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Revision 1.209 by root, Tue Sep 27 00:41:51 2011 UTC vs.
Revision 1.315 by root, Mon Sep 5 00:03:32 2022 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	IO::AIO - Asynchronous Input/Output	3	IO::AIO - Asynchronous/Advanced Input/Output
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
…		…
58	not well-supported or restricted (GNU/Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
59	files currently, for example), and they would only support aio_read and	59	files currently, for example), and they would only support aio_read and
60	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
61	using threads anyway.	61	using threads anyway.
62		62
		63	In addition to asynchronous I/O, this module also exports some rather
		64	arcane interfaces, such as C<madvise> or linux's C<splice> system call,
		65	which is why the C<A> in C<AIO> can also mean I<advanced>.
		66
63	Although the module will work in the presence of other (Perl-) threads,	67	Although the module will work in the presence of other (Perl-) threads,
64	it is currently not reentrant in any way, so use appropriate locking	68	it is currently not reentrant in any way, so use appropriate locking
65	yourself, always call C<poll_cb> from within the same thread, or never	69	yourself, always call C<poll_cb> from within the same thread, or never
66	call C<poll_cb> (or other C<aio_> functions) recursively.	70	call C<poll_cb> (or other C<aio_> functions) recursively.
67		71
68	=head2 EXAMPLE	72	=head2 EXAMPLE
69		73
70	This is a simple example that uses the EV module and loads	74	This is a simple example that uses the EV module and loads
71	F</etc/passwd> asynchronously:	75	F</etc/passwd> asynchronously:
72		76
73	use Fcntl;
74	use EV;	77	use EV;
75	use IO::AIO;	78	use IO::AIO;
76		79
77	# register the IO::AIO callback with EV	80	# register the IO::AIO callback with EV
78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	81	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
…		…
95		98
96	# file contents now in $contents	99	# file contents now in $contents
97	print $contents;	100	print $contents;
98		101
99	# exit event loop and program	102	# exit event loop and program
100	EV::unloop;	103	EV::break;
101	};	104	};
102	};	105	};
103		106
104	# possibly queue up other requests, or open GUI windows,	107	# possibly queue up other requests, or open GUI windows,
105	# check for sockets etc. etc.	108	# check for sockets etc. etc.
106		109
107	# process events as long as there are some:	110	# process events as long as there are some:
108	EV::loop;	111	EV::run;
109		112
110	=head1 REQUEST ANATOMY AND LIFETIME	113	=head1 REQUEST ANATOMY AND LIFETIME
111		114
112	Every C<aio_*> function creates a request. which is a C data structure not	115	Every C<aio_*> function creates a request. which is a C data structure not
113	directly visible to Perl.	116	directly visible to Perl.
…		…
168	use common::sense;	171	use common::sense;
169		172
170	use base 'Exporter';	173	use base 'Exporter';
171		174
172	BEGIN {	175	BEGIN {
173	our $VERSION = '4.0';	176	our $VERSION = 4.77;
174		177
175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	178	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx	179	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate	181	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
179	aio_pathsync aio_readahead	182	aio_pathsync aio_readahead aio_fiemap aio_allocate
180	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
181	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	184	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
182	aio_chmod aio_utime aio_truncate	185	aio_chmod aio_utime aio_truncate
183	aio_msync aio_mtouch aio_mlock aio_mlockall	186	aio_msync aio_mtouch aio_mlock aio_mlockall
184	aio_statvfs	187	aio_statvfs
		188	aio_slurp
185	aio_wd);	189	aio_wd);
186		190
187	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	191	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
188	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	192	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
189	min_parallel max_parallel max_idle idle_timeout	193	min_parallel max_parallel max_idle idle_timeout
190	nreqs nready npending nthreads	194	nreqs nready npending nthreads
191	max_poll_time max_poll_reqs	195	max_poll_time max_poll_reqs
192	sendfile fadvise madvise	196	sendfile fadvise madvise
193	mmap munmap munlock munlockall);	197	mmap munmap mremap munlock munlockall
		198
		199	accept4 tee splice pipe2 pipesize
		200	fexecve memfd_create eventfd
		201	timerfd_create timerfd_settime timerfd_gettime
		202	pidfd_open pidfd_send_signal pidfd_getfd);
194		203
195	push @AIO_REQ, qw(aio_busy); # not exported	204	push @AIO_REQ, qw(aio_busy); # not exported
196		205
197	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	206	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
198		207
…		…
202		211
203	=head1 FUNCTIONS	212	=head1 FUNCTIONS
204		213
205	=head2 QUICK OVERVIEW	214	=head2 QUICK OVERVIEW
206		215
207	This section simply lists the prototypes of the most important functions	216	This section simply lists the prototypes most of the functions for
208	for quick reference. See the following sections for function-by-function	217	quick reference. See the following sections for function-by-function
209	documentation.	218	documentation.
210		219
211	aio_wd $pathname, $callback->($wd)	220	aio_wd $pathname, $callback->($wd)
212	aio_open $pathname, $flags, $mode, $callback->($fh)	221	aio_open $pathname, $flags, $mode, $callback->($fh)
213	aio_close $fh, $callback->($status)	222	aio_close $fh, $callback->($status)
		223	aio_seek $fh,$offset,$whence, $callback->($offs)
214	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	224	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
215	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	225	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
216	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	226	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
217	aio_readahead $fh,$offset,$length, $callback->($retval)	227	aio_readahead $fh,$offset,$length, $callback->($retval)
218	aio_stat $fh_or_path, $callback->($status)	228	aio_stat $fh_or_path, $callback->($status)
219	aio_lstat $fh, $callback->($status)	229	aio_lstat $fh, $callback->($status)
220	aio_statvfs $fh_or_path, $callback->($statvfs)	230	aio_statvfs $fh_or_path, $callback->($statvfs)
221	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	231	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
222	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	232	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		233	aio_chmod $fh_or_path, $mode, $callback->($status)
223	aio_truncate $fh_or_path, $offset, $callback->($status)	234	aio_truncate $fh_or_path, $offset, $callback->($status)
224	aio_chmod $fh_or_path, $mode, $callback->($status)	235	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		236	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
225	aio_unlink $pathname, $callback->($status)	237	aio_unlink $pathname, $callback->($status)
226	aio_mknod $pathname, $mode, $dev, $callback->($status)	238	aio_mknod $pathname, $mode, $dev, $callback->($status)
227	aio_link $srcpath, $dstpath, $callback->($status)	239	aio_link $srcpath, $dstpath, $callback->($status)
228	aio_symlink $srcpath, $dstpath, $callback->($status)	240	aio_symlink $srcpath, $dstpath, $callback->($status)
229	aio_readlink $pathname, $callback->($link)	241	aio_readlink $pathname, $callback->($link)
230	aio_realpath $pathname, $callback->($link)	242	aio_realpath $pathname, $callback->($path)
231	aio_rename $srcpath, $dstpath, $callback->($status)	243	aio_rename $srcpath, $dstpath, $callback->($status)
		244	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
232	aio_mkdir $pathname, $mode, $callback->($status)	245	aio_mkdir $pathname, $mode, $callback->($status)
233	aio_rmdir $pathname, $callback->($status)	246	aio_rmdir $pathname, $callback->($status)
234	aio_readdir $pathname, $callback->($entries)	247	aio_readdir $pathname, $callback->($entries)
235	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	248	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
236	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	249	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
237	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	250	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		251	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
238	aio_load $pathname, $data, $callback->($status)	252	aio_load $pathname, $data, $callback->($status)
239	aio_copy $srcpath, $dstpath, $callback->($status)	253	aio_copy $srcpath, $dstpath, $callback->($status)
240	aio_move $srcpath, $dstpath, $callback->($status)	254	aio_move $srcpath, $dstpath, $callback->($status)
241	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
242	aio_rmtree $pathname, $callback->($status)	255	aio_rmtree $pathname, $callback->($status)
		256	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		257	aio_ioctl $fh, $request, $buf, $callback->($status)
243	aio_sync $callback->($status)	258	aio_sync $callback->($status)
244	aio_syncfs $fh, $callback->($status)	259	aio_syncfs $fh, $callback->($status)
245	aio_fsync $fh, $callback->($status)	260	aio_fsync $fh, $callback->($status)
246	aio_fdatasync $fh, $callback->($status)	261	aio_fdatasync $fh, $callback->($status)
247	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	262	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
248	aio_pathsync $pathname, $callback->($status)	263	aio_pathsync $pathname, $callback->($status)
249	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	264	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
250	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	265	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
251	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	266	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
252	aio_mlockall $flags, $callback->($status)	267	aio_mlockall $flags, $callback->($status)
253	aio_group $callback->(...)	268	aio_group $callback->(...)
