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Revision 1.203 by root, Thu Jul 7 22:36:18 2011 UTC vs.
Revision 1.312 by root, Tue Jul 27 18:46:06 2021 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 = 4.76;
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);
193		198
194	push @AIO_REQ, qw(aio_busy); # not exported	199	push @AIO_REQ, qw(aio_busy); # not exported
195		200
196	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	201	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
197		202
…		…
201		206
202	=head1 FUNCTIONS	207	=head1 FUNCTIONS
203		208
204	=head2 QUICK OVERVIEW	209	=head2 QUICK OVERVIEW
205		210
206	This section simply lists the prototypes of the most important functions	211	This section simply lists the prototypes most of the functions for
207	for quick reference. See the following sections for function-by-function	212	quick reference. See the following sections for function-by-function
208	documentation.	213	documentation.
209		214
		215	aio_wd $pathname, $callback->($wd)
210	aio_open $pathname, $flags, $mode, $callback->($fh)	216	aio_open $pathname, $flags, $mode, $callback->($fh)
211	aio_close $fh, $callback->($status)	217	aio_close $fh, $callback->($status)
		218	aio_seek $fh,$offset,$whence, $callback->($offs)
212	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	219	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
213	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	220	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
214	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	221	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
215	aio_readahead $fh,$offset,$length, $callback->($retval)	222	aio_readahead $fh,$offset,$length, $callback->($retval)
216	aio_stat $fh_or_path, $callback->($status)	223	aio_stat $fh_or_path, $callback->($status)
217	aio_lstat $fh, $callback->($status)	224	aio_lstat $fh, $callback->($status)
218	aio_statvfs $fh_or_path, $callback->($statvfs)	225	aio_statvfs $fh_or_path, $callback->($statvfs)
219	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	226	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
220	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	227	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		228	aio_chmod $fh_or_path, $mode, $callback->($status)
221	aio_truncate $fh_or_path, $offset, $callback->($status)	229	aio_truncate $fh_or_path, $offset, $callback->($status)
222	aio_chmod $fh_or_path, $mode, $callback->($status)	230	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		231	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
223	aio_unlink $pathname, $callback->($status)	232	aio_unlink $pathname, $callback->($status)
224	aio_mknod $path, $mode, $dev, $callback->($status)	233	aio_mknod $pathname, $mode, $dev, $callback->($status)
225	aio_link $srcpath, $dstpath, $callback->($status)	234	aio_link $srcpath, $dstpath, $callback->($status)
226	aio_symlink $srcpath, $dstpath, $callback->($status)	235	aio_symlink $srcpath, $dstpath, $callback->($status)
227	aio_readlink $path, $callback->($link)	236	aio_readlink $pathname, $callback->($link)
228	aio_realpath $path, $callback->($link)	237	aio_realpath $pathname, $callback->($path)
229	aio_rename $srcpath, $dstpath, $callback->($status)	238	aio_rename $srcpath, $dstpath, $callback->($status)
		239	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
230	aio_mkdir $pathname, $mode, $callback->($status)	240	aio_mkdir $pathname, $mode, $callback->($status)
231	aio_rmdir $pathname, $callback->($status)	241	aio_rmdir $pathname, $callback->($status)
232	aio_readdir $pathname, $callback->($entries)	242	aio_readdir $pathname, $callback->($entries)
233	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	243	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
234	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	244	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
235	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	245	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		246	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
236	aio_load $path, $data, $callback->($status)	247	aio_load $pathname, $data, $callback->($status)
237	aio_copy $srcpath, $dstpath, $callback->($status)	248	aio_copy $srcpath, $dstpath, $callback->($status)
238	aio_move $srcpath, $dstpath, $callback->($status)	249	aio_move $srcpath, $dstpath, $callback->($status)
239	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
240	aio_rmtree $path, $callback->($status)	250	aio_rmtree $pathname, $callback->($status)
		251	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		252	aio_ioctl $fh, $request, $buf, $callback->($status)
241	aio_sync $callback->($status)	253	aio_sync $callback->($status)
		254	aio_syncfs $fh, $callback->($status)
242	aio_fsync $fh, $callback->($status)	255	aio_fsync $fh, $callback->($status)
243	aio_fdatasync $fh, $callback->($status)	256	aio_fdatasync $fh, $callback->($status)
244	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	257	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
245	aio_pathsync $path, $callback->($status)	258	aio_pathsync $pathname, $callback->($status)
246	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	259	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
247	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	260	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
248	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	261	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
249	aio_mlockall $flags, $callback->($status)	262	aio_mlockall $flags, $callback->($status)
250	aio_group $callback->(...)	263	aio_group $callback->(...)
251	aio_nop $callback->()	264	aio_nop $callback->()
…		…
265	IO::AIO::idle_timeout $seconds	278	IO::AIO::idle_timeout $seconds
266	IO::AIO::max_outstanding $maxreqs	279	IO::AIO::max_outstanding $maxreqs
267	IO::AIO::nreqs	280	IO::AIO::nreqs
268	IO::AIO::nready	281	IO::AIO::nready
269	IO::AIO::npending	282	IO::AIO::npending
		283	IO::AIO::reinit
		284
		285	$nfd = IO::AIO::get_fdlimit
		286	IO::AIO::min_fdlimit $nfd
270		287
271	IO::AIO::sendfile $ofh, $ifh, $offset, $count	288	IO::AIO::sendfile $ofh, $ifh, $offset, $count
272	IO::AIO::fadvise $fh, $offset, $len, $advice	289	IO::AIO::fadvise $fh, $offset, $len, $advice
		290
		291	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		292	IO::AIO::munmap $scalar
		293	IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
273	IO::AIO::madvise $scalar, $offset, $length, $advice	294	IO::AIO::madvise $scalar, $offset, $length, $advice
274	IO::AIO::mprotect $scalar, $offset, $length, $protect	295	IO::AIO::mprotect $scalar, $offset, $length, $protect
275	IO::AIO::munlock $scalar, $offset = 0, $length = undef	296	IO::AIO::munlock $scalar, $offset = 0, $length = undef
276	IO::AIO::munlockall	297	IO::AIO::munlockall
277		298
278	=head2 AIO REQUEST FUNCTIONS	299	# stat extensions
		300	$counter = IO::AIO::st_gen
		301	$seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		302	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		303	$nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		304	$seconds = IO::AIO::st_btimesec
		305	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		306
		307	# very much unportable syscalls
		308	IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
		309	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		310	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		311	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		312	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		313	$fh = IO::AIO::memfd_create $pathname[, $flags]
		314	$fh = IO::AIO::eventfd [$initval, [$flags]]
		315	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		316	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		317	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		318
		319	=head2 API NOTES
279		320
280	All the C<aio_*> calls are more or less thin wrappers around the syscall	321	All the C<aio_*> calls are more or less thin wrappers around the syscall
281	with the same name (sans C<aio_>). The arguments are similar or identical,	322	with the same name (sans C<aio_>). The arguments are similar or identical,
282	and they all accept an additional (and optional) C<$callback> argument	323	and they all accept an additional (and optional) C<$callback> argument
283	which must be a code reference. This code reference will get called with	324	which must be a code reference. This code reference will be called after
284	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	325	the syscall has been executed in an asynchronous fashion. The results
285	perl, which usually delivers "false") as its sole argument after the given	326	of the request will be passed as arguments to the callback (and, if an
286	syscall has been executed asynchronously.	327	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		328	most syscalls return C<-1> on error, unlike perl, which usually delivers
		329	"false").
		330
		331	Some requests (such as C<aio_readdir>) pass the actual results and
		332	communicate failures by passing C<undef>.
287		333
288	All functions expecting a filehandle keep a copy of the filehandle	334	All functions expecting a filehandle keep a copy of the filehandle
289	internally until the request has finished.	335	internally until the request has finished.
290		336
291	All functions return request objects of type L<IO::AIO::REQ> that allow	337	All functions return request objects of type L<IO::AIO::REQ> that allow
292	further manipulation of those requests while they are in-flight.	338	further manipulation of those requests while they are in-flight.
293		339
294	The pathnames you pass to these routines I<must> be absolute and	340	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	341	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	342	current working directory could have changed. Alternatively, you can
297	changed. Alternatively, you can make sure that you never change the	343	make sure that you never change the current working directory anywhere
298	current working directory anywhere in the program and then use relative	344	in the program and then use relative paths. You can also take advantage
299	paths.	345	of IO::AIOs working directory abstraction, that lets you specify paths
		346	relative to some previously-opened "working directory object" - see the
		347	description of the C<IO::AIO::WD> class later in this document.
300		348
301	To encode pathnames as octets, either make sure you either: a) always pass	349	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	350	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	351	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	352	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)	353	effect in the user environment, d) use Glib::filename_from_unicode on
306	use something else to ensure your scalar has the correct contents.	354	unicode filenames or e) use something else to ensure your scalar has the
		355	correct contents.
307		356
308	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	357	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
309	handles correctly whether it is set or not.	358	handles correctly whether it is set or not.
		359
		360	=head2 AIO REQUEST FUNCTIONS
310		361
311	=over 4	362	=over 4
312		363
313	=item $prev_pri = aioreq_pri [$pri]	364	=item $prev_pri = aioreq_pri [$pri]
314		365
…		…
344		395
345		396
346	=item aio_open $pathname, $flags, $mode, $callback->($fh)	397	=item aio_open $pathname, $flags, $mode, $callback->($fh)
347		398
348	Asynchronously open or create a file and call the callback with a newly	399	Asynchronously open or create a file and call the callback with a newly
349	created filehandle for the file.	400	created filehandle for the file (or C<undef> in case of an error).
