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Revision 1.99 by root, Sun Jan 7 21:32:20 2007 UTC vs.
Revision 1.220 by root, Sun Apr 1 17:46:02 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
…		…
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		30
31	# AnyEvent integration
32	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
33	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
34
35	# Event integration
36	Event->io (fd => IO::AIO::poll_fileno,
37	poll => 'r',
38	cb => \&IO::AIO::poll_cb);
39
40	# Glib/Gtk2 integration
41	add_watch Glib::IO IO::AIO::poll_fileno,
42	in => sub { IO::AIO::poll_cb; 1 };
43
44	# Tk integration
45	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
46	readable => \&IO::AIO::poll_cb);
47
48	# Danga::Socket integration
49	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
50	\&IO::AIO::poll_cb);
51
52	=head1 DESCRIPTION	31	=head1 DESCRIPTION
53		32
54	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
55	operating system supports.	34	operating system supports. It is implemented as an interface to C<libeio>
		35	(L<http://software.schmorp.de/pkg/libeio.html>).
56		36
57	Asynchronous means that operations that can normally block your program	37	Asynchronous means that operations that can normally block your program
58	(e.g. reading from disk) will be done asynchronously: the operation	38	(e.g. reading from disk) will be done asynchronously: the operation
59	will still block, but you can do something else in the meantime. This	39	will still block, but you can do something else in the meantime. This
60	is extremely useful for programs that need to stay interactive even	40	is extremely useful for programs that need to stay interactive even
…		…
62	etc.), but can also be used to easily do operations in parallel that are	42	etc.), but can also be used to easily do operations in parallel that are
63	normally done sequentially, e.g. stat'ing many files, which is much faster	43	normally done sequentially, e.g. stat'ing many files, which is much faster
64	on a RAID volume or over NFS when you do a number of stat operations	44	on a RAID volume or over NFS when you do a number of stat operations
65	concurrently.	45	concurrently.
66		46
67	While most of this works on all types of file descriptors (for example	47	While most of this works on all types of file descriptors (for
68	sockets), using these functions on file descriptors that support	48	example sockets), using these functions on file descriptors that
69	nonblocking operation (again, sockets, pipes etc.) is very inefficient or	49	support nonblocking operation (again, sockets, pipes etc.) is
70	might not work (aio_read fails on sockets/pipes/fifos). Use an event loop	50	very inefficient. Use an event loop for that (such as the L<EV>
71	for that (such as the L<Event|Event> module): IO::AIO will naturally fit	51	module): IO::AIO will naturally fit into such an event loop itself.
72	into such an event loop itself.
73		52
74	In this version, a number of threads are started that execute your	53	In this version, a number of threads are started that execute your
75	requests and signal their completion. You don't need thread support	54	requests and signal their completion. You don't need thread support
76	in perl, and the threads created by this module will not be visible	55	in perl, and the threads created by this module will not be visible
77	to perl. In the future, this module might make use of the native aio	56	to perl. In the future, this module might make use of the native aio
…		…
79	not well-supported or restricted (GNU/Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
80	files currently, for example), and they would only support aio_read and	59	files currently, for example), and they would only support aio_read and
81	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
82	using threads anyway.	61	using threads anyway.
83		62
84	Although the module will work with in the presence of other (Perl-)	63	Although the module will work in the presence of other (Perl-) threads,
85	threads, it is currently not reentrant in any way, so use appropriate	64	it is currently not reentrant in any way, so use appropriate locking
86	locking yourself, always call C<poll_cb> from within the same thread, or	65	yourself, always call C<poll_cb> from within the same thread, or never
87	never call C<poll_cb> (or other C<aio_> functions) recursively.	66	call C<poll_cb> (or other C<aio_> functions) recursively.
88		67
89	=head2 EXAMPLE	68	=head2 EXAMPLE
90		69
91	This is a simple example that uses the Event module and loads	70	This is a simple example that uses the EV module and loads
92	F</etc/passwd> asynchronously:	71	F</etc/passwd> asynchronously:
93		72
94	use Fcntl;	73	use Fcntl;
95	use Event;	74	use EV;
96	use IO::AIO;	75	use IO::AIO;
97		76
98	# register the IO::AIO callback with Event	77	# register the IO::AIO callback with EV
99	Event->io (fd => IO::AIO::poll_fileno,	78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
100	poll => 'r',
101	cb => \&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;
…		…
118		95
119	# file contents now in $contents	96	# file contents now in $contents
120	print $contents;	97	print $contents;
121		98
122	# exit event loop and program	99	# exit event loop and program
123	Event::unloop;	100	EV::unloop;
124	};	101	};
125	};	102	};
126		103
127	# possibly queue up other requests, or open GUI windows,	104	# possibly queue up other requests, or open GUI windows,
128	# check for sockets etc. etc.	105	# check for sockets etc. etc.
129		106
130	# process events as long as there are some:	107	# process events as long as there are some:
131	Event::loop;	108	EV::loop;
132		109
133	=head1 REQUEST ANATOMY AND LIFETIME	110	=head1 REQUEST ANATOMY AND LIFETIME
134		111
135	Every C<aio_*> function creates a request. which is a C data structure not	112	Every C<aio_*> function creates a request. which is a C data structure not
136	directly visible to Perl.	113	directly visible to Perl.
…		…
184		161
185	=cut	162	=cut
186		163
187	package IO::AIO;	164	package IO::AIO;
188		165
189	no warnings;	166	use Carp ();
190	use strict 'vars';	167
		168	use common::sense;
191		169
192	use base 'Exporter';	170	use base 'Exporter';
193		171
194	BEGIN {	172	BEGIN {
195	our $VERSION = '2.32';	173	our $VERSION = '4.13';
196		174
197	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	175	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
198	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
199	aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link	177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
200	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree);	178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate
		179	aio_pathsync aio_readahead
		180	aio_rename aio_link aio_move aio_copy aio_group
		181	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		182	aio_chmod aio_utime aio_truncate
		183	aio_msync aio_mtouch aio_mlock aio_mlockall
		184	aio_statvfs
		185	aio_wd);
		186
201	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));	187	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
202	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	188	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
203	min_parallel max_parallel max_idle	189	min_parallel max_parallel max_idle idle_timeout
204	nreqs nready npending nthreads	190	nreqs nready npending nthreads
205	max_poll_time max_poll_reqs);	191	max_poll_time max_poll_reqs
		192	sendfile fadvise madvise
		193	mmap munmap munlock munlockall);
		194
		195	push @AIO_REQ, qw(aio_busy); # not exported
206		196
207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	197	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
208		198
209	require XSLoader;	199	require XSLoader;
210	XSLoader::load ("IO::AIO", $VERSION);	200	XSLoader::load ("IO::AIO", $VERSION);
211	}	201	}
212		202
213	=head1 FUNCTIONS	203	=head1 FUNCTIONS
214		204
215	=head2 AIO REQUEST FUNCTIONS	205	=head2 QUICK OVERVIEW
		206
		207	This section simply lists the prototypes of the most important functions
		208	for 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_unlink $pathname, $callback->($status)
		227	aio_mknod $pathname, $mode, $dev, $callback->($status)
		228	aio_link $srcpath, $dstpath, $callback->($status)
		229	aio_symlink $srcpath, $dstpath, $callback->($status)
		230	aio_readlink $pathname, $callback->($link)
		231	aio_realpath $pathname, $callback->($link)
		232	aio_rename $srcpath, $dstpath, $callback->($status)
		233	aio_mkdir $pathname, $mode, $callback->($status)
		234	aio_rmdir $pathname, $callback->($status)
		235	aio_readdir $pathname, $callback->($entries)
		236	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		237	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		238	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		239	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		240	aio_load $pathname, $data, $callback->($status)
		241	aio_copy $srcpath, $dstpath, $callback->($status)
		242	aio_move $srcpath, $dstpath, $callback->($status)
		243	aio_rmtree $pathname, $callback->($status)
		244	aio_sync $callback->($status)
		245	aio_syncfs $fh, $callback->($status)
		246	aio_fsync $fh, $callback->($status)
		247	aio_fdatasync $fh, $callback->($status)
		248	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		249	aio_pathsync $pathname, $callback->($status)
		250	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		251	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		252	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		253	aio_mlockall $flags, $callback->($status)
		254	aio_group $callback->(...)
		255	aio_nop $callback->()
		256
		257	$prev_pri = aioreq_pri [$pri]
		258	aioreq_nice $pri_adjust
		259
		260	IO::AIO::poll_wait
		261	IO::AIO::poll_cb
		262	IO::AIO::poll
		263	IO::AIO::flush
		264	IO::AIO::max_poll_reqs $nreqs
		265	IO::AIO::max_poll_time $seconds
		266	IO::AIO::min_parallel $nthreads
		267	IO::AIO::max_parallel $nthreads
		268	IO::AIO::max_idle $nthreads
		269	IO::AIO::idle_timeout $seconds
		270	IO::AIO::max_outstanding $maxreqs
		271	IO::AIO::nreqs
		272	IO::AIO::nready
		273	IO::AIO::npending
		274
		275	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		276	IO::AIO::fadvise $fh, $offset, $len, $advice
		277	IO::AIO::madvise $scalar, $offset, $length, $advice
		278	IO::AIO::mprotect $scalar, $offset, $length, $protect
		279	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		280	IO::AIO::munlockall
		281
		282	=head2 API NOTES
216		283
217	All the C<aio_*> calls are more or less thin wrappers around the syscall	284	All the C<aio_*> calls are more or less thin wrappers around the syscall
218	with the same name (sans C<aio_>). The arguments are similar or identical,	285	with the same name (sans C<aio_>). The arguments are similar or identical,
219	and they all accept an additional (and optional) C<$callback> argument	286	and they all accept an additional (and optional) C<$callback> argument
220	which must be a code reference. This code reference will get called with	287	which must be a code reference. This code reference will be called after
221	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	288	the syscall has been executed in an asynchronous fashion. The results
222	perl, which usually delivers "false") as it's sole argument when the given	289	of the request will be passed as arguments to the callback (and, if an
223	syscall has been executed asynchronously.	290	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		291	most syscalls return C<-1> on error, unlike perl, which usually delivers
		292	"false").