254	aio_nop $callback->()	269	aio_nop $callback->()
…		…
268	IO::AIO::idle_timeout $seconds	283	IO::AIO::idle_timeout $seconds
269	IO::AIO::max_outstanding $maxreqs	284	IO::AIO::max_outstanding $maxreqs
270	IO::AIO::nreqs	285	IO::AIO::nreqs
271	IO::AIO::nready	286	IO::AIO::nready
272	IO::AIO::npending	287	IO::AIO::npending
		288	IO::AIO::reinit
		289
		290	$nfd = IO::AIO::get_fdlimit
		291	IO::AIO::min_fdlimit $nfd
273		292
274	IO::AIO::sendfile $ofh, $ifh, $offset, $count	293	IO::AIO::sendfile $ofh, $ifh, $offset, $count
275	IO::AIO::fadvise $fh, $offset, $len, $advice	294	IO::AIO::fadvise $fh, $offset, $len, $advice
		295	IO::AIO::fexecve $fh, $argv, $envp
		296
		297	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		298	IO::AIO::munmap $scalar
		299	IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
276	IO::AIO::madvise $scalar, $offset, $length, $advice	300	IO::AIO::madvise $scalar, $offset, $length, $advice
277	IO::AIO::mprotect $scalar, $offset, $length, $protect	301	IO::AIO::mprotect $scalar, $offset, $length, $protect
278	IO::AIO::munlock $scalar, $offset = 0, $length = undef	302	IO::AIO::munlock $scalar, $offset = 0, $length = undef
279	IO::AIO::munlockall	303	IO::AIO::munlockall
280		304
281	=head2 AIO REQUEST FUNCTIONS	305	# stat extensions
		306	$counter = IO::AIO::st_gen
		307	$seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		308	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		309	$nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		310	$seconds = IO::AIO::st_btimesec
		311	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		312
		313	# very much unportable syscalls
		314	IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
		315	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		316	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		317
		318	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		319	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		320
		321	$fh = IO::AIO::eventfd [$initval, [$flags]]
		322	$fh = IO::AIO::memfd_create $pathname[, $flags]
		323
		324	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		325	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		326	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		327
		328	$fh = IO::AIO::pidfd_open $pid[, $flags]
		329	$status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		330	$fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		331
		332	=head2 API NOTES
282		333
283	All the C<aio_*> calls are more or less thin wrappers around the syscall	334	All the C<aio_*> calls are more or less thin wrappers around the syscall
284	with the same name (sans C<aio_>). The arguments are similar or identical,	335	with the same name (sans C<aio_>). The arguments are similar or identical,
285	and they all accept an additional (and optional) C<$callback> argument	336	and they all accept an additional (and optional) C<$callback> argument
286	which must be a code reference. This code reference will get called with	337	which must be a code reference. This code reference will be called after
287	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	338	the syscall has been executed in an asynchronous fashion. The results
288	perl, which usually delivers "false") as its sole argument after the given	339	of the request will be passed as arguments to the callback (and, if an
289	syscall has been executed asynchronously.	340	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		341	most syscalls return C<-1> on error, unlike perl, which usually delivers
		342	"false").
		343
		344	Some requests (such as C<aio_readdir>) pass the actual results and
		345	communicate failures by passing C<undef>.
290		346
291	All functions expecting a filehandle keep a copy of the filehandle	347	All functions expecting a filehandle keep a copy of the filehandle
292	internally until the request has finished.	348	internally until the request has finished.
293		349
294	All functions return request objects of type L<IO::AIO::REQ> that allow	350	All functions return request objects of type L<IO::AIO::REQ> that allow
295	further manipulation of those requests while they are in-flight.	351	further manipulation of those requests while they are in-flight.
296		352
297	The pathnames you pass to these routines I<should> be absolute. The	353	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	354	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	355	current working directory could have changed. Alternatively, you can
300	sure that you never change the current working directory anywhere in	356	make sure that you never change the current working directory anywhere
301	the program and then use relative paths. Lastly, you can take advantage	357	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	358	of IO::AIOs working directory abstraction, that lets you specify paths
		359	relative to some previously-opened "working directory object" - see the
303	C<IO::AIO::WD> class later in this document.	360	description of the C<IO::AIO::WD> class later in this document.
304		361
305	To encode pathnames as octets, either make sure you either: a) always pass	362	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	363	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	364	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	365	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)	366	effect in the user environment, d) use Glib::filename_from_unicode on
310	use something else to ensure your scalar has the correct contents.	367	unicode filenames or e) use something else to ensure your scalar has the
		368	correct contents.
311		369
312	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	370	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
313	handles correctly whether it is set or not.	371	handles correctly whether it is set or not.
		372
		373	=head2 AIO REQUEST FUNCTIONS
314		374
315	=over 4	375	=over 4
316		376
317	=item $prev_pri = aioreq_pri [$pri]	377	=item $prev_pri = aioreq_pri [$pri]
318		378
…		…
348		408
349		409
350	=item aio_open $pathname, $flags, $mode, $callback->($fh)	410	=item aio_open $pathname, $flags, $mode, $callback->($fh)
351		411
352	Asynchronously open or create a file and call the callback with a newly	412	Asynchronously open or create a file and call the callback with a newly
353	created filehandle for the file.	413	created filehandle for the file (or C<undef> in case of an error).
354		414
355	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	415	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
356	for an explanation.	416	for an explanation.
357		417
358	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	418	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
381	following POSIX and non-POSIX constants are available (missing ones on	441	following POSIX and non-POSIX constants are available (missing ones on
382	your system are, as usual, C<0>):	442	your system are, as usual, C<0>):
383		443
384	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,	444	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
385	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,	445	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
386	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.	446	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
387		447
388		448
389	=item aio_close $fh, $callback->($status)	449	=item aio_close $fh, $callback->($status)
390		450
391	Asynchronously close a file and call the callback with the result	451	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	461	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.	462	free for reuse until the perl filehandle is closed.
403		463
404	=cut	464	=cut
405		465
		466	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		467
		468	Seeks the filehandle to the new C<$offset>, similarly to perl's
		469	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		470	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		471	C<IO::AIO::SEEK_END>).
		472
		473	The resulting absolute offset will be passed to the callback, or C<-1> in
		474	case of an error.
		475
		476	In theory, the C<$whence> constants could be different than the
		477	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		478	so don't panic.
		479
		480	As a GNU/Linux (and maybe Solaris) extension, also the constants
		481	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		482	could be found. No guarantees about suitability for use in C<aio_seek> or
		483	Perl's C<sysseek> can be made though, although I would naively assume they
		484	"just work".
		485
406	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	486	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
407		487
408	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	488	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
409		489
410	Reads or writes C<$length> bytes from or to the specified C<$fh> and	490	Reads or writes C<$length> bytes from or to the specified C<$fh> and
411	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	491	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
412	and calls the callback without the actual number of bytes read (or -1 on	492	calls the callback with the actual number of bytes transferred (or -1 on
413	error, just like the syscall).	493	error, just like the syscall).
414		494
415	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	495	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
416	offset plus the actual number of bytes read.	496	offset plus the actual number of bytes read.
417		497
…		…
475	As native sendfile syscalls (as practically any non-POSIX interface hacked	555	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	556	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	557	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,	558	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> -	559	so you really really should check the return value of C<aio_sendfile> -
480	fewre bytes than expected might have been transferred.	560	fewer bytes than expected might have been transferred.
481		561
482		562
483	=item aio_readahead $fh,$offset,$length, $callback->($retval)	563	=item aio_readahead $fh,$offset,$length, $callback->($retval)
484		564
485	C<aio_readahead> populates the page cache with data from a file so that	565	C<aio_readahead> populates the page cache with data from a file so that
…		…
489	whole pages, so that offset is effectively rounded down to a page boundary	569	whole pages, so that offset is effectively rounded down to a page boundary
490	and bytes are read up to the next page boundary greater than or equal to	570	and bytes are read up to the next page boundary greater than or equal to
491	(off-set+length). C<aio_readahead> does not read beyond the end of the	571	(off-set+length). C<aio_readahead> does not read beyond the end of the
492	file. The current file offset of the file is left unchanged.	572	file. The current file offset of the file is left unchanged.
493		573
494	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	574	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
495	emulated by simply reading the data, which would have a similar effect.	575	be emulated by simply reading the data, which would have a similar effect.
496		576
497		577
498	=item aio_stat $fh_or_path, $callback->($status)	578	=item aio_stat $fh_or_path, $callback->($status)
499		579
500	=item aio_lstat $fh, $callback->($status)	580	=item aio_lstat $fh, $callback->($status)
501		581
502	Works like perl's C<stat> or C<lstat> in void context. The callback will	582	Works almost exactly like perl's C<stat> or C<lstat> in void context. The
503	be called after the stat and the results will be available using C<stat _>	583	callback will be called after the stat and the results will be available
504	or C<-s _> etc...	584	using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
		585	and C<-T>).
505		586
506	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,	587	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
507	for an explanation.	588	for an explanation.
508		589
509	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	590	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
…		…
516	behaviour).	597	behaviour).
517		598
518	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,	599	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
519	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,	600	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
520	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.	601	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		602
		603	To access higher resolution stat timestamps, see L<SUBSECOND STAT TIME
		604	ACCESS>.
521		605
522	Example: Print the length of F</etc/passwd>:	606	Example: Print the length of F</etc/passwd>:
523		607
524	aio_stat "/etc/passwd", sub {	608	aio_stat "/etc/passwd", sub {
525	$_[0] and die "stat failed: $!";	609	$_[0] and die "stat failed: $!";
…		…
569	namemax => 255,	653	namemax => 255,
570	frsize => 1024,	654	frsize => 1024,
571	fsid => 1810	655	fsid => 1810
572	}	656	}
573		657
574
575	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	658	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
576		659
577	Works like perl's C<utime> function (including the special case of $atime	660	Works like perl's C<utime> function (including the special case of $atime
578	and $mtime being undef). Fractional times are supported if the underlying	661	and $mtime being undef). Fractional times are supported if the underlying
579	syscalls support them.	662	syscalls support them.
