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Revision 1.192 by root, Fri May 20 00:00:03 2011 UTC vs.
Revision 1.307 by root, Wed Feb 26 15:32:59 2020 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	IO::AIO - Asynchronous Input/Output	3	IO::AIO - Asynchronous/Advanced Input/Output
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
…		…
58	not well-supported or restricted (GNU/Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
59	files currently, for example), and they would only support aio_read and	59	files currently, for example), and they would only support aio_read and
60	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
61	using threads anyway.	61	using threads anyway.
62		62
		63	In addition to asynchronous I/O, this module also exports some rather
		64	arcane interfaces, such as C<madvise> or linux's C<splice> system call,
		65	which is why the C<A> in C<AIO> can also mean I<advanced>.
		66
63	Although the module will work in the presence of other (Perl-) threads,	67	Although the module will work in the presence of other (Perl-) threads,
64	it is currently not reentrant in any way, so use appropriate locking	68	it is currently not reentrant in any way, so use appropriate locking
65	yourself, always call C<poll_cb> from within the same thread, or never	69	yourself, always call C<poll_cb> from within the same thread, or never
66	call C<poll_cb> (or other C<aio_> functions) recursively.	70	call C<poll_cb> (or other C<aio_> functions) recursively.
67		71
68	=head2 EXAMPLE	72	=head2 EXAMPLE
69		73
70	This is a simple example that uses the EV module and loads	74	This is a simple example that uses the EV module and loads
71	F</etc/passwd> asynchronously:	75	F</etc/passwd> asynchronously:
72		76
73	use Fcntl;
74	use EV;	77	use EV;
75	use IO::AIO;	78	use IO::AIO;
76		79
77	# register the IO::AIO callback with EV	80	# register the IO::AIO callback with EV
78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	81	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
…		…
95		98
96	# file contents now in $contents	99	# file contents now in $contents
97	print $contents;	100	print $contents;
98		101
99	# exit event loop and program	102	# exit event loop and program
100	EV::unloop;	103	EV::break;
101	};	104	};
102	};	105	};
103		106
104	# possibly queue up other requests, or open GUI windows,	107	# possibly queue up other requests, or open GUI windows,
105	# check for sockets etc. etc.	108	# check for sockets etc. etc.
106		109
107	# process events as long as there are some:	110	# process events as long as there are some:
108	EV::loop;	111	EV::run;
109		112
110	=head1 REQUEST ANATOMY AND LIFETIME	113	=head1 REQUEST ANATOMY AND LIFETIME
111		114
112	Every C<aio_*> function creates a request. which is a C data structure not	115	Every C<aio_*> function creates a request. which is a C data structure not
113	directly visible to Perl.	116	directly visible to Perl.
…		…
168	use common::sense;	171	use common::sense;
169		172
170	use base 'Exporter';	173	use base 'Exporter';
171		174
172	BEGIN {	175	BEGIN {
173	our $VERSION = '3.8';	176	our $VERSION = 4.73;
174		177
175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	178	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx	179	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
177	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
178	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead	181	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
		182	aio_pathsync aio_readahead aio_fiemap aio_allocate
179	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
180	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
181	aio_chmod aio_utime aio_truncate	185	aio_chmod aio_utime aio_truncate
182	aio_msync aio_mtouch aio_mlock aio_mlockall	186	aio_msync aio_mtouch aio_mlock aio_mlockall
183	aio_statvfs);	187	aio_statvfs
		188	aio_slurp
		189	aio_wd);
184		190
185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	191	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	192	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
187	min_parallel max_parallel max_idle idle_timeout	193	min_parallel max_parallel max_idle idle_timeout
188	nreqs nready npending nthreads	194	nreqs nready npending nthreads
189	max_poll_time max_poll_reqs	195	max_poll_time max_poll_reqs
190	sendfile fadvise madvise	196	sendfile fadvise madvise
191	mmap munmap munlock munlockall);	197	mmap munmap mremap munlock munlockall);
192		198
193	push @AIO_REQ, qw(aio_busy); # not exported	199	push @AIO_REQ, qw(aio_busy); # not exported
194		200
195	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	201	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
196		202
…		…
200		206
201	=head1 FUNCTIONS	207	=head1 FUNCTIONS
202		208
203	=head2 QUICK OVERVIEW	209	=head2 QUICK OVERVIEW
204		210
205	This section simply lists the prototypes of the most important functions	211	This section simply lists the prototypes most of the functions for
206	for quick reference. See the following sections for function-by-function	212	quick reference. See the following sections for function-by-function
207	documentation.	213	documentation.
208		214
		215	aio_wd $pathname, $callback->($wd)
209	aio_open $pathname, $flags, $mode, $callback->($fh)	216	aio_open $pathname, $flags, $mode, $callback->($fh)
210	aio_close $fh, $callback->($status)	217	aio_close $fh, $callback->($status)
		218	aio_seek $fh,$offset,$whence, $callback->($offs)
211	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	219	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
212	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	220	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
213	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	221	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
214	aio_readahead $fh,$offset,$length, $callback->($retval)	222	aio_readahead $fh,$offset,$length, $callback->($retval)
215	aio_stat $fh_or_path, $callback->($status)	223	aio_stat $fh_or_path, $callback->($status)
216	aio_lstat $fh, $callback->($status)	224	aio_lstat $fh, $callback->($status)
217	aio_statvfs $fh_or_path, $callback->($statvfs)	225	aio_statvfs $fh_or_path, $callback->($statvfs)
218	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	226	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
219	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	227	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		228	aio_chmod $fh_or_path, $mode, $callback->($status)
220	aio_truncate $fh_or_path, $offset, $callback->($status)	229	aio_truncate $fh_or_path, $offset, $callback->($status)
221	aio_chmod $fh_or_path, $mode, $callback->($status)	230	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		231	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
222	aio_unlink $pathname, $callback->($status)	232	aio_unlink $pathname, $callback->($status)
223	aio_mknod $path, $mode, $dev, $callback->($status)	233	aio_mknod $pathname, $mode, $dev, $callback->($status)
224	aio_link $srcpath, $dstpath, $callback->($status)	234	aio_link $srcpath, $dstpath, $callback->($status)
225	aio_symlink $srcpath, $dstpath, $callback->($status)	235	aio_symlink $srcpath, $dstpath, $callback->($status)
226	aio_readlink $path, $callback->($link)	236	aio_readlink $pathname, $callback->($link)
		237	aio_realpath $pathname, $callback->($path)
227	aio_rename $srcpath, $dstpath, $callback->($status)	238	aio_rename $srcpath, $dstpath, $callback->($status)
		239	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
228	aio_mkdir $pathname, $mode, $callback->($status)	240	aio_mkdir $pathname, $mode, $callback->($status)
229	aio_rmdir $pathname, $callback->($status)	241	aio_rmdir $pathname, $callback->($status)
230	aio_readdir $pathname, $callback->($entries)	242	aio_readdir $pathname, $callback->($entries)
231	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	243	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
232	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	244	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
233	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	245	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		246	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
234	aio_load $path, $data, $callback->($status)	247	aio_load $pathname, $data, $callback->($status)
235	aio_copy $srcpath, $dstpath, $callback->($status)	248	aio_copy $srcpath, $dstpath, $callback->($status)
236	aio_move $srcpath, $dstpath, $callback->($status)	249	aio_move $srcpath, $dstpath, $callback->($status)
237	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
238	aio_rmtree $path, $callback->($status)	250	aio_rmtree $pathname, $callback->($status)
		251	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		252	aio_ioctl $fh, $request, $buf, $callback->($status)
239	aio_sync $callback->($status)	253	aio_sync $callback->($status)
		254	aio_syncfs $fh, $callback->($status)
240	aio_fsync $fh, $callback->($status)	255	aio_fsync $fh, $callback->($status)
241	aio_fdatasync $fh, $callback->($status)	256	aio_fdatasync $fh, $callback->($status)
242	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	257	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
243	aio_pathsync $path, $callback->($status)	258	aio_pathsync $pathname, $callback->($status)
244	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	259	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
245	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	260	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
246	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	261	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
247	aio_mlockall $flags, $callback->($status)	262	aio_mlockall $flags, $callback->($status)
248	aio_group $callback->(...)	263	aio_group $callback->(...)
249	aio_nop $callback->()	264	aio_nop $callback->()
…		…
263	IO::AIO::idle_timeout $seconds	278	IO::AIO::idle_timeout $seconds
264	IO::AIO::max_outstanding $maxreqs	279	IO::AIO::max_outstanding $maxreqs
265	IO::AIO::nreqs	280	IO::AIO::nreqs
266	IO::AIO::nready	281	IO::AIO::nready
267	IO::AIO::npending	282	IO::AIO::npending
		283	IO::AIO::reinit
		284
		285	$nfd = IO::AIO::get_fdlimit
		286	IO::AIO::min_fdlimit $nfd
268		287
269	IO::AIO::sendfile $ofh, $ifh, $offset, $count	288	IO::AIO::sendfile $ofh, $ifh, $offset, $count
270	IO::AIO::fadvise $fh, $offset, $len, $advice	289	IO::AIO::fadvise $fh, $offset, $len, $advice
		290
		291	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		292	IO::AIO::munmap $scalar
		293	IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
271	IO::AIO::madvise $scalar, $offset, $length, $advice	294	IO::AIO::madvise $scalar, $offset, $length, $advice
272	IO::AIO::mprotect $scalar, $offset, $length, $protect	295	IO::AIO::mprotect $scalar, $offset, $length, $protect
273	IO::AIO::munlock $scalar, $offset = 0, $length = undef	296	IO::AIO::munlock $scalar, $offset = 0, $length = undef
274	IO::AIO::munlockall	297	IO::AIO::munlockall
275		298
276	=head2 AIO REQUEST FUNCTIONS	299	# stat extensions
		300	$counter = IO::AIO::st_gen
		301	$seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		302	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		303	$nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		304	$seconds = IO::AIO::st_btimesec
		305	($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		306
		307	# very much unportable syscalls
		308	IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
		309	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		310	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		311	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		312	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		313	$fh = IO::AIO::memfd_create $pathname[, $flags]
		314	$fh = IO::AIO::eventfd [$initval, [$flags]]
		315	$fh = IO::AIO::timerfd_create $clockid[, $flags]
		316	($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		317	($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		318
		319	=head2 API NOTES
277		320
278	All the C<aio_*> calls are more or less thin wrappers around the syscall	321	All the C<aio_*> calls are more or less thin wrappers around the syscall
279	with the same name (sans C<aio_>). The arguments are similar or identical,	322	with the same name (sans C<aio_>). The arguments are similar or identical,
280	and they all accept an additional (and optional) C<$callback> argument	323	and they all accept an additional (and optional) C<$callback> argument
281	which must be a code reference. This code reference will get called with	324	which must be a code reference. This code reference will be called after
282	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	325	the syscall has been executed in an asynchronous fashion. The results
283	perl, which usually delivers "false") as its sole argument after the given	326	of the request will be passed as arguments to the callback (and, if an
284	syscall has been executed asynchronously.	327	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		328	most syscalls return C<-1> on error, unlike perl, which usually delivers
		329	"false").
		330
		331	Some requests (such as C<aio_readdir>) pass the actual results and
		332	communicate failures by passing C<undef>.
285		333
286	All functions expecting a filehandle keep a copy of the filehandle	334	All functions expecting a filehandle keep a copy of the filehandle
287	internally until the request has finished.	335	internally until the request has finished.