350		401
351	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	402	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
352	for an explanation.	403	for an explanation.
353		404
354	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	405	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
377	following POSIX and non-POSIX constants are available (missing ones on	428	following POSIX and non-POSIX constants are available (missing ones on
378	your system are, as usual, C<0>):	429	your system are, as usual, C<0>):
379		430
380	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,	431	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
381	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,	432	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
382	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.	433	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
383		434
384		435
385	=item aio_close $fh, $callback->($status)	436	=item aio_close $fh, $callback->($status)
386		437
387	Asynchronously close a file and call the callback with the result	438	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	448	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.	449	free for reuse until the perl filehandle is closed.
399		450
400	=cut	451	=cut
401		452
		453	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		454
		455	Seeks the filehandle to the new C<$offset>, similarly to perl's
		456	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		457	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		458	C<IO::AIO::SEEK_END>).
		459
		460	The resulting absolute offset will be passed to the callback, or C<-1> in
		461	case of an error.
		462
		463	In theory, the C<$whence> constants could be different than the
		464	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		465	so don't panic.
		466
		467	As a GNU/Linux (and maybe Solaris) extension, also the constants
		468	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		469	could be found. No guarantees about suitability for use in C<aio_seek> or
		470	Perl's C<sysseek> can be made though, although I would naively assume they
		471	"just work".
		472
402	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	473	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
403		474
404	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	475	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
405		476
406	Reads or writes C<$length> bytes from or to the specified C<$fh> and	477	Reads or writes C<$length> bytes from or to the specified C<$fh> and
407	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	478	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
408	and calls the callback without the actual number of bytes read (or -1 on	479	calls the callback with the actual number of bytes transferred (or -1 on
409	error, just like the syscall).	480	error, just like the syscall).
410		481
411	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	482	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
412	offset plus the actual number of bytes read.	483	offset plus the actual number of bytes read.
413		484
…		…
471	As native sendfile syscalls (as practically any non-POSIX interface hacked	542	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	543	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	544	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,	545	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> -	546	so you really really should check the return value of C<aio_sendfile> -
476	fewre bytes than expected might have been transferred.	547	fewer bytes than expected might have been transferred.
477		548
478		549
479	=item aio_readahead $fh,$offset,$length, $callback->($retval)	550	=item aio_readahead $fh,$offset,$length, $callback->($retval)
480		551
481	C<aio_readahead> populates the page cache with data from a file so that	552	C<aio_readahead> populates the page cache with data from a file so that
…		…
485	whole pages, so that offset is effectively rounded down to a page boundary	556	whole pages, so that offset is effectively rounded down to a page boundary
486	and bytes are read up to the next page boundary greater than or equal to	557	and bytes are read up to the next page boundary greater than or equal to
487	(off-set+length). C<aio_readahead> does not read beyond the end of the	558	(off-set+length). C<aio_readahead> does not read beyond the end of the
488	file. The current file offset of the file is left unchanged.	559	file. The current file offset of the file is left unchanged.
489		560
490	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	561	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
491	emulated by simply reading the data, which would have a similar effect.	562	be emulated by simply reading the data, which would have a similar effect.
492		563
493		564
494	=item aio_stat $fh_or_path, $callback->($status)	565	=item aio_stat $fh_or_path, $callback->($status)
495		566
496	=item aio_lstat $fh, $callback->($status)	567	=item aio_lstat $fh, $callback->($status)
497		568
498	Works like perl's C<stat> or C<lstat> in void context. The callback will	569	Works almost exactly like perl's C<stat> or C<lstat> in void context. The
499	be called after the stat and the results will be available using C<stat _>	570	callback will be called after the stat and the results will be available
500	or C<-s _> etc...	571	using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
		572	and C<-T>).
501		573
502	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,	574	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
503	for an explanation.	575	for an explanation.
504		576
505	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	577	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
…		…
512	behaviour).	584	behaviour).
513		585
514	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,	586	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
515	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,	587	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
516	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.	588	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		589
		590	To access higher resolution stat timestamps, see L<SUBSECOND STAT TIME
		591	ACCESS>.
517		592
518	Example: Print the length of F</etc/passwd>:	593	Example: Print the length of F</etc/passwd>:
519		594
520	aio_stat "/etc/passwd", sub {	595	aio_stat "/etc/passwd", sub {
521	$_[0] and die "stat failed: $!";	596	$_[0] and die "stat failed: $!";
…		…
565	namemax => 255,	640	namemax => 255,
566	frsize => 1024,	641	frsize => 1024,
567	fsid => 1810	642	fsid => 1810
568	}	643	}
569		644
570
571	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	645	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
572		646
573	Works like perl's C<utime> function (including the special case of $atime	647	Works like perl's C<utime> function (including the special case of $atime
574	and $mtime being undef). Fractional times are supported if the underlying	648	and $mtime being undef). Fractional times are supported if the underlying
575	syscalls support them.	649	syscalls support them.
576		650
577	When called with a pathname, uses utimes(2) if available, otherwise	651	When called with a pathname, uses utimensat(2) or utimes(2) if available,
578	utime(2). If called on a file descriptor, uses futimes(2) if available,	652	otherwise utime(2). If called on a file descriptor, uses futimens(2)
579	otherwise returns ENOSYS, so this is not portable.	653	or futimes(2) if available, otherwise returns ENOSYS, so this is not
		654	portable.
580		655
581	Examples:	656	Examples:
582		657
583	# set atime and mtime to current time (basically touch(1)):	658	# set atime and mtime to current time (basically touch(1)):
584	aio_utime "path", undef, undef;	659	aio_utime "path", undef, undef;
…		…
602	=item aio_truncate $fh_or_path, $offset, $callback->($status)	677	=item aio_truncate $fh_or_path, $offset, $callback->($status)
603		678
604	Works like truncate(2) or ftruncate(2).	679	Works like truncate(2) or ftruncate(2).
605		680
606		681
		682	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		683
		684	Allocates or frees disk space according to the C<$mode> argument. See the
		685	linux C<fallocate> documentation for details.
		686
		687	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		688	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		689	to deallocate a file range.
		690
		691	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		692	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		693	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		694	to unshare shared blocks (see your L<fallocate(2)> manpage).
		695
		696	The file system block size used by C<fallocate> is presumably the
		697	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		698	can dictate other limitations.
		699
		700	If C<fallocate> isn't available or cannot be emulated (currently no
		701	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		702
		703
607	=item aio_chmod $fh_or_path, $mode, $callback->($status)	704	=item aio_chmod $fh_or_path, $mode, $callback->($status)
608		705
609	Works like perl's C<chmod> function.	706	Works like perl's C<chmod> function.
610		707
611		708
…		…
613		710
614	Asynchronously unlink (delete) a file and call the callback with the	711	Asynchronously unlink (delete) a file and call the callback with the
615	result code.	712	result code.
616		713
617		714
618	=item aio_mknod $path, $mode, $dev, $callback->($status)	715	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
619		716
620	[EXPERIMENTAL]	717	[EXPERIMENTAL]
621		718
622	Asynchronously create a device node (or fifo). See mknod(2).	719	Asynchronously create a device node (or fifo). See mknod(2).
623		720
624	The only (POSIX-) portable way of calling this function is:	721	The only (POSIX-) portable way of calling this function is:
625		722
626	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	723	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
627		724
628	See C<aio_stat> for info about some potentially helpful extra constants	725	See C<aio_stat> for info about some potentially helpful extra constants
629	and functions.	726	and functions.
630		727
631	=item aio_link $srcpath, $dstpath, $callback->($status)	728	=item aio_link $srcpath, $dstpath, $callback->($status)
…		…
638		735
639	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	736	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
640	the path C<$dstpath> and call the callback with the result code.	737	the path C<$dstpath> and call the callback with the result code.
641		738
642		739
643	=item aio_readlink $path, $callback->($link)	740	=item aio_readlink $pathname, $callback->($link)
644		741
645	Asynchronously read the symlink specified by C<$path> and pass it to	742	Asynchronously read the symlink specified by C<$path> and pass it to
646	the callback. If an error occurs, nothing or undef gets passed to the	743	the callback. If an error occurs, nothing or undef gets passed to the
647	callback.	744	callback.
648		745
649		746
650	=item aio_realpath $path, $callback->($path)	747	=item aio_realpath $pathname, $callback->($path)
651		748
652	Asynchronously make the path absolute and resolve any symlinks in	749	Asynchronously make the path absolute and resolve any symlinks in
653	C<$path>. The resulting path only consists of directories (Same as	750	C<$path>. The resulting path only consists of directories (same as
654	L<Cwd::realpath>).	751	L<Cwd::realpath>).
655		752
656	This request can be used to get the absolute path of the current working	753	This request can be used to get the absolute path of the current working
657	directory by passing it a path of F<.> (a single dot).	754	directory by passing it a path of F<.> (a single dot).
658		755
659		756
660	=item aio_rename $srcpath, $dstpath, $callback->($status)	757	=item aio_rename $srcpath, $dstpath, $callback->($status)
661		758
662	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	759	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
663	rename(2) and call the callback with the result code.	760	rename(2) and call the callback with the result code.
		761
		762	On systems that support the AIO::WD working directory abstraction
		763	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		764	of failing, C<rename> is called on the absolute path of C<$wd>.
