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Revision 1.171 by root, Sat Jan 2 14:24:32 2010 UTC vs.
Revision 1.270 by root, Fri Jun 23 03:23:19 2017 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
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
10	my $fh = shift	10	my $fh = shift
11	or die "/etc/passwd: $!";	11	or die "/etc/passwd: $!";
12	...	12	...
13	};	13	};
14		14
…		…
25	my $req = aio_unlink "/tmp/file", sub { };	25	my $req = aio_unlink "/tmp/file", sub { };
26	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
27		27
28	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
29	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
30
31	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
32	use AnyEvent::AIO;
33
34	# EV integration
35	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
36
37	# Event integration
38	Event->io (fd => IO::AIO::poll_fileno,
39	poll => 'r',
40	cb => \&IO::AIO::poll_cb);
41
42	# Glib/Gtk2 integration
43	add_watch Glib::IO IO::AIO::poll_fileno,
44	in => sub { IO::AIO::poll_cb; 1 };
45
46	# Tk integration
47	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
48	readable => \&IO::AIO::poll_cb);
49
50	# Danga::Socket integration
51	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
52	\&IO::AIO::poll_cb);
53		30
54	=head1 DESCRIPTION	31	=head1 DESCRIPTION
55		32
56	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
57	operating system supports. It is implemented as an interface to C<libeio>	34	operating system supports. It is implemented as an interface to C<libeio>
…		…
81	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
82	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
83	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
84	using threads anyway.	61	using threads anyway.
85		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
86	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,
87	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
88	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
89	call C<poll_cb> (or other C<aio_> functions) recursively.	70	call C<poll_cb> (or other C<aio_> functions) recursively.
90		71
91	=head2 EXAMPLE	72	=head2 EXAMPLE
92		73
93	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
94	F</etc/passwd> asynchronously:	75	F</etc/passwd> asynchronously:
95		76
96	use Fcntl;
97	use EV;	77	use EV;
98	use IO::AIO;	78	use IO::AIO;
99		79
100	# register the IO::AIO callback with EV	80	# register the IO::AIO callback with EV
101	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;
102		82
103	# queue the request to open /etc/passwd	83	# queue the request to open /etc/passwd
104	aio_open "/etc/passwd", O_RDONLY, 0, sub {	84	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
105	my $fh = shift	85	my $fh = shift
106	or die "error while opening: $!";	86	or die "error while opening: $!";
107		87
108	# stat'ing filehandles is generally non-blocking	88	# stat'ing filehandles is generally non-blocking
109	my $size = -s $fh;	89	my $size = -s $fh;
…		…
118		98
119	# file contents now in $contents	99	# file contents now in $contents
120	print $contents;	100	print $contents;
121		101
122	# exit event loop and program	102	# exit event loop and program
123	EV::unloop;	103	EV::break;
124	};	104	};
125	};	105	};
126		106
127	# possibly queue up other requests, or open GUI windows,	107	# possibly queue up other requests, or open GUI windows,
128	# check for sockets etc. etc.	108	# check for sockets etc. etc.
129		109
130	# process events as long as there are some:	110	# process events as long as there are some:
131	EV::loop;	111	EV::run;
132		112
133	=head1 REQUEST ANATOMY AND LIFETIME	113	=head1 REQUEST ANATOMY AND LIFETIME
134		114
135	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
136	directly visible to Perl.	116	directly visible to Perl.
…		…
191	use common::sense;	171	use common::sense;
192		172
193	use base 'Exporter';	173	use base 'Exporter';
194		174
195	BEGIN {	175	BEGIN {
196	our $VERSION = '3.4';	176	our $VERSION = 4.35;
197		177
198	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
199	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
200	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
201	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
202	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
203	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
204	aio_chmod aio_utime aio_truncate	185	aio_chmod aio_utime aio_truncate
205	aio_msync aio_mtouch);	186	aio_msync aio_mtouch aio_mlock aio_mlockall
		187	aio_statvfs
		188	aio_wd);
206		189
207	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	190	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
208	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	191	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
209	min_parallel max_parallel max_idle	192	min_parallel max_parallel max_idle idle_timeout
210	nreqs nready npending nthreads	193	nreqs nready npending nthreads
211	max_poll_time max_poll_reqs	194	max_poll_time max_poll_reqs
212	sendfile fadvise);	195	sendfile fadvise madvise
		196	mmap munmap munlock munlockall);
213		197
214	push @AIO_REQ, qw(aio_busy); # not exported	198	push @AIO_REQ, qw(aio_busy); # not exported
215		199
216	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	200	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
217		201
…		…
219	XSLoader::load ("IO::AIO", $VERSION);	203	XSLoader::load ("IO::AIO", $VERSION);
220	}	204	}
221		205
222	=head1 FUNCTIONS	206	=head1 FUNCTIONS
223		207
224	=head2 AIO REQUEST FUNCTIONS	208	=head2 QUICK OVERVIEW
		209
		210	This section simply lists the prototypes most of the functions for
		211	quick reference. See the following sections for function-by-function
		212	documentation.
		213
		214	aio_wd $pathname, $callback->($wd)
		215	aio_open $pathname, $flags, $mode, $callback->($fh)
		216	aio_close $fh, $callback->($status)
		217	aio_seek $fh,$offset,$whence, $callback->($offs)
		218	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		219	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		220	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		221	aio_readahead $fh,$offset,$length, $callback->($retval)
		222	aio_stat $fh_or_path, $callback->($status)
		223	aio_lstat $fh, $callback->($status)
		224	aio_statvfs $fh_or_path, $callback->($statvfs)
		225	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		226	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		227	aio_chmod $fh_or_path, $mode, $callback->($status)
		228	aio_truncate $fh_or_path, $offset, $callback->($status)
		229	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		230	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		231	aio_unlink $pathname, $callback->($status)
		232	aio_mknod $pathname, $mode, $dev, $callback->($status)
		233	aio_link $srcpath, $dstpath, $callback->($status)
		234	aio_symlink $srcpath, $dstpath, $callback->($status)
		235	aio_readlink $pathname, $callback->($link)
		236	aio_realpath $pathname, $callback->($path)
		237	aio_rename $srcpath, $dstpath, $callback->($status)
		238	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		239	aio_mkdir $pathname, $mode, $callback->($status)
		240	aio_rmdir $pathname, $callback->($status)
		241	aio_readdir $pathname, $callback->($entries)
		242	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		243	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		244	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		245	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		246	aio_load $pathname, $data, $callback->($status)
		247	aio_copy $srcpath, $dstpath, $callback->($status)
		248	aio_move $srcpath, $dstpath, $callback->($status)
		249	aio_rmtree $pathname, $callback->($status)
		250	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		251	aio_ioctl $fh, $request, $buf, $callback->($status)
		252	aio_sync $callback->($status)
		253	aio_syncfs $fh, $callback->($status)
		254	aio_fsync $fh, $callback->($status)
		255	aio_fdatasync $fh, $callback->($status)
		256	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		257	aio_pathsync $pathname, $callback->($status)
		258	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
		259	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		260	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		261	aio_mlockall $flags, $callback->($status)
		262	aio_group $callback->(...)
		263	aio_nop $callback->()
		264
		265	$prev_pri = aioreq_pri [$pri]
		266	aioreq_nice $pri_adjust
		267
		268	IO::AIO::poll_wait
		269	IO::AIO::poll_cb
		270	IO::AIO::poll
		271	IO::AIO::flush
		272	IO::AIO::max_poll_reqs $nreqs
		273	IO::AIO::max_poll_time $seconds
		274	IO::AIO::min_parallel $nthreads
		275	IO::AIO::max_parallel $nthreads
		276	IO::AIO::max_idle $nthreads
		277	IO::AIO::idle_timeout $seconds
		278	IO::AIO::max_outstanding $maxreqs
		279	IO::AIO::nreqs
		280	IO::AIO::nready
		281	IO::AIO::npending
		282
		283	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		284	IO::AIO::fadvise $fh, $offset, $len, $advice
		285	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		286	IO::AIO::munmap $scalar
		287	IO::AIO::madvise $scalar, $offset, $length, $advice
		288	IO::AIO::mprotect $scalar, $offset, $length, $protect
		289	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		290	IO::AIO::munlockall
		291
		292	=head2 API NOTES
225		293
226	All the C<aio_*> calls are more or less thin wrappers around the syscall	294	All the C<aio_*> calls are more or less thin wrappers around the syscall
227	with the same name (sans C<aio_>). The arguments are similar or identical,	295	with the same name (sans C<aio_>). The arguments are similar or identical,
228	and they all accept an additional (and optional) C<$callback> argument	296	and they all accept an additional (and optional) C<$callback> argument
229	which must be a code reference. This code reference will get called with	297	which must be a code reference. This code reference will be called after
230	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	298	the syscall has been executed in an asynchronous fashion. The results
231	perl, which usually delivers "false") as its sole argument after the given	299	of the request will be passed as arguments to the callback (and, if an
232	syscall has been executed asynchronously.	300	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		301	most syscalls return C<-1> on error, unlike perl, which usually delivers
		302	"false").