580		663
581	When called with a pathname, uses utimes(2) if available, otherwise	664	When called with a pathname, uses utimensat(2) or utimes(2) if available,
582	utime(2). If called on a file descriptor, uses futimes(2) if available,	665	otherwise utime(2). If called on a file descriptor, uses futimens(2)
583	otherwise returns ENOSYS, so this is not portable.	666	or futimes(2) if available, otherwise returns ENOSYS, so this is not
		667	portable.
584		668
585	Examples:	669	Examples:
586		670
587	# set atime and mtime to current time (basically touch(1)):	671	# set atime and mtime to current time (basically touch(1)):
588	aio_utime "path", undef, undef;	672	aio_utime "path", undef, undef;
…		…
606	=item aio_truncate $fh_or_path, $offset, $callback->($status)	690	=item aio_truncate $fh_or_path, $offset, $callback->($status)
607		691
608	Works like truncate(2) or ftruncate(2).	692	Works like truncate(2) or ftruncate(2).
609		693
610		694
		695	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		696
		697	Allocates or frees disk space according to the C<$mode> argument. See the
		698	linux C<fallocate> documentation for details.
		699
		700	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		701	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		702	to deallocate a file range.
		703
		704	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		705	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		706	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		707	to unshare shared blocks (see your L<fallocate(2)> manpage).
		708
		709	The file system block size used by C<fallocate> is presumably the
		710	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		711	can dictate other limitations.
		712
		713	If C<fallocate> isn't available or cannot be emulated (currently no
		714	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		715
		716
611	=item aio_chmod $fh_or_path, $mode, $callback->($status)	717	=item aio_chmod $fh_or_path, $mode, $callback->($status)
612		718
613	Works like perl's C<chmod> function.	719	Works like perl's C<chmod> function.
614		720
615		721
…		…
652		758
653		759
654	=item aio_realpath $pathname, $callback->($path)	760	=item aio_realpath $pathname, $callback->($path)
655		761
656	Asynchronously make the path absolute and resolve any symlinks in	762	Asynchronously make the path absolute and resolve any symlinks in
657	C<$path>. The resulting path only consists of directories (Same as	763	C<$path>. The resulting path only consists of directories (same as
658	L<Cwd::realpath>).	764	L<Cwd::realpath>).
659		765
660	This request can be used to get the absolute path of the current working	766	This request can be used to get the absolute path of the current working
661	directory by passing it a path of F<.> (a single dot).	767	directory by passing it a path of F<.> (a single dot).
662		768
663		769
664	=item aio_rename $srcpath, $dstpath, $callback->($status)	770	=item aio_rename $srcpath, $dstpath, $callback->($status)
665		771
666	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	772	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
667	rename(2) and call the callback with the result code.	773	rename(2) and call the callback with the result code.
		774
		775	On systems that support the AIO::WD working directory abstraction
		776	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		777	of failing, C<rename> is called on the absolute path of C<$wd>.
		778
		779
		780	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		781
		782	Basically a version of C<aio_rename> with an additional C<$flags>
		783	argument. Calling this with C<$flags=0> is the same as calling
		784	C<aio_rename>.
		785
		786	Non-zero flags are currently only supported on GNU/Linux systems that
		787	support renameat2. Other systems fail with C<ENOSYS> in this case.
		788
		789	The following constants are available (missing ones are, as usual C<0>),
		790	see renameat2(2) for details:
		791
		792	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		793	and C<IO::AIO::RENAME_WHITEOUT>.
668		794
669		795
670	=item aio_mkdir $pathname, $mode, $callback->($status)	796	=item aio_mkdir $pathname, $mode, $callback->($status)
671		797
672	Asynchronously mkdir (create) a directory and call the callback with	798	Asynchronously mkdir (create) a directory and call the callback with
…		…
677	=item aio_rmdir $pathname, $callback->($status)	803	=item aio_rmdir $pathname, $callback->($status)
678		804
679	Asynchronously rmdir (delete) a directory and call the callback with the	805	Asynchronously rmdir (delete) a directory and call the callback with the
680	result code.	806	result code.
681		807
		808	On systems that support the AIO::WD working directory abstraction
		809	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		810	C<rmdir> is called on the absolute path of C<$wd>.
		811
682		812
683	=item aio_readdir $pathname, $callback->($entries)	813	=item aio_readdir $pathname, $callback->($entries)
684		814
685	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	815	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
686	directory (i.e. opendir + readdir + closedir). The entries will not be	816	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
701		831
702	=over 4	832	=over 4
703		833
704	=item IO::AIO::READDIR_DENTS	834	=item IO::AIO::READDIR_DENTS
705		835
706	When this flag is off, then the callback gets an arrayref consisting of	836	Normally the callback gets an arrayref consisting of names only (as
707	names only (as with C<aio_readdir>), otherwise it gets an arrayref with	837	with C<aio_readdir>). If this flag is set, then the callback gets an
708	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	838	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
709	entry in more detail.	839	single directory entry in more detail:
710		840
711	C<$name> is the name of the entry.	841	C<$name> is the name of the entry.
712		842
713	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	843	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
714		844
715	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	845	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
716	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	846	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
717	C<IO::AIO::DT_WHT>.	847	C<IO::AIO::DT_WHT>.
718		848
719	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	849	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
720	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	850	to know, you have to run stat yourself. Also, for speed/memory reasons,
721	scalars are read-only: you can not modify them.	851	the C<$type> scalars are read-only: you must not modify them.
722		852
723	C<$inode> is the inode number (which might not be exact on systems with 64	853	C<$inode> is the inode number (which might not be exact on systems with 64
724	bit inode numbers and 32 bit perls). This field has unspecified content on	854	bit inode numbers and 32 bit perls). This field has unspecified content on
725	systems that do not deliver the inode information.	855	systems that do not deliver the inode information.
726		856
…		…
737	short names are tried first.	867	short names are tried first.
738		868
739	=item IO::AIO::READDIR_STAT_ORDER	869	=item IO::AIO::READDIR_STAT_ORDER
740		870
741	When this flag is set, then the names will be returned in an order	871	When this flag is set, then the names will be returned in an order
742	suitable for stat()'ing each one. That is, when you plan to stat()	872	suitable for stat()'ing each one. That is, when you plan to stat() most or
743	all files in the given directory, then the returned order will likely	873	all files in the given directory, then the returned order will likely be
744	be fastest.	874	faster.
745		875
746	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then	876	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
747	the likely dirs come first, resulting in a less optimal stat order.	877	then the likely dirs come first, resulting in a less optimal stat order
		878	for stat'ing all entries, but likely a more optimal order for finding
		879	subdirectories.
748		880
749	=item IO::AIO::READDIR_FOUND_UNKNOWN	881	=item IO::AIO::READDIR_FOUND_UNKNOWN
750		882
751	This flag should not be set when calling C<aio_readdirx>. Instead, it	883	This flag should not be set when calling C<aio_readdirx>. Instead, it
752	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	884	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
…		…
754	C<$type>'s are known, which can be used to speed up some algorithms.	886	C<$type>'s are known, which can be used to speed up some algorithms.
755		887
756	=back	888	=back
757		889
758		890
		891	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		892
		893	Opens, reads and closes the given file. The data is put into C<$data>,
		894	which is resized as required.
		895
		896	If C<$offset> is negative, then it is counted from the end of the file.
		897
		898	If C<$length> is zero, then the remaining length of the file is
		899	used. Also, in this case, the same limitations to modifying C<$data> apply
		900	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		901	with C<substr>. If the size of the file is known, specifying a non-zero
		902	C<$length> results in a performance advantage.
		903
		904	This request is similar to the older C<aio_load> request, but since it is
		905	a single request, it might be more efficient to use.
		906
		907	Example: load F</etc/passwd> into C<$passwd>.
		908
		909	my $passwd;
		910	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		911	$_[0] >= 0
		912	or die "/etc/passwd: $!\n";
		913
		914	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		915	print $passwd;
		916	};
		917	IO::AIO::flush;
		918
		919
759	=item aio_load $pathname, $data, $callback->($status)	920	=item aio_load $pathname, $data, $callback->($status)
760		921
761	This is a composite request that tries to fully load the given file into	922	This is a composite request that tries to fully load the given file into
762	memory. Status is the same as with aio_read.	923	memory. Status is the same as with aio_read.
		924
		925	Using C<aio_slurp> might be more efficient, as it is a single request.
763		926
764	=cut	927	=cut
765		928
766	sub aio_load($$;$) {	929	sub aio_load($$;$) {
767	my ($path, undef, $cb) = @_;	930	my ($path, undef, $cb) = @_;
…		…
787	=item aio_copy $srcpath, $dstpath, $callback->($status)	950	=item aio_copy $srcpath, $dstpath, $callback->($status)
788		951
789	Try to copy the I<file> (directories not supported as either source or	952	Try to copy the I<file> (directories not supported as either source or
790	destination) from C<$srcpath> to C<$dstpath> and call the callback with	953	destination) from C<$srcpath> to C<$dstpath> and call the callback with
791	a status of C<0> (ok) or C<-1> (error, see C<$!>).	954	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		955
		956	Existing destination files will be truncated.
792		957
793	This is a composite request that creates the destination file with	958	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	959	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	960	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
796	uid/gid, in that order.	961	uid/gid, in that order.