		765
		766
		767	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		768
		769	Basically a version of C<aio_rename> with an additional C<$flags>
		770	argument. Calling this with C<$flags=0> is the same as calling
		771	C<aio_rename>.
		772
		773	Non-zero flags are currently only supported on GNU/Linux systems that
		774	support renameat2. Other systems fail with C<ENOSYS> in this case.
		775
		776	The following constants are available (missing ones are, as usual C<0>),
		777	see renameat2(2) for details:
		778
		779	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		780	and C<IO::AIO::RENAME_WHITEOUT>.
664		781
665		782
666	=item aio_mkdir $pathname, $mode, $callback->($status)	783	=item aio_mkdir $pathname, $mode, $callback->($status)
667		784
668	Asynchronously mkdir (create) a directory and call the callback with	785	Asynchronously mkdir (create) a directory and call the callback with
…		…
673	=item aio_rmdir $pathname, $callback->($status)	790	=item aio_rmdir $pathname, $callback->($status)
674		791
675	Asynchronously rmdir (delete) a directory and call the callback with the	792	Asynchronously rmdir (delete) a directory and call the callback with the
676	result code.	793	result code.
677		794
		795	On systems that support the AIO::WD working directory abstraction
		796	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		797	C<rmdir> is called on the absolute path of C<$wd>.
		798
678		799
679	=item aio_readdir $pathname, $callback->($entries)	800	=item aio_readdir $pathname, $callback->($entries)
680		801
681	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	802	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
682	directory (i.e. opendir + readdir + closedir). The entries will not be	803	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
686	array-ref with the filenames.	807	array-ref with the filenames.
687		808
688		809
689	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	810	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
690		811
691	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	812	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	813	tune behaviour and output format. In case of an error, C<$entries> will be
693	C<undef>.	814	C<undef>.
694		815
695	The flags are a combination of the following constants, ORed together (the	816	The flags are a combination of the following constants, ORed together (the
696	flags will also be passed to the callback, possibly modified):	817	flags will also be passed to the callback, possibly modified):
697		818
698	=over 4	819	=over 4
699		820
700	=item IO::AIO::READDIR_DENTS	821	=item IO::AIO::READDIR_DENTS
701		822
702	When this flag is off, then the callback gets an arrayref consisting of	823	Normally the callback gets an arrayref consisting of names only (as
703	names only (as with C<aio_readdir>), otherwise it gets an arrayref with	824	with C<aio_readdir>). If this flag is set, then the callback gets an
704	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	825	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
705	entry in more detail.	826	single directory entry in more detail:
706		827
707	C<$name> is the name of the entry.	828	C<$name> is the name of the entry.
708		829
709	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	830	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
710		831
711	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	832	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
712	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	833	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
713	C<IO::AIO::DT_WHT>.	834	C<IO::AIO::DT_WHT>.
714		835
715	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	836	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
716	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	837	to know, you have to run stat yourself. Also, for speed/memory reasons,
717	scalars are read-only: you can not modify them.	838	the C<$type> scalars are read-only: you must not modify them.
718		839
719	C<$inode> is the inode number (which might not be exact on systems with 64	840	C<$inode> is the inode number (which might not be exact on systems with 64
720	bit inode numbers and 32 bit perls). This field has unspecified content on	841	bit inode numbers and 32 bit perls). This field has unspecified content on
721	systems that do not deliver the inode information.	842	systems that do not deliver the inode information.
722		843
…		…
733	short names are tried first.	854	short names are tried first.
734		855
735	=item IO::AIO::READDIR_STAT_ORDER	856	=item IO::AIO::READDIR_STAT_ORDER
736		857
737	When this flag is set, then the names will be returned in an order	858	When this flag is set, then the names will be returned in an order
738	suitable for stat()'ing each one. That is, when you plan to stat()	859	suitable for stat()'ing each one. That is, when you plan to stat() most or
739	all files in the given directory, then the returned order will likely	860	all files in the given directory, then the returned order will likely be
740	be fastest.	861	faster.
741		862
742	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then	863	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
743	the likely dirs come first, resulting in a less optimal stat order.	864	then the likely dirs come first, resulting in a less optimal stat order
		865	for stat'ing all entries, but likely a more optimal order for finding
		866	subdirectories.
744		867
745	=item IO::AIO::READDIR_FOUND_UNKNOWN	868	=item IO::AIO::READDIR_FOUND_UNKNOWN
746		869
747	This flag should not be set when calling C<aio_readdirx>. Instead, it	870	This flag should not be set when calling C<aio_readdirx>. Instead, it
748	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	871	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
749	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	872	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
750	C<$type>'s are known, which can be used to speed up some algorithms.	873	C<$type>'s are known, which can be used to speed up some algorithms.
751		874
752	=back	875	=back
753		876
754		877
		878	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		879
		880	Opens, reads and closes the given file. The data is put into C<$data>,
		881	which is resized as required.
		882
		883	If C<$offset> is negative, then it is counted from the end of the file.
		884
		885	If C<$length> is zero, then the remaining length of the file is
		886	used. Also, in this case, the same limitations to modifying C<$data> apply
		887	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		888	with C<substr>. If the size of the file is known, specifying a non-zero
		889	C<$length> results in a performance advantage.
		890
		891	This request is similar to the older C<aio_load> request, but since it is
		892	a single request, it might be more efficient to use.
		893
		894	Example: load F</etc/passwd> into C<$passwd>.
		895
		896	my $passwd;
		897	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		898	$_[0] >= 0
		899	or die "/etc/passwd: $!\n";
		900
		901	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		902	print $passwd;
		903	};
		904	IO::AIO::flush;
		905
		906
755	=item aio_load $path, $data, $callback->($status)	907	=item aio_load $pathname, $data, $callback->($status)
756		908
757	This is a composite request that tries to fully load the given file into	909	This is a composite request that tries to fully load the given file into
758	memory. Status is the same as with aio_read.	910	memory. Status is the same as with aio_read.
		911
		912	Using C<aio_slurp> might be more efficient, as it is a single request.
759		913
760	=cut	914	=cut
761		915
762	sub aio_load($$;$) {	916	sub aio_load($$;$) {
763	my ($path, undef, $cb) = @_;	917	my ($path, undef, $cb) = @_;
…		…
783	=item aio_copy $srcpath, $dstpath, $callback->($status)	937	=item aio_copy $srcpath, $dstpath, $callback->($status)
784		938
785	Try to copy the I<file> (directories not supported as either source or	939	Try to copy the I<file> (directories not supported as either source or
786	destination) from C<$srcpath> to C<$dstpath> and call the callback with	940	destination) from C<$srcpath> to C<$dstpath> and call the callback with
787	a status of C<0> (ok) or C<-1> (error, see C<$!>).	941	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		942
		943	Existing destination files will be truncated.
788		944
789	This is a composite request that creates the destination file with	945	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	946	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	947	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
792	uid/gid, in that order.	948	uid/gid, in that order.
…		…
895	};	1051	};
896		1052
897	$grp	1053	$grp
898	}	1054	}
899		1055
900	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1056	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
901		1057
902	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1058	Scans a directory (similar to C<aio_readdir>) but additionally tries to
903	efficiently separate the entries of directory C<$path> into two sets of	1059	efficiently separate the entries of directory C<$path> into two sets of
904	names, directories you can recurse into (directories), and ones you cannot	1060	names, directories you can recurse into (directories), and ones you cannot
905	recurse into (everything else, including symlinks to directories).	1061	recurse into (everything else, including symlinks to directories).
906		1062
907	C<aio_scandir> is a composite request that creates of many sub requests_	1063	C<aio_scandir> is a composite request that generates many sub requests.
908	C<$maxreq> specifies the maximum number of outstanding aio requests that	1064	C<$maxreq> specifies the maximum number of outstanding aio requests that
909	this function generates. If it is C<< <= 0 >>, then a suitable default	1065	this function generates. If it is C<< <= 0 >>, then a suitable default
910	will be chosen (currently 4).	1066	will be chosen (currently 4).
911		1067
912	On error, the callback is called without arguments, otherwise it receives	1068	On error, the callback is called without arguments, otherwise it receives
…		…
936	Then entries will be sorted into likely directories a non-initial dot	1092	Then entries will be sorted into likely directories a non-initial dot
937	currently) and likely non-directories (see C<aio_readdirx>). Then every	1093	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,	1094	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	1095	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	1096	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	1097	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	1098	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	1099	data (e.g. ext2fs filetype feature), even on systems that cannot return
944	the filetype information on readdir.	1100	the filetype information on readdir.
