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Revision 1.212 by root, Thu Sep 29 22:42:15 2011 UTC vs.
Revision 1.315 by root, Mon Sep 5 00:03:32 2022 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	IO::AIO - Asynchronous Input/Output	3	IO::AIO - Asynchronous/Advanced Input/Output
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
…		…
58	not well-supported or restricted (GNU/Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
59	files currently, for example), and they would only support aio_read and	59	files currently, for example), and they would only support aio_read and
60	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
61	using threads anyway.	61	using threads anyway.
62		62
		63	In addition to asynchronous I/O, this module also exports some rather
		64	arcane interfaces, such as C<madvise> or linux's C<splice> system call,
		65	which is why the C<A> in C<AIO> can also mean I<advanced>.
		66
63	Although the module will work in the presence of other (Perl-) threads,	67	Although the module will work in the presence of other (Perl-) threads,
64	it is currently not reentrant in any way, so use appropriate locking	68	it is currently not reentrant in any way, so use appropriate locking
65	yourself, always call C<poll_cb> from within the same thread, or never	69	yourself, always call C<poll_cb> from within the same thread, or never
66	call C<poll_cb> (or other C<aio_> functions) recursively.	70	call C<poll_cb> (or other C<aio_> functions) recursively.
67		71
68	=head2 EXAMPLE	72	=head2 EXAMPLE
69		73
70	This is a simple example that uses the EV module and loads	74	This is a simple example that uses the EV module and loads
71	F</etc/passwd> asynchronously:	75	F</etc/passwd> asynchronously:
72		76
73	use Fcntl;
74	use EV;	77	use EV;
75	use IO::AIO;	78	use IO::AIO;
76		79
77	# register the IO::AIO callback with EV	80	# register the IO::AIO callback with EV
78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	81	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
…		…
95		98
96	# file contents now in $contents	99	# file contents now in $contents
97	print $contents;	100	print $contents;
98		101
99	# exit event loop and program	102	# exit event loop and program
100	EV::unloop;	103	EV::break;
101	};	104	};
102	};	105	};
103		106
104	# possibly queue up other requests, or open GUI windows,	107	# possibly queue up other requests, or open GUI windows,
105	# check for sockets etc. etc.	108	# check for sockets etc. etc.
106		109
107	# process events as long as there are some:	110	# process events as long as there are some:
108	EV::loop;	111	EV::run;
109		112
110	=head1 REQUEST ANATOMY AND LIFETIME	113	=head1 REQUEST ANATOMY AND LIFETIME
111		114
112	Every C<aio_*> function creates a request. which is a C data structure not	115	Every C<aio_*> function creates a request. which is a C data structure not
113	directly visible to Perl.	116	directly visible to Perl.
…		…
168	use common::sense;	171	use common::sense;
169		172
170	use base 'Exporter';	173	use base 'Exporter';
171		174
172	BEGIN {	175	BEGIN {
173	our $VERSION = '4.0';	176	our $VERSION = 4.77;
174		177
175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	178	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx	179	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate	181	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
179	aio_pathsync aio_readahead	182	aio_pathsync aio_readahead aio_fiemap aio_allocate
180	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
181	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	184	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
182	aio_chmod aio_utime aio_truncate	185	aio_chmod aio_utime aio_truncate
183	aio_msync aio_mtouch aio_mlock aio_mlockall	186	aio_msync aio_mtouch aio_mlock aio_mlockall
184	aio_statvfs	187	aio_statvfs
		188	aio_slurp
185	aio_wd);	189	aio_wd);
186		190
187	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	191	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
188	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	192	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
189	min_parallel max_parallel max_idle idle_timeout	193	min_parallel max_parallel max_idle idle_timeout
190	nreqs nready npending nthreads	194	nreqs nready npending nthreads
191	max_poll_time max_poll_reqs	195	max_poll_time max_poll_reqs
192	sendfile fadvise madvise	196	sendfile fadvise madvise
193	mmap munmap munlock munlockall);	197	mmap munmap mremap munlock munlockall
		198
		199	accept4 tee splice pipe2 pipesize
		200	fexecve memfd_create eventfd
		201	timerfd_create timerfd_settime timerfd_gettime
		202	pidfd_open pidfd_send_signal pidfd_getfd);
194		203
195	push @AIO_REQ, qw(aio_busy); # not exported	204	push @AIO_REQ, qw(aio_busy); # not exported
196		205
197	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	206	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
198		207
…		…
202		211
203	=head1 FUNCTIONS	212	=head1 FUNCTIONS
204		213
205	=head2 QUICK OVERVIEW	214	=head2 QUICK OVERVIEW
206		215
207	This section simply lists the prototypes of the most important functions	216	This section simply lists the prototypes most of the functions for
208	for quick reference. See the following sections for function-by-function	217	quick reference. See the following sections for function-by-function
209	documentation.	218	documentation.
210		219
211	aio_wd $pathname, $callback->($wd)	220	aio_wd $pathname, $callback->($wd)
212	aio_open $pathname, $flags, $mode, $callback->($fh)	221	aio_open $pathname, $flags, $mode, $callback->($fh)
213	aio_close $fh, $callback->($status)	222	aio_close $fh, $callback->($status)
		223	aio_seek $fh,$offset,$whence, $callback->($offs)
214	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	224	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
215	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	225	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
216	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	226	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
217	aio_readahead $fh,$offset,$length, $callback->($retval)	227	aio_readahead $fh,$offset,$length, $callback->($retval)
218	aio_stat $fh_or_path, $callback->($status)	228	aio_stat $fh_or_path, $callback->($status)
219	aio_lstat $fh, $callback->($status)	229	aio_lstat $fh, $callback->($status)
220	aio_statvfs $fh_or_path, $callback->($statvfs)	230	aio_statvfs $fh_or_path, $callback->($statvfs)
221	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	231	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
222	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	232	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		233	aio_chmod $fh_or_path, $mode, $callback->($status)
223	aio_truncate $fh_or_path, $offset, $callback->($status)	234	aio_truncate $fh_or_path, $offset, $callback->($status)
224	aio_chmod $fh_or_path, $mode, $callback->($status)	235	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		236	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
225	aio_unlink $pathname, $callback->($status)	237	aio_unlink $pathname, $callback->($status)
226	aio_mknod $pathname, $mode, $dev, $callback->($status)	238	aio_mknod $pathname, $mode, $dev, $callback->($status)
227	aio_link $srcpath, $dstpath, $callback->($status)	239	aio_link $srcpath, $dstpath, $callback->($status)
228	aio_symlink $srcpath, $dstpath, $callback->($status)	240	aio_symlink $srcpath, $dstpath, $callback->($status)
229	aio_readlink $pathname, $callback->($link)	241	aio_readlink $pathname, $callback->($link)
230	aio_realpath $pathname, $callback->($link)	242	aio_realpath $pathname, $callback->($path)
231	aio_rename $srcpath, $dstpath, $callback->($status)	243	aio_rename $srcpath, $dstpath, $callback->($status)
		244	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
232	aio_mkdir $pathname, $mode, $callback->($status)	245	aio_mkdir $pathname, $mode, $callback->($status)
233	aio_rmdir $pathname, $callback->($status)	246	aio_rmdir $pathname, $callback->($status)
234	aio_readdir $pathname, $callback->($entries)	247	aio_readdir $pathname, $callback->($entries)
235	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	248	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
236	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	249	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
237	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	250	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		251	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
238	aio_load $pathname, $data, $callback->($status)	252	aio_load $pathname, $data, $callback->($status)
239	aio_copy $srcpath, $dstpath, $callback->($status)	253	aio_copy $srcpath, $dstpath, $callback->($status)
240	aio_move $srcpath, $dstpath, $callback->($status)	254	aio_move $srcpath, $dstpath, $callback->($status)
241	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
242	aio_rmtree $pathname, $callback->($status)	255	aio_rmtree $pathname, $callback->($status)
		256	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		257	aio_ioctl $fh, $request, $buf, $callback->($status)
243	aio_sync $callback->($status)	258	aio_sync $callback->($status)
244	aio_syncfs $fh, $callback->($status)	259	aio_syncfs $fh, $callback->($status)
245	aio_fsync $fh, $callback->($status)	260	aio_fsync $fh, $callback->($status)
246	aio_fdatasync $fh, $callback->($status)	261	aio_fdatasync $fh, $callback->($status)
247	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	262	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
248	aio_pathsync $pathname, $callback->($status)	263	aio_pathsync $pathname, $callback->($status)
249	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	264	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
250	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	265	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
251	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	266	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
252	aio_mlockall $flags, $callback->($status)	267	aio_mlockall $flags, $callback->($status)
253	aio_group $callback->(...)	268	aio_group $callback->(...)