…		…
906	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1071	Scans a directory (similar to C<aio_readdir>) but additionally tries to
907	efficiently separate the entries of directory C<$path> into two sets of	1072	efficiently separate the entries of directory C<$path> into two sets of
908	names, directories you can recurse into (directories), and ones you cannot	1073	names, directories you can recurse into (directories), and ones you cannot
909	recurse into (everything else, including symlinks to directories).	1074	recurse into (everything else, including symlinks to directories).
910		1075
911	C<aio_scandir> is a composite request that creates of many sub requests_	1076	C<aio_scandir> is a composite request that generates many sub requests.
912	C<$maxreq> specifies the maximum number of outstanding aio requests that	1077	C<$maxreq> specifies the maximum number of outstanding aio requests that
913	this function generates. If it is C<< <= 0 >>, then a suitable default	1078	this function generates. If it is C<< <= 0 >>, then a suitable default
914	will be chosen (currently 4).	1079	will be chosen (currently 4).
915		1080
916	On error, the callback is called without arguments, otherwise it receives	1081	On error, the callback is called without arguments, otherwise it receives
…		…
966		1131
967	my $grp = aio_group $cb;	1132	my $grp = aio_group $cb;
968		1133
969	$maxreq = 4 if $maxreq <= 0;	1134	$maxreq = 4 if $maxreq <= 0;
970		1135
971	# stat once	1136	# get a wd object
972	aioreq_pri $pri;	1137	aioreq_pri $pri;
973	add $grp aio_stat $path, sub {	1138	add $grp aio_wd $path, sub {
		1139	$_[0]
974	return $grp->result () if $_[0];	1140	or return $grp->result ();
975	my $now = time;
976	my $hash1 = join ":", (stat _)[0,1,3,7,9];
977		1141
978	# read the directory entries	1142	my $wd = [shift, "."];
		1143
		1144	# stat once
979	aioreq_pri $pri;	1145	aioreq_pri $pri;
980	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1146	add $grp aio_stat $wd, sub {
981	my $entries = shift
982	or return $grp->result ();	1147	return $grp->result () if $_[0];
		1148	my $now = time;
		1149	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		1150	my $rdxflags = READDIR_DIRS_FIRST;
983		1151
984	# stat the dir another time	1152	if ((stat _)[3] < 2) {
		1153	# at least one non-POSIX filesystem exists
		1154	# that returns useful DT_type values: btrfs,
		1155	# so optimise for this here by requesting dents
		1156	$rdxflags |= READDIR_DENTS;
		1157	}
		1158
		1159	# read the directory entries
985	aioreq_pri $pri;	1160	aioreq_pri $pri;
986	add $grp aio_stat $path, sub {	1161	add $grp aio_readdirx $wd, $rdxflags, sub {
987	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1162	my ($entries, $flags) = @_
		1163	or return $grp->result ();
988		1164
		1165	if ($rdxflags & READDIR_DENTS) {
		1166	# if we requested type values, see if we can use them directly.
		1167
		1168	# if there were any DT_UNKNOWN entries then we assume we
		1169	# don't know. alternatively, we could assume that if we get
		1170	# one DT_DIR, then all directories are indeed marked with
		1171	# DT_DIR, but this seems not required for btrfs, and this
		1172	# is basically the "btrfs can't get it's act together" code
		1173	# branch.
		1174	unless ($flags & READDIR_FOUND_UNKNOWN) {
		1175	# now we have valid DT_ information for all entries,
		1176	# so use it as an optimisation without further stat's.
		1177	# they must also all be at the beginning of @$entries
		1178	# by now.
		1179
989	my $ndirs;	1180	my $dirs;
990		1181
991	# take the slow route if anything looks fishy
992	if ($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) {	1182	if (@$entries) {
1015	push @nondirs, $entry;	1183	for (0 .. $#$entries) {
1016	} else {	1184	if ($entries->[$_][1] != DT_DIR) {
1017	# need to check for real directory	1185	# splice out directories
1018	aioreq_pri $pri;	1186	$dirs = [splice @$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	}	1187	last;
1027	} else {
1028	push @nondirs, $entry;
1029	}	1188	}
1030	}	1189	}
		1190
		1191	# if we didn't find any non-dir, then all entries are dirs
		1192	unless ($dirs) {
		1193	($dirs, $entries) = ($entries, []);
		1194	}
		1195	} else {
		1196	# directory is empty, so there are no sbdirs
		1197	$dirs = [];
1031	}	1198	}
		1199
		1200	# either splice'd the directories out or the dir was empty.
		1201	# convert dents to filenames
		1202	$_ = $_->[0] for @$dirs;
		1203	$_ = $_->[0] for @$entries;
		1204
		1205	return $grp->result ($dirs, $entries);
		1206	}
		1207
		1208	# cannot use, so return to our old ways
		1209	# by pretending we only scanned for names.
		1210	$_ = $_->[0] for @$entries;
		1211	}
		1212
		1213	# stat the dir another time
		1214	aioreq_pri $pri;
		1215	add $grp aio_stat $wd, sub {
		1216	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		1217
		1218	my $ndirs;
		1219
		1220	# take the slow route if anything looks fishy
		1221	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
		1222	$ndirs = -1;
		1223	} else {
		1224	# if nlink == 2, we are finished
		1225	# for non-posix-fs's, we rely on nlink < 2
		1226	$ndirs = (stat _)[3] - 2
		1227	or return $grp->result ([], $entries);
		1228	}
		1229
		1230	my (@dirs, @nondirs);
		1231
		1232	my $statgrp = add $grp aio_group sub {
		1233	$grp->result (\@dirs, \@nondirs);
		1234	};
		1235
		1236	limit $statgrp $maxreq;
		1237	feed $statgrp sub {
		1238	return unless @$entries;
		1239	my $entry = shift @$entries;
		1240
		1241	aioreq_pri $pri;
		1242	$wd->[1] = "$entry/.";
		1243	add $statgrp aio_stat $wd, sub {
		1244	if ($_[0] < 0) {
		1245	push @nondirs, $entry;
		1246	} else {
		1247	# need to check for real directory
		1248	aioreq_pri $pri;
		1249	$wd->[1] = $entry;
		1250	add $statgrp aio_lstat $wd, sub {
		1251	if (-d _) {
		1252	push @dirs, $entry;
		1253
		1254	unless (--$ndirs) {
		1255	push @nondirs, @$entries;
		1256	feed $statgrp;
		1257	}
		1258	} else {
		1259	push @nondirs, $entry;
		1260	}
		1261	}
		1262	}
		1263	};
1032	};	1264	};
1033	};	1265	};
1034	};	1266	};
1035	};	1267	};
1036	};	1268	};
…		…
1039	}	1271	}
1040		1272
1041	=item aio_rmtree $pathname, $callback->($status)	1273	=item aio_rmtree $pathname, $callback->($status)
1042		1274
1043	Delete a directory tree starting (and including) C<$path>, return the	1275	Delete a directory tree starting (and including) C<$path>, return the
1044	status of the final C<rmdir> only. This is a composite request that	1276	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	1277	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1046	everything else.	1278	everything else.
1047		1279
1048	=cut	1280	=cut
1049		1281
…		…
1070	add $grp $dirgrp;	1302	add $grp $dirgrp;
1071	};	1303	};
1072		1304
1073	$grp	1305	$grp
1074	}	1306	}
		1307
		1308	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1309
		1310	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1311
		1312	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1313	they execute asynchronously and pass the return value to the callback.
		1314
		1315	Both calls can be used for a lot of things, some of which make more sense
		1316	to run asynchronously in their own thread, while some others make less
		1317	sense. For example, calls that block waiting for external events, such
		1318	as locking, will also lock down an I/O thread while it is waiting, which
		1319	can deadlock the whole I/O system. At the same time, there might be no
		1320	alternative to using a thread to wait.
		1321
		1322	So in general, you should only use these calls for things that do
		1323	(filesystem) I/O, not for things that wait for other events (network,
		1324	other processes), although if you are careful and know what you are doing,
		1325	you still can.
		1326
		1327	The following constants are available and can be used for normal C<ioctl>
		1328	and C<fcntl> as well (missing ones are, as usual C<0>):
		1329
		1330	C<F_DUPFD_CLOEXEC>,
		1331
		1332	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1333
		1334	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1335
		1336	C<F_ADD_SEALS>, C<F_GET_SEALS>, C<F_SEAL_SEAL>, C<F_SEAL_SHRINK>, C<F_SEAL_GROW> and
		1337	C<F_SEAL_WRITE>.
		1338
		1339	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1340	C<FS_IOC_FIEMAP>.
		1341
		1342	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1343	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1344
		1345	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1346	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1347	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1348	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1349	C<FS_FL_USER_MODIFIABLE>.
		1350
		1351	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1352	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1353	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1354	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
1075		1355
1076	=item aio_sync $callback->($status)	1356	=item aio_sync $callback->($status)
1077		1357
1078	Asynchronously call sync and call the callback when finished.	1358	Asynchronously call sync and call the callback when finished.
