from_unicode on
306	use something else to ensure your scalar has the correct contents.	370	unicode filenames or e) use something else to ensure your scalar has the
		371	correct contents.
307		372
308	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	373	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
309	handles correctly whether it is set or not.	374	handles correctly whether it is set or not.
		375
		376	=head2 AIO REQUEST FUNCTIONS
310		377
311	=over 4	378	=over 4
312		379
313	=item $prev_pri = aioreq_pri [$pri]	380	=item $prev_pri = aioreq_pri [$pri]
314		381
…		…
344		411
345		412
346	=item aio_open $pathname, $flags, $mode, $callback->($fh)	413	=item aio_open $pathname, $flags, $mode, $callback->($fh)
347		414
348	Asynchronously open or create a file and call the callback with a newly	415	Asynchronously open or create a file and call the callback with a newly
349	created filehandle for the file.	416	created filehandle for the file (or C<undef> in case of an error).
350
351	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
352	for an explanation.
353		417
354	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	418	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
355	list. They are the same as used by C<sysopen>.	419	list. They are the same as used by C<sysopen>.
356		420
357	Likewise, C<$mode> specifies the mode of the newly created file, if it	421	Likewise, C<$mode> specifies the mode of the newly created file, if it
…		…
377	following POSIX and non-POSIX constants are available (missing ones on	441	following POSIX and non-POSIX constants are available (missing ones on
378	your system are, as usual, C<0>):	442	your system are, as usual, C<0>):
379		443
380	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,	444	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
381	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,	445	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
382	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.	446	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
383		447
384		448
385	=item aio_close $fh, $callback->($status)	449	=item aio_close $fh, $callback->($status)
386		450
387	Asynchronously close a file and call the callback with the result	451	Asynchronously close a file and call the callback with the result
…		…
397	Or in other words: the file descriptor will be closed, but it will not be	461	Or in other words: the file descriptor will be closed, but it will not be
398	free for reuse until the perl filehandle is closed.	462	free for reuse until the perl filehandle is closed.
399		463
400	=cut	464	=cut
401		465
		466	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		467
		468	Seeks the filehandle to the new C<$offset>, similarly to perl's
		469	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		470	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		471	C<IO::AIO::SEEK_END>).
		472
		473	The resulting absolute offset will be passed to the callback, or C<-1> in
		474	case of an error.
		475
		476	In theory, the C<$whence> constants could be different than the
		477	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		478	so don't panic.
		479
		480	As a GNU/Linux (and maybe Solaris) extension, also the constants
		481	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		482	could be found. No guarantees about suitability for use in C<aio_seek> or
		483	Perl's C<sysseek> can be made though, although I would naively assume they
		484	"just work".
		485
402	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	486	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
403		487
404	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	488	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
405		489
406	Reads or writes C<$length> bytes from or to the specified C<$fh> and	490	Reads or writes C<$length> bytes from or to the specified C<$fh> and
407	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	491	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
408	and calls the callback without the actual number of bytes read (or -1 on	492	calls the callback with the actual number of bytes transferred (or -1 on
409	error, just like the syscall).	493	error, just like the syscall).
410		494
411	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	495	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
412	offset plus the actual number of bytes read.	496	offset plus the actual number of bytes read.
413		497
…		…
471	As native sendfile syscalls (as practically any non-POSIX interface hacked	555	As native sendfile syscalls (as practically any non-POSIX interface hacked
472	together in a hurry to improve benchmark numbers) tend to be rather buggy	556	together in a hurry to improve benchmark numbers) tend to be rather buggy
473	on many systems, this implementation tries to work around some known bugs	557	on many systems, this implementation tries to work around some known bugs
474	in Linux and FreeBSD kernels (probably others, too), but that might fail,	558	in Linux and FreeBSD kernels (probably others, too), but that might fail,
475	so you really really should check the return value of C<aio_sendfile> -	559	so you really really should check the return value of C<aio_sendfile> -
476	fewre bytes than expected might have been transferred.	560	fewer bytes than expected might have been transferred.
477		561
478		562
479	=item aio_readahead $fh,$offset,$length, $callback->($retval)	563	=item aio_readahead $fh,$offset,$length, $callback->($retval)
480		564
481	C<aio_readahead> populates the page cache with data from a file so that	565	C<aio_readahead> populates the page cache with data from a file so that
…		…
485	whole pages, so that offset is effectively rounded down to a page boundary	569	whole pages, so that offset is effectively rounded down to a page boundary
486	and bytes are read up to the next page boundary greater than or equal to	570	and bytes are read up to the next page boundary greater than or equal to
487	(off-set+length). C<aio_readahead> does not read beyond the end of the	571	(off-set+length). C<aio_readahead> does not read beyond the end of the
488	file. The current file offset of the file is left unchanged.	572	file. The current file offset of the file is left unchanged.
489		573
490	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	574	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
491	emulated by simply reading the data, which would have a similar effect.	575	be emulated by simply reading the data, which would have a similar effect.
492		576
493		577
494	=item aio_stat $fh_or_path, $callback->($status)	578	=item aio_stat $fh_or_path, $callback->($status)
495		579
496	=item aio_lstat $fh, $callback->($status)	580	=item aio_lstat $fh, $callback->($status)
497		581
498	Works like perl's C<stat> or C<lstat> in void context. The callback will	582	Works almost exactly like perl's C<stat> or C<lstat> in void context. The
499	be called after the stat and the results will be available using C<stat _>	583	callback will be called after the stat and the results will be available
500	or C<-s _> etc...	584	using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
501		585	and C<-T>).
502	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
503	for an explanation.
504		586
505	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	587	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
506	error when stat'ing a large file, the results will be silently truncated	588	error when stat'ing a large file, the results will be silently truncated
507	unless perl itself is compiled with large file support.	589	unless perl itself is compiled with large file support.
508		590
…		…
512	behaviour).	594	behaviour).
513		595
514	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,	596	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
515	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,	597	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
516	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.	598	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		599
		600	To access higher resolution stat timestamps, see L<SUBSECOND STAT TIME
		601	ACCESS>.
517		602
518	Example: Print the length of F</etc/passwd>:	603	Example: Print the length of F</etc/passwd>:
519		604
520	aio_stat "/etc/passwd", sub {	605	aio_stat "/etc/passwd", sub {
521	$_[0] and die "stat failed: $!";	606	$_[0] and die "stat failed: $!";
…		…
565	namemax => 255,	650	namemax => 255,
566	frsize => 1024,	651	frsize => 1024,
567	fsid => 1810	652	fsid => 1810
568	}	653	}
569		654
570
571	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	655	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
572		656
573	Works like perl's C<utime> function (including the special case of $atime	657	Works like perl's C<utime> function (including the special case of $atime
574	and $mtime being undef). Fractional times are supported if the underlying	658	and $mtime being undef). Fractional times are supported if the underlying
575	syscalls support them.	659	syscalls support them.
576		660
577	When called with a pathname, uses utimes(2) if available, otherwise	661	When called with a pathname, uses utimensat(2) or utimes(2) if available,
578	utime(2). If called on a file descriptor, uses futimes(2) if available,	662	otherwise utime(2). If called on a file descriptor, uses futimens(2)
579	otherwise returns ENOSYS, so this is not portable.	663	or futimes(2) if available, otherwise returns ENOSYS, so this is not
		664	portable.
580		665
581	Examples:	666	Examples:
582		667
583	# set atime and mtime to current time (basically touch(1)):	668	# set atime and mtime to current time (basically touch(1)):
584	aio_utime "path", undef, undef;	669	aio_utime "path", undef, undef;
…		…
602	=item aio_truncate $fh_or_path, $offset, $callback->($status)	687	=item aio_truncate $fh_or_path, $offset, $callback->($status)
603		688
604	Works like truncate(2) or ftruncate(2).	689	Works like truncate(2) or ftruncate(2).
605		690
606		691
		692	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		693
		694	Allocates or frees disk space according to the C<$mode> argument. See the
		695	linux C<fallocate> documentation for details.
		696
		697	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		698	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		699	to deallocate a file range.
		700
		701	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		702	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		703	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		704	to unshare shared blocks (see your L<fallocate(2)> manpage).
		705
		706	The file system block size used by C<fallocate> is presumably the
		707	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		708	can dictate other limitations.
		709
		710	If C<fallocate> isn't available or cannot be emulated (currently no
		711	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		712
		713
607	=item aio_chmod $fh_or_path, $mode, $callback->($status)	714	=item aio_chmod $fh_or_path, $mode, $callback->($status)
608		715
609	Works like perl's C<chmod> function.	716	Works like perl's C<chmod> function.
610		717
611		718
…		…
613		720
614	Asynchronously unlink (delete) a file and call the callback with the	721	Asynchronously unlink (delete) a file and call the callback with the
615	result code.	722	result code.
616		723
617		724
618	=item aio_mknod $path, $mode, $dev, $callback->($status)	725	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
619		726
620	[EXPERIMENTAL]	727	[EXPERIMENTAL]
621		728
622	Asynchronously create a device node (or fifo). See mknod(2).	729	Asynchronously create a device node (or fifo). See mknod(2).
623		730
624	The only (POSIX-) portable way of calling this function is:	731	The only (POSIX-) portable way of calling this function is:
625		732
626	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	733	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
627		734
628	See C<aio_stat> for info about some potentially helpful extra constants	735	See C<aio_stat> for info about some potentially helpful extra constants
629	and functions.	736	and functions.
630		737
631	=item aio_link $srcpath, $dstpath, $callback->($status)	738	=item aio_link $srcpath, $dstpath, $callback->($status)
…		…
638		745
639	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	746	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
640	the path C<$dstpath> and call the callback with the result code.	747	the path C<$dstpath> and call the callback with the result code.