945		1101
946	If the known number of directories (link count - 2) has been reached, the	1102	If the known number of directories (link count - 2) has been reached, the
…		…
962		1118
963	my $grp = aio_group $cb;	1119	my $grp = aio_group $cb;
964		1120
965	$maxreq = 4 if $maxreq <= 0;	1121	$maxreq = 4 if $maxreq <= 0;
966		1122
967	# stat once	1123	# get a wd object
968	aioreq_pri $pri;	1124	aioreq_pri $pri;
969	add $grp aio_stat $path, sub {	1125	add $grp aio_wd $path, sub {
		1126	$_[0]
970	return $grp->result () if $_[0];	1127	or return $grp->result ();
971	my $now = time;
972	my $hash1 = join ":", (stat _)[0,1,3,7,9];
973		1128
974	# read the directory entries	1129	my $wd = [shift, "."];
		1130
		1131	# stat once
975	aioreq_pri $pri;	1132	aioreq_pri $pri;
976	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1133	add $grp aio_stat $wd, sub {
977	my $entries = shift
978	or return $grp->result ();	1134	return $grp->result () if $_[0];
		1135	my $now = time;
		1136	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		1137	my $rdxflags = READDIR_DIRS_FIRST;
979		1138
980	# stat the dir another time	1139	if ((stat _)[3] < 2) {
		1140	# at least one non-POSIX filesystem exists
		1141	# that returns useful DT_type values: btrfs,
		1142	# so optimise for this here by requesting dents
		1143	$rdxflags |= READDIR_DENTS;
		1144	}
		1145
		1146	# read the directory entries
981	aioreq_pri $pri;	1147	aioreq_pri $pri;
982	add $grp aio_stat $path, sub {	1148	add $grp aio_readdirx $wd, $rdxflags, sub {
983	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1149	my ($entries, $flags) = @_
		1150	or return $grp->result ();
984		1151
		1152	if ($rdxflags & READDIR_DENTS) {
		1153	# if we requested type values, see if we can use them directly.
		1154
		1155	# if there were any DT_UNKNOWN entries then we assume we
		1156	# don't know. alternatively, we could assume that if we get
		1157	# one DT_DIR, then all directories are indeed marked with
		1158	# DT_DIR, but this seems not required for btrfs, and this
		1159	# is basically the "btrfs can't get it's act together" code
		1160	# branch.
		1161	unless ($flags & READDIR_FOUND_UNKNOWN) {
		1162	# now we have valid DT_ information for all entries,
		1163	# so use it as an optimisation without further stat's.
		1164	# they must also all be at the beginning of @$entries
		1165	# by now.
		1166
985	my $ndirs;	1167	my $dirs;
986		1168
987	# take the slow route if anything looks fishy
988	if ($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) {	1169	if (@$entries) {
1011	push @nondirs, $entry;	1170	for (0 .. $#$entries) {
1012	} else {	1171	if ($entries->[$_][1] != DT_DIR) {
1013	# need to check for real directory	1172	# splice out directories
1014	aioreq_pri $pri;	1173	$dirs = [splice @$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	}	1174	last;
1023	} else {
1024	push @nondirs, $entry;
1025	}	1175	}
1026	}	1176	}
		1177
		1178	# if we didn't find any non-dir, then all entries are dirs
		1179	unless ($dirs) {
		1180	($dirs, $entries) = ($entries, []);
		1181	}
		1182	} else {
		1183	# directory is empty, so there are no sbdirs
		1184	$dirs = [];
1027	}	1185	}
		1186
		1187	# either splice'd the directories out or the dir was empty.
		1188	# convert dents to filenames
		1189	$_ = $_->[0] for @$dirs;
		1190	$_ = $_->[0] for @$entries;
		1191
		1192	return $grp->result ($dirs, $entries);
		1193	}
		1194
		1195	# cannot use, so return to our old ways
		1196	# by pretending we only scanned for names.
		1197	$_ = $_->[0] for @$entries;
		1198	}
		1199
		1200	# stat the dir another time
		1201	aioreq_pri $pri;
		1202	add $grp aio_stat $wd, sub {
		1203	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		1204
		1205	my $ndirs;
		1206
		1207	# take the slow route if anything looks fishy
		1208	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
		1209	$ndirs = -1;
		1210	} else {
		1211	# if nlink == 2, we are finished
		1212	# for non-posix-fs's, we rely on nlink < 2
		1213	$ndirs = (stat _)[3] - 2
		1214	or return $grp->result ([], $entries);
		1215	}
		1216
		1217	my (@dirs, @nondirs);
		1218
		1219	my $statgrp = add $grp aio_group sub {
		1220	$grp->result (\@dirs, \@nondirs);
		1221	};
		1222
		1223	limit $statgrp $maxreq;
		1224	feed $statgrp sub {
		1225	return unless @$entries;
		1226	my $entry = shift @$entries;
		1227
		1228	aioreq_pri $pri;
		1229	$wd->[1] = "$entry/.";
		1230	add $statgrp aio_stat $wd, sub {
		1231	if ($_[0] < 0) {
		1232	push @nondirs, $entry;
		1233	} else {
		1234	# need to check for real directory
		1235	aioreq_pri $pri;
		1236	$wd->[1] = $entry;
		1237	add $statgrp aio_lstat $wd, sub {
		1238	if (-d _) {
		1239	push @dirs, $entry;
		1240
		1241	unless (--$ndirs) {
		1242	push @nondirs, @$entries;
		1243	feed $statgrp;
		1244	}
		1245	} else {
		1246	push @nondirs, $entry;
		1247	}
		1248	}
		1249	}
		1250	};
1028	};	1251	};
1029	};	1252	};
1030	};	1253	};
1031	};	1254	};
1032	};	1255	};
1033		1256
1034	$grp	1257	$grp
1035	}	1258	}
1036		1259
1037	=item aio_rmtree $path, $callback->($status)	1260	=item aio_rmtree $pathname, $callback->($status)
1038		1261
1039	Delete a directory tree starting (and including) C<$path>, return the	1262	Delete a directory tree starting (and including) C<$path>, return the
1040	status of the final C<rmdir> only. This is a composite request that	1263	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	1264	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1042	everything else.	1265	everything else.
1043		1266
1044	=cut	1267	=cut
1045		1268
…		…
1067	};	1290	};
1068		1291
1069	$grp	1292	$grp
1070	}	1293	}
1071		1294
		1295	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1296
		1297	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1298
		1299	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1300	they execute asynchronously and pass the return value to the callback.
		1301
		1302	Both calls can be used for a lot of things, some of which make more sense
		1303	to run asynchronously in their own thread, while some others make less
		1304	sense. For example, calls that block waiting for external events, such
		1305	as locking, will also lock down an I/O thread while it is waiting, which
		1306	can deadlock the whole I/O system. At the same time, there might be no
		1307	alternative to using a thread to wait.
		1308
		1309	So in general, you should only use these calls for things that do
		1310	(filesystem) I/O, not for things that wait for other events (network,
		1311	other processes), although if you are careful and know what you are doing,
		1312	you still can.
		1313
		1314	The following constants are available and can be used for normal C<ioctl>
		1315	and C<fcntl> as well (missing ones are, as usual C<0>):
		1316
		1317	C<F_DUPFD_CLOEXEC>,
		1318
		1319	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1320
		1321	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1322
		1323	C<F_ADD_SEALS>, C<F_GET_SEALS>, C<F_SEAL_SEAL>, C<F_SEAL_SHRINK>, C<F_SEAL_GROW> and
		1324	C<F_SEAL_WRITE>.
		1325
		1326	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1327	C<FS_IOC_FIEMAP>.
		1328
		1329	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1330	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1331
		1332	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1333	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1334	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1335	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1336	C<FS_FL_USER_MODIFIABLE>.
		1337
		1338	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1339	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1340	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1341	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1342
1072	=item aio_sync $callback->($status)	1343	=item aio_sync $callback->($status)
1073		1344
1074	Asynchronously call sync and call the callback when finished.	1345	Asynchronously call sync and call the callback when finished.
1075		1346
1076	=item aio_fsync $fh, $callback->($status)	1347	=item aio_fsync $fh, $callback->($status)
…		…
1083	Asynchronously call fdatasync on the given filehandle and call the	1354	Asynchronously call fdatasync on the given filehandle and call the
1084	callback with the fdatasync result code.	1355	callback with the fdatasync result code.
1085		1356
1086	If this call isn't available because your OS lacks it or it couldn't be	1357	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.	1358	detected, it will be emulated by calling C<fsync> instead.
		1359
		1360	=item aio_syncfs $fh, $callback->($status)
		1361
		1362	Asynchronously call the syncfs syscall to sync the filesystem associated
		1363	to the given filehandle and call the callback with the syncfs result
		1364	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1365	errno to C<ENOSYS> nevertheless.
1088		1366
1089	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1367	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1090		1368
1091	Sync the data portion of the file specified by C<$offset> and C<$length>	1369	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	1370	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1096	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1374	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1097	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1375	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1098	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1376	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1099	manpage for details.	1377	manpage for details.
1100		1378
1101	=item aio_pathsync $path, $callback->($status)	1379	=item aio_pathsync $pathname, $callback->($status)
1102		1380
1103	This request tries to open, fsync and close the given path. This is a	1381	This request tries to open, fsync and close the given path. This is a
1104	composite request intended to sync directories after directory operations	1382	composite request intended to sync directories after directory operations
1105	(E.g. rename). This might not work on all operating systems or have any	1383	(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	1384	specific effect, but usually it makes sure that directory changes get
…		…
1137	};	1415	};
1138		1416
1139	$grp	1417	$grp
1140	}	1418	}
1141		1419
1142	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1420	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1143		1421
1144	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1422	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1145	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1423	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1146	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1424	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1147	scalar must only be modified in-place while an aio operation is pending on	1425	scalar must only be modified in-place while an aio operation is pending on
…		…
1149		1427
1150	It calls the C<msync> function of your OS, if available, with the memory	1428	It calls the C<msync> function of your OS, if available, with the memory
1151	area starting at C<$offset> in the string and ending C<$length> bytes	1429	area starting at C<$offset> in the string and ending C<$length> bytes
1152	later. If C<$length> is negative, counts from the end, and if C<$length>	1430	later. If C<$length> is negative, counts from the end, and if C<$length>
1153	is C<undef>, then it goes till the end of the string. The flags can be	1431	is C<undef>, then it goes till the end of the string. The flags can be
1154	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1432	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1155	C<IO::AIO::MS_SYNC>.	1433	C<IO::AIO::MS_INVALIDATE>.