		303
		304	Some requests (such as C<aio_readdir>) pass the actual results and
		305	communicate failures by passing C<undef>.
233		306
234	All functions expecting a filehandle keep a copy of the filehandle	307	All functions expecting a filehandle keep a copy of the filehandle
235	internally until the request has finished.	308	internally until the request has finished.
236		309
237	All functions return request objects of type L<IO::AIO::REQ> that allow	310	All functions return request objects of type L<IO::AIO::REQ> that allow
238	further manipulation of those requests while they are in-flight.	311	further manipulation of those requests while they are in-flight.
239		312
240	The pathnames you pass to these routines I<must> be absolute and	313	The pathnames you pass to these routines I<should> be absolute. The
241	encoded as octets. The reason for the former is that at the time the	314	reason for this is that at the time the request is being executed, the
242	request is being executed, the current working directory could have	315	current working directory could have changed. Alternatively, you can
243	changed. Alternatively, you can make sure that you never change the	316	make sure that you never change the current working directory anywhere
244	current working directory anywhere in the program and then use relative	317	in the program and then use relative paths. You can also take advantage
245	paths.	318	of IO::AIOs working directory abstraction, that lets you specify paths
		319	relative to some previously-opened "working directory object" - see the
		320	description of the C<IO::AIO::WD> class later in this document.
246		321
247	To encode pathnames as octets, either make sure you either: a) always pass	322	To encode pathnames as octets, either make sure you either: a) always pass
248	in filenames you got from outside (command line, readdir etc.) without	323	in filenames you got from outside (command line, readdir etc.) without
249	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	324	tinkering, b) are in your native filesystem encoding, c) use the Encode
250	your pathnames to the locale (or other) encoding in effect in the user	325	module and encode your pathnames to the locale (or other) encoding in
251	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	326	effect in the user environment, d) use Glib::filename_from_unicode on
252	use something else to ensure your scalar has the correct contents.	327	unicode filenames or e) use something else to ensure your scalar has the
		328	correct contents.
253		329
254	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	330	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
255	handles correctly whether it is set or not.	331	handles correctly whether it is set or not.
		332
		333	=head2 AIO REQUEST FUNCTIONS
256		334
257	=over 4	335	=over 4
258		336
259	=item $prev_pri = aioreq_pri [$pri]	337	=item $prev_pri = aioreq_pri [$pri]
260		338
…		…
290		368
291		369
292	=item aio_open $pathname, $flags, $mode, $callback->($fh)	370	=item aio_open $pathname, $flags, $mode, $callback->($fh)
293		371
294	Asynchronously open or create a file and call the callback with a newly	372	Asynchronously open or create a file and call the callback with a newly
295	created filehandle for the file.	373	created filehandle for the file (or C<undef> in case of an error).
296		374
297	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	375	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
298	for an explanation.	376	for an explanation.
299		377
300	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	378	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
307	by the umask in effect then the request is being executed, so better never	385	by the umask in effect then the request is being executed, so better never
308	change the umask.	386	change the umask.
309		387
310	Example:	388	Example:
311		389
312	aio_open "/etc/passwd", O_RDONLY, 0, sub {	390	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
313	if ($_[0]) {	391	if ($_[0]) {
314	print "open successful, fh is $_[0]\n";	392	print "open successful, fh is $_[0]\n";
315	...	393	...
316	} else {	394	} else {
317	die "open failed: $!\n";	395	die "open failed: $!\n";
318	}	396	}
319	};	397	};
320		398
		399	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		400	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		401	following POSIX and non-POSIX constants are available (missing ones on
		402	your system are, as usual, C<0>):
		403
		404	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		405	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		406	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
		407
321		408
322	=item aio_close $fh, $callback->($status)	409	=item aio_close $fh, $callback->($status)
323		410
324	Asynchronously close a file and call the callback with the result	411	Asynchronously close a file and call the callback with the result
325	code.	412	code.
…		…
334	Or in other words: the file descriptor will be closed, but it will not be	421	Or in other words: the file descriptor will be closed, but it will not be
335	free for reuse until the perl filehandle is closed.	422	free for reuse until the perl filehandle is closed.
336		423
337	=cut	424	=cut
338		425
		426	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		427
		428	Seeks the filehandle to the new C<$offset>, similarly to perl's
		429	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		430	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		431	C<IO::AIO::SEEK_END>).
		432
		433	The resulting absolute offset will be passed to the callback, or C<-1> in
		434	case of an error.
		435
		436	In theory, the C<$whence> constants could be different than the
		437	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		438	so don't panic.
		439
		440	As a GNU/Linux (and maybe Solaris) extension, also the constants
		441	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		442	could be found. No guarantees about suitability for use in C<aio_seek> or
		443	Perl's C<sysseek> can be made though, although I would naively assume they
		444	"just work".
		445
339	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	446	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
340		447
341	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	448	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
342		449
343	Reads or writes C<$length> bytes from or to the specified C<$fh> and	450	Reads or writes C<$length> bytes from or to the specified C<$fh> and
344	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>	451	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
345	and calls the callback without the actual number of bytes read (or -1 on	452	calls the callback with the actual number of bytes transferred (or -1 on
346	error, just like the syscall).	453	error, just like the syscall).
347		454
348	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to	455	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
349	offset plus the actual number of bytes read.	456	offset plus the actual number of bytes read.
350		457
…		…
375		482
376	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	483	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
377	reading at byte offset C<$in_offset>, and starts writing at the current	484	reading at byte offset C<$in_offset>, and starts writing at the current
378	file offset of C<$out_fh>. Because of that, it is not safe to issue more	485	file offset of C<$out_fh>. Because of that, it is not safe to issue more
379	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	486	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
380	other.	487	other. The same C<$in_fh> works fine though, as this function does not
		488	move or use the file offset of C<$in_fh>.
381		489
		490	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		491	are written, and there is no way to find out how many more bytes have been
		492	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		493	number of bytes written to C<$out_fh>. Only if the result value equals
		494	C<$length> one can assume that C<$length> bytes have been read.
		495
		496	Unlike with other C<aio_> functions, it makes a lot of sense to use
		497	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		498	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		499	the socket I/O will be non-blocking. Note, however, that you can run
		500	into a trap where C<aio_sendfile> reads some data with readahead, then
		501	fails to write all data, and when the socket is ready the next time, the
		502	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		503	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		504	resource usage.
		505
382	This call tries to make use of a native C<sendfile> syscall to provide	506	This call tries to make use of a native C<sendfile>-like syscall to
383	zero-copy operation. For this to work, C<$out_fh> should refer to a	507	provide zero-copy operation. For this to work, C<$out_fh> should refer to
384	socket, and C<$in_fh> should refer to mmap'able file.	508	a socket, and C<$in_fh> should refer to an mmap'able file.
385		509
386	If a native sendfile cannot be found or it fails with C<ENOSYS>,	510	If a native sendfile cannot be found or it fails with C<ENOSYS>,
387	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,	511	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
388	it will be emulated, so you can call C<aio_sendfile> on any type of	512	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
389	filehandle regardless of the limitations of the operating system.	513	type of filehandle regardless of the limitations of the operating system.
390		514
391	Please note, however, that C<aio_sendfile> can read more bytes from	515	As native sendfile syscalls (as practically any non-POSIX interface hacked
392	C<$in_fh> than are written, and there is no way to find out how many	516	together in a hurry to improve benchmark numbers) tend to be rather buggy
393	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	517	on many systems, this implementation tries to work around some known bugs
394	provides the number of bytes written to C<$out_fh>. Only if the result	518	in Linux and FreeBSD kernels (probably others, too), but that might fail,
395	value equals C<$length> one can assume that C<$length> bytes have been	519	so you really really should check the return value of C<aio_sendfile> -
396	read.	520	fewer bytes than expected might have been transferred.
397		521
398		522
399	=item aio_readahead $fh,$offset,$length, $callback->($retval)	523	=item aio_readahead $fh,$offset,$length, $callback->($retval)
400		524
401	C<aio_readahead> populates the page cache with data from a file so that	525	C<aio_readahead> populates the page cache with data from a file so that
…		…
405	whole pages, so that offset is effectively rounded down to a page boundary	529	whole pages, so that offset is effectively rounded down to a page boundary
406	and bytes are read up to the next page boundary greater than or equal to	530	and bytes are read up to the next page boundary greater than or equal to
407	(off-set+length). C<aio_readahead> does not read beyond the end of the	531	(off-set+length). C<aio_readahead> does not read beyond the end of the
408	file. The current file offset of the file is left unchanged.	532	file. The current file offset of the file is left unchanged.
409		533
410	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	534	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
411	emulated by simply reading the data, which would have a similar effect.	535	be emulated by simply reading the data, which would have a similar effect.
