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Revision 1.156 by root, Tue Jun 16 23:41:59 2009 UTC vs.
Revision 1.256 by root, Thu Jun 25 15:47:01 2015 UTC

…		…
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>
…		…
91	=head2 EXAMPLE	68	=head2 EXAMPLE
92		69
93	This is a simple example that uses the EV module and loads	70	This is a simple example that uses the EV module and loads
94	F</etc/passwd> asynchronously:	71	F</etc/passwd> asynchronously:
95		72
96	use Fcntl;
97	use EV;	73	use EV;
98	use IO::AIO;	74	use IO::AIO;
99		75
100	# register the IO::AIO callback with EV	76	# register the IO::AIO callback with EV
101	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	77	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
102		78
103	# queue the request to open /etc/passwd	79	# queue the request to open /etc/passwd
104	aio_open "/etc/passwd", O_RDONLY, 0, sub {	80	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
105	my $fh = shift	81	my $fh = shift
106	or die "error while opening: $!";	82	or die "error while opening: $!";
107		83
108	# stat'ing filehandles is generally non-blocking	84	# stat'ing filehandles is generally non-blocking
109	my $size = -s $fh;	85	my $size = -s $fh;
…		…
186		162
187	package IO::AIO;	163	package IO::AIO;
188		164
189	use Carp ();	165	use Carp ();
190		166
191	no warnings;	167	use common::sense;
192	use strict 'vars';
193		168
194	use base 'Exporter';	169	use base 'Exporter';
195		170
196	BEGIN {	171	BEGIN {
197	our $VERSION = '3.23';	172	our $VERSION = 4.32;
198		173
199	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	174	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
200	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx	175	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
201	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	176	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
202	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead	177	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_allocate
		178	aio_pathsync aio_readahead aio_fiemap
203	aio_rename aio_link aio_move aio_copy aio_group	179	aio_rename aio_link aio_move aio_copy aio_group
204	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	180	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
205	aio_chmod aio_utime aio_truncate);	181	aio_chmod aio_utime aio_truncate
		182	aio_msync aio_mtouch aio_mlock aio_mlockall
		183	aio_statvfs
		184	aio_wd);
206		185
207	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	186	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
208	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	187	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
209	min_parallel max_parallel max_idle	188	min_parallel max_parallel max_idle idle_timeout
210	nreqs nready npending nthreads	189	nreqs nready npending nthreads
211	max_poll_time max_poll_reqs);	190	max_poll_time max_poll_reqs
		191	sendfile fadvise madvise
		192	mmap munmap munlock munlockall);
212		193
213	push @AIO_REQ, qw(aio_busy); # not exported	194	push @AIO_REQ, qw(aio_busy); # not exported
214		195
215	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	196	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
216		197
…		…
218	XSLoader::load ("IO::AIO", $VERSION);	199	XSLoader::load ("IO::AIO", $VERSION);
219	}	200	}
220		201
221	=head1 FUNCTIONS	202	=head1 FUNCTIONS
222		203
223	=head2 AIO REQUEST FUNCTIONS	204	=head2 QUICK OVERVIEW
		205
		206	This section simply lists the prototypes most of the functions for
		207	quick reference. See the following sections for function-by-function
		208	documentation.
		209
		210	aio_wd $pathname, $callback->($wd)
		211	aio_open $pathname, $flags, $mode, $callback->($fh)
		212	aio_close $fh, $callback->($status)
		213	aio_seek $fh,$offset,$whence, $callback->($offs)
		214	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		215	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		216	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		217	aio_readahead $fh,$offset,$length, $callback->($retval)
		218	aio_stat $fh_or_path, $callback->($status)
		219	aio_lstat $fh, $callback->($status)
		220	aio_statvfs $fh_or_path, $callback->($statvfs)
		221	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		222	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		223	aio_chmod $fh_or_path, $mode, $callback->($status)
		224	aio_truncate $fh_or_path, $offset, $callback->($status)
		225	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		226	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		227	aio_unlink $pathname, $callback->($status)
		228	aio_mknod $pathname, $mode, $dev, $callback->($status)
		229	aio_link $srcpath, $dstpath, $callback->($status)
		230	aio_symlink $srcpath, $dstpath, $callback->($status)
		231	aio_readlink $pathname, $callback->($link)
		232	aio_realpath $pathname, $callback->($path)
		233	aio_rename $srcpath, $dstpath, $callback->($status)
		234	aio_mkdir $pathname, $mode, $callback->($status)
		235	aio_rmdir $pathname, $callback->($status)
		236	aio_readdir $pathname, $callback->($entries)
		237	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		238	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		239	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		240	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		241	aio_load $pathname, $data, $callback->($status)
		242	aio_copy $srcpath, $dstpath, $callback->($status)
		243	aio_move $srcpath, $dstpath, $callback->($status)
		244	aio_rmtree $pathname, $callback->($status)
		245	aio_sync $callback->($status)
		246	aio_syncfs $fh, $callback->($status)
		247	aio_fsync $fh, $callback->($status)
		248	aio_fdatasync $fh, $callback->($status)
		249	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		250	aio_pathsync $pathname, $callback->($status)
		251	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		252	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		253	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		254	aio_mlockall $flags, $callback->($status)
		255	aio_group $callback->(...)
		256	aio_nop $callback->()
		257
		258	$prev_pri = aioreq_pri [$pri]
		259	aioreq_nice $pri_adjust
		260
		261	IO::AIO::poll_wait
		262	IO::AIO::poll_cb
		263	IO::AIO::poll
		264	IO::AIO::flush
		265	IO::AIO::max_poll_reqs $nreqs
		266	IO::AIO::max_poll_time $seconds
		267	IO::AIO::min_parallel $nthreads
		268	IO::AIO::max_parallel $nthreads
		269	IO::AIO::max_idle $nthreads
		270	IO::AIO::idle_timeout $seconds
		271	IO::AIO::max_outstanding $maxreqs
		272	IO::AIO::nreqs
		273	IO::AIO::nready
		274	IO::AIO::npending
		275
		276	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		277	IO::AIO::fadvise $fh, $offset, $len, $advice
		278	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		279	IO::AIO::munmap $scalar
		280	IO::AIO::madvise $scalar, $offset, $length, $advice
		281	IO::AIO::mprotect $scalar, $offset, $length, $protect
		282	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		283	IO::AIO::munlockall
		284
		285	=head2 API NOTES
224		286
225	All the C<aio_*> calls are more or less thin wrappers around the syscall	287	All the C<aio_*> calls are more or less thin wrappers around the syscall
226	with the same name (sans C<aio_>). The arguments are similar or identical,	288	with the same name (sans C<aio_>). The arguments are similar or identical,
227	and they all accept an additional (and optional) C<$callback> argument	289	and they all accept an additional (and optional) C<$callback> argument
228	which must be a code reference. This code reference will get called with	290	which must be a code reference. This code reference will be called after
229	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	291	the syscall has been executed in an asynchronous fashion. The results
230	perl, which usually delivers "false") as its sole argument after the given	292	of the request will be passed as arguments to the callback (and, if an
231	syscall has been executed asynchronously.	293	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		294	most syscalls return C<-1> on error, unlike perl, which usually delivers
		295	"false").
		296
		297	Some requests (such as C<aio_readdir>) pass the actual results and
		298	communicate failures by passing C<undef>.
232		299
233	All functions expecting a filehandle keep a copy of the filehandle	300	All functions expecting a filehandle keep a copy of the filehandle
234	internally until the request has finished.	301	internally until the request has finished.
235		302
236	All functions return request objects of type L<IO::AIO::REQ> that allow	303	All functions return request objects of type L<IO::AIO::REQ> that allow
237	further manipulation of those requests while they are in-flight.	304	further manipulation of those requests while they are in-flight.
238		305
239	The pathnames you pass to these routines I<must> be absolute and	306	The pathnames you pass to these routines I<should> be absolute. The
240	encoded as octets. The reason for the former is that at the time the	307	reason for this is that at the time the request is being executed, the
241	request is being executed, the current working directory could have	308	current working directory could have changed. Alternatively, you can
242	changed. Alternatively, you can make sure that you never change the	309	make sure that you never change the current working directory anywhere
243	current working directory anywhere in the program and then use relative	310	in the program and then use relative paths. You can also take advantage
244	paths.	311	of IO::AIOs working directory abstraction, that lets you specify paths
		312	relative to some previously-opened "working directory object" - see the
		313	description of the C<IO::AIO::WD> class later in this document.