254	aio_nop $callback->()	269	aio_nop $callback->()
…		…
268	IO::AIO::idle_timeout $seconds	283	IO::AIO::idle_timeout $seconds
269	IO::AIO::max_outstanding $maxreqs	284	IO::AIO::max_outstanding $maxreqs
270	IO::AIO::nreqs	285	IO::AIO::nreqs
271	IO::AIO::nready	286	IO::AIO::nready
272	IO::AIO::npending	287	IO::AIO::npending
		288	IO::AIO::reinit
		289
		290	$nfd = IO::AIO::get_fdlimit
		291	IO::AIO::min_fdlimit $nfd
273		292
274	IO::AIO::sendfile $ofh, $ifh, $offset, $count	293	IO::AIO::sendfile $ofh, $ifh, $offset, $count
275	IO::AIO::fadvise $fh, $offset, $len, $advice	294	IO::AIO::fadvise $fh, $offset, $len, $advice
		295	IO::AIO::fexecve $fh, $argv, $envp
		296
		297	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		298	IO::AIO::munmap $scalar
		299	IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
276	IO::AIO::madvise $scalar, $offset, $length, $advice	300	IO::AIO::madvise $scalar, $offset, $length, $advice
277	IO::AIO::mprotect $scalar, $offset, $length, $protect	301	IO::AIO::mprotect $scalar, $offset, $length, $protect
278	IO::AIO::munlock $scalar, $offset = 0, $length = undef	302	IO::AIO::munlock $scalar, $offset = 0, $length = undef
279	IO::AIO::munlockall	303	IO::AIO::munlockall
280		304
281	=head2 AIO REQUEST FUNCTIONS	305	# stat extensions
		306	$counter = IO::AIO::st_gen
		307	$seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		308	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		309	$nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		310	$seconds = IO::AIO::st_btimesec
		311	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		312
		313	# very much unportable syscalls
		314	IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
		315	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		316	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		317
		318	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		319	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		320
		321	$fh = IO::AIO::eventfd [$initval, [$flags]]
		322	$fh = IO::AIO::memfd_create $pathname[, $flags]
		323
		324	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		325	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		326	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		327
		328	$fh = IO::AIO::pidfd_open $pid[, $flags]
		329	$status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		330	$fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		331
		332	=head2 API NOTES
282		333
283	All the C<aio_*> calls are more or less thin wrappers around the syscall	334	All the C<aio_*> calls are more or less thin wrappers around the syscall
284	with the same name (sans C<aio_>). The arguments are similar or identical,	335	with the same name (sans C<aio_>). The arguments are similar or identical,
285	and they all accept an additional (and optional) C<$callback> argument	336	and they all accept an additional (and optional) C<$callback> argument
286	which must be a code reference. This code reference will be called after	337	which must be a code reference. This code reference will be called after
…		…
317	correct contents.	368	correct contents.
318		369
319	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	370	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
320	handles correctly whether it is set or not.	371	handles correctly whether it is set or not.
321		372
		373	=head2 AIO REQUEST FUNCTIONS
		374
322	=over 4	375	=over 4
323		376
324	=item $prev_pri = aioreq_pri [$pri]	377	=item $prev_pri = aioreq_pri [$pri]
325		378
326	Returns the priority value that would be used for the next request and, if	379	Returns the priority value that would be used for the next request and, if
…		…
355		408
356		409
357	=item aio_open $pathname, $flags, $mode, $callback->($fh)	410	=item aio_open $pathname, $flags, $mode, $callback->($fh)
358		411
359	Asynchronously open or create a file and call the callback with a newly	412	Asynchronously open or create a file and call the callback with a newly
360	created filehandle for the file.	413	created filehandle for the file (or C<undef> in case of an error).
361		414
362	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	415	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
363	for an explanation.	416	for an explanation.
364		417
365	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	418	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
388	following POSIX and non-POSIX constants are available (missing ones on	441	following POSIX and non-POSIX constants are available (missing ones on
389	your system are, as usual, C<0>):	442	your system are, as usual, C<0>):
390		443
391	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,	444	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
392	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,	445	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
393	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.	446	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
394		447
395		448
396	=item aio_close $fh, $callback->($status)	449	=item aio_close $fh, $callback->($status)
397		450
398	Asynchronously close a file and call the callback with the result	451	Asynchronously close a file and call the callback with the result
…		…
408	Or in other words: the file descriptor will be closed, but it will not be	461	Or in other words: the file descriptor will be closed, but it will not be
409	free for reuse until the perl filehandle is closed.	462	free for reuse until the perl filehandle is closed.
410		463
411	=cut	464	=cut
412		465
		466	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		467
		468	Seeks the filehandle to the new C<$offset>, similarly to perl's
		469	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		470	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		471	C<IO::AIO::SEEK_END>).
		472
		473	The resulting absolute offset will be passed to the callback, or C<-1> in
		474	case of an error.
		475
		476	In theory, the C<$whence> constants could be different than the
		477	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		478	so don't panic.
		479
		480	As a GNU/Linux (and maybe Solaris) extension, also the constants
		481	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		482	could be found. No guarantees about suitability for use in C<aio_seek> or
		483	Perl's C<sysseek> can be made though, although I would naively assume they
		484	"just work".
		485
413	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	486	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
414		487
415	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	488	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
416		489
417	Reads or writes C<$length> bytes from or to the specified C<$fh> and	490	Reads or writes C<$length> bytes from or to the specified C<$fh> and
418	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	491	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
419	and calls the callback without the actual number of bytes read (or -1 on	492	calls the callback with the actual number of bytes transferred (or -1 on
420	error, just like the syscall).	493	error, just like the syscall).
421		494
422	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	495	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
423	offset plus the actual number of bytes read.	496	offset plus the actual number of bytes read.
424		497
…		…
482	As native sendfile syscalls (as practically any non-POSIX interface hacked	555	As native sendfile syscalls (as practically any non-POSIX interface hacked
483	together in a hurry to improve benchmark numbers) tend to be rather buggy	556	together in a hurry to improve benchmark numbers) tend to be rather buggy
484	on many systems, this implementation tries to work around some known bugs	557	on many systems, this implementation tries to work around some known bugs
485	in Linux and FreeBSD kernels (probably others, too), but that might fail,	558	in Linux and FreeBSD kernels (probably others, too), but that might fail,
486	so you really really should check the return value of C<aio_sendfile> -	559	so you really really should check the return value of C<aio_sendfile> -
487	fewre bytes than expected might have been transferred.	560	fewer bytes than expected might have been transferred.
488		561
489		562
490	=item aio_readahead $fh,$offset,$length, $callback->($retval)	563	=item aio_readahead $fh,$offset,$length, $callback->($retval)
491		564
492	C<aio_readahead> populates the page cache with data from a file so that	565	C<aio_readahead> populates the page cache with data from a file so that
…		…
496	whole pages, so that offset is effectively rounded down to a page boundary	569	whole pages, so that offset is effectively rounded down to a page boundary
497	and bytes are read up to the next page boundary greater than or equal to	570	and bytes are read up to the next page boundary greater than or equal to
498	(off-set+length). C<aio_readahead> does not read beyond the end of the	571	(off-set+length). C<aio_readahead> does not read beyond the end of the
499	file. The current file offset of the file is left unchanged.	572	file. The current file offset of the file is left unchanged.
500		573
501	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	574	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
502	emulated by simply reading the data, which would have a similar effect.	575	be emulated by simply reading the data, which would have a similar effect.
503		576
504		577
505	=item aio_stat $fh_or_path, $callback->($status)	578	=item aio_stat $fh_or_path, $callback->($status)
506		579
507	=item aio_lstat $fh, $callback->($status)	580	=item aio_lstat $fh, $callback->($status)
508		581
509	Works like perl's C<stat> or C<lstat> in void context. The callback will	582	Works almost exactly like perl's C<stat> or C<lstat> in void context. The
510	be called after the stat and the results will be available using C<stat _>	583	callback will be called after the stat and the results will be available
511	or C<-s _> etc...	584	using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
		585	and C<-T>).
512		586
513	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,	587	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
514	for an explanation.	588	for an explanation.
515		589
516	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	590	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
…		…
523	behaviour).	597	behaviour).
524		598
525	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,	599	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
526	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,	600	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
527	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.	601	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		602
		603	To access higher resolution stat timestamps, see L<SUBSECOND STAT TIME
		604	ACCESS>.
528		605
529	Example: Print the length of F</etc/passwd>:	606	Example: Print the length of F</etc/passwd>:
530		607
531	aio_stat "/etc/passwd", sub {	608	aio_stat "/etc/passwd", sub {
532	$_[0] and die "stat failed: $!";	609	$_[0] and die "stat failed: $!";
…		…
576	namemax => 255,	653	namemax => 255,
577	frsize => 1024,	654	frsize => 1024,
578	fsid => 1810	655	fsid => 1810
579	}	656	}
580		657
581
582	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	658	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
583		659
584	Works like perl's C<utime> function (including the special case of $atime	660	Works like perl's C<utime> function (including the special case of $atime
585	and $mtime being undef). Fractional times are supported if the underlying	661	and $mtime being undef). Fractional times are supported if the underlying
586	syscalls support them.	662	syscalls support them.
587		663
588	When called with a pathname, uses utimes(2) if available, otherwise	664	When called with a pathname, uses utimensat(2) or utimes(2) if available,
589	utime(2). If called on a file descriptor, uses futimes(2) if available,	665	otherwise utime(2). If called on a file descriptor, uses futimens(2)
590	otherwise returns ENOSYS, so this is not portable.	666	or futimes(2) if available, otherwise returns ENOSYS, so this is not
		667	portable.