412		536
413		537
414	=item aio_stat $fh_or_path, $callback->($status)	538	=item aio_stat $fh_or_path, $callback->($status)
415		539
416	=item aio_lstat $fh, $callback->($status)	540	=item aio_lstat $fh, $callback->($status)
…		…
423	for an explanation.	547	for an explanation.
424		548
425	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	549	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
426	error when stat'ing a large file, the results will be silently truncated	550	error when stat'ing a large file, the results will be silently truncated
427	unless perl itself is compiled with large file support.	551	unless perl itself is compiled with large file support.
		552
		553	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		554	following constants and functions (if not implemented, the constants will
		555	be C<0> and the functions will either C<croak> or fall back on traditional
		556	behaviour).
		557
		558	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		559	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		560	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
428		561
429	Example: Print the length of F</etc/passwd>:	562	Example: Print the length of F</etc/passwd>:
430		563
431	aio_stat "/etc/passwd", sub {	564	aio_stat "/etc/passwd", sub {
432	$_[0] and die "stat failed: $!";	565	$_[0] and die "stat failed: $!";
433	print "size is ", -s _, "\n";	566	print "size is ", -s _, "\n";
434	};	567	};
435		568
436		569
		570	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		571
		572	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		573	whether a file handle or path was passed.
		574
		575	On success, the callback is passed a hash reference with the following
		576	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		577	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		578	is passed.
		579
		580	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		581	C<ST_NOSUID>.
		582
		583	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		584	their correct value when available, or to C<0> on systems that do
		585	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		586	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		587	C<ST_NODIRATIME> and C<ST_RELATIME>.
		588
		589	Example: stat C</wd> and dump out the data if successful.
		590
		591	aio_statvfs "/wd", sub {
		592	my $f = $_[0]
		593	or die "statvfs: $!";
		594
		595	use Data::Dumper;
		596	say Dumper $f;
		597	};
		598
		599	# result:
		600	{
		601	bsize => 1024,
		602	bfree => 4333064312,
		603	blocks => 10253828096,
		604	files => 2050765568,
		605	flag => 4096,
		606	favail => 2042092649,
		607	bavail => 4333064312,
		608	ffree => 2042092649,
		609	namemax => 255,
		610	frsize => 1024,
		611	fsid => 1810
		612	}
		613
		614	Here is a (likely partial - send me updates!) list of fsid values used by
		615	Linux - it is safe to hardcode these when C<$^O> is C<linux>:
		616
		617	0x0000adf5 adfs
		618	0x0000adff affs
		619	0x5346414f afs
		620	0x09041934 anon-inode filesystem
		621	0x00000187 autofs
		622	0x42465331 befs
		623	0x1badface bfs
		624	0x42494e4d binfmt_misc
		625	0x9123683e btrfs
		626	0x0027e0eb cgroupfs
		627	0xff534d42 cifs
		628	0x73757245 coda
		629	0x012ff7b7 coh
		630	0x28cd3d45 cramfs
		631	0x453dcd28 cramfs-wend (wrong endianness)
		632	0x64626720 debugfs
		633	0x00001373 devfs
		634	0x00001cd1 devpts
		635	0x0000f15f ecryptfs
		636	0x00414a53 efs
		637	0x0000137d ext
		638	0x0000ef53 ext2/ext3/ext4
		639	0x0000ef51 ext2
		640	0xf2f52010 f2fs
		641	0x00004006 fat
		642	0x65735546 fuseblk
		643	0x65735543 fusectl
		644	0x0bad1dea futexfs
		645	0x01161970 gfs2
		646	0x47504653 gpfs
		647	0x00004244 hfs
		648	0xf995e849 hpfs
		649	0x00c0ffee hostfs
		650	0x958458f6 hugetlbfs
		651	0x2bad1dea inotifyfs
		652	0x00009660 isofs
		653	0x000072b6 jffs2
		654	0x3153464a jfs
		655	0x6b414653 k-afs
		656	0x0bd00bd0 lustre
		657	0x0000137f minix
		658	0x0000138f minix 30 char names
		659	0x00002468 minix v2
		660	0x00002478 minix v2 30 char names
		661	0x00004d5a minix v3
		662	0x19800202 mqueue
		663	0x00004d44 msdos
		664	0x0000564c novell
		665	0x00006969 nfs
		666	0x6e667364 nfsd
		667	0x00003434 nilfs
		668	0x5346544e ntfs
		669	0x00009fa1 openprom
		670	0x7461636F ocfs2
		671	0x00009fa0 proc
		672	0x6165676c pstorefs
		673	0x0000002f qnx4
		674	0x68191122 qnx6
		675	0x858458f6 ramfs
		676	0x52654973 reiserfs
		677	0x00007275 romfs
		678	0x67596969 rpc_pipefs
		679	0x73636673 securityfs
		680	0xf97cff8c selinux
		681	0x0000517b smb
		682	0x534f434b sockfs
		683	0x73717368 squashfs
		684	0x62656572 sysfs
		685	0x012ff7b6 sysv2
		686	0x012ff7b5 sysv4
		687	0x01021994 tmpfs
		688	0x15013346 udf
		689	0x00011954 ufs
		690	0x54190100 ufs byteswapped
		691	0x00009fa2 usbdevfs
		692	0x01021997 v9fs
		693	0xa501fcf5 vxfs
		694	0xabba1974 xenfs
		695	0x012ff7b4 xenix
		696	0x58465342 xfs
		697	0x012fd16d xia
		698
437	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	699	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
438		700
439	Works like perl's C<utime> function (including the special case of $atime	701	Works like perl's C<utime> function (including the special case of $atime
440	and $mtime being undef). Fractional times are supported if the underlying	702	and $mtime being undef). Fractional times are supported if the underlying
441	syscalls support them.	703	syscalls support them.
…		…
468	=item aio_truncate $fh_or_path, $offset, $callback->($status)	730	=item aio_truncate $fh_or_path, $offset, $callback->($status)
469		731
470	Works like truncate(2) or ftruncate(2).	732	Works like truncate(2) or ftruncate(2).
471		733
472		734
		735	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		736
		737	Allocates or frees disk space according to the C<$mode> argument. See the
		738	linux C<fallocate> documentation for details.
		739
		740	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		741	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		742	to deallocate a file range.
		743
		744	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		745	(without leaving a hole) and C<FALLOC_FL_ZERO_RANGE>, to zero a range (see
		746	your L<fallocate(2)> manpage).
		747
		748	The file system block size used by C<fallocate> is presumably the
		749	C<f_bsize> returned by C<statvfs>.
		750
		751	If C<fallocate> isn't available or cannot be emulated (currently no
		752	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		753
		754
473	=item aio_chmod $fh_or_path, $mode, $callback->($status)	755	=item aio_chmod $fh_or_path, $mode, $callback->($status)
474		756
475	Works like perl's C<chmod> function.	757	Works like perl's C<chmod> function.
476		758
477		759
…		…
479		761
480	Asynchronously unlink (delete) a file and call the callback with the	762	Asynchronously unlink (delete) a file and call the callback with the
481	result code.	763	result code.
482		764
483		765
484	=item aio_mknod $path, $mode, $dev, $callback->($status)	766	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
485		767
486	[EXPERIMENTAL]	768	[EXPERIMENTAL]
487		769
488	Asynchronously create a device node (or fifo). See mknod(2).	770	Asynchronously create a device node (or fifo). See mknod(2).
489		771
490	The only (POSIX-) portable way of calling this function is:	772	The only (POSIX-) portable way of calling this function is:
491		773
492	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	774	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
493		775
		776	See C<aio_stat> for info about some potentially helpful extra constants
		777	and functions.
494		778
495	=item aio_link $srcpath, $dstpath, $callback->($status)	779	=item aio_link $srcpath, $dstpath, $callback->($status)
496		780
497	Asynchronously create a new link to the existing object at C<$srcpath> at	781	Asynchronously create a new link to the existing object at C<$srcpath> at
498	the path C<$dstpath> and call the callback with the result code.	782	the path C<$dstpath> and call the callback with the result code.
…		…
502		786
503	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	787	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
504	the path C<$dstpath> and call the callback with the result code.	788	the path C<$dstpath> and call the callback with the result code.
505		789
506		790
507	=item aio_readlink $path, $callback->($link)	791	=item aio_readlink $pathname, $callback->($link)
508		792
509	Asynchronously read the symlink specified by C<$path> and pass it to	793	Asynchronously read the symlink specified by C<$path> and pass it to
510	the callback. If an error occurs, nothing or undef gets passed to the	794	the callback. If an error occurs, nothing or undef gets passed to the
511	callback.	795	callback.
512		796
513		797
		798	=item aio_realpath $pathname, $callback->($path)
		799
		800	Asynchronously make the path absolute and resolve any symlinks in
		801	C<$path>. The resulting path only consists of directories (same as
		802	L<Cwd::realpath>).
		803
		804	This request can be used to get the absolute path of the current working
		805	directory by passing it a path of F<.> (a single dot).
