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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.156 by root, Tue Jun 16 23:41:59 2009 UTC vs.
Revision 1.238 by root, Thu Oct 11 05:01:56 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;
…		…
186		163
187	package IO::AIO;	164	package IO::AIO;
188		165
189	use Carp ();	166	use Carp ();
190		167
191	no warnings;	168	use common::sense;
192	use strict 'vars';
193		169
194	use base 'Exporter';	170	use base 'Exporter';
195		171
196	BEGIN {	172	BEGIN {
197	our $VERSION = '3.23';	173	our $VERSION = '4.18';
198		174
199	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
200	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
201	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
202	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
203	aio_rename aio_link aio_move aio_copy aio_group	180	aio_rename aio_link aio_move aio_copy aio_group
204	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
205	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);
206		186
207	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	187	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
208	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	188	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
209	min_parallel max_parallel max_idle	189	min_parallel max_parallel max_idle idle_timeout
210	nreqs nready npending nthreads	190	nreqs nready npending nthreads
211	max_poll_time max_poll_reqs);	191	max_poll_time max_poll_reqs
		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
…		…
634		917
635	=item aio_copy $srcpath, $dstpath, $callback->($status)	918	=item aio_copy $srcpath, $dstpath, $callback->($status)
636		919
637	Try to copy the I<file> (directories not supported as either source or	920	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	921	destination) from C<$srcpath> to C<$dstpath> and call the callback with
639	the C<0> (error) or C<-1> ok.	922	a status of C<0> (ok) or C<-1> (error, see C<$!>).
640		923
641	This is a composite request that creates the destination file with	924	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	925	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	926	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
644	uid/gid, in that order.	927	uid/gid, in that order.
…		…
656	my $grp = aio_group $cb;	939	my $grp = aio_group $cb;
657		940
658	aioreq_pri $pri;	941	aioreq_pri $pri;
659	add $grp aio_open $src, O_RDONLY, 0, sub {	942	add $grp aio_open $src, O_RDONLY, 0, sub {
660	if (my $src_fh = $_[0]) {	943	if (my $src_fh = $_[0]) {
661	my @stat = stat $src_fh; # hmm, might bock over nfs?	944	my @stat = stat $src_fh; # hmm, might block over nfs?
662		945
663	aioreq_pri $pri;	946	aioreq_pri $pri;
664	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	947	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
665	if (my $dst_fh = $_[0]) {	948	if (my $dst_fh = $_[0]) {
666	aioreq_pri $pri;	949	aioreq_pri $pri;
…		…
713		996
714	=item aio_move $srcpath, $dstpath, $callback->($status)	997	=item aio_move $srcpath, $dstpath, $callback->($status)
715		998
716	Try to move the I<file> (directories not supported as either source or	999	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	1000	destination) from C<$srcpath> to C<$dstpath> and call the callback with
718	the C<0> (error) or C<-1> ok.	1001	a status of C<0> (ok) or C<-1> (error, see C<$!>).
719		1002
720	This is a composite request that tries to rename(2) the file first; if	1003	This is a composite request that tries to rename(2) the file first; if
721	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if	1004	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
722	that is successful, unlinks the C<$srcpath>.	1005	that is successful, unlinks the C<$srcpath>.
723		1006
…		…
734	if ($_[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.
…		…
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
959	written to disc. It works for anything that can be opened for read-only,	1260	written to disc. It works for anything that can be opened for read-only,
960	not just directories.	1261	not just directories.
		1262
		1263	Future versions of this function might fall back to other methods when
		1264	C<fsync> on the directory fails (such as calling C<sync>).
961		1265
962	Passes C<0> when everything went ok, and C<-1> on error.	1266	Passes C<0> when everything went ok, and C<-1> on error.
963		1267
964	=cut	1268	=cut
965		1269
…		…
986	};	1290	};
987		1291
988	$grp	1292	$grp
989	}	1293	}
990		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 page s(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
991	=item aio_group $callback->(...)	1406	=item aio_group $callback->(...)
