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Revision 1.209 by root, Tue Sep 27 00:41:51 2011 UTC vs.
Revision 1.306 by root, Wed Oct 16 09:11:35 2019 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	IO::AIO - Asynchronous Input/Output	3	IO::AIO - Asynchronous/Advanced Input/Output
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
…		…
58	not well-supported or restricted (GNU/Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
59	files currently, for example), and they would only support aio_read and	59	files currently, for example), and they would only support aio_read and
60	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
61	using threads anyway.	61	using threads anyway.
62		62
		63	In addition to asynchronous I/O, this module also exports some rather
		64	arcane interfaces, such as C<madvise> or linux's C<splice> system call,
		65	which is why the C<A> in C<AIO> can also mean I<advanced>.
		66
63	Although the module will work in the presence of other (Perl-) threads,	67	Although the module will work in the presence of other (Perl-) threads,
64	it is currently not reentrant in any way, so use appropriate locking	68	it is currently not reentrant in any way, so use appropriate locking
65	yourself, always call C<poll_cb> from within the same thread, or never	69	yourself, always call C<poll_cb> from within the same thread, or never
66	call C<poll_cb> (or other C<aio_> functions) recursively.	70	call C<poll_cb> (or other C<aio_> functions) recursively.
67		71
68	=head2 EXAMPLE	72	=head2 EXAMPLE
69		73
70	This is a simple example that uses the EV module and loads	74	This is a simple example that uses the EV module and loads
71	F</etc/passwd> asynchronously:	75	F</etc/passwd> asynchronously:
72		76
73	use Fcntl;
74	use EV;	77	use EV;
75	use IO::AIO;	78	use IO::AIO;
76		79
77	# register the IO::AIO callback with EV	80	# register the IO::AIO callback with EV
78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	81	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
…		…
95		98
96	# file contents now in $contents	99	# file contents now in $contents
97	print $contents;	100	print $contents;
98		101
99	# exit event loop and program	102	# exit event loop and program
100	EV::unloop;	103	EV::break;
101	};	104	};
102	};	105	};
103		106
104	# possibly queue up other requests, or open GUI windows,	107	# possibly queue up other requests, or open GUI windows,
105	# check for sockets etc. etc.	108	# check for sockets etc. etc.
106		109
107	# process events as long as there are some:	110	# process events as long as there are some:
108	EV::loop;	111	EV::run;
109		112
110	=head1 REQUEST ANATOMY AND LIFETIME	113	=head1 REQUEST ANATOMY AND LIFETIME
111		114
112	Every C<aio_*> function creates a request. which is a C data structure not	115	Every C<aio_*> function creates a request. which is a C data structure not
113	directly visible to Perl.	116	directly visible to Perl.
…		…
168	use common::sense;	171	use common::sense;
169		172
170	use base 'Exporter';	173	use base 'Exporter';
171		174
172	BEGIN {	175	BEGIN {
173	our $VERSION = '4.0';	176	our $VERSION = 4.73;
174		177
175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	178	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx	179	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate	181	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
179	aio_pathsync aio_readahead	182	aio_pathsync aio_readahead aio_fiemap aio_allocate
180	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
181	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	184	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
182	aio_chmod aio_utime aio_truncate	185	aio_chmod aio_utime aio_truncate
183	aio_msync aio_mtouch aio_mlock aio_mlockall	186	aio_msync aio_mtouch aio_mlock aio_mlockall
184	aio_statvfs	187	aio_statvfs
		188	aio_slurp
185	aio_wd);	189	aio_wd);
186		190
187	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	191	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
188	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	192	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
189	min_parallel max_parallel max_idle idle_timeout	193	min_parallel max_parallel max_idle idle_timeout
190	nreqs nready npending nthreads	194	nreqs nready npending nthreads
191	max_poll_time max_poll_reqs	195	max_poll_time max_poll_reqs
192	sendfile fadvise madvise	196	sendfile fadvise madvise
193	mmap munmap munlock munlockall);	197	mmap munmap mremap munlock munlockall);
194		198
195	push @AIO_REQ, qw(aio_busy); # not exported	199	push @AIO_REQ, qw(aio_busy); # not exported
196		200
197	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	201	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
198		202
…		…
202		206
203	=head1 FUNCTIONS	207	=head1 FUNCTIONS
204		208
205	=head2 QUICK OVERVIEW	209	=head2 QUICK OVERVIEW
206		210
207	This section simply lists the prototypes of the most important functions	211	This section simply lists the prototypes most of the functions for
208	for quick reference. See the following sections for function-by-function	212	quick reference. See the following sections for function-by-function
209	documentation.	213	documentation.
210		214
211	aio_wd $pathname, $callback->($wd)	215	aio_wd $pathname, $callback->($wd)
212	aio_open $pathname, $flags, $mode, $callback->($fh)	216	aio_open $pathname, $flags, $mode, $callback->($fh)
213	aio_close $fh, $callback->($status)	217	aio_close $fh, $callback->($status)
		218	aio_seek $fh,$offset,$whence, $callback->($offs)
214	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	219	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
215	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	220	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
216	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	221	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
217	aio_readahead $fh,$offset,$length, $callback->($retval)	222	aio_readahead $fh,$offset,$length, $callback->($retval)
218	aio_stat $fh_or_path, $callback->($status)	223	aio_stat $fh_or_path, $callback->($status)
219	aio_lstat $fh, $callback->($status)	224	aio_lstat $fh, $callback->($status)
220	aio_statvfs $fh_or_path, $callback->($statvfs)	225	aio_statvfs $fh_or_path, $callback->($statvfs)
221	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	226	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
222	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	227	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		228	aio_chmod $fh_or_path, $mode, $callback->($status)
223	aio_truncate $fh_or_path, $offset, $callback->($status)	229	aio_truncate $fh_or_path, $offset, $callback->($status)
224	aio_chmod $fh_or_path, $mode, $callback->($status)	230	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		231	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
225	aio_unlink $pathname, $callback->($status)	232	aio_unlink $pathname, $callback->($status)
226	aio_mknod $pathname, $mode, $dev, $callback->($status)	233	aio_mknod $pathname, $mode, $dev, $callback->($status)
227	aio_link $srcpath, $dstpath, $callback->($status)	234	aio_link $srcpath, $dstpath, $callback->($status)
228	aio_symlink $srcpath, $dstpath, $callback->($status)	235	aio_symlink $srcpath, $dstpath, $callback->($status)
229	aio_readlink $pathname, $callback->($link)	236	aio_readlink $pathname, $callback->($link)
230	aio_realpath $pathname, $callback->($link)	237	aio_realpath $pathname, $callback->($path)
231	aio_rename $srcpath, $dstpath, $callback->($status)	238	aio_rename $srcpath, $dstpath, $callback->($status)
		239	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
232	aio_mkdir $pathname, $mode, $callback->($status)	240	aio_mkdir $pathname, $mode, $callback->($status)
233	aio_rmdir $pathname, $callback->($status)	241	aio_rmdir $pathname, $callback->($status)
234	aio_readdir $pathname, $callback->($entries)	242	aio_readdir $pathname, $callback->($entries)
235	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	243	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
236	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	244	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
237	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	245	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		246	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
238	aio_load $pathname, $data, $callback->($status)	247	aio_load $pathname, $data, $callback->($status)
239	aio_copy $srcpath, $dstpath, $callback->($status)	248	aio_copy $srcpath, $dstpath, $callback->($status)
240	aio_move $srcpath, $dstpath, $callback->($status)	249	aio_move $srcpath, $dstpath, $callback->($status)
241	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
242	aio_rmtree $pathname, $callback->($status)	250	aio_rmtree $pathname, $callback->($status)
		251	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		252	aio_ioctl $fh, $request, $buf, $callback->($status)
243	aio_sync $callback->($status)	253	aio_sync $callback->($status)
244	aio_syncfs $fh, $callback->($status)	254	aio_syncfs $fh, $callback->($status)
245	aio_fsync $fh, $callback->($status)	255	aio_fsync $fh, $callback->($status)
246	aio_fdatasync $fh, $callback->($status)	256	aio_fdatasync $fh, $callback->($status)
247	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	257	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
248	aio_pathsync $pathname, $callback->($status)	258	aio_pathsync $pathname, $callback->($status)
249	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	259	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
250	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	260	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
251	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	261	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
252	aio_mlockall $flags, $callback->($status)	262	aio_mlockall $flags, $callback->($status)
253	aio_group $callback->(...)	263	aio_group $callback->(...)
