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Revision 1.105 by root, Sun Mar 25 00:20:27 2007 UTC vs.
Revision 1.213 by root, Thu Sep 29 23:06:23 2011 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 = '2.33';	173	our $VERSION = '4.0';
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_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
		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
200	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir);	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
		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_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		215	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		216	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		217	aio_readahead $fh,$offset,$length, $callback->($retval)
		218	aio_stat $fh_or_path, $callback->($status)
		219	aio_lstat $fh, $callback->($status)
		220	aio_statvfs $fh_or_path, $callback->($statvfs)
		221	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		222	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		223	aio_truncate $fh_or_path, $offset, $callback->($status)
		224	aio_chmod $fh_or_path, $mode, $callback->($status)
		225	aio_unlink $pathname, $callback->($status)
		226	aio_mknod $pathname, $mode, $dev, $callback->($status)
		227	aio_link $srcpath, $dstpath, $callback->($status)
		228	aio_symlink $srcpath, $dstpath, $callback->($status)
		229	aio_readlink $pathname, $callback->($link)
		230	aio_realpath $pathname, $callback->($link)
		231	aio_rename $srcpath, $dstpath, $callback->($status)
		232	aio_mkdir $pathname, $mode, $callback->($status)
		233	aio_rmdir $pathname, $callback->($status)
		234	aio_readdir $pathname, $callback->($entries)
		235	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		236	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		237	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		238	aio_load $pathname, $data, $callback->($status)
		239	aio_copy $srcpath, $dstpath, $callback->($status)
		240	aio_move $srcpath, $dstpath, $callback->($status)
		241	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		242	aio_rmtree $pathname, $callback->($status)
		243	aio_sync $callback->($status)
		244	aio_syncfs $fh, $callback->($status)
		245	aio_fsync $fh, $callback->($status)
		246	aio_fdatasync $fh, $callback->($status)
		247	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		248	aio_pathsync $pathname, $callback->($status)
		249	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		250	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		251	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		252	aio_mlockall $flags, $callback->($status)
		253	aio_group $callback->(...)
		254	aio_nop $callback->()
		255
		256	$prev_pri = aioreq_pri [$pri]
		257	aioreq_nice $pri_adjust
		258
		259	IO::AIO::poll_wait
		260	IO::AIO::poll_cb
		261	IO::AIO::poll
		262	IO::AIO::flush
		263	IO::AIO::max_poll_reqs $nreqs
		264	IO::AIO::max_poll_time $seconds
		265	IO::AIO::min_parallel $nthreads
		266	IO::AIO::max_parallel $nthreads
		267	IO::AIO::max_idle $nthreads
		268	IO::AIO::idle_timeout $seconds
		269	IO::AIO::max_outstanding $maxreqs
		270	IO::AIO::nreqs
		271	IO::AIO::nready
		272	IO::AIO::npending
		273
		274	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		275	IO::AIO::fadvise $fh, $offset, $len, $advice
		276	IO::AIO::madvise $scalar, $offset, $length, $advice
		277	IO::AIO::mprotect $scalar, $offset, $length, $protect
		278	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		279	IO::AIO::munlockall
		280
215	=head2 AIO REQUEST FUNCTIONS	281	=head2 AIO REQUEST FUNCTIONS
216		282
217	All the C<aio_*> calls are more or less thin wrappers around the syscall	283	All the C<aio_*> calls are more or less thin wrappers around the syscall
218	with the same name (sans C<aio_>). The arguments are similar or identical,	284	with the same name (sans C<aio_>). The arguments are similar or identical,
219	and they all accept an additional (and optional) C<$callback> argument	285	and they all accept an additional (and optional) C<$callback> argument
220	which must be a code reference. This code reference will get called with	286	which must be a code reference. This code reference will be called after
221	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	287	the syscall has been executed in an asynchronous fashion. The results
222	perl, which usually delivers "false") as it's sole argument when the given	288	of the request will be passed as arguments to the callback (and, if an
223	syscall has been executed asynchronously.	289	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		290	most syscalls return C<-1> on error, unlike perl, which usually delivers
		291	"false").
		292
		293	Some requests (such as C<aio_readdir>) pass the actual results and
		294	communicate failures by passing C<undef>.
224		295
225	All functions expecting a filehandle keep a copy of the filehandle	296	All functions expecting a filehandle keep a copy of the filehandle
226	internally until the request has finished.	297	internally until the request has finished.
227		298
228	All functions return request objects of type L<IO::AIO::REQ> that allow	299	All functions return request objects of type L<IO::AIO::REQ> that allow
229	further manipulation of those requests while they are in-flight.	300	further manipulation of those requests while they are in-flight.
230		301
231	The pathnames you pass to these routines I<must> be absolute and	302	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	303	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	304	current working directory could have changed. Alternatively, you can
234	changed. Alternatively, you can make sure that you never change the	305	make sure that you never change the current working directory anywhere
235	current working directory anywhere in the program and then use relative	306	in the program and then use relative paths. You can also take advantage
236	paths.	307	of IO::AIOs working directory abstraction, that lets you specify paths
		308	relative to some previously-opened "working directory object" - see the
		309	description of the C<IO::AIO::WD> class later in this document.
237		310
238	To encode pathnames as octets, either make sure you either: a) always pass	311	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	312	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	313	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	314	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)	315	effect in the user environment, d) use Glib::filename_from_unicode on
243	use something else to ensure your scalar has the correct contents.	316	unicode filenames or e) use something else to ensure your scalar has the
		317	correct contents.
244		318
245	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	319	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
246	handles correctly wether it is set or not.	320	handles correctly whether it is set or not.
247		321
248	=over 4	322	=over 4
249		323
250	=item $prev_pri = aioreq_pri [$pri]	324	=item $prev_pri = aioreq_pri [$pri]
251		325
…		…
271	aio_read $_[0], ..., sub {	345	aio_read $_[0], ..., sub {
272	...	346	...
273	};	347	};
274	};	348	};
275		349
		350
276	=item aioreq_nice $pri_adjust	351	=item aioreq_nice $pri_adjust
277		352
278	Similar to C<aioreq_pri>, but subtracts the given value from the current	353	Similar to C<aioreq_pri>, but subtracts the given value from the current
279	priority, so the effect is cumulative.	354	priority, so the effect is cumulative.
		355
280		356
281	=item aio_open $pathname, $flags, $mode, $callback->($fh)	357	=item aio_open $pathname, $flags, $mode, $callback->($fh)
282		358
283	Asynchronously open or create a file and call the callback with a newly	359	Asynchronously open or create a file and call the callback with a newly
284	created filehandle for the file.	360	created filehandle for the file.
…		…
296	by the umask in effect then the request is being executed, so better never	372	by the umask in effect then the request is being executed, so better never
297	change the umask.	373	change the umask.
298		374
299	Example:	375	Example:
300		376
301	aio_open "/etc/passwd", O_RDONLY, 0, sub {	377	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
302	if ($_[0]) {	378	if ($_[0]) {
303	print "open successful, fh is $_[0]\n";	379	print "open successful, fh is $_[0]\n";
304	...	380	...
305	} else {	381	} else {
306	die "open failed: $!\n";	382	die "open failed: $!\n";
307	}	383	}
308	};	384	};
309		385
		386	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		387	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		388	following POSIX and non-POSIX constants are available (missing ones on
		389	your system are, as usual, C<0>):
		390
		391	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		392	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		393	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		394
		395
310	=item aio_close $fh, $callback->($status)	396	=item aio_close $fh, $callback->($status)
311		397
312	Asynchronously close a file and call the callback with the result	398	Asynchronously close a file and call the callback with the result
313	code. I<WARNING:> although accepted, you should not pass in a perl	399	code.
314	filehandle here, as perl will likely close the file descriptor another
315	time when the filehandle is destroyed. Normally, you can safely call perls
316	C<close> or just let filehandles go out of scope.
317		400
318	This is supposed to be a bug in the API, so that might change. It's	401	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
319	therefore best to avoid this function.	402	closing the file descriptor associated with the filehandle itself.
		403
		404	Therefore, C<aio_close> will not close the filehandle - instead it will
		405	use dup2 to overwrite the file descriptor with the write-end of a pipe
		406	(the pipe fd will be created on demand and will be cached).
		407
		408	Or in other words: the file descriptor will be closed, but it will not be
		409	free for reuse until the perl filehandle is closed.
		410
		411	=cut
320		412
321	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	413	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
322		414
323	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	415	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
324		416
325	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	417	Reads or writes C<$length> bytes from or to the specified C<$fh> and
326	into the scalar given by C<data> and offset C<dataoffset> and calls the	418	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
327	callback without the actual number of bytes read (or -1 on error, just	419	and calls the callback without the actual number of bytes read (or -1 on
328	like the syscall).	420	error, just like the syscall).
		421
		422	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		423	offset plus the actual number of bytes read.
		424
		425	If C<$offset> is undefined, then the current file descriptor offset will
		426	be used (and updated), otherwise the file descriptor offset will not be
		427	changed by these calls.