992		1407
993	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
994	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
995	many requests into a single, composite, request with a definite callback	1410	many requests into a single, composite, request with a definite callback
…		…
1031	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
1032	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
1033	except to put your application under artificial I/O pressure.	1448	except to put your application under artificial I/O pressure.
1034		1449
1035	=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 fucntionality 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
		1562	if the pathname would be specified directly, without a directory object,
		1563	e.g., these calls are functionally identical:
		1564
		1565	aio_stat "somefile", sub { ... };
		1566	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1567
		1568	=back
		1569
1036		1570
1037	=head2 IO::AIO::REQ CLASS	1571	=head2 IO::AIO::REQ CLASS
1038		1572
1039	All non-aggregate C<aio_*> functions return an object of this class when	1573	All non-aggregate C<aio_*> functions return an object of this class when
1040	called in non-void context.	1574	called in non-void context.
…		…
1130	=item $grp->cancel_subs	1664	=item $grp->cancel_subs
1131		1665
1132	Cancel all subrequests and clears any feeder, but not the group request	1666	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.	1667	itself. Useful when you queued a lot of events but got a result early.
1134		1668
		1669	The group request will finish normally (you cannot add requests to the
		1670	group).
		1671
1135	=item $grp->result (...)	1672	=item $grp->result (...)
1136		1673
1137	Set the result value(s) that will be passed to the group callback when all	1674	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	1675	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,	1676	of errno (just like calling C<errno> without an error number). By default,
…		…
1155		1692
1156	Sets a feeder/generator on this group: every group can have an attached	1693	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,	1694	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,	1695	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,	1696	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,	1697	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1161	delaying any later requests for a long time.	1698	requests, delaying any later requests for a long time.
1162		1699
1163	To avoid this, and allow incremental generation of requests, you can	1700	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	1701	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>,	1702	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	1703	below) requests active in the group itself and is expected to queue more
…		…
1215		1752
1216	See C<poll_cb> for an example.	1753	See C<poll_cb> for an example.
1217		1754
1218	=item IO::AIO::poll_cb	1755	=item IO::AIO::poll_cb
1219		1756
1220	Process some outstanding events on the result pipe. You have to call this	1757	Process some outstanding events on the result pipe. You have to call
1221	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1758	this regularly. Returns C<0> if all events could be processed (or there
1222	returned earlier for whatever reason. Returns immediately when no events	1759	were no events to process), or C<-1> if it returned earlier for whatever
1223	are outstanding. The amount of events processed depends on the settings of	1760	reason. Returns immediately when no events are outstanding. The amount of
1224	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.	1761	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1762	C<IO::AIO::max_poll_time>.
1225		1763
1226	If not all requests were processed for whatever reason, the filehandle	1764	If not all requests were processed for whatever reason, the filehandle
1227	will still be ready when C<poll_cb> returns, so normally you don't have to	1765	will still be ready when C<poll_cb> returns, so normally you don't have to
1228	do anything special to have it called later.	1766	do anything special to have it called later.
1229		1767
		1768	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1769	ready, it can be beneficial to call this function from loops which submit
		1770	a lot of requests, to make sure the results get processed when they become
		1771	available and not just when the loop is finished and the event loop takes
		1772	over again. This function returns very fast when there are no outstanding
		1773	requests.
		1774
1230	Example: Install an Event watcher that automatically calls	1775	Example: Install an Event watcher that automatically calls
1231	IO::AIO::poll_cb with high priority (more examples can be found in the	1776	IO::AIO::poll_cb with high priority (more examples can be found in the
1232	SYNOPSIS section, at the top of this document):	1777	SYNOPSIS section, at the top of this document):
1233		1778
1234	Event->io (fd => IO::AIO::poll_fileno,	1779	Event->io (fd => IO::AIO::poll_fileno,
1235	poll => 'r', async => 1,	1780	poll => 'r', async => 1,
1236	cb => \&IO::AIO::poll_cb);	1781	cb => \&IO::AIO::poll_cb);
		1782
		1783	=item IO::AIO::poll_wait
		1784
		1785	If there are any outstanding requests and none of them in the result
		1786	phase, wait till the result filehandle becomes ready for reading (simply
		1787	does a C<select> on the filehandle. This is useful if you want to
		1788	synchronously wait for some requests to finish).