591		668
592	Examples:	669	Examples:
593		670
594	# set atime and mtime to current time (basically touch(1)):	671	# set atime and mtime to current time (basically touch(1)):
595	aio_utime "path", undef, undef;	672	aio_utime "path", undef, undef;
…		…
613	=item aio_truncate $fh_or_path, $offset, $callback->($status)	690	=item aio_truncate $fh_or_path, $offset, $callback->($status)
614		691
615	Works like truncate(2) or ftruncate(2).	692	Works like truncate(2) or ftruncate(2).
616		693
617		694
		695	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		696
		697	Allocates or frees disk space according to the C<$mode> argument. See the
		698	linux C<fallocate> documentation for details.
		699
		700	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		701	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		702	to deallocate a file range.
		703
		704	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		705	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		706	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		707	to unshare shared blocks (see your L<fallocate(2)> manpage).
		708
		709	The file system block size used by C<fallocate> is presumably the
		710	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		711	can dictate other limitations.
		712
		713	If C<fallocate> isn't available or cannot be emulated (currently no
		714	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		715
		716
618	=item aio_chmod $fh_or_path, $mode, $callback->($status)	717	=item aio_chmod $fh_or_path, $mode, $callback->($status)
619		718
620	Works like perl's C<chmod> function.	719	Works like perl's C<chmod> function.
621		720
622		721
…		…
659		758
660		759
661	=item aio_realpath $pathname, $callback->($path)	760	=item aio_realpath $pathname, $callback->($path)
662		761
663	Asynchronously make the path absolute and resolve any symlinks in	762	Asynchronously make the path absolute and resolve any symlinks in
664	C<$path>. The resulting path only consists of directories (Same as	763	C<$path>. The resulting path only consists of directories (same as
665	L<Cwd::realpath>).	764	L<Cwd::realpath>).
666		765
667	This request can be used to get the absolute path of the current working	766	This request can be used to get the absolute path of the current working
668	directory by passing it a path of F<.> (a single dot).	767	directory by passing it a path of F<.> (a single dot).
669		768
670		769
671	=item aio_rename $srcpath, $dstpath, $callback->($status)	770	=item aio_rename $srcpath, $dstpath, $callback->($status)
672		771
673	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	772	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
674	rename(2) and call the callback with the result code.	773	rename(2) and call the callback with the result code.
		774
		775	On systems that support the AIO::WD working directory abstraction
		776	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		777	of failing, C<rename> is called on the absolute path of C<$wd>.
		778
		779
		780	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		781
		782	Basically a version of C<aio_rename> with an additional C<$flags>
		783	argument. Calling this with C<$flags=0> is the same as calling
		784	C<aio_rename>.
		785
		786	Non-zero flags are currently only supported on GNU/Linux systems that
		787	support renameat2. Other systems fail with C<ENOSYS> in this case.
		788
		789	The following constants are available (missing ones are, as usual C<0>),
		790	see renameat2(2) for details:
		791
		792	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		793	and C<IO::AIO::RENAME_WHITEOUT>.
675		794
676		795
677	=item aio_mkdir $pathname, $mode, $callback->($status)	796	=item aio_mkdir $pathname, $mode, $callback->($status)
678		797
679	Asynchronously mkdir (create) a directory and call the callback with	798	Asynchronously mkdir (create) a directory and call the callback with
…		…
684	=item aio_rmdir $pathname, $callback->($status)	803	=item aio_rmdir $pathname, $callback->($status)
685		804
686	Asynchronously rmdir (delete) a directory and call the callback with the	805	Asynchronously rmdir (delete) a directory and call the callback with the
687	result code.	806	result code.
688		807
		808	On systems that support the AIO::WD working directory abstraction
		809	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		810	C<rmdir> is called on the absolute path of C<$wd>.
		811
689		812
690	=item aio_readdir $pathname, $callback->($entries)	813	=item aio_readdir $pathname, $callback->($entries)
691		814
692	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	815	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
693	directory (i.e. opendir + readdir + closedir). The entries will not be	816	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
708		831
709	=over 4	832	=over 4
710		833
711	=item IO::AIO::READDIR_DENTS	834	=item IO::AIO::READDIR_DENTS
712		835
713	When this flag is off, then the callback gets an arrayref consisting of	836	Normally the callback gets an arrayref consisting of names only (as
714	names only (as with C<aio_readdir>), otherwise it gets an arrayref with	837	with C<aio_readdir>). If this flag is set, then the callback gets an
715	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	838	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
716	entry in more detail.	839	single directory entry in more detail:
717		840
718	C<$name> is the name of the entry.	841	C<$name> is the name of the entry.
719		842
720	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	843	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
721		844
722	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	845	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
723	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	846	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
724	C<IO::AIO::DT_WHT>.	847	C<IO::AIO::DT_WHT>.
725		848
726	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	849	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
727	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	850	to know, you have to run stat yourself. Also, for speed/memory reasons,
728	scalars are read-only: you can not modify them.	851	the C<$type> scalars are read-only: you must not modify them.
729		852
730	C<$inode> is the inode number (which might not be exact on systems with 64	853	C<$inode> is the inode number (which might not be exact on systems with 64
731	bit inode numbers and 32 bit perls). This field has unspecified content on	854	bit inode numbers and 32 bit perls). This field has unspecified content on
732	systems that do not deliver the inode information.	855	systems that do not deliver the inode information.
733		856
…		…
744	short names are tried first.	867	short names are tried first.
745		868
746	=item IO::AIO::READDIR_STAT_ORDER	869	=item IO::AIO::READDIR_STAT_ORDER
747		870
748	When this flag is set, then the names will be returned in an order	871	When this flag is set, then the names will be returned in an order
749	suitable for stat()'ing each one. That is, when you plan to stat()	872	suitable for stat()'ing each one. That is, when you plan to stat() most or
750	all files in the given directory, then the returned order will likely	873	all files in the given directory, then the returned order will likely be
751	be fastest.	874	faster.
752		875
753	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then	876	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
754	the likely dirs come first, resulting in a less optimal stat order.	877	then the likely dirs come first, resulting in a less optimal stat order
		878	for stat'ing all entries, but likely a more optimal order for finding
		879	subdirectories.
755		880
756	=item IO::AIO::READDIR_FOUND_UNKNOWN	881	=item IO::AIO::READDIR_FOUND_UNKNOWN
757		882
758	This flag should not be set when calling C<aio_readdirx>. Instead, it	883	This flag should not be set when calling C<aio_readdirx>. Instead, it
759	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	884	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
…		…
761	C<$type>'s are known, which can be used to speed up some algorithms.	886	C<$type>'s are known, which can be used to speed up some algorithms.
762		887
763	=back	888	=back
764		889
765		890
		891	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		892
		893	Opens, reads and closes the given file. The data is put into C<$data>,
		894	which is resized as required.
		895
		896	If C<$offset> is negative, then it is counted from the end of the file.
		897
		898	If C<$length> is zero, then the remaining length of the file is
		899	used. Also, in this case, the same limitations to modifying C<$data> apply
		900	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		901	with C<substr>. If the size of the file is known, specifying a non-zero
		902	C<$length> results in a performance advantage.
		903
		904	This request is similar to the older C<aio_load> request, but since it is
		905	a single request, it might be more efficient to use.
		906
		907	Example: load F</etc/passwd> into C<$passwd>.
		908
		909	my $passwd;
		910	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		911	$_[0] >= 0
		912	or die "/etc/passwd: $!\n";
		913
		914	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		915	print $passwd;
		916	};
		917	IO::AIO::flush;
		918
		919
766	=item aio_load $pathname, $data, $callback->($status)	920	=item aio_load $pathname, $data, $callback->($status)
767		921
768	This is a composite request that tries to fully load the given file into	922	This is a composite request that tries to fully load the given file into
769	memory. Status is the same as with aio_read.	923	memory. Status is the same as with aio_read.
		924
		925	Using C<aio_slurp> might be more efficient, as it is a single request.
770		926
771	=cut	927	=cut
772		928
773	sub aio_load($$;$) {	929	sub aio_load($$;$) {
774	my ($path, undef, $cb) = @_;	930	my ($path, undef, $cb) = @_;
…		…
794	=item aio_copy $srcpath, $dstpath, $callback->($status)	950	=item aio_copy $srcpath, $dstpath, $callback->($status)
795		951
796	Try to copy the I<file> (directories not supported as either source or	952	Try to copy the I<file> (directories not supported as either source or
797	destination) from C<$srcpath> to C<$dstpath> and call the callback with	953	destination) from C<$srcpath> to C<$dstpath> and call the callback with
798	a status of C<0> (ok) or C<-1> (error, see C<$!>).	954	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		955
		956	Existing destination files will be truncated.
799		957
800	This is a composite request that creates the destination file with	958	This is a composite request that creates the destination file with
801	mode 0200 and copies the contents of the source file into it using	959	mode 0200 and copies the contents of the source file into it using
802	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	960	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
803	uid/gid, in that order.	961	uid/gid, in that order.