254	aio_nop $callback->()	264	aio_nop $callback->()
…		…
268	IO::AIO::idle_timeout $seconds	278	IO::AIO::idle_timeout $seconds
269	IO::AIO::max_outstanding $maxreqs	279	IO::AIO::max_outstanding $maxreqs
270	IO::AIO::nreqs	280	IO::AIO::nreqs
271	IO::AIO::nready	281	IO::AIO::nready
272	IO::AIO::npending	282	IO::AIO::npending
		283	IO::AIO::reinit
		284
		285	$nfd = IO::AIO::get_fdlimit [EXPERIMENTAL]
		286	IO::AIO::min_fdlimit $nfd [EXPERIMENTAL]
273		287
274	IO::AIO::sendfile $ofh, $ifh, $offset, $count	288	IO::AIO::sendfile $ofh, $ifh, $offset, $count
275	IO::AIO::fadvise $fh, $offset, $len, $advice	289	IO::AIO::fadvise $fh, $offset, $len, $advice
		290
		291	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		292	IO::AIO::munmap $scalar
		293	IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
276	IO::AIO::madvise $scalar, $offset, $length, $advice	294	IO::AIO::madvise $scalar, $offset, $length, $advice
277	IO::AIO::mprotect $scalar, $offset, $length, $protect	295	IO::AIO::mprotect $scalar, $offset, $length, $protect
278	IO::AIO::munlock $scalar, $offset = 0, $length = undef	296	IO::AIO::munlock $scalar, $offset = 0, $length = undef
279	IO::AIO::munlockall	297	IO::AIO::munlockall
280		298
281	=head2 AIO REQUEST FUNCTIONS	299	# stat extensions
		300	$counter = IO::AIO::st_gen
		301	$seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		302	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		303	$nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		304	$seconds = IO::AIO::st_btimesec
		305	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		306
		307	# very much unportable syscalls
		308	IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
		309	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		310	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		311	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		312	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		313	$fh = IO::AIO::memfd_create $pathname[, $flags]
		314	$fh = IO::AIO::eventfd [$initval, [$flags]]
		315	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		316	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		317	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		318
		319	=head2 API NOTES
282		320
283	All the C<aio_*> calls are more or less thin wrappers around the syscall	321	All the C<aio_*> calls are more or less thin wrappers around the syscall
284	with the same name (sans C<aio_>). The arguments are similar or identical,	322	with the same name (sans C<aio_>). The arguments are similar or identical,
285	and they all accept an additional (and optional) C<$callback> argument	323	and they all accept an additional (and optional) C<$callback> argument
286	which must be a code reference. This code reference will get called with	324	which must be a code reference. This code reference will be called after
287	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	325	the syscall has been executed in an asynchronous fashion. The results
288	perl, which usually delivers "false") as its sole argument after the given	326	of the request will be passed as arguments to the callback (and, if an
289	syscall has been executed asynchronously.	327	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		328	most syscalls return C<-1> on error, unlike perl, which usually delivers
		329	"false").
		330
		331	Some requests (such as C<aio_readdir>) pass the actual results and
		332	communicate failures by passing C<undef>.
290		333
291	All functions expecting a filehandle keep a copy of the filehandle	334	All functions expecting a filehandle keep a copy of the filehandle
292	internally until the request has finished.	335	internally until the request has finished.
293		336
294	All functions return request objects of type L<IO::AIO::REQ> that allow	337	All functions return request objects of type L<IO::AIO::REQ> that allow
295	further manipulation of those requests while they are in-flight.	338	further manipulation of those requests while they are in-flight.
296		339
297	The pathnames you pass to these routines I<should> be absolute. The	340	The pathnames you pass to these routines I<should> be absolute. The
298	reason for this is that at the time the request is being executed, the	341	reason for this is that at the time the request is being executed, the
299	current working directory could have changed. Alternatively, you can make	342	current working directory could have changed. Alternatively, you can
300	sure that you never change the current working directory anywhere in	343	make sure that you never change the current working directory anywhere
301	the program and then use relative paths. Lastly, you can take advantage	344	in the program and then use relative paths. You can also take advantage
302	of IO::AIOs working directory abstraction - see the description of the	345	of IO::AIOs working directory abstraction, that lets you specify paths
		346	relative to some previously-opened "working directory object" - see the
303	C<IO::AIO::WD> class later in this document.	347	description of the C<IO::AIO::WD> class later in this document.
304		348
305	To encode pathnames as octets, either make sure you either: a) always pass	349	To encode pathnames as octets, either make sure you either: a) always pass
306	in filenames you got from outside (command line, readdir etc.) without	350	in filenames you got from outside (command line, readdir etc.) without
307	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	351	tinkering, b) are in your native filesystem encoding, c) use the Encode
308	your pathnames to the locale (or other) encoding in effect in the user	352	module and encode your pathnames to the locale (or other) encoding in
309	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	353	effect in the user environment, d) use Glib::filename_from_unicode on
310	use something else to ensure your scalar has the correct contents.	354	unicode filenames or e) use something else to ensure your scalar has the
		355	correct contents.
311		356
312	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	357	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
313	handles correctly whether it is set or not.	358	handles correctly whether it is set or not.
		359
		360	=head2 AIO REQUEST FUNCTIONS
314		361
315	=over 4	362	=over 4
316		363
317	=item $prev_pri = aioreq_pri [$pri]	364	=item $prev_pri = aioreq_pri [$pri]
318		365
…		…
348		395
349		396
350	=item aio_open $pathname, $flags, $mode, $callback->($fh)	397	=item aio_open $pathname, $flags, $mode, $callback->($fh)
351		398
352	Asynchronously open or create a file and call the callback with a newly	399	Asynchronously open or create a file and call the callback with a newly
353	created filehandle for the file.	400	created filehandle for the file (or C<undef> in case of an error).
354		401
355	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	402	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
356	for an explanation.	403	for an explanation.
357		404
358	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	405	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
381	following POSIX and non-POSIX constants are available (missing ones on	428	following POSIX and non-POSIX constants are available (missing ones on
382	your system are, as usual, C<0>):	429	your system are, as usual, C<0>):
383		430
384	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,	431	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
385	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,	432	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
386	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.	433	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
387		434
388		435
389	=item aio_close $fh, $callback->($status)	436	=item aio_close $fh, $callback->($status)
390		437
391	Asynchronously close a file and call the callback with the result	438	Asynchronously close a file and call the callback with the result
…		…
401	Or in other words: the file descriptor will be closed, but it will not be	448	Or in other words: the file descriptor will be closed, but it will not be
402	free for reuse until the perl filehandle is closed.	449	free for reuse until the perl filehandle is closed.
403		450
404	=cut	451	=cut
405		452
		453	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		454
		455	Seeks the filehandle to the new C<$offset>, similarly to perl's
		456	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		457	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		458	C<IO::AIO::SEEK_END>).
		459
		460	The resulting absolute offset will be passed to the callback, or C<-1> in
		461	case of an error.
		462
		463	In theory, the C<$whence> constants could be different than the
		464	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		465	so don't panic.
		466
		467	As a GNU/Linux (and maybe Solaris) extension, also the constants
		468	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		469	could be found. No guarantees about suitability for use in C<aio_seek> or
		470	Perl's C<sysseek> can be made though, although I would naively assume they
		471	"just work".
		472
406	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	473	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
407		474
408	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	475	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
409		476
410	Reads or writes C<$length> bytes from or to the specified C<$fh> and	477	Reads or writes C<$length> bytes from or to the specified C<$fh> and
411	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	478	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
412	and calls the callback without the actual number of bytes read (or -1 on	479	calls the callback with the actual number of bytes transferred (or -1 on
413	error, just like the syscall).	480	error, just like the syscall).
414		481
415	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	482	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
416	offset plus the actual number of bytes read.	483	offset plus the actual number of bytes read.
417		484
…		…
475	As native sendfile syscalls (as practically any non-POSIX interface hacked	542	As native sendfile syscalls (as practically any non-POSIX interface hacked
476	together in a hurry to improve benchmark numbers) tend to be rather buggy	543	together in a hurry to improve benchmark numbers) tend to be rather buggy
477	on many systems, this implementation tries to work around some known bugs	544	on many systems, this implementation tries to work around some known bugs
478	in Linux and FreeBSD kernels (probably others, too), but that might fail,	545	in Linux and FreeBSD kernels (probably others, too), but that might fail,
479	so you really really should check the return value of C<aio_sendfile> -	546	so you really really should check the return value of C<aio_sendfile> -
480	fewre bytes than expected might have been transferred.	547	fewer bytes than expected might have been transferred.
481		548
482		549
483	=item aio_readahead $fh,$offset,$length, $callback->($retval)	550	=item aio_readahead $fh,$offset,$length, $callback->($retval)
484		551
485	C<aio_readahead> populates the page cache with data from a file so that	552	C<aio_readahead> populates the page cache with data from a file so that
…		…
489	whole pages, so that offset is effectively rounded down to a page boundary	556	whole pages, so that offset is effectively rounded down to a page boundary
490	and bytes are read up to the next page boundary greater than or equal to	557	and bytes are read up to the next page boundary greater than or equal to
491	(off-set+length). C<aio_readahead> does not read beyond the end of the	558	(off-set+length). C<aio_readahead> does not read beyond the end of the
492	file. The current file offset of the file is left unchanged.	559	file. The current file offset of the file is left unchanged.
493		560
494	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	561	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
495	emulated by simply reading the data, which would have a similar effect.	562	be emulated by simply reading the data, which would have a similar effect.
496		563
497		564
498	=item aio_stat $fh_or_path, $callback->($status)	565	=item aio_stat $fh_or_path, $callback->($status)
499		566
500	=item aio_lstat $fh, $callback->($status)	567	=item aio_lstat $fh, $callback->($status)
501		568
502	Works like perl's C<stat> or C<lstat> in void context. The callback will	569	Works almost exactly like perl's C<stat> or C<lstat> in void context. The
503	be called after the stat and the results will be available using C<stat _>	570	callback will be called after the stat and the results will be available
504	or C<-s _> etc...	571	using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
		572	and C<-T>).
505		573
506	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,	574	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
507	for an explanation.	575	for an explanation.
508		576
509	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	577	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
…		…
516	behaviour).	584	behaviour).