		1789
		1790	See C<nreqs> for an example.
		1791
		1792	=item IO::AIO::poll
		1793
		1794	Waits until some requests have been handled.
		1795
		1796	Returns the number of requests processed, but is otherwise strictly
		1797	equivalent to:
		1798
		1799	IO::AIO::poll_wait, IO::AIO::poll_cb
		1800
		1801	=item IO::AIO::flush
		1802
		1803	Wait till all outstanding AIO requests have been handled.
		1804
		1805	Strictly equivalent to:
		1806
		1807	IO::AIO::poll_wait, IO::AIO::poll_cb
		1808	while IO::AIO::nreqs;
1237		1809
1238	=item IO::AIO::max_poll_reqs $nreqs	1810	=item IO::AIO::max_poll_reqs $nreqs
1239		1811
1240	=item IO::AIO::max_poll_time $seconds	1812	=item IO::AIO::max_poll_time $seconds
1241		1813
…		…
1266	# use a low priority so other tasks have priority	1838	# use a low priority so other tasks have priority
1267	Event->io (fd => IO::AIO::poll_fileno,	1839	Event->io (fd => IO::AIO::poll_fileno,
1268	poll => 'r', nice => 1,	1840	poll => 'r', nice => 1,
1269	cb => &IO::AIO::poll_cb);	1841	cb => &IO::AIO::poll_cb);
1270		1842
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	1843	=back
1299		1844
1300	=head3 CONTROLLING THE NUMBER OF THREADS	1845	=head3 CONTROLLING THE NUMBER OF THREADS
1301		1846
1302	=over	1847	=over
…		…
1335		1880
1336	Under normal circumstances you don't need to call this function.	1881	Under normal circumstances you don't need to call this function.
1337		1882
1338	=item IO::AIO::max_idle $nthreads	1883	=item IO::AIO::max_idle $nthreads
1339		1884
1340	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1885	Limit the number of threads (default: 4) that are allowed to idle
1341	threads that did not get a request to process within 10 seconds). That	1886	(i.e., threads that did not get a request to process within the idle
1342	means if a thread becomes idle while C<$nthreads> other threads are also	1887	timeout (default: 10 seconds). That means if a thread becomes idle while
1343	idle, it will free its resources and exit.	1888	C<$nthreads> other threads are also idle, it will free its resources and
		1889	exit.
1344		1890
1345	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1891	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	1892	to allow for extremely high load situations, but want to free resources
1347	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1893	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1348		1894
1349	The default is probably ok in most situations, especially if thread	1895	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	1896	creation is fast. If thread creation is very slow on your system you might
1351	want to use larger values.	1897	want to use larger values.
1352		1898
		1899	=item IO::AIO::idle_timeout $seconds
		1900
		1901	Sets the minimum idle timeout (default 10) after which worker threads are
		1902	allowed to exit. SEe C<IO::AIO::max_idle>.
		1903
1353	=item IO::AIO::max_outstanding $maxreqs	1904	=item IO::AIO::max_outstanding $maxreqs
		1905
		1906	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1907	you do queue up more than this number of requests, the next call to
		1908	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1909	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1910	longer exceeded.
		1911
		1912	In other words, this setting does not enforce a queue limit, but can be
		1913	used to make poll functions block if the limit is exceeded.
1354		1914
1355	This is a very bad function to use in interactive programs because it	1915	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	1916	blocks, and a bad way to reduce concurrency because it is inexact: Better
1357	use an C<aio_group> together with a feed callback.	1917	use an C<aio_group> together with a feed callback.