…		…
913	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1071	Scans a directory (similar to C<aio_readdir>) but additionally tries to
914	efficiently separate the entries of directory C<$path> into two sets of	1072	efficiently separate the entries of directory C<$path> into two sets of
915	names, directories you can recurse into (directories), and ones you cannot	1073	names, directories you can recurse into (directories), and ones you cannot
916	recurse into (everything else, including symlinks to directories).	1074	recurse into (everything else, including symlinks to directories).
917		1075
918	C<aio_scandir> is a composite request that creates of many sub requests_	1076	C<aio_scandir> is a composite request that generates many sub requests.
919	C<$maxreq> specifies the maximum number of outstanding aio requests that	1077	C<$maxreq> specifies the maximum number of outstanding aio requests that
920	this function generates. If it is C<< <= 0 >>, then a suitable default	1078	this function generates. If it is C<< <= 0 >>, then a suitable default
921	will be chosen (currently 4).	1079	will be chosen (currently 4).
922		1080
923	On error, the callback is called without arguments, otherwise it receives	1081	On error, the callback is called without arguments, otherwise it receives
…		…
987	aioreq_pri $pri;	1145	aioreq_pri $pri;
988	add $grp aio_stat $wd, sub {	1146	add $grp aio_stat $wd, sub {
989	return $grp->result () if $_[0];	1147	return $grp->result () if $_[0];
990	my $now = time;	1148	my $now = time;
991	my $hash1 = join ":", (stat _)[0,1,3,7,9];	1149	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		1150	my $rdxflags = READDIR_DIRS_FIRST;
		1151
		1152	if ((stat _)[3] < 2) {
		1153	# at least one non-POSIX filesystem exists
		1154	# that returns useful DT_type values: btrfs,
		1155	# so optimise for this here by requesting dents
		1156	$rdxflags |= READDIR_DENTS;
		1157	}
992		1158
993	# read the directory entries	1159	# read the directory entries
994	aioreq_pri $pri;	1160	aioreq_pri $pri;
995	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {	1161	add $grp aio_readdirx $wd, $rdxflags, sub {
996	my $entries = shift	1162	my ($entries, $flags) = @_
997	or return $grp->result ();	1163	or return $grp->result ();
		1164
		1165	if ($rdxflags & READDIR_DENTS) {
		1166	# if we requested type values, see if we can use them directly.
		1167
		1168	# if there were any DT_UNKNOWN entries then we assume we
		1169	# don't know. alternatively, we could assume that if we get
		1170	# one DT_DIR, then all directories are indeed marked with
		1171	# DT_DIR, but this seems not required for btrfs, and this
		1172	# is basically the "btrfs can't get it's act together" code
		1173	# branch.
		1174	unless ($flags & READDIR_FOUND_UNKNOWN) {
		1175	# now we have valid DT_ information for all entries,
		1176	# so use it as an optimisation without further stat's.
		1177	# they must also all be at the beginning of @$entries
		1178	# by now.
		1179
		1180	my $dirs;
		1181
		1182	if (@$entries) {
		1183	for (0 .. $#$entries) {
		1184	if ($entries->[$_][1] != DT_DIR) {
		1185	# splice out directories
		1186	$dirs = [splice @$entries, 0, $_];
		1187	last;
		1188	}
		1189	}
		1190
		1191	# if we didn't find any non-dir, then all entries are dirs
		1192	unless ($dirs) {
		1193	($dirs, $entries) = ($entries, []);
		1194	}
		1195	} else {
		1196	# directory is empty, so there are no sbdirs
		1197	$dirs = [];
		1198	}
		1199
		1200	# either splice'd the directories out or the dir was empty.
		1201	# convert dents to filenames
		1202	$_ = $_->[0] for @$dirs;
		1203	$_ = $_->[0] for @$entries;
		1204
		1205	return $grp->result ($dirs, $entries);
		1206	}
		1207
		1208	# cannot use, so return to our old ways
		1209	# by pretending we only scanned for names.
		1210	$_ = $_->[0] for @$entries;
		1211	}
998		1212
999	# stat the dir another time	1213	# stat the dir another time
1000	aioreq_pri $pri;	1214	aioreq_pri $pri;
1001	add $grp aio_stat $wd, sub {	1215	add $grp aio_stat $wd, sub {
1002	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1216	my $hash2 = join ":", (stat _)[0,1,3,7,9];
…		…
1057	}	1271	}
1058		1272
1059	=item aio_rmtree $pathname, $callback->($status)	1273	=item aio_rmtree $pathname, $callback->($status)
1060		1274
1061	Delete a directory tree starting (and including) C<$path>, return the	1275	Delete a directory tree starting (and including) C<$path>, return the
1062	status of the final C<rmdir> only. This is a composite request that	1276	status of the final C<rmdir> only. This is a composite request that
1063	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1277	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1064	everything else.	1278	everything else.
1065		1279
1066	=cut	1280	=cut
1067		1281
…		…
1088	add $grp $dirgrp;	1302	add $grp $dirgrp;
1089	};	1303	};
1090		1304
1091	$grp	1305	$grp
1092	}	1306	}
		1307
		1308	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1309
		1310	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1311
		1312	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1313	they execute asynchronously and pass the return value to the callback.
		1314
		1315	Both calls can be used for a lot of things, some of which make more sense
		1316	to run asynchronously in their own thread, while some others make less
		1317	sense. For example, calls that block waiting for external events, such
		1318	as locking, will also lock down an I/O thread while it is waiting, which
		1319	can deadlock the whole I/O system. At the same time, there might be no
		1320	alternative to using a thread to wait.
		1321
		1322	So in general, you should only use these calls for things that do
		1323	(filesystem) I/O, not for things that wait for other events (network,
		1324	other processes), although if you are careful and know what you are doing,
		1325	you still can.
		1326
		1327	The following constants are available and can be used for normal C<ioctl>
		1328	and C<fcntl> as well (missing ones are, as usual C<0>):
		1329
		1330	C<F_DUPFD_CLOEXEC>,
		1331
		1332	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1333
		1334	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1335
		1336	C<F_ADD_SEALS>, C<F_GET_SEALS>, C<F_SEAL_SEAL>, C<F_SEAL_SHRINK>, C<F_SEAL_GROW> and
		1337	C<F_SEAL_WRITE>.
		1338
		1339	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1340	C<FS_IOC_FIEMAP>.
		1341
		1342	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1343	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1344
		1345	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1346	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1347	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1348	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1349	C<FS_FL_USER_MODIFIABLE>.
		1350
		1351	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1352	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1353	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1354	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
1093		1355
1094	=item aio_sync $callback->($status)	1356	=item aio_sync $callback->($status)
1095		1357
1096	Asynchronously call sync and call the callback when finished.	1358	Asynchronously call sync and call the callback when finished.
1097		1359
…		…
1166	};	1428	};
1167		1429
1168	$grp	1430	$grp
1169	}	1431	}
1170		1432
1171	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1433	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1172		1434
1173	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1435	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1174	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1436	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1175	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1437	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1176	scalar must only be modified in-place while an aio operation is pending on	1438	scalar must only be modified in-place while an aio operation is pending on
…		…
1178		1440
1179	It calls the C<msync> function of your OS, if available, with the memory	1441	It calls the C<msync> function of your OS, if available, with the memory
1180	area starting at C<$offset> in the string and ending C<$length> bytes	1442	area starting at C<$offset> in the string and ending C<$length> bytes
1181	later. If C<$length> is negative, counts from the end, and if C<$length>	1443	later. If C<$length> is negative, counts from the end, and if C<$length>
1182	is C<undef>, then it goes till the end of the string. The flags can be	1444	is C<undef>, then it goes till the end of the string. The flags can be
1183	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1445	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1184	C<IO::AIO::MS_SYNC>.	1446	C<IO::AIO::MS_INVALIDATE>.
1185		1447
1186	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1448	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1187		1449
1188	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1450	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1189	scalars.	1451	scalars.
1190		1452
1191	It touches (reads or writes) all memory pages in the specified	1453	It touches (reads or writes) all memory pages in the specified
1192	range inside the scalar. All caveats and parameters are the same	1454	range inside the scalar. All caveats and parameters are the same
1193	as for C<aio_msync>, above, except for flags, which must be either	1455	as for C<aio_msync>, above, except for flags, which must be either
1194	C<0> (which reads all pages and ensures they are instantiated) or	1456	C<0> (which reads all pages and ensures they are instantiated) or
1195	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1457	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1196	writing an octet from it, which dirties the page).	1458	writing an octet from it, which dirties the page).
1197		1459
1198	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1460	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1199		1461
1200	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1462	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1219	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;	1481	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1220	aio_mlock $data; # mlock in background	1482	aio_mlock $data; # mlock in background
1221		1483
1222	=item aio_mlockall $flags, $callback->($status)	1484	=item aio_mlockall $flags, $callback->($status)
1223		1485
1224	Calls the C<mlockall> function with the given C<$flags> (a combination of	1486	Calls the C<mlockall> function with the given C<$flags> (a
1225	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).	1487	combination of C<IO::AIO::MCL_CURRENT>, C<IO::AIO::MCL_FUTURE> and
		1488	C<IO::AIO::MCL_ONFAULT>).
1226		1489
1227	On systems that do not implement C<mlockall>, this function returns C<-1>	1490	On systems that do not implement C<mlockall>, this function returns C<-1>
1228	and sets errno to C<ENOSYS>.	1491	and sets errno to C<ENOSYS>. Similarly, flag combinations not supported
		1492	by the system result in a return value of C<-1> with errno being set to
		1493	C<EINVAL>.
1229		1494
1230	Note that the corresponding C<munlockall> is synchronous and is	1495	Note that the corresponding C<munlockall> is synchronous and is
1231	documented under L<MISCELLANEOUS FUNCTIONS>.	1496	documented under L<MISCELLANEOUS FUNCTIONS>.