		293
		294	Some requests (such as C<aio_readdir>) pass the actual results and
		295	communicate failures by passing C<undef>.
224		296
225	All functions expecting a filehandle keep a copy of the filehandle	297	All functions expecting a filehandle keep a copy of the filehandle
226	internally until the request has finished.	298	internally until the request has finished.
227		299
228	All functions return request objects of type L<IO::AIO::REQ> that allow	300	All functions return request objects of type L<IO::AIO::REQ> that allow
229	further manipulation of those requests while they are in-flight.	301	further manipulation of those requests while they are in-flight.
230		302
231	The pathnames you pass to these routines I<must> be absolute and	303	The pathnames you pass to these routines I<should> be absolute. The
232	encoded as octets. The reason for the former is that at the time the	304	reason for this is that at the time the request is being executed, the
233	request is being executed, the current working directory could have	305	current working directory could have changed. Alternatively, you can
234	changed. Alternatively, you can make sure that you never change the	306	make sure that you never change the current working directory anywhere
235	current working directory anywhere in the program and then use relative	307	in the program and then use relative paths. You can also take advantage
236	paths.	308	of IO::AIOs working directory abstraction, that lets you specify paths
		309	relative to some previously-opened "working directory object" - see the
		310	description of the C<IO::AIO::WD> class later in this document.
237		311
238	To encode pathnames as octets, either make sure you either: a) always pass	312	To encode pathnames as octets, either make sure you either: a) always pass
239	in filenames you got from outside (command line, readdir etc.) without	313	in filenames you got from outside (command line, readdir etc.) without
240	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	314	tinkering, b) are in your native filesystem encoding, c) use the Encode
241	your pathnames to the locale (or other) encoding in effect in the user	315	module and encode your pathnames to the locale (or other) encoding in
242	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	316	effect in the user environment, d) use Glib::filename_from_unicode on
243	use something else to ensure your scalar has the correct contents.	317	unicode filenames or e) use something else to ensure your scalar has the
		318	correct contents.
244		319
245	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	320	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
246	handles correctly wether it is set or not.	321	handles correctly whether it is set or not.
		322
		323	=head2 AIO REQUEST FUNCTIONS
247		324
248	=over 4	325	=over 4
249		326
250	=item $prev_pri = aioreq_pri [$pri]	327	=item $prev_pri = aioreq_pri [$pri]
251		328
…		…
271	aio_read $_[0], ..., sub {	348	aio_read $_[0], ..., sub {
272	...	349	...
273	};	350	};
274	};	351	};
275		352
		353
276	=item aioreq_nice $pri_adjust	354	=item aioreq_nice $pri_adjust
277		355
278	Similar to C<aioreq_pri>, but subtracts the given value from the current	356	Similar to C<aioreq_pri>, but subtracts the given value from the current
279	priority, so the effect is cumulative.	357	priority, so the effect is cumulative.
		358
280		359
281	=item aio_open $pathname, $flags, $mode, $callback->($fh)	360	=item aio_open $pathname, $flags, $mode, $callback->($fh)
282		361
283	Asynchronously open or create a file and call the callback with a newly	362	Asynchronously open or create a file and call the callback with a newly
284	created filehandle for the file.	363	created filehandle for the file.
…		…
290	list. They are the same as used by C<sysopen>.	369	list. They are the same as used by C<sysopen>.
291		370
292	Likewise, C<$mode> specifies the mode of the newly created file, if it	371	Likewise, C<$mode> specifies the mode of the newly created file, if it
293	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	372	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
294	except that it is mandatory (i.e. use C<0> if you don't create new files,	373	except that it is mandatory (i.e. use C<0> if you don't create new files,
295	and C<0666> or C<0777> if you do).	374	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		375	by the umask in effect then the request is being executed, so better never
		376	change the umask.
296		377
297	Example:	378	Example:
298		379
299	aio_open "/etc/passwd", O_RDONLY, 0, sub {	380	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
300	if ($_[0]) {	381	if ($_[0]) {
301	print "open successful, fh is $_[0]\n";	382	print "open successful, fh is $_[0]\n";
302	...	383	...
303	} else {	384	} else {
304	die "open failed: $!\n";	385	die "open failed: $!\n";
305	}	386	}
306	};	387	};
307		388
		389	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		390	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		391	following POSIX and non-POSIX constants are available (missing ones on
		392	your system are, as usual, C<0>):
		393
		394	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		395	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		396	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		397
		398
308	=item aio_close $fh, $callback->($status)	399	=item aio_close $fh, $callback->($status)
309		400
310	Asynchronously close a file and call the callback with the result	401	Asynchronously close a file and call the callback with the result
311	code. I<WARNING:> although accepted, you should not pass in a perl	402	code.
312	filehandle here, as perl will likely close the file descriptor another
313	time when the filehandle is destroyed. Normally, you can safely call perls
314	C<close> or just let filehandles go out of scope.
315		403
316	This is supposed to be a bug in the API, so that might change. It's	404	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
317	therefore best to avoid this function.	405	closing the file descriptor associated with the filehandle itself.
		406
		407	Therefore, C<aio_close> will not close the filehandle - instead it will
		408	use dup2 to overwrite the file descriptor with the write-end of a pipe
		409	(the pipe fd will be created on demand and will be cached).
		410
		411	Or in other words: the file descriptor will be closed, but it will not be
		412	free for reuse until the perl filehandle is closed.
		413
		414	=cut
		415
		416	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		417
		418	Seeks the filehandle to the new C<$offset>, similarly to perl'S
		419	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		420	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		421	C<IO::AIO::SEEK_END>).
		422
		423	The resulting absolute offset will be passed to the callback, or C<-1> in
		424	case of an error.
		425
		426	In theory, the C<$whence> constants could be different than the
		427	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		428	so don't panic.
318		429
319	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	430	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
320		431
321	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	432	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
322		433
323	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	434	Reads or writes C<$length> bytes from or to the specified C<$fh> and
324	into the scalar given by C<data> and offset C<dataoffset> and calls the	435	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
325	callback without the actual number of bytes read (or -1 on error, just	436	and calls the callback without the actual number of bytes read (or -1 on
326	like the syscall).	437	error, just like the syscall).
		438
		439	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		440	offset plus the actual number of bytes read.
		441
		442	If C<$offset> is undefined, then the current file descriptor offset will
		443	be used (and updated), otherwise the file descriptor offset will not be
		444	changed by these calls.
		445
		446	If C<$length> is undefined in C<aio_write>, use the remaining length of
		447	C<$data>.
		448
		449	If C<$dataoffset> is less than zero, it will be counted from the end of
		450	C<$data>.
327		451
328	The C<$data> scalar I<MUST NOT> be modified in any way while the request	452	The C<$data> scalar I<MUST NOT> be modified in any way while the request
329	is outstanding. Modifying it can result in segfaults or WW3 (if the	453	is outstanding. Modifying it can result in segfaults or World War III (if
330	necessary/optional hardware is installed).	454	the necessary/optional hardware is installed).
331		455
332	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	456	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
333	offset C<0> within the scalar:	457	offset C<0> within the scalar:
334		458
335	aio_read $fh, 7, 15, $buffer, 0, sub {	459	aio_read $fh, 7, 15, $buffer, 0, sub {
336	$_[0] > 0 or die "read error: $!";	460	$_[0] > 0 or die "read error: $!";
337	print "read $_[0] bytes: <$buffer>\n";	461	print "read $_[0] bytes: <$buffer>\n";
338	};	462	};
339		463
		464
340	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	465	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
341		466
342	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	467	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
343	reading at byte offset C<$in_offset>, and starts writing at the current	468	reading at byte offset C<$in_offset>, and starts writing at the current
344	file offset of C<$out_fh>. Because of that, it is not safe to issue more	469	file offset of C<$out_fh>. Because of that, it is not safe to issue more
345	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	470	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
346	other.	471	other. The same C<$in_fh> works fine though, as this function does not
		472	move or use the file offset of C<$in_fh>.
347		473
		474	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		475	are written, and there is no way to find out how many more bytes have been
		476	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		477	number of bytes written to C<$out_fh>. Only if the result value equals
		478	C<$length> one can assume that C<$length> bytes have been read.
		479
		480	Unlike with other C<aio_> functions, it makes a lot of sense to use
		481	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		482	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		483	the socket I/O will be non-blocking. Note, however, that you can run
		484	into a trap where C<aio_sendfile> reads some data with readahead, then
		485	fails to write all data, and when the socket is ready the next time, the
		486	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		487	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		488	resource usage.
		489
348	This call tries to make use of a native C<sendfile> syscall to provide	490	This call tries to make use of a native C<sendfile>-like syscall to
349	zero-copy operation. For this to work, C<$out_fh> should refer to a	491	provide zero-copy operation. For this to work, C<$out_fh> should refer to
350	socket, and C<$in_fh> should refer to mmap'able file.	492	a socket, and C<$in_fh> should refer to an mmap'able file.
351		493
352	If the native sendfile call fails or is not implemented, it will be	494	If a native sendfile cannot be found or it fails with C<ENOSYS>,
353	emulated, so you can call C<aio_sendfile> on any type of filehandle	495	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		496	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
354	regardless of the limitations of the operating system.	497	type of filehandle regardless of the limitations of the operating system.
355		498
356	Please note, however, that C<aio_sendfile> can read more bytes from	499	As native sendfile syscalls (as practically any non-POSIX interface hacked
357	C<$in_fh> than are written, and there is no way to find out how many	500	together in a hurry to improve benchmark numbers) tend to be rather buggy
358	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	501	on many systems, this implementation tries to work around some known bugs
359	provides the number of bytes written to C<$out_fh>. Only if the result	502	in Linux and FreeBSD kernels (probably others, too), but that might fail,
360	value equals C<$length> one can assume that C<$length> bytes have been	503	so you really really should check the return value of C<aio_sendfile> -
361	read.	504	fewre bytes than expected might have been transferred.