		806
		807
514	=item aio_rename $srcpath, $dstpath, $callback->($status)	808	=item aio_rename $srcpath, $dstpath, $callback->($status)
515		809
516	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	810	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
517	rename(2) and call the callback with the result code.	811	rename(2) and call the callback with the result code.
		812
		813	On systems that support the AIO::WD working directory abstraction
		814	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		815	of failing, C<rename> is called on the absolute path of C<$wd>.
		816
		817
		818	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		819
		820	Basically a version of C<aio_rename> with an additional C<$flags>
		821	argument. Calling this with C<$flags=0> is the same as calling
		822	C<aio_rename>.
		823
		824	Non-zero flags are currently only supported on GNU/Linux systems that
		825	support renameat2. Other systems fail with C<ENOSYS> in this case.
		826
		827	The following constants are available (missing ones are, as usual C<0>),
		828	see renameat2(2) for details:
		829
		830	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		831	and C<IO::AIO::RENAME_WHITEOUT>.
518		832
519		833
520	=item aio_mkdir $pathname, $mode, $callback->($status)	834	=item aio_mkdir $pathname, $mode, $callback->($status)
521		835
522	Asynchronously mkdir (create) a directory and call the callback with	836	Asynchronously mkdir (create) a directory and call the callback with
…		…
527	=item aio_rmdir $pathname, $callback->($status)	841	=item aio_rmdir $pathname, $callback->($status)
528		842
529	Asynchronously rmdir (delete) a directory and call the callback with the	843	Asynchronously rmdir (delete) a directory and call the callback with the
530	result code.	844	result code.
531		845
		846	On systems that support the AIO::WD working directory abstraction
		847	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		848	C<rmdir> is called on the absolute path of C<$wd>.
		849
532		850
533	=item aio_readdir $pathname, $callback->($entries)	851	=item aio_readdir $pathname, $callback->($entries)
534		852
535	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	853	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
536	directory (i.e. opendir + readdir + closedir). The entries will not be	854	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
540	array-ref with the filenames.	858	array-ref with the filenames.
541		859
542		860
543	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	861	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
544		862
545	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	863	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
546	behaviour and output format. In case of an error, C<$entries> will be	864	tune behaviour and output format. In case of an error, C<$entries> will be
547	C<undef>.	865	C<undef>.
548		866
549	The flags are a combination of the following constants, ORed together (the	867	The flags are a combination of the following constants, ORed together (the
550	flags will also be passed to the callback, possibly modified):	868	flags will also be passed to the callback, possibly modified):
551		869
552	=over 4	870	=over 4
553		871
554	=item IO::AIO::READDIR_DENTS	872	=item IO::AIO::READDIR_DENTS
555		873
556	When this flag is off, then the callback gets an arrayref with of names	874	When this flag is off, then the callback gets an arrayref consisting of
557	only (as with C<aio_readdir>), otherwise it gets an arrayref with	875	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
558	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	876	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
559	entry in more detail.	877	entry in more detail.
560		878
561	C<$name> is the name of the entry.	879	C<$name> is the name of the entry.
562		880
…		…
575	systems that do not deliver the inode information.	893	systems that do not deliver the inode information.
576		894
577	=item IO::AIO::READDIR_DIRS_FIRST	895	=item IO::AIO::READDIR_DIRS_FIRST
578		896
579	When this flag is set, then the names will be returned in an order where	897	When this flag is set, then the names will be returned in an order where
580	likely directories come first. This is useful when you need to quickly	898	likely directories come first, in optimal stat order. This is useful when
581	find directories, or you want to find all directories while avoiding to	899	you need to quickly find directories, or you want to find all directories
582	stat() each entry.	900	while avoiding to stat() each entry.
583		901
584	If the system returns type information in readdir, then this is used	902	If the system returns type information in readdir, then this is used
585	to find directories directly. Otherwise, likely directories are files	903	to find directories directly. Otherwise, likely directories are names
586	beginning with ".", or otherwise files with no dots, of which files with	904	beginning with ".", or otherwise names with no dots, of which names with
587	short names are tried first.	905	short names are tried first.
588		906
589	=item IO::AIO::READDIR_STAT_ORDER	907	=item IO::AIO::READDIR_STAT_ORDER
590		908
591	When this flag is set, then the names will be returned in an order	909	When this flag is set, then the names will be returned in an order
…		…
598		916
599	=item IO::AIO::READDIR_FOUND_UNKNOWN	917	=item IO::AIO::READDIR_FOUND_UNKNOWN
600		918
601	This flag should not be set when calling C<aio_readdirx>. Instead, it	919	This flag should not be set when calling C<aio_readdirx>. Instead, it
602	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	920	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
603	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	921	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
604	C<$type>'s are known, which can be used to speed up some algorithms.	922	C<$type>'s are known, which can be used to speed up some algorithms.
605		923
606	=back	924	=back
607		925
608		926
609	=item aio_load $path, $data, $callback->($status)	927	=item aio_load $pathname, $data, $callback->($status)
610		928
611	This is a composite request that tries to fully load the given file into	929	This is a composite request that tries to fully load the given file into
612	memory. Status is the same as with aio_read.	930	memory. Status is the same as with aio_read.
613		931
614	=cut	932	=cut
…		…
736	if ($_[0] && $! == EXDEV) {	1054	if ($_[0] && $! == EXDEV) {
737	aioreq_pri $pri;	1055	aioreq_pri $pri;
738	add $grp aio_copy $src, $dst, sub {	1056	add $grp aio_copy $src, $dst, sub {
739	$grp->result ($_[0]);	1057	$grp->result ($_[0]);
740		1058
741	if (!$_[0]) {	1059	unless ($_[0]) {
742	aioreq_pri $pri;	1060	aioreq_pri $pri;
743	add $grp aio_unlink $src;	1061	add $grp aio_unlink $src;
744	}	1062	}
745	};	1063	};
746	} else {	1064	} else {
…		…
749	};	1067	};
750		1068
751	$grp	1069	$grp
752	}	1070	}
753		1071
754	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1072	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
755		1073
756	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1074	Scans a directory (similar to C<aio_readdir>) but additionally tries to
757	efficiently separate the entries of directory C<$path> into two sets of	1075	efficiently separate the entries of directory C<$path> into two sets of
758	names, directories you can recurse into (directories), and ones you cannot	1076	names, directories you can recurse into (directories), and ones you cannot
759	recurse into (everything else, including symlinks to directories).	1077	recurse into (everything else, including symlinks to directories).
…		…
790	Then entries will be sorted into likely directories a non-initial dot	1108	Then entries will be sorted into likely directories a non-initial dot
791	currently) and likely non-directories (see C<aio_readdirx>). Then every	1109	currently) and likely non-directories (see C<aio_readdirx>). Then every
792	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1110	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
793	in order of their inode numbers. If that succeeds, it assumes that the	1111	in order of their inode numbers. If that succeeds, it assumes that the
794	entry is a directory or a symlink to directory (which will be checked	1112	entry is a directory or a symlink to directory (which will be checked
795	seperately). This is often faster than stat'ing the entry itself because	1113	separately). This is often faster than stat'ing the entry itself because
796	filesystems might detect the type of the entry without reading the inode	1114	filesystems might detect the type of the entry without reading the inode
797	data (e.g. ext2fs filetype feature), even on systems that cannot return	1115	data (e.g. ext2fs filetype feature), even on systems that cannot return
798	the filetype information on readdir.	1116	the filetype information on readdir.