288		336
289	All functions return request objects of type L<IO::AIO::REQ> that allow	337	All functions return request objects of type L<IO::AIO::REQ> that allow
290	further manipulation of those requests while they are in-flight.	338	further manipulation of those requests while they are in-flight.
291		339
292	The pathnames you pass to these routines I<must> be absolute and	340	The pathnames you pass to these routines I<should> be absolute. The
293	encoded as octets. The reason for the former is that at the time the	341	reason for this is that at the time the request is being executed, the
294	request is being executed, the current working directory could have	342	current working directory could have changed. Alternatively, you can
295	changed. Alternatively, you can make sure that you never change the	343	make sure that you never change the current working directory anywhere
296	current working directory anywhere in the program and then use relative	344	in the program and then use relative paths. You can also take advantage
297	paths.	345	of IO::AIOs working directory abstraction, that lets you specify paths
		346	relative to some previously-opened "working directory object" - see the
		347	description of the C<IO::AIO::WD> class later in this document.
298		348
299	To encode pathnames as octets, either make sure you either: a) always pass	349	To encode pathnames as octets, either make sure you either: a) always pass
300	in filenames you got from outside (command line, readdir etc.) without	350	in filenames you got from outside (command line, readdir etc.) without
301	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	351	tinkering, b) are in your native filesystem encoding, c) use the Encode
302	your pathnames to the locale (or other) encoding in effect in the user	352	module and encode your pathnames to the locale (or other) encoding in
303	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	353	effect in the user environment, d) use Glib::filename_from_unicode on
304	use something else to ensure your scalar has the correct contents.	354	unicode filenames or e) use something else to ensure your scalar has the
		355	correct contents.
305		356
306	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	357	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
307	handles correctly whether it is set or not.	358	handles correctly whether it is set or not.
		359
		360	=head2 AIO REQUEST FUNCTIONS
308		361
309	=over 4	362	=over 4
310		363
311	=item $prev_pri = aioreq_pri [$pri]	364	=item $prev_pri = aioreq_pri [$pri]
312		365
…		…
342		395
343		396
344	=item aio_open $pathname, $flags, $mode, $callback->($fh)	397	=item aio_open $pathname, $flags, $mode, $callback->($fh)
345		398
346	Asynchronously open or create a file and call the callback with a newly	399	Asynchronously open or create a file and call the callback with a newly
347	created filehandle for the file.	400	created filehandle for the file (or C<undef> in case of an error).
348		401
349	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	402	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
350	for an explanation.	403	for an explanation.
351		404
352	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	405	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
368	} else {	421	} else {
369	die "open failed: $!\n";	422	die "open failed: $!\n";
370	}	423	}
371	};	424	};
372		425
		426	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		427	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		428	following POSIX and non-POSIX constants are available (missing ones on
		429	your system are, as usual, C<0>):
		430
		431	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		432	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		433	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, C<O_TTY_INIT> and C<O_ACCMODE>.
		434
373		435
374	=item aio_close $fh, $callback->($status)	436	=item aio_close $fh, $callback->($status)
375		437
376	Asynchronously close a file and call the callback with the result	438	Asynchronously close a file and call the callback with the result
377	code.	439	code.
…		…
386	Or in other words: the file descriptor will be closed, but it will not be	448	Or in other words: the file descriptor will be closed, but it will not be
387	free for reuse until the perl filehandle is closed.	449	free for reuse until the perl filehandle is closed.
388		450
389	=cut	451	=cut
390		452
		453	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		454
		455	Seeks the filehandle to the new C<$offset>, similarly to perl's
		456	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		457	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		458	C<IO::AIO::SEEK_END>).
		459
		460	The resulting absolute offset will be passed to the callback, or C<-1> in
		461	case of an error.
		462
		463	In theory, the C<$whence> constants could be different than the
		464	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		465	so don't panic.
		466
		467	As a GNU/Linux (and maybe Solaris) extension, also the constants
		468	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		469	could be found. No guarantees about suitability for use in C<aio_seek> or
		470	Perl's C<sysseek> can be made though, although I would naively assume they
		471	"just work".
		472
391	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	473	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
392		474
393	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	475	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
394		476
395	Reads or writes C<$length> bytes from or to the specified C<$fh> and	477	Reads or writes C<$length> bytes from or to the specified C<$fh> and
396	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	478	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
397	and calls the callback without the actual number of bytes read (or -1 on	479	calls the callback with the actual number of bytes transferred (or -1 on
398	error, just like the syscall).	480	error, just like the syscall).
399		481
400	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	482	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
401	offset plus the actual number of bytes read.	483	offset plus the actual number of bytes read.
402		484
…		…
427		509
428	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	510	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
429	reading at byte offset C<$in_offset>, and starts writing at the current	511	reading at byte offset C<$in_offset>, and starts writing at the current
430	file offset of C<$out_fh>. Because of that, it is not safe to issue more	512	file offset of C<$out_fh>. Because of that, it is not safe to issue more
431	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	513	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
432	other.	514	other. The same C<$in_fh> works fine though, as this function does not
		515	move or use the file offset of C<$in_fh>.
433		516
434	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than	517	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
435	are written, and there is no way to find out how many bytes have been read	518	are written, and there is no way to find out how many more bytes have been
436	from C<aio_sendfile> alone, as C<aio_sendfile> only provides the number of	519	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
437	bytes written to C<$out_fh>. Only if the result value equals C<$length>	520	number of bytes written to C<$out_fh>. Only if the result value equals
438	one can assume that C<$length> bytes have been read.	521	C<$length> one can assume that C<$length> bytes have been read.
439		522
440	Unlike with other C<aio_> functions, it makes a lot of sense to use	523	Unlike with other C<aio_> functions, it makes a lot of sense to use
441	C<aio_sendfile> on non-blocking sockets, as long as one end (typically	524	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
442	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while	525	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
443	the socket I/O will be non-blocking. Note, however, that you can run into	526	the socket I/O will be non-blocking. Note, however, that you can run
444	a trap where C<aio_sendfile> reads some data with readahead, then fails	527	into a trap where C<aio_sendfile> reads some data with readahead, then
445	to write all data, and when the socket is ready the next time, the data	528	fails to write all data, and when the socket is ready the next time, the
446	in the cache is already lost, forcing C<aio_sendfile> to again hit the	529	data in the cache is already lost, forcing C<aio_sendfile> to again hit
447	disk. Explicit C<aio_read> + C<aio_write> let's you control resource usage	530	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
448	much better.	531	resource usage.
449		532
450	This call tries to make use of a native C<sendfile> syscall to provide	533	This call tries to make use of a native C<sendfile>-like syscall to
451	zero-copy operation. For this to work, C<$out_fh> should refer to a	534	provide zero-copy operation. For this to work, C<$out_fh> should refer to
452	socket, and C<$in_fh> should refer to an mmap'able file.	535	a socket, and C<$in_fh> should refer to an mmap'able file.
453		536
454	If a native sendfile cannot be found or it fails with C<ENOSYS>,	537	If a native sendfile cannot be found or it fails with C<ENOSYS>,
455	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,	538	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
456	it will be emulated, so you can call C<aio_sendfile> on any type of	539	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
457	filehandle regardless of the limitations of the operating system.	540	type of filehandle regardless of the limitations of the operating system.
		541
		542	As native sendfile syscalls (as practically any non-POSIX interface hacked
		543	together in a hurry to improve benchmark numbers) tend to be rather buggy
		544	on many systems, this implementation tries to work around some known bugs
		545	in Linux and FreeBSD kernels (probably others, too), but that might fail,
		546	so you really really should check the return value of C<aio_sendfile> -
		547	fewer bytes than expected might have been transferred.
458		548
459		549
460	=item aio_readahead $fh,$offset,$length, $callback->($retval)	550	=item aio_readahead $fh,$offset,$length, $callback->($retval)
461		551
462	C<aio_readahead> populates the page cache with data from a file so that	552	C<aio_readahead> populates the page cache with data from a file so that
…		…
466	whole pages, so that offset is effectively rounded down to a page boundary	556	whole pages, so that offset is effectively rounded down to a page boundary
467	and bytes are read up to the next page boundary greater than or equal to	557	and bytes are read up to the next page boundary greater than or equal to
468	(off-set+length). C<aio_readahead> does not read beyond the end of the	558	(off-set+length). C<aio_readahead> does not read beyond the end of the
469	file. The current file offset of the file is left unchanged.	559	file. The current file offset of the file is left unchanged.
470		560
471	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	561	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
472	emulated by simply reading the data, which would have a similar effect.	562	be emulated by simply reading the data, which would have a similar effect.
473		563
474		564
475	=item aio_stat $fh_or_path, $callback->($status)	565	=item aio_stat $fh_or_path, $callback->($status)
476		566
477	=item aio_lstat $fh, $callback->($status)	567	=item aio_lstat $fh, $callback->($status)
478		568
479	Works like perl's C<stat> or C<lstat> in void context. The callback will	569	Works almost exactly like perl's C<stat> or C<lstat> in void context. The
480	be called after the stat and the results will be available using C<stat _>	570	callback will be called after the stat and the results will be available
481	or C<-s _> etc...	571	using C<stat _> or C<-s _> and other tests (with the exception of C<-B>
		572	and C<-T>).
482		573
483	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,	574	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
484	for an explanation.	575	for an explanation.
485		576
486	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	577	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
…		…
493	behaviour).	584	behaviour).
494		585
495	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,	586	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
496	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,	587	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
497	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.	588	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		589
		590	To access higher resolution stat timestamps, see L<SUBSECOND STAT TIME
		591	ACCESS>.
498		592
499	Example: Print the length of F</etc/passwd>:	593	Example: Print the length of F</etc/passwd>:
500		594
501	aio_stat "/etc/passwd", sub {	595	aio_stat "/etc/passwd", sub {
502	$_[0] and die "stat failed: $!";	596	$_[0] and die "stat failed: $!";
…		…
546	namemax => 255,	640	namemax => 255,
547	frsize => 1024,	641	frsize => 1024,
548	fsid => 1810	642	fsid => 1810
549	}	643	}
550		644
551
552	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	645	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
553		646
554	Works like perl's C<utime> function (including the special case of $atime	647	Works like perl's C<utime> function (including the special case of $atime
555	and $mtime being undef). Fractional times are supported if the underlying	648	and $mtime being undef). Fractional times are supported if the underlying
556	syscalls support them.	649	syscalls support them.
557		650
558	When called with a pathname, uses utimes(2) if available, otherwise	651	When called with a pathname, uses utimensat(2) or utimes(2) if available,
559	utime(2). If called on a file descriptor, uses futimes(2) if available,	652	otherwise utime(2). If called on a file descriptor, uses futimens(2)
560	otherwise returns ENOSYS, so this is not portable.	653	or futimes(2) if available, otherwise returns ENOSYS, so this is not
		654	portable.
561		655
562	Examples:	656	Examples:
563		657
564	# set atime and mtime to current time (basically touch(1)):	658	# set atime and mtime to current time (basically touch(1)):
565	aio_utime "path", undef, undef;	659	aio_utime "path", undef, undef;
…		…
583	=item aio_truncate $fh_or_path, $offset, $callback->($status)	677	=item aio_truncate $fh_or_path, $offset, $callback->($status)
584		678
585	Works like truncate(2) or ftruncate(2).	679	Works like truncate(2) or ftruncate(2).
586		680
587		681
		682	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		683
		684	Allocates or frees disk space according to the C<$mode> argument. See the
		685	linux C<fallocate> documentation for details.