		505
362		506
363	=item aio_readahead $fh,$offset,$length, $callback->($retval)	507	=item aio_readahead $fh,$offset,$length, $callback->($retval)
364		508
365	C<aio_readahead> populates the page cache with data from a file so that	509	C<aio_readahead> populates the page cache with data from a file so that
366	subsequent reads from that file will not block on disk I/O. The C<$offset>	510	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
372	file. The current file offset of the file is left unchanged.	516	file. The current file offset of the file is left unchanged.
373		517
374	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	518	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
375	emulated by simply reading the data, which would have a similar effect.	519	emulated by simply reading the data, which would have a similar effect.
376		520
		521
377	=item aio_stat $fh_or_path, $callback->($status)	522	=item aio_stat $fh_or_path, $callback->($status)
378		523
379	=item aio_lstat $fh, $callback->($status)	524	=item aio_lstat $fh, $callback->($status)
380		525
381	Works like perl's C<stat> or C<lstat> in void context. The callback will	526	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
386	for an explanation.	531	for an explanation.
387		532
388	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	533	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
389	error when stat'ing a large file, the results will be silently truncated	534	error when stat'ing a large file, the results will be silently truncated
390	unless perl itself is compiled with large file support.	535	unless perl itself is compiled with large file support.
		536
		537	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		538	following constants and functions (if not implemented, the constants will
		539	be C<0> and the functions will either C<croak> or fall back on traditional
		540	behaviour).
		541
		542	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		543	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		544	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
391		545
392	Example: Print the length of F</etc/passwd>:	546	Example: Print the length of F</etc/passwd>:
393		547
394	aio_stat "/etc/passwd", sub {	548	aio_stat "/etc/passwd", sub {
395	$_[0] and die "stat failed: $!";	549	$_[0] and die "stat failed: $!";
396	print "size is ", -s _, "\n";	550	print "size is ", -s _, "\n";
397	};	551	};
398		552
		553
		554	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		555
		556	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		557	whether a file handle or path was passed.
		558
		559	On success, the callback is passed a hash reference with the following
		560	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		561	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		562	is passed.
		563
		564	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		565	C<ST_NOSUID>.
		566
		567	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		568	their correct value when available, or to C<0> on systems that do
		569	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		570	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		571	C<ST_NODIRATIME> and C<ST_RELATIME>.
		572
		573	Example: stat C</wd> and dump out the data if successful.
		574
		575	aio_statvfs "/wd", sub {
		576	my $f = $_[0]
		577	or die "statvfs: $!";
		578
		579	use Data::Dumper;
		580	say Dumper $f;
		581	};
		582
		583	# result:
		584	{
		585	bsize => 1024,
		586	bfree => 4333064312,
		587	blocks => 10253828096,
		588	files => 2050765568,
		589	flag => 4096,
		590	favail => 2042092649,
		591	bavail => 4333064312,
		592	ffree => 2042092649,
		593	namemax => 255,
		594	frsize => 1024,
		595	fsid => 1810
		596	}
		597
		598
		599	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		600
		601	Works like perl's C<utime> function (including the special case of $atime
		602	and $mtime being undef). Fractional times are supported if the underlying
		603	syscalls support them.
		604
		605	When called with a pathname, uses utimes(2) if available, otherwise
		606	utime(2). If called on a file descriptor, uses futimes(2) if available,
		607	otherwise returns ENOSYS, so this is not portable.
		608
		609	Examples:
		610
		611	# set atime and mtime to current time (basically touch(1)):
		612	aio_utime "path", undef, undef;
		613	# set atime to current time and mtime to beginning of the epoch:
		614	aio_utime "path", time, undef; # undef==0
		615
		616
		617	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		618
		619	Works like perl's C<chown> function, except that C<undef> for either $uid
		620	or $gid is being interpreted as "do not change" (but -1 can also be used).
		621
		622	Examples:
		623
		624	# same as "chown root path" in the shell:
		625	aio_chown "path", 0, -1;
		626	# same as above:
		627	aio_chown "path", 0, undef;
		628
		629
		630	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		631
		632	Works like truncate(2) or ftruncate(2).
		633
		634
		635	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		636
		637	Works like perl's C<chmod> function.
		638
		639
399	=item aio_unlink $pathname, $callback->($status)	640	=item aio_unlink $pathname, $callback->($status)
400		641
401	Asynchronously unlink (delete) a file and call the callback with the	642	Asynchronously unlink (delete) a file and call the callback with the
402	result code.	643	result code.
403		644
		645
404	=item aio_mknod $path, $mode, $dev, $callback->($status)	646	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
405		647
406	[EXPERIMENTAL]	648	[EXPERIMENTAL]
407		649
408	Asynchronously create a device node (or fifo). See mknod(2).	650	Asynchronously create a device node (or fifo). See mknod(2).
409		651
410	The only (POSIX-) portable way of calling this function is:	652	The only (POSIX-) portable way of calling this function is:
411		653
412	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	654	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		655
		656	See C<aio_stat> for info about some potentially helpful extra constants
		657	and functions.
413		658
414	=item aio_link $srcpath, $dstpath, $callback->($status)	659	=item aio_link $srcpath, $dstpath, $callback->($status)
415		660
416	Asynchronously create a new link to the existing object at C<$srcpath> at	661	Asynchronously create a new link to the existing object at C<$srcpath> at
417	the path C<$dstpath> and call the callback with the result code.	662	the path C<$dstpath> and call the callback with the result code.
418		663
		664
419	=item aio_symlink $srcpath, $dstpath, $callback->($status)	665	=item aio_symlink $srcpath, $dstpath, $callback->($status)
420		666
421	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	667	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
422	the path C<$dstpath> and call the callback with the result code.	668	the path C<$dstpath> and call the callback with the result code.
423		669
		670
424	=item aio_readlink $path, $callback->($link)	671	=item aio_readlink $pathname, $callback->($link)
425		672
426	Asynchronously read the symlink specified by C<$path> and pass it to	673	Asynchronously read the symlink specified by C<$path> and pass it to
427	the callback. If an error occurs, nothing or undef gets passed to the	674	the callback. If an error occurs, nothing or undef gets passed to the
428	callback.	675	callback.
429		676
		677
		678	=item aio_realpath $pathname, $callback->($path)
		679
		680	Asynchronously make the path absolute and resolve any symlinks in
		681	C<$path>. The resulting path only consists of directories (Same as
		682	L<Cwd::realpath>).
		683
		684	This request can be used to get the absolute path of the current working
		685	directory by passing it a path of F<.> (a single dot).
		686
		687
430	=item aio_rename $srcpath, $dstpath, $callback->($status)	688	=item aio_rename $srcpath, $dstpath, $callback->($status)
431		689
432	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	690	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
433	rename(2) and call the callback with the result code.	691	rename(2) and call the callback with the result code.
434		692
		693
		694	=item aio_mkdir $pathname, $mode, $callback->($status)
		695
		696	Asynchronously mkdir (create) a directory and call the callback with
		697	the result code. C<$mode> will be modified by the umask at the time the
		698	request is executed, so do not change your umask.
		699
		700
435	=item aio_rmdir $pathname, $callback->($status)	701	=item aio_rmdir $pathname, $callback->($status)
436		702
437	Asynchronously rmdir (delete) a directory and call the callback with the	703	Asynchronously rmdir (delete) a directory and call the callback with the
438	result code.	704	result code.
		705
439		706
440	=item aio_readdir $pathname, $callback->($entries)	707	=item aio_readdir $pathname, $callback->($entries)
441		708
442	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	709	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
443	directory (i.e. opendir + readdir + closedir). The entries will not be	710	directory (i.e. opendir + readdir + closedir). The entries will not be
444	sorted, and will B<NOT> include the C<.> and C<..> entries.	711	sorted, and will B<NOT> include the C<.> and C<..> entries.
445		712
446	The callback a single argument which is either C<undef> or an array-ref	713	The callback is passed a single argument which is either C<undef> or an
447	with the filenames.	714	array-ref with the filenames.
448		715
		716
		717	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		718
		719	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
		720	tune behaviour and output format. In case of an error, C<$entries> will be
		721	C<undef>.
		722
		723	The flags are a combination of the following constants, ORed together (the
		724	flags will also be passed to the callback, possibly modified):
		725
		726	=over 4
		727
		728	=item IO::AIO::READDIR_DENTS
		729
		730	When this flag is off, then the callback gets an arrayref consisting of
		731	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		732	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		733	entry in more detail.
		734
		735	C<$name> is the name of the entry.
		736
		737	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		738
		739	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		740	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		741	C<IO::AIO::DT_WHT>.
		742
		743	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		744	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		745	scalars are read-only: you can not modify them.
		746
		747	C<$inode> is the inode number (which might not be exact on systems with 64
		748	bit inode numbers and 32 bit perls). This field has unspecified content on
		749	systems that do not deliver the inode information.
		750
		751	=item IO::AIO::READDIR_DIRS_FIRST
		752
		753	When this flag is set, then the names will be returned in an order where
		754	likely directories come first, in optimal stat order. This is useful when
		755	you need to quickly find directories, or you want to find all directories
		756	while avoiding to stat() each entry.
		757
		758	If the system returns type information in readdir, then this is used
		759	to find directories directly. Otherwise, likely directories are names
		760	beginning with ".", or otherwise names with no dots, of which names with
		761	short names are tried first.
		762
		763	=item IO::AIO::READDIR_STAT_ORDER
		764
		765	When this flag is set, then the names will be returned in an order
		766	suitable for stat()'ing each one. That is, when you plan to stat()
		767	all files in the given directory, then the returned order will likely
		768	be fastest.
		769
		770	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		771	the likely dirs come first, resulting in a less optimal stat order.
		772
		773	=item IO::AIO::READDIR_FOUND_UNKNOWN
		774
		775	This flag should not be set when calling C<aio_readdirx>. Instead, it
		776	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		777	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
		778	C<$type>'s are known, which can be used to speed up some algorithms.
		779
		780	=back
		781
		782
449	=item aio_load $path, $data, $callback->($status)	783	=item aio_load $pathname, $data, $callback->($status)
450		784
451	This is a composite request that tries to fully load the given file into	785	This is a composite request that tries to fully load the given file into
452	memory. Status is the same as with aio_read.	786	memory. Status is the same as with aio_read.