		428
		429	If C<$length> is undefined in C<aio_write>, use the remaining length of
		430	C<$data>.
		431
		432	If C<$dataoffset> is less than zero, it will be counted from the end of
		433	C<$data>.
329		434
330	The C<$data> scalar I<MUST NOT> be modified in any way while the request	435	The C<$data> scalar I<MUST NOT> be modified in any way while the request
331	is outstanding. Modifying it can result in segfaults or WW3 (if the	436	is outstanding. Modifying it can result in segfaults or World War III (if
332	necessary/optional hardware is installed).	437	the necessary/optional hardware is installed).
333		438
334	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	439	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
335	offset C<0> within the scalar:	440	offset C<0> within the scalar:
336		441
337	aio_read $fh, 7, 15, $buffer, 0, sub {	442	aio_read $fh, 7, 15, $buffer, 0, sub {
338	$_[0] > 0 or die "read error: $!";	443	$_[0] > 0 or die "read error: $!";
339	print "read $_[0] bytes: <$buffer>\n";	444	print "read $_[0] bytes: <$buffer>\n";
340	};	445	};
341		446
		447
342	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	448	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
343		449
344	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	450	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
345	reading at byte offset C<$in_offset>, and starts writing at the current	451	reading at byte offset C<$in_offset>, and starts writing at the current
346	file offset of C<$out_fh>. Because of that, it is not safe to issue more	452	file offset of C<$out_fh>. Because of that, it is not safe to issue more
347	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	453	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
348	other.	454	other. The same C<$in_fh> works fine though, as this function does not
		455	move or use the file offset of C<$in_fh>.
349		456
		457	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		458	are written, and there is no way to find out how many more bytes have been
		459	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		460	number of bytes written to C<$out_fh>. Only if the result value equals
		461	C<$length> one can assume that C<$length> bytes have been read.
		462
		463	Unlike with other C<aio_> functions, it makes a lot of sense to use
		464	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		465	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		466	the socket I/O will be non-blocking. Note, however, that you can run
		467	into a trap where C<aio_sendfile> reads some data with readahead, then
		468	fails to write all data, and when the socket is ready the next time, the
		469	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		470	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		471	resource usage.
		472
350	This call tries to make use of a native C<sendfile> syscall to provide	473	This call tries to make use of a native C<sendfile>-like syscall to
351	zero-copy operation. For this to work, C<$out_fh> should refer to a	474	provide zero-copy operation. For this to work, C<$out_fh> should refer to
352	socket, and C<$in_fh> should refer to mmap'able file.	475	a socket, and C<$in_fh> should refer to an mmap'able file.
353		476
354	If the native sendfile call fails or is not implemented, it will be	477	If a native sendfile cannot be found or it fails with C<ENOSYS>,
355	emulated, so you can call C<aio_sendfile> on any type of filehandle	478	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		479	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
356	regardless of the limitations of the operating system.	480	type of filehandle regardless of the limitations of the operating system.
357		481
358	Please note, however, that C<aio_sendfile> can read more bytes from	482	As native sendfile syscalls (as practically any non-POSIX interface hacked
359	C<$in_fh> than are written, and there is no way to find out how many	483	together in a hurry to improve benchmark numbers) tend to be rather buggy
360	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	484	on many systems, this implementation tries to work around some known bugs
361	provides the number of bytes written to C<$out_fh>. Only if the result	485	in Linux and FreeBSD kernels (probably others, too), but that might fail,
362	value equals C<$length> one can assume that C<$length> bytes have been	486	so you really really should check the return value of C<aio_sendfile> -
363	read.	487	fewre bytes than expected might have been transferred.
		488
364		489
365	=item aio_readahead $fh,$offset,$length, $callback->($retval)	490	=item aio_readahead $fh,$offset,$length, $callback->($retval)
366		491
367	C<aio_readahead> populates the page cache with data from a file so that	492	C<aio_readahead> populates the page cache with data from a file so that
368	subsequent reads from that file will not block on disk I/O. The C<$offset>	493	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
374	file. The current file offset of the file is left unchanged.	499	file. The current file offset of the file is left unchanged.
375		500
376	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	501	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
377	emulated by simply reading the data, which would have a similar effect.	502	emulated by simply reading the data, which would have a similar effect.
378		503
		504
379	=item aio_stat $fh_or_path, $callback->($status)	505	=item aio_stat $fh_or_path, $callback->($status)
380		506
381	=item aio_lstat $fh, $callback->($status)	507	=item aio_lstat $fh, $callback->($status)
382		508
383	Works like perl's C<stat> or C<lstat> in void context. The callback will	509	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
388	for an explanation.	514	for an explanation.
389		515
390	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	516	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
391	error when stat'ing a large file, the results will be silently truncated	517	error when stat'ing a large file, the results will be silently truncated
392	unless perl itself is compiled with large file support.	518	unless perl itself is compiled with large file support.
		519
		520	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		521	following constants and functions (if not implemented, the constants will
		522	be C<0> and the functions will either C<croak> or fall back on traditional
		523	behaviour).
		524
		525	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		526	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		527	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
393		528
394	Example: Print the length of F</etc/passwd>:	529	Example: Print the length of F</etc/passwd>:
395		530
396	aio_stat "/etc/passwd", sub {	531	aio_stat "/etc/passwd", sub {
397	$_[0] and die "stat failed: $!";	532	$_[0] and die "stat failed: $!";
398	print "size is ", -s _, "\n";	533	print "size is ", -s _, "\n";
399	};	534	};
400		535
		536
		537	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		538
		539	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		540	whether a file handle or path was passed.
		541
		542	On success, the callback is passed a hash reference with the following
		543	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		544	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		545	is passed.
		546
		547	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		548	C<ST_NOSUID>.
		549
		550	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		551	their correct value when available, or to C<0> on systems that do
		552	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		553	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		554	C<ST_NODIRATIME> and C<ST_RELATIME>.
		555
		556	Example: stat C</wd> and dump out the data if successful.
		557
		558	aio_statvfs "/wd", sub {
		559	my $f = $_[0]
		560	or die "statvfs: $!";
		561
		562	use Data::Dumper;
		563	say Dumper $f;
		564	};
		565
		566	# result:
		567	{
		568	bsize => 1024,
		569	bfree => 4333064312,
		570	blocks => 10253828096,
		571	files => 2050765568,
		572	flag => 4096,
		573	favail => 2042092649,
		574	bavail => 4333064312,
		575	ffree => 2042092649,
		576	namemax => 255,
		577	frsize => 1024,
		578	fsid => 1810
		579	}
		580
		581
		582	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		583
		584	Works like perl's C<utime> function (including the special case of $atime
		585	and $mtime being undef). Fractional times are supported if the underlying
		586	syscalls support them.
		587
		588	When called with a pathname, uses utimes(2) if available, otherwise
		589	utime(2). If called on a file descriptor, uses futimes(2) if available,
		590	otherwise returns ENOSYS, so this is not portable.
		591
		592	Examples:
		593
		594	# set atime and mtime to current time (basically touch(1)):
		595	aio_utime "path", undef, undef;
		596	# set atime to current time and mtime to beginning of the epoch:
		597	aio_utime "path", time, undef; # undef==0
		598
		599
		600	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		601
		602	Works like perl's C<chown> function, except that C<undef> for either $uid
		603	or $gid is being interpreted as "do not change" (but -1 can also be used).
		604
		605	Examples:
		606
		607	# same as "chown root path" in the shell:
		608	aio_chown "path", 0, -1;
		609	# same as above:
		610	aio_chown "path", 0, undef;
		611
		612
		613	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		614
		615	Works like truncate(2) or ftruncate(2).
		616
		617
		618	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		619
		620	Works like perl's C<chmod> function.
		621
		622
401	=item aio_unlink $pathname, $callback->($status)	623	=item aio_unlink $pathname, $callback->($status)
402		624
403	Asynchronously unlink (delete) a file and call the callback with the	625	Asynchronously unlink (delete) a file and call the callback with the
404	result code.	626	result code.
405		627
		628
406	=item aio_mknod $path, $mode, $dev, $callback->($status)	629	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
407		630
408	[EXPERIMENTAL]	631	[EXPERIMENTAL]
409		632
410	Asynchronously create a device node (or fifo). See mknod(2).	633	Asynchronously create a device node (or fifo). See mknod(2).
411		634
412	The only (POSIX-) portable way of calling this function is:	635	The only (POSIX-) portable way of calling this function is:
413		636
414	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	637	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		638
		639	See C<aio_stat> for info about some potentially helpful extra constants
		640	and functions.
415		641
416	=item aio_link $srcpath, $dstpath, $callback->($status)	642	=item aio_link $srcpath, $dstpath, $callback->($status)
417		643
418	Asynchronously create a new link to the existing object at C<$srcpath> at	644	Asynchronously create a new link to the existing object at C<$srcpath> at
419	the path C<$dstpath> and call the callback with the result code.	645	the path C<$dstpath> and call the callback with the result code.