		686
		687	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		688	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		689	to deallocate a file range.
		690
		691	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		692	(without leaving a hole), C<FALLOC_FL_ZERO_RANGE>, to zero a range,
		693	C<FALLOC_FL_INSERT_RANGE> to insert a range and C<FALLOC_FL_UNSHARE_RANGE>
		694	to unshare shared blocks (see your L<fallocate(2)> manpage).
		695
		696	The file system block size used by C<fallocate> is presumably the
		697	C<f_bsize> returned by C<statvfs>, but different filesystems and filetypes
		698	can dictate other limitations.
		699
		700	If C<fallocate> isn't available or cannot be emulated (currently no
		701	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		702
		703
588	=item aio_chmod $fh_or_path, $mode, $callback->($status)	704	=item aio_chmod $fh_or_path, $mode, $callback->($status)
589		705
590	Works like perl's C<chmod> function.	706	Works like perl's C<chmod> function.
591		707
592		708
…		…
594		710
595	Asynchronously unlink (delete) a file and call the callback with the	711	Asynchronously unlink (delete) a file and call the callback with the
596	result code.	712	result code.
597		713
598		714
599	=item aio_mknod $path, $mode, $dev, $callback->($status)	715	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
600		716
601	[EXPERIMENTAL]	717	[EXPERIMENTAL]
602		718
603	Asynchronously create a device node (or fifo). See mknod(2).	719	Asynchronously create a device node (or fifo). See mknod(2).
604		720
605	The only (POSIX-) portable way of calling this function is:	721	The only (POSIX-) portable way of calling this function is:
606		722
607	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	723	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
608		724
609	See C<aio_stat> for info about some potentially helpful extra constants	725	See C<aio_stat> for info about some potentially helpful extra constants
610	and functions.	726	and functions.
611		727
612	=item aio_link $srcpath, $dstpath, $callback->($status)	728	=item aio_link $srcpath, $dstpath, $callback->($status)
…		…
619		735
620	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	736	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
621	the path C<$dstpath> and call the callback with the result code.	737	the path C<$dstpath> and call the callback with the result code.
622		738
623		739
624	=item aio_readlink $path, $callback->($link)	740	=item aio_readlink $pathname, $callback->($link)
625		741
626	Asynchronously read the symlink specified by C<$path> and pass it to	742	Asynchronously read the symlink specified by C<$path> and pass it to
627	the callback. If an error occurs, nothing or undef gets passed to the	743	the callback. If an error occurs, nothing or undef gets passed to the
628	callback.	744	callback.
629		745
630		746
		747	=item aio_realpath $pathname, $callback->($path)
		748
		749	Asynchronously make the path absolute and resolve any symlinks in
		750	C<$path>. The resulting path only consists of directories (same as
		751	L<Cwd::realpath>).
		752
		753	This request can be used to get the absolute path of the current working
		754	directory by passing it a path of F<.> (a single dot).
		755
		756
631	=item aio_rename $srcpath, $dstpath, $callback->($status)	757	=item aio_rename $srcpath, $dstpath, $callback->($status)
632		758
633	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	759	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
634	rename(2) and call the callback with the result code.	760	rename(2) and call the callback with the result code.
		761
		762	On systems that support the AIO::WD working directory abstraction
		763	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		764	of failing, C<rename> is called on the absolute path of C<$wd>.
		765
		766
		767	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		768
		769	Basically a version of C<aio_rename> with an additional C<$flags>
		770	argument. Calling this with C<$flags=0> is the same as calling
		771	C<aio_rename>.
		772
		773	Non-zero flags are currently only supported on GNU/Linux systems that
		774	support renameat2. Other systems fail with C<ENOSYS> in this case.
		775
		776	The following constants are available (missing ones are, as usual C<0>),
		777	see renameat2(2) for details:
		778
		779	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		780	and C<IO::AIO::RENAME_WHITEOUT>.
635		781
636		782
637	=item aio_mkdir $pathname, $mode, $callback->($status)	783	=item aio_mkdir $pathname, $mode, $callback->($status)
638		784
639	Asynchronously mkdir (create) a directory and call the callback with	785	Asynchronously mkdir (create) a directory and call the callback with
…		…
644	=item aio_rmdir $pathname, $callback->($status)	790	=item aio_rmdir $pathname, $callback->($status)
645		791
646	Asynchronously rmdir (delete) a directory and call the callback with the	792	Asynchronously rmdir (delete) a directory and call the callback with the
647	result code.	793	result code.
648		794
		795	On systems that support the AIO::WD working directory abstraction
		796	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		797	C<rmdir> is called on the absolute path of C<$wd>.
		798
649		799
650	=item aio_readdir $pathname, $callback->($entries)	800	=item aio_readdir $pathname, $callback->($entries)
651		801
652	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	802	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
653	directory (i.e. opendir + readdir + closedir). The entries will not be	803	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
657	array-ref with the filenames.	807	array-ref with the filenames.
658		808
659		809
660	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	810	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
661		811
662	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	812	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
663	behaviour and output format. In case of an error, C<$entries> will be	813	tune behaviour and output format. In case of an error, C<$entries> will be
664	C<undef>.	814	C<undef>.
665		815
666	The flags are a combination of the following constants, ORed together (the	816	The flags are a combination of the following constants, ORed together (the
667	flags will also be passed to the callback, possibly modified):	817	flags will also be passed to the callback, possibly modified):
668		818
669	=over 4	819	=over 4
670		820
671	=item IO::AIO::READDIR_DENTS	821	=item IO::AIO::READDIR_DENTS
672		822
673	When this flag is off, then the callback gets an arrayref consisting of	823	Normally the callback gets an arrayref consisting of names only (as
674	names only (as with C<aio_readdir>), otherwise it gets an arrayref with	824	with C<aio_readdir>). If this flag is set, then the callback gets an
675	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	825	arrayref with C<[$name, $type, $inode]> arrayrefs, each describing a
676	entry in more detail.	826	single directory entry in more detail:
677		827
678	C<$name> is the name of the entry.	828	C<$name> is the name of the entry.
679		829
680	C<$type> is one of the C<IO::AIO::DT_xxx> constants:	830	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
681		831
682	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,	832	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
683	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,	833	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
684	C<IO::AIO::DT_WHT>.	834	C<IO::AIO::DT_WHT>.
685		835
686	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	836	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need
687	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	837	to know, you have to run stat yourself. Also, for speed/memory reasons,
688	scalars are read-only: you can not modify them.	838	the C<$type> scalars are read-only: you must not modify them.
689		839
690	C<$inode> is the inode number (which might not be exact on systems with 64	840	C<$inode> is the inode number (which might not be exact on systems with 64
691	bit inode numbers and 32 bit perls). This field has unspecified content on	841	bit inode numbers and 32 bit perls). This field has unspecified content on
692	systems that do not deliver the inode information.	842	systems that do not deliver the inode information.
693		843
694	=item IO::AIO::READDIR_DIRS_FIRST	844	=item IO::AIO::READDIR_DIRS_FIRST
695		845
696	When this flag is set, then the names will be returned in an order where	846	When this flag is set, then the names will be returned in an order where
697	likely directories come first. This is useful when you need to quickly	847	likely directories come first, in optimal stat order. This is useful when
698	find directories, or you want to find all directories while avoiding to	848	you need to quickly find directories, or you want to find all directories
699	stat() each entry.	849	while avoiding to stat() each entry.
700		850
701	If the system returns type information in readdir, then this is used	851	If the system returns type information in readdir, then this is used
702	to find directories directly. Otherwise, likely directories are files	852	to find directories directly. Otherwise, likely directories are names
703	beginning with ".", or otherwise files with no dots, of which files with	853	beginning with ".", or otherwise names with no dots, of which names with
704	short names are tried first.	854	short names are tried first.
705		855
706	=item IO::AIO::READDIR_STAT_ORDER	856	=item IO::AIO::READDIR_STAT_ORDER
707		857
708	When this flag is set, then the names will be returned in an order	858	When this flag is set, then the names will be returned in an order
709	suitable for stat()'ing each one. That is, when you plan to stat()	859	suitable for stat()'ing each one. That is, when you plan to stat() most or
710	all files in the given directory, then the returned order will likely	860	all files in the given directory, then the returned order will likely be
711	be fastest.	861	faster.
712		862
713	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then	863	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified,
714	the likely dirs come first, resulting in a less optimal stat order.	864	then the likely dirs come first, resulting in a less optimal stat order
		865	for stat'ing all entries, but likely a more optimal order for finding
		866	subdirectories.
715		867
716	=item IO::AIO::READDIR_FOUND_UNKNOWN	868	=item IO::AIO::READDIR_FOUND_UNKNOWN
717		869
718	This flag should not be set when calling C<aio_readdirx>. Instead, it	870	This flag should not be set when calling C<aio_readdirx>. Instead, it
719	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	871	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
720	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	872	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
721	C<$type>'s are known, which can be used to speed up some algorithms.	873	C<$type>'s are known, which can be used to speed up some algorithms.
722		874
723	=back	875	=back
724		876
725		877
		878	=item aio_slurp $pathname, $offset, $length, $data, $callback->($status)
		879
		880	Opens, reads and closes the given file. The data is put into C<$data>,
		881	which is resized as required.
		882
		883	If C<$offset> is negative, then it is counted from the end of the file.
		884
		885	If C<$length> is zero, then the remaining length of the file is
		886	used. Also, in this case, the same limitations to modifying C<$data> apply
		887	as when IO::AIO::mmap is used, i.e. it must only be modified in-place
		888	with C<substr>. If the size of the file is known, specifying a non-zero
		889	C<$length> results in a performance advantage.
		890
		891	This request is similar to the older C<aio_load> request, but since it is
		892	a single request, it might be more efficient to use.
		893
		894	Example: load F</etc/passwd> into C<$passwd>.
		895
		896	my $passwd;
		897	aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
		898	$_[0] >= 0
		899	or die "/etc/passwd: $!\n";
		900
		901	printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
		902	print $passwd;
		903	};
		904	IO::AIO::flush;
		905
		906
726	=item aio_load $path, $data, $callback->($status)	907	=item aio_load $pathname, $data, $callback->($status)
727		908
728	This is a composite request that tries to fully load the given file into	909	This is a composite request that tries to fully load the given file into
729	memory. Status is the same as with aio_read.	910	memory. Status is the same as with aio_read.
		911
		912	Using C<aio_slurp> might be more efficient, as it is a single request.
730		913
731	=cut	914	=cut
732		915
733	sub aio_load($$;$) {	916	sub aio_load($$;$) {
734	my ($path, undef, $cb) = @_;	917	my ($path, undef, $cb) = @_;
…		…
754	=item aio_copy $srcpath, $dstpath, $callback->($status)	937	=item aio_copy $srcpath, $dstpath, $callback->($status)
755		938
756	Try to copy the I<file> (directories not supported as either source or	939	Try to copy the I<file> (directories not supported as either source or
757	destination) from C<$srcpath> to C<$dstpath> and call the callback with	940	destination) from C<$srcpath> to C<$dstpath> and call the callback with
758	a status of C<0> (ok) or C<-1> (error, see C<$!>).	941	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		942
		943	Existing destination files will be truncated.
759		944
760	This is a composite request that creates the destination file with	945	This is a composite request that creates the destination file with
761	mode 0200 and copies the contents of the source file into it using	946	mode 0200 and copies the contents of the source file into it using
762	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	947	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
763	uid/gid, in that order.	948	uid/gid, in that order.