453		787
454	=cut	788	=cut
455		789
456	sub aio_load($$;$) {	790	sub aio_load($$;$) {
457	aio_block {
458	my ($path, undef, $cb) = @_;	791	my ($path, undef, $cb) = @_;
459	my $data = \$_[1];	792	my $data = \$_[1];
460		793
461	my $pri = aioreq_pri;	794	my $pri = aioreq_pri;
462	my $grp = aio_group $cb;	795	my $grp = aio_group $cb;
		796
		797	aioreq_pri $pri;
		798	add $grp aio_open $path, O_RDONLY, 0, sub {
		799	my $fh = shift
		800	or return $grp->result (-1);
463		801
464	aioreq_pri $pri;	802	aioreq_pri $pri;
465	add $grp aio_open $path, O_RDONLY, 0, sub {
466	my ($fh) = @_
467	or return $grp->result (-1);
468
469	aioreq_pri $pri;
470	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {	803	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
471	$grp->result ($_[0]);	804	$grp->result ($_[0]);
472	};
473	};	805	};
474
475	$grp
476	}	806	};
		807
		808	$grp
477	}	809	}
478		810
479	=item aio_copy $srcpath, $dstpath, $callback->($status)	811	=item aio_copy $srcpath, $dstpath, $callback->($status)
480		812
481	Try to copy the I<file> (directories not supported as either source or	813	Try to copy the I<file> (directories not supported as either source or
482	destination) from C<$srcpath> to C<$dstpath> and call the callback with	814	destination) from C<$srcpath> to C<$dstpath> and call the callback with
483	the C<0> (error) or C<-1> ok.	815	a status of C<0> (ok) or C<-1> (error, see C<$!>).
484		816
485	This is a composite request that it creates the destination file with	817	This is a composite request that creates the destination file with
486	mode 0200 and copies the contents of the source file into it using	818	mode 0200 and copies the contents of the source file into it using
487	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	819	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
488	uid/gid, in that order.	820	uid/gid, in that order.
489		821
490	If an error occurs, the partial destination file will be unlinked, if	822	If an error occurs, the partial destination file will be unlinked, if
…		…
492	errors are being ignored.	824	errors are being ignored.
493		825
494	=cut	826	=cut
495		827
496	sub aio_copy($$;$) {	828	sub aio_copy($$;$) {
497	aio_block {
498	my ($src, $dst, $cb) = @_;	829	my ($src, $dst, $cb) = @_;
499		830
500	my $pri = aioreq_pri;	831	my $pri = aioreq_pri;
501	my $grp = aio_group $cb;	832	my $grp = aio_group $cb;
502		833
503	aioreq_pri $pri;	834	aioreq_pri $pri;
504	add $grp aio_open $src, O_RDONLY, 0, sub {	835	add $grp aio_open $src, O_RDONLY, 0, sub {
505	if (my $src_fh = $_[0]) {	836	if (my $src_fh = $_[0]) {
506	my @stat = stat $src_fh;	837	my @stat = stat $src_fh; # hmm, might block over nfs?
507		838
508	aioreq_pri $pri;	839	aioreq_pri $pri;
509	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	840	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
510	if (my $dst_fh = $_[0]) {	841	if (my $dst_fh = $_[0]) {
511	aioreq_pri $pri;	842	aioreq_pri $pri;
512	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	843	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
513	if ($_[0] == $stat[7]) {	844	if ($_[0] == $stat[7]) {
514	$grp->result (0);	845	$grp->result (0);
515	close $src_fh;	846	close $src_fh;
516		847
517	# those should not normally block. should. should.
518	utime $stat[8], $stat[9], $dst;
519	chmod $stat[2] & 07777, $dst_fh;
520	chown $stat[4], $stat[5], $dst_fh;
521	close $dst_fh;
522	} else {	848	my $ch = sub {
523	$grp->result (-1);
524	close $src_fh;
525	close $dst_fh;
526
527	aioreq $pri;	849	aioreq_pri $pri;
		850	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		851	aioreq_pri $pri;
		852	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		853	aioreq_pri $pri;
528	add $grp aio_unlink $dst;	854	add $grp aio_close $dst_fh;
		855	}
		856	};
529	}	857	};
		858
		859	aioreq_pri $pri;
		860	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		861	if ($_[0] < 0 && $! == ENOSYS) {
		862	aioreq_pri $pri;
		863	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		864	} else {
		865	$ch->();
		866	}
		867	};
		868	} else {
		869	$grp->result (-1);
		870	close $src_fh;
		871	close $dst_fh;
		872
		873	aioreq $pri;
		874	add $grp aio_unlink $dst;
530	};	875	}
531	} else {
532	$grp->result (-1);
533	}	876	};
		877	} else {
		878	$grp->result (-1);
534	},	879	}
535
536	} else {
537	$grp->result (-1);
538	}	880	},
		881
		882	} else {
		883	$grp->result (-1);
539	};	884	}
540
541	$grp
542	}	885	};
		886
		887	$grp
543	}	888	}
544		889
545	=item aio_move $srcpath, $dstpath, $callback->($status)	890	=item aio_move $srcpath, $dstpath, $callback->($status)
546		891
547	Try to move the I<file> (directories not supported as either source or	892	Try to move the I<file> (directories not supported as either source or
548	destination) from C<$srcpath> to C<$dstpath> and call the callback with	893	destination) from C<$srcpath> to C<$dstpath> and call the callback with
549	the C<0> (error) or C<-1> ok.	894	a status of C<0> (ok) or C<-1> (error, see C<$!>).
550		895
551	This is a composite request that tries to rename(2) the file first. If	896	This is a composite request that tries to rename(2) the file first; if
552	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if	897	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
553	that is successful, unlinking the C<$srcpath>.	898	that is successful, unlinks the C<$srcpath>.
554		899
555	=cut	900	=cut
556		901
557	sub aio_move($$;$) {	902	sub aio_move($$;$) {
558	aio_block {
559	my ($src, $dst, $cb) = @_;	903	my ($src, $dst, $cb) = @_;
560		904
561	my $pri = aioreq_pri;	905	my $pri = aioreq_pri;
562	my $grp = aio_group $cb;	906	my $grp = aio_group $cb;
563		907
564	aioreq_pri $pri;	908	aioreq_pri $pri;
565	add $grp aio_rename $src, $dst, sub {	909	add $grp aio_rename $src, $dst, sub {
566	if ($_[0] && $! == EXDEV) {	910	if ($_[0] && $! == EXDEV) {
567	aioreq_pri $pri;	911	aioreq_pri $pri;
568	add $grp aio_copy $src, $dst, sub {	912	add $grp aio_copy $src, $dst, sub {
569	$grp->result ($_[0]);
570
571	if (!$_[0]) {
572	aioreq_pri $pri;
573	add $grp aio_unlink $src;
574	}
575	};
576	} else {
577	$grp->result ($_[0]);	913	$grp->result ($_[0]);
		914
		915	unless ($_[0]) {
		916	aioreq_pri $pri;
		917	add $grp aio_unlink $src;
		918	}
578	}	919	};
		920	} else {
		921	$grp->result ($_[0]);
579	};	922	}
580
581	$grp
582	}	923	};
		924
		925	$grp
583	}	926	}
584		927
585	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	928	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
586		929
587	Scans a directory (similar to C<aio_readdir>) but additionally tries to	930	Scans a directory (similar to C<aio_readdir>) but additionally tries to
588	efficiently separate the entries of directory C<$path> into two sets of	931	efficiently separate the entries of directory C<$path> into two sets of
589	names, directories you can recurse into (directories), and ones you cannot	932	names, directories you can recurse into (directories), and ones you cannot
590	recurse into (everything else, including symlinks to directories).	933	recurse into (everything else, including symlinks to directories).
…		…
607		950
608	Implementation notes.	951	Implementation notes.
609		952
610	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	953	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
611		954
		955	If readdir returns file type information, then this is used directly to
		956	find directories.
		957
612	After reading the directory, the modification time, size etc. of the	958	Otherwise, after reading the directory, the modification time, size etc.
613	directory before and after the readdir is checked, and if they match (and	959	of the directory before and after the readdir is checked, and if they
614	isn't the current time), the link count will be used to decide how many	960	match (and isn't the current time), the link count will be used to decide
615	entries are directories (if >= 2). Otherwise, no knowledge of the number	961	how many entries are directories (if >= 2). Otherwise, no knowledge of the
616	of subdirectories will be assumed.	962	number of subdirectories will be assumed.
617		963
618	Then entries will be sorted into likely directories (everything without	964	Then entries will be sorted into likely directories a non-initial dot
619	a non-initial dot currently) and likely non-directories (everything	965	currently) and likely non-directories (see C<aio_readdirx>). Then every
620	else). Then every entry plus an appended C</.> will be C<stat>'ed,	966	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
621	likely directories first. If that succeeds, it assumes that the entry	967	in order of their inode numbers. If that succeeds, it assumes that the
622	is a directory or a symlink to directory (which will be checked	968	entry is a directory or a symlink to directory (which will be checked
623	seperately). This is often faster than stat'ing the entry itself because	969	separately). This is often faster than stat'ing the entry itself because
624	filesystems might detect the type of the entry without reading the inode	970	filesystems might detect the type of the entry without reading the inode
625	data (e.g. ext2fs filetype feature).	971	data (e.g. ext2fs filetype feature), even on systems that cannot return
		972	the filetype information on readdir.
626		973
627	If the known number of directories (link count - 2) has been reached, the	974	If the known number of directories (link count - 2) has been reached, the
628	rest of the entries is assumed to be non-directories.	975	rest of the entries is assumed to be non-directories.
629		976
630	This only works with certainty on POSIX (= UNIX) filesystems, which	977	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
634	as those tend to return 0 or 1 as link counts, which disables the	981	as those tend to return 0 or 1 as link counts, which disables the
635	directory counting heuristic.	982	directory counting heuristic.