1156		1434
1157	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1435	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1158		1436
1159	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1437	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1160	scalars.	1438	scalars.
1161		1439
1162	It touches (reads or writes) all memory pages in the specified	1440	It touches (reads or writes) all memory pages in the specified
1163	range inside the scalar. All caveats and parameters are the same	1441	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	1442	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	1443	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	1444	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1167	writing an octet from it, which dirties the page).	1445	writing an octet from it, which dirties the page).
1168		1446
1169	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1447	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1170		1448
1171	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1449	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1190	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;	1468	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1191	aio_mlock $data; # mlock in background	1469	aio_mlock $data; # mlock in background
1192		1470
1193	=item aio_mlockall $flags, $callback->($status)	1471	=item aio_mlockall $flags, $callback->($status)
1194		1472
1195	Calls the C<mlockall> function with the given C<$flags> (a combination of	1473	Calls the C<mlockall> function with the given C<$flags> (a
1196	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).	1474	combination of C<IO::AIO::MCL_CURRENT>, C<IO::AIO::MCL_FUTURE> and
		1475	C<IO::AIO::MCL_ONFAULT>).
1197		1476
1198	On systems that do not implement C<mlockall>, this function returns C<-1>	1477	On systems that do not implement C<mlockall>, this function returns C<-1>
1199	and sets errno to C<ENOSYS>.	1478	and sets errno to C<ENOSYS>. Similarly, flag combinations not supported
		1479	by the system result in a return value of C<-1> with errno being set to
		1480	C<EINVAL>.
1200		1481
1201	Note that the corresponding C<munlockall> is synchronous and is	1482	Note that the corresponding C<munlockall> is synchronous and is
1202	documented under L<MISCELLANEOUS FUNCTIONS>.	1483	documented under L<MISCELLANEOUS FUNCTIONS>.
1203		1484
1204	Example: asynchronously lock all current and future pages into memory.	1485	Example: asynchronously lock all current and future pages into memory.
1205		1486
1206	aio_mlockall IO::AIO::MCL_FUTURE;	1487	aio_mlockall IO::AIO::MCL_FUTURE;
		1488
		1489	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1490
		1491	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1492	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1493	the ioctl is not available on your OS, then this request will fail with
		1494	C<ENOSYS>.
		1495
		1496	C<$start> is the starting offset to query extents for, C<$length> is the
		1497	size of the range to query - if it is C<undef>, then the whole file will
		1498	be queried.
		1499
		1500	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1501	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1502	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1503	the data portion.
		1504
		1505	C<$count> is the maximum number of extent records to return. If it is
		1506	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1507	case, if it is C<0>, then the callback receives the number of extents
		1508	instead of the extents themselves (which is unreliable, see below).
		1509
		1510	If an error occurs, the callback receives no arguments. The special
		1511	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1512
		1513	Otherwise, the callback receives an array reference with extent
		1514	structures. Each extent structure is an array reference itself, with the
		1515	following members:
		1516
		1517	[$logical, $physical, $length, $flags]
		1518
		1519	Flags is any combination of the following flag values (typically either C<0>
		1520	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1521
		1522	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1523	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1524	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1525	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1526	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1527	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1528
		1529	At the time of this writing (Linux 3.2), this request is unreliable unless
		1530	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1531	it to return all extents of a range for files with a large number of
		1532	extents. The code (only) works around all these issues if C<$count> is
		1533	C<undef>.
1207		1534
1208	=item aio_group $callback->(...)	1535	=item aio_group $callback->(...)
1209		1536
1210	This is a very special aio request: Instead of doing something, it is a	1537	This is a very special aio request: Instead of doing something, it is a
1211	container for other aio requests, which is useful if you want to bundle	1538	container for other aio requests, which is useful if you want to bundle
…		…
1248	like sleep and file handle readable/writable, the overhead this creates is	1575	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	1576	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.	1577	except to put your application under artificial I/O pressure.
1251		1578
1252	=back	1579	=back
		1580
		1581
		1582	=head2 IO::AIO::WD - multiple working directories
		1583
		1584	Your process only has one current working directory, which is used by all
		1585	threads. This makes it hard to use relative paths (some other component
		1586	could call C<chdir> at any time, and it is hard to control when the path
		1587	will be used by IO::AIO).
		1588
		1589	One solution for this is to always use absolute paths. This usually works,
		1590	but can be quite slow (the kernel has to walk the whole path on every
		1591	access), and can also be a hassle to implement.
		1592
		1593	Newer POSIX systems have a number of functions (openat, fdopendir,
		1594	futimensat and so on) that make it possible to specify working directories
		1595	per operation.
		1596
		1597	For portability, and because the clowns who "designed", or shall I write,
		1598	perpetrated this new interface were obviously half-drunk, this abstraction
		1599	cannot be perfect, though.
		1600
		1601	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1602	object. This object stores the canonicalised, absolute version of the
		1603	path, and on systems that allow it, also a directory file descriptor.
		1604
		1605	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1606	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1607	object and a pathname instead (or the IO::AIO::WD object alone, which
		1608	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1609	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1610	to that IO::AIO::WD object.
		1611
		1612	For example, to get a wd object for F</etc> and then stat F<passwd>
		1613	inside, you would write:
		1614
		1615	aio_wd "/etc", sub {
		1616	my $etcdir = shift;
		1617
		1618	# although $etcdir can be undef on error, there is generally no reason
		1619	# to check for errors here, as aio_stat will fail with ENOENT
		1620	# when $etcdir is undef.
		1621
		1622	aio_stat [$etcdir, "passwd"], sub {
		1623	# yay
		1624	};
		1625	};
		1626
		1627	The fact that C<aio_wd> is a request and not a normal function shows that
		1628	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1629	which is why it is done asynchronously.
		1630
		1631	To stat the directory obtained with C<aio_wd> above, one could write
		1632	either of the following three request calls:
		1633
		1634	aio_lstat "/etc" , sub { ... # pathname as normal string
		1635	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1636	aio_lstat $wd , sub { ... # shorthand for the previous
		1637
		1638	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1639	object and the pathname string, so you could write the following without
		1640	causing any issues due to C<$path> getting reused:
		1641
		1642	my $path = [$wd, undef];
		1643
		1644	for my $name (qw(abc def ghi)) {
		1645	$path->[1] = $name;
		1646	aio_stat $path, sub {
		1647	# ...
		1648	};
		1649	}
		1650
		1651	There are some caveats: when directories get renamed (or deleted), the
		1652	pathname string doesn't change, so will point to the new directory (or
		1653	nowhere at all), while the directory fd, if available on the system,
		1654	will still point to the original directory. Most functions accepting a
		1655	pathname will use the directory fd on newer systems, and the string on
		1656	older systems. Some functions (such as C<aio_realpath>) will always rely on
		1657	the string form of the pathname.
		1658
		1659	So this functionality is mainly useful to get some protection against
		1660	C<chdir>, to easily get an absolute path out of a relative path for future
		1661	reference, and to speed up doing many operations in the same directory
		1662	(e.g. when stat'ing all files in a directory).
		1663
		1664	The following functions implement this working directory abstraction:
		1665
		1666	=over 4
		1667
		1668	=item aio_wd $pathname, $callback->($wd)
		1669
		1670	Asynchonously canonicalise the given pathname and convert it to an
		1671	IO::AIO::WD object representing it. If possible and supported on the
		1672	system, also open a directory fd to speed up pathname resolution relative
		1673	to this working directory.
		1674
		1675	If something goes wrong, then C<undef> is passwd to the callback instead
		1676	of a working directory object and C<$!> is set appropriately. Since
		1677	passing C<undef> as working directory component of a pathname fails the
		1678	request with C<ENOENT>, there is often no need for error checking in the
		1679	C<aio_wd> callback, as future requests using the value will fail in the
		1680	expected way.
		1681
		1682	=item IO::AIO::CWD
		1683
		1684	This is a compile time constant (object) that represents the process
		1685	current working directory.
		1686
		1687	Specifying this object as working directory object for a pathname is as if
		1688	the pathname would be specified directly, without a directory object. For
		1689	example, these calls are functionally identical:
		1690
		1691	aio_stat "somefile", sub { ... };
		1692	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1693
		1694	=back
		1695
		1696	To recover the path associated with an IO::AIO::WD object, you can use
		1697	C<aio_realpath>:
		1698
		1699	aio_realpath $wd, sub {
		1700	warn "path is $_[0]\n";
		1701	};
		1702
		1703	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1704	sometimes, fall back to using an absolue path.
1253		1705
1254	=head2 IO::AIO::REQ CLASS	1706	=head2 IO::AIO::REQ CLASS
1255		1707
1256	All non-aggregate C<aio_*> functions return an object of this class when	1708	All non-aggregate C<aio_*> functions return an object of this class when
1257	called in non-void context.	1709	called in non-void context.
…		…
1375		1827
1376	Sets a feeder/generator on this group: every group can have an attached	1828	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,	1829	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,	1830	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,	1831	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,	1832	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1381	delaying any later requests for a long time.	1833	requests, delaying any later requests for a long time.
1382		1834
1383	To avoid this, and allow incremental generation of requests, you can	1835	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	1836	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>,	1837	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	1838	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	1870	The default value for the limit is C<0>, but note that setting a feeder
1419	automatically bumps it up to C<2>.	1871	automatically bumps it up to C<2>.