420		646
		647
421	=item aio_symlink $srcpath, $dstpath, $callback->($status)	648	=item aio_symlink $srcpath, $dstpath, $callback->($status)
422		649
423	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	650	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
424	the path C<$dstpath> and call the callback with the result code.	651	the path C<$dstpath> and call the callback with the result code.
425		652
		653
426	=item aio_readlink $path, $callback->($link)	654	=item aio_readlink $pathname, $callback->($link)
427		655
428	Asynchronously read the symlink specified by C<$path> and pass it to	656	Asynchronously read the symlink specified by C<$path> and pass it to
429	the callback. If an error occurs, nothing or undef gets passed to the	657	the callback. If an error occurs, nothing or undef gets passed to the
430	callback.	658	callback.
431		659
		660
		661	=item aio_realpath $pathname, $callback->($path)
		662
		663	Asynchronously make the path absolute and resolve any symlinks in
		664	C<$path>. The resulting path only consists of directories (Same as
		665	L<Cwd::realpath>).
		666
		667	This request can be used to get the absolute path of the current working
		668	directory by passing it a path of F<.> (a single dot).
		669
		670
432	=item aio_rename $srcpath, $dstpath, $callback->($status)	671	=item aio_rename $srcpath, $dstpath, $callback->($status)
433		672
434	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	673	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
435	rename(2) and call the callback with the result code.	674	rename(2) and call the callback with the result code.
		675
436		676
437	=item aio_mkdir $pathname, $mode, $callback->($status)	677	=item aio_mkdir $pathname, $mode, $callback->($status)
438		678
439	Asynchronously mkdir (create) a directory and call the callback with	679	Asynchronously mkdir (create) a directory and call the callback with
440	the result code. C<$mode> will be modified by the umask at the time the	680	the result code. C<$mode> will be modified by the umask at the time the
441	request is executed, so do not change your umask.	681	request is executed, so do not change your umask.
442		682
		683
443	=item aio_rmdir $pathname, $callback->($status)	684	=item aio_rmdir $pathname, $callback->($status)
444		685
445	Asynchronously rmdir (delete) a directory and call the callback with the	686	Asynchronously rmdir (delete) a directory and call the callback with the
446	result code.	687	result code.
		688
447		689
448	=item aio_readdir $pathname, $callback->($entries)	690	=item aio_readdir $pathname, $callback->($entries)
449		691
450	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	692	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
451	directory (i.e. opendir + readdir + closedir). The entries will not be	693	directory (i.e. opendir + readdir + closedir). The entries will not be
452	sorted, and will B<NOT> include the C<.> and C<..> entries.	694	sorted, and will B<NOT> include the C<.> and C<..> entries.
453		695
454	The callback a single argument which is either C<undef> or an array-ref	696	The callback is passed a single argument which is either C<undef> or an
455	with the filenames.	697	array-ref with the filenames.
456		698
		699
		700	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		701
		702	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
		703	tune behaviour and output format. In case of an error, C<$entries> will be
		704	C<undef>.
		705
		706	The flags are a combination of the following constants, ORed together (the
		707	flags will also be passed to the callback, possibly modified):
		708
		709	=over 4
		710
		711	=item IO::AIO::READDIR_DENTS
		712
		713	When this flag is off, then the callback gets an arrayref consisting of
		714	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		715	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		716	entry in more detail.
		717
		718	C<$name> is the name of the entry.
		719
		720	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		721
		722	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		723	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		724	C<IO::AIO::DT_WHT>.
		725
		726	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		727	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		728	scalars are read-only: you can not modify them.
		729
		730	C<$inode> is the inode number (which might not be exact on systems with 64
		731	bit inode numbers and 32 bit perls). This field has unspecified content on
		732	systems that do not deliver the inode information.
		733
		734	=item IO::AIO::READDIR_DIRS_FIRST
		735
		736	When this flag is set, then the names will be returned in an order where
		737	likely directories come first, in optimal stat order. This is useful when
		738	you need to quickly find directories, or you want to find all directories
		739	while avoiding to stat() each entry.
		740
		741	If the system returns type information in readdir, then this is used
		742	to find directories directly. Otherwise, likely directories are names
		743	beginning with ".", or otherwise names with no dots, of which names with
		744	short names are tried first.
		745
		746	=item IO::AIO::READDIR_STAT_ORDER
		747
		748	When this flag is set, then the names will be returned in an order
		749	suitable for stat()'ing each one. That is, when you plan to stat()
		750	all files in the given directory, then the returned order will likely
		751	be fastest.
		752
		753	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		754	the likely dirs come first, resulting in a less optimal stat order.
		755
		756	=item IO::AIO::READDIR_FOUND_UNKNOWN
		757
		758	This flag should not be set when calling C<aio_readdirx>. Instead, it
		759	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		760	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
		761	C<$type>'s are known, which can be used to speed up some algorithms.
		762
		763	=back
		764
		765
457	=item aio_load $path, $data, $callback->($status)	766	=item aio_load $pathname, $data, $callback->($status)
458		767
459	This is a composite request that tries to fully load the given file into	768	This is a composite request that tries to fully load the given file into
460	memory. Status is the same as with aio_read.	769	memory. Status is the same as with aio_read.
461		770
462	=cut	771	=cut
463		772
464	sub aio_load($$;$) {	773	sub aio_load($$;$) {
465	aio_block {
466	my ($path, undef, $cb) = @_;	774	my ($path, undef, $cb) = @_;
467	my $data = \$_[1];	775	my $data = \$_[1];
468		776
469	my $pri = aioreq_pri;	777	my $pri = aioreq_pri;
470	my $grp = aio_group $cb;	778	my $grp = aio_group $cb;
		779
		780	aioreq_pri $pri;
		781	add $grp aio_open $path, O_RDONLY, 0, sub {
		782	my $fh = shift
		783	or return $grp->result (-1);
471		784
472	aioreq_pri $pri;	785	aioreq_pri $pri;
473	add $grp aio_open $path, O_RDONLY, 0, sub {
474	my $fh = shift
475	or return $grp->result (-1);
476
477	aioreq_pri $pri;
478	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {	786	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
479	$grp->result ($_[0]);	787	$grp->result ($_[0]);
480	};
481	};	788	};
482
483	$grp
484	}	789	};
		790
		791	$grp
485	}	792	}
486		793
487	=item aio_copy $srcpath, $dstpath, $callback->($status)	794	=item aio_copy $srcpath, $dstpath, $callback->($status)
488		795
489	Try to copy the I<file> (directories not supported as either source or	796	Try to copy the I<file> (directories not supported as either source or
490	destination) from C<$srcpath> to C<$dstpath> and call the callback with	797	destination) from C<$srcpath> to C<$dstpath> and call the callback with
491	the C<0> (error) or C<-1> ok.	798	a status of C<0> (ok) or C<-1> (error, see C<$!>).
492		799
493	This is a composite request that it creates the destination file with	800	This is a composite request that creates the destination file with
494	mode 0200 and copies the contents of the source file into it using	801	mode 0200 and copies the contents of the source file into it using
495	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	802	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
496	uid/gid, in that order.	803	uid/gid, in that order.
497		804
498	If an error occurs, the partial destination file will be unlinked, if	805	If an error occurs, the partial destination file will be unlinked, if
…		…
500	errors are being ignored.	807	errors are being ignored.
501		808
502	=cut	809	=cut
503		810
504	sub aio_copy($$;$) {	811	sub aio_copy($$;$) {
505	aio_block {
506	my ($src, $dst, $cb) = @_;	812	my ($src, $dst, $cb) = @_;
507		813
508	my $pri = aioreq_pri;	814	my $pri = aioreq_pri;
509	my $grp = aio_group $cb;	815	my $grp = aio_group $cb;
510		816
511	aioreq_pri $pri;	817	aioreq_pri $pri;
512	add $grp aio_open $src, O_RDONLY, 0, sub {	818	add $grp aio_open $src, O_RDONLY, 0, sub {
513	if (my $src_fh = $_[0]) {	819	if (my $src_fh = $_[0]) {
514	my @stat = stat $src_fh;	820	my @stat = stat $src_fh; # hmm, might block over nfs?
515		821
516	aioreq_pri $pri;	822	aioreq_pri $pri;
517	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	823	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
518	if (my $dst_fh = $_[0]) {	824	if (my $dst_fh = $_[0]) {
519	aioreq_pri $pri;	825	aioreq_pri $pri;
520	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	826	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
521	if ($_[0] == $stat[7]) {	827	if ($_[0] == $stat[7]) {
522	$grp->result (0);	828	$grp->result (0);
523	close $src_fh;	829	close $src_fh;
524		830
525	# those should not normally block. should. should.
