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Revision 1.105 by root, Sun Mar 25 00:20:27 2007 UTC vs.
Revision 1.203 by root, Thu Jul 7 22:36:18 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 = '3.93';
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 aio_fsync
		178	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
201	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));	186	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
202	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	187	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
203	min_parallel max_parallel max_idle	188	min_parallel max_parallel max_idle idle_timeout
204	nreqs nready npending nthreads	189	nreqs nready npending nthreads
205	max_poll_time max_poll_reqs);	190	max_poll_time max_poll_reqs
		191	sendfile fadvise madvise
		192	mmap munmap munlock munlockall);
		193
		194	push @AIO_REQ, qw(aio_busy); # not exported
206		195
207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	196	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
208		197
209	require XSLoader;	198	require XSLoader;
210	XSLoader::load ("IO::AIO", $VERSION);	199	XSLoader::load ("IO::AIO", $VERSION);
211	}	200	}
212		201
213	=head1 FUNCTIONS	202	=head1 FUNCTIONS
		203
		204	=head2 QUICK OVERVIEW
		205
		206	This section simply lists the prototypes of the most important functions
		207	for quick reference. See the following sections for function-by-function
		208	documentation.
		209
		210	aio_open $pathname, $flags, $mode, $callback->($fh)
		211	aio_close $fh, $callback->($status)
		212	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		213	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		214	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		215	aio_readahead $fh,$offset,$length, $callback->($retval)
		216	aio_stat $fh_or_path, $callback->($status)
		217	aio_lstat $fh, $callback->($status)
		218	aio_statvfs $fh_or_path, $callback->($statvfs)
		219	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		220	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		221	aio_truncate $fh_or_path, $offset, $callback->($status)
		222	aio_chmod $fh_or_path, $mode, $callback->($status)
		223	aio_unlink $pathname, $callback->($status)
		224	aio_mknod $path, $mode, $dev, $callback->($status)
		225	aio_link $srcpath, $dstpath, $callback->($status)
		226	aio_symlink $srcpath, $dstpath, $callback->($status)
		227	aio_readlink $path, $callback->($link)
		228	aio_realpath $path, $callback->($link)
		229	aio_rename $srcpath, $dstpath, $callback->($status)
		230	aio_mkdir $pathname, $mode, $callback->($status)
		231	aio_rmdir $pathname, $callback->($status)
		232	aio_readdir $pathname, $callback->($entries)
		233	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		234	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		235	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		236	aio_load $path, $data, $callback->($status)
		237	aio_copy $srcpath, $dstpath, $callback->($status)
		238	aio_move $srcpath, $dstpath, $callback->($status)
		239	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		240	aio_rmtree $path, $callback->($status)
		241	aio_sync $callback->($status)
		242	aio_fsync $fh, $callback->($status)
		243	aio_fdatasync $fh, $callback->($status)
		244	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		245	aio_pathsync $path, $callback->($status)
		246	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		247	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		248	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		249	aio_mlockall $flags, $callback->($status)
		250	aio_group $callback->(...)
		251	aio_nop $callback->()
		252
		253	$prev_pri = aioreq_pri [$pri]
		254	aioreq_nice $pri_adjust
		255
		256	IO::AIO::poll_wait
		257	IO::AIO::poll_cb
		258	IO::AIO::poll
		259	IO::AIO::flush
		260	IO::AIO::max_poll_reqs $nreqs
		261	IO::AIO::max_poll_time $seconds
		262	IO::AIO::min_parallel $nthreads
		263	IO::AIO::max_parallel $nthreads
		264	IO::AIO::max_idle $nthreads
		265	IO::AIO::idle_timeout $seconds
		266	IO::AIO::max_outstanding $maxreqs
		267	IO::AIO::nreqs
		268	IO::AIO::nready
		269	IO::AIO::npending
		270
		271	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		272	IO::AIO::fadvise $fh, $offset, $len, $advice
		273	IO::AIO::madvise $scalar, $offset, $length, $advice
		274	IO::AIO::mprotect $scalar, $offset, $length, $protect
		275	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		276	IO::AIO::munlockall
214		277
215	=head2 AIO REQUEST FUNCTIONS	278	=head2 AIO REQUEST FUNCTIONS
216		279
217	All the C<aio_*> calls are more or less thin wrappers around the syscall	280	All the C<aio_*> calls are more or less thin wrappers around the syscall
218	with the same name (sans C<aio_>). The arguments are similar or identical,	281	with the same name (sans C<aio_>). The arguments are similar or identical,
219	and they all accept an additional (and optional) C<$callback> argument	282	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	283	which must be a code reference. This code reference will get called with
221	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	284	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
222	perl, which usually delivers "false") as it's sole argument when the given	285	perl, which usually delivers "false") as its sole argument after the given
223	syscall has been executed asynchronously.	286	syscall has been executed asynchronously.