…		…
853	if ($_[0] && $! == EXDEV) {	1038	if ($_[0] && $! == EXDEV) {
854	aioreq_pri $pri;	1039	aioreq_pri $pri;
855	add $grp aio_copy $src, $dst, sub {	1040	add $grp aio_copy $src, $dst, sub {
856	$grp->result ($_[0]);	1041	$grp->result ($_[0]);
857		1042
858	if (!$_[0]) {	1043	unless ($_[0]) {
859	aioreq_pri $pri;	1044	aioreq_pri $pri;
860	add $grp aio_unlink $src;	1045	add $grp aio_unlink $src;
861	}	1046	}
862	};	1047	};
863	} else {	1048	} else {
…		…
866	};	1051	};
867		1052
868	$grp	1053	$grp
869	}	1054	}
870		1055
871	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1056	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
872		1057
873	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1058	Scans a directory (similar to C<aio_readdir>) but additionally tries to
874	efficiently separate the entries of directory C<$path> into two sets of	1059	efficiently separate the entries of directory C<$path> into two sets of
875	names, directories you can recurse into (directories), and ones you cannot	1060	names, directories you can recurse into (directories), and ones you cannot
876	recurse into (everything else, including symlinks to directories).	1061	recurse into (everything else, including symlinks to directories).
877		1062
878	C<aio_scandir> is a composite request that creates of many sub requests_	1063	C<aio_scandir> is a composite request that generates many sub requests.
879	C<$maxreq> specifies the maximum number of outstanding aio requests that	1064	C<$maxreq> specifies the maximum number of outstanding aio requests that
880	this function generates. If it is C<< <= 0 >>, then a suitable default	1065	this function generates. If it is C<< <= 0 >>, then a suitable default
881	will be chosen (currently 4).	1066	will be chosen (currently 4).
882		1067
883	On error, the callback is called without arguments, otherwise it receives	1068	On error, the callback is called without arguments, otherwise it receives
…		…
907	Then entries will be sorted into likely directories a non-initial dot	1092	Then entries will be sorted into likely directories a non-initial dot
908	currently) and likely non-directories (see C<aio_readdirx>). Then every	1093	currently) and likely non-directories (see C<aio_readdirx>). Then every
909	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1094	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
910	in order of their inode numbers. If that succeeds, it assumes that the	1095	in order of their inode numbers. If that succeeds, it assumes that the
911	entry is a directory or a symlink to directory (which will be checked	1096	entry is a directory or a symlink to directory (which will be checked
912	seperately). This is often faster than stat'ing the entry itself because	1097	separately). This is often faster than stat'ing the entry itself because
913	filesystems might detect the type of the entry without reading the inode	1098	filesystems might detect the type of the entry without reading the inode
914	data (e.g. ext2fs filetype feature), even on systems that cannot return	1099	data (e.g. ext2fs filetype feature), even on systems that cannot return
915	the filetype information on readdir.	1100	the filetype information on readdir.
916		1101
917	If the known number of directories (link count - 2) has been reached, the	1102	If the known number of directories (link count - 2) has been reached, the
…		…
933		1118
934	my $grp = aio_group $cb;	1119	my $grp = aio_group $cb;
935		1120
936	$maxreq = 4 if $maxreq <= 0;	1121	$maxreq = 4 if $maxreq <= 0;
937		1122
938	# stat once	1123	# get a wd object
939	aioreq_pri $pri;	1124	aioreq_pri $pri;
940	add $grp aio_stat $path, sub {	1125	add $grp aio_wd $path, sub {
		1126	$_[0]
941	return $grp->result () if $_[0];	1127	or return $grp->result ();
942	my $now = time;
943	my $hash1 = join ":", (stat _)[0,1,3,7,9];
944		1128
945	# read the directory entries	1129	my $wd = [shift, "."];
		1130
		1131	# stat once
946	aioreq_pri $pri;	1132	aioreq_pri $pri;
947	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1133	add $grp aio_stat $wd, sub {
948	my $entries = shift
949	or return $grp->result ();	1134	return $grp->result () if $_[0];
		1135	my $now = time;
		1136	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		1137	my $rdxflags = READDIR_DIRS_FIRST;
950		1138
951	# stat the dir another time	1139	if ((stat _)[3] < 2) {
		1140	# at least one non-POSIX filesystem exists
		1141	# that returns useful DT_type values: btrfs,
		1142	# so optimise for this here by requesting dents
		1143	$rdxflags |= READDIR_DENTS;
		1144	}
		1145
		1146	# read the directory entries
952	aioreq_pri $pri;	1147	aioreq_pri $pri;
953	add $grp aio_stat $path, sub {	1148	add $grp aio_readdirx $wd, $rdxflags, sub {
954	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1149	my ($entries, $flags) = @_
		1150	or return $grp->result ();
955		1151
		1152	if ($rdxflags & READDIR_DENTS) {
		1153	# if we requested type values, see if we can use them directly.
		1154
		1155	# if there were any DT_UNKNOWN entries then we assume we
		1156	# don't know. alternatively, we could assume that if we get
		1157	# one DT_DIR, then all directories are indeed marked with
		1158	# DT_DIR, but this seems not required for btrfs, and this
		1159	# is basically the "btrfs can't get it's act together" code
		1160	# branch.
		1161	unless ($flags & READDIR_FOUND_UNKNOWN) {
		1162	# now we have valid DT_ information for all entries,
		1163	# so use it as an optimisation without further stat's.
		1164	# they must also all be at the beginning of @$entries
		1165	# by now.
		1166
956	my $ndirs;	1167	my $dirs;
957		1168
958	# take the slow route if anything looks fishy
959	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
960	$ndirs = -1;
961	} else {
962	# if nlink == 2, we are finished
963	# for non-posix-fs's, we rely on nlink < 2
964	$ndirs = (stat _)[3] - 2
965	or return $grp->result ([], $entries);
966	}
967
968	my (@dirs, @nondirs);
969
970	my $statgrp = add $grp aio_group sub {
971	$grp->result (\@dirs, \@nondirs);
972	};
973
974	limit $statgrp $maxreq;
975	feed $statgrp sub {
976	return unless @$entries;
977	my $entry = shift @$entries;
978
979	aioreq_pri $pri;
980	add $statgrp aio_stat "$path/$entry/.", sub {
981	if ($_[0] < 0) {	1169	if (@$entries) {
982	push @nondirs, $entry;	1170	for (0 .. $#$entries) {
983	} else {	1171	if ($entries->[$_][1] != DT_DIR) {
984	# need to check for real directory	1172	# splice out directories
985	aioreq_pri $pri;	1173	$dirs = [splice @$entries, 0, $_];
986	add $statgrp aio_lstat "$path/$entry", sub {
987	if (-d _) {
988	push @dirs, $entry;
989
990	unless (--$ndirs) {
991	push @nondirs, @$entries;
992	feed $statgrp;
993	}	1174	last;
994	} else {
995	push @nondirs, $entry;
996	}	1175	}
997	}	1176	}
		1177
		1178	# if we didn't find any non-dir, then all entries are dirs
		1179	unless ($dirs) {
		1180	($dirs, $entries) = ($entries, []);
		1181	}
		1182	} else {
		1183	# directory is empty, so there are no sbdirs
		1184	$dirs = [];
998	}	1185	}
		1186
		1187	# either splice'd the directories out or the dir was empty.
		1188	# convert dents to filenames
		1189	$_ = $_->[0] for @$dirs;
		1190	$_ = $_->[0] for @$entries;
		1191
		1192	return $grp->result ($dirs, $entries);
		1193	}
		1194
		1195	# cannot use, so return to our old ways
		1196	# by pretending we only scanned for names.
		1197	$_ = $_->[0] for @$entries;
		1198	}
		1199
		1200	# stat the dir another time
		1201	aioreq_pri $pri;
		1202	add $grp aio_stat $wd, sub {
		1203	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		1204
		1205	my $ndirs;
		1206
		1207	# take the slow route if anything looks fishy
		1208	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
		1209	$ndirs = -1;
		1210	} else {
		1211	# if nlink == 2, we are finished
		1212	# for non-posix-fs's, we rely on nlink < 2
		1213	$ndirs = (stat _)[3] - 2
		1214	or return $grp->result ([], $entries);
		1215	}
		1216
		1217	my (@dirs, @nondirs);
		1218
		1219	my $statgrp = add $grp aio_group sub {
		1220	$grp->result (\@dirs, \@nondirs);
		1221	};
		1222
		1223	limit $statgrp $maxreq;
		1224	feed $statgrp sub {
		1225	return unless @$entries;
		1226	my $entry = shift @$entries;
		1227
		1228	aioreq_pri $pri;
		1229	$wd->[1] = "$entry/.";
		1230	add $statgrp aio_stat $wd, sub {
		1231	if ($_[0] < 0) {
		1232	push @nondirs, $entry;
		1233	} else {
		1234	# need to check for real directory
		1235	aioreq_pri $pri;
		1236	$wd->[1] = $entry;
		1237	add $statgrp aio_lstat $wd, sub {
		1238	if (-d _) {
		1239	push @dirs, $entry;
		1240
		1241	unless (--$ndirs) {
		1242	push @nondirs, @$entries;
		1243	feed $statgrp;
		1244	}
		1245	} else {
		1246	push @nondirs, $entry;
		1247	}
		1248	}
		1249	}
		1250	};
999	};	1251	};
1000	};	1252	};
1001	};	1253	};
1002	};	1254	};
1003	};	1255	};
1004		1256
1005	$grp	1257	$grp
1006	}	1258	}
1007		1259
1008	=item aio_rmtree $path, $callback->($status)	1260	=item aio_rmtree $pathname, $callback->($status)
1009		1261
1010	Delete a directory tree starting (and including) C<$path>, return the	1262	Delete a directory tree starting (and including) C<$path>, return the
1011	status of the final C<rmdir> only. This is a composite request that	1263	status of the final C<rmdir> only. This is a composite request that
1012	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1264	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
1013	everything else.	1265	everything else.
1014		1266
1015	=cut	1267	=cut
1016		1268
…		…
1038	};	1290	};
1039		1291
1040	$grp	1292	$grp
1041	}	1293	}
1042		1294
		1295	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1296
		1297	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1298
		1299	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1300	they execute asynchronously and pass the return value to the callback.
		1301
		1302	Both calls can be used for a lot of things, some of which make more sense
		1303	to run asynchronously in their own thread, while some others make less
		1304	sense. For example, calls that block waiting for external events, such
		1305	as locking, will also lock down an I/O thread while it is waiting, which
		1306	can deadlock the whole I/O system. At the same time, there might be no
		1307	alternative to using a thread to wait.
		1308
		1309	So in general, you should only use these calls for things that do
		1310	(filesystem) I/O, not for things that wait for other events (network,
		1311	other processes), although if you are careful and know what you are doing,
		1312	you still can.
		1313
		1314	The following constants are available and can be used for normal C<ioctl>
		1315	and C<fcntl> as well (missing ones are, as usual C<0>):
		1316
		1317	C<F_DUPFD_CLOEXEC>,
		1318
		1319	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1320
		1321	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1322
		1323	C<F_ADD_SEALS>, C<F_GET_SEALS>, C<F_SEAL_SEAL>, C<F_SEAL_SHRINK>, C<F_SEAL_GROW> and
		1324	C<F_SEAL_WRITE>.
		1325
		1326	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1327	C<FS_IOC_FIEMAP>.