1358		1918
1359	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1919	It's 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	1920	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		1921
1364	The default value is very large, so there is no practical limit on the	1922	IO::AIO::max_outstanding 32;
1365	number of outstanding requests.
1366		1923
1367	You can still queue as many requests as you want. Therefore,	1924	for my $path (...) {
1368	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1925	aio_stat $path , ...;
1369	as a stop gap to shield against fatal memory overflow (with large values).	1926	IO::AIO::poll_cb;
		1927	}
		1928
		1929	IO::AIO::flush;
		1930
		1931	The call to C<poll_cb> inside the loop will normally return instantly, but
		1932	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1933	some requests have been handled. This keeps the loop from pushing a large
		1934	number of C<aio_stat> requests onto the queue.
		1935
		1936	The default value for C<max_outstanding> is very large, so there is no
		1937	practical limit on the number of outstanding requests.
1370		1938
1371	=back	1939	=back
1372		1940
1373	=head3 STATISTICAL INFORMATION	1941	=head3 STATISTICAL INFORMATION
1374		1942
…		…
1394	Returns the number of requests currently in the pending state (executed,	1962	Returns the number of requests currently in the pending state (executed,
1395	but not yet processed by poll_cb).	1963	but not yet processed by poll_cb).
1396		1964
1397	=back	1965	=back
1398		1966
		1967	=head3 MISCELLANEOUS FUNCTIONS
		1968
		1969	IO::AIO implements some functions that might be useful, but are not
		1970	asynchronous.
		1971
		1972	=over 4
		1973
		1974	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1975
		1976	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1977	but is blocking (this makes most sense if you know the input data is
		1978	likely cached already and the output filehandle is set to non-blocking
		1979	operations).
		1980
		1981	Returns the number of bytes copied, or C<-1> on error.
		1982
		1983	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1984
		1985	Simply calls the C<posix_fadvise> function (see its
		1986	manpage for details). The following advice constants are
		1987	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1988	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1989	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1990
		1991	On systems that do not implement C<posix_fadvise>, this function returns
		1992	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1993
		1994	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1995
		1996	Simply calls the C<posix_madvise> function (see its
		1997	manpage for details). The following advice constants are
		1998	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1999	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		2000
		2001	On systems that do not implement C<posix_madvise>, this function returns
		2002	ENOSYS, otherwise the return value of C<posix_madvise>.
		2003
		2004	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		2005
		2006	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		2007	$scalar (see its manpage for details). The following protect
		2008	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		2009	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2010
		2011	On systems that do not implement C<mprotect>, this function returns
		2012	ENOSYS, otherwise the return value of C<mprotect>.
		2013
		2014	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		2015
		2016	Memory-maps a file (or anonymous memory range) and attaches it to the
		2017	given C<$scalar>, which will act like a string scalar. Returns true on
		2018	success, and false otherwise.
		2019
		2020	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		2021	change the string length, and most read-only operations such as copying it
		2022	or searching it with regexes and so on.
		2023
		2024	Anything else is unsafe and will, at best, result in memory leaks.
		2025
		2026	The memory map associated with the C<$scalar> is automatically removed
		2027	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		2028	C<IO::AIO::munmap> functions are called.
		2029
		2030	This calls the C<mmap>(2) function internally. See your system's manual
		2031	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		2032
		2033	The C<$length> must be larger than zero and smaller than the actual
		2034	filesize.
		2035
		2036	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		2037	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		2038
		2039	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		2040	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		2041	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		2042	(which is set to C<MAP_ANON> if your system only provides this
		2043	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		2044	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		2045	C<IO::AIO::MAP_NONBLOCK>
		2046
		2047	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		2048
		2049	C<$offset> is the offset from the start of the file - it generally must be
		2050	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		2051
		2052	Example:
		2053
		2054	use Digest::MD5;
		2055	use IO::AIO;
		2056
		2057	open my $fh, "<verybigfile"
		2058	or die "$!";
		2059
		2060	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		2061	or die "verybigfile: $!";
		2062
		2063	my $fast_md5 = md5 $data;