641		748
642		749
643	=item aio_readlink $path, $callback->($link)	750	=item aio_readlink $pathname, $callback->($link)
644		751
645	Asynchronously read the symlink specified by C<$path> and pass it to	752	Asynchronously read the symlink specified by C<$path> and pass it to
646	the callback. If an error occurs, nothing or undef gets passed to the	753	the callback. If an error occurs, nothing or undef gets passed to the
647	callback.	754	callback.
648		755
649		756
650	=item aio_realpath $path, $callback->($path)	757	=item aio_realpath $pathname, $callback->($path)
651		758
652	Asynchronously make the path absolute and resolve any symlinks in	759	Asynchronously make the path absolute and resolve any symlinks in
653	C<$path>. The resulting path only consists of directories (Same as	760	C<$path>. The resulting path only consists of directories (same as
654	L<Cwd::realpath>).	761	L<Cwd::realpath>).
655		762
656	This request can be used to get the absolute path of the current working	763	This request can be used to get the absolute path of the current working
657	directory by passing it a path of F<.> (a single dot).	764	directory by passing it a path of F<.> (a single dot).
658		765
659		766
660	=item aio_rename $srcpath, $dstpath, $callback->($status)	767	=item aio_rename $srcpath, $dstpath, $callback->($status)
661		768
662	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	769	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
663	rename(2) and call the callback with the result code.	770	rename(2) and call the callback with the result code.
		771
		772	On systems that support the AIO::WD working directory abstraction
		773	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		774	of failing, C<rename> is called on the absolute path of C<$wd>.
		775
		776
		777	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		778
		779	Basically a version of C<aio_rename> with an additional C<$flags>
		780	argument. Calling this with C<$flags=0> is the same as calling
		781	C<aio_rename>.
		782
		783	Non-zero flags are currently only supported on GNU/Linux systems that
		784	support renameat2. Other systems fail with C<ENOSYS> in this case.
		785
		786	The following constants are available (missing ones are, as usual C<0>),
		787	see renameat2(2) for details:
		788
		789	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		790	and C<IO::AIO::RENAME_WHITEOUT>.
664		791
665		792
666	=item aio_mkdir $pathname, $mode, $callback->($status)	793	=item aio_mkdir $pathname, $mode, $callback->($status)
667		794
668	Asynchronously mkdir (create) a directory and call the callback with	795	Asynchronously mkdir (create) a directory and call the callback with
…		…
673	=item aio_rmdir $pathname, $callback->($status)	800	=item aio_rmdir $pathname, $callback->($status)
674		801
675	Asynchronously rmdir (delete) a directory and call the callback with the	802	Asynchronously rmdir (delete) a directory and call the callback with the
676	result code.	803	result code.
677		804
		805	On systems that support the AIO::WD working directory abstraction
		806	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		807	C<rmdir> is called on the absolute path of C<$wd>.
		808
678		809
679	=item aio_readdir $pathname, $callback->($entries)	810	=item aio_readdir $pathname, $callback->($entries)
680		811
681	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	812	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
682	directory (i.e. opendir + readdir + closedir). The entries will not be	813	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
686	array-ref with the filenames.	817	array-ref with the filenames.
687		818
688		819
689	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	820	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
690		821
691	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	822	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
692	behaviour and output format. In case of an error, C<$entries> will be	823	tune behaviour and output format. In case of an error, C<$entries> will be
693	C<undef>.	824	C<undef>.
694		825
695	The flags are a combination of the following constants, ORed together (the	826	The flags are a combination of the following constants, ORed together (the
696	flags will also be passed to the callback, possibly modified):	827	flags will also be passed to the callback, possibly modified):
697		828
698	=over 4	829	=over 4
699		830
700	=item IO::AIO::READDIR_DENTS	831	=item IO::AIO::READDIR_DENTS
701		832
702	When this flag is off, then the callback gets an arrayref consisting of	833	Normally the callback gets an arrayref consisting of names only (as
703	names only (as with C<aio_readdir>), otherwise it gets an arrayref with	834	with C<aio_readdir>). If this flag is set, then the callback gets an
704	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	835	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
705	entry in more detail.	836	single directory entry in more detail:
706		837
707	C<$name> is the name of the entry.	838	C<$name> is the name of the entry.
708		839
709	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	840	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
710		841
711	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	842	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
712	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	843	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
713	C<IO::AIO::DT_WHT>.	844	C<IO::AIO::DT_WHT>.
714		845
715	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	846	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
716	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	847	to know, you have to run stat yourself. Also, for speed/memory reasons,
717	scalars are read-only: you can not modify them.	848	the C<$type> scalars are read-only: you must not modify them.
718		849
719	C<$inode> is the inode number (which might not be exact on systems with 64	850	C<$inode> is the inode number (which might not be exact on systems with 64
720	bit inode numbers and 32 bit perls). This field has unspecified content on	851	bit inode numbers and 32 bit perls). This field has unspecified content on
721	systems that do not deliver the inode information.	852	systems that do not deliver the inode information.
722		853
…		…
733	short names are tried first.	864	short names are tried first.
734		865
735	=item IO::AIO::READDIR_STAT_ORDER	866	=item IO::AIO::READDIR_STAT_ORDER
736		867
737	When this flag is set, then the names will be returned in an order	868	When this flag is set, then the names will be returned in an order
738	suitable for stat()'ing each one. That is, when you plan to stat()	869	suitable for stat()'ing each one. That is, when you plan to stat() most or
739	all files in the given directory, then the returned order will likely	870	all files in the given directory, then the returned order will likely be
740	be fastest.	871	faster.
741		872
742	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then	873	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
743	the likely dirs come first, resulting in a less optimal stat order.	874	then the likely dirs come first, resulting in a less optimal stat order
		875	for stat'ing all entries, but likely a more optimal order for finding
		876	subdirectories.
744		877
745	=item IO::AIO::READDIR_FOUND_UNKNOWN	878	=item IO::AIO::READDIR_FOUND_UNKNOWN
746		879
747	This flag should not be set when calling C<aio_readdirx>. Instead, it	880	This flag should not be set when calling C<aio_readdirx>. Instead, it
748	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	881	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
749	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	882	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
750	C<$type>'s are known, which can be used to speed up some algorithms.	883	C<$type>'s are known, which can be used to speed up some algorithms.
751		884
752	=back	885	=back
753		886
754		887
		888	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		889
		890	Opens, reads and closes the given file. The data is put into C<$data>,
		891	which is resized as required.
		892
		893	If C<$offset> is negative, then it is counted from the end of the file.
		894
		895	If C<$length> is zero, then the remaining length of the file is
		896	used. Also, in this case, the same limitations to modifying C<$data> apply
		897	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		898	with C<substr>. If the size of the file is known, specifying a non-zero
		899	C<$length> results in a performance advantage.
		900
		901	This request is similar to the older C<aio_load> request, but since it is
		902	a single request, it might be more efficient to use.
		903
		904	Example: load F</etc/passwd> into C<$passwd>.
		905
		906	my $passwd;
		907	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		908	$_[0] >= 0
		909	or die "/etc/passwd: $!\n";
		910
		911	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		912	print $passwd;
		913	};
		914	IO::AIO::flush;
		915
		916
755	=item aio_load $path, $data, $callback->($status)	917	=item aio_load $pathname, $data, $callback->($status)
756		918
757	This is a composite request that tries to fully load the given file into	919	This is a composite request that tries to fully load the given file into
758	memory. Status is the same as with aio_read.	920	memory. Status is the same as with aio_read.
		921
		922	Using C<aio_slurp> might be more efficient, as it is a single request.
759		923
760	=cut	924	=cut
761		925
762	sub aio_load($$;$) {	926	sub aio_load($$;$) {
763	my ($path, undef, $cb) = @_;	927	my ($path, undef, $cb) = @_;
…		…
784		948
785	Try to copy the I<file> (directories not supported as either source or	949	Try to copy the I<file> (directories not supported as either source or
786	destination) from C<$srcpath> to C<$dstpath> and call the callback with	950	destination) from C<$srcpath> to C<$dstpath> and call the callback with
787	a status of C<0> (ok) or C<-1> (error, see C<$!>).	951	a status of C<0> (ok) or C<-1> (error, see C<$!>).
788		952
		953	Existing destination files will be truncated.
		954
789	This is a composite request that creates the destination file with	955	This is a composite request that creates the destination file with
790	mode 0200 and copies the contents of the source file into it using	956	mode 0200 and copies the contents of the source file into it using
791	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	957	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
792	uid/gid, in that order.	958	uid/gid, in that order.
793		959
…		…
809	my @stat = stat $src_fh; # hmm, might block over nfs?	975	my @stat = stat $src_fh; # hmm, might block over nfs?
810		976
811	aioreq_pri $pri;	977	aioreq_pri $pri;
812	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	978	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
813	if (my $dst_fh = $_[0]) {	979	if (my $dst_fh = $_[0]) {
		980
		981	# best-effort preallocate
		982	aioreq_pri $pri;
		983	add $grp aio_allocate $dst_fh, IO::AIO::FALLOC_FL_KEEP_SIZE, 0, $stat[7], sub { };
		984
814	aioreq_pri $pri;	985	aioreq_pri $pri;
815	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	986	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
816	if ($_[0] == $stat[7]) {	987	if ($_[0] == $stat[7]) {
817	$grp->result (0);	988	$grp->result (0);
818	close $src_fh;	989	close $src_fh;
…		…
895	};	1066	};
896		1067
897	$grp	1068	$grp
898	}	1069	}
899		1070
900	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1071	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
901		1072
902	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1073	Scans a directory (similar to C<aio_readdir>) but additionally tries to
903	efficiently separate the entries of directory C<$path> into two sets of	1074	efficiently separate the entries of directory C<$path> into two sets of
904	names, directories you can recurse into (directories), and ones you cannot	1075	names, directories you can recurse into (directories), and ones you cannot
905	recurse into (everything else, including symlinks to directories).	1076	recurse into (everything else, including symlinks to directories).