		1328
		1329	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1330	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1331
		1332	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1333	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1334	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1335	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1336	C<FS_FL_USER_MODIFIABLE>.
		1337
		1338	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1339	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1340	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1341	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1342
1043	=item aio_sync $callback->($status)	1343	=item aio_sync $callback->($status)
1044		1344
1045	Asynchronously call sync and call the callback when finished.	1345	Asynchronously call sync and call the callback when finished.
1046		1346
1047	=item aio_fsync $fh, $callback->($status)	1347	=item aio_fsync $fh, $callback->($status)
…		…
1054	Asynchronously call fdatasync on the given filehandle and call the	1354	Asynchronously call fdatasync on the given filehandle and call the
1055	callback with the fdatasync result code.	1355	callback with the fdatasync result code.
1056		1356
1057	If this call isn't available because your OS lacks it or it couldn't be	1357	If this call isn't available because your OS lacks it or it couldn't be
1058	detected, it will be emulated by calling C<fsync> instead.	1358	detected, it will be emulated by calling C<fsync> instead.
		1359
		1360	=item aio_syncfs $fh, $callback->($status)
		1361
		1362	Asynchronously call the syncfs syscall to sync the filesystem associated
		1363	to the given filehandle and call the callback with the syncfs result
		1364	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1365	errno to C<ENOSYS> nevertheless.
1059		1366
1060	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1367	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
1061		1368
1062	Sync the data portion of the file specified by C<$offset> and C<$length>	1369	Sync the data portion of the file specified by C<$offset> and C<$length>
1063	to disk (but NOT the metadata), by calling the Linux-specific	1370	to disk (but NOT the metadata), by calling the Linux-specific
…		…
1067	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1374	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
1068	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1375	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
1069	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1376	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
1070	manpage for details.	1377	manpage for details.
1071		1378
1072	=item aio_pathsync $path, $callback->($status)	1379	=item aio_pathsync $pathname, $callback->($status)
1073		1380
1074	This request tries to open, fsync and close the given path. This is a	1381	This request tries to open, fsync and close the given path. This is a
1075	composite request intended to sync directories after directory operations	1382	composite request intended to sync directories after directory operations
1076	(E.g. rename). This might not work on all operating systems or have any	1383	(E.g. rename). This might not work on all operating systems or have any
1077	specific effect, but usually it makes sure that directory changes get	1384	specific effect, but usually it makes sure that directory changes get
…		…
1108	};	1415	};
1109		1416
1110	$grp	1417	$grp
1111	}	1418	}
1112		1419
1113	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1420	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
1114		1421
1115	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1422	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
1116	scalars (see the C<IO::AIO::mmap> function, although it also works on data	1423	scalars (see the C<IO::AIO::mmap> function, although it also works on data
1117	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the	1424	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1118	scalar must only be modified in-place while an aio operation is pending on	1425	scalar must only be modified in-place while an aio operation is pending on
…		…
1120		1427
1121	It calls the C<msync> function of your OS, if available, with the memory	1428	It calls the C<msync> function of your OS, if available, with the memory
1122	area starting at C<$offset> in the string and ending C<$length> bytes	1429	area starting at C<$offset> in the string and ending C<$length> bytes
1123	later. If C<$length> is negative, counts from the end, and if C<$length>	1430	later. If C<$length> is negative, counts from the end, and if C<$length>
1124	is C<undef>, then it goes till the end of the string. The flags can be	1431	is C<undef>, then it goes till the end of the string. The flags can be
1125	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1432	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1126	C<IO::AIO::MS_SYNC>.	1433	C<IO::AIO::MS_INVALIDATE>.
1127		1434
1128	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1435	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1129		1436
1130	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1437	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1131	scalars.	1438	scalars.
1132		1439
1133	It touches (reads or writes) all memory pages in the specified	1440	It touches (reads or writes) all memory pages in the specified
1134	range inside the scalar. All caveats and parameters are the same	1441	range inside the scalar. All caveats and parameters are the same
1135	as for C<aio_msync>, above, except for flags, which must be either	1442	as for C<aio_msync>, above, except for flags, which must be either
1136	C<0> (which reads all pages and ensures they are instantiated) or	1443	C<0> (which reads all pages and ensures they are instantiated) or
1137	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1444	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1138	writing an octet from it, which dirties the page).	1445	writing an octet from it, which dirties the page).
1139		1446
1140	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)	1447	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1141		1448
1142	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1449	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
…		…
1161	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;	1468	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1162	aio_mlock $data; # mlock in background	1469	aio_mlock $data; # mlock in background
1163		1470
1164	=item aio_mlockall $flags, $callback->($status)	1471	=item aio_mlockall $flags, $callback->($status)
1165		1472
1166	Calls the C<mlockall> function with the given C<$flags> (a combination of	1473	Calls the C<mlockall> function with the given C<$flags> (a
1167	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).	1474	combination of C<IO::AIO::MCL_CURRENT>, C<IO::AIO::MCL_FUTURE> and
		1475	C<IO::AIO::MCL_ONFAULT>).
1168		1476
1169	On systems that do not implement C<mlockall>, this function returns C<-1>	1477	On systems that do not implement C<mlockall>, this function returns C<-1>
1170	and sets errno to C<ENOSYS>.	1478	and sets errno to C<ENOSYS>. Similarly, flag combinations not supported
		1479	by the system result in a return value of C<-1> with errno being set to
		1480	C<EINVAL>.
1171		1481
1172	Note that the corresponding C<munlockall> is synchronous and is	1482	Note that the corresponding C<munlockall> is synchronous and is
1173	documented under L<MISCELLANEOUS FUNCTIONS>.	1483	documented under L<MISCELLANEOUS FUNCTIONS>.
1174		1484
1175	Example: asynchronously lock all current and future pages into memory.	1485	Example: asynchronously lock all current and future pages into memory.
1176		1486
1177	aio_mlockall IO::AIO::MCL_FUTURE;	1487	aio_mlockall IO::AIO::MCL_FUTURE;
		1488
		1489	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1490
		1491	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1492	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1493	the ioctl is not available on your OS, then this request will fail with
		1494	C<ENOSYS>.
		1495
		1496	C<$start> is the starting offset to query extents for, C<$length> is the
		1497	size of the range to query - if it is C<undef>, then the whole file will
		1498	be queried.
		1499
		1500	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1501	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1502	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1503	the data portion.
		1504
		1505	C<$count> is the maximum number of extent records to return. If it is
		1506	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1507	case, if it is C<0>, then the callback receives the number of extents
		1508	instead of the extents themselves (which is unreliable, see below).
		1509
		1510	If an error occurs, the callback receives no arguments. The special
		1511	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1512
		1513	Otherwise, the callback receives an array reference with extent
		1514	structures. Each extent structure is an array reference itself, with the
		1515	following members:
		1516
		1517	[$logical, $physical, $length, $flags]
		1518
		1519	Flags is any combination of the following flag values (typically either C<0>
		1520	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1521
		1522	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1523	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1524	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1525	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1526	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1527	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1528
		1529	At the time of this writing (Linux 3.2), this request is unreliable unless
		1530	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1531	it to return all extents of a range for files with a large number of
		1532	extents. The code (only) works around all these issues if C<$count> is
		1533	C<undef>.
1178		1534
1179	=item aio_group $callback->(...)	1535	=item aio_group $callback->(...)
1180		1536
1181	This is a very special aio request: Instead of doing something, it is a	1537	This is a very special aio request: Instead of doing something, it is a
1182	container for other aio requests, which is useful if you want to bundle	1538	container for other aio requests, which is useful if you want to bundle
…		…
1219	like sleep and file handle readable/writable, the overhead this creates is	1575	like sleep and file handle readable/writable, the overhead this creates is
1220	immense (it blocks a thread for a long time) so do not use this function	1576	immense (it blocks a thread for a long time) so do not use this function
1221	except to put your application under artificial I/O pressure.	1577	except to put your application under artificial I/O pressure.
1222		1578
1223	=back	1579	=back
		1580
		1581
		1582	=head2 IO::AIO::WD - multiple working directories
		1583
		1584	Your process only has one current working directory, which is used by all
		1585	threads. This makes it hard to use relative paths (some other component
		1586	could call C<chdir> at any time, and it is hard to control when the path
		1587	will be used by IO::AIO).
		1588
		1589	One solution for this is to always use absolute paths. This usually works,
		1590	but can be quite slow (the kernel has to walk the whole path on every
		1591	access), and can also be a hassle to implement.
		1592
		1593	Newer POSIX systems have a number of functions (openat, fdopendir,
		1594	futimensat and so on) that make it possible to specify working directories
		1595	per operation.
		1596
		1597	For portability, and because the clowns who "designed", or shall I write,
		1598	perpetrated this new interface were obviously half-drunk, this abstraction
		1599	cannot be perfect, though.
		1600
		1601	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1602	object. This object stores the canonicalised, absolute version of the
		1603	path, and on systems that allow it, also a directory file descriptor.
		1604
		1605	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1606	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1607	object and a pathname instead (or the IO::AIO::WD object alone, which
		1608	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1609	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1610	to that IO::AIO::WD object.
		1611
		1612	For example, to get a wd object for F</etc> and then stat F<passwd>
		1613	inside, you would write:
		1614
		1615	aio_wd "/etc", sub {
		1616	my $etcdir = shift;
		1617
		1618	# although $etcdir can be undef on error, there is generally no reason
		1619	# to check for errors here, as aio_stat will fail with ENOENT
		1620	# when $etcdir is undef.
		1621
		1622	aio_stat [$etcdir, "passwd"], sub {
		1623	# yay
		1624	};
		1625	};
		1626
		1627	The fact that C<aio_wd> is a request and not a normal function shows that
		1628	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1629	which is why it is done asynchronously.
		1630
		1631	To stat the directory obtained with C<aio_wd> above, one could write
		1632	either of the following three request calls:
		1633
		1634	aio_lstat "/etc" , sub { ... # pathname as normal string
		1635	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1636	aio_lstat $wd , sub { ... # shorthand for the previous
		1637
		1638	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1639	object and the pathname string, so you could write the following without
		1640	causing any issues due to C<$path> getting reused:
		1641
		1642	my $path = [$wd, undef];
		1643
		1644	for my $name (qw(abc def ghi)) {
		1645	$path->[1] = $name;
		1646	aio_stat $path, sub {
		1647	# ...
		1648	};
		1649	}
		1650
		1651	There are some caveats: when directories get renamed (or deleted), the
		1652	pathname string doesn't change, so will point to the new directory (or
		1653	nowhere at all), while the directory fd, if available on the system,
		1654	will still point to the original directory. Most functions accepting a
		1655	pathname will use the directory fd on newer systems, and the string on
		1656	older systems. Some functions (such as C<aio_realpath>) will always rely on
		1657	the string form of the pathname.
		1658
		1659	So this functionality is mainly useful to get some protection against
		1660	C<chdir>, to easily get an absolute path out of a relative path for future
		1661	reference, and to speed up doing many operations in the same directory
		1662	(e.g. when stat'ing all files in a directory).