636		983
637	=cut	984	=cut
638		985
639	sub aio_scandir($$$) {	986	sub aio_scandir($$;$) {
640	aio_block {
641	my ($path, $maxreq, $cb) = @_;	987	my ($path, $maxreq, $cb) = @_;
642		988
643	my $pri = aioreq_pri;	989	my $pri = aioreq_pri;
644		990
645	my $grp = aio_group $cb;	991	my $grp = aio_group $cb;
646		992
647	$maxreq = 4 if $maxreq <= 0;	993	$maxreq = 4 if $maxreq <= 0;
		994
		995	# get a wd object
		996	aioreq_pri $pri;
		997	add $grp aio_wd $path, sub {
		998	$_[0]
		999	or return $grp->result ();
		1000
		1001	my $wd = [shift, "."];
648		1002
649	# stat once	1003	# stat once
650	aioreq_pri $pri;	1004	aioreq_pri $pri;
651	add $grp aio_stat $path, sub {	1005	add $grp aio_stat $wd, sub {
652	return $grp->result () if $_[0];	1006	return $grp->result () if $_[0];
653	my $now = time;	1007	my $now = time;
654	my $hash1 = join ":", (stat _)[0,1,3,7,9];	1008	my $hash1 = join ":", (stat _)[0,1,3,7,9];
655		1009
656	# read the directory entries	1010	# read the directory entries
657	aioreq_pri $pri;	1011	aioreq_pri $pri;
658	add $grp aio_readdir $path, sub {	1012	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
659	my $entries = shift	1013	my $entries = shift
660	or return $grp->result ();	1014	or return $grp->result ();
661		1015
662	# stat the dir another time	1016	# stat the dir another time
663	aioreq_pri $pri;	1017	aioreq_pri $pri;
664	add $grp aio_stat $path, sub {	1018	add $grp aio_stat $wd, sub {
665	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1019	my $hash2 = join ":", (stat _)[0,1,3,7,9];
666		1020
667	my $ndirs;	1021	my $ndirs;
668		1022
669	# take the slow route if anything looks fishy	1023	# take the slow route if anything looks fishy
670	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1024	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
671	$ndirs = -1;	1025	$ndirs = -1;
672	} else {	1026	} else {
673	# if nlink == 2, we are finished	1027	# if nlink == 2, we are finished
674	# on non-posix-fs's, we rely on nlink < 2	1028	# for non-posix-fs's, we rely on nlink < 2
675	$ndirs = (stat _)[3] - 2	1029	$ndirs = (stat _)[3] - 2
676	or return $grp->result ([], $entries);	1030	or return $grp->result ([], $entries);
677	}	1031	}
678		1032
679	# sort into likely dirs and likely nondirs
680	# dirs == files without ".", short entries first
681	$entries = [map $_->[0],
682	sort { $b->[1] cmp $a->[1] }
683	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
684	@$entries];
685
686	my (@dirs, @nondirs);	1033	my (@dirs, @nondirs);
687		1034
688	my $statgrp = add $grp aio_group sub {	1035	my $statgrp = add $grp aio_group sub {
689	$grp->result (\@dirs, \@nondirs);	1036	$grp->result (\@dirs, \@nondirs);
690	};	1037	};
691		1038
692	limit $statgrp $maxreq;	1039	limit $statgrp $maxreq;
693	feed $statgrp sub {	1040	feed $statgrp sub {
694	return unless @$entries;	1041	return unless @$entries;
695	my $entry = pop @$entries;	1042	my $entry = shift @$entries;
696		1043
697	aioreq_pri $pri;	1044	aioreq_pri $pri;
		1045	$wd->[1] = "$entry/.";
698	add $statgrp aio_stat "$path/$entry/.", sub {	1046	add $statgrp aio_stat $wd, sub {
699	if ($_[0] < 0) {	1047	if ($_[0] < 0) {
700	push @nondirs, $entry;	1048	push @nondirs, $entry;
701	} else {	1049	} else {
702	# need to check for real directory	1050	# need to check for real directory
703	aioreq_pri $pri;	1051	aioreq_pri $pri;
		1052	$wd->[1] = $entry;
704	add $statgrp aio_lstat "$path/$entry", sub {	1053	add $statgrp aio_lstat $wd, sub {
705	if (-d _) {	1054	if (-d _) {
706	push @dirs, $entry;	1055	push @dirs, $entry;
707		1056
708	unless (--$ndirs) {	1057	unless (--$ndirs) {
709	push @nondirs, @$entries;	1058	push @nondirs, @$entries;
…		…
717	};	1066	};
718	};	1067	};
719	};	1068	};
720	};	1069	};
721	};	1070	};
722
723	$grp
724	}	1071	};
		1072
		1073	$grp
725	}	1074	}
726		1075
727	=item aio_rmtree $path, $callback->($status)	1076	=item aio_rmtree $pathname, $callback->($status)
728		1077
729	Delete a directory tree starting (and including) C<$path>, return the status of the final C<rmdir> only.	1078	Delete a directory tree starting (and including) C<$path>, return the
		1079	status of the final C<rmdir> only. This is a composite request that
730	This is a composite request that uses C<aio_scandir> to recurse into and rmdir directories, and	1080	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
731	unlink everything else.	1081	everything else.
732		1082
733	=cut	1083	=cut
734		1084
735	sub aio_rmtree;	1085	sub aio_rmtree;
736	sub aio_rmtree {	1086	sub aio_rmtree($;$) {
737	aio_block {
738	my ($path, $cb) = @_;	1087	my ($path, $cb) = @_;
739		1088
740	my $pri = aioreq_pri;	1089	my $pri = aioreq_pri;
741	my $grp = aio_group $cb;	1090	my $grp = aio_group $cb;
742		1091
743	aioreq_pri $pri;	1092	aioreq_pri $pri;
744	add $grp aio_scandir $path, 0, sub {	1093	add $grp aio_scandir $path, 0, sub {
745	my ($dirs, $nondirs) = @_;	1094	my ($dirs, $nondirs) = @_;
746		1095
747	my $dirgrp = aio_group sub {	1096	my $dirgrp = aio_group sub {
748	add $grp aio_rmdir $path, sub {	1097	add $grp aio_rmdir $path, sub {
749	$grp->result ($_[0]);	1098	$grp->result ($_[0]);
750	};
751	};	1099	};
752
753	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
754	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
755
756	add $grp $dirgrp;
757	};	1100	};
758		1101
759	$grp	1102	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1103	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1104
		1105	add $grp $dirgrp;
760	}	1106	};
		1107
		1108	$grp
761	}	1109	}
		1110
		1111	=item aio_sync $callback->($status)
		1112
		1113	Asynchronously call sync and call the callback when finished.
762		1114
763	=item aio_fsync $fh, $callback->($status)	1115	=item aio_fsync $fh, $callback->($status)
764		1116
765	Asynchronously call fsync on the given filehandle and call the callback	1117	Asynchronously call fsync on the given filehandle and call the callback
766	with the fsync result code.	1118	with the fsync result code.
…		…
770	Asynchronously call fdatasync on the given filehandle and call the	1122	Asynchronously call fdatasync on the given filehandle and call the
771	callback with the fdatasync result code.	1123	callback with the fdatasync result code.
772		1124
773	If this call isn't available because your OS lacks it or it couldn't be	1125	If this call isn't available because your OS lacks it or it couldn't be
774	detected, it will be emulated by calling C<fsync> instead.	1126	detected, it will be emulated by calling C<fsync> instead.
		1127
		1128	=item aio_syncfs $fh, $callback->($status)
		1129
		1130	Asynchronously call the syncfs syscall to sync the filesystem associated
		1131	to the given filehandle and call the callback with the syncfs result
		1132	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1133	errno to C<ENOSYS> nevertheless.
		1134
		1135	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1136
		1137	Sync the data portion of the file specified by C<$offset> and C<$length>
		1138	to disk (but NOT the metadata), by calling the Linux-specific
		1139	sync_file_range call. If sync_file_range is not available or it returns
		1140	ENOSYS, then fdatasync or fsync is being substituted.
		1141
		1142	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1143	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1144	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1145	manpage for details.
		1146
		1147	=item aio_pathsync $pathname, $callback->($status)
		1148
		1149	This request tries to open, fsync and close the given path. This is a
		1150	composite request intended to sync directories after directory operations
		1151	(E.g. rename). This might not work on all operating systems or have any
		1152	specific effect, but usually it makes sure that directory changes get
		1153	written to disc. It works for anything that can be opened for read-only,
		1154	not just directories.
		1155
		1156	Future versions of this function might fall back to other methods when
		1157	C<fsync> on the directory fails (such as calling C<sync>).
		1158
		1159	Passes C<0> when everything went ok, and C<-1> on error.
		1160
		1161	=cut
		1162
		1163	sub aio_pathsync($;$) {
		1164	my ($path, $cb) = @_;
		1165
		1166	my $pri = aioreq_pri;
		1167	my $grp = aio_group $cb;
		1168
		1169	aioreq_pri $pri;
		1170	add $grp aio_open $path, O_RDONLY, 0, sub {
		1171	my ($fh) = @_;
		1172	if ($fh) {
		1173	aioreq_pri $pri;
		1174	add $grp aio_fsync $fh, sub {
		1175	$grp->result ($_[0]);
		1176
		1177	aioreq_pri $pri;
		1178	add $grp aio_close $fh;
		1179	};
		1180	} else {
		1181	$grp->result (-1);
		1182	}
		1183	};
		1184
		1185	$grp
		1186	}
		1187
		1188	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1189
		1190	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1191	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1192	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1193	scalar must only be modified in-place while an aio operation is pending on
		1194	it).
		1195
		1196	It calls the C<msync> function of your OS, if available, with the memory
		1197	area starting at C<$offset> in the string and ending C<$length> bytes
		1198	later. If C<$length> is negative, counts from the end, and if C<$length>
		1199	is C<undef>, then it goes till the end of the string. The flags can be
		1200	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1201	C<IO::AIO::MS_SYNC>.
		1202
		1203	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1204
		1205	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1206	scalars.