517		585
518	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,	586	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
519	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,	587	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
520	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.	588	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		589
		590	To access higher resolution stat timestamps, see L<SUBSECOND STAT TIME
		591	ACCESS>.
521		592
522	Example: Print the length of F</etc/passwd>:	593	Example: Print the length of F</etc/passwd>:
523		594
524	aio_stat "/etc/passwd", sub {	595	aio_stat "/etc/passwd", sub {
525	$_[0] and die "stat failed: $!";	596	$_[0] and die "stat failed: $!";
…		…
569	namemax => 255,	640	namemax => 255,
570	frsize => 1024,	641	frsize => 1024,
571	fsid => 1810	642	fsid => 1810
572	}	643	}
573		644
574
575	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	645	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
576		646
577	Works like perl's C<utime> function (including the special case of $atime	647	Works like perl's C<utime> function (including the special case of $atime
578	and $mtime being undef). Fractional times are supported if the underlying	648	and $mtime being undef). Fractional times are supported if the underlying
579	syscalls support them.	649	syscalls support them.
580		650
581	When called with a pathname, uses utimes(2) if available, otherwise	651	When called with a pathname, uses utimensat(2) or utimes(2) if available,
582	utime(2). If called on a file descriptor, uses futimes(2) if available,	652	otherwise utime(2). If called on a file descriptor, uses futimens(2)
583	otherwise returns ENOSYS, so this is not portable.	653	or futimes(2) if available, otherwise returns ENOSYS, so this is not
		654	portable.
584		655
585	Examples:	656	Examples:
586		657
587	# set atime and mtime to current time (basically touch(1)):	658	# set atime and mtime to current time (basically touch(1)):
588	aio_utime "path", undef, undef;	659	aio_utime "path", undef, undef;
…		…
606	=item aio_truncate $fh_or_path, $offset, $callback->($status)	677	=item aio_truncate $fh_or_path, $offset, $callback->($status)
607		678
608	Works like truncate(2) or ftruncate(2).	679	Works like truncate(2) or ftruncate(2).
609		680
610		681
		682	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		683
		684	Allocates or frees disk space according to the C<$mode> argument. See the
		685	linux C<fallocate> documentation for details.
		686
		687	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		688	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		689	to deallocate a file range.
		690
		691	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		692	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		693	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		694	to unshare shared blocks (see your L<fallocate(2)> manpage).
		695
		696	The file system block size used by C<fallocate> is presumably the
		697	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		698	can dictate other limitations.
		699
		700	If C<fallocate> isn't available or cannot be emulated (currently no
		701	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		702
		703
611	=item aio_chmod $fh_or_path, $mode, $callback->($status)	704	=item aio_chmod $fh_or_path, $mode, $callback->($status)
612		705
613	Works like perl's C<chmod> function.	706	Works like perl's C<chmod> function.
614		707
615		708
…		…
652		745
653		746
654	=item aio_realpath $pathname, $callback->($path)	747	=item aio_realpath $pathname, $callback->($path)
655		748
656	Asynchronously make the path absolute and resolve any symlinks in	749	Asynchronously make the path absolute and resolve any symlinks in
657	C<$path>. The resulting path only consists of directories (Same as	750	C<$path>. The resulting path only consists of directories (same as
658	L<Cwd::realpath>).	751	L<Cwd::realpath>).
659		752
660	This request can be used to get the absolute path of the current working	753	This request can be used to get the absolute path of the current working
661	directory by passing it a path of F<.> (a single dot).	754	directory by passing it a path of F<.> (a single dot).
662		755
663		756
664	=item aio_rename $srcpath, $dstpath, $callback->($status)	757	=item aio_rename $srcpath, $dstpath, $callback->($status)
665		758
666	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	759	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
667	rename(2) and call the callback with the result code.	760	rename(2) and call the callback with the result code.
		761
		762	On systems that support the AIO::WD working directory abstraction
		763	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		764	of failing, C<rename> is called on the absolute path of C<$wd>.
		765
		766
		767	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		768
		769	Basically a version of C<aio_rename> with an additional C<$flags>
		770	argument. Calling this with C<$flags=0> is the same as calling
		771	C<aio_rename>.
		772
		773	Non-zero flags are currently only supported on GNU/Linux systems that
		774	support renameat2. Other systems fail with C<ENOSYS> in this case.
		775
		776	The following constants are available (missing ones are, as usual C<0>),
		777	see renameat2(2) for details:
		778
		779	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		780	and C<IO::AIO::RENAME_WHITEOUT>.
668		781
669		782
670	=item aio_mkdir $pathname, $mode, $callback->($status)	783	=item aio_mkdir $pathname, $mode, $callback->($status)
671		784
672	Asynchronously mkdir (create) a directory and call the callback with	785	Asynchronously mkdir (create) a directory and call the callback with
…		…
677	=item aio_rmdir $pathname, $callback->($status)	790	=item aio_rmdir $pathname, $callback->($status)
678		791
679	Asynchronously rmdir (delete) a directory and call the callback with the	792	Asynchronously rmdir (delete) a directory and call the callback with the
680	result code.	793	result code.
681		794
		795	On systems that support the AIO::WD working directory abstraction
		796	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		797	C<rmdir> is called on the absolute path of C<$wd>.
		798
682		799
683	=item aio_readdir $pathname, $callback->($entries)	800	=item aio_readdir $pathname, $callback->($entries)
684		801
685	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	802	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
686	directory (i.e. opendir + readdir + closedir). The entries will not be	803	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
701		818
702	=over 4	819	=over 4
703		820
704	=item IO::AIO::READDIR_DENTS	821	=item IO::AIO::READDIR_DENTS
705		822
706	When this flag is off, then the callback gets an arrayref consisting of	823	Normally the callback gets an arrayref consisting of names only (as
707	names only (as with C<aio_readdir>), otherwise it gets an arrayref with	824	with C<aio_readdir>). If this flag is set, then the callback gets an
708	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	825	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
709	entry in more detail.	826	single directory entry in more detail:
710		827
711	C<$name> is the name of the entry.	828	C<$name> is the name of the entry.
712		829
713	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	830	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
714		831
715	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	832	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
716	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	833	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
717	C<IO::AIO::DT_WHT>.	834	C<IO::AIO::DT_WHT>.
718		835
719	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	836	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
720	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	837	to know, you have to run stat yourself. Also, for speed/memory reasons,
721	scalars are read-only: you can not modify them.	838	the C<$type> scalars are read-only: you must not modify them.
722		839
723	C<$inode> is the inode number (which might not be exact on systems with 64	840	C<$inode> is the inode number (which might not be exact on systems with 64
724	bit inode numbers and 32 bit perls). This field has unspecified content on	841	bit inode numbers and 32 bit perls). This field has unspecified content on
725	systems that do not deliver the inode information.	842	systems that do not deliver the inode information.
726		843
…		…
737	short names are tried first.	854	short names are tried first.
738		855
739	=item IO::AIO::READDIR_STAT_ORDER	856	=item IO::AIO::READDIR_STAT_ORDER
740		857
741	When this flag is set, then the names will be returned in an order	858	When this flag is set, then the names will be returned in an order
742	suitable for stat()'ing each one. That is, when you plan to stat()	859	suitable for stat()'ing each one. That is, when you plan to stat() most or
743	all files in the given directory, then the returned order will likely	860	all files in the given directory, then the returned order will likely be
744	be fastest.	861	faster.
745		862
746	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then	863	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
747	the likely dirs come first, resulting in a less optimal stat order.	864	then the likely dirs come first, resulting in a less optimal stat order
		865	for stat'ing all entries, but likely a more optimal order for finding
		866	subdirectories.
748		867
749	=item IO::AIO::READDIR_FOUND_UNKNOWN	868	=item IO::AIO::READDIR_FOUND_UNKNOWN
750		869
751	This flag should not be set when calling C<aio_readdirx>. Instead, it	870	This flag should not be set when calling C<aio_readdirx>. Instead, it
752	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	871	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
…		…
754	C<$type>'s are known, which can be used to speed up some algorithms.	873	C<$type>'s are known, which can be used to speed up some algorithms.
755		874
756	=back	875	=back
757		876
758		877
		878	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		879
		880	Opens, reads and closes the given file. The data is put into C<$data>,
		881	which is resized as required.
		882
		883	If C<$offset> is negative, then it is counted from the end of the file.
		884
		885	If C<$length> is zero, then the remaining length of the file is
		886	used. Also, in this case, the same limitations to modifying C<$data> apply
		887	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		888	with C<substr>. If the size of the file is known, specifying a non-zero
		889	C<$length> results in a performance advantage.
		890
		891	This request is similar to the older C<aio_load> request, but since it is
		892	a single request, it might be more efficient to use.
		893
		894	Example: load F</etc/passwd> into C<$passwd>.
		895
		896	my $passwd;
		897	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		898	$_[0] >= 0
		899	or die "/etc/passwd: $!\n";
		900
		901	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		902	print $passwd;
		903	};
		904	IO::AIO::flush;
		905
		906
759	=item aio_load $pathname, $data, $callback->($status)	907	=item aio_load $pathname, $data, $callback->($status)
760		908
761	This is a composite request that tries to fully load the given file into	909	This is a composite request that tries to fully load the given file into
762	memory. Status is the same as with aio_read.	910	memory. Status is the same as with aio_read.