799		1117
800	If the known number of directories (link count - 2) has been reached, the	1118	If the known number of directories (link count - 2) has been reached, the
…		…
816		1134
817	my $grp = aio_group $cb;	1135	my $grp = aio_group $cb;
818		1136
819	$maxreq = 4 if $maxreq <= 0;	1137	$maxreq = 4 if $maxreq <= 0;
820		1138
821	# stat once	1139	# get a wd object
822	aioreq_pri $pri;	1140	aioreq_pri $pri;
823	add $grp aio_stat $path, sub {	1141	add $grp aio_wd $path, sub {
		1142	$_[0]
824	return $grp->result () if $_[0];	1143	or return $grp->result ();
825	my $now = time;
826	my $hash1 = join ":", (stat _)[0,1,3,7,9];
827		1144
828	# read the directory entries	1145	my $wd = [shift, "."];
		1146
		1147	# stat once
829	aioreq_pri $pri;	1148	aioreq_pri $pri;
830	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1149	add $grp aio_stat $wd, sub {
831	my $entries = shift
832	or return $grp->result ();	1150	return $grp->result () if $_[0];
		1151	my $now = time;
		1152	my $hash1 = join ":", (stat _)[0,1,3,7,9];
833		1153
834	# stat the dir another time	1154	# read the directory entries
835	aioreq_pri $pri;	1155	aioreq_pri $pri;
		1156	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1157	my $entries = shift
		1158	or return $grp->result ();
		1159
		1160	# stat the dir another time
		1161	aioreq_pri $pri;
836	add $grp aio_stat $path, sub {	1162	add $grp aio_stat $wd, sub {
837	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1163	my $hash2 = join ":", (stat _)[0,1,3,7,9];
838		1164
839	my $ndirs;	1165	my $ndirs;
840		1166
841	# take the slow route if anything looks fishy	1167	# take the slow route if anything looks fishy
842	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1168	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
843	$ndirs = -1;	1169	$ndirs = -1;
844	} else {	1170	} else {
845	# if nlink == 2, we are finished	1171	# if nlink == 2, we are finished
846	# for non-posix-fs's, we rely on nlink < 2	1172	# for non-posix-fs's, we rely on nlink < 2
847	$ndirs = (stat _)[3] - 2	1173	$ndirs = (stat _)[3] - 2
848	or return $grp->result ([], $entries);	1174	or return $grp->result ([], $entries);
849	}	1175	}
850		1176
851	my (@dirs, @nondirs);	1177	my (@dirs, @nondirs);
852		1178
853	my $statgrp = add $grp aio_group sub {	1179	my $statgrp = add $grp aio_group sub {
854	$grp->result (\@dirs, \@nondirs);	1180	$grp->result (\@dirs, \@nondirs);
855	};	1181	};
856		1182
857	limit $statgrp $maxreq;	1183	limit $statgrp $maxreq;
858	feed $statgrp sub {	1184	feed $statgrp sub {
859	return unless @$entries;	1185	return unless @$entries;
860	my $entry = shift @$entries;	1186	my $entry = shift @$entries;
861		1187
862	aioreq_pri $pri;	1188	aioreq_pri $pri;
		1189	$wd->[1] = "$entry/.";
863	add $statgrp aio_stat "$path/$entry/.", sub {	1190	add $statgrp aio_stat $wd, sub {
864	if ($_[0] < 0) {	1191	if ($_[0] < 0) {
865	push @nondirs, $entry;	1192	push @nondirs, $entry;
866	} else {	1193	} else {
867	# need to check for real directory	1194	# need to check for real directory
868	aioreq_pri $pri;	1195	aioreq_pri $pri;
		1196	$wd->[1] = $entry;
869	add $statgrp aio_lstat "$path/$entry", sub {	1197	add $statgrp aio_lstat $wd, sub {
870	if (-d _) {	1198	if (-d _) {
871	push @dirs, $entry;	1199	push @dirs, $entry;
872		1200
873	unless (--$ndirs) {	1201	unless (--$ndirs) {
874	push @nondirs, @$entries;	1202	push @nondirs, @$entries;
875	feed $statgrp;	1203	feed $statgrp;
		1204	}
		1205	} else {
		1206	push @nondirs, $entry;
876	}	1207	}
877	} else {
878	push @nondirs, $entry;
879	}	1208	}
880	}	1209	}
881	}	1210	};
882	};	1211	};
883	};	1212	};
884	};	1213	};
885	};	1214	};
886	};	1215	};
887		1216
888	$grp	1217	$grp
889	}	1218	}
890		1219
891	=item aio_rmtree $path, $callback->($status)	1220	=item aio_rmtree $pathname, $callback->($status)
892		1221
893	Delete a directory tree starting (and including) C<$path>, return the	1222	Delete a directory tree starting (and including) C<$path>, return the
894	status of the final C<rmdir> only. This is a composite request that	1223	status of the final C<rmdir> only. This is a composite request that
895	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1224	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
896	everything else.	1225	everything else.
897		1226
898	=cut	1227	=cut
899		1228
…		…
921	};	1250	};
922		1251
923	$grp	1252	$grp
924	}	1253	}
925		1254
		1255	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1256
		1257	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1258
		1259	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1260	they execute asynchronously and pass the return value to the callback.
		1261
		1262	Both calls can be used for a lot of things, some of which make more sense
		1263	to run asynchronously in their own thread, while some others make less
		1264	sense. For example, calls that block waiting for external events, such
		1265	as locking, will also lock down an I/O thread while it is waiting, which
		1266	can deadlock the whole I/O system. At the same time, there might be no
		1267	alternative to using a thread to wait.
		1268
		1269	So in general, you should only use these calls for things that do
		1270	(filesystem) I/O, not for things that wait for other events (network,
		1271	other processes), although if you are careful and know what you are doing,
		1272	you still can.
		1273
		1274	The following constants are available (missing ones are, as usual C<0>):
		1275
		1276	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1277
		1278	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1279	C<FS_IOC_FIEMAP>.
		1280
		1281	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1282	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1283
		1284	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1285	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1286	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1287	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1288	C<FS_FL_USER_MODIFIABLE>.
		1289
		1290	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1291	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1292	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1293	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1294
926	=item aio_sync $callback->($status)	1295	=item aio_sync $callback->($status)
927		1296
928	Asynchronously call sync and call the callback when finished.	1297	Asynchronously call sync and call the callback when finished.
929		1298
930	=item aio_fsync $fh, $callback->($status)	1299	=item aio_fsync $fh, $callback->($status)
…		…
937	Asynchronously call fdatasync on the given filehandle and call the	1306	Asynchronously call fdatasync on the given filehandle and call the
938	callback with the fdatasync result code.	1307	callback with the fdatasync result code.
939		1308
940	If this call isn't available because your OS lacks it or it couldn't be	1309	If this call isn't available because your OS lacks it or it couldn't be
941	detected, it will be emulated by calling C<fsync> instead.	1310	detected, it will be emulated by calling C<fsync> instead.
		1311
		1312	=item aio_syncfs $fh, $callback->($status)
		1313
		1314	Asynchronously call the syncfs syscall to sync the filesystem associated
		1315	to the given filehandle and call the callback with the syncfs result
		1316	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1317	errno to C<ENOSYS> nevertheless.
942		1318
943	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1319	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
944		1320
945	Sync the data portion of the file specified by C<$offset> and C<$length>	1321	Sync the data portion of the file specified by C<$offset> and C<$length>
946	to disk (but NOT the metadata), by calling the Linux-specific	1322	to disk (but NOT the metadata), by calling the Linux-specific
…		…
950	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1326	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
951	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1327	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
952	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1328	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
953	manpage for details.	1329	manpage for details.
954		1330
955	=item aio_pathsync $path, $callback->($status)	1331	=item aio_pathsync $pathname, $callback->($status)
956		1332
957	This request tries to open, fsync and close the given path. This is a	1333	This request tries to open, fsync and close the given path. This is a
958	composite request intended to sync directories after directory operations	1334	composite request intended to sync directories after directory operations
959	(E.g. rename). This might not work on all operating systems or have any	1335	(E.g. rename). This might not work on all operating systems or have any
960	specific effect, but usually it makes sure that directory changes get	1336	specific effect, but usually it makes sure that directory changes get
…		…
991	};	1367	};
992		1368
993	$grp	1369	$grp
994	}	1370	}
995		1371
996	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1372	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
997		1373
998	This is a rather advanced IO::AIO call, which only works on mmap(2)ed	1374	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
999	scalars (see the L<Sys::Mmap> or L<Mmap> modules for details on this, note	1375	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1376	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
1000	that the scalar must only be modified in-place while an aio operation is	1377	scalar must only be modified in-place while an aio operation is pending on
1001	pending on it).	1378	it).
1002		1379
1003	It calls the C<msync> function of your OS, if available, with the memory	1380	It calls the C<msync> function of your OS, if available, with the memory
1004	area starting at C<$offset> in the string and ending C<$length> bytes	1381	area starting at C<$offset> in the string and ending C<$length> bytes
1005	later. If C<$length> is negative, counts from the end, and if C<$length>	1382	later. If C<$length> is negative, counts from the end, and if C<$length>
1006	is C<undef>, then it goes till the end of the string. The flags can be	1383	is C<undef>, then it goes till the end of the string. The flags can be
1007	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and	1384	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
1008	C<IO::AIO::MS_SYNC>.	1385	C<IO::AIO::MS_INVALIDATE>.
1009		1386
1010	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	1387	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
1011		1388
1012	This is a rather advanced IO::AIO call, which works best on mmap(2)ed	1389	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
1013	scalars.	1390	scalars.
1014		1391
1015	It touches (reads or writes) all memory pages in the specified	1392	It touches (reads or writes) all memory pages in the specified
1016	range inside the scalar. All caveats and parameters are the same	1393	range inside the scalar. All caveats and parameters are the same
1017	as for C<aio_msync>, above, except for flags, which must be either	1394	as for C<aio_msync>, above, except for flags, which must be either
1018	C<0> (which reads all pages and ensures they are instantiated) or	1395	C<0> (which reads all pages and ensures they are instantiated) or
1019	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and	1396	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
1020	writing an octet from it, which dirties the page).	1397	writing an octet from it, which dirties the page).
		1398
		1399	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1400
		1401	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1402	scalars.
		1403
		1404	It reads in all the pages of the underlying storage into memory (if any)
		1405	and locks them, so they are not getting swapped/paged out or removed.
		1406
		1407	If C<$length> is undefined, then the scalar will be locked till the end.
		1408
		1409	On systems that do not implement C<mlock>, this function returns C<-1>
		1410	and sets errno to C<ENOSYS>.