1079		1359
…		…
1148	};	1428	};
1149		1429
1150	$grp	1430	$grp
1151	}	1431	}
1152		1432
1153	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1433	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1154		1434
1155	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1435	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1156	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1436	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1157	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1437	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1158	scalar must only be modified in-place while an aio operation is pending on	1438	scalar must only be modified in-place while an aio operation is pending on
…		…
1160		1440
1161	It calls the C<msync> function of your OS, if available, with the memory	1441	It calls the C<msync> function of your OS, if available, with the memory
1162	area starting at C<$offset> in the string and ending C<$length> bytes	1442	area starting at C<$offset> in the string and ending C<$length> bytes
1163	later. If C<$length> is negative, counts from the end, and if C<$length>	1443	later. If C<$length> is negative, counts from the end, and if C<$length>
1164	is C<undef>, then it goes till the end of the string. The flags can be	1444	is C<undef>, then it goes till the end of the string. The flags can be
1165	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1445	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1166	C<IO::AIO::MS_SYNC>.	1446	C<IO::AIO::MS_INVALIDATE>.
1167		1447
1168	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1448	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1169		1449
1170	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1450	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1171	scalars.	1451	scalars.
1172		1452
1173	It touches (reads or writes) all memory pages in the specified	1453	It touches (reads or writes) all memory pages in the specified
1174	range inside the scalar. All caveats and parameters are the same	1454	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	1455	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	1456	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	1457	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1178	writing an octet from it, which dirties the page).	1458	writing an octet from it, which dirties the page).
1179		1459
1180	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1460	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1181		1461
1182	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1462	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1201	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;	1481	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1202	aio_mlock $data; # mlock in background	1482	aio_mlock $data; # mlock in background
1203		1483
1204	=item aio_mlockall $flags, $callback->($status)	1484	=item aio_mlockall $flags, $callback->($status)
1205		1485
1206	Calls the C<mlockall> function with the given C<$flags> (a combination of	1486	Calls the C<mlockall> function with the given C<$flags> (a
1207	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).	1487	combination of C<IO::AIO::MCL_CURRENT>, C<IO::AIO::MCL_FUTURE> and
		1488	C<IO::AIO::MCL_ONFAULT>).
1208		1489
1209	On systems that do not implement C<mlockall>, this function returns C<-1>	1490	On systems that do not implement C<mlockall>, this function returns C<-1>
1210	and sets errno to C<ENOSYS>.	1491	and sets errno to C<ENOSYS>. Similarly, flag combinations not supported
		1492	by the system result in a return value of C<-1> with errno being set to
		1493	C<EINVAL>.
1211		1494
1212	Note that the corresponding C<munlockall> is synchronous and is	1495	Note that the corresponding C<munlockall> is synchronous and is
1213	documented under L<MISCELLANEOUS FUNCTIONS>.	1496	documented under L<MISCELLANEOUS FUNCTIONS>.
1214		1497
1215	Example: asynchronously lock all current and future pages into memory.	1498	Example: asynchronously lock all current and future pages into memory.
1216		1499
1217	aio_mlockall IO::AIO::MCL_FUTURE;	1500	aio_mlockall IO::AIO::MCL_FUTURE;
		1501
		1502	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1503
		1504	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1505	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1506	the ioctl is not available on your OS, then this request will fail with
		1507	C<ENOSYS>.
		1508
		1509	C<$start> is the starting offset to query extents for, C<$length> is the
		1510	size of the range to query - if it is C<undef>, then the whole file will
		1511	be queried.
		1512
		1513	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1514	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1515	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1516	the data portion.
		1517
		1518	C<$count> is the maximum number of extent records to return. If it is
		1519	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1520	case, if it is C<0>, then the callback receives the number of extents
		1521	instead of the extents themselves (which is unreliable, see below).
		1522
		1523	If an error occurs, the callback receives no arguments. The special
		1524	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1525
		1526	Otherwise, the callback receives an array reference with extent
		1527	structures. Each extent structure is an array reference itself, with the
		1528	following members:
		1529
		1530	[$logical, $physical, $length, $flags]
		1531
		1532	Flags is any combination of the following flag values (typically either C<0>
		1533	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1534
		1535	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1536	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1537	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1538	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1539	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1540	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1541
		1542	At the time of this writing (Linux 3.2), this request is unreliable unless
		1543	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1544	it to return all extents of a range for files with a large number of
		1545	extents. The code (only) works around all these issues if C<$count> is
		1546	C<undef>.
1218		1547
1219	=item aio_group $callback->(...)	1548	=item aio_group $callback->(...)
1220		1549
1221	This is a very special aio request: Instead of doing something, it is a	1550	This is a very special aio request: Instead of doing something, it is a
1222	container for other aio requests, which is useful if you want to bundle	1551	container for other aio requests, which is useful if you want to bundle
…		…
1286	object. This object stores the canonicalised, absolute version of the	1615	object. This object stores the canonicalised, absolute version of the
1287	path, and on systems that allow it, also a directory file descriptor.	1616	path, and on systems that allow it, also a directory file descriptor.
1288		1617
1289	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>	1618	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
1290	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD	1619	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
1291	object and a pathname instead. If the pathname is absolute, the	1620	object and a pathname instead (or the IO::AIO::WD object alone, which
		1621	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
1292	IO::AIO::WD objetc is ignored, otherwise the pathname is resolved relative	1622	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
1293	to that IO::AIO::WD object.	1623	to that IO::AIO::WD object.
1294		1624
1295	For example, to get a wd object for F</etc> and then stat F<passwd>	1625	For example, to get a wd object for F</etc> and then stat F<passwd>
1296	inside, you would write:	1626	inside, you would write:
1297		1627
…		…
1305	aio_stat [$etcdir, "passwd"], sub {	1635	aio_stat [$etcdir, "passwd"], sub {
1306	# yay	1636	# yay
1307	};	1637	};
1308	};	1638	};
1309		1639
		1640	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	1641	creating an IO::AIO::WD object is itself a potentially blocking operation,
1311	blocking operation, which is why it is done asynchronously.	1642	which is why it is done asynchronously.
		1643
		1644	To stat the directory obtained with C<aio_wd> above, one could write
		1645	either of the following three request calls:
		1646
		1647	aio_lstat "/etc" , sub { ... # pathname as normal string
		1648	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1649	aio_lstat $wd , sub { ... # shorthand for the previous
1312		1650
1313	As with normal pathnames, IO::AIO keeps a copy of the working directory	1651	As with normal pathnames, IO::AIO keeps a copy of the working directory
1314	object and the pathname string, so you could write the following without	1652	object and the pathname string, so you could write the following without
1315	causing any issues due to C<$path> getting reused:	1653	causing any issues due to C<$path> getting reused:
1316		1654
…		…
1326	There are some caveats: when directories get renamed (or deleted), the	1664	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	1665	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,	1666	nowhere at all), while the directory fd, if available on the system,
1329	will still point to the original directory. Most functions accepting a	1667	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	1668	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	1669	older systems. Some functions (such as C<aio_realpath>) will always rely on
1332	string form of the pathname.	1670	the string form of the pathname.
1333		1671
1334	So this fucntionality is mainly useful to get some protection against	1672	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	1673	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	1674	reference, and to speed up doing many operations in the same directory
1337	(e.g. when stat'ing all files in a directory).	1675	(e.g. when stat'ing all files in a directory).
1338		1676
1339	The following functions implement this working directory abstraction:	1677	The following functions implement this working directory abstraction:
…		…
1352	passing C<undef> as working directory component of a pathname fails the	1690	passing C<undef> as working directory component of a pathname fails the
1353	request with C<ENOENT>, there is often no need for error checking in the	1691	request with C<ENOENT>, there is often no need for error checking in the
1354	C<aio_wd> callback, as future requests using the value will fail in the	1692	C<aio_wd> callback, as future requests using the value will fail in the
1355	expected way.	1693	expected way.
1356		1694
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	1695	=item IO::AIO::CWD
1361		1696
1362	This is a compiletime constant (object) that represents the process	1697	This is a compile time constant (object) that represents the process
1363	current working directory.	1698	current working directory.
1364		1699
1365	Specifying this object as working directory object for a pathname is as	1700	Specifying this object as working directory object for a pathname is as if
1366	if the pathname would be specified directly, without a directory object,	1701	the pathname would be specified directly, without a directory object. For
1367	e.g., these calls are functionally identical:	1702	example, these calls are functionally identical:
1368		1703
1369	aio_stat "somefile", sub { ... };	1704	aio_stat "somefile", sub { ... };
1370	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };	1705	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1371		1706
1372	=back	1707	=back
1373		1708
		1709	To recover the path associated with an IO::AIO::WD object, you can use
		1710	C<aio_realpath>:
		1711
		1712	aio_realpath $wd, sub {
		1713	warn "path is $_[0]\n";
		1714	};
		1715
		1716	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1717	sometimes, fall back to using an absolue path.
1374		1718
1375	=head2 IO::AIO::REQ CLASS	1719	=head2 IO::AIO::REQ CLASS
1376		1720
1377	All non-aggregate C<aio_*> functions return an object of this class when	1721	All non-aggregate C<aio_*> functions return an object of this class when
1378	called in non-void context.	1722	called in non-void context.
…		…
1496		1840
1497	Sets a feeder/generator on this group: every group can have an attached	1841	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,	1842	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,	1843	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,	1844	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,	1845	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1502	delaying any later requests for a long time.	1846	requests, delaying any later requests for a long time.
1503		1847
1504	To avoid this, and allow incremental generation of requests, you can	1848	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	1849	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>,	1850	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	1851	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	1883	The default value for the limit is C<0>, but note that setting a feeder
1540	automatically bumps it up to C<2>.	1884	automatically bumps it up to C<2>.