		2064
		2065	=item IO::AIO::munmap $scalar
		2066
		2067	Removes a previous mmap and undefines the C<$scalar>.
		2068
		2069	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		2070
		2071	Calls the C<munlock> function, undoing the effects of a previous
		2072	C<aio_mlock> call (see its description for details).
		2073
		2074	=item IO::AIO::munlockall
		2075
		2076	Calls the C<munlockall> function.
		2077
		2078	On systems that do not implement C<munlockall>, this function returns
		2079	ENOSYS, otherwise the return value of C<munlockall>.
		2080
		2081	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2082
		2083	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2084	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2085	should be the file offset.
		2086
		2087	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2088	silently corrupt the data in this case.
		2089
		2090	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2091	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2092	C<IO::AIO::SPLICE_F_GIFT>.
		2093
		2094	See the C<splice(2)> manpage for details.
		2095
		2096	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2097
		2098	Calls the GNU/Linux C<tee(2)> syscall, see it's manpage and the
		2099	description for C<IO::AIO::splice> above for details.
		2100
		2101	=back
		2102
1399	=cut	2103	=cut
1400		2104
1401	min_parallel 8;	2105	min_parallel 8;
1402		2106
1403	END { flush }	2107	END { flush }
1404		2108
1405	1;	2109	1;
1406		2110
		2111	=head1 EVENT LOOP INTEGRATION
		2112
		2113	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		2114	automatically into many event loops:
		2115
		2116	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		2117	use AnyEvent::AIO;
		2118
		2119	You can also integrate IO::AIO manually into many event loops, here are
		2120	some examples of how to do this:
		2121
		2122	# EV integration
		2123	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		2124
		2125	# Event integration
		2126	Event->io (fd => IO::AIO::poll_fileno,
		2127	poll => 'r',
		2128	cb => \&IO::AIO::poll_cb);
		2129
		2130	# Glib/Gtk2 integration
		2131	add_watch Glib::IO IO::AIO::poll_fileno,
		2132	in => sub { IO::AIO::poll_cb; 1 };
		2133
		2134	# Tk integration
		2135	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		2136	readable => \&IO::AIO::poll_cb);
		2137
		2138	# Danga::Socket integration
		2139	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		2140	\&IO::AIO::poll_cb);
		2141
1407	=head2 FORK BEHAVIOUR	2142	=head2 FORK BEHAVIOUR
1408		2143
1409	This module should do "the right thing" when the process using it forks:	2144	Usage of pthreads in a program changes the semantics of fork
		2145	considerably. Specifically, only async-safe functions can be called after
		2146	fork. Perl doesn't know about this, so in general, you cannot call fork
		2147	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2148	pthreads, so this applies, but many other extensions and (for inexplicable
		2149	reasons) perl itself often is linked against pthreads, so this limitation
		2150	applies to quite a lot of perls.
1410		2151
1411	Before the fork, IO::AIO enters a quiescent state where no requests	2152	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	2153	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	2154	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		2155
1419	In short: the parent will, after a short pause, continue as if fork had	2156	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	2157	forking. You could also try to call the L<IO::AIO::reinit> function in the
1421	yet.	2158	child:
		2159
		2160	=over 4
		2161
		2162	=item IO::AIO::reinit
		2163
		2164	Abandons all current requests and I/O threads and simply reinitialises all
		2165	data structures. This is not an operation supported by any standards, but
		2166	happens to work on GNU/Linux and some newer BSD systems.
		2167
		2168	The only reasonable use for this function is to call it after forking, if
		2169	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2170	the process will result in undefined behaviour. Calling it at any time
		2171	will also result in any undefined (by POSIX) behaviour.
		2172
		2173	=back
1422		2174
1423	=head2 MEMORY USAGE	2175	=head2 MEMORY USAGE
1424		2176
1425	Per-request usage:	2177	Per-request usage:
1426		2178

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