906		1077
907	C<aio_scandir> is a composite request that creates of many sub requests_	1078	C<aio_scandir> is a composite request that generates many sub requests.
908	C<$maxreq> specifies the maximum number of outstanding aio requests that	1079	C<$maxreq> specifies the maximum number of outstanding aio requests that
909	this function generates. If it is C<< <= 0 >>, then a suitable default	1080	this function generates. If it is C<< <= 0 >>, then a suitable default
910	will be chosen (currently 4).	1081	will be chosen (currently 4).
911		1082
912	On error, the callback is called without arguments, otherwise it receives	1083	On error, the callback is called without arguments, otherwise it receives
…		…
936	Then entries will be sorted into likely directories a non-initial dot	1107	Then entries will be sorted into likely directories a non-initial dot
937	currently) and likely non-directories (see C<aio_readdirx>). Then every	1108	currently) and likely non-directories (see C<aio_readdirx>). Then every
938	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1109	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
939	in order of their inode numbers. If that succeeds, it assumes that the	1110	in order of their inode numbers. If that succeeds, it assumes that the
940	entry is a directory or a symlink to directory (which will be checked	1111	entry is a directory or a symlink to directory (which will be checked
941	seperately). This is often faster than stat'ing the entry itself because	1112	separately). This is often faster than stat'ing the entry itself because
942	filesystems might detect the type of the entry without reading the inode	1113	filesystems might detect the type of the entry without reading the inode
943	data (e.g. ext2fs filetype feature), even on systems that cannot return	1114	data (e.g. ext2fs filetype feature), even on systems that cannot return
944	the filetype information on readdir.	1115	the filetype information on readdir.
945		1116
946	If the known number of directories (link count - 2) has been reached, the	1117	If the known number of directories (link count - 2) has been reached, the
…		…
962		1133
963	my $grp = aio_group $cb;	1134	my $grp = aio_group $cb;
964		1135
965	$maxreq = 4 if $maxreq <= 0;	1136	$maxreq = 4 if $maxreq <= 0;
966		1137
967	# stat once	1138	# get a wd object
968	aioreq_pri $pri;	1139	aioreq_pri $pri;
969	add $grp aio_stat $path, sub {	1140	add $grp aio_wd $path, sub {
		1141	$_[0]
970	return $grp->result () if $_[0];	1142	or return $grp->result ();
971	my $now = time;
972	my $hash1 = join ":", (stat _)[0,1,3,7,9];
973		1143
974	# read the directory entries	1144	my $wd = [shift, "."];
		1145
		1146	# stat once
975	aioreq_pri $pri;	1147	aioreq_pri $pri;
976	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1148	add $grp aio_stat $wd, sub {
977	my $entries = shift
978	or return $grp->result ();	1149	return $grp->result () if $_[0];
		1150	my $now = time;
		1151	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		1152	my $rdxflags = READDIR_DIRS_FIRST;
979		1153
980	# stat the dir another time	1154	if ((stat _)[3] < 2) {
		1155	# at least one non-POSIX filesystem exists
		1156	# that returns useful DT_type values: btrfs,
		1157	# so optimise for this here by requesting dents
		1158	$rdxflags |= READDIR_DENTS;
		1159	}
		1160
		1161	# read the directory entries
981	aioreq_pri $pri;	1162	aioreq_pri $pri;
982	add $grp aio_stat $path, sub {	1163	add $grp aio_readdirx $wd, $rdxflags, sub {
983	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1164	my ($entries, $flags) = @_
		1165	or return $grp->result ();
984		1166
		1167	if ($rdxflags & READDIR_DENTS) {
		1168	# if we requested type values, see if we can use them directly.
		1169
		1170	# if there were any DT_UNKNOWN entries then we assume we
		1171	# don't know. alternatively, we could assume that if we get
		1172	# one DT_DIR, then all directories are indeed marked with
		1173	# DT_DIR, but this seems not required for btrfs, and this
		1174	# is basically the "btrfs can't get it's act together" code
		1175	# branch.
		1176	unless ($flags & READDIR_FOUND_UNKNOWN) {
		1177	# now we have valid DT_ information for all entries,
		1178	# so use it as an optimisation without further stat's.
		1179	# they must also all be at the beginning of @$entries
		1180	# by now.
		1181
985	my $ndirs;	1182	my $dirs;
986		1183
987	# take the slow route if anything looks fishy
988	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
989	$ndirs = -1;
990	} else {
991	# if nlink == 2, we are finished
992	# for non-posix-fs's, we rely on nlink < 2
993	$ndirs = (stat _)[3] - 2
994	or return $grp->result ([], $entries);
995	}
996
997	my (@dirs, @nondirs);
998
999	my $statgrp = add $grp aio_group sub {
1000	$grp->result (\@dirs, \@nondirs);
1001	};
1002
1003	limit $statgrp $maxreq;
1004	feed $statgrp sub {
1005	return unless @$entries;
1006	my $entry = shift @$entries;
1007
1008	aioreq_pri $pri;
1009	add $statgrp aio_stat "$path/$entry/.", sub {
1010	if ($_[0] < 0) {	1184	if (@$entries) {
1011	push @nondirs, $entry;	1185	for (0 .. $#$entries) {
1012	} else {	1186	if ($entries->[$_][1] != DT_DIR) {
1013	# need to check for real directory	1187	# splice out directories
1014	aioreq_pri $pri;	1188	$dirs = [splice @$entries, 0, $_];
1015	add $statgrp aio_lstat "$path/$entry", sub {
1016	if (-d _) {
1017	push @dirs, $entry;
1018
1019	unless (--$ndirs) {
1020	push @nondirs, @$entries;
1021	feed $statgrp;
1022	}	1189	last;
1023	} else {
1024	push @nondirs, $entry;
1025	}	1190	}
1026	}	1191	}
		1192
		1193	# if we didn't find any non-dir, then all entries are dirs
		1194	unless ($dirs) {
		1195	($dirs, $entries) = ($entries, []);
		1196	}
		1197	} else {
		1198	# directory is empty, so there are no sbdirs
		1199	$dirs = [];
1027	}	1200	}
		1201
		1202	# either splice'd the directories out or the dir was empty.
		1203	# convert dents to filenames
		1204	$_ = $_->[0] for @$dirs;
		1205	$_ = $_->[0] for @$entries;
		1206
		1207	return $grp->result ($dirs, $entries);
		1208	}
		1209
		1210	# cannot use, so return to our old ways
		1211	# by pretending we only scanned for names.
		1212	$_ = $_->[0] for @$entries;
		1213	}
		1214
		1215	# stat the dir another time
		1216	aioreq_pri $pri;
		1217	add $grp aio_stat $wd, sub {
		1218	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		1219
		1220	my $ndirs;
		1221
		1222	# take the slow route if anything looks fishy
		1223	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
		1224	$ndirs = -1;
		1225	} else {
		1226	# if nlink == 2, we are finished
		1227	# for non-posix-fs's, we rely on nlink < 2
		1228	$ndirs = (stat _)[3] - 2
		1229	or return $grp->result ([], $entries);
		1230	}
		1231
		1232	my (@dirs, @nondirs);
		1233
		1234	my $statgrp = add $grp aio_group sub {
		1235	$grp->result (\@dirs, \@nondirs);
		1236	};
		1237
		1238	limit $statgrp $maxreq;
		1239	feed $statgrp sub {
		1240	return unless @$entries;
		1241	my $entry = shift @$entries;
		1242
		1243	aioreq_pri $pri;
		1244	$wd->[1] = "$entry/.";
		1245	add $statgrp aio_stat $wd, sub {
		1246	if ($_[0] < 0) {
		1247	push @nondirs, $entry;
		1248	} else {
		1249	# need to check for real directory
		1250	aioreq_pri $pri;
		1251	$wd->[1] = $entry;
		1252	add $statgrp aio_lstat $wd, sub {
		1253	if (-d _) {
		1254	push @dirs, $entry;
		1255
		1256	unless (--$ndirs) {
		1257	push @nondirs, @$entries;
		1258	feed $statgrp;
		1259	}
		1260	} else {
		1261	push @nondirs, $entry;
		1262	}
		1263	}
		1264	}
		1265	};
1028	};	1266	};
1029	};	1267	};
1030	};	1268	};
1031	};	1269	};
1032	};	1270	};
1033		1271
1034	$grp	1272	$grp
1035	}	1273	}
1036		1274
1037	=item aio_rmtree $path, $callback->($status)	1275	=item aio_rmtree $pathname, $callback->($status)
1038		1276
1039	Delete a directory tree starting (and including) C<$path>, return the	1277	Delete a directory tree starting (and including) C<$path>, return the
1040	status of the final C<rmdir> only. This is a composite request that	1278	status of the final C<rmdir> only. This is a composite request that
1041	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1279	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1042	everything else.	1280	everything else.
1043		1281
1044	=cut	1282	=cut
1045		1283
…		…
1067	};	1305	};
1068		1306
1069	$grp	1307	$grp
1070	}	1308	}
1071		1309
		1310	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1311
		1312	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1313
		1314	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1315	they execute asynchronously and pass the return value to the callback.
		1316
		1317	Both calls can be used for a lot of things, some of which make more sense
		1318	to run asynchronously in their own thread, while some others make less
		1319	sense. For example, calls that block waiting for external events, such
		1320	as locking, will also lock down an I/O thread while it is waiting, which
		1321	can deadlock the whole I/O system. At the same time, there might be no
		1322	alternative to using a thread to wait.