		1663
		1664	The following functions implement this working directory abstraction:
		1665
		1666	=over 4
		1667
		1668	=item aio_wd $pathname, $callback->($wd)
		1669
		1670	Asynchonously canonicalise the given pathname and convert it to an
		1671	IO::AIO::WD object representing it. If possible and supported on the
		1672	system, also open a directory fd to speed up pathname resolution relative
		1673	to this working directory.
		1674
		1675	If something goes wrong, then C<undef> is passwd to the callback instead
		1676	of a working directory object and C<$!> is set appropriately. Since
		1677	passing C<undef> as working directory component of a pathname fails the
		1678	request with C<ENOENT>, there is often no need for error checking in the
		1679	C<aio_wd> callback, as future requests using the value will fail in the
		1680	expected way.
		1681
		1682	=item IO::AIO::CWD
		1683
		1684	This is a compile time constant (object) that represents the process
		1685	current working directory.
		1686
		1687	Specifying this object as working directory object for a pathname is as if
		1688	the pathname would be specified directly, without a directory object. For
		1689	example, these calls are functionally identical:
		1690
		1691	aio_stat "somefile", sub { ... };
		1692	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1693
		1694	=back
		1695
		1696	To recover the path associated with an IO::AIO::WD object, you can use
		1697	C<aio_realpath>:
		1698
		1699	aio_realpath $wd, sub {
		1700	warn "path is $_[0]\n";
		1701	};
		1702
		1703	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1704	sometimes, fall back to using an absolue path.
1224		1705
1225	=head2 IO::AIO::REQ CLASS	1706	=head2 IO::AIO::REQ CLASS
1226		1707
1227	All non-aggregate C<aio_*> functions return an object of this class when	1708	All non-aggregate C<aio_*> functions return an object of this class when
1228	called in non-void context.	1709	called in non-void context.
…		…
1346		1827
1347	Sets a feeder/generator on this group: every group can have an attached	1828	Sets a feeder/generator on this group: every group can have an attached
1348	generator that generates requests if idle. The idea behind this is that,	1829	generator that generates requests if idle. The idea behind this is that,
1349	although you could just queue as many requests as you want in a group,	1830	although you could just queue as many requests as you want in a group,
1350	this might starve other requests for a potentially long time. For example,	1831	this might starve other requests for a potentially long time. For example,
1351	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1832	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1352	delaying any later requests for a long time.	1833	requests, delaying any later requests for a long time.
1353		1834
1354	To avoid this, and allow incremental generation of requests, you can	1835	To avoid this, and allow incremental generation of requests, you can
1355	instead a group and set a feeder on it that generates those requests. The	1836	instead a group and set a feeder on it that generates those requests. The
1356	feed callback will be called whenever there are few enough (see C<limit>,	1837	feed callback will be called whenever there are few enough (see C<limit>,
1357	below) requests active in the group itself and is expected to queue more	1838	below) requests active in the group itself and is expected to queue more
…		…
1389	The default value for the limit is C<0>, but note that setting a feeder	1870	The default value for the limit is C<0>, but note that setting a feeder
1390	automatically bumps it up to C<2>.	1871	automatically bumps it up to C<2>.
1391		1872
1392	=back	1873	=back
1393		1874
		1875
1394	=head2 SUPPORT FUNCTIONS	1876	=head2 SUPPORT FUNCTIONS
1395		1877
1396	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1878	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
1397		1879
1398	=over 4	1880	=over 4
…		…
1406		1888
1407	See C<poll_cb> for an example.	1889	See C<poll_cb> for an example.
1408		1890
1409	=item IO::AIO::poll_cb	1891	=item IO::AIO::poll_cb
1410		1892
1411	Process some outstanding events on the result pipe. You have to call	1893	Process some requests that have reached the result phase (i.e. they have
		1894	been executed but the results are not yet reported). You have to call
		1895	this "regularly" to finish outstanding requests.
		1896
1412	this regularly. Returns C<0> if all events could be processed (or there	1897	Returns C<0> if all events could be processed (or there were no
1413	were no events to process), or C<-1> if it returned earlier for whatever	1898	events to process), or C<-1> if it returned earlier for whatever
1414	reason. Returns immediately when no events are outstanding. The amount of	1899	reason. Returns immediately when no events are outstanding. The amount
1415	events processed depends on the settings of C<IO::AIO::max_poll_req> and	1900	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
1416	C<IO::AIO::max_poll_time>.	1901	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
1417		1902
1418	If not all requests were processed for whatever reason, the filehandle	1903	If not all requests were processed for whatever reason, the poll file
1419	will still be ready when C<poll_cb> returns, so normally you don't have to	1904	descriptor will still be ready when C<poll_cb> returns, so normally you
1420	do anything special to have it called later.	1905	don't have to do anything special to have it called later.
1421		1906
1422	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes	1907	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
1423	ready, it can be beneficial to call this function from loops which submit	1908	ready, it can be beneficial to call this function from loops which submit
1424	a lot of requests, to make sure the results get processed when they become	1909	a lot of requests, to make sure the results get processed when they become
1425	available and not just when the loop is finished and the event loop takes	1910	available and not just when the loop is finished and the event loop takes
…		…
1434	poll => 'r', async => 1,	1919	poll => 'r', async => 1,
1435	cb => \&IO::AIO::poll_cb);	1920	cb => \&IO::AIO::poll_cb);
1436		1921
1437	=item IO::AIO::poll_wait	1922	=item IO::AIO::poll_wait
1438		1923
1439	If there are any outstanding requests and none of them in the result	1924	Wait until either at least one request is in the result phase or no
1440	phase, wait till the result filehandle becomes ready for reading (simply	1925	requests are outstanding anymore.
1441	does a C<select> on the filehandle. This is useful if you want to	1926
1442	synchronously wait for some requests to finish).	1927	This is useful if you want to synchronously wait for some requests to
		1928	become ready, without actually handling them.
1443		1929
1444	See C<nreqs> for an example.	1930	See C<nreqs> for an example.
1445		1931
1446	=item IO::AIO::poll	1932	=item IO::AIO::poll
1447		1933
…		…
1458		1944
1459	Strictly equivalent to:	1945	Strictly equivalent to:
1460		1946
1461	IO::AIO::poll_wait, IO::AIO::poll_cb	1947	IO::AIO::poll_wait, IO::AIO::poll_cb
1462	while IO::AIO::nreqs;	1948	while IO::AIO::nreqs;
		1949
		1950	This function can be useful at program aborts, to make sure outstanding
		1951	I/O has been done (C<IO::AIO> uses an C<END> block which already calls
		1952	this function on normal exits), or when you are merely using C<IO::AIO>
		1953	for its more advanced functions, rather than for async I/O, e.g.:
		1954
		1955	my ($dirs, $nondirs);
		1956	IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
		1957	IO::AIO::flush;
		1958	# $dirs, $nondirs are now set
1463		1959
1464	=item IO::AIO::max_poll_reqs $nreqs	1960	=item IO::AIO::max_poll_reqs $nreqs
1465		1961
1466	=item IO::AIO::max_poll_time $seconds	1962	=item IO::AIO::max_poll_time $seconds
1467		1963
…		…
1494	poll => 'r', nice => 1,	1990	poll => 'r', nice => 1,
1495	cb => &IO::AIO::poll_cb);	1991	cb => &IO::AIO::poll_cb);
1496		1992
1497	=back	1993	=back
1498		1994
		1995
1499	=head3 CONTROLLING THE NUMBER OF THREADS	1996	=head3 CONTROLLING THE NUMBER OF THREADS
1500		1997
1501	=over	1998	=over
1502		1999
1503	=item IO::AIO::min_parallel $nthreads	2000	=item IO::AIO::min_parallel $nthreads
…		…
1555	Sets the minimum idle timeout (default 10) after which worker threads are	2052	Sets the minimum idle timeout (default 10) after which worker threads are
1556	allowed to exit. SEe C<IO::AIO::max_idle>.	2053	allowed to exit. SEe C<IO::AIO::max_idle>.
1557		2054
1558	=item IO::AIO::max_outstanding $maxreqs	2055	=item IO::AIO::max_outstanding $maxreqs
1559		2056
		2057	Sets the maximum number of outstanding requests to C<$nreqs>. If
		2058	you do queue up more than this number of requests, the next call to
		2059	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		2060	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		2061	longer exceeded.
		2062
		2063	In other words, this setting does not enforce a queue limit, but can be
		2064	used to make poll functions block if the limit is exceeded.
		2065
1560	This is a very bad function to use in interactive programs because it	2066	This is a very bad function to use in interactive programs because it
1561	blocks, and a bad way to reduce concurrency because it is inexact: Better	2067	blocks, and a bad way to reduce concurrency because it is inexact: Better
1562	use an C<aio_group> together with a feed callback.	2068	use an C<aio_group> together with a feed callback.
1563		2069
1564	Sets the maximum number of outstanding requests to C<$nreqs>. If you	2070	Its main use is in scripts without an event loop - when you want to stat
1565	do queue up more than this number of requests, the next call to the	2071	a lot of files, you can write something like this:
1566	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1567	function will block until the limit is no longer exceeded.
1568		2072
1569	The default value is very large, so there is no practical limit on the	2073	IO::AIO::max_outstanding 32;
1570	number of outstanding requests.
1571		2074
1572	You can still queue as many requests as you want. Therefore,	2075	for my $path (...) {
1573	C<max_outstanding> is mainly useful in simple scripts (with low values) or	2076	aio_stat $path , ...;
1574	as a stop gap to shield against fatal memory overflow (with large values).	2077	IO::AIO::poll_cb;
		2078	}
		2079
		2080	IO::AIO::flush;
		2081
		2082	The call to C<poll_cb> inside the loop will normally return instantly, but
		2083	as soon as more thna C<32> reqeusts are in-flight, it will block until
		2084	some requests have been handled. This keeps the loop from pushing a large
		2085	number of C<aio_stat> requests onto the queue.
		2086
		2087	The default value for C<max_outstanding> is very large, so there is no
		2088	practical limit on the number of outstanding requests.
1575		2089
1576	=back	2090	=back
		2091
1577		2092
1578	=head3 STATISTICAL INFORMATION	2093	=head3 STATISTICAL INFORMATION
1579		2094
1580	=over	2095	=over
1581		2096
…		…
1599	Returns the number of requests currently in the pending state (executed,	2114	Returns the number of requests currently in the pending state (executed,
1600	but not yet processed by poll_cb).	2115	but not yet processed by poll_cb).
1601		2116
1602	=back	2117	=back
1603		2118
		2119
		2120	=head3 SUBSECOND STAT TIME ACCESS
		2121
		2122	Both C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> functions can
		2123	generally find access/modification and change times with subsecond time
		2124	accuracy of the system supports it, but perl's built-in functions only
		2125	return the integer part.
		2126
		2127	The following functions return the timestamps of the most recent
		2128	stat with subsecond precision on most systems and work both after
		2129	C<aio_stat>/C<aio_lstat> and perl's C<stat>/C<lstat> calls. Their return
		2130	value is only meaningful after a successful C<stat>/C<lstat> call, or
		2131	during/after a successful C<aio_stat>/C<aio_lstat> callback.
		2132
		2133	This is similar to the L<Time::HiRes> C<stat> functions, but can return
		2134	full resolution without rounding and work with standard perl C<stat>,
		2135	alleviating the need to call the special C<Time::HiRes> functions, which
		2136	do not act like their perl counterparts.
		2137
		2138	On operating systems or file systems where subsecond time resolution is
		2139	not supported or could not be detected, a fractional part of C<0> is
		2140	returned, so it is always safe to call these functions.