1541		1885
1542	=back	1886	=back
1543		1887
		1888
1544	=head2 SUPPORT FUNCTIONS	1889	=head2 SUPPORT FUNCTIONS
1545		1890
1546	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1891	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1547		1892
1548	=over 4	1893	=over 4
…		…
1556		1901
1557	See C<poll_cb> for an example.	1902	See C<poll_cb> for an example.
1558		1903
1559	=item IO::AIO::poll_cb	1904	=item IO::AIO::poll_cb
1560		1905
1561	Process some outstanding events on the result pipe. You have to call	1906	Process some requests that have reached the result phase (i.e. they have
		1907	been executed but the results are not yet reported). You have to call
		1908	this "regularly" to finish outstanding requests.
		1909
1562	this regularly. Returns C<0> if all events could be processed (or there	1910	Returns C<0> if all events could be processed (or there were no
1563	were no events to process), or C<-1> if it returned earlier for whatever	1911	events to process), or C<-1> if it returned earlier for whatever
1564	reason. Returns immediately when no events are outstanding. The amount of	1912	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	1913	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1566	C<IO::AIO::max_poll_time>.	1914	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1567		1915
1568	If not all requests were processed for whatever reason, the filehandle	1916	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	1917	descriptor will still be ready when C<poll_cb> returns, so normally you
1570	do anything special to have it called later.	1918	don't have to do anything special to have it called later.
1571		1919
1572	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1920	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1573	ready, it can be beneficial to call this function from loops which submit	1921	ready, it can be beneficial to call this function from loops which submit
1574	a lot of requests, to make sure the results get processed when they become	1922	a lot of requests, to make sure the results get processed when they become
1575	available and not just when the loop is finished and the event loop takes	1923	available and not just when the loop is finished and the event loop takes
…		…
1584	poll => 'r', async => 1,	1932	poll => 'r', async => 1,
1585	cb => \&IO::AIO::poll_cb);	1933	cb => \&IO::AIO::poll_cb);
1586		1934
1587	=item IO::AIO::poll_wait	1935	=item IO::AIO::poll_wait
1588		1936
1589	If there are any outstanding requests and none of them in the result	1937	Wait until either at least one request is in the result phase or no
1590	phase, wait till the result filehandle becomes ready for reading (simply	1938	requests are outstanding anymore.
1591	does a C<select> on the filehandle. This is useful if you want to	1939
1592	synchronously wait for some requests to finish).	1940	This is useful if you want to synchronously wait for some requests to
		1941	become ready, without actually handling them.
1593		1942
1594	See C<nreqs> for an example.	1943	See C<nreqs> for an example.
1595		1944
1596	=item IO::AIO::poll	1945	=item IO::AIO::poll
1597		1946
…		…
1608		1957
1609	Strictly equivalent to:	1958	Strictly equivalent to:
1610		1959
1611	IO::AIO::poll_wait, IO::AIO::poll_cb	1960	IO::AIO::poll_wait, IO::AIO::poll_cb
1612	while IO::AIO::nreqs;	1961	while IO::AIO::nreqs;
		1962
		1963	This function can be useful at program aborts, to make sure outstanding
		1964	I/O has been done (C<IO::AIO> uses an C<END> block which already calls
		1965	this function on normal exits), or when you are merely using C<IO::AIO>
		1966	for its more advanced functions, rather than for async I/O, e.g.:
		1967
		1968	my ($dirs, $nondirs);
		1969	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1970	IO::AIO::flush;
		1971	# $dirs, $nondirs are now set
1613		1972
1614	=item IO::AIO::max_poll_reqs $nreqs	1973	=item IO::AIO::max_poll_reqs $nreqs
1615		1974
1616	=item IO::AIO::max_poll_time $seconds	1975	=item IO::AIO::max_poll_time $seconds
1617		1976
…		…
1644	poll => 'r', nice => 1,	2003	poll => 'r', nice => 1,
1645	cb => &IO::AIO::poll_cb);	2004	cb => &IO::AIO::poll_cb);
1646		2005
1647	=back	2006	=back
1648		2007
		2008
1649	=head3 CONTROLLING THE NUMBER OF THREADS	2009	=head3 CONTROLLING THE NUMBER OF THREADS
1650		2010
1651	=over	2011	=over
1652		2012
1653	=item IO::AIO::min_parallel $nthreads	2013	=item IO::AIO::min_parallel $nthreads
…		…
1714	longer exceeded.	2074	longer exceeded.
1715		2075
1716	In other words, this setting does not enforce a queue limit, but can be	2076	In other words, this setting does not enforce a queue limit, but can be
1717	used to make poll functions block if the limit is exceeded.	2077	used to make poll functions block if the limit is exceeded.
1718		2078
1719	This is a very bad function to use in interactive programs because it	2079	This is a bad function to use in interactive programs because it blocks,
1720	blocks, and a bad way to reduce concurrency because it is inexact: Better	2080	and a bad way to reduce concurrency because it is inexact. If you need to
		2081	issue many requests without being able to call a poll function on demand,
1721	use an C<aio_group> together with a feed callback.	2082	it is better to use an C<aio_group> together with a feed callback.
1722		2083
1723	It's main use is in scripts without an event loop - when you want to stat	2084	Its main use is in scripts without an event loop - when you want to stat a
1724	a lot of files, you can write somehting like this:	2085	lot of files, you can write something like this:
1725		2086
1726	IO::AIO::max_outstanding 32;	2087	IO::AIO::max_outstanding 32;
1727		2088
1728	for my $path (...) {	2089	for my $path (...) {
1729	aio_stat $path , ...;	2090	aio_stat $path , ...;
1730	IO::AIO::poll_cb;	2091	IO::AIO::poll_cb;
1731	}	2092	}
1732		2093
1733	IO::AIO::flush;	2094	IO::AIO::flush;
1734		2095
1735	The call to C<poll_cb> inside the loop will normally return instantly, but	2096	The call to C<poll_cb> inside the loop will normally return instantly,
1736	as soon as more thna C<32> reqeusts are in-flight, it will block until	2097	allowing the loop to progress, but as soon as more than C<32> requests
1737	some requests have been handled. This keeps the loop from pushing a large	2098	are in-flight, it will block until some requests have been handled. This
1738	number of C<aio_stat> requests onto the queue.	2099	keeps the loop from pushing a large number of C<aio_stat> requests onto
		2100	the queue (which, with many paths to stat, can use up a lot of memory).
1739		2101
1740	The default value for C<max_outstanding> is very large, so there is no	2102	The default value for C<max_outstanding> is very large, so there is no
1741	practical limit on the number of outstanding requests.	2103	practical limit on the number of outstanding requests.
1742		2104
1743	=back	2105	=back
1744		2106
		2107
1745	=head3 STATISTICAL INFORMATION	2108	=head3 STATISTICAL INFORMATION
1746		2109
1747	=over	2110	=over
1748		2111
1749	=item IO::AIO::nreqs	2112	=item IO::AIO::nreqs
…		…
1766	Returns the number of requests currently in the pending state (executed,	2129	Returns the number of requests currently in the pending state (executed,
1767	but not yet processed by poll_cb).	2130	but not yet processed by poll_cb).
1768		2131
1769	=back	2132	=back
1770		2133
		2134
		2135	=head3 SUBSECOND STAT TIME ACCESS
		2136
		2137	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2138	generally find access/modification and change times with subsecond time
		2139	accuracy of the system supports it, but perl's built-in functions only
		2140	return the integer part.
		2141
		2142	The following functions return the timestamps of the most recent
		2143	stat with subsecond precision on most systems and work both after
		2144	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2145	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2146	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2147
		2148	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2149	full resolution without rounding and work with standard perl C<stat>,
		2150	alleviating the need to call the special C<Time::HiRes> functions, which
		2151	do not act like their perl counterparts.
		2152
		2153	On operating systems or file systems where subsecond time resolution is
		2154	not supported or could not be detected, a fractional part of C<0> is
		2155	returned, so it is always safe to call these functions.
		2156
		2157	=over 4
		2158
		2159	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		2160
		2161	Return the access, modication, change or birth time, respectively,
		2162	including fractional part. Due to the limited precision of floating point,
		2163	the accuracy on most platforms is only a bit better than milliseconds
		2164	for times around now - see the I<nsec> function family, below, for full
		2165	accuracy.
		2166
		2167	File birth time is only available when the OS and perl support it (on
		2168	FreeBSD and NetBSD at the time of this writing, although support is
		2169	adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
		2170	it). On systems where it isn't available, C<0> is currently returned, but
		2171	this might change to C<undef> in a future version.
		2172
		2173	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		2174
		2175	Returns access, modification, change and birth time all in one go, and
		2176	maybe more times in the future version.
		2177
		2178	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		2179
		2180	Return the fractional access, modifcation, change or birth time, in nanoseconds,
		2181	as an integer in the range C<0> to C<999999999>.
		2182
		2183	Note that no accessors are provided for access, modification and
		2184	change times - you need to get those from C<stat _> if required (C<int
		2185	IO::AIO::st_atime> and so on will I<not> generally give you the correct
		2186	value).
		2187
		2188	=item $seconds = IO::AIO::st_btimesec
		2189
		2190	The (integral) seconds part of the file birth time, if available.
		2191
		2192	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		2193
		2194	Like the functions above, but returns all four times in one go (and maybe
		2195	more in future versions).