		911
		912	Using C<aio_slurp> might be more efficient, as it is a single request.
763		913
764	=cut	914	=cut
765		915
766	sub aio_load($$;$) {	916	sub aio_load($$;$) {
767	my ($path, undef, $cb) = @_;	917	my ($path, undef, $cb) = @_;
…		…
787	=item aio_copy $srcpath, $dstpath, $callback->($status)	937	=item aio_copy $srcpath, $dstpath, $callback->($status)
788		938
789	Try to copy the I<file> (directories not supported as either source or	939	Try to copy the I<file> (directories not supported as either source or
790	destination) from C<$srcpath> to C<$dstpath> and call the callback with	940	destination) from C<$srcpath> to C<$dstpath> and call the callback with
791	a status of C<0> (ok) or C<-1> (error, see C<$!>).	941	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		942
		943	Existing destination files will be truncated.
792		944
793	This is a composite request that creates the destination file with	945	This is a composite request that creates the destination file with
794	mode 0200 and copies the contents of the source file into it using	946	mode 0200 and copies the contents of the source file into it using
795	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	947	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
796	uid/gid, in that order.	948	uid/gid, in that order.
…		…
906	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1058	Scans a directory (similar to C<aio_readdir>) but additionally tries to
907	efficiently separate the entries of directory C<$path> into two sets of	1059	efficiently separate the entries of directory C<$path> into two sets of
908	names, directories you can recurse into (directories), and ones you cannot	1060	names, directories you can recurse into (directories), and ones you cannot
909	recurse into (everything else, including symlinks to directories).	1061	recurse into (everything else, including symlinks to directories).
910		1062
911	C<aio_scandir> is a composite request that creates of many sub requests_	1063	C<aio_scandir> is a composite request that generates many sub requests.
912	C<$maxreq> specifies the maximum number of outstanding aio requests that	1064	C<$maxreq> specifies the maximum number of outstanding aio requests that
913	this function generates. If it is C<< <= 0 >>, then a suitable default	1065	this function generates. If it is C<< <= 0 >>, then a suitable default
914	will be chosen (currently 4).	1066	will be chosen (currently 4).
915		1067
916	On error, the callback is called without arguments, otherwise it receives	1068	On error, the callback is called without arguments, otherwise it receives
…		…
966		1118
967	my $grp = aio_group $cb;	1119	my $grp = aio_group $cb;
968		1120
969	$maxreq = 4 if $maxreq <= 0;	1121	$maxreq = 4 if $maxreq <= 0;
970		1122
971	# stat once	1123	# get a wd object
972	aioreq_pri $pri;	1124	aioreq_pri $pri;
973	add $grp aio_stat $path, sub {	1125	add $grp aio_wd $path, sub {
		1126	$_[0]
974	return $grp->result () if $_[0];	1127	or return $grp->result ();
975	my $now = time;
976	my $hash1 = join ":", (stat _)[0,1,3,7,9];
977		1128
978	# read the directory entries	1129	my $wd = [shift, "."];
		1130
		1131	# stat once
979	aioreq_pri $pri;	1132	aioreq_pri $pri;
980	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1133	add $grp aio_stat $wd, sub {
981	my $entries = shift
982	or return $grp->result ();	1134	return $grp->result () if $_[0];
		1135	my $now = time;
		1136	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		1137	my $rdxflags = READDIR_DIRS_FIRST;
983		1138
984	# stat the dir another time	1139	if ((stat _)[3] < 2) {
		1140	# at least one non-POSIX filesystem exists
		1141	# that returns useful DT_type values: btrfs,
		1142	# so optimise for this here by requesting dents
		1143	$rdxflags |= READDIR_DENTS;
		1144	}
		1145
		1146	# read the directory entries
985	aioreq_pri $pri;	1147	aioreq_pri $pri;
986	add $grp aio_stat $path, sub {	1148	add $grp aio_readdirx $wd, $rdxflags, sub {
987	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1149	my ($entries, $flags) = @_
		1150	or return $grp->result ();
988		1151
		1152	if ($rdxflags & READDIR_DENTS) {
		1153	# if we requested type values, see if we can use them directly.
		1154
		1155	# if there were any DT_UNKNOWN entries then we assume we
		1156	# don't know. alternatively, we could assume that if we get
		1157	# one DT_DIR, then all directories are indeed marked with
		1158	# DT_DIR, but this seems not required for btrfs, and this
		1159	# is basically the "btrfs can't get it's act together" code
		1160	# branch.
		1161	unless ($flags & READDIR_FOUND_UNKNOWN) {
		1162	# now we have valid DT_ information for all entries,
		1163	# so use it as an optimisation without further stat's.
		1164	# they must also all be at the beginning of @$entries
		1165	# by now.
		1166
989	my $ndirs;	1167	my $dirs;
990		1168
991	# take the slow route if anything looks fishy
992	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
993	$ndirs = -1;
994	} else {
995	# if nlink == 2, we are finished
996	# for non-posix-fs's, we rely on nlink < 2
997	$ndirs = (stat _)[3] - 2
998	or return $grp->result ([], $entries);
999	}
1000
1001	my (@dirs, @nondirs);
1002
1003	my $statgrp = add $grp aio_group sub {
1004	$grp->result (\@dirs, \@nondirs);
1005	};
1006
1007	limit $statgrp $maxreq;
1008	feed $statgrp sub {
1009	return unless @$entries;
1010	my $entry = shift @$entries;
1011
1012	aioreq_pri $pri;
1013	add $statgrp aio_stat "$path/$entry/.", sub {
1014	if ($_[0] < 0) {	1169	if (@$entries) {
1015	push @nondirs, $entry;	1170	for (0 .. $#$entries) {
1016	} else {	1171	if ($entries->[$_][1] != DT_DIR) {
1017	# need to check for real directory	1172	# splice out directories
1018	aioreq_pri $pri;	1173	$dirs = [splice @$entries, 0, $_];
1019	add $statgrp aio_lstat "$path/$entry", sub {
1020	if (-d _) {
1021	push @dirs, $entry;
1022
1023	unless (--$ndirs) {
1024	push @nondirs, @$entries;
1025	feed $statgrp;
1026	}	1174	last;
1027	} else {
1028	push @nondirs, $entry;
1029	}	1175	}
1030	}	1176	}
		1177
		1178	# if we didn't find any non-dir, then all entries are dirs
		1179	unless ($dirs) {
		1180	($dirs, $entries) = ($entries, []);
		1181	}
		1182	} else {
		1183	# directory is empty, so there are no sbdirs
		1184	$dirs = [];
1031	}	1185	}
		1186
		1187	# either splice'd the directories out or the dir was empty.
		1188	# convert dents to filenames
		1189	$_ = $_->[0] for @$dirs;
		1190	$_ = $_->[0] for @$entries;
		1191
		1192	return $grp->result ($dirs, $entries);
		1193	}
		1194
		1195	# cannot use, so return to our old ways
		1196	# by pretending we only scanned for names.
		1197	$_ = $_->[0] for @$entries;
		1198	}
		1199
		1200	# stat the dir another time
		1201	aioreq_pri $pri;
		1202	add $grp aio_stat $wd, sub {
		1203	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		1204
		1205	my $ndirs;
		1206
		1207	# take the slow route if anything looks fishy
		1208	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
		1209	$ndirs = -1;
		1210	} else {
		1211	# if nlink == 2, we are finished
		1212	# for non-posix-fs's, we rely on nlink < 2
		1213	$ndirs = (stat _)[3] - 2
		1214	or return $grp->result ([], $entries);
		1215	}
		1216
		1217	my (@dirs, @nondirs);
		1218
		1219	my $statgrp = add $grp aio_group sub {
		1220	$grp->result (\@dirs, \@nondirs);
		1221	};
		1222
		1223	limit $statgrp $maxreq;
		1224	feed $statgrp sub {
		1225	return unless @$entries;
		1226	my $entry = shift @$entries;
		1227
		1228	aioreq_pri $pri;
		1229	$wd->[1] = "$entry/.";
		1230	add $statgrp aio_stat $wd, sub {
		1231	if ($_[0] < 0) {
		1232	push @nondirs, $entry;
		1233	} else {
		1234	# need to check for real directory
		1235	aioreq_pri $pri;
		1236	$wd->[1] = $entry;
		1237	add $statgrp aio_lstat $wd, sub {
		1238	if (-d _) {
		1239	push @dirs, $entry;
		1240
		1241	unless (--$ndirs) {
		1242	push @nondirs, @$entries;
		1243	feed $statgrp;
		1244	}
		1245	} else {
		1246	push @nondirs, $entry;
		1247	}
		1248	}
		1249	}
		1250	};
1032	};	1251	};
1033	};	1252	};
1034	};	1253	};
1035	};	1254	};
1036	};	1255	};
…		…
1039	}	1258	}
1040		1259
1041	=item aio_rmtree $pathname, $callback->($status)	1260	=item aio_rmtree $pathname, $callback->($status)
1042		1261
1043	Delete a directory tree starting (and including) C<$path>, return the	1262	Delete a directory tree starting (and including) C<$path>, return the
1044	status of the final C<rmdir> only. This is a composite request that	1263	status of the final C<rmdir> only. This is a composite request that
1045	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1264	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1046	everything else.	1265	everything else.
1047		1266
1048	=cut	1267	=cut
1049		1268
…		…
1070	add $grp $dirgrp;	1289	add $grp $dirgrp;
1071	};	1290	};
1072		1291
1073	$grp	1292	$grp
1074	}	1293	}
		1294
		1295	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1296
		1297	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1298
		1299	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1300	they execute asynchronously and pass the return value to the callback.