		2141
		2142	=over 4
		2143
		2144	=item $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
		2145
		2146	Return the access, modication, change or birth time, respectively,
		2147	including fractional part. Due to the limited precision of floating point,
		2148	the accuracy on most platforms is only a bit better than milliseconds
		2149	for times around now - see the I<nsec> function family, below, for full
		2150	accuracy.
		2151
		2152	File birth time is only available when the OS and perl support it (on
		2153	FreeBSD and NetBSD at the time of this writing, although support is
		2154	adaptive, so if your OS/perl gains support, IO::AIO can take advantage of
		2155	it). On systems where it isn't available, C<0> is currently returned, but
		2156	this might change to C<undef> in a future version.
		2157
		2158	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
		2159
		2160	Returns access, modification, change and birth time all in one go, and
		2161	maybe more times in the future version.
		2162
		2163	=item $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
		2164
		2165	Return the fractional access, modifcation, change or birth time, in nanoseconds,
		2166	as an integer in the range C<0> to C<999999999>.
		2167
		2168	Note that no accessors are provided for access, modification and
		2169	change times - you need to get those from C<stat _> if required (C<int
		2170	IO::AIO::st_atime> and so on will I<not> generally give you the correct
		2171	value).
		2172
		2173	=item $seconds = IO::AIO::st_btimesec
		2174
		2175	The (integral) seconds part of the file birth time, if available.
		2176
		2177	=item ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
		2178
		2179	Like the functions above, but returns all four times in one go (and maybe
		2180	more in future versions).
		2181
		2182	=item $counter = IO::AIO::st_gen
		2183
		2184	Returns the generation counter (in practice this is just a random number)
		2185	of the file. This is only available on platforms which have this member in
		2186	their C<struct stat> (most BSDs at the time of this writing) and generally
		2187	only to the root usert. If unsupported, C<0> is returned, but this might
		2188	change to C<undef> in a future version.
		2189
		2190	=back
		2191
		2192	Example: print the high resolution modification time of F</etc>, using
		2193	C<stat>, and C<IO::AIO::aio_stat>.
		2194
		2195	if (stat "/etc") {
		2196	printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
		2197	}
		2198
		2199	IO::AIO::aio_stat "/etc", sub {
		2200	$_[0]
		2201	and return;
		2202
		2203	printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
		2204	};
		2205
		2206	IO::AIO::flush;
		2207
		2208	Output of the awbove on my system, showing reduced and full accuracy:
		2209
		2210	stat(/etc) mtime: 1534043702.020808
		2211	aio_stat(/etc) mtime: 1534043702.020807792
		2212
		2213
1604	=head3 MISCELLANEOUS FUNCTIONS	2214	=head3 MISCELLANEOUS FUNCTIONS
1605		2215
1606	IO::AIO implements some functions that might be useful, but are not	2216	IO::AIO implements some functions that are useful when you want to use
1607	asynchronous.	2217	some "Advanced I/O" function not available to in Perl, without going the
		2218	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2219	counterpart.
1608		2220
1609	=over 4	2221	=over 4
		2222
		2223	=item $numfd = IO::AIO::get_fdlimit
		2224
		2225	Tries to find the current file descriptor limit and returns it, or
		2226	C<undef> and sets C<$!> in case of an error. The limit is one larger than
		2227	the highest valid file descriptor number.
		2228
		2229	=item IO::AIO::min_fdlimit [$numfd]
		2230
		2231	Try to increase the current file descriptor limit(s) to at least C<$numfd>
		2232	by changing the soft or hard file descriptor resource limit. If C<$numfd>
		2233	is missing, it will try to set a very high limit, although this is not
		2234	recommended when you know the actual minimum that you require.
		2235
		2236	If the limit cannot be raised enough, the function makes a best-effort
		2237	attempt to increase the limit as much as possible, using various
		2238	tricks, while still failing. You can query the resulting limit using
		2239	C<IO::AIO::get_fdlimit>.
		2240
		2241	If an error occurs, returns C<undef> and sets C<$!>, otherwise returns
		2242	true.
1610		2243
1611	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2244	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1612		2245
1613	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,	2246	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
1614	but is blocking (this makes most sense if you know the input data is	2247	but is blocking (this makes most sense if you know the input data is
…		…
1619		2252
1620	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2253	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1621		2254
1622	Simply calls the C<posix_fadvise> function (see its	2255	Simply calls the C<posix_fadvise> function (see its
1623	manpage for details). The following advice constants are	2256	manpage for details). The following advice constants are
1624	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2257	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1625	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2258	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1626	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2259	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1627		2260
1628	On systems that do not implement C<posix_fadvise>, this function returns	2261	On systems that do not implement C<posix_fadvise>, this function returns
1629	ENOSYS, otherwise the return value of C<posix_fadvise>.	2262	ENOSYS, otherwise the return value of C<posix_fadvise>.
1630		2263
1631	=item IO::AIO::madvise $scalar, $offset, $len, $advice	2264	=item IO::AIO::madvise $scalar, $offset, $len, $advice
1632		2265
1633	Simply calls the C<posix_madvise> function (see its	2266	Simply calls the C<posix_madvise> function (see its
1634	manpage for details). The following advice constants are	2267	manpage for details). The following advice constants are
1635	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,	2268	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
1636	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.	2269	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>,
		2270	C<IO::AIO::MADV_DONTNEED>.
		2271
		2272	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2273	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2274	will be reduced to fit into the C<$scalar>.
1637		2275
1638	On systems that do not implement C<posix_madvise>, this function returns	2276	On systems that do not implement C<posix_madvise>, this function returns
1639	ENOSYS, otherwise the return value of C<posix_madvise>.	2277	ENOSYS, otherwise the return value of C<posix_madvise>.
1640		2278
1641	=item IO::AIO::mprotect $scalar, $offset, $len, $protect	2279	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
1642		2280
1643	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed	2281	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
1644	$scalar (see its manpage for details). The following protect	2282	$scalar (see its manpage for details). The following protect
1645	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,	2283	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
1646	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.	2284	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2285
		2286	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2287	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2288	will be reduced to fit into the C<$scalar>.
1647		2289
1648	On systems that do not implement C<mprotect>, this function returns	2290	On systems that do not implement C<mprotect>, this function returns
1649	ENOSYS, otherwise the return value of C<mprotect>.	2291	ENOSYS, otherwise the return value of C<mprotect>.
1650		2292
1651	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	2293	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1652		2294
1653	Memory-maps a file (or anonymous memory range) and attaches it to the	2295	Memory-maps a file (or anonymous memory range) and attaches it to the
1654	given C<$scalar>, which will act like a string scalar.	2296	given C<$scalar>, which will act like a string scalar. Returns true on
		2297	success, and false otherwise.
1655		2298
		2299	The scalar must exist, but its contents do not matter - this means you
		2300	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2301	the scalar first.
		2302
1656	The only operations allowed on the scalar are C<substr>/C<vec> that don't	2303	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
1657	change the string length, and most read-only operations such as copying it	2304	which don't change the string length, and most read-only operations such
1658	or searching it with regexes and so on.	2305	as copying it or searching it with regexes and so on.
1659		2306
1660	Anything else is unsafe and will, at best, result in memory leaks.	2307	Anything else is unsafe and will, at best, result in memory leaks.
1661		2308
1662	The memory map associated with the C<$scalar> is automatically removed	2309	The memory map associated with the C<$scalar> is automatically removed
1663	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or	2310	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
1664	C<IO::AIO::munmap> functions are called.	2311	or C<IO::AIO::munmap> functions are called on it.
1665		2312
1666	This calls the C<mmap>(2) function internally. See your system's manual	2313	This calls the C<mmap>(2) function internally. See your system's manual
1667	page for details on the C<$length>, C<$prot> and C<$flags> parameters.	2314	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
1668		2315
1669	The C<$length> must be larger than zero and smaller than the actual	2316	The C<$length> must be larger than zero and smaller than the actual
1670	filesize.	2317	filesize.
1671		2318
1672	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,	2319	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
1673	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,	2320	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
1674		2321
1675	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or	2322	C<$flags> can be a combination of
1676	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when	2323	C<IO::AIO::MAP_SHARED> or
1677	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>	2324	C<IO::AIO::MAP_PRIVATE>,
		2325	or a number of system-specific flags (when not available, the are C<0>):
1678	(which is set to C<MAP_ANON> if your system only provides this	2326	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
1679	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,	2327	C<IO::AIO::MAP_LOCKED>,
1680	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or	2328	C<IO::AIO::MAP_NORESERVE>,
		2329	C<IO::AIO::MAP_POPULATE>,
1681	C<IO::AIO::MAP_NONBLOCK>	2330	C<IO::AIO::MAP_NONBLOCK>,
		2331	C<IO::AIO::MAP_FIXED>,
		2332	C<IO::AIO::MAP_GROWSDOWN>,
		2333	C<IO::AIO::MAP_32BIT>,
		2334	C<IO::AIO::MAP_HUGETLB> or
		2335	C<IO::AIO::MAP_STACK>.
1682		2336
1683	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.	2337	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
1684		2338
1685	C<$offset> is the offset from the start of the file - it generally must be	2339	C<$offset> is the offset from the start of the file - it generally must be
1686	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.	2340	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
…		…
1700		2354
1701	=item IO::AIO::munmap $scalar	2355	=item IO::AIO::munmap $scalar
1702		2356
1703	Removes a previous mmap and undefines the C<$scalar>.	2357	Removes a previous mmap and undefines the C<$scalar>.
1704		2358
		2359	=item IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, $new_address = 0]
		2360
		2361	Calls the Linux-specific mremap(2) system call. The C<$scalar> must have
		2362	been mapped by C<IO::AIO::mmap>, and C<$flags> must currently either be
		2363	C<0> or C<IO::AIO::MREMAP_MAYMOVE>.
		2364
		2365	Returns true if successful, and false otherwise. If the underlying mmapped
		2366	region has changed address, then the true value has the numerical value
		2367	C<1>, otherwise it has the numerical value C<0>:
		2368
		2369	my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
		2370	or die "mremap: $!";
		2371
		2372	if ($success*1) {
		2373	warn "scalar has chanegd address in memory\n";
		2374	}
		2375
		2376	C<IO::AIO::MREMAP_FIXED> and the C<$new_address> argument are currently
		2377	implemented, but not supported and might go away in a future version.
		2378
		2379	On systems where this call is not supported or is not emulated, this call
		2380	returns falls and sets C<$!> to C<ENOSYS>.
		2381
		2382	=item IO::AIO::mlockall $flags
		2383
		2384	Calls the C<eio_mlockall_sync> function, which is like C<aio_mlockall>,
		2385	but is blocking.
		2386
1705	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef	2387	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
1706		2388
1707	Calls the C<munlock> function, undoing the effects of a previous	2389	Calls the C<munlock> function, undoing the effects of a previous
1708	C<aio_mlock> call (see its description for details).	2390	C<aio_mlock> call (see its description for details).
1709		2391
…		…
1711		2393
1712	Calls the C<munlockall> function.	2394	Calls the C<munlockall> function.
1713		2395
1714	On systems that do not implement C<munlockall>, this function returns	2396	On systems that do not implement C<munlockall>, this function returns
1715	ENOSYS, otherwise the return value of C<munlockall>.	2397	ENOSYS, otherwise the return value of C<munlockall>.
		2398
		2399	=item $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
		2400
		2401	Uses the GNU/Linux C<accept4(2)> syscall, if available, to accept a socket
		2402	and return the new file handle on success, or sets C<$!> and returns
		2403	C<undef> on error.
		2404
		2405	The remote name of the new socket will be stored in C<$sockaddr>, which
		2406	will be extended to allow for at least C<$sockaddr_maxlen> octets. If the
		2407	socket name does not fit into C<$sockaddr_maxlen> octets, this is signaled
		2408	by returning a longer string in C<$sockaddr>, which might or might not be
		2409	truncated.