1232		1497
1233	Example: asynchronously lock all current and future pages into memory.	1498	Example: asynchronously lock all current and future pages into memory.
1234		1499
1235	aio_mlockall IO::AIO::MCL_FUTURE;	1500	aio_mlockall IO::AIO::MCL_FUTURE;
		1501
		1502	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1503
		1504	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1505	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1506	the ioctl is not available on your OS, then this request will fail with
		1507	C<ENOSYS>.
		1508
		1509	C<$start> is the starting offset to query extents for, C<$length> is the
		1510	size of the range to query - if it is C<undef>, then the whole file will
		1511	be queried.
		1512
		1513	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1514	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1515	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1516	the data portion.
		1517
		1518	C<$count> is the maximum number of extent records to return. If it is
		1519	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1520	case, if it is C<0>, then the callback receives the number of extents
		1521	instead of the extents themselves (which is unreliable, see below).
		1522
		1523	If an error occurs, the callback receives no arguments. The special
		1524	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1525
		1526	Otherwise, the callback receives an array reference with extent
		1527	structures. Each extent structure is an array reference itself, with the
		1528	following members:
		1529
		1530	[$logical, $physical, $length, $flags]
		1531
		1532	Flags is any combination of the following flag values (typically either C<0>
		1533	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1534
		1535	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1536	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1537	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1538	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1539	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1540	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1541
		1542	At the time of this writing (Linux 3.2), this request is unreliable unless
		1543	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1544	it to return all extents of a range for files with a large number of
		1545	extents. The code (only) works around all these issues if C<$count> is
		1546	C<undef>.
1236		1547
1237	=item aio_group $callback->(...)	1548	=item aio_group $callback->(...)
1238		1549
1239	This is a very special aio request: Instead of doing something, it is a	1550	This is a very special aio request: Instead of doing something, it is a
1240	container for other aio requests, which is useful if you want to bundle	1551	container for other aio requests, which is useful if you want to bundle
…		…
1304	object. This object stores the canonicalised, absolute version of the	1615	object. This object stores the canonicalised, absolute version of the
1305	path, and on systems that allow it, also a directory file descriptor.	1616	path, and on systems that allow it, also a directory file descriptor.
1306		1617
1307	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>	1618	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1308	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD	1619	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1309	object and a pathname instead. If the pathname is absolute, the	1620	object and a pathname instead (or the IO::AIO::WD object alone, which
		1621	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1310	IO::AIO::WD objetc is ignored, otherwise the pathname is resolved relative	1622	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1311	to that IO::AIO::WD object.	1623	to that IO::AIO::WD object.
1312		1624
1313	For example, to get a wd object for F</etc> and then stat F<passwd>	1625	For example, to get a wd object for F</etc> and then stat F<passwd>
1314	inside, you would write:	1626	inside, you would write:
1315		1627
…		…
1323	aio_stat [$etcdir, "passwd"], sub {	1635	aio_stat [$etcdir, "passwd"], sub {
1324	# yay	1636	# yay
1325	};	1637	};
1326	};	1638	};
1327		1639
		1640	The fact that C<aio_wd> is a request and not a normal function shows that
1328	This shows that creating an IO::AIO::WD object is itself a potentially	1641	creating an IO::AIO::WD object is itself a potentially blocking operation,
1329	blocking operation, which is why it is done asynchronously.	1642	which is why it is done asynchronously.
		1643
		1644	To stat the directory obtained with C<aio_wd> above, one could write
		1645	either of the following three request calls:
		1646
		1647	aio_lstat "/etc" , sub { ... # pathname as normal string
		1648	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1649	aio_lstat $wd , sub { ... # shorthand for the previous
1330		1650
1331	As with normal pathnames, IO::AIO keeps a copy of the working directory	1651	As with normal pathnames, IO::AIO keeps a copy of the working directory
1332	object and the pathname string, so you could write the following without	1652	object and the pathname string, so you could write the following without
1333	causing any issues due to C<$path> getting reused:	1653	causing any issues due to C<$path> getting reused:
1334		1654
…		…
1344	There are some caveats: when directories get renamed (or deleted), the	1664	There are some caveats: when directories get renamed (or deleted), the
1345	pathname string doesn't change, so will point to the new directory (or	1665	pathname string doesn't change, so will point to the new directory (or
1346	nowhere at all), while the directory fd, if available on the system,	1666	nowhere at all), while the directory fd, if available on the system,
1347	will still point to the original directory. Most functions accepting a	1667	will still point to the original directory. Most functions accepting a
1348	pathname will use the directory fd on newer systems, and the string on	1668	pathname will use the directory fd on newer systems, and the string on
1349	older systems. Some functions (such as realpath) will always rely on the	1669	older systems. Some functions (such as C<aio_realpath>) will always rely on
1350	string form of the pathname.	1670	the string form of the pathname.
1351		1671
1352	So this fucntionality is mainly useful to get some protection against	1672	So this functionality is mainly useful to get some protection against
1353	C<chdir>, to easily get an absolute path out of a relative path for future	1673	C<chdir>, to easily get an absolute path out of a relative path for future
1354	reference, and to speed up doing many operations in the same directory	1674	reference, and to speed up doing many operations in the same directory
1355	(e.g. when stat'ing all files in a directory).	1675	(e.g. when stat'ing all files in a directory).
1356		1676
1357	The following functions implement this working directory abstraction:	1677	The following functions implement this working directory abstraction:
…		…
1370	passing C<undef> as working directory component of a pathname fails the	1690	passing C<undef> as working directory component of a pathname fails the
1371	request with C<ENOENT>, there is often no need for error checking in the	1691	request with C<ENOENT>, there is often no need for error checking in the
1372	C<aio_wd> callback, as future requests using the value will fail in the	1692	C<aio_wd> callback, as future requests using the value will fail in the
1373	expected way.	1693	expected way.
1374		1694
1375	If this call isn't available because your OS lacks it or it couldn't be
1376	detected, it will be emulated by calling C<fsync> instead.
1377
1378	=item IO::AIO::CWD	1695	=item IO::AIO::CWD
1379		1696
1380	This is a compiletime constant (object) that represents the process	1697	This is a compile time constant (object) that represents the process
1381	current working directory.	1698	current working directory.
1382		1699
1383	Specifying this object as working directory object for a pathname is as	1700	Specifying this object as working directory object for a pathname is as if
1384	if the pathname would be specified directly, without a directory object,	1701	the pathname would be specified directly, without a directory object. For
1385	e.g., these calls are functionally identical:	1702	example, these calls are functionally identical:
1386		1703
1387	aio_stat "somefile", sub { ... };	1704	aio_stat "somefile", sub { ... };
1388	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };	1705	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1389		1706
1390	=back	1707	=back
1391		1708
		1709	To recover the path associated with an IO::AIO::WD object, you can use
		1710	C<aio_realpath>:
		1711
		1712	aio_realpath $wd, sub {
		1713	warn "path is $_[0]\n";
		1714	};
		1715
		1716	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1717	sometimes, fall back to using an absolue path.
1392		1718
1393	=head2 IO::AIO::REQ CLASS	1719	=head2 IO::AIO::REQ CLASS
1394		1720
1395	All non-aggregate C<aio_*> functions return an object of this class when	1721	All non-aggregate C<aio_*> functions return an object of this class when
1396	called in non-void context.	1722	called in non-void context.
…		…
1557	The default value for the limit is C<0>, but note that setting a feeder	1883	The default value for the limit is C<0>, but note that setting a feeder
1558	automatically bumps it up to C<2>.	1884	automatically bumps it up to C<2>.
1559		1885
1560	=back	1886	=back
1561		1887
		1888
1562	=head2 SUPPORT FUNCTIONS	1889	=head2 SUPPORT FUNCTIONS
1563		1890
1564	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1891	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1565		1892
1566	=over 4	1893	=over 4
…		…
1574		1901
1575	See C<poll_cb> for an example.	1902	See C<poll_cb> for an example.
1576		1903
1577	=item IO::AIO::poll_cb	1904	=item IO::AIO::poll_cb
1578		1905
1579	Process some outstanding events on the result pipe. You have to call	1906	Process some requests that have reached the result phase (i.e. they have
		1907	been executed but the results are not yet reported). You have to call
		1908	this "regularly" to finish outstanding requests.