		1323
		1324	So in general, you should only use these calls for things that do
		1325	(filesystem) I/O, not for things that wait for other events (network,
		1326	other processes), although if you are careful and know what you are doing,
		1327	you still can.
		1328
		1329	The following constants are available and can be used for normal C<ioctl>
		1330	and C<fcntl> as well (missing ones are, as usual C<0>):
		1331
		1332	C<F_DUPFD_CLOEXEC>,
		1333
		1334	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1335
		1336	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1337
		1338	C<F_ADD_SEALS>, C<F_GET_SEALS>, C<F_SEAL_SEAL>, C<F_SEAL_SHRINK>, C<F_SEAL_GROW> and
		1339	C<F_SEAL_WRITE>.
		1340
		1341	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1342	C<FS_IOC_FIEMAP>.
		1343
		1344	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1345	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1346
		1347	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1348	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1349	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1350	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1351	C<FS_FL_USER_MODIFIABLE>.
		1352
		1353	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1354	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1355	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1356	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1357
		1358	C<BLKROSET>, C<BLKROGET>, C<BLKRRPART>, C<BLKGETSIZE>, C<BLKFLSBUF>, C<BLKRASET>,
		1359	C<BLKRAGET>, C<BLKFRASET>, C<BLKFRAGET>, C<BLKSECTSET>, C<BLKSECTGET>, C<BLKSSZGET>,
		1360	C<BLKBSZGET>, C<BLKBSZSET>, C<BLKGETSIZE64>,
		1361
		1362
1072	=item aio_sync $callback->($status)	1363	=item aio_sync $callback->($status)
1073		1364
1074	Asynchronously call sync and call the callback when finished.	1365	Asynchronously call sync and call the callback when finished.
1075		1366
1076	=item aio_fsync $fh, $callback->($status)	1367	=item aio_fsync $fh, $callback->($status)
…		…
1083	Asynchronously call fdatasync on the given filehandle and call the	1374	Asynchronously call fdatasync on the given filehandle and call the
1084	callback with the fdatasync result code.	1375	callback with the fdatasync result code.
1085		1376
1086	If this call isn't available because your OS lacks it or it couldn't be	1377	If this call isn't available because your OS lacks it or it couldn't be
1087	detected, it will be emulated by calling C<fsync> instead.	1378	detected, it will be emulated by calling C<fsync> instead.
		1379
		1380	=item aio_syncfs $fh, $callback->($status)
		1381
		1382	Asynchronously call the syncfs syscall to sync the filesystem associated
		1383	to the given filehandle and call the callback with the syncfs result
		1384	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1385	errno to C<ENOSYS> nevertheless.
1088		1386
1089	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1387	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1090		1388
1091	Sync the data portion of the file specified by C<$offset> and C<$length>	1389	Sync the data portion of the file specified by C<$offset> and C<$length>
1092	to disk (but NOT the metadata), by calling the Linux-specific	1390	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1096	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1394	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1097	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1395	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1098	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1396	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1099	manpage for details.	1397	manpage for details.
1100		1398
1101	=item aio_pathsync $path, $callback->($status)	1399	=item aio_pathsync $pathname, $callback->($status)
1102		1400
1103	This request tries to open, fsync and close the given path. This is a	1401	This request tries to open, fsync and close the given path. This is a
1104	composite request intended to sync directories after directory operations	1402	composite request intended to sync directories after directory operations
1105	(E.g. rename). This might not work on all operating systems or have any	1403	(E.g. rename). This might not work on all operating systems or have any
1106	specific effect, but usually it makes sure that directory changes get	1404	specific effect, but usually it makes sure that directory changes get
…		…
1137	};	1435	};
1138		1436
1139	$grp	1437	$grp
1140	}	1438	}
1141		1439
1142	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1440	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1143		1441
1144	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1442	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1145	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1443	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1146	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1444	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1147	scalar must only be modified in-place while an aio operation is pending on	1445	scalar must only be modified in-place while an aio operation is pending on
…		…
1149		1447
1150	It calls the C<msync> function of your OS, if available, with the memory	1448	It calls the C<msync> function of your OS, if available, with the memory
1151	area starting at C<$offset> in the string and ending C<$length> bytes	1449	area starting at C<$offset> in the string and ending C<$length> bytes
1152	later. If C<$length> is negative, counts from the end, and if C<$length>	1450	later. If C<$length> is negative, counts from the end, and if C<$length>
1153	is C<undef>, then it goes till the end of the string. The flags can be	1451	is C<undef>, then it goes till the end of the string. The flags can be
1154	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1452	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1155	C<IO::AIO::MS_SYNC>.	1453	C<IO::AIO::MS_INVALIDATE>.
1156		1454
1157	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1455	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1158		1456
1159	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1457	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1160	scalars.	1458	scalars.
1161		1459
1162	It touches (reads or writes) all memory pages in the specified	1460	It touches (reads or writes) all memory pages in the specified
1163	range inside the scalar. All caveats and parameters are the same	1461	range inside the scalar. All caveats and parameters are the same
1164	as for C<aio_msync>, above, except for flags, which must be either	1462	as for C<aio_msync>, above, except for flags, which must be either
1165	C<0> (which reads all pages and ensures they are instantiated) or	1463	C<0> (which reads all pages and ensures they are instantiated) or
1166	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1464	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1167	writing an octet from it, which dirties the page).	1465	writing an octet from it, which dirties the page).
1168		1466
1169	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1467	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1170		1468
1171	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1469	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1190	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;	1488	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1191	aio_mlock $data; # mlock in background	1489	aio_mlock $data; # mlock in background
1192		1490
1193	=item aio_mlockall $flags, $callback->($status)	1491	=item aio_mlockall $flags, $callback->($status)
1194		1492
1195	Calls the C<mlockall> function with the given C<$flags> (a combination of	1493	Calls the C<mlockall> function with the given C<$flags> (a
1196	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).	1494	combination of C<IO::AIO::MCL_CURRENT>, C<IO::AIO::MCL_FUTURE> and
		1495	C<IO::AIO::MCL_ONFAULT>).
1197		1496
1198	On systems that do not implement C<mlockall>, this function returns C<-1>	1497	On systems that do not implement C<mlockall>, this function returns C<-1>
1199	and sets errno to C<ENOSYS>.	1498	and sets errno to C<ENOSYS>. Similarly, flag combinations not supported
		1499	by the system result in a return value of C<-1> with errno being set to
		1500	C<EINVAL>.
1200		1501
1201	Note that the corresponding C<munlockall> is synchronous and is	1502	Note that the corresponding C<munlockall> is synchronous and is
1202	documented under L<MISCELLANEOUS FUNCTIONS>.	1503	documented under L<MISCELLANEOUS FUNCTIONS>.
1203		1504
1204	Example: asynchronously lock all current and future pages into memory.	1505	Example: asynchronously lock all current and future pages into memory.
1205		1506
1206	aio_mlockall IO::AIO::MCL_FUTURE;	1507	aio_mlockall IO::AIO::MCL_FUTURE;
		1508
		1509	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1510
		1511	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1512	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1513	the ioctl is not available on your OS, then this request will fail with
		1514	C<ENOSYS>.
		1515
		1516	C<$start> is the starting offset to query extents for, C<$length> is the
		1517	size of the range to query - if it is C<undef>, then the whole file will
		1518	be queried.
		1519
		1520	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1521	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1522	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1523	the data portion.
		1524
		1525	C<$count> is the maximum number of extent records to return. If it is
		1526	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1527	case, if it is C<0>, then the callback receives the number of extents
		1528	instead of the extents themselves (which is unreliable, see below).
		1529
		1530	If an error occurs, the callback receives no arguments. The special
		1531	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1532
		1533	Otherwise, the callback receives an array reference with extent
		1534	structures. Each extent structure is an array reference itself, with the
		1535	following members:
		1536
		1537	[$logical, $physical, $length, $flags]
		1538
		1539	Flags is any combination of the following flag values (typically either C<0>
		1540	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1541
		1542	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1543	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1544	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1545	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1546	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1547	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1548
		1549	At the time of this writing (Linux 3.2), this request is unreliable unless
		1550	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1551	it to return all extents of a range for files with a large number of
		1552	extents. The code (only) works around all these issues if C<$count> is
		1553	C<undef>.
1207		1554
1208	=item aio_group $callback->(...)	1555	=item aio_group $callback->(...)
1209		1556
1210	This is a very special aio request: Instead of doing something, it is a	1557	This is a very special aio request: Instead of doing something, it is a
1211	container for other aio requests, which is useful if you want to bundle	1558	container for other aio requests, which is useful if you want to bundle
…		…
1248	like sleep and file handle readable/writable, the overhead this creates is	1595	like sleep and file handle readable/writable, the overhead this creates is
1249	immense (it blocks a thread for a long time) so do not use this function	1596	immense (it blocks a thread for a long time) so do not use this function
1250	except to put your application under artificial I/O pressure.	1597	except to put your application under artificial I/O pressure.
1251		1598
1252	=back	1599	=back
		1600
		1601
		1602	=head2 IO::AIO::WD - multiple working directories
		1603
		1604	Your process only has one current working directory, which is used by all
		1605	threads. This makes it hard to use relative paths (some other component
		1606	could call C<chdir> at any time, and it is hard to control when the path
		1607	will be used by IO::AIO).
		1608
		1609	One solution for this is to always use absolute paths. This usually works,
		1610	but can be quite slow (the kernel has to walk the whole path on every
		1611	access), and can also be a hassle to implement.
		1612
		1613	Newer POSIX systems have a number of functions (openat, fdopendir,
		1614	futimensat and so on) that make it possible to specify working directories
		1615	per operation.