1420		1872
1421	=back	1873	=back
1422		1874
		1875
1423	=head2 SUPPORT FUNCTIONS	1876	=head2 SUPPORT FUNCTIONS
1424		1877
1425	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1878	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1426		1879
1427	=over 4	1880	=over 4
…		…
1435		1888
1436	See C<poll_cb> for an example.	1889	See C<poll_cb> for an example.
1437		1890
1438	=item IO::AIO::poll_cb	1891	=item IO::AIO::poll_cb
1439		1892
1440	Process some outstanding events on the result pipe. You have to call	1893	Process some requests that have reached the result phase (i.e. they have
		1894	been executed but the results are not yet reported). You have to call
		1895	this "regularly" to finish outstanding requests.
		1896
1441	this regularly. Returns C<0> if all events could be processed (or there	1897	Returns C<0> if all events could be processed (or there were no
1442	were no events to process), or C<-1> if it returned earlier for whatever	1898	events to process), or C<-1> if it returned earlier for whatever
1443	reason. Returns immediately when no events are outstanding. The amount of	1899	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	1900	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1445	C<IO::AIO::max_poll_time>.	1901	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1446		1902
1447	If not all requests were processed for whatever reason, the filehandle	1903	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	1904	descriptor will still be ready when C<poll_cb> returns, so normally you
1449	do anything special to have it called later.	1905	don't have to do anything special to have it called later.
1450		1906
1451	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1907	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1452	ready, it can be beneficial to call this function from loops which submit	1908	ready, it can be beneficial to call this function from loops which submit
1453	a lot of requests, to make sure the results get processed when they become	1909	a lot of requests, to make sure the results get processed when they become
1454	available and not just when the loop is finished and the event loop takes	1910	available and not just when the loop is finished and the event loop takes
…		…
1463	poll => 'r', async => 1,	1919	poll => 'r', async => 1,
1464	cb => \&IO::AIO::poll_cb);	1920	cb => \&IO::AIO::poll_cb);
1465		1921
1466	=item IO::AIO::poll_wait	1922	=item IO::AIO::poll_wait
1467		1923
1468	If there are any outstanding requests and none of them in the result	1924	Wait until either at least one request is in the result phase or no
1469	phase, wait till the result filehandle becomes ready for reading (simply	1925	requests are outstanding anymore.
1470	does a C<select> on the filehandle. This is useful if you want to	1926
1471	synchronously wait for some requests to finish).	1927	This is useful if you want to synchronously wait for some requests to
		1928	become ready, without actually handling them.
1472		1929
1473	See C<nreqs> for an example.	1930	See C<nreqs> for an example.
1474		1931
1475	=item IO::AIO::poll	1932	=item IO::AIO::poll
1476		1933
…		…
1487		1944
1488	Strictly equivalent to:	1945	Strictly equivalent to:
1489		1946
1490	IO::AIO::poll_wait, IO::AIO::poll_cb	1947	IO::AIO::poll_wait, IO::AIO::poll_cb
1491	while IO::AIO::nreqs;	1948	while IO::AIO::nreqs;
		1949
		1950	This function can be useful at program aborts, to make sure outstanding
		1951	I/O has been done (C<IO::AIO> uses an C<END> block which already calls
		1952	this function on normal exits), or when you are merely using C<IO::AIO>
		1953	for its more advanced functions, rather than for async I/O, e.g.:
		1954
		1955	my ($dirs, $nondirs);
		1956	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1957	IO::AIO::flush;
		1958	# $dirs, $nondirs are now set
1492		1959
1493	=item IO::AIO::max_poll_reqs $nreqs	1960	=item IO::AIO::max_poll_reqs $nreqs
1494		1961
1495	=item IO::AIO::max_poll_time $seconds	1962	=item IO::AIO::max_poll_time $seconds
1496		1963
…		…
1523	poll => 'r', nice => 1,	1990	poll => 'r', nice => 1,
1524	cb => &IO::AIO::poll_cb);	1991	cb => &IO::AIO::poll_cb);
1525		1992
1526	=back	1993	=back
1527		1994
		1995
1528	=head3 CONTROLLING THE NUMBER OF THREADS	1996	=head3 CONTROLLING THE NUMBER OF THREADS
1529		1997
1530	=over	1998	=over
1531		1999
1532	=item IO::AIO::min_parallel $nthreads	2000	=item IO::AIO::min_parallel $nthreads
…		…
1597		2065
1598	This is a very bad function to use in interactive programs because it	2066	This is a very bad function to use in interactive programs because it
1599	blocks, and a bad way to reduce concurrency because it is inexact: Better	2067	blocks, and a bad way to reduce concurrency because it is inexact: Better
1600	use an C<aio_group> together with a feed callback.	2068	use an C<aio_group> together with a feed callback.
1601		2069
1602	It's main use is in scripts without an event loop - when you want to stat	2070	Its main use is in scripts without an event loop - when you want to stat
1603	a lot of files, you can write somehting like this:	2071	a lot of files, you can write something like this:
1604		2072
1605	IO::AIO::max_outstanding 32;	2073	IO::AIO::max_outstanding 32;
1606		2074
1607	for my $path (...) {	2075	for my $path (...) {
1608	aio_stat $path , ...;	2076	aio_stat $path , ...;
…		…
1619	The default value for C<max_outstanding> is very large, so there is no	2087	The default value for C<max_outstanding> is very large, so there is no
1620	practical limit on the number of outstanding requests.	2088	practical limit on the number of outstanding requests.
1621		2089
1622	=back	2090	=back
1623		2091
		2092
1624	=head3 STATISTICAL INFORMATION	2093	=head3 STATISTICAL INFORMATION
1625		2094
1626	=over	2095	=over
1627		2096
1628	=item IO::AIO::nreqs	2097	=item IO::AIO::nreqs
…		…
1645	Returns the number of requests currently in the pending state (executed,	2114	Returns the number of requests currently in the pending state (executed,
1646	but not yet processed by poll_cb).	2115	but not yet processed by poll_cb).
1647		2116
1648	=back	2117	=back
1649		2118
		2119
		2120	=head3 SUBSECOND STAT TIME ACCESS
		2121
		2122	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2123	generally find access/modification and change times with subsecond time
		2124	accuracy of the system supports it, but perl's built-in functions only
		2125	return the integer part.
		2126
		2127	The following functions return the timestamps of the most recent
		2128	stat with subsecond precision on most systems and work both after
		2129	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2130	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2131	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2132
		2133	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2134	full resolution without rounding and work with standard perl C<stat>,
		2135	alleviating the need to call the special C<Time::HiRes> functions, which
		2136	do not act like their perl counterparts.
		2137
		2138	On operating systems or file systems where subsecond time resolution is
		2139	not supported or could not be detected, a fractional part of C<0> is
		2140	returned, so it is always safe to call these functions.
		2141
		2142	=over 4
		2143
		2144	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		2145
		2146	Return the access, modication, change or birth time, respectively,
		2147	including fractional part. Due to the limited precision of floating point,
		2148	the accuracy on most platforms is only a bit better than milliseconds
		2149	for times around now - see the I<nsec> function family, below, for full
		2150	accuracy.
		2151
		2152	File birth time is only available when the OS and perl support it (on
		2153	FreeBSD and NetBSD at the time of this writing, although support is
		2154	adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
		2155	it). On systems where it isn't available, C<0> is currently returned, but
		2156	this might change to C<undef> in a future version.
		2157
		2158	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		2159
		2160	Returns access, modification, change and birth time all in one go, and
		2161	maybe more times in the future version.
		2162
		2163	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		2164
		2165	Return the fractional access, modifcation, change or birth time, in nanoseconds,
		2166	as an integer in the range C<0> to C<999999999>.
		2167
		2168	Note that no accessors are provided for access, modification and
		2169	change times - you need to get those from C<stat _> if required (C<int
		2170	IO::AIO::st_atime> and so on will I<not> generally give you the correct
		2171	value).
		2172
		2173	=item $seconds = IO::AIO::st_btimesec
		2174
		2175	The (integral) seconds part of the file birth time, if available.
		2176
		2177	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		2178
		2179	Like the functions above, but returns all four times in one go (and maybe
		2180	more in future versions).
		2181
		2182	=item $counter = IO::AIO::st_gen
		2183
		2184	Returns the generation counter (in practice this is just a random number)
		2185	of the file. This is only available on platforms which have this member in
		2186	their C<struct stat> (most BSDs at the time of this writing) and generally
		2187	only to the root usert. If unsupported, C<0> is returned, but this might
		2188	change to C<undef> in a future version.
		2189
		2190	=back
		2191
		2192	Example: print the high resolution modification time of F</etc>, using
		2193	C<stat>, and C<IO::AIO::aio_stat>.
		2194
		2195	if (stat "/etc") {
		2196	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2197	}
		2198
		2199	IO::AIO::aio_stat "/etc", sub {
		2200	$_[0]
		2201	and return;
		2202
		2203	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2204	};
		2205
		2206	IO::AIO::flush;
		2207
		2208	Output of the awbove on my system, showing reduced and full accuracy:
		2209
		2210	stat(/etc) mtime: 1534043702.020808
		2211	aio_stat(/etc) mtime: 1534043702.020807792
		2212
		2213
1650	=head3 MISCELLANEOUS FUNCTIONS	2214	=head3 MISCELLANEOUS FUNCTIONS
1651		2215
1652	IO::AIO implements some functions that might be useful, but are not	2216	IO::AIO implements some functions that are useful when you want to use
1653	asynchronous.	2217	some "Advanced I/O" function not available to in Perl, without going the
		2218	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2219	counterpart.
1654		2220
1655	=over 4	2221	=over 4
		2222
		2223	=item $numfd = IO::AIO::get_fdlimit
		2224
		2225	Tries to find the current file descriptor limit and returns it, or
		2226	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2227	the highest valid file descriptor number.
		2228
		2229	=item IO::AIO::min_fdlimit [$numfd]
		2230
		2231	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2232	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2233	is missing, it will try to set a very high limit, although this is not
		2234	recommended when you know the actual minimum that you require.
		2235
		2236	If the limit cannot be raised enough, the function makes a best-effort
		2237	attempt to increase the limit as much as possible, using various
		2238	tricks, while still failing. You can query the resulting limit using
		2239	C<IO::AIO::get_fdlimit>.
		2240
		2241	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2242	true.
1656		2243
1657	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2244	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1658		2245
1659	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2246	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1660	but is blocking (this makes most sense if you know the input data is	2247	but is blocking (this makes most sense if you know the input data is
…		…
1665		2252
1666	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2253	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1667		2254
1668	Simply calls the C<posix_fadvise> function (see its	2255	Simply calls the C<posix_fadvise> function (see its
1669	manpage for details). The following advice constants are	2256	manpage for details). The following advice constants are
1670	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2257	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1671	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2258	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1672	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2259	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1673		2260
1674	On systems that do not implement C<posix_fadvise>, this function returns	2261	On systems that do not implement C<posix_fadvise>, this function returns
1675	ENOSYS, otherwise the return value of C<posix_fadvise>.	2262	ENOSYS, otherwise the return value of C<posix_fadvise>.
1676		2263
1677	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2264	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1678		2265
1679	Simply calls the C<posix_madvise> function (see its	2266	Simply calls the C<posix_madvise> function (see its
1680	manpage for details). The following advice constants are	2267	manpage for details). The following advice constants are
1681	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2268	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1682	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2269	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2270	C<IO::AIO::MADV_DONTNEED>.
		2271
		2272	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2273	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2274	will be reduced to fit into the C<$scalar>.
1683		2275
1684	On systems that do not implement C<posix_madvise>, this function returns	2276	On systems that do not implement C<posix_madvise>, this function returns
1685	ENOSYS, otherwise the return value of C<posix_madvise>.	2277	ENOSYS, otherwise the return value of C<posix_madvise>.
1686		2278
1687	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2279	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1688		2280
1689	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2281	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1690	$scalar (see its manpage for details). The following protect	2282	$scalar (see its manpage for details). The following protect
1691	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2283	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1692	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2284	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2285
		2286	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2287	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2288	will be reduced to fit into the C<$scalar>.
1693		2289
1694	On systems that do not implement C<mprotect>, this function returns	2290	On systems that do not implement C<mprotect>, this function returns
1695	ENOSYS, otherwise the return value of C<mprotect>.	2291	ENOSYS, otherwise the return value of C<mprotect>.
1696		2292
1697	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2293	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1698		2294
1699	Memory-maps a file (or anonymous memory range) and attaches it to the	2295	Memory-maps a file (or anonymous memory range) and attaches it to the
1700	given C<$scalar>, which will act like a string scalar.	2296	given C<$scalar>, which will act like a string scalar. Returns true on
		2297	success, and false otherwise.
1701		2298
		2299	The scalar must exist, but its contents do not matter - this means you
		2300	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2301	the scalar first.
		2302
1702	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2303	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1703	change the string length, and most read-only operations such as copying it	2304	which don't change the string length, and most read-only operations such
1704	or searching it with regexes and so on.	2305	as copying it or searching it with regexes and so on.
1705		2306
1706	Anything else is unsafe and will, at best, result in memory leaks.	2307	Anything else is unsafe and will, at best, result in memory leaks.
1707		2308
1708	The memory map associated with the C<$scalar> is automatically removed	2309	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	2310	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1710	C<IO::AIO::munmap> functions are called.	2311	or C<IO::AIO::munmap> functions are called on it.
1711		2312
1712	This calls the C<mmap>(2) function internally. See your system's manual	2313	This calls the C<mmap>(2) function internally. See your system's manual
1713	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2314	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1714		2315
1715	The C<$length> must be larger than zero and smaller than the actual	2316	The C<$length> must be larger than zero and smaller than the actual
1716	filesize.	2317	filesize.
1717		2318
1718	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2319	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1719	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2320	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1720		2321
1721	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2322	C<$flags> can be a combination of
1722	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2323	C<IO::AIO::MAP_SHARED> or
1723	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2324	C<IO::AIO::MAP_PRIVATE>,
		2325	or a number of system-specific flags (when not available, the are C<0>):
1724	(which is set to C<MAP_ANON> if your system only provides this	2326	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1725	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2327	C<IO::AIO::MAP_LOCKED>,
1726	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2328	C<IO::AIO::MAP_NORESERVE>,
		2329	C<IO::AIO::MAP_POPULATE>,
1727	C<IO::AIO::MAP_NONBLOCK>	2330	C<IO::AIO::MAP_NONBLOCK>,
		2331	C<IO::AIO::MAP_FIXED>,
		2332	C<IO::AIO::MAP_GROWSDOWN>,
		2333	C<IO::AIO::MAP_32BIT>,
		2334	C<IO::AIO::MAP_HUGETLB>,
		2335	C<IO::AIO::MAP_STACK>,
		2336	C<IO::AIO::MAP_FIXED_NOREPLACE>,
		2337	C<IO::AIO::MAP_SHARED_VALIDATE>,
		2338	C<IO::AIO::MAP_SYNC> or
		2339	C<IO::AIO::MAP_UNINITIALIZED>.
1728		2340
1729	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2341	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1730		2342
1731	C<$offset> is the offset from the start of the file - it generally must be	2343	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>.	2344	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1746		2358
1747	=item IO::AIO::munmap $scalar	2359	=item IO::AIO::munmap $scalar
1748		2360
1749	Removes a previous mmap and undefines the C<$scalar>.	2361	Removes a previous mmap and undefines the C<$scalar>.
1750		2362
		2363	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2364
		2365	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2366	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2367	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2368
		2369	Returns true if successful, and false otherwise. If the underlying mmapped
		2370	region has changed address, then the true value has the numerical value
		2371	C<1>, otherwise it has the numerical value C<0>:
		2372
		2373	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2374	or die "mremap: $!";
		2375
		2376	if ($success*1) {
		2377	warn "scalar has chanegd address in memory\n";
		2378	}
		2379
		2380	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2381	implemented, but not supported and might go away in a future version.
		2382
		2383	On systems where this call is not supported or is not emulated, this call
		2384	returns falls and sets C<$!> to C<ENOSYS>.
		2385
		2386	=item IO::AIO::mlockall $flags
		2387
		2388	Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
		2389	but is blocking.
		2390
1751	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef	2391	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1752		2392
1753	Calls the C<munlock> function, undoing the effects of a previous	2393	Calls the C<munlock> function, undoing the effects of a previous
1754	C<aio_mlock> call (see its description for details).	2394	C<aio_mlock> call (see its description for details).
1755		2395
…		…
1757		2397
1758	Calls the C<munlockall> function.	2398	Calls the C<munlockall> function.
1759		2399
1760	On systems that do not implement C<munlockall>, this function returns	2400	On systems that do not implement C<munlockall>, this function returns
1761	ENOSYS, otherwise the return value of C<munlockall>.	2401	ENOSYS, otherwise the return value of C<munlockall>.
		2402
		2403	=item $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		2404
		2405	Uses the GNU/Linux C<accept4(2)> syscall, if available, to accept a socket
		2406	and return the new file handle on success, or sets C<$!> and returns
		2407	C<undef> on error.
		2408
		2409	The remote name of the new socket will be stored in C<$sockaddr>, which
		2410	will be extended to allow for at least C<$sockaddr_maxlen> octets. If the
		2411	socket name does not fit into C<$sockaddr_maxlen> octets, this is signaled
		2412	by returning a longer string in C<$sockaddr>, which might or might not be
		2413	truncated.
		2414
		2415	To accept name-less sockets, use C<undef> for C<$sockaddr> and C<0> for
		2416	C<$sockaddr_maxlen>.
		2417
		2418	The main reasons to use this syscall rather than portable C<accept(2)>
		2419	are that you can specify C<SOCK_NONBLOCK> and/or C<SOCK_CLOEXEC>
		2420	flags and you can accept name-less sockets by specifying C<0> for
		2421	C<$sockaddr_maxlen>, which is sadly not possible with perl's interface to
		2422	C<accept>.
		2423
		2424	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2425
		2426	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2427	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2428	should be the file offset.
		2429
		2430	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2431	silently corrupt the data in this case.
		2432
		2433	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2434	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2435	C<IO::AIO::SPLICE_F_GIFT>.
		2436
		2437	See the C<splice(2)> manpage for details.
		2438
		2439	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2440
		2441	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2442	description for C<IO::AIO::splice> above for details.
		2443
		2444	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2445
		2446	Attempts to query or change the pipe buffer size. Obviously works only
		2447	on pipes, and currently works only on GNU/Linux systems, and fails with
		2448	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2449	size on other systems, drop me a note.