		1207
		1208	It touches (reads or writes) all memory pages in the specified
		1209	range inside the scalar. All caveats and parameters are the same
		1210	as for C<aio_msync>, above, except for flags, which must be either
		1211	C<0> (which reads all pages and ensures they are instantiated) or
		1212	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1213	writing an octet from it, which dirties the page).
		1214
		1215	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1216
		1217	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1218	scalars.
		1219
		1220	It reads in all the pages of the underlying storage into memory (if any)
		1221	and locks them, so they are not getting swapped/paged out or removed.
		1222
		1223	If C<$length> is undefined, then the scalar will be locked till the end.
		1224
		1225	On systems that do not implement C<mlock>, this function returns C<-1>
		1226	and sets errno to C<ENOSYS>.
		1227
		1228	Note that the corresponding C<munlock> is synchronous and is
		1229	documented under L<MISCELLANEOUS FUNCTIONS>.
		1230
		1231	Example: open a file, mmap and mlock it - both will be undone when
		1232	C<$data> gets destroyed.
		1233
		1234	open my $fh, "<", $path or die "$path: $!";
		1235	my $data;
		1236	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1237	aio_mlock $data; # mlock in background
		1238
		1239	=item aio_mlockall $flags, $callback->($status)
		1240
		1241	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1242	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1243
		1244	On systems that do not implement C<mlockall>, this function returns C<-1>
		1245	and sets errno to C<ENOSYS>.
		1246
		1247	Note that the corresponding C<munlockall> is synchronous and is
		1248	documented under L<MISCELLANEOUS FUNCTIONS>.
		1249
		1250	Example: asynchronously lock all current and future pages into memory.
		1251
		1252	aio_mlockall IO::AIO::MCL_FUTURE;
775		1253
776	=item aio_group $callback->(...)	1254	=item aio_group $callback->(...)
777		1255
778	This is a very special aio request: Instead of doing something, it is a	1256	This is a very special aio request: Instead of doing something, it is a
779	container for other aio requests, which is useful if you want to bundle	1257	container for other aio requests, which is useful if you want to bundle
…		…
817	immense (it blocks a thread for a long time) so do not use this function	1295	immense (it blocks a thread for a long time) so do not use this function
818	except to put your application under artificial I/O pressure.	1296	except to put your application under artificial I/O pressure.
819		1297
820	=back	1298	=back
821		1299
		1300
		1301	=head2 IO::AIO::WD - multiple working directories
		1302
		1303	Your process only has one current working directory, which is used by all
		1304	threads. This makes it hard to use relative paths (some other component
		1305	could call C<chdir> at any time, and it is hard to control when the path
		1306	will be used by IO::AIO).
		1307
		1308	One solution for this is to always use absolute paths. This usually works,
		1309	but can be quite slow (the kernel has to walk the whole path on every
		1310	access), and can also be a hassle to implement.
		1311
		1312	Newer POSIX systems have a number of functions (openat, fdopendir,
		1313	futimensat and so on) that make it possible to specify working directories
		1314	per operation.
		1315
		1316	For portability, and because the clowns who "designed", or shall I write,
		1317	perpetrated this new interface were obviously half-drunk, this abstraction
		1318	cannot be perfect, though.
		1319
		1320	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1321	object. This object stores the canonicalised, absolute version of the
		1322	path, and on systems that allow it, also a directory file descriptor.
		1323
		1324	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1325	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1326	object and a pathname instead (or the IO::AIO::WD object alone, which
		1327	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1328	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1329	to that IO::AIO::WD object.
		1330
		1331	For example, to get a wd object for F</etc> and then stat F<passwd>
		1332	inside, you would write:
		1333
		1334	aio_wd "/etc", sub {
		1335	my $etcdir = shift;
		1336
		1337	# although $etcdir can be undef on error, there is generally no reason
		1338	# to check for errors here, as aio_stat will fail with ENOENT
		1339	# when $etcdir is undef.
		1340
		1341	aio_stat [$etcdir, "passwd"], sub {
		1342	# yay
		1343	};
		1344	};
		1345
		1346	That C<aio_wd> is a request and not a normal function shows that creating
		1347	an IO::AIO::WD object is itself a potentially blocking operation, which is
		1348	why it is done asynchronously.
		1349
		1350	To stat the directory obtained with C<aio_wd> above, one could write
		1351	either of the following three request calls:
		1352
		1353	aio_lstat "/etc" , sub { ... # pathname as normal string
		1354	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1355	aio_lstat $wd , sub { ... # shorthand for the previous
		1356
		1357	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1358	object and the pathname string, so you could write the following without
		1359	causing any issues due to C<$path> getting reused:
		1360
		1361	my $path = [$wd, undef];
		1362
		1363	for my $name (qw(abc def ghi)) {
		1364	$path->[1] = $name;
		1365	aio_stat $path, sub {
		1366	# ...
		1367	};
		1368	}
		1369
		1370	There are some caveats: when directories get renamed (or deleted), the
		1371	pathname string doesn't change, so will point to the new directory (or
		1372	nowhere at all), while the directory fd, if available on the system,
		1373	will still point to the original directory. Most functions accepting a
		1374	pathname will use the directory fd on newer systems, and the string on
		1375	older systems. Some functions (such as realpath) will always rely on the
		1376	string form of the pathname.
		1377
		1378	So this fucntionality is mainly useful to get some protection against
		1379	C<chdir>, to easily get an absolute path out of a relative path for future
		1380	reference, and to speed up doing many operations in the same directory
		1381	(e.g. when stat'ing all files in a directory).
		1382
		1383	The following functions implement this working directory abstraction:
		1384
		1385	=over 4
		1386
		1387	=item aio_wd $pathname, $callback->($wd)
		1388
		1389	Asynchonously canonicalise the given pathname and convert it to an
		1390	IO::AIO::WD object representing it. If possible and supported on the
		1391	system, also open a directory fd to speed up pathname resolution relative
		1392	to this working directory.
		1393
		1394	If something goes wrong, then C<undef> is passwd to the callback instead
		1395	of a working directory object and C<$!> is set appropriately. Since
		1396	passing C<undef> as working directory component of a pathname fails the
		1397	request with C<ENOENT>, there is often no need for error checking in the
		1398	C<aio_wd> callback, as future requests using the value will fail in the
		1399	expected way.
		1400
		1401	If this call isn't available because your OS lacks it or it couldn't be
		1402	detected, it will be emulated by calling C<fsync> instead.
		1403
		1404	=item IO::AIO::CWD
		1405
		1406	This is a compiletime constant (object) that represents the process
		1407	current working directory.
		1408
		1409	Specifying this object as working directory object for a pathname is as
		1410	if the pathname would be specified directly, without a directory object,
		1411	e.g., these calls are functionally identical:
		1412
		1413	aio_stat "somefile", sub { ... };
		1414	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1415
		1416	=back
		1417
		1418
822	=head2 IO::AIO::REQ CLASS	1419	=head2 IO::AIO::REQ CLASS
823		1420
824	All non-aggregate C<aio_*> functions return an object of this class when	1421	All non-aggregate C<aio_*> functions return an object of this class when
825	called in non-void context.	1422	called in non-void context.
826		1423
…		…
829	=item cancel $req	1426	=item cancel $req
830		1427
831	Cancels the request, if possible. Has the effect of skipping execution	1428	Cancels the request, if possible. Has the effect of skipping execution
832	when entering the B<execute> state and skipping calling the callback when	1429	when entering the B<execute> state and skipping calling the callback when
833	entering the the B<result> state, but will leave the request otherwise	1430	entering the the B<result> state, but will leave the request otherwise
834	untouched. That means that requests that currently execute will not be	1431	untouched (with the exception of readdir). That means that requests that
835	stopped and resources held by the request will not be freed prematurely.	1432	currently execute will not be stopped and resources held by the request
		1433	will not be freed prematurely.
836		1434
837	=item cb $req $callback->(...)	1435	=item cb $req $callback->(...)
838		1436
839	Replace (or simply set) the callback registered to the request.	1437	Replace (or simply set) the callback registered to the request.
840		1438
…		…
891	Their lifetime, simplified, looks like this: when they are empty, they	1489	Their lifetime, simplified, looks like this: when they are empty, they
892	will finish very quickly. If they contain only requests that are in the	1490	will finish very quickly. If they contain only requests that are in the
893	C<done> state, they will also finish. Otherwise they will continue to	1491	C<done> state, they will also finish. Otherwise they will continue to
894	exist.	1492	exist.
895		1493
896	That means after creating a group you have some time to add requests. And	1494	That means after creating a group you have some time to add requests
897	in the callbacks of those requests, you can add further requests to the	1495	(precisely before the callback has been invoked, which is only done within
898	group. And only when all those requests have finished will the the group	1496	the C<poll_cb>). And in the callbacks of those requests, you can add
899	itself finish.	1497	further requests to the group. And only when all those requests have
		1498	finished will the the group itself finish.
900		1499
901	=over 4	1500	=over 4
902		1501
903	=item add $grp ...	1502	=item add $grp ...
904		1503
…		…
913	=item $grp->cancel_subs	1512	=item $grp->cancel_subs
914		1513
915	Cancel all subrequests and clears any feeder, but not the group request	1514	Cancel all subrequests and clears any feeder, but not the group request
916	itself. Useful when you queued a lot of events but got a result early.	1515	itself. Useful when you queued a lot of events but got a result early.
917		1516
		1517	The group request will finish normally (you cannot add requests to the
		1518	group).
		1519
918	=item $grp->result (...)	1520	=item $grp->result (...)
919		1521
920	Set the result value(s) that will be passed to the group callback when all	1522	Set the result value(s) that will be passed to the group callback when all
921	subrequests have finished and set thre groups errno to the current value	1523	subrequests have finished and set the groups errno to the current value
922	of errno (just like calling C<errno> without an error number). By default,	1524	of errno (just like calling C<errno> without an error number). By default,
923	no argument will be passed and errno is zero.	1525	no argument will be passed and errno is zero.