526	utime $stat[8], $stat[9], $dst;
527	chmod $stat[2] & 07777, $dst_fh;
528	chown $stat[4], $stat[5], $dst_fh;
529	close $dst_fh;
530	} else {	831	my $ch = sub {
531	$grp->result (-1);
532	close $src_fh;
533	close $dst_fh;
534
535	aioreq $pri;	832	aioreq_pri $pri;
		833	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		834	aioreq_pri $pri;
		835	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		836	aioreq_pri $pri;
536	add $grp aio_unlink $dst;	837	add $grp aio_close $dst_fh;
		838	}
		839	};
537	}	840	};
		841
		842	aioreq_pri $pri;
		843	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		844	if ($_[0] < 0 && $! == ENOSYS) {
		845	aioreq_pri $pri;
		846	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		847	} else {
		848	$ch->();
		849	}
		850	};
		851	} else {
		852	$grp->result (-1);
		853	close $src_fh;
		854	close $dst_fh;
		855
		856	aioreq $pri;
		857	add $grp aio_unlink $dst;
538	};	858	}
539	} else {
540	$grp->result (-1);
541	}	859	};
		860	} else {
		861	$grp->result (-1);
542	},	862	}
543
544	} else {
545	$grp->result (-1);
546	}	863	},
		864
		865	} else {
		866	$grp->result (-1);
547	};	867	}
548
549	$grp
550	}	868	};
		869
		870	$grp
551	}	871	}
552		872
553	=item aio_move $srcpath, $dstpath, $callback->($status)	873	=item aio_move $srcpath, $dstpath, $callback->($status)
554		874
555	Try to move the I<file> (directories not supported as either source or	875	Try to move the I<file> (directories not supported as either source or
556	destination) from C<$srcpath> to C<$dstpath> and call the callback with	876	destination) from C<$srcpath> to C<$dstpath> and call the callback with
557	the C<0> (error) or C<-1> ok.	877	a status of C<0> (ok) or C<-1> (error, see C<$!>).
558		878
559	This is a composite request that tries to rename(2) the file first. If	879	This is a composite request that tries to rename(2) the file first; if
560	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if	880	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
561	that is successful, unlinking the C<$srcpath>.	881	that is successful, unlinks the C<$srcpath>.
562		882
563	=cut	883	=cut
564		884
565	sub aio_move($$;$) {	885	sub aio_move($$;$) {
566	aio_block {
567	my ($src, $dst, $cb) = @_;	886	my ($src, $dst, $cb) = @_;
568		887
569	my $pri = aioreq_pri;	888	my $pri = aioreq_pri;
570	my $grp = aio_group $cb;	889	my $grp = aio_group $cb;
571		890
572	aioreq_pri $pri;	891	aioreq_pri $pri;
573	add $grp aio_rename $src, $dst, sub {	892	add $grp aio_rename $src, $dst, sub {
574	if ($_[0] && $! == EXDEV) {	893	if ($_[0] && $! == EXDEV) {
575	aioreq_pri $pri;	894	aioreq_pri $pri;
576	add $grp aio_copy $src, $dst, sub {	895	add $grp aio_copy $src, $dst, sub {
577	$grp->result ($_[0]);
578
579	if (!$_[0]) {
580	aioreq_pri $pri;
581	add $grp aio_unlink $src;
582	}
583	};
584	} else {
585	$grp->result ($_[0]);	896	$grp->result ($_[0]);
		897
		898	unless ($_[0]) {
		899	aioreq_pri $pri;
		900	add $grp aio_unlink $src;
		901	}
586	}	902	};
		903	} else {
		904	$grp->result ($_[0]);
587	};	905	}
588
589	$grp
590	}	906	};
		907
		908	$grp
591	}	909	}
592		910
593	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	911	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
594		912
595	Scans a directory (similar to C<aio_readdir>) but additionally tries to	913	Scans a directory (similar to C<aio_readdir>) but additionally tries to
596	efficiently separate the entries of directory C<$path> into two sets of	914	efficiently separate the entries of directory C<$path> into two sets of
597	names, directories you can recurse into (directories), and ones you cannot	915	names, directories you can recurse into (directories), and ones you cannot
598	recurse into (everything else, including symlinks to directories).	916	recurse into (everything else, including symlinks to directories).
…		…
615		933
616	Implementation notes.	934	Implementation notes.
617		935
618	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	936	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
619		937
		938	If readdir returns file type information, then this is used directly to
		939	find directories.
		940
620	After reading the directory, the modification time, size etc. of the	941	Otherwise, after reading the directory, the modification time, size etc.
621	directory before and after the readdir is checked, and if they match (and	942	of the directory before and after the readdir is checked, and if they
622	isn't the current time), the link count will be used to decide how many	943	match (and isn't the current time), the link count will be used to decide
623	entries are directories (if >= 2). Otherwise, no knowledge of the number	944	how many entries are directories (if >= 2). Otherwise, no knowledge of the
624	of subdirectories will be assumed.	945	number of subdirectories will be assumed.
625		946
626	Then entries will be sorted into likely directories (everything without	947	Then entries will be sorted into likely directories a non-initial dot
627	a non-initial dot currently) and likely non-directories (everything	948	currently) and likely non-directories (see C<aio_readdirx>). Then every
628	else). Then every entry plus an appended C</.> will be C<stat>'ed,	949	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
629	likely directories first. If that succeeds, it assumes that the entry	950	in order of their inode numbers. If that succeeds, it assumes that the
630	is a directory or a symlink to directory (which will be checked	951	entry is a directory or a symlink to directory (which will be checked
631	seperately). This is often faster than stat'ing the entry itself because	952	separately). This is often faster than stat'ing the entry itself because
632	filesystems might detect the type of the entry without reading the inode	953	filesystems might detect the type of the entry without reading the inode
633	data (e.g. ext2fs filetype feature).	954	data (e.g. ext2fs filetype feature), even on systems that cannot return
		955	the filetype information on readdir.
634		956
635	If the known number of directories (link count - 2) has been reached, the	957	If the known number of directories (link count - 2) has been reached, the
636	rest of the entries is assumed to be non-directories.	958	rest of the entries is assumed to be non-directories.
637		959
638	This only works with certainty on POSIX (= UNIX) filesystems, which	960	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
643	directory counting heuristic.	965	directory counting heuristic.
644		966
645	=cut	967	=cut
646		968
647	sub aio_scandir($$;$) {	969	sub aio_scandir($$;$) {
648	aio_block {
649	my ($path, $maxreq, $cb) = @_;	970	my ($path, $maxreq, $cb) = @_;
650		971
651	my $pri = aioreq_pri;	972	my $pri = aioreq_pri;
652		973
653	my $grp = aio_group $cb;	974	my $grp = aio_group $cb;
654		975
655	$maxreq = 4 if $maxreq <= 0;	976	$maxreq = 4 if $maxreq <= 0;
		977
		978	# get a wd object
		979	aioreq_pri $pri;
		980	add $grp aio_wd $path, sub {
		981	$_[0]
		982	or return $grp->result ();
		983
		984	my $wd = [shift, "."];
656		985
657	# stat once	986	# stat once
658	aioreq_pri $pri;	987	aioreq_pri $pri;
659	add $grp aio_stat $path, sub {	988	add $grp aio_stat $wd, sub {
660	return $grp->result () if $_[0];	989	return $grp->result () if $_[0];
661	my $now = time;	990	my $now = time;
662	my $hash1 = join ":", (stat _)[0,1,3,7,9];	991	my $hash1 = join ":", (stat _)[0,1,3,7,9];
663		992
664	# read the directory entries	993	# read the directory entries
665	aioreq_pri $pri;	994	aioreq_pri $pri;
666	add $grp aio_readdir $path, sub {	995	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
667	my $entries = shift	996	my $entries = shift
668	or return $grp->result ();	997	or return $grp->result ();
669		998
670	# stat the dir another time	999	# stat the dir another time
671	aioreq_pri $pri;	1000	aioreq_pri $pri;
672	add $grp aio_stat $path, sub {	1001	add $grp aio_stat $wd, sub {
673	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1002	my $hash2 = join ":", (stat _)[0,1,3,7,9];
674		1003
675	my $ndirs;	1004	my $ndirs;
676		1005
677	# take the slow route if anything looks fishy	1006	# take the slow route if anything looks fishy
678	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1007	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
679	$ndirs = -1;	1008	$ndirs = -1;
680	} else {	1009	} else {
681	# if nlink == 2, we are finished	1010	# if nlink == 2, we are finished
682	# on non-posix-fs's, we rely on nlink < 2	1011	# for non-posix-fs's, we rely on nlink < 2
683	$ndirs = (stat _)[3] - 2	1012	$ndirs = (stat _)[3] - 2
684	or return $grp->result ([], $entries);	1013	or return $grp->result ([], $entries);
685	}	1014	}
686		1015
687	# sort into likely dirs and likely nondirs
688	# dirs == files without ".", short entries first
689	$entries = [map $_->[0],
690	sort { $b->[1] cmp $a->[1] }
691	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
692	@$entries];
693
694	my (@dirs, @nondirs);	1016	my (@dirs, @nondirs);
695		1017
696	my $statgrp = add $grp aio_group sub {	1018	my $statgrp = add $grp aio_group sub {
697	$grp->result (\@dirs, \@nondirs);	1019	$grp->result (\@dirs, \@nondirs);
698	};	1020	};
699		1021
700	limit $statgrp $maxreq;	1022	limit $statgrp $maxreq;
701	feed $statgrp sub {	1023	feed $statgrp sub {
702	return unless @$entries;	1024	return unless @$entries;
703	my $entry = pop @$entries;	1025	my $entry = shift @$entries;
704		1026
705	aioreq_pri $pri;	1027	aioreq_pri $pri;
		1028	$wd->[1] = "$entry/.";
706	add $statgrp aio_stat "$path/$entry/.", sub {	1029	add $statgrp aio_stat $wd, sub {
707	if ($_[0] < 0) {	1030	if ($_[0] < 0) {
708	push @nondirs, $entry;	1031	push @nondirs, $entry;
709	} else {	1032	} else {
710	# need to check for real directory	1033	# need to check for real directory
711	aioreq_pri $pri;	1034	aioreq_pri $pri;
		1035	$wd->[1] = $entry;
712	add $statgrp aio_lstat "$path/$entry", sub {	1036	add $statgrp aio_lstat $wd, sub {
713	if (-d _) {	1037	if (-d _) {
714	push @dirs, $entry;	1038	push @dirs, $entry;
715		1039
716	unless (--$ndirs) {	1040	unless (--$ndirs) {
717	push @nondirs, @$entries;	1041	push @nondirs, @$entries;
…		…
725	};	1049	};
726	};	1050	};
727	};	1051	};
728	};	1052	};
729	};	1053	};
730
731	$grp
732	}	1054	};
		1055
		1056	$grp
733	}	1057	}
734		1058
735	=item aio_rmtree $path, $callback->($status)	1059	=item aio_rmtree $pathname, $callback->($status)
736		1060
737	Delete a directory tree starting (and including) C<$path>, return the	1061	Delete a directory tree starting (and including) C<$path>, return the
738	status of the final C<rmdir> only. This is a composite request that	1062	status of the final C<rmdir> only. This is a composite request that
739	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1063	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
740	everything else.	1064	everything else.