		1411
		1412	Note that the corresponding C<munlock> is synchronous and is
		1413	documented under L<MISCELLANEOUS FUNCTIONS>.
		1414
		1415	Example: open a file, mmap and mlock it - both will be undone when
		1416	C<$data> gets destroyed.
		1417
		1418	open my $fh, "<", $path or die "$path: $!";
		1419	my $data;
		1420	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1421	aio_mlock $data; # mlock in background
		1422
		1423	=item aio_mlockall $flags, $callback->($status)
		1424
		1425	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1426	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1427
		1428	On systems that do not implement C<mlockall>, this function returns C<-1>
		1429	and sets errno to C<ENOSYS>.
		1430
		1431	Note that the corresponding C<munlockall> is synchronous and is
		1432	documented under L<MISCELLANEOUS FUNCTIONS>.
		1433
		1434	Example: asynchronously lock all current and future pages into memory.
		1435
		1436	aio_mlockall IO::AIO::MCL_FUTURE;
		1437
		1438	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1439
		1440	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1441	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1442	the ioctl is not available on your OS, then this request will fail with
		1443	C<ENOSYS>.
		1444
		1445	C<$start> is the starting offset to query extents for, C<$length> is the
		1446	size of the range to query - if it is C<undef>, then the whole file will
		1447	be queried.
		1448
		1449	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1450	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1451	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1452	the data portion.
		1453
		1454	C<$count> is the maximum number of extent records to return. If it is
		1455	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1456	case, if it is C<0>, then the callback receives the number of extents
		1457	instead of the extents themselves (which is unreliable, see below).
		1458
		1459	If an error occurs, the callback receives no arguments. The special
		1460	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1461
		1462	Otherwise, the callback receives an array reference with extent
		1463	structures. Each extent structure is an array reference itself, with the
		1464	following members:
		1465
		1466	[$logical, $physical, $length, $flags]
		1467
		1468	Flags is any combination of the following flag values (typically either C<0>
		1469	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1470
		1471	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1472	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1473	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1474	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1475	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1476	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1477
		1478	At the time of this writing (Linux 3.2), this requets is unreliable unless
		1479	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1480	it to return all extents of a range for files with large number of
		1481	extents. The code works around all these issues if C<$count> is undef.
1021		1482
1022	=item aio_group $callback->(...)	1483	=item aio_group $callback->(...)
1023		1484
1024	This is a very special aio request: Instead of doing something, it is a	1485	This is a very special aio request: Instead of doing something, it is a
1025	container for other aio requests, which is useful if you want to bundle	1486	container for other aio requests, which is useful if you want to bundle
…		…
1062	like sleep and file handle readable/writable, the overhead this creates is	1523	like sleep and file handle readable/writable, the overhead this creates is
1063	immense (it blocks a thread for a long time) so do not use this function	1524	immense (it blocks a thread for a long time) so do not use this function
1064	except to put your application under artificial I/O pressure.	1525	except to put your application under artificial I/O pressure.
1065		1526
1066	=back	1527	=back
		1528
		1529
		1530	=head2 IO::AIO::WD - multiple working directories
		1531
		1532	Your process only has one current working directory, which is used by all
		1533	threads. This makes it hard to use relative paths (some other component
		1534	could call C<chdir> at any time, and it is hard to control when the path
		1535	will be used by IO::AIO).
		1536
		1537	One solution for this is to always use absolute paths. This usually works,
		1538	but can be quite slow (the kernel has to walk the whole path on every
		1539	access), and can also be a hassle to implement.
		1540
		1541	Newer POSIX systems have a number of functions (openat, fdopendir,
		1542	futimensat and so on) that make it possible to specify working directories
		1543	per operation.
		1544
		1545	For portability, and because the clowns who "designed", or shall I write,
		1546	perpetrated this new interface were obviously half-drunk, this abstraction
		1547	cannot be perfect, though.
		1548
		1549	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1550	object. This object stores the canonicalised, absolute version of the
		1551	path, and on systems that allow it, also a directory file descriptor.
		1552
		1553	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1554	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1555	object and a pathname instead (or the IO::AIO::WD object alone, which
		1556	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1557	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1558	to that IO::AIO::WD object.
		1559
		1560	For example, to get a wd object for F</etc> and then stat F<passwd>
		1561	inside, you would write:
		1562
		1563	aio_wd "/etc", sub {
		1564	my $etcdir = shift;
		1565
		1566	# although $etcdir can be undef on error, there is generally no reason
		1567	# to check for errors here, as aio_stat will fail with ENOENT
		1568	# when $etcdir is undef.
		1569
		1570	aio_stat [$etcdir, "passwd"], sub {
		1571	# yay
		1572	};
		1573	};
		1574
		1575	The fact that C<aio_wd> is a request and not a normal function shows that
		1576	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1577	which is why it is done asynchronously.
		1578
		1579	To stat the directory obtained with C<aio_wd> above, one could write
		1580	either of the following three request calls:
		1581
		1582	aio_lstat "/etc" , sub { ... # pathname as normal string
		1583	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1584	aio_lstat $wd , sub { ... # shorthand for the previous
		1585
		1586	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1587	object and the pathname string, so you could write the following without
		1588	causing any issues due to C<$path> getting reused:
		1589
		1590	my $path = [$wd, undef];
		1591
		1592	for my $name (qw(abc def ghi)) {
		1593	$path->[1] = $name;
		1594	aio_stat $path, sub {
		1595	# ...
		1596	};
		1597	}
		1598
		1599	There are some caveats: when directories get renamed (or deleted), the
		1600	pathname string doesn't change, so will point to the new directory (or
		1601	nowhere at all), while the directory fd, if available on the system,
		1602	will still point to the original directory. Most functions accepting a
		1603	pathname will use the directory fd on newer systems, and the string on
		1604	older systems. Some functions (such as realpath) will always rely on the
		1605	string form of the pathname.
		1606
		1607	So this functionality is mainly useful to get some protection against
		1608	C<chdir>, to easily get an absolute path out of a relative path for future
		1609	reference, and to speed up doing many operations in the same directory
		1610	(e.g. when stat'ing all files in a directory).
		1611
		1612	The following functions implement this working directory abstraction:
		1613
		1614	=over 4
		1615
		1616	=item aio_wd $pathname, $callback->($wd)
		1617
		1618	Asynchonously canonicalise the given pathname and convert it to an
		1619	IO::AIO::WD object representing it. If possible and supported on the
		1620	system, also open a directory fd to speed up pathname resolution relative
		1621	to this working directory.
		1622
		1623	If something goes wrong, then C<undef> is passwd to the callback instead
		1624	of a working directory object and C<$!> is set appropriately. Since
		1625	passing C<undef> as working directory component of a pathname fails the
		1626	request with C<ENOENT>, there is often no need for error checking in the
		1627	C<aio_wd> callback, as future requests using the value will fail in the
		1628	expected way.
		1629
		1630	=item IO::AIO::CWD
		1631
		1632	This is a compiletime constant (object) that represents the process
		1633	current working directory.
		1634
		1635	Specifying this object as working directory object for a pathname is as if
		1636	the pathname would be specified directly, without a directory object. For
		1637	example, these calls are functionally identical:
		1638
		1639	aio_stat "somefile", sub { ... };
		1640	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1641
		1642	=back
		1643
		1644	To recover the path associated with an IO::AIO::WD object, you can use
		1645	C<aio_realpath>:
		1646
		1647	aio_realpath $wd, sub {
		1648	warn "path is $_[0]\n";
		1649	};
		1650
		1651	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1652	sometimes, fall back to using an absolue path.
1067		1653
1068	=head2 IO::AIO::REQ CLASS	1654	=head2 IO::AIO::REQ CLASS
1069		1655
1070	All non-aggregate C<aio_*> functions return an object of this class when	1656	All non-aggregate C<aio_*> functions return an object of this class when
1071	called in non-void context.	1657	called in non-void context.
…		…
1189		1775
1190	Sets a feeder/generator on this group: every group can have an attached	1776	Sets a feeder/generator on this group: every group can have an attached
1191	generator that generates requests if idle. The idea behind this is that,	1777	generator that generates requests if idle. The idea behind this is that,
1192	although you could just queue as many requests as you want in a group,	1778	although you could just queue as many requests as you want in a group,
1193	this might starve other requests for a potentially long time. For example,	1779	this might starve other requests for a potentially long time. For example,
1194	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1780	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1195	delaying any later requests for a long time.	1781	requests, delaying any later requests for a long time.