		1301
		1302	Both calls can be used for a lot of things, some of which make more sense
		1303	to run asynchronously in their own thread, while some others make less
		1304	sense. For example, calls that block waiting for external events, such
		1305	as locking, will also lock down an I/O thread while it is waiting, which
		1306	can deadlock the whole I/O system. At the same time, there might be no
		1307	alternative to using a thread to wait.
		1308
		1309	So in general, you should only use these calls for things that do
		1310	(filesystem) I/O, not for things that wait for other events (network,
		1311	other processes), although if you are careful and know what you are doing,
		1312	you still can.
		1313
		1314	The following constants are available and can be used for normal C<ioctl>
		1315	and C<fcntl> as well (missing ones are, as usual C<0>):
		1316
		1317	C<F_DUPFD_CLOEXEC>,
		1318
		1319	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1320
		1321	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1322
		1323	C<F_ADD_SEALS>, C<F_GET_SEALS>, C<F_SEAL_SEAL>, C<F_SEAL_SHRINK>, C<F_SEAL_GROW> and
		1324	C<F_SEAL_WRITE>.
		1325
		1326	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1327	C<FS_IOC_FIEMAP>.
		1328
		1329	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1330	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1331
		1332	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1333	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1334	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1335	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1336	C<FS_FL_USER_MODIFIABLE>.
		1337
		1338	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1339	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1340	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1341	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
1075		1342
1076	=item aio_sync $callback->($status)	1343	=item aio_sync $callback->($status)
1077		1344
1078	Asynchronously call sync and call the callback when finished.	1345	Asynchronously call sync and call the callback when finished.
1079		1346
…		…
1148	};	1415	};
1149		1416
1150	$grp	1417	$grp
1151	}	1418	}
1152		1419
1153	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1420	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1154		1421
1155	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1422	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1156	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1423	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1157	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1424	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1158	scalar must only be modified in-place while an aio operation is pending on	1425	scalar must only be modified in-place while an aio operation is pending on
…		…
1160		1427
1161	It calls the C<msync> function of your OS, if available, with the memory	1428	It calls the C<msync> function of your OS, if available, with the memory
1162	area starting at C<$offset> in the string and ending C<$length> bytes	1429	area starting at C<$offset> in the string and ending C<$length> bytes
1163	later. If C<$length> is negative, counts from the end, and if C<$length>	1430	later. If C<$length> is negative, counts from the end, and if C<$length>
1164	is C<undef>, then it goes till the end of the string. The flags can be	1431	is C<undef>, then it goes till the end of the string. The flags can be
1165	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1432	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1166	C<IO::AIO::MS_SYNC>.	1433	C<IO::AIO::MS_INVALIDATE>.
1167		1434
1168	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1435	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1169		1436
1170	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1437	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1171	scalars.	1438	scalars.
1172		1439
1173	It touches (reads or writes) all memory pages in the specified	1440	It touches (reads or writes) all memory pages in the specified
1174	range inside the scalar. All caveats and parameters are the same	1441	range inside the scalar. All caveats and parameters are the same
1175	as for C<aio_msync>, above, except for flags, which must be either	1442	as for C<aio_msync>, above, except for flags, which must be either
1176	C<0> (which reads all pages and ensures they are instantiated) or	1443	C<0> (which reads all pages and ensures they are instantiated) or
1177	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1444	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1178	writing an octet from it, which dirties the page).	1445	writing an octet from it, which dirties the page).
1179		1446
1180	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1447	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1181		1448
1182	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1449	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1201	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;	1468	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1202	aio_mlock $data; # mlock in background	1469	aio_mlock $data; # mlock in background
1203		1470
1204	=item aio_mlockall $flags, $callback->($status)	1471	=item aio_mlockall $flags, $callback->($status)
1205		1472
1206	Calls the C<mlockall> function with the given C<$flags> (a combination of	1473	Calls the C<mlockall> function with the given C<$flags> (a
1207	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).	1474	combination of C<IO::AIO::MCL_CURRENT>, C<IO::AIO::MCL_FUTURE> and
		1475	C<IO::AIO::MCL_ONFAULT>).
1208		1476
1209	On systems that do not implement C<mlockall>, this function returns C<-1>	1477	On systems that do not implement C<mlockall>, this function returns C<-1>
1210	and sets errno to C<ENOSYS>.	1478	and sets errno to C<ENOSYS>. Similarly, flag combinations not supported
		1479	by the system result in a return value of C<-1> with errno being set to
		1480	C<EINVAL>.
1211		1481
1212	Note that the corresponding C<munlockall> is synchronous and is	1482	Note that the corresponding C<munlockall> is synchronous and is
1213	documented under L<MISCELLANEOUS FUNCTIONS>.	1483	documented under L<MISCELLANEOUS FUNCTIONS>.
1214		1484
1215	Example: asynchronously lock all current and future pages into memory.	1485	Example: asynchronously lock all current and future pages into memory.
1216		1486
1217	aio_mlockall IO::AIO::MCL_FUTURE;	1487	aio_mlockall IO::AIO::MCL_FUTURE;
		1488
		1489	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1490
		1491	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1492	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1493	the ioctl is not available on your OS, then this request will fail with
		1494	C<ENOSYS>.
		1495
		1496	C<$start> is the starting offset to query extents for, C<$length> is the
		1497	size of the range to query - if it is C<undef>, then the whole file will
		1498	be queried.
		1499
		1500	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1501	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1502	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1503	the data portion.
		1504
		1505	C<$count> is the maximum number of extent records to return. If it is
		1506	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1507	case, if it is C<0>, then the callback receives the number of extents
		1508	instead of the extents themselves (which is unreliable, see below).
		1509
		1510	If an error occurs, the callback receives no arguments. The special
		1511	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1512
		1513	Otherwise, the callback receives an array reference with extent
		1514	structures. Each extent structure is an array reference itself, with the
		1515	following members:
		1516
		1517	[$logical, $physical, $length, $flags]
		1518
		1519	Flags is any combination of the following flag values (typically either C<0>
		1520	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1521
		1522	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1523	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1524	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1525	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1526	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1527	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1528
		1529	At the time of this writing (Linux 3.2), this request is unreliable unless
		1530	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1531	it to return all extents of a range for files with a large number of
		1532	extents. The code (only) works around all these issues if C<$count> is
		1533	C<undef>.
1218		1534
1219	=item aio_group $callback->(...)	1535	=item aio_group $callback->(...)
1220		1536
1221	This is a very special aio request: Instead of doing something, it is a	1537	This is a very special aio request: Instead of doing something, it is a
1222	container for other aio requests, which is useful if you want to bundle	1538	container for other aio requests, which is useful if you want to bundle
…		…
1286	object. This object stores the canonicalised, absolute version of the	1602	object. This object stores the canonicalised, absolute version of the
1287	path, and on systems that allow it, also a directory file descriptor.	1603	path, and on systems that allow it, also a directory file descriptor.
1288		1604
1289	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>	1605	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1290	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD	1606	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1291	object and a pathname instead. If the pathname is absolute, the	1607	object and a pathname instead (or the IO::AIO::WD object alone, which
		1608	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1292	IO::AIO::WD objetc is ignored, otherwise the pathname is resolved relative	1609	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1293	to that IO::AIO::WD object.	1610	to that IO::AIO::WD object.
1294		1611
1295	For example, to get a wd object for F</etc> and then stat F<passwd>	1612	For example, to get a wd object for F</etc> and then stat F<passwd>
1296	inside, you would write:	1613	inside, you would write:
1297		1614
…		…
1305	aio_stat [$etcdir, "passwd"], sub {	1622	aio_stat [$etcdir, "passwd"], sub {
1306	# yay	1623	# yay
1307	};	1624	};
1308	};	1625	};
1309		1626
		1627	The fact that C<aio_wd> is a request and not a normal function shows that
1310	This shows that creating an IO::AIO::WD object is itself a potentially	1628	creating an IO::AIO::WD object is itself a potentially blocking operation,
1311	blocking operation, which is why it is done asynchronously.	1629	which is why it is done asynchronously.
		1630
		1631	To stat the directory obtained with C<aio_wd> above, one could write
		1632	either of the following three request calls:
		1633
		1634	aio_lstat "/etc" , sub { ... # pathname as normal string
		1635	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1636	aio_lstat $wd , sub { ... # shorthand for the previous
1312		1637
1313	As with normal pathnames, IO::AIO keeps a copy of the working directory	1638	As with normal pathnames, IO::AIO keeps a copy of the working directory
1314	object and the pathname string, so you could write the following without	1639	object and the pathname string, so you could write the following without
1315	causing any issues due to C<$path> getting reused:	1640	causing any issues due to C<$path> getting reused:
1316		1641
…		…
1326	There are some caveats: when directories get renamed (or deleted), the	1651	There are some caveats: when directories get renamed (or deleted), the
1327	pathname string doesn't change, so will point to the new directory (or	1652	pathname string doesn't change, so will point to the new directory (or
1328	nowhere at all), while the directory fd, if available on the system,	1653	nowhere at all), while the directory fd, if available on the system,
1329	will still point to the original directory. Most functions accepting a	1654	will still point to the original directory. Most functions accepting a
1330	pathname will use the directory fd on newer systems, and the string on	1655	pathname will use the directory fd on newer systems, and the string on
1331	older systems. Some functions (such as realpath) will always rely on the	1656	older systems. Some functions (such as C<aio_realpath>) will always rely on
1332	string form of the pathname.	1657	the string form of the pathname.