741		1065
742	=cut	1066	=cut
743		1067
744	sub aio_rmtree;	1068	sub aio_rmtree;
745	sub aio_rmtree($;$) {	1069	sub aio_rmtree($;$) {
746	aio_block {
747	my ($path, $cb) = @_;	1070	my ($path, $cb) = @_;
748		1071
749	my $pri = aioreq_pri;	1072	my $pri = aioreq_pri;
750	my $grp = aio_group $cb;	1073	my $grp = aio_group $cb;
751		1074
752	aioreq_pri $pri;	1075	aioreq_pri $pri;
753	add $grp aio_scandir $path, 0, sub {	1076	add $grp aio_scandir $path, 0, sub {
754	my ($dirs, $nondirs) = @_;	1077	my ($dirs, $nondirs) = @_;
755		1078
756	my $dirgrp = aio_group sub {	1079	my $dirgrp = aio_group sub {
757	add $grp aio_rmdir $path, sub {	1080	add $grp aio_rmdir $path, sub {
758	$grp->result ($_[0]);	1081	$grp->result ($_[0]);
759	};
760	};	1082	};
761
762	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
763	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
764
765	add $grp $dirgrp;
766	};	1083	};
767		1084
768	$grp	1085	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1086	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1087
		1088	add $grp $dirgrp;
769	}	1089	};
		1090
		1091	$grp
770	}	1092	}
		1093
		1094	=item aio_sync $callback->($status)
		1095
		1096	Asynchronously call sync and call the callback when finished.
771		1097
772	=item aio_fsync $fh, $callback->($status)	1098	=item aio_fsync $fh, $callback->($status)
773		1099
774	Asynchronously call fsync on the given filehandle and call the callback	1100	Asynchronously call fsync on the given filehandle and call the callback
775	with the fsync result code.	1101	with the fsync result code.
…		…
779	Asynchronously call fdatasync on the given filehandle and call the	1105	Asynchronously call fdatasync on the given filehandle and call the
780	callback with the fdatasync result code.	1106	callback with the fdatasync result code.
781		1107
782	If this call isn't available because your OS lacks it or it couldn't be	1108	If this call isn't available because your OS lacks it or it couldn't be
783	detected, it will be emulated by calling C<fsync> instead.	1109	detected, it will be emulated by calling C<fsync> instead.
		1110
		1111	=item aio_syncfs $fh, $callback->($status)
		1112
		1113	Asynchronously call the syncfs syscall to sync the filesystem associated
		1114	to the given filehandle and call the callback with the syncfs result
		1115	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1116	errno to C<ENOSYS> nevertheless.
		1117
		1118	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1119
		1120	Sync the data portion of the file specified by C<$offset> and C<$length>
		1121	to disk (but NOT the metadata), by calling the Linux-specific
		1122	sync_file_range call. If sync_file_range is not available or it returns
		1123	ENOSYS, then fdatasync or fsync is being substituted.
		1124
		1125	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1126	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1127	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1128	manpage for details.
		1129
		1130	=item aio_pathsync $pathname, $callback->($status)
		1131
		1132	This request tries to open, fsync and close the given path. This is a
		1133	composite request intended to sync directories after directory operations
		1134	(E.g. rename). This might not work on all operating systems or have any
		1135	specific effect, but usually it makes sure that directory changes get
		1136	written to disc. It works for anything that can be opened for read-only,
		1137	not just directories.
		1138
		1139	Future versions of this function might fall back to other methods when
		1140	C<fsync> on the directory fails (such as calling C<sync>).
		1141
		1142	Passes C<0> when everything went ok, and C<-1> on error.
		1143
		1144	=cut
		1145
		1146	sub aio_pathsync($;$) {
		1147	my ($path, $cb) = @_;
		1148
		1149	my $pri = aioreq_pri;
		1150	my $grp = aio_group $cb;
		1151
		1152	aioreq_pri $pri;
		1153	add $grp aio_open $path, O_RDONLY, 0, sub {
		1154	my ($fh) = @_;
		1155	if ($fh) {
		1156	aioreq_pri $pri;
		1157	add $grp aio_fsync $fh, sub {
		1158	$grp->result ($_[0]);
		1159
		1160	aioreq_pri $pri;
		1161	add $grp aio_close $fh;
		1162	};
		1163	} else {
		1164	$grp->result (-1);
		1165	}
		1166	};
		1167
		1168	$grp
		1169	}
		1170
		1171	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1172
		1173	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1174	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1175	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1176	scalar must only be modified in-place while an aio operation is pending on
		1177	it).
		1178
		1179	It calls the C<msync> function of your OS, if available, with the memory
		1180	area starting at C<$offset> in the string and ending C<$length> bytes
		1181	later. If C<$length> is negative, counts from the end, and if C<$length>
		1182	is C<undef>, then it goes till the end of the string. The flags can be
		1183	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1184	C<IO::AIO::MS_SYNC>.
		1185
		1186	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1187
		1188	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1189	scalars.
		1190
		1191	It touches (reads or writes) all memory pages in the specified
		1192	range inside the scalar. All caveats and parameters are the same
		1193	as for C<aio_msync>, above, except for flags, which must be either
		1194	C<0> (which reads all pages and ensures they are instantiated) or
		1195	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1196	writing an octet from it, which dirties the page).
		1197
		1198	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1199
		1200	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1201	scalars.
		1202
		1203	It reads in all the pages of the underlying storage into memory (if any)
		1204	and locks them, so they are not getting swapped/paged out or removed.
		1205
		1206	If C<$length> is undefined, then the scalar will be locked till the end.
		1207
		1208	On systems that do not implement C<mlock>, this function returns C<-1>
		1209	and sets errno to C<ENOSYS>.
		1210
		1211	Note that the corresponding C<munlock> is synchronous and is
		1212	documented under L<MISCELLANEOUS FUNCTIONS>.
		1213
		1214	Example: open a file, mmap and mlock it - both will be undone when
		1215	C<$data> gets destroyed.
		1216
		1217	open my $fh, "<", $path or die "$path: $!";
		1218	my $data;
		1219	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1220	aio_mlock $data; # mlock in background
		1221
		1222	=item aio_mlockall $flags, $callback->($status)
		1223
		1224	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1225	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1226
		1227	On systems that do not implement C<mlockall>, this function returns C<-1>
		1228	and sets errno to C<ENOSYS>.
		1229
		1230	Note that the corresponding C<munlockall> is synchronous and is
		1231	documented under L<MISCELLANEOUS FUNCTIONS>.
		1232
		1233	Example: asynchronously lock all current and future pages into memory.
		1234
		1235	aio_mlockall IO::AIO::MCL_FUTURE;
784		1236
785	=item aio_group $callback->(...)	1237	=item aio_group $callback->(...)
786		1238
787	This is a very special aio request: Instead of doing something, it is a	1239	This is a very special aio request: Instead of doing something, it is a
788	container for other aio requests, which is useful if you want to bundle	1240	container for other aio requests, which is useful if you want to bundle
…		…
826	immense (it blocks a thread for a long time) so do not use this function	1278	immense (it blocks a thread for a long time) so do not use this function
827	except to put your application under artificial I/O pressure.	1279	except to put your application under artificial I/O pressure.