924		1526
925	=item $grp->errno ([$errno])	1527	=item $grp->errno ([$errno])
926		1528
…		…
937	=item feed $grp $callback->($grp)	1539	=item feed $grp $callback->($grp)
938		1540
939	Sets a feeder/generator on this group: every group can have an attached	1541	Sets a feeder/generator on this group: every group can have an attached
940	generator that generates requests if idle. The idea behind this is that,	1542	generator that generates requests if idle. The idea behind this is that,
941	although you could just queue as many requests as you want in a group,	1543	although you could just queue as many requests as you want in a group,
942	this might starve other requests for a potentially long time. For	1544	this might starve other requests for a potentially long time. For example,
943	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1545	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
944	requests, delaying any later requests for a long time.	1546	requests, delaying any later requests for a long time.
945		1547
946	To avoid this, and allow incremental generation of requests, you can	1548	To avoid this, and allow incremental generation of requests, you can
947	instead a group and set a feeder on it that generates those requests. The	1549	instead a group and set a feeder on it that generates those requests. The
948	feed callback will be called whenever there are few enough (see C<limit>,	1550	feed callback will be called whenever there are few enough (see C<limit>,
…		…
953	not impose any limits).	1555	not impose any limits).
954		1556
955	If the feed does not queue more requests when called, it will be	1557	If the feed does not queue more requests when called, it will be
956	automatically removed from the group.	1558	automatically removed from the group.
957		1559
958	If the feed limit is C<0>, it will be set to C<2> automatically.	1560	If the feed limit is C<0> when this method is called, it will be set to
		1561	C<2> automatically.
959		1562
960	Example:	1563	Example:
961		1564
962	# stat all files in @files, but only ever use four aio requests concurrently:	1565	# stat all files in @files, but only ever use four aio requests concurrently:
963		1566
…		…
975	Sets the feeder limit for the group: The feeder will be called whenever	1578	Sets the feeder limit for the group: The feeder will be called whenever
976	the group contains less than this many requests.	1579	the group contains less than this many requests.
977		1580
978	Setting the limit to C<0> will pause the feeding process.	1581	Setting the limit to C<0> will pause the feeding process.
979		1582
		1583	The default value for the limit is C<0>, but note that setting a feeder
		1584	automatically bumps it up to C<2>.
		1585
980	=back	1586	=back
981		1587
982	=head2 SUPPORT FUNCTIONS	1588	=head2 SUPPORT FUNCTIONS
983		1589
984	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1590	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
…		…
986	=over 4	1592	=over 4
987		1593
988	=item $fileno = IO::AIO::poll_fileno	1594	=item $fileno = IO::AIO::poll_fileno
989		1595
990	Return the I<request result pipe file descriptor>. This filehandle must be	1596	Return the I<request result pipe file descriptor>. This filehandle must be
991	polled for reading by some mechanism outside this module (e.g. Event or	1597	polled for reading by some mechanism outside this module (e.g. EV, Glib,
992	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1598	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
993	to call C<poll_cb> to check the results.	1599	you have to call C<poll_cb> to check the results.
994		1600
995	See C<poll_cb> for an example.	1601	See C<poll_cb> for an example.
996		1602
997	=item IO::AIO::poll_cb	1603	=item IO::AIO::poll_cb
998		1604
999	Process some outstanding events on the result pipe. You have to call this	1605	Process some outstanding events on the result pipe. You have to call
1000	regularly. Returns the number of events processed. Returns immediately	1606	this regularly. Returns C<0> if all events could be processed (or there
1001	when no events are outstanding. The amount of events processed depends on	1607	were no events to process), or C<-1> if it returned earlier for whatever
1002	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.	1608	reason. Returns immediately when no events are outstanding. The amount of
		1609	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1610	C<IO::AIO::max_poll_time>.
1003		1611
1004	If not all requests were processed for whatever reason, the filehandle	1612	If not all requests were processed for whatever reason, the filehandle
1005	will still be ready when C<poll_cb> returns.	1613	will still be ready when C<poll_cb> returns, so normally you don't have to
		1614	do anything special to have it called later.
		1615
		1616	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1617	ready, it can be beneficial to call this function from loops which submit
		1618	a lot of requests, to make sure the results get processed when they become
		1619	available and not just when the loop is finished and the event loop takes
		1620	over again. This function returns very fast when there are no outstanding
		1621	requests.
1006		1622
1007	Example: Install an Event watcher that automatically calls	1623	Example: Install an Event watcher that automatically calls
1008	IO::AIO::poll_cb with high priority:	1624	IO::AIO::poll_cb with high priority (more examples can be found in the
		1625	SYNOPSIS section, at the top of this document):
1009		1626
1010	Event->io (fd => IO::AIO::poll_fileno,	1627	Event->io (fd => IO::AIO::poll_fileno,
1011	poll => 'r', async => 1,	1628	poll => 'r', async => 1,
1012	cb => \&IO::AIO::poll_cb);	1629	cb => \&IO::AIO::poll_cb);
		1630
		1631	=item IO::AIO::poll_wait
		1632
		1633	If there are any outstanding requests and none of them in the result
		1634	phase, wait till the result filehandle becomes ready for reading (simply
		1635	does a C<select> on the filehandle. This is useful if you want to
		1636	synchronously wait for some requests to finish).
		1637
		1638	See C<nreqs> for an example.
		1639
		1640	=item IO::AIO::poll
		1641
		1642	Waits until some requests have been handled.
		1643
		1644	Returns the number of requests processed, but is otherwise strictly
		1645	equivalent to:
		1646
		1647	IO::AIO::poll_wait, IO::AIO::poll_cb
		1648
		1649	=item IO::AIO::flush
		1650
		1651	Wait till all outstanding AIO requests have been handled.
		1652
		1653	Strictly equivalent to:
		1654
		1655	IO::AIO::poll_wait, IO::AIO::poll_cb
		1656	while IO::AIO::nreqs;
1013		1657
1014	=item IO::AIO::max_poll_reqs $nreqs	1658	=item IO::AIO::max_poll_reqs $nreqs
1015		1659
1016	=item IO::AIO::max_poll_time $seconds	1660	=item IO::AIO::max_poll_time $seconds
1017		1661
…		…
1042	# use a low priority so other tasks have priority	1686	# use a low priority so other tasks have priority
1043	Event->io (fd => IO::AIO::poll_fileno,	1687	Event->io (fd => IO::AIO::poll_fileno,
1044	poll => 'r', nice => 1,	1688	poll => 'r', nice => 1,
1045	cb => &IO::AIO::poll_cb);	1689	cb => &IO::AIO::poll_cb);
1046		1690
1047	=item IO::AIO::poll_wait	1691	=back
1048
1049	If there are any outstanding requests and none of them in the result
1050	phase, wait till the result filehandle becomes ready for reading (simply
1051	does a C<select> on the filehandle. This is useful if you want to
1052	synchronously wait for some requests to finish).
1053
1054	See C<nreqs> for an example.
1055
1056	=item IO::AIO::poll
1057
1058	Waits until some requests have been handled.
1059
1060	Returns the number of requests processed, but is otherwise strictly
1061	equivalent to:
1062
1063	IO::AIO::poll_wait, IO::AIO::poll_cb
1064
1065	=item IO::AIO::flush
1066
1067	Wait till all outstanding AIO requests have been handled.
1068
1069	Strictly equivalent to:
1070
1071	IO::AIO::poll_wait, IO::AIO::poll_cb
1072	while IO::AIO::nreqs;
1073		1692
1074	=head3 CONTROLLING THE NUMBER OF THREADS	1693	=head3 CONTROLLING THE NUMBER OF THREADS
		1694
		1695	=over
1075		1696
1076	=item IO::AIO::min_parallel $nthreads	1697	=item IO::AIO::min_parallel $nthreads
1077		1698
1078	Set the minimum number of AIO threads to C<$nthreads>. The current	1699	Set the minimum number of AIO threads to C<$nthreads>. The current
1079	default is C<8>, which means eight asynchronous operations can execute	1700	default is C<8>, which means eight asynchronous operations can execute
…		…
1107		1728
1108	Under normal circumstances you don't need to call this function.	1729	Under normal circumstances you don't need to call this function.
1109		1730
1110	=item IO::AIO::max_idle $nthreads	1731	=item IO::AIO::max_idle $nthreads
1111		1732
1112	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1733	Limit the number of threads (default: 4) that are allowed to idle
1113	threads that did not get a request to process within 10 seconds). That	1734	(i.e., threads that did not get a request to process within the idle
1114	means if a thread becomes idle while C<$nthreads> other threads are also	1735	timeout (default: 10 seconds). That means if a thread becomes idle while
1115	idle, it will free its resources and exit.	1736	C<$nthreads> other threads are also idle, it will free its resources and
		1737	exit.
1116		1738
1117	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1739	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1118	to allow for extremely high load situations, but want to free resources	1740	to allow for extremely high load situations, but want to free resources
1119	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1741	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1120		1742
1121	The default is probably ok in most situations, especially if thread	1743	The default is probably ok in most situations, especially if thread
1122	creation is fast. If thread creation is very slow on your system you might	1744	creation is fast. If thread creation is very slow on your system you might
1123	want to use larger values.	1745	want to use larger values.
1124		1746
		1747	=item IO::AIO::idle_timeout $seconds
		1748
		1749	Sets the minimum idle timeout (default 10) after which worker threads are
		1750	allowed to exit. SEe C<IO::AIO::max_idle>.
		1751
1125	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1752	=item IO::AIO::max_outstanding $maxreqs
		1753
		1754	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1755	you do queue up more than this number of requests, the next call to
		1756	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1757	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1758	longer exceeded.
		1759
		1760	In other words, this setting does not enforce a queue limit, but can be
		1761	used to make poll functions block if the limit is exceeded.
1126		1762
1127	This is a very bad function to use in interactive programs because it	1763	This is a very bad function to use in interactive programs because it
1128	blocks, and a bad way to reduce concurrency because it is inexact: Better	1764	blocks, and a bad way to reduce concurrency because it is inexact: Better
1129	use an C<aio_group> together with a feed callback.	1765	use an C<aio_group> together with a feed callback.
1130		1766
1131	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1767	It's main use is in scripts without an event loop - when you want to stat
1132	to queue up more than this number of requests, the next call to the	1768	a lot of files, you can write somehting like this:
1133	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1134	function will block until the limit is no longer exceeded.