		2410
		2411	To accept name-less sockets, use C<undef> for C<$sockaddr> and C<0> for
		2412	C<$sockaddr_maxlen>.
		2413
		2414	The main reasons to use this syscall rather than portable C«accept(2)>
		2415	are that you can specify C<SOCK_NONBLOCK> and/or C<SOCK_CLOEXEC>
		2416	flags and you can accept name-less sockets by specifying C<0> for
		2417	C<$sockaddr_maxlen>, which is sadly not possible with perl's interface to
		2418	C<accept>.
		2419
		2420	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2421
		2422	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2423	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2424	should be the file offset.
		2425
		2426	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2427	silently corrupt the data in this case.
		2428
		2429	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2430	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2431	C<IO::AIO::SPLICE_F_GIFT>.
		2432
		2433	See the C<splice(2)> manpage for details.
		2434
		2435	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2436
		2437	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2438	description for C<IO::AIO::splice> above for details.
		2439
		2440	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2441
		2442	Attempts to query or change the pipe buffer size. Obviously works only
		2443	on pipes, and currently works only on GNU/Linux systems, and fails with
		2444	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2445	size on other systems, drop me a note.
		2446
		2447	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2448
		2449	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2450	C<$flags> is missing or C<0>, then this should be the same as a call to
		2451	perl's built-in C<pipe> function and create a new pipe, and works on
		2452	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2453	(..., 4096, O_BINARY)>.
		2454
		2455	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2456	the given flags (Linux 2.6.27, glibc 2.9).
		2457
		2458	On success, the read and write file handles are returned.
		2459
		2460	On error, nothing will be returned. If the pipe2 syscall is missing and
		2461	C<$flags> is non-zero, fails with C<ENOSYS>.
		2462
		2463	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2464	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2465	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2466
		2467	Example: create a pipe race-free w.r.t. threads and fork:
		2468
		2469	my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
		2470	or die "pipe2: $!\n";
		2471
		2472	=item $fh = IO::AIO::memfd_create $pathname[, $flags]
		2473
		2474	This is a direct interface to the Linux L<memfd_create(2)> system
		2475	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2476	should be C<IO::AIO::MFD_CLOEXEC>.
		2477
		2478	On success, the new memfd filehandle is returned, otherwise returns
		2479	C<undef>. If the memfd_create syscall is missing, fails with C<ENOSYS>.
		2480
		2481	Please refer to L<memfd_create(2)> for more info on this call.
		2482
		2483	The following C<$flags> values are available: C<IO::AIO::MFD_CLOEXEC>,
		2484	C<IO::AIO::MFD_ALLOW_SEALING> and C<IO::AIO::MFD_HUGETLB>.
		2485
		2486	Example: create a new memfd.
		2487
		2488	my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
		2489	or die "m,emfd_create: $!\n";
		2490	=item $fh = IO::AIO::eventfd [$initval, [$flags]]
		2491
		2492	This is a direct interface to the Linux L<eventfd(2)> system call. The
		2493	(unhelpful) defaults for C<$initval> and C<$flags> are C<0> for both.
		2494
		2495	On success, the new eventfd filehandle is returned, otherwise returns
		2496	C<undef>. If the eventfd syscall is missing, fails with C<ENOSYS>.
		2497
		2498	Please refer to L<eventfd(2)> for more info on this call.
		2499
		2500	The following symbol flag values are available: C<IO::AIO::EFD_CLOEXEC>,
		2501	C<IO::AIO::EFD_NONBLOCK> and C<IO::AIO::EFD_SEMAPHORE> (Linux 2.6.30).
		2502
		2503	Example: create a new eventfd filehandle:
		2504
		2505	$fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
		2506	or die "eventfd: $!\n";
		2507
		2508	=item $fh = IO::AIO::timerfd_create $clockid[, $flags]
		2509
		2510	This is a direct interface to the Linux L<timerfd_create(2)> system
		2511	call. The (unhelpful) default for C<$flags> is C<0>, but your default
		2512	should be C<IO::AIO::TFD_CLOEXEC>.
		2513
		2514	On success, the new timerfd filehandle is returned, otherwise returns
		2515	C<undef>. If the timerfd_create syscall is missing, fails with C<ENOSYS>.
		2516
		2517	Please refer to L<timerfd_create(2)> for more info on this call.
		2518
		2519	The following C<$clockid> values are
		2520	available: C<IO::AIO::CLOCK_REALTIME>, C<IO::AIO::CLOCK_MONOTONIC>
		2521	C<IO::AIO::CLOCK_CLOCK_BOOTTIME> (Linux 3.15)
		2522	C<IO::AIO::CLOCK_CLOCK_REALTIME_ALARM> (Linux 3.11) and
		2523	C<IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM> (Linux 3.11).
		2524
		2525	The following C<$flags> values are available (Linux
		2526	2.6.27): C<IO::AIO::TFD_NONBLOCK> and C<IO::AIO::TFD_CLOEXEC>.
		2527
		2528	Example: create a new timerfd and set it to one-second repeated alarms,
		2529	then wait for two alarms:
		2530
		2531	my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
		2532	or die "timerfd_create: $!\n";
		2533
		2534	defined IO::AIO::timerfd_settime $fh, 0, 1, 1
		2535	or die "timerfd_settime: $!\n";
		2536
		2537	for (1..2) {
		2538	8 == sysread $fh, my $buf, 8
		2539	or die "timerfd read failure\n";
		2540
		2541	printf "number of expirations (likely 1): %d\n",
		2542	unpack "Q", $buf;
		2543	}
		2544
		2545	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
		2546
		2547	This is a direct interface to the Linux L<timerfd_settime(2)> system
		2548	call. Please refer to its manpage for more info on this call.
		2549
		2550	The new itimerspec is specified using two (possibly fractional) second
		2551	values, C<$new_interval> and C<$new_value>).
		2552
		2553	On success, the current interval and value are returned (as per
		2554	C<timerfd_gettime>). On failure, the empty list is returned.
		2555
		2556	The following C<$flags> values are
		2557	available: C<IO::AIO::TFD_TIMER_ABSTIME> and
		2558	C<IO::AIO::TFD_TIMER_CANCEL_ON_SET>.
		2559
		2560	See C<IO::AIO::timerfd_create> for a full example.
		2561
		2562	=item ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
		2563
		2564	This is a direct interface to the Linux L<timerfd_gettime(2)> system
		2565	call. Please refer to its manpage for more info on this call.
		2566
		2567	On success, returns the current values of interval and value for the given
		2568	timerfd (as potentially fractional second values). On failure, the empty
		2569	list is returned.
1716		2570
1717	=back	2571	=back
1718		2572
1719	=cut	2573	=cut
1720		2574
…		…
1755	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	2609	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1756	\&IO::AIO::poll_cb);	2610	\&IO::AIO::poll_cb);
1757		2611
1758	=head2 FORK BEHAVIOUR	2612	=head2 FORK BEHAVIOUR
1759		2613
1760	This module should do "the right thing" when the process using it forks:	2614	Usage of pthreads in a program changes the semantics of fork
		2615	considerably. Specifically, only async-safe functions can be called after
		2616	fork. Perl doesn't know about this, so in general, you cannot call fork
		2617	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2618	pthreads, so this applies, but many other extensions and (for inexplicable
		2619	reasons) perl itself often is linked against pthreads, so this limitation
		2620	applies to quite a lot of perls.
1761		2621
1762	Before the fork, IO::AIO enters a quiescent state where no requests	2622	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1763	can be added in other threads and no results will be processed. After	2623	only works in the process that loaded it. Forking is fully supported, but
1764	the fork the parent simply leaves the quiescent state and continues	2624	using IO::AIO in the child is not.
1765	request/result processing, while the child frees the request/result queue
1766	(so that the requests started before the fork will only be handled in the
1767	parent). Threads will be started on demand until the limit set in the
1768	parent process has been reached again.
1769		2625
1770	In short: the parent will, after a short pause, continue as if fork had	2626	You might get around by not I<using> IO::AIO before (or after)
1771	not been called, while the child will act as if IO::AIO has not been used	2627	forking. You could also try to call the L<IO::AIO::reinit> function in the
1772	yet.	2628	child:
		2629
		2630	=over 4
		2631
		2632	=item IO::AIO::reinit
		2633
		2634	Abandons all current requests and I/O threads and simply reinitialises all
		2635	data structures. This is not an operation supported by any standards, but
		2636	happens to work on GNU/Linux and some newer BSD systems.
		2637
		2638	The only reasonable use for this function is to call it after forking, if
		2639	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2640	the process will result in undefined behaviour. Calling it at any time
		2641	will also result in any undefined (by POSIX) behaviour.
		2642
		2643	=back
		2644
		2645	=head2 LINUX-SPECIFIC CALLS
		2646
		2647	When a call is documented as "linux-specific" then this means it
		2648	originated on GNU/Linux. C<IO::AIO> will usually try to autodetect the
		2649	availability and compatibility of such calls regardless of the platform
		2650	it is compiled on, so platforms such as FreeBSD which often implement
		2651	these calls will work. When in doubt, call them and see if they fail wth
		2652	C<ENOSYS>.
1773		2653
1774	=head2 MEMORY USAGE	2654	=head2 MEMORY USAGE
1775		2655
1776	Per-request usage:	2656	Per-request usage:
1777		2657
…		…
1790	temporary buffers, and each thread requires a stack and other data	2670	temporary buffers, and each thread requires a stack and other data
1791	structures (usually around 16k-128k, depending on the OS).	2671	structures (usually around 16k-128k, depending on the OS).
1792		2672
1793	=head1 KNOWN BUGS	2673	=head1 KNOWN BUGS
1794		2674
1795	Known bugs will be fixed in the next release.	2675	Known bugs will be fixed in the next release :)
		2676
		2677	=head1 KNOWN ISSUES
		2678
		2679	Calls that try to "import" foreign memory areas (such as C<IO::AIO::mmap>
		2680	or C<IO::AIO::aio_slurp>) do not work with generic lvalues, such as
		2681	non-created hash slots or other scalars I didn't think of. It's best to
		2682	avoid such and either use scalar variables or making sure that the scalar
		2683	exists (e.g. by storing C<undef>) and isn't "funny" (e.g. tied).
		2684
		2685	I am not sure anything can be done about this, so this is considered a
		2686	known issue, rather than a bug.
1796		2687
1797	=head1 SEE ALSO	2688	=head1 SEE ALSO
1798		2689
1799	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a	2690	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
1800	more natural syntax.	2691	more natural syntax and L<IO::FDPass> for file descriptor passing.
1801		2692
1802	=head1 AUTHOR	2693	=head1 AUTHOR
1803		2694
1804	Marc Lehmann <schmorp@schmorp.de>	2695	Marc Lehmann <schmorp@schmorp.de>
1805	http://home.schmorp.de/	2696	http://home.schmorp.de/

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