		2196
		2197	=item $counter = IO::AIO::st_gen
		2198
		2199	Returns the generation counter (in practice this is just a random number)
		2200	of the file. This is only available on platforms which have this member in
		2201	their C<struct stat> (most BSDs at the time of this writing) and generally
		2202	only to the root usert. If unsupported, C<0> is returned, but this might
		2203	change to C<undef> in a future version.
		2204
		2205	=back
		2206
		2207	Example: print the high resolution modification time of F</etc>, using
		2208	C<stat>, and C<IO::AIO::aio_stat>.
		2209
		2210	if (stat "/etc") {
		2211	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2212	}
		2213
		2214	IO::AIO::aio_stat "/etc", sub {
		2215	$_[0]
		2216	and return;
		2217
		2218	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2219	};
		2220
		2221	IO::AIO::flush;
		2222
		2223	Output of the awbove on my system, showing reduced and full accuracy:
		2224
		2225	stat(/etc) mtime: 1534043702.020808
		2226	aio_stat(/etc) mtime: 1534043702.020807792
		2227
		2228
1771	=head3 MISCELLANEOUS FUNCTIONS	2229	=head3 MISCELLANEOUS FUNCTIONS
1772		2230
1773	IO::AIO implements some functions that might be useful, but are not	2231	IO::AIO implements some functions that are useful when you want to use
1774	asynchronous.	2232	some "Advanced I/O" function not available to in Perl, without going the
		2233	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2234	counterpart.
1775		2235
1776	=over 4	2236	=over 4
		2237
		2238	=item $retval = IO::AIO::fexecve $fh, $argv, $envp
		2239
		2240	A more-or-less direct equivalent to the POSIX C<fexecve> functions, which
		2241	allows you to specify the program to be executed via a file descriptor (or
		2242	handle). Returns C<-1> and sets errno to C<ENOSYS> if not available.
		2243
		2244	=item $numfd = IO::AIO::get_fdlimit
		2245
		2246	Tries to find the current file descriptor limit and returns it, or
		2247	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2248	the highest valid file descriptor number.
		2249
		2250	=item IO::AIO::min_fdlimit [$numfd]
		2251
		2252	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2253	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2254	is missing, it will try to set a very high limit, although this is not
		2255	recommended when you know the actual minimum that you require.
		2256
		2257	If the limit cannot be raised enough, the function makes a best-effort
		2258	attempt to increase the limit as much as possible, using various
		2259	tricks, while still failing. You can query the resulting limit using
		2260	C<IO::AIO::get_fdlimit>.
		2261
		2262	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2263	true.
1777		2264
1778	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2265	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1779		2266
1780	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2267	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1781	but is blocking (this makes most sense if you know the input data is	2268	but is blocking (this makes most sense if you know the input data is
…		…
1798	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2285	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1799		2286
1800	Simply calls the C<posix_madvise> function (see its	2287	Simply calls the C<posix_madvise> function (see its
1801	manpage for details). The following advice constants are	2288	manpage for details). The following advice constants are
1802	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2289	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1803	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2290	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2291	C<IO::AIO::MADV_DONTNEED>.
		2292
		2293	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2294	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2295	will be reduced to fit into the C<$scalar>.
1804		2296
1805	On systems that do not implement C<posix_madvise>, this function returns	2297	On systems that do not implement C<posix_madvise>, this function returns
1806	ENOSYS, otherwise the return value of C<posix_madvise>.	2298	ENOSYS, otherwise the return value of C<posix_madvise>.
1807		2299
1808	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2300	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
…		…
1810	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2302	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1811	$scalar (see its manpage for details). The following protect	2303	$scalar (see its manpage for details). The following protect
1812	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2304	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1813	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2305	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
1814		2306
		2307	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2308	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2309	will be reduced to fit into the C<$scalar>.
		2310
1815	On systems that do not implement C<mprotect>, this function returns	2311	On systems that do not implement C<mprotect>, this function returns
1816	ENOSYS, otherwise the return value of C<mprotect>.	2312	ENOSYS, otherwise the return value of C<mprotect>.
1817		2313
1818	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2314	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1819		2315
1820	Memory-maps a file (or anonymous memory range) and attaches it to the	2316	Memory-maps a file (or anonymous memory range) and attaches it to the
1821	given C<$scalar>, which will act like a string scalar.	2317	given C<$scalar>, which will act like a string scalar. Returns true on
		2318	success, and false otherwise.
1822		2319
		2320	The scalar must exist, but its contents do not matter - this means you
		2321	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2322	the scalar first.
		2323
1823	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2324	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1824	change the string length, and most read-only operations such as copying it	2325	which don't change the string length, and most read-only operations such
1825	or searching it with regexes and so on.	2326	as copying it or searching it with regexes and so on.
1826		2327
1827	Anything else is unsafe and will, at best, result in memory leaks.	2328	Anything else is unsafe and will, at best, result in memory leaks.
1828		2329
1829	The memory map associated with the C<$scalar> is automatically removed	2330	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	2331	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1831	C<IO::AIO::munmap> functions are called.	2332	or C<IO::AIO::munmap> functions are called on it.
1832		2333
1833	This calls the C<mmap>(2) function internally. See your system's manual	2334	This calls the C<mmap>(2) function internally. See your system's manual
1834	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2335	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1835		2336
1836	The C<$length> must be larger than zero and smaller than the actual	2337	The C<$length> must be larger than zero and smaller than the actual
1837	filesize.	2338	filesize.
1838		2339
1839	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2340	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1840	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2341	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1841		2342
1842	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2343	C<$flags> can be a combination of
1843	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2344	C<IO::AIO::MAP_SHARED> or
1844	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2345	C<IO::AIO::MAP_PRIVATE>,
		2346	or a number of system-specific flags (when not available, the are C<0>):
1845	(which is set to C<MAP_ANON> if your system only provides this	2347	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1846	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2348	C<IO::AIO::MAP_LOCKED>,
1847	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2349	C<IO::AIO::MAP_NORESERVE>,
		2350	C<IO::AIO::MAP_POPULATE>,
1848	C<IO::AIO::MAP_NONBLOCK>	2351	C<IO::AIO::MAP_NONBLOCK>,
		2352	C<IO::AIO::MAP_FIXED>,
		2353	C<IO::AIO::MAP_GROWSDOWN>,
		2354	C<IO::AIO::MAP_32BIT>,
		2355	C<IO::AIO::MAP_HUGETLB>,
		2356	C<IO::AIO::MAP_STACK>,
		2357	C<IO::AIO::MAP_FIXED_NOREPLACE>,
		2358	C<IO::AIO::MAP_SHARED_VALIDATE>,
		2359	C<IO::AIO::MAP_SYNC> or
		2360	C<IO::AIO::MAP_UNINITIALIZED>.
1849		2361
1850	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2362	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1851		2363
1852	C<$offset> is the offset from the start of the file - it generally must be	2364	C<$offset> is the offset from the start of the file - it generally must be
1853	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2365	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1867		2379
1868	=item IO::AIO::munmap $scalar	2380	=item IO::AIO::munmap $scalar
1869		2381
1870	Removes a previous mmap and undefines the C<$scalar>.	2382	Removes a previous mmap and undefines the C<$scalar>.
1871		2383
		2384	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2385
		2386	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2387	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2388	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2389
		2390	Returns true if successful, and false otherwise. If the underlying mmapped
		2391	region has changed address, then the true value has the numerical value
		2392	C<1>, otherwise it has the numerical value C<0>:
		2393
		2394	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2395	or die "mremap: $!";
		2396
		2397	if ($success*1) {
		2398	warn "scalar has chanegd address in memory\n";
		2399	}
		2400
		2401	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2402	implemented, but not supported and might go away in a future version.
		2403
		2404	On systems where this call is not supported or is not emulated, this call
		2405	returns falls and sets C<$!> to C<ENOSYS>.
		2406
		2407	=item IO::AIO::mlockall $flags
		2408
		2409	Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
		2410	but is blocking.
		2411
1872	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef	2412	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1873		2413
1874	Calls the C<munlock> function, undoing the effects of a previous	2414	Calls the C<munlock> function, undoing the effects of a previous
1875	C<aio_mlock> call (see its description for details).	2415	C<aio_mlock> call (see its description for details).
1876		2416
…		…
1878		2418
1879	Calls the C<munlockall> function.	2419	Calls the C<munlockall> function.
1880		2420
1881	On systems that do not implement C<munlockall>, this function returns	2421	On systems that do not implement C<munlockall>, this function returns
1882	ENOSYS, otherwise the return value of C<munlockall>.	2422	ENOSYS, otherwise the return value of C<munlockall>.
		2423
		2424	=item $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		2425
		2426	Uses the GNU/Linux C<accept4(2)> syscall, if available, to accept a socket
		2427	and return the new file handle on success, or sets C<$!> and returns
		2428	C<undef> on error.
		2429
		2430	The remote name of the new socket will be stored in C<$sockaddr>, which
		2431	will be extended to allow for at least C<$sockaddr_maxlen> octets. If the
		2432	socket name does not fit into C<$sockaddr_maxlen> octets, this is signaled
		2433	by returning a longer string in C<$sockaddr>, which might or might not be
		2434	truncated.