828		1280
829	=back	1281	=back
830		1282
		1283
		1284	=head2 IO::AIO::WD - multiple working directories
		1285
		1286	Your process only has one current working directory, which is used by all
		1287	threads. This makes it hard to use relative paths (some other component
		1288	could call C<chdir> at any time, and it is hard to control when the path
		1289	will be used by IO::AIO).
		1290
		1291	One solution for this is to always use absolute paths. This usually works,
		1292	but can be quite slow (the kernel has to walk the whole path on every
		1293	access), and can also be a hassle to implement.
		1294
		1295	Newer POSIX systems have a number of functions (openat, fdopendir,
		1296	futimensat and so on) that make it possible to specify working directories
		1297	per operation.
		1298
		1299	For portability, and because the clowns who "designed", or shall I write,
		1300	perpetrated this new interface were obviously half-drunk, this abstraction
		1301	cannot be perfect, though.
		1302
		1303	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1304	object. This object stores the canonicalised, absolute version of the
		1305	path, and on systems that allow it, also a directory file descriptor.
		1306
		1307	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1308	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1309	object and a pathname instead. If the pathname is absolute, the
		1310	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1311	to that IO::AIO::WD object.
		1312
		1313	For example, to get a wd object for F</etc> and then stat F<passwd>
		1314	inside, you would write:
		1315
		1316	aio_wd "/etc", sub {
		1317	my $etcdir = shift;
		1318
		1319	# although $etcdir can be undef on error, there is generally no reason
		1320	# to check for errors here, as aio_stat will fail with ENOENT
		1321	# when $etcdir is undef.
		1322
		1323	aio_stat [$etcdir, "passwd"], sub {
		1324	# yay
		1325	};
		1326	};
		1327
		1328	This shows that creating an IO::AIO::WD object is itself a potentially
		1329	blocking operation, which is why it is done asynchronously.
		1330
		1331	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1332	object and the pathname string, so you could write the following without
		1333	causing any issues due to C<$path> getting reused:
		1334
		1335	my $path = [$wd, undef];
		1336
		1337	for my $name (qw(abc def ghi)) {
		1338	$path->[1] = $name;
		1339	aio_stat $path, sub {
		1340	# ...
		1341	};
		1342	}
		1343
		1344	There are some caveats: when directories get renamed (or deleted), the
		1345	pathname string doesn't change, so will point to the new directory (or
		1346	nowhere at all), while the directory fd, if available on the system,
		1347	will still point to the original directory. Most functions accepting a
		1348	pathname will use the directory fd on newer systems, and the string on
		1349	older systems. Some functions (such as realpath) will always rely on the
		1350	string form of the pathname.
		1351
		1352	So this fucntionality is mainly useful to get some protection against
		1353	C<chdir>, to easily get an absolute path out of a relative path for future
		1354	reference, and to speed up doing many operations in the same directory
		1355	(e.g. when stat'ing all files in a directory).
		1356
		1357	The following functions implement this working directory abstraction:
		1358
		1359	=over 4
		1360
		1361	=item aio_wd $pathname, $callback->($wd)
		1362
		1363	Asynchonously canonicalise the given pathname and convert it to an
		1364	IO::AIO::WD object representing it. If possible and supported on the
		1365	system, also open a directory fd to speed up pathname resolution relative
		1366	to this working directory.
		1367
		1368	If something goes wrong, then C<undef> is passwd to the callback instead
		1369	of a working directory object and C<$!> is set appropriately. Since
		1370	passing C<undef> as working directory component of a pathname fails the
		1371	request with C<ENOENT>, there is often no need for error checking in the
		1372	C<aio_wd> callback, as future requests using the value will fail in the
		1373	expected way.
		1374
		1375	If this call isn't available because your OS lacks it or it couldn't be
		1376	detected, it will be emulated by calling C<fsync> instead.
		1377
		1378	=item IO::AIO::CWD
		1379
		1380	This is a compiletime constant (object) that represents the process
		1381	current working directory.
		1382
		1383	Specifying this object as working directory object for a pathname is as
		1384	if the pathname would be specified directly, without a directory object,
		1385	e.g., these calls are functionally identical:
		1386
		1387	aio_stat "somefile", sub { ... };
		1388	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1389
		1390	=back
		1391
		1392
831	=head2 IO::AIO::REQ CLASS	1393	=head2 IO::AIO::REQ CLASS
832		1394
833	All non-aggregate C<aio_*> functions return an object of this class when	1395	All non-aggregate C<aio_*> functions return an object of this class when
834	called in non-void context.	1396	called in non-void context.
835		1397
…		…
838	=item cancel $req	1400	=item cancel $req
839		1401
840	Cancels the request, if possible. Has the effect of skipping execution	1402	Cancels the request, if possible. Has the effect of skipping execution
841	when entering the B<execute> state and skipping calling the callback when	1403	when entering the B<execute> state and skipping calling the callback when
842	entering the the B<result> state, but will leave the request otherwise	1404	entering the the B<result> state, but will leave the request otherwise
843	untouched. That means that requests that currently execute will not be	1405	untouched (with the exception of readdir). That means that requests that
844	stopped and resources held by the request will not be freed prematurely.	1406	currently execute will not be stopped and resources held by the request
		1407	will not be freed prematurely.
845		1408
846	=item cb $req $callback->(...)	1409	=item cb $req $callback->(...)
847		1410
848	Replace (or simply set) the callback registered to the request.	1411	Replace (or simply set) the callback registered to the request.
849		1412
…		…
900	Their lifetime, simplified, looks like this: when they are empty, they	1463	Their lifetime, simplified, looks like this: when they are empty, they
901	will finish very quickly. If they contain only requests that are in the	1464	will finish very quickly. If they contain only requests that are in the
902	C<done> state, they will also finish. Otherwise they will continue to	1465	C<done> state, they will also finish. Otherwise they will continue to
903	exist.	1466	exist.
904		1467
905	That means after creating a group you have some time to add requests. And	1468	That means after creating a group you have some time to add requests
906	in the callbacks of those requests, you can add further requests to the	1469	(precisely before the callback has been invoked, which is only done within
907	group. And only when all those requests have finished will the the group	1470	the C<poll_cb>). And in the callbacks of those requests, you can add
908	itself finish.	1471	further requests to the group. And only when all those requests have
		1472	finished will the the group itself finish.
909		1473
910	=over 4	1474	=over 4
911		1475
912	=item add $grp ...	1476	=item add $grp ...
913		1477
…		…
922	=item $grp->cancel_subs	1486	=item $grp->cancel_subs
923		1487
924	Cancel all subrequests and clears any feeder, but not the group request	1488	Cancel all subrequests and clears any feeder, but not the group request
925	itself. Useful when you queued a lot of events but got a result early.	1489	itself. Useful when you queued a lot of events but got a result early.
926		1490
		1491	The group request will finish normally (you cannot add requests to the
		1492	group).
		1493
927	=item $grp->result (...)	1494	=item $grp->result (...)
928		1495
929	Set the result value(s) that will be passed to the group callback when all	1496	Set the result value(s) that will be passed to the group callback when all
930	subrequests have finished and set thre groups errno to the current value	1497	subrequests have finished and set the groups errno to the current value
931	of errno (just like calling C<errno> without an error number). By default,	1498	of errno (just like calling C<errno> without an error number). By default,
932	no argument will be passed and errno is zero.	1499	no argument will be passed and errno is zero.
933		1500
934	=item $grp->errno ([$errno])	1501	=item $grp->errno ([$errno])
935		1502
…		…
946	=item feed $grp $callback->($grp)	1513	=item feed $grp $callback->($grp)
947		1514
948	Sets a feeder/generator on this group: every group can have an attached	1515	Sets a feeder/generator on this group: every group can have an attached
949	generator that generates requests if idle. The idea behind this is that,	1516	generator that generates requests if idle. The idea behind this is that,
950	although you could just queue as many requests as you want in a group,	1517	although you could just queue as many requests as you want in a group,
951	this might starve other requests for a potentially long time. For	1518	this might starve other requests for a potentially long time. For example,
952	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1519	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
953	requests, delaying any later requests for a long time.	1520	requests, delaying any later requests for a long time.
954		1521
955	To avoid this, and allow incremental generation of requests, you can	1522	To avoid this, and allow incremental generation of requests, you can
956	instead a group and set a feeder on it that generates those requests. The	1523	instead a group and set a feeder on it that generates those requests. The
957	feed callback will be called whenever there are few enough (see C<limit>,	1524	feed callback will be called whenever there are few enough (see C<limit>,
…		…
962	not impose any limits).	1529	not impose any limits).
963		1530
964	If the feed does not queue more requests when called, it will be	1531	If the feed does not queue more requests when called, it will be
965	automatically removed from the group.	1532	automatically removed from the group.