1333		1658
1334	So this fucntionality is mainly useful to get some protection against	1659	So this functionality is mainly useful to get some protection against
1335	C<chdir>, to easily get an absolute path out of a relative path for future	1660	C<chdir>, to easily get an absolute path out of a relative path for future
1336	reference, and to speed up doing many operations in the same directory	1661	reference, and to speed up doing many operations in the same directory
1337	(e.g. when stat'ing all files in a directory).	1662	(e.g. when stat'ing all files in a directory).
1338		1663
1339	The following functions implement this working directory abstraction:	1664	The following functions implement this working directory abstraction:
…		…
1352	passing C<undef> as working directory component of a pathname fails the	1677	passing C<undef> as working directory component of a pathname fails the
1353	request with C<ENOENT>, there is often no need for error checking in the	1678	request with C<ENOENT>, there is often no need for error checking in the
1354	C<aio_wd> callback, as future requests using the value will fail in the	1679	C<aio_wd> callback, as future requests using the value will fail in the
1355	expected way.	1680	expected way.
1356		1681
1357	If this call isn't available because your OS lacks it or it couldn't be
1358	detected, it will be emulated by calling C<fsync> instead.
1359
1360	=item IO::AIO::CWD	1682	=item IO::AIO::CWD
1361		1683
1362	This is a compiletime constant (object) that represents the process	1684	This is a compile time constant (object) that represents the process
1363	current working directory.	1685	current working directory.
1364		1686
1365	Specifying this object as working directory object for a pathname is as	1687	Specifying this object as working directory object for a pathname is as if
1366	if the pathname would be specified directly, without a directory object,	1688	the pathname would be specified directly, without a directory object. For
1367	e.g., these calls are functionally identical:	1689	example, these calls are functionally identical:
1368		1690
1369	aio_stat "somefile", sub { ... };	1691	aio_stat "somefile", sub { ... };
1370	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };	1692	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1371		1693
1372	=back	1694	=back
1373		1695
		1696	To recover the path associated with an IO::AIO::WD object, you can use
		1697	C<aio_realpath>:
		1698
		1699	aio_realpath $wd, sub {
		1700	warn "path is $_[0]\n";
		1701	};
		1702
		1703	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1704	sometimes, fall back to using an absolue path.
1374		1705
1375	=head2 IO::AIO::REQ CLASS	1706	=head2 IO::AIO::REQ CLASS
1376		1707
1377	All non-aggregate C<aio_*> functions return an object of this class when	1708	All non-aggregate C<aio_*> functions return an object of this class when
1378	called in non-void context.	1709	called in non-void context.
…		…
1496		1827
1497	Sets a feeder/generator on this group: every group can have an attached	1828	Sets a feeder/generator on this group: every group can have an attached
1498	generator that generates requests if idle. The idea behind this is that,	1829	generator that generates requests if idle. The idea behind this is that,
1499	although you could just queue as many requests as you want in a group,	1830	although you could just queue as many requests as you want in a group,
1500	this might starve other requests for a potentially long time. For example,	1831	this might starve other requests for a potentially long time. For example,
1501	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1832	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1502	delaying any later requests for a long time.	1833	requests, delaying any later requests for a long time.
1503		1834
1504	To avoid this, and allow incremental generation of requests, you can	1835	To avoid this, and allow incremental generation of requests, you can
1505	instead a group and set a feeder on it that generates those requests. The	1836	instead a group and set a feeder on it that generates those requests. The
1506	feed callback will be called whenever there are few enough (see C<limit>,	1837	feed callback will be called whenever there are few enough (see C<limit>,
1507	below) requests active in the group itself and is expected to queue more	1838	below) requests active in the group itself and is expected to queue more
…		…
1539	The default value for the limit is C<0>, but note that setting a feeder	1870	The default value for the limit is C<0>, but note that setting a feeder
1540	automatically bumps it up to C<2>.	1871	automatically bumps it up to C<2>.
1541		1872
1542	=back	1873	=back
1543		1874
		1875
1544	=head2 SUPPORT FUNCTIONS	1876	=head2 SUPPORT FUNCTIONS
1545		1877
1546	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1878	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1547		1879
1548	=over 4	1880	=over 4
…		…
1556		1888
1557	See C<poll_cb> for an example.	1889	See C<poll_cb> for an example.
1558		1890
1559	=item IO::AIO::poll_cb	1891	=item IO::AIO::poll_cb
1560		1892
1561	Process some outstanding events on the result pipe. You have to call	1893	Process some requests that have reached the result phase (i.e. they have
		1894	been executed but the results are not yet reported). You have to call
		1895	this "regularly" to finish outstanding requests.
		1896
1562	this regularly. Returns C<0> if all events could be processed (or there	1897	Returns C<0> if all events could be processed (or there were no
1563	were no events to process), or C<-1> if it returned earlier for whatever	1898	events to process), or C<-1> if it returned earlier for whatever
1564	reason. Returns immediately when no events are outstanding. The amount of	1899	reason. Returns immediately when no events are outstanding. The amount
1565	events processed depends on the settings of C<IO::AIO::max_poll_req> and	1900	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1566	C<IO::AIO::max_poll_time>.	1901	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1567		1902
1568	If not all requests were processed for whatever reason, the filehandle	1903	If not all requests were processed for whatever reason, the poll file
1569	will still be ready when C<poll_cb> returns, so normally you don't have to	1904	descriptor will still be ready when C<poll_cb> returns, so normally you
1570	do anything special to have it called later.	1905	don't have to do anything special to have it called later.
1571		1906
1572	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1907	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1573	ready, it can be beneficial to call this function from loops which submit	1908	ready, it can be beneficial to call this function from loops which submit
1574	a lot of requests, to make sure the results get processed when they become	1909	a lot of requests, to make sure the results get processed when they become
1575	available and not just when the loop is finished and the event loop takes	1910	available and not just when the loop is finished and the event loop takes
…		…
1584	poll => 'r', async => 1,	1919	poll => 'r', async => 1,
1585	cb => \&IO::AIO::poll_cb);	1920	cb => \&IO::AIO::poll_cb);
1586		1921
1587	=item IO::AIO::poll_wait	1922	=item IO::AIO::poll_wait
1588		1923
1589	If there are any outstanding requests and none of them in the result	1924	Wait until either at least one request is in the result phase or no
1590	phase, wait till the result filehandle becomes ready for reading (simply	1925	requests are outstanding anymore.
1591	does a C<select> on the filehandle. This is useful if you want to	1926
1592	synchronously wait for some requests to finish).	1927	This is useful if you want to synchronously wait for some requests to
		1928	become ready, without actually handling them.
1593		1929
1594	See C<nreqs> for an example.	1930	See C<nreqs> for an example.
1595		1931
1596	=item IO::AIO::poll	1932	=item IO::AIO::poll
1597		1933
…		…
1608		1944
1609	Strictly equivalent to:	1945	Strictly equivalent to:
1610		1946
1611	IO::AIO::poll_wait, IO::AIO::poll_cb	1947	IO::AIO::poll_wait, IO::AIO::poll_cb
1612	while IO::AIO::nreqs;	1948	while IO::AIO::nreqs;
		1949
		1950	This function can be useful at program aborts, to make sure outstanding
		1951	I/O has been done (C<IO::AIO> uses an C<END> block which already calls
		1952	this function on normal exits), or when you are merely using C<IO::AIO>
		1953	for its more advanced functions, rather than for async I/O, e.g.:
		1954
		1955	my ($dirs, $nondirs);
		1956	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1957	IO::AIO::flush;
		1958	# $dirs, $nondirs are now set
1613		1959
1614	=item IO::AIO::max_poll_reqs $nreqs	1960	=item IO::AIO::max_poll_reqs $nreqs
1615		1961
1616	=item IO::AIO::max_poll_time $seconds	1962	=item IO::AIO::max_poll_time $seconds
1617		1963
…		…
1644	poll => 'r', nice => 1,	1990	poll => 'r', nice => 1,
1645	cb => &IO::AIO::poll_cb);	1991	cb => &IO::AIO::poll_cb);
1646		1992
1647	=back	1993	=back
1648		1994
		1995
1649	=head3 CONTROLLING THE NUMBER OF THREADS	1996	=head3 CONTROLLING THE NUMBER OF THREADS
1650		1997
1651	=over	1998	=over
1652		1999
1653	=item IO::AIO::min_parallel $nthreads	2000	=item IO::AIO::min_parallel $nthreads
…		…
1718		2065
1719	This is a very bad function to use in interactive programs because it	2066	This is a very bad function to use in interactive programs because it
1720	blocks, and a bad way to reduce concurrency because it is inexact: Better	2067	blocks, and a bad way to reduce concurrency because it is inexact: Better
1721	use an C<aio_group> together with a feed callback.	2068	use an C<aio_group> together with a feed callback.
1722		2069
1723	It's main use is in scripts without an event loop - when you want to stat	2070	Its main use is in scripts without an event loop - when you want to stat
1724	a lot of files, you can write somehting like this:	2071	a lot of files, you can write something like this:
1725		2072
1726	IO::AIO::max_outstanding 32;	2073	IO::AIO::max_outstanding 32;
1727		2074
1728	for my $path (...) {	2075	for my $path (...) {
1729	aio_stat $path , ...;	2076	aio_stat $path , ...;
…		…
1740	The default value for C<max_outstanding> is very large, so there is no	2087	The default value for C<max_outstanding> is very large, so there is no
1741	practical limit on the number of outstanding requests.	2088	practical limit on the number of outstanding requests.