		1616
		1617	For portability, and because the clowns who "designed", or shall I write,
		1618	perpetrated this new interface were obviously half-drunk, this abstraction
		1619	cannot be perfect, though.
		1620
		1621	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1622	object. This object stores the canonicalised, absolute version of the
		1623	path, and on systems that allow it, also a directory file descriptor.
		1624
		1625	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1626	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1627	object and a pathname instead (or the IO::AIO::WD object alone, which
		1628	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1629	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1630	to that IO::AIO::WD object.
		1631
		1632	For example, to get a wd object for F</etc> and then stat F<passwd>
		1633	inside, you would write:
		1634
		1635	aio_wd "/etc", sub {
		1636	my $etcdir = shift;
		1637
		1638	# although $etcdir can be undef on error, there is generally no reason
		1639	# to check for errors here, as aio_stat will fail with ENOENT
		1640	# when $etcdir is undef.
		1641
		1642	aio_stat [$etcdir, "passwd"], sub {
		1643	# yay
		1644	};
		1645	};
		1646
		1647	The fact that C<aio_wd> is a request and not a normal function shows that
		1648	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1649	which is why it is done asynchronously.
		1650
		1651	To stat the directory obtained with C<aio_wd> above, one could write
		1652	either of the following three request calls:
		1653
		1654	aio_lstat "/etc" , sub { ... # pathname as normal string
		1655	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1656	aio_lstat $wd , sub { ... # shorthand for the previous
		1657
		1658	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1659	object and the pathname string, so you could write the following without
		1660	causing any issues due to C<$path> getting reused:
		1661
		1662	my $path = [$wd, undef];
		1663
		1664	for my $name (qw(abc def ghi)) {
		1665	$path->[1] = $name;
		1666	aio_stat $path, sub {
		1667	# ...
		1668	};
		1669	}
		1670
		1671	There are some caveats: when directories get renamed (or deleted), the
		1672	pathname string doesn't change, so will point to the new directory (or
		1673	nowhere at all), while the directory fd, if available on the system,
		1674	will still point to the original directory. Most functions accepting a
		1675	pathname will use the directory fd on newer systems, and the string on
		1676	older systems. Some functions (such as C<aio_realpath>) will always rely on
		1677	the string form of the pathname.
		1678
		1679	So this functionality is mainly useful to get some protection against
		1680	C<chdir>, to easily get an absolute path out of a relative path for future
		1681	reference, and to speed up doing many operations in the same directory
		1682	(e.g. when stat'ing all files in a directory).
		1683
		1684	The following functions implement this working directory abstraction:
		1685
		1686	=over 4
		1687
		1688	=item aio_wd $pathname, $callback->($wd)
		1689
		1690	Asynchonously canonicalise the given pathname and convert it to an
		1691	IO::AIO::WD object representing it. If possible and supported on the
		1692	system, also open a directory fd to speed up pathname resolution relative
		1693	to this working directory.
		1694
		1695	If something goes wrong, then C<undef> is passwd to the callback instead
		1696	of a working directory object and C<$!> is set appropriately. Since
		1697	passing C<undef> as working directory component of a pathname fails the
		1698	request with C<ENOENT>, there is often no need for error checking in the
		1699	C<aio_wd> callback, as future requests using the value will fail in the
		1700	expected way.
		1701
		1702	=item IO::AIO::CWD
		1703
		1704	This is a compile time constant (object) that represents the process
		1705	current working directory.
		1706
		1707	Specifying this object as working directory object for a pathname is as if
		1708	the pathname would be specified directly, without a directory object. For
		1709	example, these calls are functionally identical:
		1710
		1711	aio_stat "somefile", sub { ... };
		1712	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1713
		1714	=back
		1715
		1716	To recover the path associated with an IO::AIO::WD object, you can use
		1717	C<aio_realpath>:
		1718
		1719	aio_realpath $wd, sub {
		1720	warn "path is $_[0]\n";
		1721	};
		1722
		1723	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1724	sometimes, fall back to using an absolue path.
1253		1725
1254	=head2 IO::AIO::REQ CLASS	1726	=head2 IO::AIO::REQ CLASS
1255		1727
1256	All non-aggregate C<aio_*> functions return an object of this class when	1728	All non-aggregate C<aio_*> functions return an object of this class when
1257	called in non-void context.	1729	called in non-void context.
…		…
1375		1847
1376	Sets a feeder/generator on this group: every group can have an attached	1848	Sets a feeder/generator on this group: every group can have an attached
1377	generator that generates requests if idle. The idea behind this is that,	1849	generator that generates requests if idle. The idea behind this is that,
1378	although you could just queue as many requests as you want in a group,	1850	although you could just queue as many requests as you want in a group,
1379	this might starve other requests for a potentially long time. For example,	1851	this might starve other requests for a potentially long time. For example,
1380	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1852	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1381	delaying any later requests for a long time.	1853	requests, delaying any later requests for a long time.
1382		1854
1383	To avoid this, and allow incremental generation of requests, you can	1855	To avoid this, and allow incremental generation of requests, you can
1384	instead a group and set a feeder on it that generates those requests. The	1856	instead a group and set a feeder on it that generates those requests. The
1385	feed callback will be called whenever there are few enough (see C<limit>,	1857	feed callback will be called whenever there are few enough (see C<limit>,
1386	below) requests active in the group itself and is expected to queue more	1858	below) requests active in the group itself and is expected to queue more
…		…
1418	The default value for the limit is C<0>, but note that setting a feeder	1890	The default value for the limit is C<0>, but note that setting a feeder
1419	automatically bumps it up to C<2>.	1891	automatically bumps it up to C<2>.
1420		1892
1421	=back	1893	=back
1422		1894
		1895
1423	=head2 SUPPORT FUNCTIONS	1896	=head2 SUPPORT FUNCTIONS
1424		1897
1425	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1898	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1426		1899
1427	=over 4	1900	=over 4
…		…
1435		1908
1436	See C<poll_cb> for an example.	1909	See C<poll_cb> for an example.
1437		1910
1438	=item IO::AIO::poll_cb	1911	=item IO::AIO::poll_cb
1439		1912
1440	Process some outstanding events on the result pipe. You have to call	1913	Process some requests that have reached the result phase (i.e. they have
		1914	been executed but the results are not yet reported). You have to call
		1915	this "regularly" to finish outstanding requests.
		1916
1441	this regularly. Returns C<0> if all events could be processed (or there	1917	Returns C<0> if all events could be processed (or there were no
1442	were no events to process), or C<-1> if it returned earlier for whatever	1918	events to process), or C<-1> if it returned earlier for whatever
1443	reason. Returns immediately when no events are outstanding. The amount of	1919	reason. Returns immediately when no events are outstanding. The amount
1444	events processed depends on the settings of C<IO::AIO::max_poll_req> and	1920	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1445	C<IO::AIO::max_poll_time>.	1921	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1446		1922
1447	If not all requests were processed for whatever reason, the filehandle	1923	If not all requests were processed for whatever reason, the poll file
1448	will still be ready when C<poll_cb> returns, so normally you don't have to	1924	descriptor will still be ready when C<poll_cb> returns, so normally you
1449	do anything special to have it called later.	1925	don't have to do anything special to have it called later.
1450		1926
1451	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1927	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1452	ready, it can be beneficial to call this function from loops which submit	1928	ready, it can be beneficial to call this function from loops which submit
1453	a lot of requests, to make sure the results get processed when they become	1929	a lot of requests, to make sure the results get processed when they become
1454	available and not just when the loop is finished and the event loop takes	1930	available and not just when the loop is finished and the event loop takes
…		…
1463	poll => 'r', async => 1,	1939	poll => 'r', async => 1,
1464	cb => \&IO::AIO::poll_cb);	1940	cb => \&IO::AIO::poll_cb);
1465		1941
1466	=item IO::AIO::poll_wait	1942	=item IO::AIO::poll_wait
1467		1943
1468	If there are any outstanding requests and none of them in the result	1944	Wait until either at least one request is in the result phase or no
1469	phase, wait till the result filehandle becomes ready for reading (simply	1945	requests are outstanding anymore.
1470	does a C<select> on the filehandle. This is useful if you want to	1946
1471	synchronously wait for some requests to finish).	1947	This is useful if you want to synchronously wait for some requests to
		1948	become ready, without actually handling them.
1472		1949
1473	See C<nreqs> for an example.	1950	See C<nreqs> for an example.
1474		1951
1475	=item IO::AIO::poll	1952	=item IO::AIO::poll
1476		1953
…		…
1487		1964
1488	Strictly equivalent to:	1965	Strictly equivalent to:
1489		1966
1490	IO::AIO::poll_wait, IO::AIO::poll_cb	1967	IO::AIO::poll_wait, IO::AIO::poll_cb
1491	while IO::AIO::nreqs;	1968	while IO::AIO::nreqs;
		1969
		1970	This function can be useful at program aborts, to make sure outstanding
		1971	I/O has been done (C<IO::AIO> uses an C<END> block which already calls
		1972	this function on normal exits), or when you are merely using C<IO::AIO>
		1973	for its more advanced functions, rather than for async I/O, e.g.:
		1974
		1975	my ($dirs, $nondirs);
		1976	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1977	IO::AIO::flush;
		1978	# $dirs, $nondirs are now set
1492		1979
1493	=item IO::AIO::max_poll_reqs $nreqs	1980	=item IO::AIO::max_poll_reqs $nreqs
1494		1981
1495	=item IO::AIO::max_poll_time $seconds	1982	=item IO::AIO::max_poll_time $seconds
1496		1983
…		…
1523	poll => 'r', nice => 1,	2010	poll => 'r', nice => 1,
1524	cb => &IO::AIO::poll_cb);	2011	cb => &IO::AIO::poll_cb);
1525		2012
1526	=back	2013	=back
1527		2014
		2015
1528	=head3 CONTROLLING THE NUMBER OF THREADS	2016	=head3 CONTROLLING THE NUMBER OF THREADS
1529		2017
1530	=over	2018	=over
1531		2019
1532	=item IO::AIO::min_parallel $nthreads	2020	=item IO::AIO::min_parallel $nthreads
…		…
1593	longer exceeded.	2081	longer exceeded.