		1909
1580	this regularly. Returns C<0> if all events could be processed (or there	1910	Returns C<0> if all events could be processed (or there were no
1581	were no events to process), or C<-1> if it returned earlier for whatever	1911	events to process), or C<-1> if it returned earlier for whatever
1582	reason. Returns immediately when no events are outstanding. The amount of	1912	reason. Returns immediately when no events are outstanding. The amount
1583	events processed depends on the settings of C<IO::AIO::max_poll_req> and	1913	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1584	C<IO::AIO::max_poll_time>.	1914	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1585		1915
1586	If not all requests were processed for whatever reason, the filehandle	1916	If not all requests were processed for whatever reason, the poll file
1587	will still be ready when C<poll_cb> returns, so normally you don't have to	1917	descriptor will still be ready when C<poll_cb> returns, so normally you
1588	do anything special to have it called later.	1918	don't have to do anything special to have it called later.
1589		1919
1590	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1920	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1591	ready, it can be beneficial to call this function from loops which submit	1921	ready, it can be beneficial to call this function from loops which submit
1592	a lot of requests, to make sure the results get processed when they become	1922	a lot of requests, to make sure the results get processed when they become
1593	available and not just when the loop is finished and the event loop takes	1923	available and not just when the loop is finished and the event loop takes
…		…
1602	poll => 'r', async => 1,	1932	poll => 'r', async => 1,
1603	cb => \&IO::AIO::poll_cb);	1933	cb => \&IO::AIO::poll_cb);
1604		1934
1605	=item IO::AIO::poll_wait	1935	=item IO::AIO::poll_wait
1606		1936
1607	If there are any outstanding requests and none of them in the result	1937	Wait until either at least one request is in the result phase or no
1608	phase, wait till the result filehandle becomes ready for reading (simply	1938	requests are outstanding anymore.
1609	does a C<select> on the filehandle. This is useful if you want to	1939
1610	synchronously wait for some requests to finish).	1940	This is useful if you want to synchronously wait for some requests to
		1941	become ready, without actually handling them.
1611		1942
1612	See C<nreqs> for an example.	1943	See C<nreqs> for an example.
1613		1944
1614	=item IO::AIO::poll	1945	=item IO::AIO::poll
1615		1946
…		…
1626		1957
1627	Strictly equivalent to:	1958	Strictly equivalent to:
1628		1959
1629	IO::AIO::poll_wait, IO::AIO::poll_cb	1960	IO::AIO::poll_wait, IO::AIO::poll_cb
1630	while IO::AIO::nreqs;	1961	while IO::AIO::nreqs;
		1962
		1963	This function can be useful at program aborts, to make sure outstanding
		1964	I/O has been done (C<IO::AIO> uses an C<END> block which already calls
		1965	this function on normal exits), or when you are merely using C<IO::AIO>
		1966	for its more advanced functions, rather than for async I/O, e.g.:
		1967
		1968	my ($dirs, $nondirs);
		1969	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1970	IO::AIO::flush;
		1971	# $dirs, $nondirs are now set
1631		1972
1632	=item IO::AIO::max_poll_reqs $nreqs	1973	=item IO::AIO::max_poll_reqs $nreqs
1633		1974
1634	=item IO::AIO::max_poll_time $seconds	1975	=item IO::AIO::max_poll_time $seconds
1635		1976
…		…
1662	poll => 'r', nice => 1,	2003	poll => 'r', nice => 1,
1663	cb => &IO::AIO::poll_cb);	2004	cb => &IO::AIO::poll_cb);
1664		2005
1665	=back	2006	=back
1666		2007
		2008
1667	=head3 CONTROLLING THE NUMBER OF THREADS	2009	=head3 CONTROLLING THE NUMBER OF THREADS
1668		2010
1669	=over	2011	=over
1670		2012
1671	=item IO::AIO::min_parallel $nthreads	2013	=item IO::AIO::min_parallel $nthreads
…		…
1732	longer exceeded.	2074	longer exceeded.
1733		2075
1734	In other words, this setting does not enforce a queue limit, but can be	2076	In other words, this setting does not enforce a queue limit, but can be
1735	used to make poll functions block if the limit is exceeded.	2077	used to make poll functions block if the limit is exceeded.
1736		2078
1737	This is a very bad function to use in interactive programs because it	2079	This is a bad function to use in interactive programs because it blocks,
1738	blocks, and a bad way to reduce concurrency because it is inexact: Better	2080	and a bad way to reduce concurrency because it is inexact. If you need to
		2081	issue many requests without being able to call a poll function on demand,
1739	use an C<aio_group> together with a feed callback.	2082	it is better to use an C<aio_group> together with a feed callback.
1740		2083
1741	It's main use is in scripts without an event loop - when you want to stat	2084	Its main use is in scripts without an event loop - when you want to stat a
1742	a lot of files, you can write somehting like this:	2085	lot of files, you can write something like this:
1743		2086
1744	IO::AIO::max_outstanding 32;	2087	IO::AIO::max_outstanding 32;
1745		2088
1746	for my $path (...) {	2089	for my $path (...) {
1747	aio_stat $path , ...;	2090	aio_stat $path , ...;
1748	IO::AIO::poll_cb;	2091	IO::AIO::poll_cb;
1749	}	2092	}
1750		2093
1751	IO::AIO::flush;	2094	IO::AIO::flush;
1752		2095
1753	The call to C<poll_cb> inside the loop will normally return instantly, but	2096	The call to C<poll_cb> inside the loop will normally return instantly,
1754	as soon as more thna C<32> reqeusts are in-flight, it will block until	2097	allowing the loop to progress, but as soon as more than C<32> requests
1755	some requests have been handled. This keeps the loop from pushing a large	2098	are in-flight, it will block until some requests have been handled. This
1756	number of C<aio_stat> requests onto the queue.	2099	keeps the loop from pushing a large number of C<aio_stat> requests onto
		2100	the queue (which, with many paths to stat, can use up a lot of memory).
1757		2101
1758	The default value for C<max_outstanding> is very large, so there is no	2102	The default value for C<max_outstanding> is very large, so there is no
1759	practical limit on the number of outstanding requests.	2103	practical limit on the number of outstanding requests.
1760		2104
1761	=back	2105	=back
1762		2106
		2107
1763	=head3 STATISTICAL INFORMATION	2108	=head3 STATISTICAL INFORMATION
1764		2109
1765	=over	2110	=over
1766		2111
1767	=item IO::AIO::nreqs	2112	=item IO::AIO::nreqs
…		…
1784	Returns the number of requests currently in the pending state (executed,	2129	Returns the number of requests currently in the pending state (executed,
1785	but not yet processed by poll_cb).	2130	but not yet processed by poll_cb).
1786		2131
1787	=back	2132	=back
1788		2133
		2134
		2135	=head3 SUBSECOND STAT TIME ACCESS
		2136
		2137	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2138	generally find access/modification and change times with subsecond time
		2139	accuracy of the system supports it, but perl's built-in functions only
		2140	return the integer part.
		2141
		2142	The following functions return the timestamps of the most recent
		2143	stat with subsecond precision on most systems and work both after
		2144	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2145	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2146	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2147
		2148	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2149	full resolution without rounding and work with standard perl C<stat>,
		2150	alleviating the need to call the special C<Time::HiRes> functions, which
		2151	do not act like their perl counterparts.
		2152
		2153	On operating systems or file systems where subsecond time resolution is
		2154	not supported or could not be detected, a fractional part of C<0> is
		2155	returned, so it is always safe to call these functions.
		2156
		2157	=over 4
		2158
		2159	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		2160
		2161	Return the access, modication, change or birth time, respectively,
		2162	including fractional part. Due to the limited precision of floating point,
		2163	the accuracy on most platforms is only a bit better than milliseconds
		2164	for times around now - see the I<nsec> function family, below, for full
		2165	accuracy.
		2166
		2167	File birth time is only available when the OS and perl support it (on
		2168	FreeBSD and NetBSD at the time of this writing, although support is
		2169	adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
		2170	it). On systems where it isn't available, C<0> is currently returned, but
		2171	this might change to C<undef> in a future version.
		2172
		2173	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		2174
		2175	Returns access, modification, change and birth time all in one go, and
		2176	maybe more times in the future version.
		2177
		2178	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		2179
		2180	Return the fractional access, modifcation, change or birth time, in nanoseconds,
		2181	as an integer in the range C<0> to C<999999999>.
		2182
		2183	Note that no accessors are provided for access, modification and
		2184	change times - you need to get those from C<stat _> if required (C<int
		2185	IO::AIO::st_atime> and so on will I<not> generally give you the correct
		2186	value).
		2187
		2188	=item $seconds = IO::AIO::st_btimesec
		2189
		2190	The (integral) seconds part of the file birth time, if available.
		2191
		2192	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		2193
		2194	Like the functions above, but returns all four times in one go (and maybe
		2195	more in future versions).
		2196
		2197	=item $counter = IO::AIO::st_gen
		2198
		2199	Returns the generation counter (in practice this is just a random number)
		2200	of the file. This is only available on platforms which have this member in
		2201	their C<struct stat> (most BSDs at the time of this writing) and generally
		2202	only to the root usert. If unsupported, C<0> is returned, but this might
		2203	change to C<undef> in a future version.
		2204
		2205	=back
		2206
		2207	Example: print the high resolution modification time of F</etc>, using
		2208	C<stat>, and C<IO::AIO::aio_stat>.
		2209
		2210	if (stat "/etc") {
		2211	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2212	}
		2213
		2214	IO::AIO::aio_stat "/etc", sub {
		2215	$_[0]
		2216	and return;
		2217
		2218	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2219	};
		2220
		2221	IO::AIO::flush;
		2222
		2223	Output of the awbove on my system, showing reduced and full accuracy:
		2224
		2225	stat(/etc) mtime: 1534043702.020808
		2226	aio_stat(/etc) mtime: 1534043702.020807792
		2227
		2228
1789	=head3 MISCELLANEOUS FUNCTIONS	2229	=head3 MISCELLANEOUS FUNCTIONS
1790		2230
1791	IO::AIO implements some functions that might be useful, but are not	2231	IO::AIO implements some functions that are useful when you want to use
1792	asynchronous.	2232	some "Advanced I/O" function not available to in Perl, without going the
		2233	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2234	counterpart.
1793		2235
1794	=over 4	2236	=over 4
		2237
		2238	=item $retval = IO::AIO::fexecve $fh, $argv, $envp
		2239
		2240	A more-or-less direct equivalent to the POSIX C<fexecve> functions, which
		2241	allows you to specify the program to be executed via a file descriptor (or
		2242	handle). Returns C<-1> and sets errno to C<ENOSYS> if not available.
		2243
		2244	=item $numfd = IO::AIO::get_fdlimit
		2245
		2246	Tries to find the current file descriptor limit and returns it, or
		2247	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2248	the highest valid file descriptor number.
		2249
		2250	=item IO::AIO::min_fdlimit [$numfd]
		2251
		2252	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2253	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2254	is missing, it will try to set a very high limit, although this is not
		2255	recommended when you know the actual minimum that you require.
		2256
		2257	If the limit cannot be raised enough, the function makes a best-effort
		2258	attempt to increase the limit as much as possible, using various
		2259	tricks, while still failing. You can query the resulting limit using
		2260	C<IO::AIO::get_fdlimit>.
		2261
		2262	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2263	true.
1795		2264
1796	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2265	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1797		2266
1798	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2267	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1799	but is blocking (this makes most sense if you know the input data is	2268	but is blocking (this makes most sense if you know the input data is
…		…
1816	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2285	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1817		2286
1818	Simply calls the C<posix_madvise> function (see its	2287	Simply calls the C<posix_madvise> function (see its
1819	manpage for details). The following advice constants are	2288	manpage for details). The following advice constants are
1820	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2289	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1821	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2290	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2291	C<IO::AIO::MADV_DONTNEED>.
		2292
		2293	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2294	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2295	will be reduced to fit into the C<$scalar>.
1822		2296
1823	On systems that do not implement C<posix_madvise>, this function returns	2297	On systems that do not implement C<posix_madvise>, this function returns
1824	ENOSYS, otherwise the return value of C<posix_madvise>.	2298	ENOSYS, otherwise the return value of C<posix_madvise>.
1825		2299
1826	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2300	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
…		…
1828	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2302	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1829	$scalar (see its manpage for details). The following protect	2303	$scalar (see its manpage for details). The following protect
1830	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2304	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1831	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2305	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1832		2306
		2307	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2308	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2309	will be reduced to fit into the C<$scalar>.
		2310
1833	On systems that do not implement C<mprotect>, this function returns	2311	On systems that do not implement C<mprotect>, this function returns
1834	ENOSYS, otherwise the return value of C<mprotect>.	2312	ENOSYS, otherwise the return value of C<mprotect>.
1835		2313
1836	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2314	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1837		2315
1838	Memory-maps a file (or anonymous memory range) and attaches it to the	2316	Memory-maps a file (or anonymous memory range) and attaches it to the
1839	given C<$scalar>, which will act like a string scalar.	2317	given C<$scalar>, which will act like a string scalar. Returns true on
		2318	success, and false otherwise.
1840		2319
		2320	The scalar must exist, but its contents do not matter - this means you
		2321	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2322	the scalar first.
		2323
1841	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2324	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1842	change the string length, and most read-only operations such as copying it	2325	which don't change the string length, and most read-only operations such
1843	or searching it with regexes and so on.	2326	as copying it or searching it with regexes and so on.
1844		2327
1845	Anything else is unsafe and will, at best, result in memory leaks.	2328	Anything else is unsafe and will, at best, result in memory leaks.
1846		2329
1847	The memory map associated with the C<$scalar> is automatically removed	2330	The memory map associated with the C<$scalar> is automatically removed
1848	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2331	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1849	C<IO::AIO::munmap> functions are called.	2332	or C<IO::AIO::munmap> functions are called on it.
1850		2333
1851	This calls the C<mmap>(2) function internally. See your system's manual	2334	This calls the C<mmap>(2) function internally. See your system's manual
1852	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2335	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1853		2336
1854	The C<$length> must be larger than zero and smaller than the actual	2337	The C<$length> must be larger than zero and smaller than the actual
1855	filesize.	2338	filesize.
1856		2339
1857	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2340	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1858	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2341	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1859		2342
1860	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2343	C<$flags> can be a combination of
1861	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2344	C<IO::AIO::MAP_SHARED> or
1862	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2345	C<IO::AIO::MAP_PRIVATE>,
		2346	or a number of system-specific flags (when not available, the are C<0>):
1863	(which is set to C<MAP_ANON> if your system only provides this	2347	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1864	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2348	C<IO::AIO::MAP_LOCKED>,
1865	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2349	C<IO::AIO::MAP_NORESERVE>,
		2350	C<IO::AIO::MAP_POPULATE>,
1866	C<IO::AIO::MAP_NONBLOCK>	2351	C<IO::AIO::MAP_NONBLOCK>,
		2352	C<IO::AIO::MAP_FIXED>,
		2353	C<IO::AIO::MAP_GROWSDOWN>,
		2354	C<IO::AIO::MAP_32BIT>,
		2355	C<IO::AIO::MAP_HUGETLB>,
		2356	C<IO::AIO::MAP_STACK>,
		2357	C<IO::AIO::MAP_FIXED_NOREPLACE>,
		2358	C<IO::AIO::MAP_SHARED_VALIDATE>,
		2359	C<IO::AIO::MAP_SYNC> or
		2360	C<IO::AIO::MAP_UNINITIALIZED>.
1867		2361
1868	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2362	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1869		2363
1870	C<$offset> is the offset from the start of the file - it generally must be	2364	C<$offset> is the offset from the start of the file - it generally must be
1871	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2365	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1885		2379
1886	=item IO::AIO::munmap $scalar	2380	=item IO::AIO::munmap $scalar
1887		2381
1888	Removes a previous mmap and undefines the C<$scalar>.	2382	Removes a previous mmap and undefines the C<$scalar>.
1889		2383
		2384	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2385
		2386	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2387	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2388	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2389
		2390	Returns true if successful, and false otherwise. If the underlying mmapped
		2391	region has changed address, then the true value has the numerical value
		2392	C<1>, otherwise it has the numerical value C<0>:
		2393
		2394	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2395	or die "mremap: $!";
		2396
		2397	if ($success*1) {
		2398	warn "scalar has chanegd address in memory\n";
		2399	}
		2400
		2401	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2402	implemented, but not supported and might go away in a future version.
		2403
		2404	On systems where this call is not supported or is not emulated, this call
		2405	returns falls and sets C<$!> to C<ENOSYS>.
		2406
		2407	=item IO::AIO::mlockall $flags
		2408
		2409	Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
		2410	but is blocking.
		2411
1890	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef	2412	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1891		2413
1892	Calls the C<munlock> function, undoing the effects of a previous	2414	Calls the C<munlock> function, undoing the effects of a previous
1893	C<aio_mlock> call (see its description for details).	2415	C<aio_mlock> call (see its description for details).
1894		2416
…		…
1896		2418
1897	Calls the C<munlockall> function.	2419	Calls the C<munlockall> function.
1898		2420
1899	On systems that do not implement C<munlockall>, this function returns	2421	On systems that do not implement C<munlockall>, this function returns
1900	ENOSYS, otherwise the return value of C<munlockall>.	2422	ENOSYS, otherwise the return value of C<munlockall>.
		2423
		2424	=item $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		2425
		2426	Uses the GNU/Linux C<accept4(2)> syscall, if available, to accept a socket
		2427	and return the new file handle on success, or sets C<$!> and returns
		2428	C<undef> on error.
		2429
		2430	The remote name of the new socket will be stored in C<$sockaddr>, which
		2431	will be extended to allow for at least C<$sockaddr_maxlen> octets. If the
		2432	socket name does not fit into C<$sockaddr_maxlen> octets, this is signaled
		2433	by returning a longer string in C<$sockaddr>, which might or might not be
		2434	truncated.
		2435
		2436	To accept name-less sockets, use C<undef> for C<$sockaddr> and C<0> for
		2437	C<$sockaddr_maxlen>.
		2438
		2439	The main reasons to use this syscall rather than portable C<accept(2)>
		2440	are that you can specify C<SOCK_NONBLOCK> and/or C<SOCK_CLOEXEC>
		2441	flags and you can accept name-less sockets by specifying C<0> for
		2442	C<$sockaddr_maxlen>, which is sadly not possible with perl's interface to
		2443	C<accept>.
		2444
		2445	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2446
		2447	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2448	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2449	should be the file offset.