1742		2089
1743	=back	2090	=back
1744		2091
		2092
1745	=head3 STATISTICAL INFORMATION	2093	=head3 STATISTICAL INFORMATION
1746		2094
1747	=over	2095	=over
1748		2096
1749	=item IO::AIO::nreqs	2097	=item IO::AIO::nreqs
…		…
1766	Returns the number of requests currently in the pending state (executed,	2114	Returns the number of requests currently in the pending state (executed,
1767	but not yet processed by poll_cb).	2115	but not yet processed by poll_cb).
1768		2116
1769	=back	2117	=back
1770		2118
		2119
		2120	=head3 SUBSECOND STAT TIME ACCESS
		2121
		2122	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2123	generally find access/modification and change times with subsecond time
		2124	accuracy of the system supports it, but perl's built-in functions only
		2125	return the integer part.
		2126
		2127	The following functions return the timestamps of the most recent
		2128	stat with subsecond precision on most systems and work both after
		2129	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2130	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2131	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2132
		2133	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2134	full resolution without rounding and work with standard perl C<stat>,
		2135	alleviating the need to call the special C<Time::HiRes> functions, which
		2136	do not act like their perl counterparts.
		2137
		2138	On operating systems or file systems where subsecond time resolution is
		2139	not supported or could not be detected, a fractional part of C<0> is
		2140	returned, so it is always safe to call these functions.
		2141
		2142	=over 4
		2143
		2144	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		2145
		2146	Return the access, modication, change or birth time, respectively,
		2147	including fractional part. Due to the limited precision of floating point,
		2148	the accuracy on most platforms is only a bit better than milliseconds
		2149	for times around now - see the I<nsec> function family, below, for full
		2150	accuracy.
		2151
		2152	File birth time is only available when the OS and perl support it (on
		2153	FreeBSD and NetBSD at the time of this writing, although support is
		2154	adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
		2155	it). On systems where it isn't available, C<0> is currently returned, but
		2156	this might change to C<undef> in a future version.
		2157
		2158	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		2159
		2160	Returns access, modification, change and birth time all in one go, and
		2161	maybe more times in the future version.
		2162
		2163	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		2164
		2165	Return the fractional access, modifcation, change or birth time, in nanoseconds,
		2166	as an integer in the range C<0> to C<999999999>.
		2167
		2168	Note that no accessors are provided for access, modification and
		2169	change times - you need to get those from C<stat _> if required (C<int
		2170	IO::AIO::st_atime> and so on will I<not> generally give you the correct
		2171	value).
		2172
		2173	=item $seconds = IO::AIO::st_btimesec
		2174
		2175	The (integral) seconds part of the file birth time, if available.
		2176
		2177	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		2178
		2179	Like the functions above, but returns all four times in one go (and maybe
		2180	more in future versions).
		2181
		2182	=item $counter = IO::AIO::st_gen
		2183
		2184	Returns the generation counter (in practice this is just a random number)
		2185	of the file. This is only available on platforms which have this member in
		2186	their C<struct stat> (most BSDs at the time of this writing) and generally
		2187	only to the root usert. If unsupported, C<0> is returned, but this might
		2188	change to C<undef> in a future version.
		2189
		2190	=back
		2191
		2192	Example: print the high resolution modification time of F</etc>, using
		2193	C<stat>, and C<IO::AIO::aio_stat>.
		2194
		2195	if (stat "/etc") {
		2196	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2197	}
		2198
		2199	IO::AIO::aio_stat "/etc", sub {
		2200	$_[0]
		2201	and return;
		2202
		2203	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2204	};
		2205
		2206	IO::AIO::flush;
		2207
		2208	Output of the awbove on my system, showing reduced and full accuracy:
		2209
		2210	stat(/etc) mtime: 1534043702.020808
		2211	aio_stat(/etc) mtime: 1534043702.020807792
		2212
		2213
1771	=head3 MISCELLANEOUS FUNCTIONS	2214	=head3 MISCELLANEOUS FUNCTIONS
1772		2215
1773	IO::AIO implements some functions that might be useful, but are not	2216	IO::AIO implements some functions that are useful when you want to use
1774	asynchronous.	2217	some "Advanced I/O" function not available to in Perl, without going the
		2218	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2219	counterpart.
1775		2220
1776	=over 4	2221	=over 4
		2222
		2223	=item $numfd = IO::AIO::get_fdlimit
		2224
		2225	This function is I<EXPERIMENTAL> and subject to change.
		2226
		2227	Tries to find the current file descriptor limit and returns it, or
		2228	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2229	the highest valid file descriptor number.
		2230
		2231	=item IO::AIO::min_fdlimit [$numfd]
		2232
		2233	This function is I<EXPERIMENTAL> and subject to change.
		2234
		2235	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2236	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2237	is missing, it will try to set a very high limit, although this is not
		2238	recommended when you know the actual minimum that you require.
		2239
		2240	If the limit cannot be raised enough, the function makes a best-effort
		2241	attempt to increase the limit as much as possible, using various
		2242	tricks, while still failing. You can query the resulting limit using
		2243	C<IO::AIO::get_fdlimit>.
		2244
		2245	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2246	true.
1777		2247
1778	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2248	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1779		2249
1780	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2250	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1781	but is blocking (this makes most sense if you know the input data is	2251	but is blocking (this makes most sense if you know the input data is
…		…
1798	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2268	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1799		2269
1800	Simply calls the C<posix_madvise> function (see its	2270	Simply calls the C<posix_madvise> function (see its
1801	manpage for details). The following advice constants are	2271	manpage for details). The following advice constants are
1802	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2272	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1803	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2273	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2274	C<IO::AIO::MADV_DONTNEED>.
		2275
		2276	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2277	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2278	will be reduced to fit into the C<$scalar>.
1804		2279
1805	On systems that do not implement C<posix_madvise>, this function returns	2280	On systems that do not implement C<posix_madvise>, this function returns
1806	ENOSYS, otherwise the return value of C<posix_madvise>.	2281	ENOSYS, otherwise the return value of C<posix_madvise>.
1807		2282
1808	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2283	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
…		…
1810	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2285	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1811	$scalar (see its manpage for details). The following protect	2286	$scalar (see its manpage for details). The following protect
1812	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2287	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1813	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2288	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1814		2289
		2290	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2291	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2292	will be reduced to fit into the C<$scalar>.
		2293
1815	On systems that do not implement C<mprotect>, this function returns	2294	On systems that do not implement C<mprotect>, this function returns
1816	ENOSYS, otherwise the return value of C<mprotect>.	2295	ENOSYS, otherwise the return value of C<mprotect>.
1817		2296
1818	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2297	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1819		2298
1820	Memory-maps a file (or anonymous memory range) and attaches it to the	2299	Memory-maps a file (or anonymous memory range) and attaches it to the
1821	given C<$scalar>, which will act like a string scalar.	2300	given C<$scalar>, which will act like a string scalar. Returns true on
		2301	success, and false otherwise.
1822		2302
		2303	The scalar must exist, but its contents do not matter - this means you
		2304	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2305	the scalar first.
		2306
1823	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2307	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1824	change the string length, and most read-only operations such as copying it	2308	which don't change the string length, and most read-only operations such
1825	or searching it with regexes and so on.	2309	as copying it or searching it with regexes and so on.
1826		2310
1827	Anything else is unsafe and will, at best, result in memory leaks.	2311	Anything else is unsafe and will, at best, result in memory leaks.
1828		2312
1829	The memory map associated with the C<$scalar> is automatically removed	2313	The memory map associated with the C<$scalar> is automatically removed
1830	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2314	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1831	C<IO::AIO::munmap> functions are called.	2315	or C<IO::AIO::munmap> functions are called on it.
1832		2316
1833	This calls the C<mmap>(2) function internally. See your system's manual	2317	This calls the C<mmap>(2) function internally. See your system's manual
1834	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2318	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1835		2319
1836	The C<$length> must be larger than zero and smaller than the actual	2320	The C<$length> must be larger than zero and smaller than the actual
1837	filesize.	2321	filesize.
1838		2322
1839	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2323	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1840	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2324	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1841		2325
1842	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2326	C<$flags> can be a combination of
1843	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2327	C<IO::AIO::MAP_SHARED> or
1844	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2328	C<IO::AIO::MAP_PRIVATE>,
		2329	or a number of system-specific flags (when not available, the are C<0>):
1845	(which is set to C<MAP_ANON> if your system only provides this	2330	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1846	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2331	C<IO::AIO::MAP_LOCKED>,
1847	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2332	C<IO::AIO::MAP_NORESERVE>,
		2333	C<IO::AIO::MAP_POPULATE>,
1848	C<IO::AIO::MAP_NONBLOCK>	2334	C<IO::AIO::MAP_NONBLOCK>,
		2335	C<IO::AIO::MAP_FIXED>,
		2336	C<IO::AIO::MAP_GROWSDOWN>,
		2337	C<IO::AIO::MAP_32BIT>,
		2338	C<IO::AIO::MAP_HUGETLB> or
		2339	C<IO::AIO::MAP_STACK>.
1849		2340
1850	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2341	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1851		2342
1852	C<$offset> is the offset from the start of the file - it generally must be	2343	C<$offset> is the offset from the start of the file - it generally must be
1853	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2344	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1867		2358
1868	=item IO::AIO::munmap $scalar	2359	=item IO::AIO::munmap $scalar
1869		2360
1870	Removes a previous mmap and undefines the C<$scalar>.	2361	Removes a previous mmap and undefines the C<$scalar>.
1871		2362
		2363	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2364
		2365	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2366	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2367	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2368
		2369	Returns true if successful, and false otherwise. If the underlying mmapped
		2370	region has changed address, then the true value has the numerical value
		2371	C<1>, otherwise it has the numerical value C<0>:
		2372
		2373	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2374	or die "mremap: $!";
		2375
		2376	if ($success*1) {
		2377	warn "scalar has chanegd address in memory\n";
		2378	}
		2379
		2380	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2381	implemented, but not supported and might go away in a future version.