1594		2082
1595	In other words, this setting does not enforce a queue limit, but can be	2083	In other words, this setting does not enforce a queue limit, but can be
1596	used to make poll functions block if the limit is exceeded.	2084	used to make poll functions block if the limit is exceeded.
1597		2085
1598	This is a very bad function to use in interactive programs because it	2086	This is a bad function to use in interactive programs because it blocks,
1599	blocks, and a bad way to reduce concurrency because it is inexact: Better	2087	and a bad way to reduce concurrency because it is inexact. If you need to
		2088	issue many requests without being able to call a poll function on demand,
1600	use an C<aio_group> together with a feed callback.	2089	it is better to use an C<aio_group> together with a feed callback.
1601		2090
1602	It's main use is in scripts without an event loop - when you want to stat	2091	Its main use is in scripts without an event loop - when you want to stat a
1603	a lot of files, you can write somehting like this:	2092	lot of files, you can write something like this:
1604		2093
1605	IO::AIO::max_outstanding 32;	2094	IO::AIO::max_outstanding 32;
1606		2095
1607	for my $path (...) {	2096	for my $path (...) {
1608	aio_stat $path , ...;	2097	aio_stat $path , ...;
1609	IO::AIO::poll_cb;	2098	IO::AIO::poll_cb;
1610	}	2099	}
1611		2100
1612	IO::AIO::flush;	2101	IO::AIO::flush;
1613		2102
1614	The call to C<poll_cb> inside the loop will normally return instantly, but	2103	The call to C<poll_cb> inside the loop will normally return instantly,
1615	as soon as more thna C<32> reqeusts are in-flight, it will block until	2104	allowing the loop to progress, but as soon as more than C<32> requests
1616	some requests have been handled. This keeps the loop from pushing a large	2105	are in-flight, it will block until some requests have been handled. This
1617	number of C<aio_stat> requests onto the queue.	2106	keeps the loop from pushing a large number of C<aio_stat> requests onto
		2107	the queue (which, with many paths to stat, can use up a lot of memory).
1618		2108
1619	The default value for C<max_outstanding> is very large, so there is no	2109	The default value for C<max_outstanding> is very large, so there is no
1620	practical limit on the number of outstanding requests.	2110	practical limit on the number of outstanding requests.
1621		2111
1622	=back	2112	=back
1623		2113
		2114
1624	=head3 STATISTICAL INFORMATION	2115	=head3 STATISTICAL INFORMATION
1625		2116
1626	=over	2117	=over
1627		2118
1628	=item IO::AIO::nreqs	2119	=item IO::AIO::nreqs
…		…
1645	Returns the number of requests currently in the pending state (executed,	2136	Returns the number of requests currently in the pending state (executed,
1646	but not yet processed by poll_cb).	2137	but not yet processed by poll_cb).
1647		2138
1648	=back	2139	=back
1649		2140
		2141
		2142	=head3 SUBSECOND STAT TIME ACCESS
		2143
		2144	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2145	generally find access/modification and change times with subsecond time
		2146	accuracy of the system supports it, but perl's built-in functions only
		2147	return the integer part.
		2148
		2149	The following functions return the timestamps of the most recent
		2150	stat with subsecond precision on most systems and work both after
		2151	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2152	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2153	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2154
		2155	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2156	full resolution without rounding and work with standard perl C<stat>,
		2157	alleviating the need to call the special C<Time::HiRes> functions, which
		2158	do not act like their perl counterparts.
		2159
		2160	On operating systems or file systems where subsecond time resolution is
		2161	not supported or could not be detected, a fractional part of C<0> is
		2162	returned, so it is always safe to call these functions.
		2163
		2164	=over 4
		2165
		2166	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		2167
		2168	Return the access, modication, change or birth time, respectively,
		2169	including fractional part. Due to the limited precision of floating point,
		2170	the accuracy on most platforms is only a bit better than milliseconds
		2171	for times around now - see the I<nsec> function family, below, for full
		2172	accuracy.
		2173
		2174	File birth time is only available when the OS and perl support it (on
		2175	FreeBSD and NetBSD at the time of this writing, although support is
		2176	adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
		2177	it). On systems where it isn't available, C<0> is currently returned, but
		2178	this might change to C<undef> in a future version.
		2179
		2180	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		2181
		2182	Returns access, modification, change and birth time all in one go, and
		2183	maybe more times in the future version.
		2184
		2185	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		2186
		2187	Return the fractional access, modifcation, change or birth time, in nanoseconds,
		2188	as an integer in the range C<0> to C<999999999>.
		2189
		2190	Note that no accessors are provided for access, modification and
		2191	change times - you need to get those from C<stat _> if required (C<int
		2192	IO::AIO::st_atime> and so on will I<not> generally give you the correct
		2193	value).
		2194
		2195	=item $seconds = IO::AIO::st_btimesec
		2196
		2197	The (integral) seconds part of the file birth time, if available.
		2198
		2199	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		2200
		2201	Like the functions above, but returns all four times in one go (and maybe
		2202	more in future versions).
		2203
		2204	=item $counter = IO::AIO::st_gen
		2205
		2206	Returns the generation counter (in practice this is just a random number)
		2207	of the file. This is only available on platforms which have this member in
		2208	their C<struct stat> (most BSDs at the time of this writing) and generally
		2209	only to the root usert. If unsupported, C<0> is returned, but this might
		2210	change to C<undef> in a future version.
		2211
		2212	=back
		2213
		2214	Example: print the high resolution modification time of F</etc>, using
		2215	C<stat>, and C<IO::AIO::aio_stat>.
		2216
		2217	if (stat "/etc") {
		2218	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2219	}
		2220
		2221	IO::AIO::aio_stat "/etc", sub {
		2222	$_[0]
		2223	and return;
		2224
		2225	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2226	};
		2227
		2228	IO::AIO::flush;
		2229
		2230	Output of the awbove on my system, showing reduced and full accuracy:
		2231
		2232	stat(/etc) mtime: 1534043702.020808
		2233	aio_stat(/etc) mtime: 1534043702.020807792
		2234
		2235
1650	=head3 MISCELLANEOUS FUNCTIONS	2236	=head3 MISCELLANEOUS FUNCTIONS
1651		2237
1652	IO::AIO implements some functions that might be useful, but are not	2238	IO::AIO implements some functions that are useful when you want to use
1653	asynchronous.	2239	some "Advanced I/O" function not available to in Perl, without going the
		2240	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2241	counterpart.
1654		2242
1655	=over 4	2243	=over 4
		2244
		2245	=item $retval = IO::AIO::fexecve $fh, $argv, $envp
		2246
		2247	A more-or-less direct equivalent to the POSIX C<fexecve> functions, which
		2248	allows you to specify the program to be executed via a file descriptor (or
		2249	handle). Returns C<-1> and sets errno to C<ENOSYS> if not available.
		2250
		2251	=item $retval = IO::AIO::mount $special, $path, $fstype, $flags = 0, $data = undef
		2252
		2253	Calls the GNU/Linux mount syscall with the given arguments. All except
		2254	C<$flags> are strings, and if C<$data> is C<undef>, a C<NULL> will be
		2255	passed.
		2256
		2257	The following values for C<$flags> are available:
		2258
		2259	C<IO::AIO::MS_RDONLY>, C<IO::AIO::MS_NOSUID>, C<IO::AIO::MS_NODEV>, C<IO::AIO::MS_NOEXEC>, C<IO::AIO::MS_SYNCHRONOUS>,
		2260	C<IO::AIO::MS_REMOUNT>, C<IO::AIO::MS_MANDLOCK>, C<IO::AIO::MS_DIRSYNC>, C<IO::AIO::MS_NOATIME>,
		2261	C<IO::AIO::MS_NODIRATIME>, C<IO::AIO::MS_BIND>, C<IO::AIO::MS_MOVE>, C<IO::AIO::MS_REC>, C<IO::AIO::MS_SILENT>,
		2262	C<IO::AIO::MS_POSIXACL>, C<IO::AIO::MS_UNBINDABLE>, C<IO::AIO::MS_PRIVATE>, C<IO::AIO::MS_SLAVE>, C<IO::AIO::MS_SHARED>,
		2263	C<IO::AIO::MS_RELATIME>, C<IO::AIO::MS_KERNMOUNT>, C<IO::AIO::MS_I_VERSION>, C<IO::AIO::MS_STRICTATIME>,
		2264	C<IO::AIO::MS_LAZYTIME>, C<IO::AIO::MS_ACTIVE>, C<IO::AIO::MS_NOUSER>, C<IO::AIO::MS_RMT_MASK>, C<IO::AIO::MS_MGC_VAL> and
		2265	C<IO::AIO::MS_MGC_MSK>.
		2266
		2267	=item $retval = IO::AIO::umount $path, $flags = 0
		2268
		2269	Invokes the GNU/Linux C<umount> or C<umount2> syscalls. Always calls
		2270	C<umount> if C<$flags> is C<0>, otherwqise always tries to call
		2271	C<umount2>.
		2272
		2273	The following C<$flags> are available:
		2274
		2275	C<IO::AIO::MNT_FORCE>, C<IO::AIO::MNT_DETACH>, C<IO::AIO::MNT_EXPIRE> and C<IO::AIO::UMOUNT_NOFOLLOW>.
		2276
		2277	=item $numfd = IO::AIO::get_fdlimit
		2278
		2279	Tries to find the current file descriptor limit and returns it, or
		2280	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2281	the highest valid file descriptor number.