245		314
246	To encode pathnames as octets, either make sure you either: a) always pass	315	To encode pathnames as octets, either make sure you either: a) always pass
247	in filenames you got from outside (command line, readdir etc.) without	316	in filenames you got from outside (command line, readdir etc.) without
248	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	317	tinkering, b) are in your native filesystem encoding, c) use the Encode
249	your pathnames to the locale (or other) encoding in effect in the user	318	module and encode your pathnames to the locale (or other) encoding in
250	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	319	effect in the user environment, d) use Glib::filename_from_unicode on
251	use something else to ensure your scalar has the correct contents.	320	unicode filenames or e) use something else to ensure your scalar has the
		321	correct contents.
252		322
253	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	323	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
254	handles correctly whether it is set or not.	324	handles correctly whether it is set or not.
		325
		326	=head2 AIO REQUEST FUNCTIONS
255		327
256	=over 4	328	=over 4
257		329
258	=item $prev_pri = aioreq_pri [$pri]	330	=item $prev_pri = aioreq_pri [$pri]
259		331
…		…
289		361
290		362
291	=item aio_open $pathname, $flags, $mode, $callback->($fh)	363	=item aio_open $pathname, $flags, $mode, $callback->($fh)
292		364
293	Asynchronously open or create a file and call the callback with a newly	365	Asynchronously open or create a file and call the callback with a newly
294	created filehandle for the file.	366	created filehandle for the file (or C<undef> in case of an error).
295		367
296	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	368	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
297	for an explanation.	369	for an explanation.
298		370
299	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	371	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
306	by the umask in effect then the request is being executed, so better never	378	by the umask in effect then the request is being executed, so better never
307	change the umask.	379	change the umask.
308		380
309	Example:	381	Example:
310		382
311	aio_open "/etc/passwd", O_RDONLY, 0, sub {	383	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
312	if ($_[0]) {	384	if ($_[0]) {
313	print "open successful, fh is $_[0]\n";	385	print "open successful, fh is $_[0]\n";
314	...	386	...
315	} else {	387	} else {
316	die "open failed: $!\n";	388	die "open failed: $!\n";
317	}	389	}
318	};	390	};
319		391
		392	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		393	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		394	following POSIX and non-POSIX constants are available (missing ones on
		395	your system are, as usual, C<0>):
		396
		397	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		398	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		399	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
		400
320		401
321	=item aio_close $fh, $callback->($status)	402	=item aio_close $fh, $callback->($status)
322		403
323	Asynchronously close a file and call the callback with the result	404	Asynchronously close a file and call the callback with the result
324	code.	405	code.
…		…
332		413
333	Or in other words: the file descriptor will be closed, but it will not be	414	Or in other words: the file descriptor will be closed, but it will not be
334	free for reuse until the perl filehandle is closed.	415	free for reuse until the perl filehandle is closed.
335		416
336	=cut	417	=cut
		418
		419	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		420
		421	Seeks the filehandle to the new C<$offset>, similarly to perl's
		422	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		423	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		424	C<IO::AIO::SEEK_END>).
		425
		426	The resulting absolute offset will be passed to the callback, or C<-1> in
		427	case of an error.
		428
		429	In theory, the C<$whence> constants could be different than the
		430	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		431	so don't panic.
		432
		433	As a GNU/Linux (and maybe Solaris) extension, also the constants
		434	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		435	could be found. No guarantees about suitability for use in C<aio_seek> or
		436	Perl's C<sysseek> can be made though, although I would naively assume they
		437	"just work".
337		438
338	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	439	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
339		440
340	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	441	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
341		442
…		…
374		475
375	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	476	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
376	reading at byte offset C<$in_offset>, and starts writing at the current	477	reading at byte offset C<$in_offset>, and starts writing at the current
377	file offset of C<$out_fh>. Because of that, it is not safe to issue more	478	file offset of C<$out_fh>. Because of that, it is not safe to issue more
378	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	479	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
379	other.	480	other. The same C<$in_fh> works fine though, as this function does not
		481	move or use the file offset of C<$in_fh>.
380		482
		483	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		484	are written, and there is no way to find out how many more bytes have been
		485	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		486	number of bytes written to C<$out_fh>. Only if the result value equals
		487	C<$length> one can assume that C<$length> bytes have been read.
		488
		489	Unlike with other C<aio_> functions, it makes a lot of sense to use
		490	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		491	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		492	the socket I/O will be non-blocking. Note, however, that you can run
		493	into a trap where C<aio_sendfile> reads some data with readahead, then
		494	fails to write all data, and when the socket is ready the next time, the
		495	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		496	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		497	resource usage.
		498
381	This call tries to make use of a native C<sendfile> syscall to provide	499	This call tries to make use of a native C<sendfile>-like syscall to
382	zero-copy operation. For this to work, C<$out_fh> should refer to a	500	provide zero-copy operation. For this to work, C<$out_fh> should refer to
383	socket, and C<$in_fh> should refer to mmap'able file.	501	a socket, and C<$in_fh> should refer to an mmap'able file.
384		502
385	If the native sendfile call fails or is not implemented, it will be	503	If a native sendfile cannot be found or it fails with C<ENOSYS>,
386	emulated, so you can call C<aio_sendfile> on any type of filehandle	504	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		505	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
387	regardless of the limitations of the operating system.	506	type of filehandle regardless of the limitations of the operating system.
388		507
389	Please note, however, that C<aio_sendfile> can read more bytes from	508	As native sendfile syscalls (as practically any non-POSIX interface hacked
390	C<$in_fh> than are written, and there is no way to find out how many	509	together in a hurry to improve benchmark numbers) tend to be rather buggy
391	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	510	on many systems, this implementation tries to work around some known bugs
392	provides the number of bytes written to C<$out_fh>. Only if the result	511	in Linux and FreeBSD kernels (probably others, too), but that might fail,
393	value equals C<$length> one can assume that C<$length> bytes have been	512	so you really really should check the return value of C<aio_sendfile> -
394	read.	513	fewre bytes than expected might have been transferred.
395		514
396		515
397	=item aio_readahead $fh,$offset,$length, $callback->($retval)	516	=item aio_readahead $fh,$offset,$length, $callback->($retval)
398		517
399	C<aio_readahead> populates the page cache with data from a file so that	518	C<aio_readahead> populates the page cache with data from a file so that
…		…
422		541
423	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	542	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
424	error when stat'ing a large file, the results will be silently truncated	543	error when stat'ing a large file, the results will be silently truncated
425	unless perl itself is compiled with large file support.	544	unless perl itself is compiled with large file support.
426		545
		546	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		547	following constants and functions (if not implemented, the constants will
		548	be C<0> and the functions will either C<croak> or fall back on traditional
		549	behaviour).
		550
		551	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		552	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		553	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		554
427	Example: Print the length of F</etc/passwd>:	555	Example: Print the length of F</etc/passwd>:
428		556
429	aio_stat "/etc/passwd", sub {	557	aio_stat "/etc/passwd", sub {
430	$_[0] and die "stat failed: $!";	558	$_[0] and die "stat failed: $!";
431	print "size is ", -s _, "\n";	559	print "size is ", -s _, "\n";
432	};	560	};
433		561
434		562
		563	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		564
		565	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		566	whether a file handle or path was passed.
		567
		568	On success, the callback is passed a hash reference with the following
		569	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		570	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		571	is passed.
		572
		573	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		574	C<ST_NOSUID>.
		575
		576	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		577	their correct value when available, or to C<0> on systems that do
		578	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		579	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		580	C<ST_NODIRATIME> and C<ST_RELATIME>.
		581
		582	Example: stat C</wd> and dump out the data if successful.
		583
		584	aio_statvfs "/wd", sub {
		585	my $f = $_[0]
		586	or die "statvfs: $!";
		587
		588	use Data::Dumper;
		589	say Dumper $f;
		590	};
		591
		592	# result:
		593	{
		594	bsize => 1024,
		595	bfree => 4333064312,
		596	blocks => 10253828096,
		597	files => 2050765568,
		598	flag => 4096,
		599	favail => 2042092649,
		600	bavail => 4333064312,
		601	ffree => 2042092649,
		602	namemax => 255,
		603	frsize => 1024,
		604	fsid => 1810
		605	}
		606
		607	Here is a (likely partial - send me updates!) list of fsid values used by
		608	Linux - it is safe to hardcode these when C<$^O> is C<linux>:
		609
		610	0x0000adf5 adfs
		611	0x0000adff affs
		612	0x5346414f afs
		613	0x09041934 anon-inode filesystem
		614	0x00000187 autofs
		615	0x42465331 befs
		616	0x1badface bfs
		617	0x42494e4d binfmt_misc
		618	0x9123683e btrfs
		619	0x0027e0eb cgroupfs
		620	0xff534d42 cifs
		621	0x73757245 coda
		622	0x012ff7b7 coh
		623	0x28cd3d45 cramfs
		624	0x453dcd28 cramfs-wend (wrong endianness)
		625	0x64626720 debugfs
		626	0x00001373 devfs
		627	0x00001cd1 devpts
		628	0x0000f15f ecryptfs
		629	0x00414a53 efs
		630	0x0000137d ext
		631	0x0000ef53 ext2/ext3
		632	0x0000ef51 ext2
		633	0x00004006 fat
		634	0x65735546 fuseblk
		635	0x65735543 fusectl
		636	0x0bad1dea futexfs
		637	0x01161970 gfs2
		638	0x47504653 gpfs
		639	0x00004244 hfs
		640	0xf995e849 hpfs
		641	0x958458f6 hugetlbfs
		642	0x2bad1dea inotifyfs
		643	0x00009660 isofs
		644	0x000072b6 jffs2
		645	0x3153464a jfs
		646	0x6b414653 k-afs
		647	0x0bd00bd0 lustre
		648	0x0000137f minix
		649	0x0000138f minix 30 char names
		650	0x00002468 minix v2
		651	0x00002478 minix v2 30 char names
		652	0x00004d5a minix v3
		653	0x19800202 mqueue
		654	0x00004d44 msdos
		655	0x0000564c novell
		656	0x00006969 nfs
		657	0x6e667364 nfsd
		658	0x00003434 nilfs
		659	0x5346544e ntfs
		660	0x00009fa1 openprom
		661	0x7461636F ocfs2
		662	0x00009fa0 proc
		663	0x6165676c pstorefs
		664	0x0000002f qnx4
		665	0x858458f6 ramfs
		666	0x52654973 reiserfs
		667	0x00007275 romfs
		668	0x67596969 rpc_pipefs
		669	0x73636673 securityfs
		670	0xf97cff8c selinux
		671	0x0000517b smb
		672	0x534f434b sockfs
		673	0x73717368 squashfs
		674	0x62656572 sysfs
		675	0x012ff7b6 sysv2
		676	0x012ff7b5 sysv4
		677	0x01021994 tmpfs
		678	0x15013346 udf
		679	0x00011954 ufs
		680	0x54190100 ufs byteswapped
		681	0x00009fa2 usbdevfs
		682	0x01021997 v9fs
		683	0xa501fcf5 vxfs
		684	0xabba1974 xenfs
		685	0x012ff7b4 xenix
		686	0x58465342 xfs
		687	0x012fd16d xia
		688
435	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	689	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
436		690
437	Works like perl's C<utime> function (including the special case of $atime	691	Works like perl's C<utime> function (including the special case of $atime
438	and $mtime being undef). Fractional times are supported if the underlying	692	and $mtime being undef). Fractional times are supported if the underlying
439	syscalls support them.	693	syscalls support them.
…		…
466	=item aio_truncate $fh_or_path, $offset, $callback->($status)	720	=item aio_truncate $fh_or_path, $offset, $callback->($status)
467		721
468	Works like truncate(2) or ftruncate(2).	722	Works like truncate(2) or ftruncate(2).
469		723
470		724
		725	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		726
		727	Allocates or frees disk space according to the C<$mode> argument. See the
		728	linux C<fallocate> documentation for details.
		729
		730	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		731	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		732	to deallocate a file range.
		733
		734	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		735	(without leaving a hole) and C<FALLOC_FL_ZERO_RANGE>, to zero a range (see
		736	your L<fallocate(2)> manpage).
		737
		738	The file system block size used by C<fallocate> is presumably the
		739	C<f_bsize> returned by C<statvfs>.
		740
		741	If C<fallocate> isn't available or cannot be emulated (currently no
		742	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		743
		744
471	=item aio_chmod $fh_or_path, $mode, $callback->($status)	745	=item aio_chmod $fh_or_path, $mode, $callback->($status)
472		746
473	Works like perl's C<chmod> function.	747	Works like perl's C<chmod> function.
474		748
475		749
…		…
477		751
478	Asynchronously unlink (delete) a file and call the callback with the	752	Asynchronously unlink (delete) a file and call the callback with the
479	result code.	753	result code.
480		754
481		755
482	=item aio_mknod $path, $mode, $dev, $callback->($status)	756	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
483		757
484	[EXPERIMENTAL]	758	[EXPERIMENTAL]
485		759
486	Asynchronously create a device node (or fifo). See mknod(2).	760	Asynchronously create a device node (or fifo). See mknod(2).
487		761
488	The only (POSIX-) portable way of calling this function is:	762	The only (POSIX-) portable way of calling this function is:
489		763
490	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	764	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
491		765
		766	See C<aio_stat> for info about some potentially helpful extra constants
		767	and functions.
492		768
493	=item aio_link $srcpath, $dstpath, $callback->($status)	769	=item aio_link $srcpath, $dstpath, $callback->($status)
494		770
495	Asynchronously create a new link to the existing object at C<$srcpath> at	771	Asynchronously create a new link to the existing object at C<$srcpath> at
496	the path C<$dstpath> and call the callback with the result code.	772	the path C<$dstpath> and call the callback with the result code.
…		…
500		776
501	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	777	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
502	the path C<$dstpath> and call the callback with the result code.	778	the path C<$dstpath> and call the callback with the result code.
503		779
504		780
505	=item aio_readlink $path, $callback->($link)	781	=item aio_readlink $pathname, $callback->($link)
506		782
507	Asynchronously read the symlink specified by C<$path> and pass it to	783	Asynchronously read the symlink specified by C<$path> and pass it to
508	the callback. If an error occurs, nothing or undef gets passed to the	784	the callback. If an error occurs, nothing or undef gets passed to the
509	callback.	785	callback.
510		786
511		787
		788	=item aio_realpath $pathname, $callback->($path)
		789
		790	Asynchronously make the path absolute and resolve any symlinks in
		791	C<$path>. The resulting path only consists of directories (same as
		792	L<Cwd::realpath>).
		793
		794	This request can be used to get the absolute path of the current working
		795	directory by passing it a path of F<.> (a single dot).
		796
		797
512	=item aio_rename $srcpath, $dstpath, $callback->($status)	798	=item aio_rename $srcpath, $dstpath, $callback->($status)
513		799
514	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	800	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
515	rename(2) and call the callback with the result code.	801	rename(2) and call the callback with the result code.
		802
		803	On systems that support the AIO::WD working directory abstraction
		804	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		805	of failing, C<rename> is called on the absolute path of C<$wd>.
516		806
517		807
518	=item aio_mkdir $pathname, $mode, $callback->($status)	808	=item aio_mkdir $pathname, $mode, $callback->($status)
519		809
520	Asynchronously mkdir (create) a directory and call the callback with	810	Asynchronously mkdir (create) a directory and call the callback with
…		…
525	=item aio_rmdir $pathname, $callback->($status)	815	=item aio_rmdir $pathname, $callback->($status)
526		816
527	Asynchronously rmdir (delete) a directory and call the callback with the	817	Asynchronously rmdir (delete) a directory and call the callback with the
528	result code.	818	result code.
529		819
		820	On systems that support the AIO::WD working directory abstraction
		821	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		822	C<rmdir> is called on the absolute path of C<$wd>.
		823
530		824
531	=item aio_readdir $pathname, $callback->($entries)	825	=item aio_readdir $pathname, $callback->($entries)
532		826
533	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	827	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
534	directory (i.e. opendir + readdir + closedir). The entries will not be	828	directory (i.e. opendir + readdir + closedir). The entries will not be
…		…
538	array-ref with the filenames.	832	array-ref with the filenames.
539		833
540		834
541	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	835	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
542		836
543	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	837	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
544	behaviour and output format. In case of an error, C<$entries> will be	838	tune behaviour and output format. In case of an error, C<$entries> will be
545	C<undef>.	839	C<undef>.
546		840
547	The flags are a combination of the following constants, ORed together (the	841	The flags are a combination of the following constants, ORed together (the
548	flags will also be passed to the callback, possibly modified):	842	flags will also be passed to the callback, possibly modified):
549		843
550	=over 4	844	=over 4
551		845
552	=item IO::AIO::READDIR_DENTS	846	=item IO::AIO::READDIR_DENTS
553		847
554	When this flag is off, then the callback gets an arrayref with of names	848	When this flag is off, then the callback gets an arrayref consisting of
555	only (as with C<aio_readdir>), otherwise it gets an arrayref with	849	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
556	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	850	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
557	entry in more detail.	851	entry in more detail.
558		852
559	C<$name> is the name of the entry.	853	C<$name> is the name of the entry.
560		854
…		…
573	systems that do not deliver the inode information.	867	systems that do not deliver the inode information.
574		868
575	=item IO::AIO::READDIR_DIRS_FIRST	869	=item IO::AIO::READDIR_DIRS_FIRST
576		870
577	When this flag is set, then the names will be returned in an order where	871	When this flag is set, then the names will be returned in an order where
578	likely directories come first. This is useful when you need to quickly	872	likely directories come first, in optimal stat order. This is useful when
579	find directories, or you want to find all directories while avoiding to	873	you need to quickly find directories, or you want to find all directories
580	stat() each entry.	874	while avoiding to stat() each entry.
581		875
582	If the system returns type information in readdir, then this is used	876	If the system returns type information in readdir, then this is used
583	to find directories directly. Otherwise, likely directories are files	877	to find directories directly. Otherwise, likely directories are names
584	beginning with ".", or otherwise files with no dots, of which files with	878	beginning with ".", or otherwise names with no dots, of which names with
585	short names are tried first.	879	short names are tried first.
586		880
587	=item IO::AIO::READDIR_STAT_ORDER	881	=item IO::AIO::READDIR_STAT_ORDER
588		882
589	When this flag is set, then the names will be returned in an order	883	When this flag is set, then the names will be returned in an order
…		…
596		890
597	=item IO::AIO::READDIR_FOUND_UNKNOWN	891	=item IO::AIO::READDIR_FOUND_UNKNOWN
598		892
599	This flag should not be set when calling C<aio_readdirx>. Instead, it	893	This flag should not be set when calling C<aio_readdirx>. Instead, it
600	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	894	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
601	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	895	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
602	C<$type>'s are known, which can be used to speed up some algorithms.	896	C<$type>'s are known, which can be used to speed up some algorithms.
603		897
604	=back	898	=back
605		899
606		900
607	=item aio_load $path, $data, $callback->($status)	901	=item aio_load $pathname, $data, $callback->($status)
608		902
609	This is a composite request that tries to fully load the given file into	903	This is a composite request that tries to fully load the given file into
610	memory. Status is the same as with aio_read.	904	memory. Status is the same as with aio_read.
611		905
612	=cut	906	=cut
…		…
634		928
635	=item aio_copy $srcpath, $dstpath, $callback->($status)	929	=item aio_copy $srcpath, $dstpath, $callback->($status)
636		930
637	Try to copy the I<file> (directories not supported as either source or	931	Try to copy the I<file> (directories not supported as either source or
638	destination) from C<$srcpath> to C<$dstpath> and call the callback with	932	destination) from C<$srcpath> to C<$dstpath> and call the callback with
639	the C<0> (error) or C<-1> ok.	933	a status of C<0> (ok) or C<-1> (error, see C<$!>).
640		934
641	This is a composite request that creates the destination file with	935	This is a composite request that creates the destination file with
642	mode 0200 and copies the contents of the source file into it using	936	mode 0200 and copies the contents of the source file into it using
643	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	937	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
644	uid/gid, in that order.	938	uid/gid, in that order.
…		…
656	my $grp = aio_group $cb;	950	my $grp = aio_group $cb;
657		951
658	aioreq_pri $pri;	952	aioreq_pri $pri;
659	add $grp aio_open $src, O_RDONLY, 0, sub {	953	add $grp aio_open $src, O_RDONLY, 0, sub {
660	if (my $src_fh = $_[0]) {	954	if (my $src_fh = $_[0]) {
661	my @stat = stat $src_fh; # hmm, might bock over nfs?	955	my @stat = stat $src_fh; # hmm, might block over nfs?
662		956
663	aioreq_pri $pri;	957	aioreq_pri $pri;
664	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	958	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
665	if (my $dst_fh = $_[0]) {	959	if (my $dst_fh = $_[0]) {
666	aioreq_pri $pri;	960	aioreq_pri $pri;
…		…
713		1007
714	=item aio_move $srcpath, $dstpath, $callback->($status)	1008	=item aio_move $srcpath, $dstpath, $callback->($status)
715		1009
716	Try to move the I<file> (directories not supported as either source or	1010	Try to move the I<file> (directories not supported as either source or
717	destination) from C<$srcpath> to C<$dstpath> and call the callback with	1011	destination) from C<$srcpath> to C<$dstpath> and call the callback with
718	the C<0> (error) or C<-1> ok.	1012	a status of C<0> (ok) or C<-1> (error, see C<$!>).
719		1013
720	This is a composite request that tries to rename(2) the file first; if	1014	This is a composite request that tries to rename(2) the file first; if
721	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if	1015	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
722	that is successful, unlinks the C<$srcpath>.	1016	that is successful, unlinks the C<$srcpath>.
723		1017
…		…
734	if ($_[0] && $! == EXDEV) {	1028	if ($_[0] && $! == EXDEV) {
735	aioreq_pri $pri;	1029	aioreq_pri $pri;
736	add $grp aio_copy $src, $dst, sub {	1030	add $grp aio_copy $src, $dst, sub {
737	$grp->result ($_[0]);	1031	$grp->result ($_[0]);
738		1032
739	if (!$_[0]) {	1033	unless ($_[0]) {
740	aioreq_pri $pri;	1034	aioreq_pri $pri;
741	add $grp aio_unlink $src;	1035	add $grp aio_unlink $src;
742	}	1036	}
743	};	1037	};
744	} else {	1038	} else {
…		…
747	};	1041	};
748		1042
749	$grp	1043	$grp
750	}	1044	}
751		1045
752	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1046	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
753		1047
754	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1048	Scans a directory (similar to C<aio_readdir>) but additionally tries to
755	efficiently separate the entries of directory C<$path> into two sets of	1049	efficiently separate the entries of directory C<$path> into two sets of
756	names, directories you can recurse into (directories), and ones you cannot	1050	names, directories you can recurse into (directories), and ones you cannot
757	recurse into (everything else, including symlinks to directories).	1051	recurse into (everything else, including symlinks to directories).
…		…
788	Then entries will be sorted into likely directories a non-initial dot	1082	Then entries will be sorted into likely directories a non-initial dot
789	currently) and likely non-directories (see C<aio_readdirx>). Then every	1083	currently) and likely non-directories (see C<aio_readdirx>). Then every
790	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	1084	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
791	in order of their inode numbers. If that succeeds, it assumes that the	1085	in order of their inode numbers. If that succeeds, it assumes that the
792	entry is a directory or a symlink to directory (which will be checked	1086	entry is a directory or a symlink to directory (which will be checked
793	seperately). This is often faster than stat'ing the entry itself because	1087	separately). This is often faster than stat'ing the entry itself because
794	filesystems might detect the type of the entry without reading the inode	1088	filesystems might detect the type of the entry without reading the inode
795	data (e.g. ext2fs filetype feature), even on systems that cannot return	1089	data (e.g. ext2fs filetype feature), even on systems that cannot return
796	the filetype information on readdir.	1090	the filetype information on readdir.
797		1091
798	If the known number of directories (link count - 2) has been reached, the	1092	If the known number of directories (link count - 2) has been reached, the
…		…
814		1108
815	my $grp = aio_group $cb;	1109	my $grp = aio_group $cb;
816		1110
817	$maxreq = 4 if $maxreq <= 0;	1111	$maxreq = 4 if $maxreq <= 0;
818		1112
819	# stat once	1113	# get a wd object
820	aioreq_pri $pri;	1114	aioreq_pri $pri;
821	add $grp aio_stat $path, sub {	1115	add $grp aio_wd $path, sub {
		1116	$_[0]
822	return $grp->result () if $_[0];	1117	or return $grp->result ();
823	my $now = time;
824	my $hash1 = join ":", (stat _)[0,1,3,7,9];
825		1118
826	# read the directory entries	1119	my $wd = [shift, "."];
		1120
		1121	# stat once
827	aioreq_pri $pri;	1122	aioreq_pri $pri;
828	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1123	add $grp aio_stat $wd, sub {
829	my $entries = shift
830	or return $grp->result ();	1124	return $grp->result () if $_[0];
		1125	my $now = time;
		1126	my $hash1 = join ":", (stat _)[0,1,3,7,9];
831		1127
832	# stat the dir another time	1128	# read the directory entries
833	aioreq_pri $pri;	1129	aioreq_pri $pri;
		1130	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1131	my $entries = shift
		1132	or return $grp->result ();
		1133
		1134	# stat the dir another time
		1135	aioreq_pri $pri;
834	add $grp aio_stat $path, sub {	1136	add $grp aio_stat $wd, sub {
835	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1137	my $hash2 = join ":", (stat _)[0,1,3,7,9];
836		1138
837	my $ndirs;	1139	my $ndirs;
838		1140
839	# take the slow route if anything looks fishy	1141	# take the slow route if anything looks fishy
840	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1142	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
841	$ndirs = -1;	1143	$ndirs = -1;
842	} else {	1144	} else {
843	# if nlink == 2, we are finished	1145	# if nlink == 2, we are finished
844	# for non-posix-fs's, we rely on nlink < 2	1146	# for non-posix-fs's, we rely on nlink < 2
845	$ndirs = (stat _)[3] - 2	1147	$ndirs = (stat _)[3] - 2
846	or return $grp->result ([], $entries);	1148	or return $grp->result ([], $entries);
847	}	1149	}
848		1150
849	my (@dirs, @nondirs);	1151	my (@dirs, @nondirs);
850		1152
851	my $statgrp = add $grp aio_group sub {	1153	my $statgrp = add $grp aio_group sub {
852	$grp->result (\@dirs, \@nondirs);	1154	$grp->result (\@dirs, \@nondirs);
853	};	1155	};
854		1156
855	limit $statgrp $maxreq;	1157	limit $statgrp $maxreq;
856	feed $statgrp sub {	1158	feed $statgrp sub {
857	return unless @$entries;	1159	return unless @$entries;
858	my $entry = shift @$entries;	1160	my $entry = shift @$entries;
859		1161
860	aioreq_pri $pri;	1162	aioreq_pri $pri;
		1163	$wd->[1] = "$entry/.";
861	add $statgrp aio_stat "$path/$entry/.", sub {	1164	add $statgrp aio_stat $wd, sub {
862	if ($_[0] < 0) {	1165	if ($_[0] < 0) {
863	push @nondirs, $entry;	1166	push @nondirs, $entry;
864	} else {	1167	} else {
865	# need to check for real directory	1168	# need to check for real directory
866	aioreq_pri $pri;	1169	aioreq_pri $pri;
		1170	$wd->[1] = $entry;
867	add $statgrp aio_lstat "$path/$entry", sub {	1171	add $statgrp aio_lstat $wd, sub {
868	if (-d _) {	1172	if (-d _) {
869	push @dirs, $entry;	1173	push @dirs, $entry;
870		1174
871	unless (--$ndirs) {	1175	unless (--$ndirs) {
872	push @nondirs, @$entries;	1176	push @nondirs, @$entries;
873	feed $statgrp;	1177	feed $statgrp;
		1178	}
		1179	} else {
		1180	push @nondirs, $entry;
874	}	1181	}
875	} else {
876	push @nondirs, $entry;
877	}	1182	}
878	}	1183	}
879	}	1184	};
880	};	1185	};
881	};	1186	};
882	};	1187	};
883	};	1188	};
884	};	1189	};
885		1190
886	$grp	1191	$grp
887	}	1192	}
888		1193
889	=item aio_rmtree $path, $callback->($status)	1194	=item aio_rmtree $pathname, $callback->($status)
890		1195
891	Delete a directory tree starting (and including) C<$path>, return the	1196	Delete a directory tree starting (and including) C<$path>, return the
892	status of the final C<rmdir> only. This is a composite request that	1197	status of the final C<rmdir> only. This is a composite request that
893	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1198	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
894	everything else.	1199	everything else.
895		1200
896	=cut	1201	=cut
897		1202
…		…
936	callback with the fdatasync result code.	1241	callback with the fdatasync result code.
937		1242
938	If this call isn't available because your OS lacks it or it couldn't be	1243	If this call isn't available because your OS lacks it or it couldn't be
939	detected, it will be emulated by calling C<fsync> instead.	1244	detected, it will be emulated by calling C<fsync> instead.
940		1245
		1246	=item aio_syncfs $fh, $callback->($status)
		1247
		1248	Asynchronously call the syncfs syscall to sync the filesystem associated
		1249	to the given filehandle and call the callback with the syncfs result
		1250	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1251	errno to C<ENOSYS> nevertheless.
		1252
941	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1253	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
942		1254
943	Sync the data portion of the file specified by C<$offset> and C<$length>	1255	Sync the data portion of the file specified by C<$offset> and C<$length>
944	to disk (but NOT the metadata), by calling the Linux-specific	1256	to disk (but NOT the metadata), by calling the Linux-specific
945	sync_file_range call. If sync_file_range is not available or it returns	1257	sync_file_range call. If sync_file_range is not available or it returns
…		…
948	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1260	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
949	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1261	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
950	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1262	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
951	manpage for details.	1263	manpage for details.
952		1264
953	=item aio_pathsync $path, $callback->($status)	1265	=item aio_pathsync $pathname, $callback->($status)
954		1266
955	This request tries to open, fsync and close the given path. This is a	1267	This request tries to open, fsync and close the given path. This is a
956	composite request intended to sync directories after directory operations	1268	composite request intended to sync directories after directory operations
957	(E.g. rename). This might not work on all operating systems or have any	1269	(E.g. rename). This might not work on all operating systems or have any
958	specific effect, but usually it makes sure that directory changes get	1270	specific effect, but usually it makes sure that directory changes get
959	written to disc. It works for anything that can be opened for read-only,	1271	written to disc. It works for anything that can be opened for read-only,
960	not just directories.	1272	not just directories.
		1273
		1274	Future versions of this function might fall back to other methods when
		1275	C<fsync> on the directory fails (such as calling C<sync>).
961		1276
962	Passes C<0> when everything went ok, and C<-1> on error.	1277	Passes C<0> when everything went ok, and C<-1> on error.
963		1278
964	=cut	1279	=cut
965		1280
…		…
986	};	1301	};
987		1302
988	$grp	1303	$grp
989	}	1304	}
990		1305
		1306	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1307
		1308	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1309	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1310	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1311	scalar must only be modified in-place while an aio operation is pending on
		1312	it).
		1313
		1314	It calls the C<msync> function of your OS, if available, with the memory
		1315	area starting at C<$offset> in the string and ending C<$length> bytes
		1316	later. If C<$length> is negative, counts from the end, and if C<$length>
		1317	is C<undef>, then it goes till the end of the string. The flags can be
		1318	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1319	C<IO::AIO::MS_SYNC>.
		1320
		1321	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1322
		1323	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1324	scalars.
		1325
		1326	It touches (reads or writes) all memory pages in the specified
		1327	range inside the scalar. All caveats and parameters are the same
		1328	as for C<aio_msync>, above, except for flags, which must be either
		1329	C<0> (which reads all pages and ensures they are instantiated) or
		1330	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
		1331	writing an octet from it, which dirties the page).
		1332
		1333	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1334
		1335	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1336	scalars.
		1337
		1338	It reads in all the pages of the underlying storage into memory (if any)
		1339	and locks them, so they are not getting swapped/paged out or removed.
		1340
		1341	If C<$length> is undefined, then the scalar will be locked till the end.
		1342
		1343	On systems that do not implement C<mlock>, this function returns C<-1>
		1344	and sets errno to C<ENOSYS>.
		1345
		1346	Note that the corresponding C<munlock> is synchronous and is
		1347	documented under L<MISCELLANEOUS FUNCTIONS>.
		1348
		1349	Example: open a file, mmap and mlock it - both will be undone when
		1350	C<$data> gets destroyed.
		1351
		1352	open my $fh, "<", $path or die "$path: $!";
		1353	my $data;
		1354	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1355	aio_mlock $data; # mlock in background
		1356
		1357	=item aio_mlockall $flags, $callback->($status)
		1358
		1359	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1360	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1361
		1362	On systems that do not implement C<mlockall>, this function returns C<-1>
		1363	and sets errno to C<ENOSYS>.
		1364
		1365	Note that the corresponding C<munlockall> is synchronous and is
		1366	documented under L<MISCELLANEOUS FUNCTIONS>.
		1367
		1368	Example: asynchronously lock all current and future pages into memory.
		1369
		1370	aio_mlockall IO::AIO::MCL_FUTURE;
		1371
		1372	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1373
		1374	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1375	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1376	the ioctl is not available on your OS, then this request will fail with
		1377	C<ENOSYS>.
		1378
		1379	C<$start> is the starting offset to query extents for, C<$length> is the
		1380	size of the range to query - if it is C<undef>, then the whole file will
		1381	be queried.
		1382
		1383	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1384	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1385	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1386	the data portion.
		1387
		1388	C<$count> is the maximum number of extent records to return. If it is
		1389	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1390	case, if it is C<0>, then the callback receives the number of extents
		1391	instead of the extents themselves (which is unreliable, see below).
		1392
		1393	If an error occurs, the callback receives no arguments. The special
		1394	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1395
		1396	Otherwise, the callback receives an array reference with extent
		1397	structures. Each extent structure is an array reference itself, with the
		1398	following members:
		1399
		1400	[$logical, $physical, $length, $flags]
		1401
		1402	Flags is any combination of the following flag values (typically either C<0>
		1403	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1404
		1405	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1406	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1407	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1408	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1409	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1410	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1411
		1412	At the time of this writing (Linux 3.2), this requets is unreliable unless
		1413	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1414	it to return all extents of a range for files with large number of
		1415	extents. The code works around all these issues if C<$count> is undef.
		1416
991	=item aio_group $callback->(...)	1417	=item aio_group $callback->(...)
992		1418
993	This is a very special aio request: Instead of doing something, it is a	1419	This is a very special aio request: Instead of doing something, it is a
994	container for other aio requests, which is useful if you want to bundle	1420	container for other aio requests, which is useful if you want to bundle
995	many requests into a single, composite, request with a definite callback	1421	many requests into a single, composite, request with a definite callback
…		…
1031	like sleep and file handle readable/writable, the overhead this creates is	1457	like sleep and file handle readable/writable, the overhead this creates is
1032	immense (it blocks a thread for a long time) so do not use this function	1458	immense (it blocks a thread for a long time) so do not use this function
1033	except to put your application under artificial I/O pressure.	1459	except to put your application under artificial I/O pressure.
1034		1460
1035	=back	1461	=back
		1462
		1463
		1464	=head2 IO::AIO::WD - multiple working directories
		1465
		1466	Your process only has one current working directory, which is used by all
		1467	threads. This makes it hard to use relative paths (some other component
		1468	could call C<chdir> at any time, and it is hard to control when the path
		1469	will be used by IO::AIO).
		1470
		1471	One solution for this is to always use absolute paths. This usually works,
		1472	but can be quite slow (the kernel has to walk the whole path on every
		1473	access), and can also be a hassle to implement.
		1474
		1475	Newer POSIX systems have a number of functions (openat, fdopendir,
		1476	futimensat and so on) that make it possible to specify working directories
		1477	per operation.
		1478
		1479	For portability, and because the clowns who "designed", or shall I write,
		1480	perpetrated this new interface were obviously half-drunk, this abstraction
		1481	cannot be perfect, though.
		1482
		1483	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1484	object. This object stores the canonicalised, absolute version of the
		1485	path, and on systems that allow it, also a directory file descriptor.
		1486
		1487	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1488	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1489	object and a pathname instead (or the IO::AIO::WD object alone, which
		1490	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1491	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1492	to that IO::AIO::WD object.
		1493
		1494	For example, to get a wd object for F</etc> and then stat F<passwd>
		1495	inside, you would write:
		1496
		1497	aio_wd "/etc", sub {
		1498	my $etcdir = shift;
		1499
		1500	# although $etcdir can be undef on error, there is generally no reason
		1501	# to check for errors here, as aio_stat will fail with ENOENT
		1502	# when $etcdir is undef.
		1503
		1504	aio_stat [$etcdir, "passwd"], sub {
		1505	# yay
		1506	};
		1507	};
		1508
		1509	The fact that C<aio_wd> is a request and not a normal function shows that
		1510	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1511	which is why it is done asynchronously.
		1512
		1513	To stat the directory obtained with C<aio_wd> above, one could write
		1514	either of the following three request calls:
		1515
		1516	aio_lstat "/etc" , sub { ... # pathname as normal string
		1517	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1518	aio_lstat $wd , sub { ... # shorthand for the previous
		1519
		1520	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1521	object and the pathname string, so you could write the following without
		1522	causing any issues due to C<$path> getting reused:
		1523
		1524	my $path = [$wd, undef];
		1525
		1526	for my $name (qw(abc def ghi)) {
		1527	$path->[1] = $name;
		1528	aio_stat $path, sub {
		1529	# ...
		1530	};
		1531	}
		1532
		1533	There are some caveats: when directories get renamed (or deleted), the
		1534	pathname string doesn't change, so will point to the new directory (or
		1535	nowhere at all), while the directory fd, if available on the system,
		1536	will still point to the original directory. Most functions accepting a
		1537	pathname will use the directory fd on newer systems, and the string on
		1538	older systems. Some functions (such as realpath) will always rely on the
		1539	string form of the pathname.
		1540
		1541	So this functionality is mainly useful to get some protection against
		1542	C<chdir>, to easily get an absolute path out of a relative path for future
		1543	reference, and to speed up doing many operations in the same directory
		1544	(e.g. when stat'ing all files in a directory).
		1545
		1546	The following functions implement this working directory abstraction:
		1547
		1548	=over 4
		1549
		1550	=item aio_wd $pathname, $callback->($wd)
		1551
		1552	Asynchonously canonicalise the given pathname and convert it to an
		1553	IO::AIO::WD object representing it. If possible and supported on the
		1554	system, also open a directory fd to speed up pathname resolution relative
		1555	to this working directory.
		1556
		1557	If something goes wrong, then C<undef> is passwd to the callback instead
		1558	of a working directory object and C<$!> is set appropriately. Since
		1559	passing C<undef> as working directory component of a pathname fails the
		1560	request with C<ENOENT>, there is often no need for error checking in the
		1561	C<aio_wd> callback, as future requests using the value will fail in the
		1562	expected way.
		1563
		1564	=item IO::AIO::CWD
		1565
		1566	This is a compiletime constant (object) that represents the process
		1567	current working directory.
		1568
		1569	Specifying this object as working directory object for a pathname is as if
		1570	the pathname would be specified directly, without a directory object. For
		1571	example, these calls are functionally identical:
		1572
		1573	aio_stat "somefile", sub { ... };
		1574	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1575
		1576	=back
		1577
		1578	To recover the path associated with an IO::AIO::WD object, you can use
		1579	C<aio_realpath>:
		1580
		1581	aio_realpath $wd, sub {
		1582	warn "path is $_[0]\n";
		1583	};
		1584
		1585	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1586	sometimes, fall back to using an absolue path.
1036		1587
1037	=head2 IO::AIO::REQ CLASS	1588	=head2 IO::AIO::REQ CLASS
1038		1589
1039	All non-aggregate C<aio_*> functions return an object of this class when	1590	All non-aggregate C<aio_*> functions return an object of this class when
1040	called in non-void context.	1591	called in non-void context.
…		…
1130	=item $grp->cancel_subs	1681	=item $grp->cancel_subs
1131		1682
1132	Cancel all subrequests and clears any feeder, but not the group request	1683	Cancel all subrequests and clears any feeder, but not the group request
1133	itself. Useful when you queued a lot of events but got a result early.	1684	itself. Useful when you queued a lot of events but got a result early.
1134		1685
		1686	The group request will finish normally (you cannot add requests to the
		1687	group).
		1688
1135	=item $grp->result (...)	1689	=item $grp->result (...)
1136		1690
1137	Set the result value(s) that will be passed to the group callback when all	1691	Set the result value(s) that will be passed to the group callback when all
1138	subrequests have finished and set the groups errno to the current value	1692	subrequests have finished and set the groups errno to the current value
1139	of errno (just like calling C<errno> without an error number). By default,	1693	of errno (just like calling C<errno> without an error number). By default,
…		…
1155		1709
1156	Sets a feeder/generator on this group: every group can have an attached	1710	Sets a feeder/generator on this group: every group can have an attached
1157	generator that generates requests if idle. The idea behind this is that,	1711	generator that generates requests if idle. The idea behind this is that,
1158	although you could just queue as many requests as you want in a group,	1712	although you could just queue as many requests as you want in a group,
1159	this might starve other requests for a potentially long time. For example,	1713	this might starve other requests for a potentially long time. For example,
1160	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1714	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1161	delaying any later requests for a long time.	1715	requests, delaying any later requests for a long time.
1162		1716
1163	To avoid this, and allow incremental generation of requests, you can	1717	To avoid this, and allow incremental generation of requests, you can
1164	instead a group and set a feeder on it that generates those requests. The	1718	instead a group and set a feeder on it that generates those requests. The
1165	feed callback will be called whenever there are few enough (see C<limit>,	1719	feed callback will be called whenever there are few enough (see C<limit>,
1166	below) requests active in the group itself and is expected to queue more	1720	below) requests active in the group itself and is expected to queue more
…		…
1215		1769
1216	See C<poll_cb> for an example.	1770	See C<poll_cb> for an example.
1217		1771
1218	=item IO::AIO::poll_cb	1772	=item IO::AIO::poll_cb
1219		1773
1220	Process some outstanding events on the result pipe. You have to call this	1774	Process some requests that have reached the result phase (i.e. they have
1221	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1775	been executed but the results are not yet reported). You have to call
1222	returned earlier for whatever reason. Returns immediately when no events	1776	this "regularly" to finish outstanding requests.
1223	are outstanding. The amount of events processed depends on the settings of
1224	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1225		1777
		1778	Returns C<0> if all events could be processed (or there were no
		1779	events to process), or C<-1> if it returned earlier for whatever
		1780	reason. Returns immediately when no events are outstanding. The amount
		1781	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
		1782	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
		1783
1226	If not all requests were processed for whatever reason, the filehandle	1784	If not all requests were processed for whatever reason, the poll file
1227	will still be ready when C<poll_cb> returns, so normally you don't have to	1785	descriptor will still be ready when C<poll_cb> returns, so normally you
1228	do anything special to have it called later.	1786	don't have to do anything special to have it called later.
		1787
		1788	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1789	ready, it can be beneficial to call this function from loops which submit
		1790	a lot of requests, to make sure the results get processed when they become
		1791	available and not just when the loop is finished and the event loop takes
		1792	over again. This function returns very fast when there are no outstanding
		1793	requests.
1229		1794
1230	Example: Install an Event watcher that automatically calls	1795	Example: Install an Event watcher that automatically calls
1231	IO::AIO::poll_cb with high priority (more examples can be found in the	1796	IO::AIO::poll_cb with high priority (more examples can be found in the
1232	SYNOPSIS section, at the top of this document):	1797	SYNOPSIS section, at the top of this document):
1233		1798
1234	Event->io (fd => IO::AIO::poll_fileno,	1799	Event->io (fd => IO::AIO::poll_fileno,
1235	poll => 'r', async => 1,	1800	poll => 'r', async => 1,
1236	cb => \&IO::AIO::poll_cb);	1801	cb => \&IO::AIO::poll_cb);
		1802
		1803	=item IO::AIO::poll_wait
		1804
		1805	Wait until either at least one request is in the result phase or no
		1806	requests are outstanding anymore.
		1807
		1808	This is useful if you want to synchronously wait for some requests to
		1809	become ready, without actually handling them.
		1810
		1811	See C<nreqs> for an example.
		1812
		1813	=item IO::AIO::poll
		1814
		1815	Waits until some requests have been handled.
		1816
		1817	Returns the number of requests processed, but is otherwise strictly
		1818	equivalent to:
		1819
		1820	IO::AIO::poll_wait, IO::AIO::poll_cb
		1821
		1822	=item IO::AIO::flush
		1823
		1824	Wait till all outstanding AIO requests have been handled.
		1825
		1826	Strictly equivalent to:
		1827
		1828	IO::AIO::poll_wait, IO::AIO::poll_cb
		1829	while IO::AIO::nreqs;
1237		1830
1238	=item IO::AIO::max_poll_reqs $nreqs	1831	=item IO::AIO::max_poll_reqs $nreqs
1239		1832
1240	=item IO::AIO::max_poll_time $seconds	1833	=item IO::AIO::max_poll_time $seconds
1241		1834
…		…
1266	# use a low priority so other tasks have priority	1859	# use a low priority so other tasks have priority
1267	Event->io (fd => IO::AIO::poll_fileno,	1860	Event->io (fd => IO::AIO::poll_fileno,
1268	poll => 'r', nice => 1,	1861	poll => 'r', nice => 1,
1269	cb => &IO::AIO::poll_cb);	1862	cb => &IO::AIO::poll_cb);
1270		1863
1271	=item IO::AIO::poll_wait
1272
1273	If there are any outstanding requests and none of them in the result
1274	phase, wait till the result filehandle becomes ready for reading (simply
1275	does a C<select> on the filehandle. This is useful if you want to
1276	synchronously wait for some requests to finish).
1277
1278	See C<nreqs> for an example.
1279
1280	=item IO::AIO::poll
1281
1282	Waits until some requests have been handled.
1283
1284	Returns the number of requests processed, but is otherwise strictly
1285	equivalent to:
1286
1287	IO::AIO::poll_wait, IO::AIO::poll_cb
1288
1289	=item IO::AIO::flush
1290
1291	Wait till all outstanding AIO requests have been handled.
1292
1293	Strictly equivalent to:
1294
1295	IO::AIO::poll_wait, IO::AIO::poll_cb
1296	while IO::AIO::nreqs;
1297
1298	=back	1864	=back
1299		1865
1300	=head3 CONTROLLING THE NUMBER OF THREADS	1866	=head3 CONTROLLING THE NUMBER OF THREADS
1301		1867
1302	=over	1868	=over
…		…
1335		1901
1336	Under normal circumstances you don't need to call this function.	1902	Under normal circumstances you don't need to call this function.
1337		1903
1338	=item IO::AIO::max_idle $nthreads	1904	=item IO::AIO::max_idle $nthreads
1339		1905
1340	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1906	Limit the number of threads (default: 4) that are allowed to idle
1341	threads that did not get a request to process within 10 seconds). That	1907	(i.e., threads that did not get a request to process within the idle
1342	means if a thread becomes idle while C<$nthreads> other threads are also	1908	timeout (default: 10 seconds). That means if a thread becomes idle while
1343	idle, it will free its resources and exit.	1909	C<$nthreads> other threads are also idle, it will free its resources and
		1910	exit.
1344		1911
1345	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1912	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1346	to allow for extremely high load situations, but want to free resources	1913	to allow for extremely high load situations, but want to free resources
1347	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1914	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1348		1915
1349	The default is probably ok in most situations, especially if thread	1916	The default is probably ok in most situations, especially if thread
1350	creation is fast. If thread creation is very slow on your system you might	1917	creation is fast. If thread creation is very slow on your system you might
1351	want to use larger values.	1918	want to use larger values.
1352		1919
		1920	=item IO::AIO::idle_timeout $seconds
		1921
		1922	Sets the minimum idle timeout (default 10) after which worker threads are
		1923	allowed to exit. SEe C<IO::AIO::max_idle>.
		1924
1353	=item IO::AIO::max_outstanding $maxreqs	1925	=item IO::AIO::max_outstanding $maxreqs
		1926
		1927	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1928	you do queue up more than this number of requests, the next call to
		1929	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1930	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1931	longer exceeded.
		1932
		1933	In other words, this setting does not enforce a queue limit, but can be
		1934	used to make poll functions block if the limit is exceeded.
1354		1935
1355	This is a very bad function to use in interactive programs because it	1936	This is a very bad function to use in interactive programs because it
1356	blocks, and a bad way to reduce concurrency because it is inexact: Better	1937	blocks, and a bad way to reduce concurrency because it is inexact: Better
1357	use an C<aio_group> together with a feed callback.	1938	use an C<aio_group> together with a feed callback.
1358		1939
1359	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1940	Its main use is in scripts without an event loop - when you want to stat
1360	do queue up more than this number of requests, the next call to the	1941	a lot of files, you can write somehting like this:
1361	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1362	function will block until the limit is no longer exceeded.
1363		1942
1364	The default value is very large, so there is no practical limit on the	1943	IO::AIO::max_outstanding 32;
1365	number of outstanding requests.
1366		1944
1367	You can still queue as many requests as you want. Therefore,	1945	for my $path (...) {
1368	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1946	aio_stat $path , ...;
1369	as a stop gap to shield against fatal memory overflow (with large values).	1947	IO::AIO::poll_cb;
		1948	}
		1949
		1950	IO::AIO::flush;
		1951
		1952	The call to C<poll_cb> inside the loop will normally return instantly, but
		1953	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1954	some requests have been handled. This keeps the loop from pushing a large
		1955	number of C<aio_stat> requests onto the queue.
		1956
		1957	The default value for C<max_outstanding> is very large, so there is no
		1958	practical limit on the number of outstanding requests.
1370		1959
1371	=back	1960	=back
1372		1961
1373	=head3 STATISTICAL INFORMATION	1962	=head3 STATISTICAL INFORMATION
1374		1963
…		…
1394	Returns the number of requests currently in the pending state (executed,	1983	Returns the number of requests currently in the pending state (executed,
1395	but not yet processed by poll_cb).	1984	but not yet processed by poll_cb).
1396		1985
1397	=back	1986	=back
1398		1987
		1988	=head3 MISCELLANEOUS FUNCTIONS
		1989
		1990	IO::AIO implements some functions that are useful when you want to use
		1991	some "Advanced I/O" function not available to in Perl, without going the
		1992	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		1993	counterpart.
		1994
		1995	=over 4
		1996
		1997	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1998
		1999	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		2000	but is blocking (this makes most sense if you know the input data is
		2001	likely cached already and the output filehandle is set to non-blocking
		2002	operations).
		2003
		2004	Returns the number of bytes copied, or C<-1> on error.
		2005
		2006	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		2007
		2008	Simply calls the C<posix_fadvise> function (see its
		2009	manpage for details). The following advice constants are
		2010	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		2011	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		2012	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		2013
		2014	On systems that do not implement C<posix_fadvise>, this function returns
		2015	ENOSYS, otherwise the return value of C<posix_fadvise>.
		2016
		2017	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		2018
		2019	Simply calls the C<posix_madvise> function (see its
		2020	manpage for details). The following advice constants are
		2021	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		2022	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		2023
		2024	On systems that do not implement C<posix_madvise>, this function returns
		2025	ENOSYS, otherwise the return value of C<posix_madvise>.
		2026
		2027	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		2028
		2029	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		2030	$scalar (see its manpage for details). The following protect
		2031	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		2032	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2033
		2034	On systems that do not implement C<mprotect>, this function returns
		2035	ENOSYS, otherwise the return value of C<mprotect>.
		2036
		2037	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		2038
		2039	Memory-maps a file (or anonymous memory range) and attaches it to the
		2040	given C<$scalar>, which will act like a string scalar. Returns true on
		2041	success, and false otherwise.
		2042
		2043	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		2044	change the string length, and most read-only operations such as copying it
		2045	or searching it with regexes and so on.
		2046
		2047	Anything else is unsafe and will, at best, result in memory leaks.
		2048
		2049	The memory map associated with the C<$scalar> is automatically removed
		2050	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		2051	C<IO::AIO::munmap> functions are called.
		2052
		2053	This calls the C<mmap>(2) function internally. See your system's manual
		2054	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		2055
		2056	The C<$length> must be larger than zero and smaller than the actual
		2057	filesize.
		2058
		2059	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		2060	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		2061
		2062	C<$flags> can be a combination of
		2063	C<IO::AIO::MAP_SHARED> or
		2064	C<IO::AIO::MAP_PRIVATE>,
		2065	or a number of system-specific flags (when not available, the are C<0>):
		2066	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
		2067	C<IO::AIO::MAP_HUGETLB>,
		2068	C<IO::AIO::MAP_LOCKED>,
		2069	C<IO::AIO::MAP_NORESERVE>,
		2070	C<IO::AIO::MAP_POPULATE>,
		2071	C<IO::AIO::MAP_NONBLOCK>,
		2072	C<IO::AIO::MAP_FIXED>,
		2073	C<IO::AIO::MAP_GROWSDOWN>,
		2074	C<IO::AIO::MAP_32BIT>,
		2075	C<IO::AIO::MAP_HUGETLB> or
		2076	C<IO::AIO::MAP_STACK>.
		2077
		2078	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		2079
		2080	C<$offset> is the offset from the start of the file - it generally must be
		2081	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		2082
		2083	Example:
		2084
		2085	use Digest::MD5;
		2086	use IO::AIO;
		2087
		2088	open my $fh, "<verybigfile"
		2089	or die "$!";
		2090
		2091	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		2092	or die "verybigfile: $!";
		2093
		2094	my $fast_md5 = md5 $data;
		2095
		2096	=item IO::AIO::munmap $scalar
		2097
		2098	Removes a previous mmap and undefines the C<$scalar>.
		2099
		2100	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		2101
		2102	Calls the C<munlock> function, undoing the effects of a previous
		2103	C<aio_mlock> call (see its description for details).
		2104
		2105	=item IO::AIO::munlockall
		2106
		2107	Calls the C<munlockall> function.
		2108
		2109	On systems that do not implement C<munlockall>, this function returns
		2110	ENOSYS, otherwise the return value of C<munlockall>.
		2111
		2112	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2113
		2114	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2115	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2116	should be the file offset.
		2117
		2118	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2119	silently corrupt the data in this case.
		2120
		2121	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2122	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2123	C<IO::AIO::SPLICE_F_GIFT>.
		2124
		2125	See the C<splice(2)> manpage for details.
		2126
		2127	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2128
		2129	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2130	description for C<IO::AIO::splice> above for details.
		2131
		2132	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2133
		2134	Attempts to query or change the pipe buffer size. Obviously works only
		2135	on pipes, and currently works only on GNU/Linux systems, and fails with
		2136	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2137	size on other systems, drop me a note.
		2138
		2139	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2140
		2141	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2142	C<$flags> is missing or C<0>, then this should be the same as a call to
		2143	perl's built-in C<pipe> function and create a new pipe, and works on
		2144	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2145	(..., 4096, O_BINARY)>.
		2146
		2147	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2148	the given flags (Linux 2.6.27, glibc 2.9).
		2149
		2150	On success, the read and write file handles are returned.
		2151
		2152	On error, nothing will be returned. If the pipe2 syscall is missing and
		2153	C<$flags> is non-zero, fails with C<ENOSYS>.
		2154
		2155	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2156	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2157	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2158
		2159	=back
		2160
1399	=cut	2161	=cut
1400		2162
1401	min_parallel 8;	2163	min_parallel 8;
1402		2164
1403	END { flush }	2165	END { flush }
1404		2166
1405	1;	2167	1;
1406		2168
		2169	=head1 EVENT LOOP INTEGRATION
		2170
		2171	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		2172	automatically into many event loops:
		2173
		2174	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		2175	use AnyEvent::AIO;
		2176
		2177	You can also integrate IO::AIO manually into many event loops, here are
		2178	some examples of how to do this:
		2179
		2180	# EV integration
		2181	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		2182
		2183	# Event integration
		2184	Event->io (fd => IO::AIO::poll_fileno,
		2185	poll => 'r',
		2186	cb => \&IO::AIO::poll_cb);
		2187
		2188	# Glib/Gtk2 integration
		2189	add_watch Glib::IO IO::AIO::poll_fileno,
		2190	in => sub { IO::AIO::poll_cb; 1 };
		2191
		2192	# Tk integration
		2193	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		2194	readable => \&IO::AIO::poll_cb);
		2195
		2196	# Danga::Socket integration
		2197	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		2198	\&IO::AIO::poll_cb);
		2199
1407	=head2 FORK BEHAVIOUR	2200	=head2 FORK BEHAVIOUR
1408		2201
1409	This module should do "the right thing" when the process using it forks:	2202	Usage of pthreads in a program changes the semantics of fork
		2203	considerably. Specifically, only async-safe functions can be called after
		2204	fork. Perl doesn't know about this, so in general, you cannot call fork
		2205	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2206	pthreads, so this applies, but many other extensions and (for inexplicable
		2207	reasons) perl itself often is linked against pthreads, so this limitation
		2208	applies to quite a lot of perls.
1410		2209
1411	Before the fork, IO::AIO enters a quiescent state where no requests	2210	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1412	can be added in other threads and no results will be processed. After	2211	only works in the process that loaded it. Forking is fully supported, but
1413	the fork the parent simply leaves the quiescent state and continues	2212	using IO::AIO in the child is not.
1414	request/result processing, while the child frees the request/result queue
1415	(so that the requests started before the fork will only be handled in the
1416	parent). Threads will be started on demand until the limit set in the
1417	parent process has been reached again.
1418		2213
1419	In short: the parent will, after a short pause, continue as if fork had	2214	You might get around by not I<using> IO::AIO before (or after)
1420	not been called, while the child will act as if IO::AIO has not been used	2215	forking. You could also try to call the L<IO::AIO::reinit> function in the
1421	yet.	2216	child:
		2217
		2218	=over 4
		2219
		2220	=item IO::AIO::reinit
		2221
		2222	Abandons all current requests and I/O threads and simply reinitialises all
		2223	data structures. This is not an operation supported by any standards, but
		2224	happens to work on GNU/Linux and some newer BSD systems.
		2225
		2226	The only reasonable use for this function is to call it after forking, if
		2227	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2228	the process will result in undefined behaviour. Calling it at any time
		2229	will also result in any undefined (by POSIX) behaviour.
		2230
		2231	=back
1422		2232
1423	=head2 MEMORY USAGE	2233	=head2 MEMORY USAGE
1424		2234
1425	Per-request usage:	2235	Per-request usage:
1426		2236

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