		2382
		2383	On systems where this call is not supported or is not emulated, this call
		2384	returns falls and sets C<$!> to C<ENOSYS>.
		2385
		2386	=item IO::AIO::mlockall $flags
		2387
		2388	Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
		2389	but is blocking.
		2390
1872	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef	2391	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1873		2392
1874	Calls the C<munlock> function, undoing the effects of a previous	2393	Calls the C<munlock> function, undoing the effects of a previous
1875	C<aio_mlock> call (see its description for details).	2394	C<aio_mlock> call (see its description for details).
1876		2395
…		…
1878		2397
1879	Calls the C<munlockall> function.	2398	Calls the C<munlockall> function.
1880		2399
1881	On systems that do not implement C<munlockall>, this function returns	2400	On systems that do not implement C<munlockall>, this function returns
1882	ENOSYS, otherwise the return value of C<munlockall>.	2401	ENOSYS, otherwise the return value of C<munlockall>.
		2402
		2403	=item $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		2404
		2405	Uses the GNU/Linux C<accept4(2)> syscall, if available, to accept a socket
		2406	and return the new file handle on success, or sets C<$!> and returns
		2407	C<undef> on error.
		2408
		2409	The remote name of the new socket will be stored in C<$sockaddr>, which
		2410	will be extended to allow for at least C<$sockaddr_maxlen> octets. If the
		2411	socket name does not fit into C<$sockaddr_maxlen> octets, this is signaled
		2412	by returning a longer string in C<$sockaddr>, which might or might not be
		2413	truncated.
		2414
		2415	To accept name-less sockets, use C<undef> for C<$sockaddr> and C<0> for
		2416	C<$sockaddr_maxlen>.
		2417
		2418	The main reasons to use this syscall rather than portable C«accept(2)>
		2419	are that you can specify C<SOCK_NONBLOCK> and/or C<SOCK_CLOEXEC>
		2420	flags and you can accept name-less sockets by specifying C<0> for
		2421	C<$sockaddr_maxlen>, which is sadly not possible with perl's interface to
		2422	C<accept>.
		2423
		2424	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2425
		2426	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2427	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2428	should be the file offset.
		2429
		2430	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2431	silently corrupt the data in this case.
		2432
		2433	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2434	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2435	C<IO::AIO::SPLICE_F_GIFT>.
		2436
		2437	See the C<splice(2)> manpage for details.
		2438
		2439	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2440
		2441	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2442	description for C<IO::AIO::splice> above for details.
		2443
		2444	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2445
		2446	Attempts to query or change the pipe buffer size. Obviously works only
		2447	on pipes, and currently works only on GNU/Linux systems, and fails with
		2448	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2449	size on other systems, drop me a note.
		2450
		2451	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2452
		2453	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2454	C<$flags> is missing or C<0>, then this should be the same as a call to
		2455	perl's built-in C<pipe> function and create a new pipe, and works on
		2456	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2457	(..., 4096, O_BINARY)>.
		2458
		2459	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2460	the given flags (Linux 2.6.27, glibc 2.9).
		2461
		2462	On success, the read and write file handles are returned.
		2463
		2464	On error, nothing will be returned. If the pipe2 syscall is missing and
		2465	C<$flags> is non-zero, fails with C<ENOSYS>.
		2466
		2467	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2468	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2469	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2470
		2471	Example: create a pipe race-free w.r.t. threads and fork:
		2472
		2473	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2474	or die "pipe2: $!\n";
		2475
		2476	=item $fh = IO::AIO::memfd_create $pathname[, $flags]
		2477
		2478	This is a direct interface to the Linux L<memfd_create(2)> system
		2479	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2480	should be C<IO::AIO::MFD_CLOEXEC>.
		2481
		2482	On success, the new memfd filehandle is returned, otherwise returns
		2483	C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
		2484
		2485	Please refer to L<memfd_create(2)> for more info on this call.
		2486
		2487	The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
		2488	C<IO::AIO::MFD_ALLOW_SEALING> and C<IO::AIO::MFD_HUGETLB>.
		2489
		2490	Example: create a new memfd.
		2491
		2492	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2493	or die "m,emfd_create: $!\n";
		2494	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2495
		2496	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2497	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2498
		2499	On success, the new eventfd filehandle is returned, otherwise returns
		2500	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2501
		2502	Please refer to L<eventfd(2)> for more info on this call.
		2503
		2504	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2505	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2506
		2507	Example: create a new eventfd filehandle:
		2508
		2509	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2510	or die "eventfd: $!\n";
		2511
		2512	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2513
		2514	This is a direct interface to the Linux L<timerfd_create(2)> system
		2515	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2516	should be C<IO::AIO::TFD_CLOEXEC>.
		2517
		2518	On success, the new timerfd filehandle is returned, otherwise returns
		2519	C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
		2520
		2521	Please refer to L<timerfd_create(2)> for more info on this call.
		2522
		2523	The following C<$clockid> values are
		2524	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2525	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2526	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2527	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2528
		2529	The following C<$flags> values are available (Linux
		2530	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2531
		2532	Example: create a new timerfd and set it to one-second repeated alarms,
		2533	then wait for two alarms:
		2534
		2535	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2536	or die "timerfd_create: $!\n";
		2537
		2538	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2539	or die "timerfd_settime: $!\n";
		2540
		2541	for (1..2) {
		2542	8 == sysread $fh, my $buf, 8
		2543	or die "timerfd read failure\n";
		2544
		2545	printf "number of expirations (likely 1): %d\n",
		2546	unpack "Q", $buf;
		2547	}
		2548
		2549	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2550
		2551	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2552	call. Please refer to its manpage for more info on this call.
		2553
		2554	The new itimerspec is specified using two (possibly fractional) second
		2555	values, C<$new_interval> and C<$new_value>).
		2556
		2557	On success, the current interval and value are returned (as per
		2558	C<timerfd_gettime>). On failure, the empty list is returned.
		2559
		2560	The following C<$flags> values are
		2561	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2562	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2563
		2564	See C<IO::AIO::timerfd_create> for a full example.
		2565
		2566	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2567
		2568	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2569	call. Please refer to its manpage for more info on this call.
		2570
		2571	On success, returns the current values of interval and value for the given
		2572	timerfd (as potentially fractional second values). On failure, the empty
		2573	list is returned.
1883		2574
1884	=back	2575	=back
1885		2576
1886	=cut	2577	=cut
1887		2578
…		…
1953	the process will result in undefined behaviour. Calling it at any time	2644	the process will result in undefined behaviour. Calling it at any time
1954	will also result in any undefined (by POSIX) behaviour.	2645	will also result in any undefined (by POSIX) behaviour.
1955		2646
1956	=back	2647	=back
1957		2648
		2649	=head2 LINUX-SPECIFIC CALLS
		2650
		2651	When a call is documented as "linux-specific" then this means it
		2652	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2653	availability and compatibility of such calls regardless of the platform
		2654	it is compiled on, so platforms such as FreeBSD which often implement
		2655	these calls will work. When in doubt, call them and see if they fail wth
		2656	C<ENOSYS>.
		2657
1958	=head2 MEMORY USAGE	2658	=head2 MEMORY USAGE
1959		2659
1960	Per-request usage:	2660	Per-request usage:
1961		2661
1962	Each aio request uses - depending on your architecture - around 100-200	2662	Each aio request uses - depending on your architecture - around 100-200
…		…
1974	temporary buffers, and each thread requires a stack and other data	2674	temporary buffers, and each thread requires a stack and other data
1975	structures (usually around 16k-128k, depending on the OS).	2675	structures (usually around 16k-128k, depending on the OS).
1976		2676
1977	=head1 KNOWN BUGS	2677	=head1 KNOWN BUGS
1978		2678
1979	Known bugs will be fixed in the next release.	2679	Known bugs will be fixed in the next release :)
		2680
		2681	=head1 KNOWN ISSUES
		2682
		2683	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2684	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2685	non-created hash slots or other scalars I didn't think of. It's best to
		2686	avoid such and either use scalar variables or making sure that the scalar
		2687	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2688
		2689	I am not sure anything can be done about this, so this is considered a
		2690	known issue, rather than a bug.
1980		2691
1981	=head1 SEE ALSO	2692	=head1 SEE ALSO
1982		2693
1983	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2694	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1984	more natural syntax.	2695	more natural syntax and L<IO::FDPass> for file descriptor passing.
1985		2696
1986	=head1 AUTHOR	2697	=head1 AUTHOR
1987		2698
1988	Marc Lehmann <schmorp@schmorp.de>	2699	Marc Lehmann <schmorp@schmorp.de>
1989	http://home.schmorp.de/	2700	http://home.schmorp.de/

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