		2282
		2283	=item IO::AIO::min_fdlimit [$numfd]
		2284
		2285	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2286	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2287	is missing, it will try to set a very high limit, although this is not
		2288	recommended when you know the actual minimum that you require.
		2289
		2290	If the limit cannot be raised enough, the function makes a best-effort
		2291	attempt to increase the limit as much as possible, using various
		2292	tricks, while still failing. You can query the resulting limit using
		2293	C<IO::AIO::get_fdlimit>.
		2294
		2295	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2296	true.
1656		2297
1657	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2298	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1658		2299
1659	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2300	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1660	but is blocking (this makes most sense if you know the input data is	2301	but is blocking (this makes most sense if you know the input data is
…		…
1665		2306
1666	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2307	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1667		2308
1668	Simply calls the C<posix_fadvise> function (see its	2309	Simply calls the C<posix_fadvise> function (see its
1669	manpage for details). The following advice constants are	2310	manpage for details). The following advice constants are
1670	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2311	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1671	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2312	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1672	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2313	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1673		2314
1674	On systems that do not implement C<posix_fadvise>, this function returns	2315	On systems that do not implement C<posix_fadvise>, this function returns
1675	ENOSYS, otherwise the return value of C<posix_fadvise>.	2316	ENOSYS, otherwise the return value of C<posix_fadvise>.
1676		2317
1677	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2318	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1678		2319
1679	Simply calls the C<posix_madvise> function (see its	2320	Simply calls the C<posix_madvise> function (see its
1680	manpage for details). The following advice constants are	2321	manpage for details). The following advice constants are
1681	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2322	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1682	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2323	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2324	C<IO::AIO::MADV_DONTNEED>.
		2325
		2326	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2327	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2328	will be reduced to fit into the C<$scalar>.
1683		2329
1684	On systems that do not implement C<posix_madvise>, this function returns	2330	On systems that do not implement C<posix_madvise>, this function returns
1685	ENOSYS, otherwise the return value of C<posix_madvise>.	2331	ENOSYS, otherwise the return value of C<posix_madvise>.
1686		2332
1687	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2333	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1688		2334
1689	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2335	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1690	$scalar (see its manpage for details). The following protect	2336	$scalar (see its manpage for details). The following protect
1691	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2337	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1692	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2338	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2339
		2340	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2341	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2342	will be reduced to fit into the C<$scalar>.
1693		2343
1694	On systems that do not implement C<mprotect>, this function returns	2344	On systems that do not implement C<mprotect>, this function returns
1695	ENOSYS, otherwise the return value of C<mprotect>.	2345	ENOSYS, otherwise the return value of C<mprotect>.
1696		2346
1697	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2347	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1698		2348
1699	Memory-maps a file (or anonymous memory range) and attaches it to the	2349	Memory-maps a file (or anonymous memory range) and attaches it to the
1700	given C<$scalar>, which will act like a string scalar.	2350	given C<$scalar>, which will act like a string scalar. Returns true on
		2351	success, and false otherwise.
1701		2352
		2353	The scalar must exist, but its contents do not matter - this means you
		2354	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2355	the scalar first.
		2356
1702	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2357	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1703	change the string length, and most read-only operations such as copying it	2358	which don't change the string length, and most read-only operations such
1704	or searching it with regexes and so on.	2359	as copying it or searching it with regexes and so on.
1705		2360
1706	Anything else is unsafe and will, at best, result in memory leaks.	2361	Anything else is unsafe and will, at best, result in memory leaks.
1707		2362
1708	The memory map associated with the C<$scalar> is automatically removed	2363	The memory map associated with the C<$scalar> is automatically removed
1709	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2364	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1710	C<IO::AIO::munmap> functions are called.	2365	or C<IO::AIO::munmap> functions are called on it.
1711		2366
1712	This calls the C<mmap>(2) function internally. See your system's manual	2367	This calls the C<mmap>(2) function internally. See your system's manual
1713	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2368	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1714		2369
1715	The C<$length> must be larger than zero and smaller than the actual	2370	The C<$length> must be larger than zero and smaller than the actual
1716	filesize.	2371	filesize.
1717		2372
1718	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2373	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1719	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2374	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1720		2375
1721	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2376	C<$flags> can be a combination of
1722	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2377	C<IO::AIO::MAP_SHARED> or
1723	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2378	C<IO::AIO::MAP_PRIVATE>,
		2379	or a number of system-specific flags (when not available, the are C<0>):
1724	(which is set to C<MAP_ANON> if your system only provides this	2380	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1725	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2381	C<IO::AIO::MAP_LOCKED>,
1726	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2382	C<IO::AIO::MAP_NORESERVE>,
		2383	C<IO::AIO::MAP_POPULATE>,
1727	C<IO::AIO::MAP_NONBLOCK>	2384	C<IO::AIO::MAP_NONBLOCK>,
		2385	C<IO::AIO::MAP_FIXED>,
		2386	C<IO::AIO::MAP_GROWSDOWN>,
		2387	C<IO::AIO::MAP_32BIT>,
		2388	C<IO::AIO::MAP_HUGETLB>,
		2389	C<IO::AIO::MAP_STACK>,
		2390	C<IO::AIO::MAP_FIXED_NOREPLACE>,
		2391	C<IO::AIO::MAP_SHARED_VALIDATE>,
		2392	C<IO::AIO::MAP_SYNC> or
		2393	C<IO::AIO::MAP_UNINITIALIZED>.
1728		2394
1729	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2395	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1730		2396
1731	C<$offset> is the offset from the start of the file - it generally must be	2397	C<$offset> is the offset from the start of the file - it generally must be
1732	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2398	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1746		2412
1747	=item IO::AIO::munmap $scalar	2413	=item IO::AIO::munmap $scalar
1748		2414
1749	Removes a previous mmap and undefines the C<$scalar>.	2415	Removes a previous mmap and undefines the C<$scalar>.
1750		2416
		2417	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2418
		2419	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2420	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2421	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2422
		2423	Returns true if successful, and false otherwise. If the underlying mmapped
		2424	region has changed address, then the true value has the numerical value
		2425	C<1>, otherwise it has the numerical value C<0>:
		2426
		2427	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2428	or die "mremap: $!";
		2429
		2430	if ($success*1) {
		2431	warn "scalar has chanegd address in memory\n";
		2432	}
		2433
		2434	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2435	implemented, but not supported and might go away in a future version.
		2436
		2437	On systems where this call is not supported or is not emulated, this call
		2438	returns falls and sets C<$!> to C<ENOSYS>.
		2439
		2440	=item IO::AIO::mlockall $flags
		2441
		2442	Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
		2443	but is blocking.
		2444
1751	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef	2445	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1752		2446
1753	Calls the C<munlock> function, undoing the effects of a previous	2447	Calls the C<munlock> function, undoing the effects of a previous
1754	C<aio_mlock> call (see its description for details).	2448	C<aio_mlock> call (see its description for details).
1755		2449
…		…
1757		2451
1758	Calls the C<munlockall> function.	2452	Calls the C<munlockall> function.
1759		2453
1760	On systems that do not implement C<munlockall>, this function returns	2454	On systems that do not implement C<munlockall>, this function returns
1761	ENOSYS, otherwise the return value of C<munlockall>.	2455	ENOSYS, otherwise the return value of C<munlockall>.
		2456
		2457	=item $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		2458
		2459	Uses the GNU/Linux C<accept4(2)> syscall, if available, to accept a socket
		2460	and return the new file handle on success, or sets C<$!> and returns
		2461	C<undef> on error.
		2462
		2463	The remote name of the new socket will be stored in C<$sockaddr>, which
		2464	will be extended to allow for at least C<$sockaddr_maxlen> octets. If the
		2465	socket name does not fit into C<$sockaddr_maxlen> octets, this is signaled
		2466	by returning a longer string in C<$sockaddr>, which might or might not be
		2467	truncated.
		2468
		2469	To accept name-less sockets, use C<undef> for C<$sockaddr> and C<0> for
		2470	C<$sockaddr_maxlen>.
		2471
		2472	The main reasons to use this syscall rather than portable C<accept(2)>
		2473	are that you can specify C<SOCK_NONBLOCK> and/or C<SOCK_CLOEXEC>
		2474	flags and you can accept name-less sockets by specifying C<0> for
		2475	C<$sockaddr_maxlen>, which is sadly not possible with perl's interface to
		2476	C<accept>.
		2477
		2478	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2479
		2480	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2481	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2482	should be the file offset.
		2483
		2484	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2485	silently corrupt the data in this case.
		2486
		2487	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2488	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2489	C<IO::AIO::SPLICE_F_GIFT>.
		2490
		2491	See the C<splice(2)> manpage for details.
		2492
		2493	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2494
		2495	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2496	description for C<IO::AIO::splice> above for details.
		2497
		2498	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2499
		2500	Attempts to query or change the pipe buffer size. Obviously works only
		2501	on pipes, and currently works only on GNU/Linux systems, and fails with
		2502	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2503	size on other systems, drop me a note.
		2504
		2505	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2506
		2507	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2508	C<$flags> is missing or C<0>, then this should be the same as a call to
		2509	perl's built-in C<pipe> function and create a new pipe, and works on
		2510	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2511	(..., 4096, O_BINARY)>.
		2512
		2513	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2514	the given flags (Linux 2.6.27, glibc 2.9).