1196		1782
1197	To avoid this, and allow incremental generation of requests, you can	1783	To avoid this, and allow incremental generation of requests, you can
1198	instead a group and set a feeder on it that generates those requests. The	1784	instead a group and set a feeder on it that generates those requests. The
1199	feed callback will be called whenever there are few enough (see C<limit>,	1785	feed callback will be called whenever there are few enough (see C<limit>,
1200	below) requests active in the group itself and is expected to queue more	1786	below) requests active in the group itself and is expected to queue more
…		…
1249		1835
1250	See C<poll_cb> for an example.	1836	See C<poll_cb> for an example.
1251		1837
1252	=item IO::AIO::poll_cb	1838	=item IO::AIO::poll_cb
1253		1839
1254	Process some outstanding events on the result pipe. You have to call this	1840	Process some requests that have reached the result phase (i.e. they have
1255	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1841	been executed but the results are not yet reported). You have to call
1256	returned earlier for whatever reason. Returns immediately when no events	1842	this "regularly" to finish outstanding requests.
1257	are outstanding. The amount of events processed depends on the settings of
1258	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1259		1843
		1844	Returns C<0> if all events could be processed (or there were no
		1845	events to process), or C<-1> if it returned earlier for whatever
		1846	reason. Returns immediately when no events are outstanding. The amount
		1847	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
		1848	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
		1849
1260	If not all requests were processed for whatever reason, the filehandle	1850	If not all requests were processed for whatever reason, the poll file
1261	will still be ready when C<poll_cb> returns, so normally you don't have to	1851	descriptor will still be ready when C<poll_cb> returns, so normally you
1262	do anything special to have it called later.	1852	don't have to do anything special to have it called later.
		1853
		1854	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1855	ready, it can be beneficial to call this function from loops which submit
		1856	a lot of requests, to make sure the results get processed when they become
		1857	available and not just when the loop is finished and the event loop takes
		1858	over again. This function returns very fast when there are no outstanding
		1859	requests.
1263		1860
1264	Example: Install an Event watcher that automatically calls	1861	Example: Install an Event watcher that automatically calls
1265	IO::AIO::poll_cb with high priority (more examples can be found in the	1862	IO::AIO::poll_cb with high priority (more examples can be found in the
1266	SYNOPSIS section, at the top of this document):	1863	SYNOPSIS section, at the top of this document):
1267		1864
1268	Event->io (fd => IO::AIO::poll_fileno,	1865	Event->io (fd => IO::AIO::poll_fileno,
1269	poll => 'r', async => 1,	1866	poll => 'r', async => 1,
1270	cb => \&IO::AIO::poll_cb);	1867	cb => \&IO::AIO::poll_cb);
		1868
		1869	=item IO::AIO::poll_wait
		1870
		1871	Wait until either at least one request is in the result phase or no
		1872	requests are outstanding anymore.
		1873
		1874	This is useful if you want to synchronously wait for some requests to
		1875	become ready, without actually handling them.
		1876
		1877	See C<nreqs> for an example.
		1878
		1879	=item IO::AIO::poll
		1880
		1881	Waits until some requests have been handled.
		1882
		1883	Returns the number of requests processed, but is otherwise strictly
		1884	equivalent to:
		1885
		1886	IO::AIO::poll_wait, IO::AIO::poll_cb
		1887
		1888	=item IO::AIO::flush
		1889
		1890	Wait till all outstanding AIO requests have been handled.
		1891
		1892	Strictly equivalent to:
		1893
		1894	IO::AIO::poll_wait, IO::AIO::poll_cb
		1895	while IO::AIO::nreqs;
1271		1896
1272	=item IO::AIO::max_poll_reqs $nreqs	1897	=item IO::AIO::max_poll_reqs $nreqs
1273		1898
1274	=item IO::AIO::max_poll_time $seconds	1899	=item IO::AIO::max_poll_time $seconds
1275		1900
…		…
1300	# use a low priority so other tasks have priority	1925	# use a low priority so other tasks have priority
1301	Event->io (fd => IO::AIO::poll_fileno,	1926	Event->io (fd => IO::AIO::poll_fileno,
1302	poll => 'r', nice => 1,	1927	poll => 'r', nice => 1,
1303	cb => &IO::AIO::poll_cb);	1928	cb => &IO::AIO::poll_cb);
1304		1929
1305	=item IO::AIO::poll_wait
1306
1307	If there are any outstanding requests and none of them in the result
1308	phase, wait till the result filehandle becomes ready for reading (simply
1309	does a C<select> on the filehandle. This is useful if you want to
1310	synchronously wait for some requests to finish).
1311
1312	See C<nreqs> for an example.
1313
1314	=item IO::AIO::poll
1315
1316	Waits until some requests have been handled.
1317
1318	Returns the number of requests processed, but is otherwise strictly
1319	equivalent to:
1320
1321	IO::AIO::poll_wait, IO::AIO::poll_cb
1322
1323	=item IO::AIO::flush
1324
1325	Wait till all outstanding AIO requests have been handled.
1326
1327	Strictly equivalent to:
1328
1329	IO::AIO::poll_wait, IO::AIO::poll_cb
1330	while IO::AIO::nreqs;
1331
1332	=back	1930	=back
1333		1931
1334	=head3 CONTROLLING THE NUMBER OF THREADS	1932	=head3 CONTROLLING THE NUMBER OF THREADS
1335		1933
1336	=over	1934	=over
…		…
1369		1967
1370	Under normal circumstances you don't need to call this function.	1968	Under normal circumstances you don't need to call this function.
1371		1969
1372	=item IO::AIO::max_idle $nthreads	1970	=item IO::AIO::max_idle $nthreads
1373		1971
1374	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1972	Limit the number of threads (default: 4) that are allowed to idle
1375	threads that did not get a request to process within 10 seconds). That	1973	(i.e., threads that did not get a request to process within the idle
1376	means if a thread becomes idle while C<$nthreads> other threads are also	1974	timeout (default: 10 seconds). That means if a thread becomes idle while
1377	idle, it will free its resources and exit.	1975	C<$nthreads> other threads are also idle, it will free its resources and
		1976	exit.
1378		1977
1379	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1978	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1380	to allow for extremely high load situations, but want to free resources	1979	to allow for extremely high load situations, but want to free resources
1381	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1980	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1382		1981
1383	The default is probably ok in most situations, especially if thread	1982	The default is probably ok in most situations, especially if thread
1384	creation is fast. If thread creation is very slow on your system you might	1983	creation is fast. If thread creation is very slow on your system you might
1385	want to use larger values.	1984	want to use larger values.
1386		1985
		1986	=item IO::AIO::idle_timeout $seconds
		1987
		1988	Sets the minimum idle timeout (default 10) after which worker threads are
		1989	allowed to exit. SEe C<IO::AIO::max_idle>.
		1990
1387	=item IO::AIO::max_outstanding $maxreqs	1991	=item IO::AIO::max_outstanding $maxreqs
		1992
		1993	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1994	you do queue up more than this number of requests, the next call to
		1995	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1996	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1997	longer exceeded.
		1998
		1999	In other words, this setting does not enforce a queue limit, but can be
		2000	used to make poll functions block if the limit is exceeded.
1388		2001
1389	This is a very bad function to use in interactive programs because it	2002	This is a very bad function to use in interactive programs because it
1390	blocks, and a bad way to reduce concurrency because it is inexact: Better	2003	blocks, and a bad way to reduce concurrency because it is inexact: Better
1391	use an C<aio_group> together with a feed callback.	2004	use an C<aio_group> together with a feed callback.
1392		2005
1393	Sets the maximum number of outstanding requests to C<$nreqs>. If you	2006	Its main use is in scripts without an event loop - when you want to stat
1394	do queue up more than this number of requests, the next call to the	2007	a lot of files, you can write somehting like this:
1395	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1396	function will block until the limit is no longer exceeded.
1397		2008
1398	The default value is very large, so there is no practical limit on the	2009	IO::AIO::max_outstanding 32;
1399	number of outstanding requests.
1400		2010
1401	You can still queue as many requests as you want. Therefore,	2011	for my $path (...) {
1402	C<max_outstanding> is mainly useful in simple scripts (with low values) or	2012	aio_stat $path , ...;
1403	as a stop gap to shield against fatal memory overflow (with large values).	2013	IO::AIO::poll_cb;
		2014	}
		2015
		2016	IO::AIO::flush;
		2017
		2018	The call to C<poll_cb> inside the loop will normally return instantly, but
		2019	as soon as more thna C<32> reqeusts are in-flight, it will block until
		2020	some requests have been handled. This keeps the loop from pushing a large
		2021	number of C<aio_stat> requests onto the queue.
		2022
		2023	The default value for C<max_outstanding> is very large, so there is no
		2024	practical limit on the number of outstanding requests.
1404		2025
1405	=back	2026	=back
1406		2027
1407	=head3 STATISTICAL INFORMATION	2028	=head3 STATISTICAL INFORMATION
1408		2029
…		…
1430		2051
1431	=back	2052	=back
1432		2053
1433	=head3 MISCELLANEOUS FUNCTIONS	2054	=head3 MISCELLANEOUS FUNCTIONS
1434		2055
1435	IO::AIO implements some functions that might be useful, but are not	2056	IO::AIO implements some functions that are useful when you want to use
1436	asynchronous.	2057	some "Advanced I/O" function not available to in Perl, without going the
		2058	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2059	counterpart.