		2450
		2451	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2452
		2453	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2454	C<$flags> is missing or C<0>, then this should be the same as a call to
		2455	perl's built-in C<pipe> function and create a new pipe, and works on
		2456	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2457	(..., 4096, O_BINARY)>.
		2458
		2459	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2460	the given flags (Linux 2.6.27, glibc 2.9).
		2461
		2462	On success, the read and write file handles are returned.
		2463
		2464	On error, nothing will be returned. If the pipe2 syscall is missing and
		2465	C<$flags> is non-zero, fails with C<ENOSYS>.
		2466
		2467	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2468	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2469	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2470
		2471	Example: create a pipe race-free w.r.t. threads and fork:
		2472
		2473	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2474	or die "pipe2: $!\n";
		2475
		2476	=item $fh = IO::AIO::memfd_create $pathname[, $flags]
		2477
		2478	This is a direct interface to the Linux L<memfd_create(2)> system
		2479	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2480	should be C<IO::AIO::MFD_CLOEXEC>.
		2481
		2482	On success, the new memfd filehandle is returned, otherwise returns
		2483	C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
		2484
		2485	Please refer to L<memfd_create(2)> for more info on this call.
		2486
		2487	The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
		2488	C<IO::AIO::MFD_ALLOW_SEALING> and C<IO::AIO::MFD_HUGETLB>.
		2489
		2490	Example: create a new memfd.
		2491
		2492	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2493	or die "memfd_create: $!\n";
		2494
		2495	=item $fh = IO::AIO::pidfd_open $pid[, $flags]
		2496
		2497	This is an interface to the Linux L<pidfd_open(2)> system call. The
		2498	default for C<$flags> is C<0>.
		2499
		2500	On success, a new pidfd filehandle is returned (that is already set to
		2501	close-on-exec), otherwise returns C<undef>. If the syscall is missing,
		2502	fails with C<ENOSYS>.
		2503
		2504	Example: open pid 6341 as pidfd.
		2505
		2506	my $fh = IO::AIO::pidfd_open 6341
		2507	or die "pidfd_open: $!\n";
		2508
		2509	=item $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		2510
		2511	This is an interface to the Linux L<pidfd_send_signal> system call. The
		2512	default for C<$siginfo> is C<undef> and the default for C<$flags> is C<0>.
		2513
		2514	Returns the system call status. If the syscall is missing, fails with
		2515	C<ENOSYS>.
		2516
		2517	When specified, C<$siginfo> must be a reference to a hash with one or more
		2518	of the following members:
		2519
		2520	=over
		2521
		2522	=item code - the C<si_code> member
		2523
		2524	=item pid - the C<si_pid> member
		2525
		2526	=item uid - the C<si_uid> member
		2527
		2528	=item value_int - the C<si_value.sival_int> member
		2529
		2530	=item value_ptr - the C<si_value.sival_ptr> member, specified as an integer
		2531
		2532	=back
		2533
		2534	Example: send a SIGKILL to the specified process.
		2535
		2536	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
		2537	and die "pidfd_send_signal: $!\n";
		2538
		2539	Example: send a SIGKILL to the specified process with extra data.
		2540
		2541	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
		2542	and die "pidfd_send_signal: $!\n";
		2543
		2544	=item $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		2545
		2546	This is an interface to the Linux L<pidfd_getfd> system call. The default
		2547	for C<$flags> is C<0>.
		2548
		2549	On success, returns a dup'ed copy of the target file descriptor (specified
		2550	as an integer) returned (that is already set to close-on-exec), otherwise
		2551	returns C<undef>. If the syscall is missing, fails with C<ENOSYS>.
		2552
		2553	Example: get a copy of standard error of another process and print soemthing to it.
		2554
		2555	my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
		2556	or die "pidfd_getfd: $!\n";
		2557	print $errfh "stderr\n";
		2558
		2559	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2560
		2561	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2562	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2563
		2564	On success, the new eventfd filehandle is returned, otherwise returns
		2565	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2566
		2567	Please refer to L<eventfd(2)> for more info on this call.
		2568
		2569	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2570	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2571
		2572	Example: create a new eventfd filehandle:
		2573
		2574	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2575	or die "eventfd: $!\n";
		2576
		2577	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2578
		2579	This is a direct interface to the Linux L<timerfd_create(2)> system
		2580	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2581	should be C<IO::AIO::TFD_CLOEXEC>.
		2582
		2583	On success, the new timerfd filehandle is returned, otherwise returns
		2584	C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
		2585
		2586	Please refer to L<timerfd_create(2)> for more info on this call.
		2587
		2588	The following C<$clockid> values are
		2589	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2590	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2591	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2592	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2593
		2594	The following C<$flags> values are available (Linux
		2595	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2596
		2597	Example: create a new timerfd and set it to one-second repeated alarms,
		2598	then wait for two alarms:
		2599
		2600	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2601	or die "timerfd_create: $!\n";
		2602
		2603	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2604	or die "timerfd_settime: $!\n";
		2605
		2606	for (1..2) {
		2607	8 == sysread $fh, my $buf, 8
		2608	or die "timerfd read failure\n";
		2609
		2610	printf "number of expirations (likely 1): %d\n",
		2611	unpack "Q", $buf;
		2612	}
		2613
		2614	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2615
		2616	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2617	call. Please refer to its manpage for more info on this call.
		2618
		2619	The new itimerspec is specified using two (possibly fractional) second
		2620	values, C<$new_interval> and C<$new_value>).
		2621
		2622	On success, the current interval and value are returned (as per
		2623	C<timerfd_gettime>). On failure, the empty list is returned.
		2624
		2625	The following C<$flags> values are
		2626	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2627	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2628
		2629	See C<IO::AIO::timerfd_create> for a full example.
		2630
		2631	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2632
		2633	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2634	call. Please refer to its manpage for more info on this call.
		2635
		2636	On success, returns the current values of interval and value for the given
		2637	timerfd (as potentially fractional second values). On failure, the empty
		2638	list is returned.
1762		2639
1763	=back	2640	=back
1764		2641
1765	=cut	2642	=cut
1766		2643
…		…
1804	=head2 FORK BEHAVIOUR	2681	=head2 FORK BEHAVIOUR
1805		2682
1806	Usage of pthreads in a program changes the semantics of fork	2683	Usage of pthreads in a program changes the semantics of fork
1807	considerably. Specifically, only async-safe functions can be called after	2684	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	2685	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,	2686	with defined behaviour in perl if pthreads are involved. IO::AIO uses
1810	but many other extensions and (for inexplicable reasons) perl itself often	2687	pthreads, so this applies, but many other extensions and (for inexplicable
1811	is linked against pthreads, so this limitation applies.	2688	reasons) perl itself often is linked against pthreads, so this limitation
		2689	applies to quite a lot of perls.
1812		2690
1813	Some operating systems have extensions that allow safe use of fork, and	2691	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	2692	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	2693	using IO::AIO in the child is not.
1816	to POSIX.	2694
		2695	You might get around by not I<using> IO::AIO before (or after)
		2696	forking. You could also try to call the L<IO::AIO::reinit> function in the
		2697	child:
		2698
		2699	=over 4
		2700
		2701	=item IO::AIO::reinit
		2702
		2703	Abandons all current requests and I/O threads and simply reinitialises all
		2704	data structures. This is not an operation supported by any standards, but
		2705	happens to work on GNU/Linux and some newer BSD systems.
		2706
		2707	The only reasonable use for this function is to call it after forking, if
		2708	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2709	the process will result in undefined behaviour. Calling it at any time
		2710	will also result in any undefined (by POSIX) behaviour.
		2711
		2712	=back
		2713
		2714	=head2 LINUX-SPECIFIC CALLS
		2715
		2716	When a call is documented as "linux-specific" then this means it
		2717	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2718	availability and compatibility of such calls regardless of the platform
		2719	it is compiled on, so platforms such as FreeBSD which often implement
		2720	these calls will work. When in doubt, call them and see if they fail wth
		2721	C<ENOSYS>.
1817		2722
1818	=head2 MEMORY USAGE	2723	=head2 MEMORY USAGE
1819		2724
1820	Per-request usage:	2725	Per-request usage:
1821		2726
…		…
1834	temporary buffers, and each thread requires a stack and other data	2739	temporary buffers, and each thread requires a stack and other data
1835	structures (usually around 16k-128k, depending on the OS).	2740	structures (usually around 16k-128k, depending on the OS).
1836		2741
1837	=head1 KNOWN BUGS	2742	=head1 KNOWN BUGS
1838		2743
1839	Known bugs will be fixed in the next release.	2744	Known bugs will be fixed in the next release :)
		2745
		2746	=head1 KNOWN ISSUES
		2747
		2748	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2749	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2750	non-created hash slots or other scalars I didn't think of. It's best to
		2751	avoid such and either use scalar variables or making sure that the scalar
		2752	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2753
		2754	I am not sure anything can be done about this, so this is considered a
		2755	known issue, rather than a bug.
1840		2756
1841	=head1 SEE ALSO	2757	=head1 SEE ALSO
1842		2758
1843	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2759	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1844	more natural syntax.	2760	more natural syntax and L<IO::FDPass> for file descriptor passing.
1845		2761
1846	=head1 AUTHOR	2762	=head1 AUTHOR
1847		2763
1848	Marc Lehmann <schmorp@schmorp.de>	2764	Marc Lehmann <schmorp@schmorp.de>
1849	http://home.schmorp.de/	2765	http://home.schmorp.de/

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