966		1533
967	If the feed limit is C<0>, it will be set to C<2> automatically.	1534	If the feed limit is C<0> when this method is called, it will be set to
		1535	C<2> automatically.
968		1536
969	Example:	1537	Example:
970		1538
971	# stat all files in @files, but only ever use four aio requests concurrently:	1539	# stat all files in @files, but only ever use four aio requests concurrently:
972		1540
…		…
984	Sets the feeder limit for the group: The feeder will be called whenever	1552	Sets the feeder limit for the group: The feeder will be called whenever
985	the group contains less than this many requests.	1553	the group contains less than this many requests.
986		1554
987	Setting the limit to C<0> will pause the feeding process.	1555	Setting the limit to C<0> will pause the feeding process.
988		1556
		1557	The default value for the limit is C<0>, but note that setting a feeder
		1558	automatically bumps it up to C<2>.
		1559
989	=back	1560	=back
990		1561
991	=head2 SUPPORT FUNCTIONS	1562	=head2 SUPPORT FUNCTIONS
992		1563
993	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1564	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
…		…
995	=over 4	1566	=over 4
996		1567
997	=item $fileno = IO::AIO::poll_fileno	1568	=item $fileno = IO::AIO::poll_fileno
998		1569
999	Return the I<request result pipe file descriptor>. This filehandle must be	1570	Return the I<request result pipe file descriptor>. This filehandle must be
1000	polled for reading by some mechanism outside this module (e.g. Event or	1571	polled for reading by some mechanism outside this module (e.g. EV, Glib,
1001	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1572	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1002	to call C<poll_cb> to check the results.	1573	you have to call C<poll_cb> to check the results.
1003		1574
1004	See C<poll_cb> for an example.	1575	See C<poll_cb> for an example.
1005		1576
1006	=item IO::AIO::poll_cb	1577	=item IO::AIO::poll_cb
1007		1578
1008	Process some outstanding events on the result pipe. You have to call this	1579	Process some outstanding events on the result pipe. You have to call
1009	regularly. Returns the number of events processed. Returns immediately	1580	this regularly. Returns C<0> if all events could be processed (or there
1010	when no events are outstanding. The amount of events processed depends on	1581	were no events to process), or C<-1> if it returned earlier for whatever
1011	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.	1582	reason. Returns immediately when no events are outstanding. The amount of
		1583	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1584	C<IO::AIO::max_poll_time>.
1012		1585
1013	If not all requests were processed for whatever reason, the filehandle	1586	If not all requests were processed for whatever reason, the filehandle
1014	will still be ready when C<poll_cb> returns.	1587	will still be ready when C<poll_cb> returns, so normally you don't have to
		1588	do anything special to have it called later.
		1589
		1590	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1591	ready, it can be beneficial to call this function from loops which submit
		1592	a lot of requests, to make sure the results get processed when they become
		1593	available and not just when the loop is finished and the event loop takes
		1594	over again. This function returns very fast when there are no outstanding
		1595	requests.
1015		1596
1016	Example: Install an Event watcher that automatically calls	1597	Example: Install an Event watcher that automatically calls
1017	IO::AIO::poll_cb with high priority:	1598	IO::AIO::poll_cb with high priority (more examples can be found in the
		1599	SYNOPSIS section, at the top of this document):
1018		1600
1019	Event->io (fd => IO::AIO::poll_fileno,	1601	Event->io (fd => IO::AIO::poll_fileno,
1020	poll => 'r', async => 1,	1602	poll => 'r', async => 1,
1021	cb => \&IO::AIO::poll_cb);	1603	cb => \&IO::AIO::poll_cb);
		1604
		1605	=item IO::AIO::poll_wait
		1606
		1607	If there are any outstanding requests and none of them in the result
		1608	phase, wait till the result filehandle becomes ready for reading (simply
		1609	does a C<select> on the filehandle. This is useful if you want to
		1610	synchronously wait for some requests to finish).
		1611
		1612	See C<nreqs> for an example.
		1613
		1614	=item IO::AIO::poll
		1615
		1616	Waits until some requests have been handled.
		1617
		1618	Returns the number of requests processed, but is otherwise strictly
		1619	equivalent to:
		1620
		1621	IO::AIO::poll_wait, IO::AIO::poll_cb
		1622
		1623	=item IO::AIO::flush
		1624
		1625	Wait till all outstanding AIO requests have been handled.
		1626
		1627	Strictly equivalent to:
		1628
		1629	IO::AIO::poll_wait, IO::AIO::poll_cb
		1630	while IO::AIO::nreqs;
1022		1631
1023	=item IO::AIO::max_poll_reqs $nreqs	1632	=item IO::AIO::max_poll_reqs $nreqs
1024		1633
1025	=item IO::AIO::max_poll_time $seconds	1634	=item IO::AIO::max_poll_time $seconds
1026		1635
…		…
1051	# use a low priority so other tasks have priority	1660	# use a low priority so other tasks have priority
1052	Event->io (fd => IO::AIO::poll_fileno,	1661	Event->io (fd => IO::AIO::poll_fileno,
1053	poll => 'r', nice => 1,	1662	poll => 'r', nice => 1,
1054	cb => &IO::AIO::poll_cb);	1663	cb => &IO::AIO::poll_cb);
1055		1664
1056	=item IO::AIO::poll_wait
1057
1058	If there are any outstanding requests and none of them in the result
1059	phase, wait till the result filehandle becomes ready for reading (simply
1060	does a C<select> on the filehandle. This is useful if you want to
1061	synchronously wait for some requests to finish).
1062
1063	See C<nreqs> for an example.
1064
1065	=item IO::AIO::poll
1066
1067	Waits until some requests have been handled.
1068
1069	Returns the number of requests processed, but is otherwise strictly
1070	equivalent to:
1071
1072	IO::AIO::poll_wait, IO::AIO::poll_cb
1073
1074	=item IO::AIO::flush
1075
1076	Wait till all outstanding AIO requests have been handled.
1077
1078	Strictly equivalent to:
1079
1080	IO::AIO::poll_wait, IO::AIO::poll_cb
1081	while IO::AIO::nreqs;
1082
1083	=back	1665	=back
1084		1666
1085	=head3 CONTROLLING THE NUMBER OF THREADS	1667	=head3 CONTROLLING THE NUMBER OF THREADS
1086		1668
1087	=over	1669	=over
…		…
1120		1702
1121	Under normal circumstances you don't need to call this function.	1703	Under normal circumstances you don't need to call this function.
1122		1704
1123	=item IO::AIO::max_idle $nthreads	1705	=item IO::AIO::max_idle $nthreads
1124		1706
1125	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1707	Limit the number of threads (default: 4) that are allowed to idle
1126	threads that did not get a request to process within 10 seconds). That	1708	(i.e., threads that did not get a request to process within the idle
1127	means if a thread becomes idle while C<$nthreads> other threads are also	1709	timeout (default: 10 seconds). That means if a thread becomes idle while
1128	idle, it will free its resources and exit.	1710	C<$nthreads> other threads are also idle, it will free its resources and
		1711	exit.
1129		1712
1130	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1713	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1131	to allow for extremely high load situations, but want to free resources	1714	to allow for extremely high load situations, but want to free resources
1132	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1715	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1133		1716
1134	The default is probably ok in most situations, especially if thread	1717	The default is probably ok in most situations, especially if thread
1135	creation is fast. If thread creation is very slow on your system you might	1718	creation is fast. If thread creation is very slow on your system you might
1136	want to use larger values.	1719	want to use larger values.
1137		1720
		1721	=item IO::AIO::idle_timeout $seconds
		1722
		1723	Sets the minimum idle timeout (default 10) after which worker threads are
		1724	allowed to exit. SEe C<IO::AIO::max_idle>.
		1725
1138	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1726	=item IO::AIO::max_outstanding $maxreqs
		1727
		1728	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1729	you do queue up more than this number of requests, the next call to
		1730	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1731	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1732	longer exceeded.
		1733
		1734	In other words, this setting does not enforce a queue limit, but can be
		1735	used to make poll functions block if the limit is exceeded.
1139		1736
1140	This is a very bad function to use in interactive programs because it	1737	This is a very bad function to use in interactive programs because it
1141	blocks, and a bad way to reduce concurrency because it is inexact: Better	1738	blocks, and a bad way to reduce concurrency because it is inexact: Better
1142	use an C<aio_group> together with a feed callback.	1739	use an C<aio_group> together with a feed callback.
1143		1740
1144	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1741	It's main use is in scripts without an event loop - when you want to stat
1145	to queue up more than this number of requests, the next call to the	1742	a lot of files, you can write somehting like this:
1146	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1147	function will block until the limit is no longer exceeded.
1148		1743
1149	The default value is very large, so there is no practical limit on the	1744	IO::AIO::max_outstanding 32;
1150	number of outstanding requests.
1151		1745
1152	You can still queue as many requests as you want. Therefore,	1746	for my $path (...) {
1153	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	1747	aio_stat $path , ...;
1154	as a stop gap to shield against fatal memory overflow (with large values).	1748	IO::AIO::poll_cb;
		1749	}
		1750
		1751	IO::AIO::flush;
		1752
		1753	The call to C<poll_cb> inside the loop will normally return instantly, but
		1754	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1755	some requests have been handled. This keeps the loop from pushing a large
		1756	number of C<aio_stat> requests onto the queue.