		2450
		2451	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2452	silently corrupt the data in this case.
		2453
		2454	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2455	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2456	C<IO::AIO::SPLICE_F_GIFT>.
		2457
		2458	See the C<splice(2)> manpage for details.
		2459
		2460	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2461
		2462	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2463	description for C<IO::AIO::splice> above for details.
		2464
		2465	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2466
		2467	Attempts to query or change the pipe buffer size. Obviously works only
		2468	on pipes, and currently works only on GNU/Linux systems, and fails with
		2469	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2470	size on other systems, drop me a note.
		2471
		2472	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2473
		2474	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2475	C<$flags> is missing or C<0>, then this should be the same as a call to
		2476	perl's built-in C<pipe> function and create a new pipe, and works on
		2477	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2478	(..., 4096, O_BINARY)>.
		2479
		2480	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2481	the given flags (Linux 2.6.27, glibc 2.9).
		2482
		2483	On success, the read and write file handles are returned.
		2484
		2485	On error, nothing will be returned. If the pipe2 syscall is missing and
		2486	C<$flags> is non-zero, fails with C<ENOSYS>.
		2487
		2488	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2489	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2490	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2491
		2492	Example: create a pipe race-free w.r.t. threads and fork:
		2493
		2494	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2495	or die "pipe2: $!\n";
		2496
		2497	=item $fh = IO::AIO::memfd_create $pathname[, $flags]
		2498
		2499	This is a direct interface to the Linux L<memfd_create(2)> system
		2500	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2501	should be C<IO::AIO::MFD_CLOEXEC>.
		2502
		2503	On success, the new memfd filehandle is returned, otherwise returns
		2504	C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
		2505
		2506	Please refer to L<memfd_create(2)> for more info on this call.
		2507
		2508	The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
		2509	C<IO::AIO::MFD_ALLOW_SEALING>, C<IO::AIO::MFD_HUGETLB>,
		2510	C<IO::AIO::MFD_HUGETLB_2MB> and C<IO::AIO::MFD_HUGETLB_1GB>.
		2511
		2512	Example: create a new memfd.
		2513
		2514	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2515	or die "memfd_create: $!\n";
		2516
		2517	=item $fh = IO::AIO::pidfd_open $pid[, $flags]
		2518
		2519	This is an interface to the Linux L<pidfd_open(2)> system call. The
		2520	default for C<$flags> is C<0>.
		2521
		2522	On success, a new pidfd filehandle is returned (that is already set to
		2523	close-on-exec), otherwise returns C<undef>. If the syscall is missing,
		2524	fails with C<ENOSYS>.
		2525
		2526	Example: open pid 6341 as pidfd.
		2527
		2528	my $fh = IO::AIO::pidfd_open 6341
		2529	or die "pidfd_open: $!\n";
		2530
		2531	=item $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		2532
		2533	This is an interface to the Linux L<pidfd_send_signal> system call. The
		2534	default for C<$siginfo> is C<undef> and the default for C<$flags> is C<0>.
		2535
		2536	Returns the system call status. If the syscall is missing, fails with
		2537	C<ENOSYS>.
		2538
		2539	When specified, C<$siginfo> must be a reference to a hash with one or more
		2540	of the following members:
		2541
		2542	=over
		2543
		2544	=item code - the C<si_code> member
		2545
		2546	=item pid - the C<si_pid> member
		2547
		2548	=item uid - the C<si_uid> member
		2549
		2550	=item value_int - the C<si_value.sival_int> member
		2551
		2552	=item value_ptr - the C<si_value.sival_ptr> member, specified as an integer
		2553
		2554	=back
		2555
		2556	Example: send a SIGKILL to the specified process.
		2557
		2558	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
		2559	and die "pidfd_send_signal: $!\n";
		2560
		2561	Example: send a SIGKILL to the specified process with extra data.
		2562
		2563	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
		2564	and die "pidfd_send_signal: $!\n";
		2565
		2566	=item $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		2567
		2568	This is an interface to the Linux L<pidfd_getfd> system call. The default
		2569	for C<$flags> is C<0>.
		2570
		2571	On success, returns a dup'ed copy of the target file descriptor (specified
		2572	as an integer) returned (that is already set to close-on-exec), otherwise
		2573	returns C<undef>. If the syscall is missing, fails with C<ENOSYS>.
		2574
		2575	Example: get a copy of standard error of another process and print soemthing to it.
		2576
		2577	my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
		2578	or die "pidfd_getfd: $!\n";
		2579	print $errfh "stderr\n";
		2580
		2581	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2582
		2583	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2584	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2585
		2586	On success, the new eventfd filehandle is returned, otherwise returns
		2587	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2588
		2589	Please refer to L<eventfd(2)> for more info on this call.
		2590
		2591	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2592	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2593
		2594	Example: create a new eventfd filehandle:
		2595
		2596	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2597	or die "eventfd: $!\n";
		2598
		2599	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2600
		2601	This is a direct interface to the Linux L<timerfd_create(2)> system
		2602	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2603	should be C<IO::AIO::TFD_CLOEXEC>.
		2604
		2605	On success, the new timerfd filehandle is returned, otherwise returns
		2606	C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
		2607
		2608	Please refer to L<timerfd_create(2)> for more info on this call.
		2609
		2610	The following C<$clockid> values are
		2611	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2612	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2613	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2614	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2615
		2616	The following C<$flags> values are available (Linux
		2617	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2618
		2619	Example: create a new timerfd and set it to one-second repeated alarms,
		2620	then wait for two alarms:
		2621
		2622	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2623	or die "timerfd_create: $!\n";
		2624
		2625	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2626	or die "timerfd_settime: $!\n";
		2627
		2628	for (1..2) {
		2629	8 == sysread $fh, my $buf, 8
		2630	or die "timerfd read failure\n";
		2631
		2632	printf "number of expirations (likely 1): %d\n",
		2633	unpack "Q", $buf;
		2634	}
		2635
		2636	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2637
		2638	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2639	call. Please refer to its manpage for more info on this call.
		2640
		2641	The new itimerspec is specified using two (possibly fractional) second
		2642	values, C<$new_interval> and C<$new_value>).
		2643
		2644	On success, the current interval and value are returned (as per
		2645	C<timerfd_gettime>). On failure, the empty list is returned.
		2646
		2647	The following C<$flags> values are
		2648	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2649	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2650
		2651	See C<IO::AIO::timerfd_create> for a full example.
		2652
		2653	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2654
		2655	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2656	call. Please refer to its manpage for more info on this call.
		2657
		2658	On success, returns the current values of interval and value for the given
		2659	timerfd (as potentially fractional second values). On failure, the empty
		2660	list is returned.
1901		2661
1902	=back	2662	=back
1903		2663
1904	=cut	2664	=cut
1905		2665
…		…
1971	the process will result in undefined behaviour. Calling it at any time	2731	the process will result in undefined behaviour. Calling it at any time
1972	will also result in any undefined (by POSIX) behaviour.	2732	will also result in any undefined (by POSIX) behaviour.
1973		2733
1974	=back	2734	=back
1975		2735
		2736	=head2 LINUX-SPECIFIC CALLS
		2737
		2738	When a call is documented as "linux-specific" then this means it
		2739	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2740	availability and compatibility of such calls regardless of the platform
		2741	it is compiled on, so platforms such as FreeBSD which often implement
		2742	these calls will work. When in doubt, call them and see if they fail wth
		2743	C<ENOSYS>.
		2744
1976	=head2 MEMORY USAGE	2745	=head2 MEMORY USAGE
1977		2746
1978	Per-request usage:	2747	Per-request usage:
1979		2748
1980	Each aio request uses - depending on your architecture - around 100-200	2749	Each aio request uses - depending on your architecture - around 100-200
…		…
1992	temporary buffers, and each thread requires a stack and other data	2761	temporary buffers, and each thread requires a stack and other data
1993	structures (usually around 16k-128k, depending on the OS).	2762	structures (usually around 16k-128k, depending on the OS).
1994		2763
1995	=head1 KNOWN BUGS	2764	=head1 KNOWN BUGS
1996		2765
1997	Known bugs will be fixed in the next release.	2766	Known bugs will be fixed in the next release :)
		2767
		2768	=head1 KNOWN ISSUES
		2769
		2770	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2771	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2772	non-created hash slots or other scalars I didn't think of. It's best to
		2773	avoid such and either use scalar variables or making sure that the scalar
		2774	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2775
		2776	I am not sure anything can be done about this, so this is considered a
		2777	known issue, rather than a bug.
1998		2778
1999	=head1 SEE ALSO	2779	=head1 SEE ALSO
2000		2780
2001	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2781	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
2002	more natural syntax.	2782	more natural syntax and L<IO::FDPass> for file descriptor passing.
2003		2783
2004	=head1 AUTHOR	2784	=head1 AUTHOR
2005		2785
2006	Marc Lehmann <schmorp@schmorp.de>	2786	Marc Lehmann <schmorp@schmorp.de>
2007	http://home.schmorp.de/	2787	http://home.schmorp.de/

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