		2515
		2516	On success, the read and write file handles are returned.
		2517
		2518	On error, nothing will be returned. If the pipe2 syscall is missing and
		2519	C<$flags> is non-zero, fails with C<ENOSYS>.
		2520
		2521	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2522	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2523	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2524
		2525	Example: create a pipe race-free w.r.t. threads and fork:
		2526
		2527	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2528	or die "pipe2: $!\n";
		2529
		2530	=item $fh = IO::AIO::memfd_create $pathname[, $flags]
		2531
		2532	This is a direct interface to the Linux L<memfd_create(2)> system
		2533	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2534	should be C<IO::AIO::MFD_CLOEXEC>.
		2535
		2536	On success, the new memfd filehandle is returned, otherwise returns
		2537	C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
		2538
		2539	Please refer to L<memfd_create(2)> for more info on this call.
		2540
		2541	The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
		2542	C<IO::AIO::MFD_ALLOW_SEALING>, C<IO::AIO::MFD_HUGETLB>,
		2543	C<IO::AIO::MFD_HUGETLB_2MB> and C<IO::AIO::MFD_HUGETLB_1GB>.
		2544
		2545	Example: create a new memfd.
		2546
		2547	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2548	or die "memfd_create: $!\n";
		2549
		2550	=item $fh = IO::AIO::pidfd_open $pid[, $flags]
		2551
		2552	This is an interface to the Linux L<pidfd_open(2)> system call. The
		2553	default for C<$flags> is C<0>.
		2554
		2555	On success, a new pidfd filehandle is returned (that is already set to
		2556	close-on-exec), otherwise returns C<undef>. If the syscall is missing,
		2557	fails with C<ENOSYS>.
		2558
		2559	Example: open pid 6341 as pidfd.
		2560
		2561	my $fh = IO::AIO::pidfd_open 6341
		2562	or die "pidfd_open: $!\n";
		2563
		2564	=item $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		2565
		2566	This is an interface to the Linux L<pidfd_send_signal> system call. The
		2567	default for C<$siginfo> is C<undef> and the default for C<$flags> is C<0>.
		2568
		2569	Returns the system call status. If the syscall is missing, fails with
		2570	C<ENOSYS>.
		2571
		2572	When specified, C<$siginfo> must be a reference to a hash with one or more
		2573	of the following members:
		2574
		2575	=over
		2576
		2577	=item code - the C<si_code> member
		2578
		2579	=item pid - the C<si_pid> member
		2580
		2581	=item uid - the C<si_uid> member
		2582
		2583	=item value_int - the C<si_value.sival_int> member
		2584
		2585	=item value_ptr - the C<si_value.sival_ptr> member, specified as an integer
		2586
		2587	=back
		2588
		2589	Example: send a SIGKILL to the specified process.
		2590
		2591	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
		2592	and die "pidfd_send_signal: $!\n";
		2593
		2594	Example: send a SIGKILL to the specified process with extra data.
		2595
		2596	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
		2597	and die "pidfd_send_signal: $!\n";
		2598
		2599	=item $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		2600
		2601	This is an interface to the Linux L<pidfd_getfd> system call. The default
		2602	for C<$flags> is C<0>.
		2603
		2604	On success, returns a dup'ed copy of the target file descriptor (specified
		2605	as an integer) returned (that is already set to close-on-exec), otherwise
		2606	returns C<undef>. If the syscall is missing, fails with C<ENOSYS>.
		2607
		2608	Example: get a copy of standard error of another process and print soemthing to it.
		2609
		2610	my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
		2611	or die "pidfd_getfd: $!\n";
		2612	print $errfh "stderr\n";
		2613
		2614	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2615
		2616	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2617	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2618
		2619	On success, the new eventfd filehandle is returned, otherwise returns
		2620	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2621
		2622	Please refer to L<eventfd(2)> for more info on this call.
		2623
		2624	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2625	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2626
		2627	Example: create a new eventfd filehandle:
		2628
		2629	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2630	or die "eventfd: $!\n";
		2631
		2632	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2633
		2634	This is a direct interface to the Linux L<timerfd_create(2)> system
		2635	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2636	should be C<IO::AIO::TFD_CLOEXEC>.
		2637
		2638	On success, the new timerfd filehandle is returned, otherwise returns
		2639	C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
		2640
		2641	Please refer to L<timerfd_create(2)> for more info on this call.
		2642
		2643	The following C<$clockid> values are
		2644	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2645	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2646	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2647	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2648
		2649	The following C<$flags> values are available (Linux
		2650	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2651
		2652	Example: create a new timerfd and set it to one-second repeated alarms,
		2653	then wait for two alarms:
		2654
		2655	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2656	or die "timerfd_create: $!\n";
		2657
		2658	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2659	or die "timerfd_settime: $!\n";
		2660
		2661	for (1..2) {
		2662	8 == sysread $fh, my $buf, 8
		2663	or die "timerfd read failure\n";
		2664
		2665	printf "number of expirations (likely 1): %d\n",
		2666	unpack "Q", $buf;
		2667	}
		2668
		2669	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2670
		2671	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2672	call. Please refer to its manpage for more info on this call.
		2673
		2674	The new itimerspec is specified using two (possibly fractional) second
		2675	values, C<$new_interval> and C<$new_value>).
		2676
		2677	On success, the current interval and value are returned (as per
		2678	C<timerfd_gettime>). On failure, the empty list is returned.
		2679
		2680	The following C<$flags> values are
		2681	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2682	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2683
		2684	See C<IO::AIO::timerfd_create> for a full example.
		2685
		2686	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2687
		2688	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2689	call. Please refer to its manpage for more info on this call.
		2690
		2691	On success, returns the current values of interval and value for the given
		2692	timerfd (as potentially fractional second values). On failure, the empty
		2693	list is returned.
1762		2694
1763	=back	2695	=back
1764		2696
1765	=cut	2697	=cut
1766		2698
…		…
1804	=head2 FORK BEHAVIOUR	2736	=head2 FORK BEHAVIOUR
1805		2737
1806	Usage of pthreads in a program changes the semantics of fork	2738	Usage of pthreads in a program changes the semantics of fork
1807	considerably. Specifically, only async-safe functions can be called after	2739	considerably. Specifically, only async-safe functions can be called after
1808	fork. Perl doesn't know about this, so in general, you cannot call fork	2740	fork. Perl doesn't know about this, so in general, you cannot call fork
1809	with defined behaviour in perl. IO::AIO uses pthreads, so this applies,	2741	with defined behaviour in perl if pthreads are involved. IO::AIO uses
1810	but many other extensions and (for inexplicable reasons) perl itself often	2742	pthreads, so this applies, but many other extensions and (for inexplicable
1811	is linked against pthreads, so this limitation applies.	2743	reasons) perl itself often is linked against pthreads, so this limitation
		2744	applies to quite a lot of perls.
1812		2745
1813	Some operating systems have extensions that allow safe use of fork, and	2746	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1814	this module should do "the right thing" on those, and tries on others. At	2747	only works in the process that loaded it. Forking is fully supported, but
1815	the time of this writing (2011) only GNU/Linux supports these extensions	2748	using IO::AIO in the child is not.
1816	to POSIX.	2749
		2750	You might get around by not I<using> IO::AIO before (or after)
		2751	forking. You could also try to call the L<IO::AIO::reinit> function in the
		2752	child:
		2753
		2754	=over 4
		2755
		2756	=item IO::AIO::reinit
		2757
		2758	Abandons all current requests and I/O threads and simply reinitialises all
		2759	data structures. This is not an operation supported by any standards, but
		2760	happens to work on GNU/Linux and some newer BSD systems.
		2761
		2762	The only reasonable use for this function is to call it after forking, if
		2763	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2764	the process will result in undefined behaviour. Calling it at any time
		2765	will also result in any undefined (by POSIX) behaviour.
		2766
		2767	=back
		2768
		2769	=head2 LINUX-SPECIFIC CALLS
		2770
		2771	When a call is documented as "linux-specific" then this means it
		2772	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2773	availability and compatibility of such calls regardless of the platform
		2774	it is compiled on, so platforms such as FreeBSD which often implement
		2775	these calls will work. When in doubt, call them and see if they fail wth
		2776	C<ENOSYS>.
1817		2777
1818	=head2 MEMORY USAGE	2778	=head2 MEMORY USAGE
1819		2779
1820	Per-request usage:	2780	Per-request usage:
1821		2781
…		…
1834	temporary buffers, and each thread requires a stack and other data	2794	temporary buffers, and each thread requires a stack and other data
1835	structures (usually around 16k-128k, depending on the OS).	2795	structures (usually around 16k-128k, depending on the OS).
1836		2796
1837	=head1 KNOWN BUGS	2797	=head1 KNOWN BUGS
1838		2798
1839	Known bugs will be fixed in the next release.	2799	Known bugs will be fixed in the next release :)
		2800
		2801	=head1 KNOWN ISSUES
		2802
		2803	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2804	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2805	non-created hash slots or other scalars I didn't think of. It's best to
		2806	avoid such and either use scalar variables or making sure that the scalar
		2807	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2808
		2809	I am not sure anything can be done about this, so this is considered a
		2810	known issue, rather than a bug.
1840		2811
1841	=head1 SEE ALSO	2812	=head1 SEE ALSO
1842		2813
1843	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2814	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1844	more natural syntax.	2815	more natural syntax and L<IO::FDPass> for file descriptor passing.
1845		2816
1846	=head1 AUTHOR	2817	=head1 AUTHOR
1847		2818
1848	Marc Lehmann <schmorp@schmorp.de>	2819	Marc Lehmann <schmorp@schmorp.de>
1849	http://home.schmorp.de/	2820	http://home.schmorp.de/

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