		1757
		1758	The default value for C<max_outstanding> is very large, so there is no
		1759	practical limit on the number of outstanding requests.
1155		1760
1156	=back	1761	=back
1157		1762
1158	=head3 STATISTICAL INFORMATION	1763	=head3 STATISTICAL INFORMATION
1159		1764
…		…
1179	Returns the number of requests currently in the pending state (executed,	1784	Returns the number of requests currently in the pending state (executed,
1180	but not yet processed by poll_cb).	1785	but not yet processed by poll_cb).
1181		1786
1182	=back	1787	=back
1183		1788
		1789	=head3 MISCELLANEOUS FUNCTIONS
		1790
		1791	IO::AIO implements some functions that might be useful, but are not
		1792	asynchronous.
		1793
		1794	=over 4
		1795
		1796	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1797
		1798	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1799	but is blocking (this makes most sense if you know the input data is
		1800	likely cached already and the output filehandle is set to non-blocking
		1801	operations).
		1802
		1803	Returns the number of bytes copied, or C<-1> on error.
		1804
		1805	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1806
		1807	Simply calls the C<posix_fadvise> function (see its
		1808	manpage for details). The following advice constants are
		1809	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1810	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1811	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1812
		1813	On systems that do not implement C<posix_fadvise>, this function returns
		1814	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1815
		1816	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1817
		1818	Simply calls the C<posix_madvise> function (see its
		1819	manpage for details). The following advice constants are
		1820	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1821	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1822
		1823	On systems that do not implement C<posix_madvise>, this function returns
		1824	ENOSYS, otherwise the return value of C<posix_madvise>.
		1825
		1826	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1827
		1828	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1829	$scalar (see its manpage for details). The following protect
		1830	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1831	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1832
		1833	On systems that do not implement C<mprotect>, this function returns
		1834	ENOSYS, otherwise the return value of C<mprotect>.
		1835
		1836	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1837
		1838	Memory-maps a file (or anonymous memory range) and attaches it to the
		1839	given C<$scalar>, which will act like a string scalar.
		1840
		1841	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1842	change the string length, and most read-only operations such as copying it
		1843	or searching it with regexes and so on.
		1844
		1845	Anything else is unsafe and will, at best, result in memory leaks.
		1846
		1847	The memory map associated with the C<$scalar> is automatically removed
		1848	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1849	C<IO::AIO::munmap> functions are called.
		1850
		1851	This calls the C<mmap>(2) function internally. See your system's manual
		1852	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1853
		1854	The C<$length> must be larger than zero and smaller than the actual
		1855	filesize.
		1856
		1857	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1858	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1859
		1860	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1861	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1862	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1863	(which is set to C<MAP_ANON> if your system only provides this
		1864	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1865	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1866	C<IO::AIO::MAP_NONBLOCK>
		1867
		1868	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1869
		1870	C<$offset> is the offset from the start of the file - it generally must be
		1871	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1872
		1873	Example:
		1874
		1875	use Digest::MD5;
		1876	use IO::AIO;
		1877
		1878	open my $fh, "<verybigfile"
		1879	or die "$!";
		1880
		1881	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1882	or die "verybigfile: $!";
		1883
		1884	my $fast_md5 = md5 $data;
		1885
		1886	=item IO::AIO::munmap $scalar
		1887
		1888	Removes a previous mmap and undefines the C<$scalar>.
		1889
		1890	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1891
		1892	Calls the C<munlock> function, undoing the effects of a previous
		1893	C<aio_mlock> call (see its description for details).
		1894
		1895	=item IO::AIO::munlockall
		1896
		1897	Calls the C<munlockall> function.
		1898
		1899	On systems that do not implement C<munlockall>, this function returns
		1900	ENOSYS, otherwise the return value of C<munlockall>.
		1901
		1902	=back
		1903
1184	=cut	1904	=cut
1185		1905
1186	# support function to convert a fd into a perl filehandle
1187	sub _fd2fh {
1188	return undef if $_[0] < 0;
1189
1190	# try to generate nice filehandles
1191	my $sym = "IO::AIO::fd#$_[0]";
1192	local *$sym;
1193
1194	open *$sym, "+<&=$_[0]" # usually works under any unix
1195	or open *$sym, "<&=$_[0]" # cygwin needs this
1196	or open *$sym, ">&=$_[0]" # or this
1197	or return undef;
1198
1199	*$sym
1200	}
1201
1202	min_parallel 8;	1906	min_parallel 8;
1203		1907
1204	END { flush }	1908	END { flush }
1205		1909
1206	1;	1910	1;
1207		1911
		1912	=head1 EVENT LOOP INTEGRATION
		1913
		1914	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1915	automatically into many event loops:
		1916
		1917	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1918	use AnyEvent::AIO;
		1919
		1920	You can also integrate IO::AIO manually into many event loops, here are
		1921	some examples of how to do this:
		1922
		1923	# EV integration
		1924	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1925
		1926	# Event integration
		1927	Event->io (fd => IO::AIO::poll_fileno,
		1928	poll => 'r',
		1929	cb => \&IO::AIO::poll_cb);
		1930
		1931	# Glib/Gtk2 integration
		1932	add_watch Glib::IO IO::AIO::poll_fileno,
		1933	in => sub { IO::AIO::poll_cb; 1 };
		1934
		1935	# Tk integration
		1936	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1937	readable => \&IO::AIO::poll_cb);
		1938
		1939	# Danga::Socket integration
		1940	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1941	\&IO::AIO::poll_cb);
		1942
1208	=head2 FORK BEHAVIOUR	1943	=head2 FORK BEHAVIOUR
1209		1944
1210	This module should do "the right thing" when the process using it forks:	1945	Usage of pthreads in a program changes the semantics of fork
		1946	considerably. Specifically, only async-safe functions can be called after
		1947	fork. Perl doesn't know about this, so in general, you cannot call fork
		1948	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		1949	pthreads, so this applies, but many other extensions and (for inexplicable
		1950	reasons) perl itself often is linked against pthreads, so this limitation
		1951	applies to quite a lot of perls.
1211		1952
1212	Before the fork, IO::AIO enters a quiescent state where no requests	1953	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1213	can be added in other threads and no results will be processed. After	1954	only works in the process that loaded it. Forking is fully supported, but
1214	the fork the parent simply leaves the quiescent state and continues	1955	using IO::AIO in the child is not.
1215	request/result processing, while the child frees the request/result queue
1216	(so that the requests started before the fork will only be handled in the
1217	parent). Threads will be started on demand until the limit set in the
1218	parent process has been reached again.
1219		1956
1220	In short: the parent will, after a short pause, continue as if fork had	1957	You might get around by not I<using> IO::AIO before (or after)
1221	not been called, while the child will act as if IO::AIO has not been used	1958	forking. You could also try to call the L<IO::AIO::reinit> function in the
1222	yet.	1959	child:
		1960
		1961	=over 4
		1962
		1963	=item IO::AIO::reinit
		1964
		1965	Abandons all current requests and I/O threads and simply reinitialises all
		1966	data structures. This is not an operation supported by any standards, but
		1967	happens to work on GNU/Linux and some newer BSD systems.
		1968
		1969	The only reasonable use for this function is to call it after forking, if
		1970	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		1971	the process will result in undefined behaviour. Calling it at any time
		1972	will also result in any undefined (by POSIX) behaviour.
		1973
		1974	=back
1223		1975
1224	=head2 MEMORY USAGE	1976	=head2 MEMORY USAGE
1225		1977
1226	Per-request usage:	1978	Per-request usage:
1227		1979
…		…
1229	bytes of memory. In addition, stat requests need a stat buffer (possibly	1981	bytes of memory. In addition, stat requests need a stat buffer (possibly
1230	a few hundred bytes), readdir requires a result buffer and so on. Perl	1982	a few hundred bytes), readdir requires a result buffer and so on. Perl
1231	scalars and other data passed into aio requests will also be locked and	1983	scalars and other data passed into aio requests will also be locked and
1232	will consume memory till the request has entered the done state.	1984	will consume memory till the request has entered the done state.
1233		1985
1234	This is now awfully much, so queuing lots of requests is not usually a	1986	This is not awfully much, so queuing lots of requests is not usually a
1235	problem.	1987	problem.
1236		1988
1237	Per-thread usage:	1989	Per-thread usage:
1238		1990
1239	In the execution phase, some aio requests require more memory for	1991	In the execution phase, some aio requests require more memory for
…		…
1244		1996
1245	Known bugs will be fixed in the next release.	1997	Known bugs will be fixed in the next release.
1246		1998
1247	=head1 SEE ALSO	1999	=head1 SEE ALSO
1248		2000
1249	L<Coro::AIO>.	2001	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		2002	more natural syntax.
1250		2003
1251	=head1 AUTHOR	2004	=head1 AUTHOR
1252		2005
1253	Marc Lehmann <schmorp@schmorp.de>	2006	Marc Lehmann <schmorp@schmorp.de>
1254	http://home.schmorp.de/	2007	http://home.schmorp.de/

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