		2435
		2436	To accept name-less sockets, use C<undef> for C<$sockaddr> and C<0> for
		2437	C<$sockaddr_maxlen>.
		2438
		2439	The main reasons to use this syscall rather than portable C<accept(2)>
		2440	are that you can specify C<SOCK_NONBLOCK> and/or C<SOCK_CLOEXEC>
		2441	flags and you can accept name-less sockets by specifying C<0> for
		2442	C<$sockaddr_maxlen>, which is sadly not possible with perl's interface to
		2443	C<accept>.
		2444
		2445	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2446
		2447	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2448	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2449	should be the file offset.
		2450
		2451	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2452	silently corrupt the data in this case.
		2453
		2454	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2455	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2456	C<IO::AIO::SPLICE_F_GIFT>.
		2457
		2458	See the C<splice(2)> manpage for details.
		2459
		2460	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2461
		2462	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2463	description for C<IO::AIO::splice> above for details.
		2464
		2465	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2466
		2467	Attempts to query or change the pipe buffer size. Obviously works only
		2468	on pipes, and currently works only on GNU/Linux systems, and fails with
		2469	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2470	size on other systems, drop me a note.
		2471
		2472	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2473
		2474	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2475	C<$flags> is missing or C<0>, then this should be the same as a call to
		2476	perl's built-in C<pipe> function and create a new pipe, and works on
		2477	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2478	(..., 4096, O_BINARY)>.
		2479
		2480	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2481	the given flags (Linux 2.6.27, glibc 2.9).
		2482
		2483	On success, the read and write file handles are returned.
		2484
		2485	On error, nothing will be returned. If the pipe2 syscall is missing and
		2486	C<$flags> is non-zero, fails with C<ENOSYS>.
		2487
		2488	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2489	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2490	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2491
		2492	Example: create a pipe race-free w.r.t. threads and fork:
		2493
		2494	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2495	or die "pipe2: $!\n";
		2496
		2497	=item $fh = IO::AIO::memfd_create $pathname[, $flags]
		2498
		2499	This is a direct interface to the Linux L<memfd_create(2)> system
		2500	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2501	should be C<IO::AIO::MFD_CLOEXEC>.
		2502
		2503	On success, the new memfd filehandle is returned, otherwise returns
		2504	C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
		2505
		2506	Please refer to L<memfd_create(2)> for more info on this call.
		2507
		2508	The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
		2509	C<IO::AIO::MFD_ALLOW_SEALING>, C<IO::AIO::MFD_HUGETLB>,
		2510	C<IO::AIO::MFD_HUGETLB_2MB> and C<IO::AIO::MFD_HUGETLB_1GB>.
		2511
		2512	Example: create a new memfd.
		2513
		2514	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2515	or die "memfd_create: $!\n";
		2516
		2517	=item $fh = IO::AIO::pidfd_open $pid[, $flags]
		2518
		2519	This is an interface to the Linux L<pidfd_open(2)> system call. The
		2520	default for C<$flags> is C<0>.
		2521
		2522	On success, a new pidfd filehandle is returned (that is already set to
		2523	close-on-exec), otherwise returns C<undef>. If the syscall is missing,
		2524	fails with C<ENOSYS>.
		2525
		2526	Example: open pid 6341 as pidfd.
		2527
		2528	my $fh = IO::AIO::pidfd_open 6341
		2529	or die "pidfd_open: $!\n";
		2530
		2531	=item $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
		2532
		2533	This is an interface to the Linux L<pidfd_send_signal> system call. The
		2534	default for C<$siginfo> is C<undef> and the default for C<$flags> is C<0>.
		2535
		2536	Returns the system call status. If the syscall is missing, fails with
		2537	C<ENOSYS>.
		2538
		2539	When specified, C<$siginfo> must be a reference to a hash with one or more
		2540	of the following members:
		2541
		2542	=over
		2543
		2544	=item code - the C<si_code> member
		2545
		2546	=item pid - the C<si_pid> member
		2547
		2548	=item uid - the C<si_uid> member
		2549
		2550	=item value_int - the C<si_value.sival_int> member
		2551
		2552	=item value_ptr - the C<si_value.sival_ptr> member, specified as an integer
		2553
		2554	=back
		2555
		2556	Example: send a SIGKILL to the specified process.
		2557
		2558	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
		2559	and die "pidfd_send_signal: $!\n";
		2560
		2561	Example: send a SIGKILL to the specified process with extra data.
		2562
		2563	my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
		2564	and die "pidfd_send_signal: $!\n";
		2565
		2566	=item $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
		2567
		2568	This is an interface to the Linux L<pidfd_getfd> system call. The default
		2569	for C<$flags> is C<0>.
		2570
		2571	On success, returns a dup'ed copy of the target file descriptor (specified
		2572	as an integer) returned (that is already set to close-on-exec), otherwise
		2573	returns C<undef>. If the syscall is missing, fails with C<ENOSYS>.
		2574
		2575	Example: get a copy of standard error of another process and print soemthing to it.
		2576
		2577	my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
		2578	or die "pidfd_getfd: $!\n";
		2579	print $errfh "stderr\n";
		2580
		2581	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2582
		2583	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2584	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2585
		2586	On success, the new eventfd filehandle is returned, otherwise returns
		2587	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2588
		2589	Please refer to L<eventfd(2)> for more info on this call.
		2590
		2591	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2592	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2593
		2594	Example: create a new eventfd filehandle:
		2595
		2596	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2597	or die "eventfd: $!\n";
		2598
		2599	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2600
		2601	This is a direct interface to the Linux L<timerfd_create(2)> system
		2602	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2603	should be C<IO::AIO::TFD_CLOEXEC>.
		2604
		2605	On success, the new timerfd filehandle is returned, otherwise returns
		2606	C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
		2607
		2608	Please refer to L<timerfd_create(2)> for more info on this call.
		2609
		2610	The following C<$clockid> values are
		2611	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2612	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2613	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2614	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2615
		2616	The following C<$flags> values are available (Linux
		2617	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2618
		2619	Example: create a new timerfd and set it to one-second repeated alarms,
		2620	then wait for two alarms:
		2621
		2622	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2623	or die "timerfd_create: $!\n";
		2624
		2625	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2626	or die "timerfd_settime: $!\n";
		2627
		2628	for (1..2) {
		2629	8 == sysread $fh, my $buf, 8
		2630	or die "timerfd read failure\n";
		2631
		2632	printf "number of expirations (likely 1): %d\n",
		2633	unpack "Q", $buf;
		2634	}
		2635
		2636	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2637
		2638	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2639	call. Please refer to its manpage for more info on this call.
		2640
		2641	The new itimerspec is specified using two (possibly fractional) second
		2642	values, C<$new_interval> and C<$new_value>).
		2643
		2644	On success, the current interval and value are returned (as per
		2645	C<timerfd_gettime>). On failure, the empty list is returned.
		2646
		2647	The following C<$flags> values are
		2648	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2649	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2650
		2651	See C<IO::AIO::timerfd_create> for a full example.
		2652
		2653	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2654
		2655	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2656	call. Please refer to its manpage for more info on this call.
		2657
		2658	On success, returns the current values of interval and value for the given
		2659	timerfd (as potentially fractional second values). On failure, the empty
		2660	list is returned.
1883		2661
1884	=back	2662	=back
1885		2663
1886	=cut	2664	=cut
1887		2665
…		…
1953	the process will result in undefined behaviour. Calling it at any time	2731	the process will result in undefined behaviour. Calling it at any time
1954	will also result in any undefined (by POSIX) behaviour.	2732	will also result in any undefined (by POSIX) behaviour.
1955		2733
1956	=back	2734	=back
1957		2735
		2736	=head2 LINUX-SPECIFIC CALLS
		2737
		2738	When a call is documented as "linux-specific" then this means it
		2739	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2740	availability and compatibility of such calls regardless of the platform
		2741	it is compiled on, so platforms such as FreeBSD which often implement
		2742	these calls will work. When in doubt, call them and see if they fail wth
		2743	C<ENOSYS>.
		2744
1958	=head2 MEMORY USAGE	2745	=head2 MEMORY USAGE
1959		2746
1960	Per-request usage:	2747	Per-request usage:
1961		2748
1962	Each aio request uses - depending on your architecture - around 100-200	2749	Each aio request uses - depending on your architecture - around 100-200
…		…
1974	temporary buffers, and each thread requires a stack and other data	2761	temporary buffers, and each thread requires a stack and other data
1975	structures (usually around 16k-128k, depending on the OS).	2762	structures (usually around 16k-128k, depending on the OS).
1976		2763
1977	=head1 KNOWN BUGS	2764	=head1 KNOWN BUGS
1978		2765
1979	Known bugs will be fixed in the next release.	2766	Known bugs will be fixed in the next release :)
		2767
		2768	=head1 KNOWN ISSUES
		2769
		2770	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2771	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2772	non-created hash slots or other scalars I didn't think of. It's best to
		2773	avoid such and either use scalar variables or making sure that the scalar
		2774	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2775
		2776	I am not sure anything can be done about this, so this is considered a
		2777	known issue, rather than a bug.
1980		2778
1981	=head1 SEE ALSO	2779	=head1 SEE ALSO
1982		2780
1983	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2781	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1984	more natural syntax.	2782	more natural syntax and L<IO::FDPass> for file descriptor passing.
1985		2783
1986	=head1 AUTHOR	2784	=head1 AUTHOR
1987		2785
1988	Marc Lehmann <schmorp@schmorp.de>	2786	Marc Lehmann <schmorp@schmorp.de>
1989	http://home.schmorp.de/	2787	http://home.schmorp.de/

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