1437		2060
1438	=over 4	2061	=over 4
1439		2062
1440	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count	2063	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
1441		2064
…		…
1446		2069
1447	Returns the number of bytes copied, or C<-1> on error.	2070	Returns the number of bytes copied, or C<-1> on error.
1448		2071
1449	=item IO::AIO::fadvise $fh, $offset, $len, $advice	2072	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1450		2073
1451	Simply calls the C<posix_fadvise> function (see it's	2074	Simply calls the C<posix_fadvise> function (see its
1452	manpage for details). The following advice constants are	2075	manpage for details). The following advice constants are
1453	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	2076	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1454	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	2077	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1455	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2078	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1456		2079
1457	On systems that do not implement C<posix_fadvise>, this function returns	2080	On systems that do not implement C<posix_fadvise>, this function returns
1458	ENOSYS, otherwise the return value of C<posix_fadvise>.	2081	ENOSYS, otherwise the return value of C<posix_fadvise>.
1459		2082
		2083	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		2084
		2085	Simply calls the C<posix_madvise> function (see its
		2086	manpage for details). The following advice constants are
		2087	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		2088	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>,
		2089	C<IO::AIO::MADV_FREE>.
		2090
		2091	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2092	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2093	will be reduced to fit into the C<$scalar>.
		2094
		2095	On systems that do not implement C<posix_madvise>, this function returns
		2096	ENOSYS, otherwise the return value of C<posix_madvise>.
		2097
		2098	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		2099
		2100	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		2101	$scalar (see its manpage for details). The following protect
		2102	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		2103	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2104
		2105	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2106	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2107	will be reduced to fit into the C<$scalar>.
		2108
		2109	On systems that do not implement C<mprotect>, this function returns
		2110	ENOSYS, otherwise the return value of C<mprotect>.
		2111
		2112	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		2113
		2114	Memory-maps a file (or anonymous memory range) and attaches it to the
		2115	given C<$scalar>, which will act like a string scalar. Returns true on
		2116	success, and false otherwise.
		2117
		2118	The scalar must exist, but its contents do not matter - this means you
		2119	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2120	the scalar first.
		2121
		2122	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
		2123	which don't change the string length, and most read-only operations such
		2124	as copying it or searching it with regexes and so on.
		2125
		2126	Anything else is unsafe and will, at best, result in memory leaks.
		2127
		2128	The memory map associated with the C<$scalar> is automatically removed
		2129	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
		2130	or C<IO::AIO::munmap> functions are called on it.
		2131
		2132	This calls the C<mmap>(2) function internally. See your system's manual
		2133	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		2134
		2135	The C<$length> must be larger than zero and smaller than the actual
		2136	filesize.
		2137
		2138	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		2139	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		2140
		2141	C<$flags> can be a combination of
		2142	C<IO::AIO::MAP_SHARED> or
		2143	C<IO::AIO::MAP_PRIVATE>,
		2144	or a number of system-specific flags (when not available, the are C<0>):
		2145	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
		2146	C<IO::AIO::MAP_LOCKED>,
		2147	C<IO::AIO::MAP_NORESERVE>,
		2148	C<IO::AIO::MAP_POPULATE>,
		2149	C<IO::AIO::MAP_NONBLOCK>,
		2150	C<IO::AIO::MAP_FIXED>,
		2151	C<IO::AIO::MAP_GROWSDOWN>,
		2152	C<IO::AIO::MAP_32BIT>,
		2153	C<IO::AIO::MAP_HUGETLB> or
		2154	C<IO::AIO::MAP_STACK>.
		2155
		2156	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		2157
		2158	C<$offset> is the offset from the start of the file - it generally must be
		2159	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		2160
		2161	Example:
		2162
		2163	use Digest::MD5;
		2164	use IO::AIO;
		2165
		2166	open my $fh, "<verybigfile"
		2167	or die "$!";
		2168
		2169	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		2170	or die "verybigfile: $!";
		2171
		2172	my $fast_md5 = md5 $data;
		2173
		2174	=item IO::AIO::munmap $scalar
		2175
		2176	Removes a previous mmap and undefines the C<$scalar>.
		2177
		2178	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		2179
		2180	Calls the C<munlock> function, undoing the effects of a previous
		2181	C<aio_mlock> call (see its description for details).
		2182
		2183	=item IO::AIO::munlockall
		2184
		2185	Calls the C<munlockall> function.
		2186
		2187	On systems that do not implement C<munlockall>, this function returns
		2188	ENOSYS, otherwise the return value of C<munlockall>.
		2189
		2190	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2191
		2192	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2193	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2194	should be the file offset.
		2195
		2196	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2197	silently corrupt the data in this case.
		2198
		2199	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2200	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2201	C<IO::AIO::SPLICE_F_GIFT>.
		2202
		2203	See the C<splice(2)> manpage for details.
		2204
		2205	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2206
		2207	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2208	description for C<IO::AIO::splice> above for details.
		2209
		2210	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2211
		2212	Attempts to query or change the pipe buffer size. Obviously works only
		2213	on pipes, and currently works only on GNU/Linux systems, and fails with
		2214	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2215	size on other systems, drop me a note.
		2216
		2217	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2218
		2219	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2220	C<$flags> is missing or C<0>, then this should be the same as a call to
		2221	perl's built-in C<pipe> function and create a new pipe, and works on
		2222	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2223	(..., 4096, O_BINARY)>.
		2224
		2225	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2226	the given flags (Linux 2.6.27, glibc 2.9).
		2227
		2228	On success, the read and write file handles are returned.
		2229
		2230	On error, nothing will be returned. If the pipe2 syscall is missing and
		2231	C<$flags> is non-zero, fails with C<ENOSYS>.
		2232
		2233	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2234	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2235	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2236
1460	=back	2237	=back
1461		2238
1462	=cut	2239	=cut
1463		2240
1464	min_parallel 8;	2241	min_parallel 8;
1465		2242
1466	END { flush }	2243	END { flush }
1467		2244
1468	1;	2245	1;
1469		2246
		2247	=head1 EVENT LOOP INTEGRATION
		2248
		2249	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		2250	automatically into many event loops:
		2251
		2252	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		2253	use AnyEvent::AIO;
		2254
		2255	You can also integrate IO::AIO manually into many event loops, here are
		2256	some examples of how to do this:
		2257
		2258	# EV integration
		2259	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		2260
		2261	# Event integration
		2262	Event->io (fd => IO::AIO::poll_fileno,
		2263	poll => 'r',
		2264	cb => \&IO::AIO::poll_cb);
		2265
		2266	# Glib/Gtk2 integration
		2267	add_watch Glib::IO IO::AIO::poll_fileno,
		2268	in => sub { IO::AIO::poll_cb; 1 };
		2269
		2270	# Tk integration
		2271	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		2272	readable => \&IO::AIO::poll_cb);
		2273
		2274	# Danga::Socket integration
		2275	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		2276	\&IO::AIO::poll_cb);
		2277
1470	=head2 FORK BEHAVIOUR	2278	=head2 FORK BEHAVIOUR
1471		2279
1472	This module should do "the right thing" when the process using it forks:	2280	Usage of pthreads in a program changes the semantics of fork
		2281	considerably. Specifically, only async-safe functions can be called after
		2282	fork. Perl doesn't know about this, so in general, you cannot call fork
		2283	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2284	pthreads, so this applies, but many other extensions and (for inexplicable
		2285	reasons) perl itself often is linked against pthreads, so this limitation
		2286	applies to quite a lot of perls.
1473		2287
1474	Before the fork, IO::AIO enters a quiescent state where no requests	2288	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1475	can be added in other threads and no results will be processed. After	2289	only works in the process that loaded it. Forking is fully supported, but
1476	the fork the parent simply leaves the quiescent state and continues	2290	using IO::AIO in the child is not.
1477	request/result processing, while the child frees the request/result queue
1478	(so that the requests started before the fork will only be handled in the
1479	parent). Threads will be started on demand until the limit set in the
1480	parent process has been reached again.
1481		2291
1482	In short: the parent will, after a short pause, continue as if fork had	2292	You might get around by not I<using> IO::AIO before (or after)
1483	not been called, while the child will act as if IO::AIO has not been used	2293	forking. You could also try to call the L<IO::AIO::reinit> function in the
1484	yet.	2294	child:
		2295
		2296	=over 4
		2297
		2298	=item IO::AIO::reinit
		2299
		2300	Abandons all current requests and I/O threads and simply reinitialises all
		2301	data structures. This is not an operation supported by any standards, but
		2302	happens to work on GNU/Linux and some newer BSD systems.
		2303
		2304	The only reasonable use for this function is to call it after forking, if
		2305	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2306	the process will result in undefined behaviour. Calling it at any time
		2307	will also result in any undefined (by POSIX) behaviour.
		2308
		2309	=back
1485		2310
1486	=head2 MEMORY USAGE	2311	=head2 MEMORY USAGE
1487		2312
1488	Per-request usage:	2313	Per-request usage:
1489		2314

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