224		287
225	All functions expecting a filehandle keep a copy of the filehandle	288	All functions expecting a filehandle keep a copy of the filehandle
226	internally until the request has finished.	289	internally until the request has finished.
227		290
…		…
241	your pathnames to the locale (or other) encoding in effect in the user	304	your pathnames to the locale (or other) encoding in effect in the user
242	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	305	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
243	use something else to ensure your scalar has the correct contents.	306	use something else to ensure your scalar has the correct contents.
244		307
245	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	308	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
246	handles correctly wether it is set or not.	309	handles correctly whether it is set or not.
247		310
248	=over 4	311	=over 4
249		312
250	=item $prev_pri = aioreq_pri [$pri]	313	=item $prev_pri = aioreq_pri [$pri]
251		314
…		…
271	aio_read $_[0], ..., sub {	334	aio_read $_[0], ..., sub {
272	...	335	...
273	};	336	};
274	};	337	};
275		338
		339
276	=item aioreq_nice $pri_adjust	340	=item aioreq_nice $pri_adjust
277		341
278	Similar to C<aioreq_pri>, but subtracts the given value from the current	342	Similar to C<aioreq_pri>, but subtracts the given value from the current
279	priority, so the effect is cumulative.	343	priority, so the effect is cumulative.
		344
280		345
281	=item aio_open $pathname, $flags, $mode, $callback->($fh)	346	=item aio_open $pathname, $flags, $mode, $callback->($fh)
282		347
283	Asynchronously open or create a file and call the callback with a newly	348	Asynchronously open or create a file and call the callback with a newly
284	created filehandle for the file.	349	created filehandle for the file.
…		…
296	by the umask in effect then the request is being executed, so better never	361	by the umask in effect then the request is being executed, so better never
297	change the umask.	362	change the umask.
298		363
299	Example:	364	Example:
300		365
301	aio_open "/etc/passwd", O_RDONLY, 0, sub {	366	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
302	if ($_[0]) {	367	if ($_[0]) {
303	print "open successful, fh is $_[0]\n";	368	print "open successful, fh is $_[0]\n";
304	...	369	...
305	} else {	370	} else {
306	die "open failed: $!\n";	371	die "open failed: $!\n";
307	}	372	}
308	};	373	};
309		374
		375	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		376	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		377	following POSIX and non-POSIX constants are available (missing ones on
		378	your system are, as usual, C<0>):
		379
		380	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		381	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		382	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		383
		384
310	=item aio_close $fh, $callback->($status)	385	=item aio_close $fh, $callback->($status)
311		386
312	Asynchronously close a file and call the callback with the result	387	Asynchronously close a file and call the callback with the result
313	code. I<WARNING:> although accepted, you should not pass in a perl	388	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		389
318	This is supposed to be a bug in the API, so that might change. It's	390	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
319	therefore best to avoid this function.	391	closing the file descriptor associated with the filehandle itself.
		392
		393	Therefore, C<aio_close> will not close the filehandle - instead it will
		394	use dup2 to overwrite the file descriptor with the write-end of a pipe
		395	(the pipe fd will be created on demand and will be cached).
		396
		397	Or in other words: the file descriptor will be closed, but it will not be
		398	free for reuse until the perl filehandle is closed.
		399
		400	=cut
320		401
321	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	402	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
322		403
323	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	404	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
324		405
325	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	406	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	407	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
327	callback without the actual number of bytes read (or -1 on error, just	408	and calls the callback without the actual number of bytes read (or -1 on
328	like the syscall).	409	error, just like the syscall).
		410
		411	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		412	offset plus the actual number of bytes read.
		413
		414	If C<$offset> is undefined, then the current file descriptor offset will
		415	be used (and updated), otherwise the file descriptor offset will not be
		416	changed by these calls.
		417
		418	If C<$length> is undefined in C<aio_write>, use the remaining length of
		419	C<$data>.
		420
		421	If C<$dataoffset> is less than zero, it will be counted from the end of
		422	C<$data>.
329		423
330	The C<$data> scalar I<MUST NOT> be modified in any way while the request	424	The C<$data> scalar I<MUST NOT> be modified in any way while the request
331	is outstanding. Modifying it can result in segfaults or WW3 (if the	425	is outstanding. Modifying it can result in segfaults or World War III (if
332	necessary/optional hardware is installed).	426	the necessary/optional hardware is installed).
333		427
334	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	428	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
335	offset C<0> within the scalar:	429	offset C<0> within the scalar:
336		430
337	aio_read $fh, 7, 15, $buffer, 0, sub {	431	aio_read $fh, 7, 15, $buffer, 0, sub {
338	$_[0] > 0 or die "read error: $!";	432	$_[0] > 0 or die "read error: $!";
339	print "read $_[0] bytes: <$buffer>\n";	433	print "read $_[0] bytes: <$buffer>\n";
340	};	434	};
341		435
		436
342	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	437	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
343		438
344	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	439	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
345	reading at byte offset C<$in_offset>, and starts writing at the current	440	reading at byte offset C<$in_offset>, and starts writing at the current
346	file offset of C<$out_fh>. Because of that, it is not safe to issue more	441	file offset of C<$out_fh>. Because of that, it is not safe to issue more
347	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	442	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
348	other.	443	other. The same C<$in_fh> works fine though, as this function does not
		444	move or use the file offset of C<$in_fh>.
349		445
		446	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		447	are written, and there is no way to find out how many more bytes have been
		448	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		449	number of bytes written to C<$out_fh>. Only if the result value equals
		450	C<$length> one can assume that C<$length> bytes have been read.
		451
		452	Unlike with other C<aio_> functions, it makes a lot of sense to use
		453	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		454	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		455	the socket I/O will be non-blocking. Note, however, that you can run
		456	into a trap where C<aio_sendfile> reads some data with readahead, then
		457	fails to write all data, and when the socket is ready the next time, the
		458	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		459	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		460	resource usage.
		461
350	This call tries to make use of a native C<sendfile> syscall to provide	462	This call tries to make use of a native C<sendfile>-like syscall to
351	zero-copy operation. For this to work, C<$out_fh> should refer to a	463	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.	464	a socket, and C<$in_fh> should refer to an mmap'able file.
353		465
354	If the native sendfile call fails or is not implemented, it will be	466	If a native sendfile cannot be found or it fails with C<ENOSYS>,
355	emulated, so you can call C<aio_sendfile> on any type of filehandle	467	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		468	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
356	regardless of the limitations of the operating system.	469	type of filehandle regardless of the limitations of the operating system.
357		470
358	Please note, however, that C<aio_sendfile> can read more bytes from	471	As native sendfile syscalls (as practically any non-POSIX interface hacked
359	C<$in_fh> than are written, and there is no way to find out how many	472	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	473	on many systems, this implementation tries to work around some known bugs
361	provides the number of bytes written to C<$out_fh>. Only if the result	474	in Linux and FreeBSD kernels (probably others, too), but that might fail,
362	value equals C<$length> one can assume that C<$length> bytes have been	475	so you really really should check the return value of C<aio_sendfile> -
363	read.	476	fewre bytes than expected might have been transferred.
		477
364		478
365	=item aio_readahead $fh,$offset,$length, $callback->($retval)	479	=item aio_readahead $fh,$offset,$length, $callback->($retval)
366		480
367	C<aio_readahead> populates the page cache with data from a file so that	481	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<$offset>	482	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
374	file. The current file offset of the file is left unchanged.	488	file. The current file offset of the file is left unchanged.
375		489
376	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	490	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.	491	emulated by simply reading the data, which would have a similar effect.
378		492
		493
379	=item aio_stat $fh_or_path, $callback->($status)	494	=item aio_stat $fh_or_path, $callback->($status)
380		495
381	=item aio_lstat $fh, $callback->($status)	496	=item aio_lstat $fh, $callback->($status)
382		497
383	Works like perl's C<stat> or C<lstat> in void context. The callback will	498	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
388	for an explanation.	503	for an explanation.
389		504
390	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	505	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	506	error when stat'ing a large file, the results will be silently truncated
392	unless perl itself is compiled with large file support.	507	unless perl itself is compiled with large file support.
		508
		509	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		510	following constants and functions (if not implemented, the constants will
		511	be C<0> and the functions will either C<croak> or fall back on traditional
		512	behaviour).
		513
		514	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		515	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		516	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
393		517
394	Example: Print the length of F</etc/passwd>:	518	Example: Print the length of F</etc/passwd>:
395		519
396	aio_stat "/etc/passwd", sub {	520	aio_stat "/etc/passwd", sub {
397	$_[0] and die "stat failed: $!";	521	$_[0] and die "stat failed: $!";
398	print "size is ", -s _, "\n";	522	print "size is ", -s _, "\n";
399	};	523	};
400		524
		525
		526	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		527
		528	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		529	whether a file handle or path was passed.
		530
		531	On success, the callback is passed a hash reference with the following
		532	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		533	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		534	is passed.
		535
		536	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		537	C<ST_NOSUID>.
		538
		539	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		540	their correct value when available, or to C<0> on systems that do
		541	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		542	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		543	C<ST_NODIRATIME> and C<ST_RELATIME>.
		544
		545	Example: stat C</wd> and dump out the data if successful.
		546
		547	aio_statvfs "/wd", sub {
		548	my $f = $_[0]
		549	or die "statvfs: $!";
		550
		551	use Data::Dumper;
		552	say Dumper $f;
		553	};
		554
		555	# result:
		556	{
		557	bsize => 1024,
		558	bfree => 4333064312,
		559	blocks => 10253828096,
		560	files => 2050765568,
		561	flag => 4096,
		562	favail => 2042092649,
		563	bavail => 4333064312,
		564	ffree => 2042092649,
		565	namemax => 255,
		566	frsize => 1024,
		567	fsid => 1810
		568	}
		569
		570
		571	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		572
		573	Works like perl's C<utime> function (including the special case of $atime
		574	and $mtime being undef). Fractional times are supported if the underlying
		575	syscalls support them.
		576
		577	When called with a pathname, uses utimes(2) if available, otherwise
		578	utime(2). If called on a file descriptor, uses futimes(2) if available,
		579	otherwise returns ENOSYS, so this is not portable.
		580
		581	Examples:
		582
		583	# set atime and mtime to current time (basically touch(1)):
		584	aio_utime "path", undef, undef;
		585	# set atime to current time and mtime to beginning of the epoch:
		586	aio_utime "path", time, undef; # undef==0
		587
		588
		589	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		590
		591	Works like perl's C<chown> function, except that C<undef> for either $uid
		592	or $gid is being interpreted as "do not change" (but -1 can also be used).
		593
		594	Examples:
		595
		596	# same as "chown root path" in the shell:
		597	aio_chown "path", 0, -1;
		598	# same as above:
		599	aio_chown "path", 0, undef;
		600
		601
		602	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		603
		604	Works like truncate(2) or ftruncate(2).
		605
		606
		607	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		608
		609	Works like perl's C<chmod> function.
		610
		611
401	=item aio_unlink $pathname, $callback->($status)	612	=item aio_unlink $pathname, $callback->($status)
402		613
403	Asynchronously unlink (delete) a file and call the callback with the	614	Asynchronously unlink (delete) a file and call the callback with the
404	result code.	615	result code.
405		616
		617
406	=item aio_mknod $path, $mode, $dev, $callback->($status)	618	=item aio_mknod $path, $mode, $dev, $callback->($status)
407		619
408	[EXPERIMENTAL]	620	[EXPERIMENTAL]
409		621
410	Asynchronously create a device node (or fifo). See mknod(2).	622	Asynchronously create a device node (or fifo). See mknod(2).
411		623
412	The only (POSIX-) portable way of calling this function is:	624	The only (POSIX-) portable way of calling this function is:
413		625
414	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	626	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		627
		628	See C<aio_stat> for info about some potentially helpful extra constants
		629	and functions.
415		630
416	=item aio_link $srcpath, $dstpath, $callback->($status)	631	=item aio_link $srcpath, $dstpath, $callback->($status)
417		632
418	Asynchronously create a new link to the existing object at C<$srcpath> at	633	Asynchronously create a new link to the existing object at C<$srcpath> at
419	the path C<$dstpath> and call the callback with the result code.	634	the path C<$dstpath> and call the callback with the result code.
420		635
		636
421	=item aio_symlink $srcpath, $dstpath, $callback->($status)	637	=item aio_symlink $srcpath, $dstpath, $callback->($status)
422		638
423	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	639	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
424	the path C<$dstpath> and call the callback with the result code.	640	the path C<$dstpath> and call the callback with the result code.
		641
425		642
426	=item aio_readlink $path, $callback->($link)	643	=item aio_readlink $path, $callback->($link)
427		644
428	Asynchronously read the symlink specified by C<$path> and pass it to	645	Asynchronously read the symlink specified by C<$path> and pass it to
429	the callback. If an error occurs, nothing or undef gets passed to the	646	the callback. If an error occurs, nothing or undef gets passed to the
430	callback.	647	callback.
431		648
		649
		650	=item aio_realpath $path, $callback->($path)
		651
		652	Asynchronously make the path absolute and resolve any symlinks in
		653	C<$path>. The resulting path only consists of directories (Same as
		654	L<Cwd::realpath>).
		655
		656	This request can be used to get the absolute path of the current working
		657	directory by passing it a path of F<.> (a single dot).
		658
		659
432	=item aio_rename $srcpath, $dstpath, $callback->($status)	660	=item aio_rename $srcpath, $dstpath, $callback->($status)
433		661
434	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	662	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
435	rename(2) and call the callback with the result code.	663	rename(2) and call the callback with the result code.
		664
436		665
437	=item aio_mkdir $pathname, $mode, $callback->($status)	666	=item aio_mkdir $pathname, $mode, $callback->($status)
438		667
439	Asynchronously mkdir (create) a directory and call the callback with	668	Asynchronously mkdir (create) a directory and call the callback with
440	the result code. C<$mode> will be modified by the umask at the time the	669	the result code. C<$mode> will be modified by the umask at the time the
441	request is executed, so do not change your umask.	670	request is executed, so do not change your umask.
442		671
		672
443	=item aio_rmdir $pathname, $callback->($status)	673	=item aio_rmdir $pathname, $callback->($status)
444		674
445	Asynchronously rmdir (delete) a directory and call the callback with the	675	Asynchronously rmdir (delete) a directory and call the callback with the
446	result code.	676	result code.
		677
447		678
448	=item aio_readdir $pathname, $callback->($entries)	679	=item aio_readdir $pathname, $callback->($entries)
449		680
450	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	681	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	682	directory (i.e. opendir + readdir + closedir). The entries will not be
452	sorted, and will B<NOT> include the C<.> and C<..> entries.	683	sorted, and will B<NOT> include the C<.> and C<..> entries.
453		684
454	The callback a single argument which is either C<undef> or an array-ref	685	The callback is passed a single argument which is either C<undef> or an
455	with the filenames.	686	array-ref with the filenames.
		687
		688
		689	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		690
		691	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		692	behaviour and output format. In case of an error, C<$entries> will be
		693	C<undef>.
		694
		695	The flags are a combination of the following constants, ORed together (the
		696	flags will also be passed to the callback, possibly modified):
		697
		698	=over 4
		699
		700	=item IO::AIO::READDIR_DENTS
		701
		702	When this flag is off, then the callback gets an arrayref consisting of
		703	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		704	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		705	entry in more detail.
		706
		707	C<$name> is the name of the entry.
		708
		709	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		710
		711	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		712	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		713	C<IO::AIO::DT_WHT>.
		714
		715	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		716	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		717	scalars are read-only: you can not modify them.
		718
		719	C<$inode> is the inode number (which might not be exact on systems with 64
		720	bit inode numbers and 32 bit perls). This field has unspecified content on
		721	systems that do not deliver the inode information.
		722
		723	=item IO::AIO::READDIR_DIRS_FIRST
		724
		725	When this flag is set, then the names will be returned in an order where
		726	likely directories come first, in optimal stat order. This is useful when
		727	you need to quickly find directories, or you want to find all directories
		728	while avoiding to stat() each entry.
		729
		730	If the system returns type information in readdir, then this is used
		731	to find directories directly. Otherwise, likely directories are names
		732	beginning with ".", or otherwise names with no dots, of which names with
		733	short names are tried first.
		734
		735	=item IO::AIO::READDIR_STAT_ORDER
		736
		737	When this flag is set, then the names will be returned in an order
		738	suitable for stat()'ing each one. That is, when you plan to stat()
		739	all files in the given directory, then the returned order will likely
		740	be fastest.
		741
		742	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		743	the likely dirs come first, resulting in a less optimal stat order.
		744
		745	=item IO::AIO::READDIR_FOUND_UNKNOWN
		746
		747	This flag should not be set when calling C<aio_readdirx>. Instead, it
		748	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		749	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		750	C<$type>'s are known, which can be used to speed up some algorithms.
		751
		752	=back
		753
456		754
457	=item aio_load $path, $data, $callback->($status)	755	=item aio_load $path, $data, $callback->($status)
458		756
459	This is a composite request that tries to fully load the given file into	757	This is a composite request that tries to fully load the given file into
460	memory. Status is the same as with aio_read.	758	memory. