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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.168 by root, Mon Nov 30 22:22:13 2009 UTC vs.
Revision 1.240 by root, Mon Dec 17 06:18:39 2012 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>
…		…
99		76
100	# register the IO::AIO callback with EV	77	# register the IO::AIO callback with EV
101	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
102		79
103	# queue the request to open /etc/passwd	80	# queue the request to open /etc/passwd
104	aio_open "/etc/passwd", O_RDONLY, 0, sub {	81	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
105	my $fh = shift	82	my $fh = shift
106	or die "error while opening: $!";	83	or die "error while opening: $!";
107		84
108	# stat'ing filehandles is generally non-blocking	85	# stat'ing filehandles is generally non-blocking
109	my $size = -s $fh;	86	my $size = -s $fh;
…		…
191	use common::sense;	168	use common::sense;
192		169
193	use base 'Exporter';	170	use base 'Exporter';
194		171
195	BEGIN {	172	BEGIN {
196	our $VERSION = '3.31';	173	our $VERSION = '4.18';
197		174
198	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	175	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	176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
200	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
201	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead	178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_allocate
		179	aio_pathsync aio_readahead aio_fiemap
202	aio_rename aio_link aio_move aio_copy aio_group	180	aio_rename aio_link aio_move aio_copy aio_group
203	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	181	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
204	aio_chmod aio_utime aio_truncate);	182	aio_chmod aio_utime aio_truncate
		183	aio_msync aio_mtouch aio_mlock aio_mlockall
		184	aio_statvfs
		185	aio_wd);
205		186
206	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	187	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
207	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	188	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
208	min_parallel max_parallel max_idle	189	min_parallel max_parallel max_idle idle_timeout
209	nreqs nready npending nthreads	190	nreqs nready npending nthreads
210	max_poll_time max_poll_reqs	191	max_poll_time max_poll_reqs
211	sendfile fadvise);	192	sendfile fadvise madvise
		193	mmap munmap munlock munlockall);
212		194
213	push @AIO_REQ, qw(aio_busy); # not exported	195	push @AIO_REQ, qw(aio_busy); # not exported
214		196
215	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	197	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
216		198
…		…
218	XSLoader::load ("IO::AIO", $VERSION);	200	XSLoader::load ("IO::AIO", $VERSION);
219	}	201	}
220		202
221	=head1 FUNCTIONS	203	=head1 FUNCTIONS
222		204
223	=head2 AIO REQUEST FUNCTIONS	205	=head2 QUICK OVERVIEW
		206
		207	This section simply lists the prototypes most of the functions for
		208	quick reference. See the following sections for function-by-function
		209	documentation.
		210
		211	aio_wd $pathname, $callback->($wd)
		212	aio_open $pathname, $flags, $mode, $callback->($fh)
		213	aio_close $fh, $callback->($status)
		214	aio_seek $fh,$offset,$whence, $callback->($offs)
		215	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		216	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		217	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		218	aio_readahead $fh,$offset,$length, $callback->($retval)
		219	aio_stat $fh_or_path, $callback->($status)
		220	aio_lstat $fh, $callback->($status)
		221	aio_statvfs $fh_or_path, $callback->($statvfs)
		222	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		223	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		224	aio_chmod $fh_or_path, $mode, $callback->($status)
		225	aio_truncate $fh_or_path, $offset, $callback->($status)
		226	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		227	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		228	aio_unlink $pathname, $callback->($status)
		229	aio_mknod $pathname, $mode, $dev, $callback->($status)
		230	aio_link $srcpath, $dstpath, $callback->($status)
		231	aio_symlink $srcpath, $dstpath, $callback->($status)
		232	aio_readlink $pathname, $callback->($link)
		233	aio_realpath $pathname, $callback->($link)
		234	aio_rename $srcpath, $dstpath, $callback->($status)
		235	aio_mkdir $pathname, $mode, $callback->($status)
		236	aio_rmdir $pathname, $callback->($status)
		237	aio_readdir $pathname, $callback->($entries)
		238	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		239	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		240	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		241	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		242	aio_load $pathname, $data, $callback->($status)
		243	aio_copy $srcpath, $dstpath, $callback->($status)
		244	aio_move $srcpath, $dstpath, $callback->($status)
		245	aio_rmtree $pathname, $callback->($status)
		246	aio_sync $callback->($status)
		247	aio_syncfs $fh, $callback->($status)
		248	aio_fsync $fh, $callback->($status)
		249	aio_fdatasync $fh, $callback->($status)
		250	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		251	aio_pathsync $pathname, $callback->($status)
		252	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		253	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		254	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		255	aio_mlockall $flags, $callback->($status)
		256	aio_group $callback->(...)
		257	aio_nop $callback->()
		258
		259	$prev_pri = aioreq_pri [$pri]
		260	aioreq_nice $pri_adjust
		261
		262	IO::AIO::poll_wait
		263	IO::AIO::poll_cb
		264	IO::AIO::poll
		265	IO::AIO::flush
		266	IO::AIO::max_poll_reqs $nreqs
		267	IO::AIO::max_poll_time $seconds
		268	IO::AIO::min_parallel $nthreads
		269	IO::AIO::max_parallel $nthreads
		270	IO::AIO::max_idle $nthreads
		271	IO::AIO::idle_timeout $seconds
		272	IO::AIO::max_outstanding $maxreqs
		273	IO::AIO::nreqs
		274	IO::AIO::nready
		275	IO::AIO::npending
		276
		277	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		278	IO::AIO::fadvise $fh, $offset, $len, $advice
		279	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		280	IO::AIO::munmap $scalar
		281	IO::AIO::madvise $scalar, $offset, $length, $advice
		282	IO::AIO::mprotect $scalar, $offset, $length, $protect
		283	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		284	IO::AIO::munlockall
		285
		286	=head2 API NOTES
224		287
225	All the C<aio_*> calls are more or less thin wrappers around the syscall	288	All the C<aio_*> calls are more or less thin wrappers around the syscall
226	with the same name (sans C<aio_>). The arguments are similar or identical,	289	with the same name (sans C<aio_>). The arguments are similar or identical,
227	and they all accept an additional (and optional) C<$callback> argument	290	and they all accept an additional (and optional) C<$callback> argument
228	which must be a code reference. This code reference will get called with	291	which must be a code reference. This code reference will be called after
229	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	292	the syscall has been executed in an asynchronous fashion. The results
230	perl, which usually delivers "false") as its sole argument after the given	293	of the request will be passed as arguments to the callback (and, if an
231	syscall has been executed asynchronously.	294	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		295	most syscalls return C<-1> on error, unlike perl, which usually delivers
		296	"false").
		297
		298	Some requests (such as C<aio_readdir>) pass the actual results and
		299	communicate failures by passing C<undef>.
232		300
233	All functions expecting a filehandle keep a copy of the filehandle	301	All functions expecting a filehandle keep a copy of the filehandle
234	internally until the request has finished.	302	internally until the request has finished.
235		303
236	All functions return request objects of type L<IO::AIO::REQ> that allow	304	All functions return request objects of type L<IO::AIO::REQ> that allow
237	further manipulation of those requests while they are in-flight.	305	further manipulation of those requests while they are in-flight.
238		306
239	The pathnames you pass to these routines I<must> be absolute and	307	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	308	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	309	current working directory could have changed. Alternatively, you can
242	changed. Alternatively, you can make sure that you never change the	310	make sure that you never change the current working directory anywhere
243	current working directory anywhere in the program and then use relative	311	in the program and then use relative paths. You can also take advantage
244	paths.	312	of IO::AIOs working directory abstraction, that lets you specify paths
		313	relative to some previously-opened "working directory object" - see the
		314	description of the C<IO::AIO::WD> class later in this document.
245		315
246	To encode pathnames as octets, either make sure you either: a) always pass	316	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	317	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	318	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	319	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)	320	effect in the user environment, d) use Glib::filename_from_unicode on
251	use something else to ensure your scalar has the correct contents.	321	unicode filenames or e) use something else to ensure your scalar has the
		322	correct contents.
252		323
253	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	324	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
254	handles correctly whether it is set or not.	325	handles correctly whether it is set or not.
		326
		327	=head2 AIO REQUEST FUNCTIONS
255		328
256	=over 4	329	=over 4
257		330
258	=item $prev_pri = aioreq_pri [$pri]	331	=item $prev_pri = aioreq_pri [$pri]
259		332
…		…
289		362
290		363
291	=item aio_open $pathname, $flags, $mode, $callback->($fh)	364	=item aio_open $pathname, $flags, $mode, $callback->($fh)
292		365
293	Asynchronously open or create a file and call the callback with a newly	366	Asynchronously open or create a file and call the callback with a newly
294	created filehandle for the file.	367	created filehandle for the file (or C<undef> in case of an error).
295		368
296	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	369	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
297	for an explanation.	370	for an explanation.
298		371
299	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	372	The C<$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	379	by the umask in effect then the request is being executed, so better never
307	change the umask.	380	change the umask.
308		381
309	Example:	382	Example:
310		383
311	aio_open "/etc/passwd", O_RDONLY, 0, sub {	384	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
312	if ($_[0]) {	385	if ($_[0]) {
313	print "open successful, fh is $_[0]\n";	386	print "open successful, fh is $_[0]\n";
314	...	387	...
315	} else {	388	} else {
316	die "open failed: $!\n";	389	die "open failed: $!\n";
317	}	390	}
318	};	391	};
319		392
		393	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		394	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		395	following POSIX and non-POSIX constants are available (missing ones on
		396	your system are, as usual, C<0>):
		397
		398	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		399	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		400	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		401
320		402
321	=item aio_close $fh, $callback->($status)	403	=item aio_close $fh, $callback->($status)
322		404
323	Asynchronously close a file and call the callback with the result	405	Asynchronously close a file and call the callback with the result
324	code.	406	code.
…		…
332		414
333	Or in other words: the file descriptor will be closed, but it will not be	415	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.	416	free for reuse until the perl filehandle is closed.
335		417
336	=cut	418	=cut
		419
		420	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		421
		422	Seeks the filehandle to the new C<$offset>, similarly to perl's
		423	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		424	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		425	C<IO::AIO::SEEK_END>).
		426
		427	The resulting absolute offset will be passed to the callback, or C<-1> in
		428	case of an error.
		429
		430	In theory, the C<$whence> constants could be different than the
		431	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		432	so don't panic.
		433
		434	As a GNU/Linux (and maybe Solaris) extension, also the constants
		435	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		436	could be found. No guarantees about suitability for use in C<aio_seek> or
		437	Perl's C<sysseek> can be made though, although I would naively assume they
		438	"just work".
337		439
338	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	440	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
339		441
340	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	442	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
341		443
…		…
374		476
375	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	477	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
376	reading at byte offset C<$in_offset>, and starts writing at the current	478	reading at byte offset C<$in_offset>, and starts writing at the current
377	file offset of C<$out_fh>. Because of that, it is not safe to issue more	479	file offset of C<$out_fh>. Because of that, it is not safe to issue more
378	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	480	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
379	other.	481	other. The same C<$in_fh> works fine though, as this function does not
		482	move or use the file offset of C<$in_fh>.
380		483
		484	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		485	are written, and there is no way to find out how many more bytes have been
		486	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		487	number of bytes written to C<$out_fh>. Only if the result value equals
		488	C<$length> one can assume that C<$length> bytes have been read.
		489
		490	Unlike with other C<aio_> functions, it makes a lot of sense to use
		491	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		492	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		493	the socket I/O will be non-blocking. Note, however, that you can run
		494	into a trap where C<aio_sendfile> reads some data with readahead, then
		495	fails to write all data, and when the socket is ready the next time, the
		496	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		497	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		498	resource usage.
		499
381	This call tries to make use of a native C<sendfile> syscall to provide	500	This call tries to make use of a native C<sendfile>-like syscall to
382	zero-copy operation. For this to work, C<$out_fh> should refer to a	501	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.	502	a socket, and C<$in_fh> should refer to an mmap'able file.
384		503
385	If the native sendfile call fails or is not implemented, it will be	504	If a native sendfile cannot be found or it fails with C<ENOSYS>,
386	emulated, so you can call C<aio_sendfile> on any type of filehandle	505	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		506	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
387	regardless of the limitations of the operating system.	507	type of filehandle regardless of the limitations of the operating system.
388		508
389	Please note, however, that C<aio_sendfile> can read more bytes from	509	As native sendfile syscalls (as practically any non-POSIX interface hacked
390	C<$in_fh> than are written, and there is no way to find out how many	510	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	511	on many systems, this implementation tries to work around some known bugs
392	provides the number of bytes written to C<$out_fh>. Only if the result	512	in Linux and FreeBSD kernels (probably others, too), but that might fail,
393	value equals C<$length> one can assume that C<$length> bytes have been	513	so you really really should check the return value of C<aio_sendfile> -
394	read.	514	fewre bytes than expected might have been transferred.
395		515
396		516
397	=item aio_readahead $fh,$offset,$length, $callback->($retval)	517	=item aio_readahead $fh,$offset,$length, $callback->($retval)
398		518
399	C<aio_readahead> populates the page cache with data from a file so that	519	C<aio_readahead> populates the page cache with data from a file so that
…		…
422		542
423	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	543	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	544	error when stat'ing a large file, the results will be silently truncated
425	unless perl itself is compiled with large file support.	545	unless perl itself is compiled with large file support.
426		546
		547	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		548	following constants and functions (if not implemented, the constants will
		549	be C<0> and the functions will either C<croak> or fall back on traditional
		550	behaviour).
		551
		552	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		553	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		554	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		555
427	Example: Print the length of F</etc/passwd>:	556	Example: Print the length of F</etc/passwd>:
428		557
429	aio_stat "/etc/passwd", sub {	558	aio_stat "/etc/passwd", sub {
430	$_[0] and die "stat failed: $!";	559	$_[0] and die "stat failed: $!";
431	print "size is ", -s _, "\n";	560	print "size is ", -s _, "\n";
432	};	561	};
433		562
434		563
		564	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		565
		566	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		567	whether a file handle or path was passed.
		568
		569	On success, the callback is passed a hash reference with the following
		570	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		571	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		572	is passed.
		573
		574	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		575	C<ST_NOSUID>.
		576
		577	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		578	their correct value when available, or to C<0> on systems that do
		579	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		580	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		581	C<ST_NODIRATIME> and C<ST_RELATIME>.
		582
		583	Example: stat C</wd> and dump out the data if successful.
		584
		585	aio_statvfs "/wd", sub {
		586	my $f = $_[0]
		587	or die "statvfs: $!";
		588
		589	use Data::Dumper;
		590	say Dumper $f;
		591	};
		592
		593	# result:
		594	{
		595	bsize => 1024,
		596	bfree => 4333064312,
		597	blocks => 10253828096,
		598	files => 2050765568,
		599	flag => 4096,
		600	favail => 2042092649,
		601	bavail => 4333064312,
		602	ffree => 2042092649,
		603	namemax => 255,
		604	frsize => 1024,
		605	fsid => 1810
		606	}
		607
		608	Here is a (likely partial) list of fsid values used by Linux - it is safe
		609	to hardcode these when the $^O is C<linux>:
		610
		611	0x0000adf5 adfs
		612	0x0000adff affs
		613	0x5346414f afs
		614	0x09041934 anon-inode filesystem
		615	0x00000187 autofs
		616	0x42465331 befs
		617	0x1badface bfs
		618	0x42494e4d binfmt_misc
		619	0x9123683e btrfs
		620	0x0027e0eb cgroupfs
		621	0xff534d42 cifs
		622	0x73757245 coda
		623	0x012ff7b7 coh
		624	0x28cd3d45 cramfs
		625	0x453dcd28 cramfs-wend (wrong endianness)
		626	0x64626720 debugfs
		627	0x00001373 devfs
		628	0x00001cd1 devpts
		629	0x0000f15f ecryptfs
		630	0x00414a53 efs
		631	0x0000137d ext
		632	0x0000ef53 ext2/ext3
		633	0x0000ef51 ext2
		634	0x00004006 fat
		635	0x65735546 fuseblk
		636	0x65735543 fusectl
		637	0x0bad1dea futexfs
		638	0x01161970 gfs2
		639	0x47504653 gpfs
		640	0x00004244 hfs
		641	0xf995e849 hpfs
		642	0x958458f6 hugetlbfs
		643	0x2bad1dea inotifyfs
		644	0x00009660 isofs
		645	0x000072b6 jffs2
		646	0x3153464a jfs
		647	0x6b414653 k-afs
		648	0x0bd00bd0 lustre
		649	0x0000137f minix
		650	0x0000138f minix 30 char names
		651	0x00002468 minix v2
		652	0x00002478 minix v2 30 char names
		653	0x00004d5a minix v3
		654	0x19800202 mqueue
		655	0x00004d44 msdos
		656	0x0000564c novell
		657	0x00006969 nfs
		658	0x6e667364 nfsd
		659	0x00003434 nilfs
		660	0x5346544e ntfs
		661	0x00009fa1 openprom
		662	0x7461636F ocfs2
		663	0x00009fa0 proc
		664	0x6165676c pstorefs
		665	0x0000002f qnx4
		666	0x858458f6 ramfs
		667	0x52654973 reiserfs
		668	0x00007275 romfs
		669	0x67596969 rpc_pipefs
		670	0x73636673 securityfs
		671	0xf97cff8c selinux
		672	0x0000517b smb
		673	0x534f434b sockfs
		674	0x73717368 squashfs
		675	0x62656572 sysfs
		676	0x012ff7b6 sysv2
		677	0x012ff7b5 sysv4
		678	0x01021994 tmpfs
		679	0x15013346 udf
		680	0x00011954 ufs
		681	0x54190100 ufs byteswapped
		682	0x00009fa2 usbdevfs
		683	0x01021997 v9fs
		684	0xa501fcf5 vxfs
		685	0xabba1974 xenfs
		686	0x012ff7b4 xenix
		687	0x58465342 xfs
		688	0x012fd16d xia
		689
435	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	690	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
436		691
437	Works like perl's C<utime> function (including the special case of $atime	692	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	693	and $mtime being undef). Fractional times are supported if the underlying
439	syscalls support them.	694	syscalls support them.
…		…
466	=item aio_truncate $fh_or_path, $offset, $callback->($status)	721	=item aio_truncate $fh_or_path, $offset, $callback->($status)
467		722
468	Works like truncate(2) or ftruncate(2).	723	Works like truncate(2) or ftruncate(2).
469		724
470		725
		726	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		727
		728	Allocates or freed disk space according to the C<$mode> argument. See the
		729	linux C<fallocate> docuemntation for details.
		730
		731	C<$mode> can currently be C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE>
		732	to allocate space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE |
		733	IO::AIO::FALLOC_FL_KEEP_SIZE>, to deallocate a file range.
		734
		735	The file system block size used by C<fallocate> is presumably the
		736	C<f_bsize> returned by C<statvfs>.
		737
		738	If C<fallocate> isn't available or cannot be emulated (currently no
		739	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		740
		741
471	=item aio_chmod $fh_or_path, $mode, $callback->($status)	742	=item aio_chmod $fh_or_path, $mode, $callback->($status)
472		743
473	Works like perl's C<chmod> function.	744	Works like perl's C<chmod> function.
474		745
475		746
…		…
477		748
478	Asynchronously unlink (delete) a file and call the callback with the	749	Asynchronously unlink (delete) a file and call the callback with the
479	result code.	750	result code.
480		751
481		752
482	=item aio_mknod $path, $mode, $dev, $callback->($status)	753	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
483		754
484	[EXPERIMENTAL]	755	[EXPERIMENTAL]
485		756
486	Asynchronously create a device node (or fifo). See mknod(2).	757	Asynchronously create a device node (or fifo). See mknod(2).
487		758
488	The only (POSIX-) portable way of calling this function is:	759	The only (POSIX-) portable way of calling this function is:
489		760
490	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	761	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
491		762
		763	See C<aio_stat> for info about some potentially helpful extra constants
		764	and functions.
492		765
493	=item aio_link $srcpath, $dstpath, $callback->($status)	766	=item aio_link $srcpath, $dstpath, $callback->($status)
494		767
495	Asynchronously create a new link to the existing object at C<$srcpath> at	768	Asynchronously create a new link to the existing object at C<$srcpath> at
496	the path C<$dstpath> and call the callback with the result code.	769	the path C<$dstpath> and call the callback with the result code.
…		…
500		773
501	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	774	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
502	the path C<$dstpath> and call the callback with the result code.	775	the path C<$dstpath> and call the callback with the result code.
503		776
504		777
505	=item aio_readlink $path, $callback->($link)	778	=item aio_readlink $pathname, $callback->($link)
506		779
507	Asynchronously read the symlink specified by C<$path> and pass it to	780	Asynchronously read the symlink specified by C<$path> and pass it to
508	the callback. If an error occurs, nothing or undef gets passed to the	781	the callback. If an error occurs, nothing or undef gets passed to the
509	callback.	782	callback.
510		783
511		784
		785	=item aio_realpath $pathname, $callback->($path)
		786
		787	Asynchronously make the path absolute and resolve any symlinks in
		788	C<$path>. The resulting path only consists of directories (same as
		789	L<Cwd::realpath>).
		790
		791	This request can be used to get the absolute path of the current working
		792	directory by passing it a path of F<.> (a single dot).
		793
		794
512	=item aio_rename $srcpath, $dstpath, $callback->($status)	795	=item aio_rename $srcpath, $dstpath, $callback->($status)
513		796
514	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	797	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
515	rename(2) and call the callback with the result code.	798	rename(2) and call the callback with the result code.
516		799
…		…
538	array-ref with the filenames.	821	array-ref with the filenames.
539		822
540		823
541	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	824	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
542		825
543	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	826	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	827	tune behaviour and output format. In case of an error, C<$entries> will be
545	C<undef>.	828	C<undef>.
546		829
547	The flags are a combination of the following constants, ORed together (the	830	The flags are a combination of the following constants, ORed together (the
548	flags will also be passed to the callback, possibly modified):	831	flags will also be passed to the callback, possibly modified):
549		832
550	=over 4	833	=over 4
551		834
552	=item IO::AIO::READDIR_DENTS	835	=item IO::AIO::READDIR_DENTS
553		836
554	When this flag is off, then the callback gets an arrayref with of names	837	When this flag is off, then the callback gets an arrayref consisting of
555	only (as with C<aio_readdir>), otherwise it gets an arrayref with	838	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
556	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	839	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
557	entry in more detail.	840	entry in more detail.
558		841
559	C<$name> is the name of the entry.	842	C<$name> is the name of the entry.
560		843
…		…
573	systems that do not deliver the inode information.	856	systems that do not deliver the inode information.
574		857
575	=item IO::AIO::READDIR_DIRS_FIRST	858	=item IO::AIO::READDIR_DIRS_FIRST
576		859
577	When this flag is set, then the names will be returned in an order where	860	When this flag is set, then the names will be returned in an order where
578	likely directories come first. This is useful when you need to quickly	861	likely directories come first, in optimal stat order. This is useful when
579	find directories, or you want to find all directories while avoiding to	862	you need to quickly find directories, or you want to find all directories
580	stat() each entry.	863	while avoiding to stat() each entry.
581		864
582	If the system returns type information in readdir, then this is used	865	If the system returns type information in readdir, then this is used
583	to find directories directly. Otherwise, likely directories are files	866	to find directories directly. Otherwise, likely directories are names
584	beginning with ".", or otherwise files with no dots, of which files with	867	beginning with ".", or otherwise names with no dots, of which names with
585	short names are tried first.	868	short names are tried first.
586		869
587	=item IO::AIO::READDIR_STAT_ORDER	870	=item IO::AIO::READDIR_STAT_ORDER
588		871
589	When this flag is set, then the names will be returned in an order	872	When this flag is set, then the names will be returned in an order
…		…
596		879
597	=item IO::AIO::READDIR_FOUND_UNKNOWN	880	=item IO::AIO::READDIR_FOUND_UNKNOWN
598		881
599	This flag should not be set when calling C<aio_readdirx>. Instead, it	882	This flag should not be set when calling C<aio_readdirx>. Instead, it
600	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	883	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
601	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	884	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
602	C<$type>'s are known, which can be used to speed up some algorithms.	885	C<$type>'s are known, which can be used to speed up some algorithms.
603		886
604	=back	887	=back
605		888
606		889
607	=item aio_load $path, $data, $callback->($status)	890	=item aio_load $pathname, $data, $callback->($status)
608		891
609	This is a composite request that tries to fully load the given file into	892	This is a composite request that tries to fully load the given file into
610	memory. Status is the same as with aio_read.	893	memory. Status is the same as with aio_read.
611		894
612	=cut	895	=cut
…		…
734	if ($_[0] && $! == EXDEV) {	1017	if ($_[0] && $! == EXDEV) {
735	aioreq_pri $pri;	1018	aioreq_pri $pri;
736	add $grp aio_copy $src, $dst, sub {	1019	add $grp aio_copy $src, $dst, sub {
737	$grp->result ($_[0]);	1020	$grp->result ($_[0]);
738		1021
739	if (!$_[0]) {	1022	unless ($_[0]) {
740	aioreq_pri $pri;	1023	aioreq_pri $pri;
741	add $grp aio_unlink $src;	1024	add $grp aio_unlink $src;
742	}	1025	}
743	};	1026	};
744	} else {	1027	} else {
…		…
747	};	1030	};
748		1031
749	$grp	1032	$grp
750	}	1033	}
751		1034
752	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1035	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
753		1036
754	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1037	Scans a directory (similar to C<aio_readdir>) but additionally tries to
755	efficiently separate the entries of directory C<$path> into two sets of	1038	efficiently separate the entries of directory C<$path> into two sets of
756	names, directories you can recurse into (directories), and ones you cannot	1039	names, directories you can recurse into (directories), and ones you cannot
757	recurse into (everything else, including symlinks to directories).	1040	recurse into (everything else, including symlinks to directories).
…		…
788	Then entries will be sorted into likely directories a non-initial dot	1071	Then entries will be sorted into likely directories a non-initial dot
789	currently) and likely non-directories (see C<aio_readdirx>). Then every	1072	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,	1073	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	1074	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	1075	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	1076	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	1077	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	1078	data (e.g. ext2fs filetype feature), even on systems that cannot return
796	the filetype information on readdir.	1079	the filetype information on readdir.
797		1080
798	If the known number of directories (link count - 2) has been reached, the	1081	If the known number of directories (link count - 2) has been reached, the
…		…
814		1097
815	my $grp = aio_group $cb;	1098	my $grp = aio_group $cb;
816		1099
817	$maxreq = 4 if $maxreq <= 0;	1100	$maxreq = 4 if $maxreq <= 0;
818		1101
819	# stat once	1102	# get a wd object
820	aioreq_pri $pri;	1103	aioreq_pri $pri;
821	add $grp aio_stat $path, sub {	1104	add $grp aio_wd $path, sub {
		1105	$_[0]
822	return $grp->result () if $_[0];	1106	or return $grp->result ();
823	my $now = time;
824	my $hash1 = join ":", (stat _)[0,1,3,7,9];
825		1107
826	# read the directory entries	1108	my $wd = [shift, "."];
		1109
		1110	# stat once
827	aioreq_pri $pri;	1111	aioreq_pri $pri;
828	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1112	add $grp aio_stat $wd, sub {
829	my $entries = shift
830	or return $grp->result ();	1113	return $grp->result () if $_[0];
		1114	my $now = time;
		1115	my $hash1 = join ":", (stat _)[0,1,3,7,9];
831		1116
832	# stat the dir another time	1117	# read the directory entries
833	aioreq_pri $pri;	1118	aioreq_pri $pri;
		1119	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1120	my $entries = shift
		1121	or return $grp->result ();
		1122
		1123	# stat the dir another time
		1124	aioreq_pri $pri;
834	add $grp aio_stat $path, sub {	1125	add $grp aio_stat $wd, sub {
835	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1126	my $hash2 = join ":", (stat _)[0,1,3,7,9];
836		1127
837	my $ndirs;	1128	my $ndirs;
838		1129
839	# take the slow route if anything looks fishy	1130	# take the slow route if anything looks fishy
840	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1131	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
841	$ndirs = -1;	1132	$ndirs = -1;
842	} else {	1133	} else {
843	# if nlink == 2, we are finished	1134	# if nlink == 2, we are finished
844	# for non-posix-fs's, we rely on nlink < 2	1135	# for non-posix-fs's, we rely on nlink < 2
845	$ndirs = (stat _)[3] - 2	1136	$ndirs = (stat _)[3] - 2
846	or return $grp->result ([], $entries);	1137	or return $grp->result ([], $entries);
847	}	1138	}
848		1139
849	my (@dirs, @nondirs);	1140	my (@dirs, @nondirs);
850		1141
851	my $statgrp = add $grp aio_group sub {	1142	my $statgrp = add $grp aio_group sub {
852	$grp->result (\@dirs, \@nondirs);	1143	$grp->result (\@dirs, \@nondirs);
853	};	1144	};
854		1145
855	limit $statgrp $maxreq;	1146	limit $statgrp $maxreq;
856	feed $statgrp sub {	1147	feed $statgrp sub {
857	return unless @$entries;	1148	return unless @$entries;
858	my $entry = shift @$entries;	1149	my $entry = shift @$entries;
859		1150
860	aioreq_pri $pri;	1151	aioreq_pri $pri;
		1152	$wd->[1] = "$entry/.";
861	add $statgrp aio_stat "$path/$entry/.", sub {	1153	add $statgrp aio_stat $wd, sub {
862	if ($_[0] < 0) {	1154	if ($_[0] < 0) {
863	push @nondirs, $entry;	1155	push @nondirs, $entry;
864	} else {	1156	} else {
865	# need to check for real directory	1157	# need to check for real directory
866	aioreq_pri $pri;	1158	aioreq_pri $pri;
		1159	$wd->[1] = $entry;
867	add $statgrp aio_lstat "$path/$entry", sub {	1160	add $statgrp aio_lstat $wd, sub {
868	if (-d _) {	1161	if (-d _) {
869	push @dirs, $entry;	1162	push @dirs, $entry;
870		1163
871	unless (--$ndirs) {	1164	unless (--$ndirs) {
872	push @nondirs, @$entries;	1165	push @nondirs, @$entries;
873	feed $statgrp;	1166	feed $statgrp;
		1167	}
		1168	} else {
		1169	push @nondirs, $entry;
874	}	1170	}
875	} else {
876	push @nondirs, $entry;
877	}	1171	}
878	}	1172	}
879	}	1173	};
880	};	1174	};
881	};	1175	};
882	};	1176	};
883	};	1177	};
884	};	1178	};
885		1179
886	$grp	1180	$grp
887	}	1181	}
888		1182
889	=item aio_rmtree $path, $callback->($status)	1183	=item aio_rmtree $pathname, $callback->($status)
890		1184
891	Delete a directory tree starting (and including) C<$path>, return the	1185	Delete a directory tree starting (and including) C<$path>, return the
892	status of the final C<rmdir> only. This is a composite request that	1186	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	1187	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
894	everything else.	1188	everything else.
895		1189
896	=cut	1190	=cut
897		1191
…		…
936	callback with the fdatasync result code.	1230	callback with the fdatasync result code.
937		1231
938	If this call isn't available because your OS lacks it or it couldn't be	1232	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.	1233	detected, it will be emulated by calling C<fsync> instead.
940		1234
		1235	=item aio_syncfs $fh, $callback->($status)
		1236
		1237	Asynchronously call the syncfs syscall to sync the filesystem associated
		1238	to the given filehandle and call the callback with the syncfs result
		1239	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1240	errno to C<ENOSYS> nevertheless.
		1241
941	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1242	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
942		1243
943	Sync the data portion of the file specified by C<$offset> and C<$length>	1244	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	1245	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	1246	sync_file_range call. If sync_file_range is not available or it returns
…		…
948	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1249	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
949	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1250	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
950	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1251	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
951	manpage for details.	1252	manpage for details.
952		1253
953	=item aio_pathsync $path, $callback->($status)	1254	=item aio_pathsync $pathname, $callback->($status)
954		1255
955	This request tries to open, fsync and close the given path. This is a	1256	This request tries to open, fsync and close the given path. This is a
956	composite request intended to sync directories after directory operations	1257	composite request intended to sync directories after directory operations
957	(E.g. rename). This might not work on all operating systems or have any	1258	(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	1259	specific effect, but usually it makes sure that directory changes get
…		…
989	};	1290	};
990		1291
991	$grp	1292	$grp
992	}	1293	}
993		1294
		1295	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1296
		1297	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1298	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1299	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1300	scalar must only be modified in-place while an aio operation is pending on
		1301	it).
		1302
		1303	It calls the C<msync> function of your OS, if available, with the memory
		1304	area starting at C<$offset> in the string and ending C<$length> bytes
		1305	later. If C<$length> is negative, counts from the end, and if C<$length>
		1306	is C<undef>, then it goes till the end of the string. The flags can be
		1307	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1308	C<IO::AIO::MS_SYNC>.
		1309
		1310	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1311
		1312	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1313	scalars.
		1314
		1315	It touches (reads or writes) all memory pages in the specified
		1316	range inside the scalar. All caveats and parameters are the same
		1317	as for C<aio_msync>, above, except for flags, which must be either
		1318	C<0> (which reads all pages and ensures they are instantiated) or
		1319	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
		1320	writing an octet from it, which dirties the page).
		1321
		1322	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1323
		1324	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1325	scalars.
		1326
		1327	It reads in all the pages of the underlying storage into memory (if any)
		1328	and locks them, so they are not getting swapped/paged out or removed.
		1329
		1330	If C<$length> is undefined, then the scalar will be locked till the end.
		1331
		1332	On systems that do not implement C<mlock>, this function returns C<-1>
		1333	and sets errno to C<ENOSYS>.
		1334
		1335	Note that the corresponding C<munlock> is synchronous and is
		1336	documented under L<MISCELLANEOUS FUNCTIONS>.
		1337
		1338	Example: open a file, mmap and mlock it - both will be undone when
		1339	C<$data> gets destroyed.
		1340
		1341	open my $fh, "<", $path or die "$path: $!";
		1342	my $data;
		1343	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1344	aio_mlock $data; # mlock in background
		1345
		1346	=item aio_mlockall $flags, $callback->($status)
		1347
		1348	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1349	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1350
		1351	On systems that do not implement C<mlockall>, this function returns C<-1>
		1352	and sets errno to C<ENOSYS>.
		1353
		1354	Note that the corresponding C<munlockall> is synchronous and is
		1355	documented under L<MISCELLANEOUS FUNCTIONS>.
		1356
		1357	Example: asynchronously lock all current and future pages into memory.
		1358
		1359	aio_mlockall IO::AIO::MCL_FUTURE;
		1360
		1361	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1362
		1363	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1364	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1365	the ioctl is not available on your OS, then this request will fail with
		1366	C<ENOSYS>.
		1367
		1368	C<$start> is the starting offset to query extents for, C<$length> is the
		1369	size of the range to query - if it is C<undef>, then the whole file will
		1370	be queried.
		1371
		1372	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1373	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1374	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1375	the data portion.
		1376
		1377	C<$count> is the maximum number of extent records to return. If it is
		1378	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1379	case, if it is C<0>, then the callback receives the number of extents
		1380	instead of the extents themselves (which is unreliable, see below).
		1381
		1382	If an error occurs, the callback receives no arguments. The special
		1383	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1384
		1385	Otherwise, the callback receives an array reference with extent
		1386	structures. Each extent structure is an array reference itself, with the
		1387	following members:
		1388
		1389	[$logical, $physical, $length, $flags]
		1390
		1391	Flags is any combination of the following flag values (typically either C<0>
		1392	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1393
		1394	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1395	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1396	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1397	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1398	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1399	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1400
		1401	At the time of this writing (Linux 3.2), this requets is unreliable unless
		1402	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1403	it to return all extents of a range for files with large number of
		1404	extents. The code works around all these issues if C<$count> is undef.
		1405
994	=item aio_group $callback->(...)	1406	=item aio_group $callback->(...)
995		1407
996	This is a very special aio request: Instead of doing something, it is a	1408	This is a very special aio request: Instead of doing something, it is a
997	container for other aio requests, which is useful if you want to bundle	1409	container for other aio requests, which is useful if you want to bundle
998	many requests into a single, composite, request with a definite callback	1410	many requests into a single, composite, request with a definite callback
…		…
1034	like sleep and file handle readable/writable, the overhead this creates is	1446	like sleep and file handle readable/writable, the overhead this creates is
1035	immense (it blocks a thread for a long time) so do not use this function	1447	immense (it blocks a thread for a long time) so do not use this function
1036	except to put your application under artificial I/O pressure.	1448	except to put your application under artificial I/O pressure.
1037		1449
1038	=back	1450	=back
		1451
		1452
		1453	=head2 IO::AIO::WD - multiple working directories
		1454
		1455	Your process only has one current working directory, which is used by all
		1456	threads. This makes it hard to use relative paths (some other component
		1457	could call C<chdir> at any time, and it is hard to control when the path
		1458	will be used by IO::AIO).
		1459
		1460	One solution for this is to always use absolute paths. This usually works,
		1461	but can be quite slow (the kernel has to walk the whole path on every
		1462	access), and can also be a hassle to implement.
		1463
		1464	Newer POSIX systems have a number of functions (openat, fdopendir,
		1465	futimensat and so on) that make it possible to specify working directories
		1466	per operation.
		1467
		1468	For portability, and because the clowns who "designed", or shall I write,
		1469	perpetrated this new interface were obviously half-drunk, this abstraction
		1470	cannot be perfect, though.
		1471
		1472	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1473	object. This object stores the canonicalised, absolute version of the
		1474	path, and on systems that allow it, also a directory file descriptor.
		1475
		1476	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1477	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1478	object and a pathname instead (or the IO::AIO::WD object alone, which
		1479	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1480	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1481	to that IO::AIO::WD object.
		1482
		1483	For example, to get a wd object for F</etc> and then stat F<passwd>
		1484	inside, you would write:
		1485
		1486	aio_wd "/etc", sub {
		1487	my $etcdir = shift;
		1488
		1489	# although $etcdir can be undef on error, there is generally no reason
		1490	# to check for errors here, as aio_stat will fail with ENOENT
		1491	# when $etcdir is undef.
		1492
		1493	aio_stat [$etcdir, "passwd"], sub {
		1494	# yay
		1495	};
		1496	};
		1497
		1498	That C<aio_wd> is a request and not a normal function shows that creating
		1499	an IO::AIO::WD object is itself a potentially blocking operation, which is
		1500	why it is done asynchronously.
		1501
		1502	To stat the directory obtained with C<aio_wd> above, one could write
		1503	either of the following three request calls:
		1504
		1505	aio_lstat "/etc" , sub { ... # pathname as normal string
		1506	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1507	aio_lstat $wd , sub { ... # shorthand for the previous
		1508
		1509	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1510	object and the pathname string, so you could write the following without
		1511	causing any issues due to C<$path> getting reused:
		1512
		1513	my $path = [$wd, undef];
		1514
		1515	for my $name (qw(abc def ghi)) {
		1516	$path->[1] = $name;
		1517	aio_stat $path, sub {
		1518	# ...
		1519	};
		1520	}
		1521
		1522	There are some caveats: when directories get renamed (or deleted), the
		1523	pathname string doesn't change, so will point to the new directory (or
		1524	nowhere at all), while the directory fd, if available on the system,
		1525	will still point to the original directory. Most functions accepting a
		1526	pathname will use the directory fd on newer systems, and the string on
		1527	older systems. Some functions (such as realpath) will always rely on the
		1528	string form of the pathname.
		1529
		1530	So this functionality is mainly useful to get some protection against
		1531	C<chdir>, to easily get an absolute path out of a relative path for future
		1532	reference, and to speed up doing many operations in the same directory
		1533	(e.g. when stat'ing all files in a directory).
		1534
		1535	The following functions implement this working directory abstraction:
		1536
		1537	=over 4
		1538
		1539	=item aio_wd $pathname, $callback->($wd)
		1540
		1541	Asynchonously canonicalise the given pathname and convert it to an
		1542	IO::AIO::WD object representing it. If possible and supported on the
		1543	system, also open a directory fd to speed up pathname resolution relative
		1544	to this working directory.
		1545
		1546	If something goes wrong, then C<undef> is passwd to the callback instead
		1547	of a working directory object and C<$!> is set appropriately. Since
		1548	passing C<undef> as working directory component of a pathname fails the
		1549	request with C<ENOENT>, there is often no need for error checking in the
		1550	C<aio_wd> callback, as future requests using the value will fail in the
		1551	expected way.
		1552
		1553	If this call isn't available because your OS lacks it or it couldn't be
		1554	detected, it will be emulated by calling C<fsync> instead.
		1555
		1556	=item IO::AIO::CWD
		1557
		1558	This is a compiletime constant (object) that represents the process
		1559	current working directory.
		1560
		1561	Specifying this object as working directory object for a pathname is as if
		1562	the pathname would be specified directly, without a directory object. For
		1563	example, these calls are functionally identical:
		1564
		1565	aio_stat "somefile", sub { ... };
		1566	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1567
		1568	=back
		1569
		1570	To recover the path associated with an IO::AIO::WD object, you can use
		1571	C<aio_realpath>:
		1572
		1573	aio_realpath $wd, sub {
		1574	warn "path is $_[0]\n";
		1575	};
		1576
1039		1577
1040	=head2 IO::AIO::REQ CLASS	1578	=head2 IO::AIO::REQ CLASS
1041		1579
1042	All non-aggregate C<aio_*> functions return an object of this class when	1580	All non-aggregate C<aio_*> functions return an object of this class when
1043	called in non-void context.	1581	called in non-void context.
…		…
1161		1699
1162	Sets a feeder/generator on this group: every group can have an attached	1700	Sets a feeder/generator on this group: every group can have an attached
1163	generator that generates requests if idle. The idea behind this is that,	1701	generator that generates requests if idle. The idea behind this is that,
1164	although you could just queue as many requests as you want in a group,	1702	although you could just queue as many requests as you want in a group,
1165	this might starve other requests for a potentially long time. For example,	1703	this might starve other requests for a potentially long time. For example,
1166	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1704	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1167	delaying any later requests for a long time.	1705	requests, delaying any later requests for a long time.
1168		1706
1169	To avoid this, and allow incremental generation of requests, you can	1707	To avoid this, and allow incremental generation of requests, you can
1170	instead a group and set a feeder on it that generates those requests. The	1708	instead a group and set a feeder on it that generates those requests. The
1171	feed callback will be called whenever there are few enough (see C<limit>,	1709	feed callback will be called whenever there are few enough (see C<limit>,
1172	below) requests active in the group itself and is expected to queue more	1710	below) requests active in the group itself and is expected to queue more
…		…
1221		1759
1222	See C<poll_cb> for an example.	1760	See C<poll_cb> for an example.
1223		1761
1224	=item IO::AIO::poll_cb	1762	=item IO::AIO::poll_cb
1225		1763
1226	Process some outstanding events on the result pipe. You have to call this	1764	Process some requests that have reached the result phase (i.e. they have
1227	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1765	been executed but the results are not yet reported). You have to call
1228	returned earlier for whatever reason. Returns immediately when no events	1766	this "regularly" to finish outstanding requests.
1229	are outstanding. The amount of events processed depends on the settings of
1230	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1231		1767
		1768	Returns C<0> if all events could be processed (or there were no
		1769	events to process), or C<-1> if it returned earlier for whatever
		1770	reason. Returns immediately when no events are outstanding. The amount
		1771	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
		1772	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
		1773
1232	If not all requests were processed for whatever reason, the filehandle	1774	If not all requests were processed for whatever reason, the poll file
1233	will still be ready when C<poll_cb> returns, so normally you don't have to	1775	descriptor will still be ready when C<poll_cb> returns, so normally you
1234	do anything special to have it called later.	1776	don't have to do anything special to have it called later.
		1777
		1778	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1779	ready, it can be beneficial to call this function from loops which submit
		1780	a lot of requests, to make sure the results get processed when they become
		1781	available and not just when the loop is finished and the event loop takes
		1782	over again. This function returns very fast when there are no outstanding
		1783	requests.
1235		1784
1236	Example: Install an Event watcher that automatically calls	1785	Example: Install an Event watcher that automatically calls
1237	IO::AIO::poll_cb with high priority (more examples can be found in the	1786	IO::AIO::poll_cb with high priority (more examples can be found in the
1238	SYNOPSIS section, at the top of this document):	1787	SYNOPSIS section, at the top of this document):
1239		1788
1240	Event->io (fd => IO::AIO::poll_fileno,	1789	Event->io (fd => IO::AIO::poll_fileno,
1241	poll => 'r', async => 1,	1790	poll => 'r', async => 1,
1242	cb => \&IO::AIO::poll_cb);	1791	cb => \&IO::AIO::poll_cb);
		1792
		1793	=item IO::AIO::poll_wait
		1794
		1795	Wait until either at least one request is in the result phase or no
		1796	requests are outstanding anymore.
		1797
		1798	This is useful if you want to synchronously wait for some requests to
		1799	become ready, without actually handling them.
		1800
		1801	See C<nreqs> for an example.
		1802
		1803	=item IO::AIO::poll
		1804
		1805	Waits until some requests have been handled.
		1806
		1807	Returns the number of requests processed, but is otherwise strictly
		1808	equivalent to:
		1809
		1810	IO::AIO::poll_wait, IO::AIO::poll_cb
		1811
		1812	=item IO::AIO::flush
		1813
		1814	Wait till all outstanding AIO requests have been handled.
		1815
		1816	Strictly equivalent to:
		1817
		1818	IO::AIO::poll_wait, IO::AIO::poll_cb
		1819	while IO::AIO::nreqs;
1243		1820
1244	=item IO::AIO::max_poll_reqs $nreqs	1821	=item IO::AIO::max_poll_reqs $nreqs
1245		1822
1246	=item IO::AIO::max_poll_time $seconds	1823	=item IO::AIO::max_poll_time $seconds
1247		1824
…		…
1272	# use a low priority so other tasks have priority	1849	# use a low priority so other tasks have priority
1273	Event->io (fd => IO::AIO::poll_fileno,	1850	Event->io (fd => IO::AIO::poll_fileno,
1274	poll => 'r', nice => 1,	1851	poll => 'r', nice => 1,
1275	cb => &IO::AIO::poll_cb);	1852	cb => &IO::AIO::poll_cb);
1276		1853
1277	=item IO::AIO::poll_wait
1278
1279	If there are any outstanding requests and none of them in the result
1280	phase, wait till the result filehandle becomes ready for reading (simply
1281	does a C<select> on the filehandle. This is useful if you want to
1282	synchronously wait for some requests to finish).
1283
1284	See C<nreqs> for an example.
1285
1286	=item IO::AIO::poll
1287
1288	Waits until some requests have been handled.
1289
1290	Returns the number of requests processed, but is otherwise strictly
1291	equivalent to:
1292
1293	IO::AIO::poll_wait, IO::AIO::poll_cb
1294
1295	=item IO::AIO::flush
1296
1297	Wait till all outstanding AIO requests have been handled.
1298
1299	Strictly equivalent to:
1300
1301	IO::AIO::poll_wait, IO::AIO::poll_cb
1302	while IO::AIO::nreqs;
1303
1304	=back	1854	=back
1305		1855
1306	=head3 CONTROLLING THE NUMBER OF THREADS	1856	=head3 CONTROLLING THE NUMBER OF THREADS
1307		1857
1308	=over	1858	=over
…		…
1341		1891
1342	Under normal circumstances you don't need to call this function.	1892	Under normal circumstances you don't need to call this function.
1343		1893
1344	=item IO::AIO::max_idle $nthreads	1894	=item IO::AIO::max_idle $nthreads
1345		1895
1346	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1896	Limit the number of threads (default: 4) that are allowed to idle
1347	threads that did not get a request to process within 10 seconds). That	1897	(i.e., threads that did not get a request to process within the idle
1348	means if a thread becomes idle while C<$nthreads> other threads are also	1898	timeout (default: 10 seconds). That means if a thread becomes idle while
1349	idle, it will free its resources and exit.	1899	C<$nthreads> other threads are also idle, it will free its resources and
		1900	exit.
1350		1901
1351	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1902	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1352	to allow for extremely high load situations, but want to free resources	1903	to allow for extremely high load situations, but want to free resources
1353	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1904	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1354		1905
1355	The default is probably ok in most situations, especially if thread	1906	The default is probably ok in most situations, especially if thread
1356	creation is fast. If thread creation is very slow on your system you might	1907	creation is fast. If thread creation is very slow on your system you might
1357	want to use larger values.	1908	want to use larger values.
1358		1909
		1910	=item IO::AIO::idle_timeout $seconds
		1911
		1912	Sets the minimum idle timeout (default 10) after which worker threads are
		1913	allowed to exit. SEe C<IO::AIO::max_idle>.
		1914
1359	=item IO::AIO::max_outstanding $maxreqs	1915	=item IO::AIO::max_outstanding $maxreqs
		1916
		1917	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1918	you do queue up more than this number of requests, the next call to
		1919	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1920	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1921	longer exceeded.
		1922
		1923	In other words, this setting does not enforce a queue limit, but can be
		1924	used to make poll functions block if the limit is exceeded.
1360		1925
1361	This is a very bad function to use in interactive programs because it	1926	This is a very bad function to use in interactive programs because it
1362	blocks, and a bad way to reduce concurrency because it is inexact: Better	1927	blocks, and a bad way to reduce concurrency because it is inexact: Better
1363	use an C<aio_group> together with a feed callback.	1928	use an C<aio_group> together with a feed callback.
1364		1929
1365	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1930	It's main use is in scripts without an event loop - when you want to stat
1366	do queue up more than this number of requests, the next call to the	1931	a lot of files, you can write somehting like this:
1367	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1368	function will block until the limit is no longer exceeded.
1369		1932
1370	The default value is very large, so there is no practical limit on the	1933	IO::AIO::max_outstanding 32;
1371	number of outstanding requests.
1372		1934
1373	You can still queue as many requests as you want. Therefore,	1935	for my $path (...) {
1374	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1936	aio_stat $path , ...;
1375	as a stop gap to shield against fatal memory overflow (with large values).	1937	IO::AIO::poll_cb;
		1938	}
		1939
		1940	IO::AIO::flush;
		1941
		1942	The call to C<poll_cb> inside the loop will normally return instantly, but
		1943	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1944	some requests have been handled. This keeps the loop from pushing a large
		1945	number of C<aio_stat> requests onto the queue.
		1946
		1947	The default value for C<max_outstanding> is very large, so there is no
		1948	practical limit on the number of outstanding requests.