1135		1769
1136	The default value is very large, so there is no practical limit on the	1770	IO::AIO::max_outstanding 32;
1137	number of outstanding requests.
1138		1771
1139	You can still queue as many requests as you want. Therefore,	1772	for my $path (...) {
1140	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	1773	aio_stat $path , ...;
1141	as a stop gap to shield against fatal memory overflow (with large values).	1774	IO::AIO::poll_cb;
		1775	}
		1776
		1777	IO::AIO::flush;
		1778
		1779	The call to C<poll_cb> inside the loop will normally return instantly, but
		1780	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1781	some requests have been handled. This keeps the loop from pushing a large
		1782	number of C<aio_stat> requests onto the queue.
		1783
		1784	The default value for C<max_outstanding> is very large, so there is no
		1785	practical limit on the number of outstanding requests.
		1786
		1787	=back
1142		1788
1143	=head3 STATISTICAL INFORMATION	1789	=head3 STATISTICAL INFORMATION
		1790
		1791	=over
1144		1792
1145	=item IO::AIO::nreqs	1793	=item IO::AIO::nreqs
1146		1794
1147	Returns the number of requests currently in the ready, execute or pending	1795	Returns the number of requests currently in the ready, execute or pending
1148	states (i.e. for which their callback has not been invoked yet).	1796	states (i.e. for which their callback has not been invoked yet).
…		…
1162	Returns the number of requests currently in the pending state (executed,	1810	Returns the number of requests currently in the pending state (executed,
1163	but not yet processed by poll_cb).	1811	but not yet processed by poll_cb).
1164		1812
1165	=back	1813	=back
1166		1814
		1815	=head3 MISCELLANEOUS FUNCTIONS
		1816
		1817	IO::AIO implements some functions that might be useful, but are not
		1818	asynchronous.
		1819
		1820	=over 4
		1821
		1822	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1823
		1824	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1825	but is blocking (this makes most sense if you know the input data is
		1826	likely cached already and the output filehandle is set to non-blocking
		1827	operations).
		1828
		1829	Returns the number of bytes copied, or C<-1> on error.
		1830
		1831	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1832
		1833	Simply calls the C<posix_fadvise> function (see its
		1834	manpage for details). The following advice constants are
		1835	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1836	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1837	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1838
		1839	On systems that do not implement C<posix_fadvise>, this function returns
		1840	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1841
		1842	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1843
		1844	Simply calls the C<posix_madvise> function (see its
		1845	manpage for details). The following advice constants are
		1846	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1847	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1848
		1849	On systems that do not implement C<posix_madvise>, this function returns
		1850	ENOSYS, otherwise the return value of C<posix_madvise>.
		1851
		1852	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1853
		1854	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1855	$scalar (see its manpage for details). The following protect
		1856	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1857	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1858
		1859	On systems that do not implement C<mprotect>, this function returns
		1860	ENOSYS, otherwise the return value of C<mprotect>.
		1861
		1862	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1863
		1864	Memory-maps a file (or anonymous memory range) and attaches it to the
		1865	given C<$scalar>, which will act like a string scalar.
		1866
		1867	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1868	change the string length, and most read-only operations such as copying it
		1869	or searching it with regexes and so on.
		1870
		1871	Anything else is unsafe and will, at best, result in memory leaks.
		1872
		1873	The memory map associated with the C<$scalar> is automatically removed
		1874	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1875	C<IO::AIO::munmap> functions are called.
		1876
		1877	This calls the C<mmap>(2) function internally. See your system's manual
		1878	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1879
		1880	The C<$length> must be larger than zero and smaller than the actual
		1881	filesize.
		1882
		1883	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1884	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1885
		1886	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1887	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1888	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1889	(which is set to C<MAP_ANON> if your system only provides this
		1890	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1891	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1892	C<IO::AIO::MAP_NONBLOCK>
		1893
		1894	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1895
		1896	C<$offset> is the offset from the start of the file - it generally must be
		1897	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1898
		1899	Example:
		1900
		1901	use Digest::MD5;
		1902	use IO::AIO;
		1903
		1904	open my $fh, "<verybigfile"
		1905	or die "$!";
		1906
		1907	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1908	or die "verybigfile: $!";
		1909
		1910	my $fast_md5 = md5 $data;
		1911
		1912	=item IO::AIO::munmap $scalar
		1913
		1914	Removes a previous mmap and undefines the C<$scalar>.
		1915
		1916	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1917
		1918	Calls the C<munlock> function, undoing the effects of a previous
		1919	C<aio_mlock> call (see its description for details).
		1920
		1921	=item IO::AIO::munlockall
		1922
		1923	Calls the C<munlockall> function.
		1924
		1925	On systems that do not implement C<munlockall>, this function returns
		1926	ENOSYS, otherwise the return value of C<munlockall>.
		1927
		1928	=back
		1929
1167	=cut	1930	=cut
1168		1931
1169	# support function to convert a fd into a perl filehandle
1170	sub _fd2fh {
1171	return undef if $_[0] < 0;
1172
1173	# try to generate nice filehandles
1174	my $sym = "IO::AIO::fd#$_[0]";
1175	local *$sym;
1176
1177	open *$sym, "+<&=$_[0]" # usually works under any unix
1178	or open *$sym, "<&=$_[0]" # cygwin needs this
1179	or open *$sym, ">&=$_[0]" # or this
1180	or return undef;
1181
1182	*$sym
1183	}
1184
1185	min_parallel 8;	1932	min_parallel 8;
1186		1933
1187	END { flush }	1934	END { flush }
1188		1935
1189	1;	1936	1;
1190		1937
		1938	=head1 EVENT LOOP INTEGRATION
		1939
		1940	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1941	automatically into many event loops:
		1942
		1943	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1944	use AnyEvent::AIO;
		1945
		1946	You can also integrate IO::AIO manually into many event loops, here are
		1947	some examples of how to do this:
		1948
		1949	# EV integration
		1950	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1951
		1952	# Event integration
		1953	Event->io (fd => IO::AIO::poll_fileno,
		1954	poll => 'r',
		1955	cb => \&IO::AIO::poll_cb);
		1956
		1957	# Glib/Gtk2 integration
		1958	add_watch Glib::IO IO::AIO::poll_fileno,
		1959	in => sub { IO::AIO::poll_cb; 1 };
		1960
		1961	# Tk integration
		1962	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1963	readable => \&IO::AIO::poll_cb);
		1964
		1965	# Danga::Socket integration
		1966	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1967	\&IO::AIO::poll_cb);
		1968
1191	=head2 FORK BEHAVIOUR	1969	=head2 FORK BEHAVIOUR
1192		1970
1193	This module should do "the right thing" when the process using it forks:	1971	Usage of pthreads in a program changes the semantics of fork
		1972	considerably. Specifically, only async-safe functions can be called after
		1973	fork. Perl doesn't know about this, so in general, you cannot call fork
		1974	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		1975	pthreads, so this applies, but many other extensions and (for inexplicable
		1976	reasons) perl itself often is linked against pthreads, so this limitation
		1977	applies to quite a lot of perls.
1194		1978
1195	Before the fork, IO::AIO enters a quiescent state where no requests	1979	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1196	can be added in other threads and no results will be processed. After	1980	only works in the process that loaded it. Forking is fully supported, but
1197	the fork the parent simply leaves the quiescent state and continues	1981	using IO::AIO in the child is not.
1198	request/result processing, while the child frees the request/result queue
1199	(so that the requests started before the fork will only be handled in the
1200	parent). Threads will be started on demand until the limit set in the
1201	parent process has been reached again.
1202		1982
1203	In short: the parent will, after a short pause, continue as if fork had	1983	You might get around by not I<using> IO::AIO before (or after)
1204	not been called, while the child will act as if IO::AIO has not been used	1984	forking. You could also try to call the L<IO::AIO::reinit> function in the
1205	yet.	1985	child:
		1986
		1987	=over 4
		1988
		1989	=item IO::AIO::reinit
		1990
		1991	Abandons all current requests and I/O threads and simply reinitialises all
		1992	data structures. This is not an operation supported by any standards, but
		1993	happens to work on GNU/Linux and some newer BSD systems.
		1994
		1995	The only reasonable use for this function is to call it after forking, if
		1996	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		1997	the process will result in undefined behaviour. Calling it at any time
		1998	will also result in any undefined (by POSIX) behaviour.
		1999
		2000	=back
1206		2001
1207	=head2 MEMORY USAGE	2002	=head2 MEMORY USAGE
1208		2003
1209	Per-request usage:	2004	Per-request usage:
1210		2005
…		…
1212	bytes of memory. In addition, stat requests need a stat buffer (possibly	2007	bytes of memory. In addition, stat requests need a stat buffer (possibly
1213	a few hundred bytes), readdir requires a result buffer and so on. Perl	2008	a few hundred bytes), readdir requires a result buffer and so on. Perl
1214	scalars and other data passed into aio requests will also be locked and	2009	scalars and other data passed into aio requests will also be locked and
1215	will consume memory till the request has entered the done state.	2010	will consume memory till the request has entered the done state.
1216		2011
1217	This is now awfully much, so queuing lots of requests is not usually a	2012	This is not awfully much, so queuing lots of requests is not usually a
1218	problem.	2013	problem.
1219		2014
1220	Per-thread usage:	2015	Per-thread usage:
1221		2016
1222	In the execution phase, some aio requests require more memory for	2017	In the execution phase, some aio requests require more memory for
…		…
1227		2022
1228	Known bugs will be fixed in the next release.	2023	Known bugs will be fixed in the next release.
1229		2024
1230	=head1 SEE ALSO	2025	=head1 SEE ALSO
1231		2026
1232	L<Coro::AIO>.	2027	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		2028	more natural syntax.
1233		2029
1234	=head1 AUTHOR	2030	=head1 AUTHOR
1235		2031
1236	Marc Lehmann <schmorp@schmorp.de>	2032	Marc Lehmann <schmorp@schmorp.de>
1237	http://home.schmorp.de/	2033	http://home.schmorp.de/

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