1376		1949
1377	=back	1950	=back
1378		1951
1379	=head3 STATISTICAL INFORMATION	1952	=head3 STATISTICAL INFORMATION
1380		1953
…		…
1418		1991
1419	Returns the number of bytes copied, or C<-1> on error.	1992	Returns the number of bytes copied, or C<-1> on error.
1420		1993
1421	=item IO::AIO::fadvise $fh, $offset, $len, $advice	1994	=item IO::AIO::fadvise $fh, $offset, $len, $advice
1422		1995
1423	Simply calls the C<posix_fadvise> function (see it's	1996	Simply calls the C<posix_fadvise> function (see its
1424	manpage for details). The following advice constants are	1997	manpage for details). The following advice constants are
1425	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,	1998	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
1426	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,	1999	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
1427	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.	2000	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
1428		2001
1429	On systems that do not implement C<posix_fadvise>, this function returns	2002	On systems that do not implement C<posix_fadvise>, this function returns
1430	ENOSYS, otherwise the return value of C<posix_fadvise>.	2003	ENOSYS, otherwise the return value of C<posix_fadvise>.
1431		2004
		2005	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		2006
		2007	Simply calls the C<posix_madvise> function (see its
		2008	manpage for details). The following advice constants are
		2009	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		2010	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		2011
		2012	On systems that do not implement C<posix_madvise>, this function returns
		2013	ENOSYS, otherwise the return value of C<posix_madvise>.
		2014
		2015	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		2016
		2017	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		2018	$scalar (see its manpage for details). The following protect
		2019	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		2020	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2021
		2022	On systems that do not implement C<mprotect>, this function returns
		2023	ENOSYS, otherwise the return value of C<mprotect>.
		2024
		2025	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		2026
		2027	Memory-maps a file (or anonymous memory range) and attaches it to the
		2028	given C<$scalar>, which will act like a string scalar. Returns true on
		2029	success, and false otherwise.
		2030
		2031	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		2032	change the string length, and most read-only operations such as copying it
		2033	or searching it with regexes and so on.
		2034
		2035	Anything else is unsafe and will, at best, result in memory leaks.
		2036
		2037	The memory map associated with the C<$scalar> is automatically removed
		2038	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		2039	C<IO::AIO::munmap> functions are called.
		2040
		2041	This calls the C<mmap>(2) function internally. See your system's manual
		2042	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		2043
		2044	The C<$length> must be larger than zero and smaller than the actual
		2045	filesize.
		2046
		2047	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		2048	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		2049
		2050	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		2051	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		2052	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		2053	(which is set to C<MAP_ANON> if your system only provides this
		2054	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		2055	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		2056	C<IO::AIO::MAP_NONBLOCK>
		2057
		2058	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		2059
		2060	C<$offset> is the offset from the start of the file - it generally must be
		2061	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		2062
		2063	Example:
		2064
		2065	use Digest::MD5;
		2066	use IO::AIO;
		2067
		2068	open my $fh, "<verybigfile"
		2069	or die "$!";
		2070
		2071	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		2072	or die "verybigfile: $!";
		2073
		2074	my $fast_md5 = md5 $data;
		2075
		2076	=item IO::AIO::munmap $scalar
		2077
		2078	Removes a previous mmap and undefines the C<$scalar>.
		2079
		2080	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		2081
		2082	Calls the C<munlock> function, undoing the effects of a previous
		2083	C<aio_mlock> call (see its description for details).
		2084
		2085	=item IO::AIO::munlockall
		2086
		2087	Calls the C<munlockall> function.
		2088
		2089	On systems that do not implement C<munlockall>, this function returns
		2090	ENOSYS, otherwise the return value of C<munlockall>.
		2091
		2092	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2093
		2094	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2095	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2096	should be the file offset.
		2097
		2098	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2099	silently corrupt the data in this case.
		2100
		2101	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2102	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2103	C<IO::AIO::SPLICE_F_GIFT>.
		2104
		2105	See the C<splice(2)> manpage for details.
		2106
		2107	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2108
		2109	Calls the GNU/Linux C<tee(2)> syscall, see it's manpage and the
		2110	description for C<IO::AIO::splice> above for details.
		2111
1432	=back	2112	=back
1433		2113
1434	=cut	2114	=cut
1435		2115
1436	min_parallel 8;	2116	min_parallel 8;
1437		2117
1438	END { flush }	2118	END { flush }
1439		2119
1440	1;	2120	1;
1441		2121
		2122	=head1 EVENT LOOP INTEGRATION
		2123
		2124	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		2125	automatically into many event loops:
		2126
		2127	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		2128	use AnyEvent::AIO;
		2129
		2130	You can also integrate IO::AIO manually into many event loops, here are
		2131	some examples of how to do this:
		2132
		2133	# EV integration
		2134	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		2135
		2136	# Event integration
		2137	Event->io (fd => IO::AIO::poll_fileno,
		2138	poll => 'r',
		2139	cb => \&IO::AIO::poll_cb);
		2140
		2141	# Glib/Gtk2 integration
		2142	add_watch Glib::IO IO::AIO::poll_fileno,
		2143	in => sub { IO::AIO::poll_cb; 1 };
		2144
		2145	# Tk integration
		2146	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		2147	readable => \&IO::AIO::poll_cb);
		2148
		2149	# Danga::Socket integration
		2150	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		2151	\&IO::AIO::poll_cb);
		2152
1442	=head2 FORK BEHAVIOUR	2153	=head2 FORK BEHAVIOUR
1443		2154
1444	This module should do "the right thing" when the process using it forks:	2155	Usage of pthreads in a program changes the semantics of fork
		2156	considerably. Specifically, only async-safe functions can be called after
		2157	fork. Perl doesn't know about this, so in general, you cannot call fork
		2158	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2159	pthreads, so this applies, but many other extensions and (for inexplicable
		2160	reasons) perl itself often is linked against pthreads, so this limitation
		2161	applies to quite a lot of perls.
1445		2162
1446	Before the fork, IO::AIO enters a quiescent state where no requests	2163	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1447	can be added in other threads and no results will be processed. After	2164	only works in the process that loaded it. Forking is fully supported, but
1448	the fork the parent simply leaves the quiescent state and continues	2165	using IO::AIO in the child is not.
1449	request/result processing, while the child frees the request/result queue
1450	(so that the requests started before the fork will only be handled in the
1451	parent). Threads will be started on demand until the limit set in the
1452	parent process has been reached again.
1453		2166
1454	In short: the parent will, after a short pause, continue as if fork had	2167	You might get around by not I<using> IO::AIO before (or after)
1455	not been called, while the child will act as if IO::AIO has not been used	2168	forking. You could also try to call the L<IO::AIO::reinit> function in the
1456	yet.	2169	child:
		2170
		2171	=over 4
		2172
		2173	=item IO::AIO::reinit
		2174
		2175	Abandons all current requests and I/O threads and simply reinitialises all
		2176	data structures. This is not an operation supported by any standards, but
		2177	happens to work on GNU/Linux and some newer BSD systems.
		2178
		2179	The only reasonable use for this function is to call it after forking, if
		2180	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2181	the process will result in undefined behaviour. Calling it at any time
		2182	will also result in any undefined (by POSIX) behaviour.
		2183
		2184	=back
1457		2185
1458	=head2 MEMORY USAGE	2186	=head2 MEMORY USAGE
1459		2187
1460	Per-request usage:	2188	Per-request usage:
1461		2189

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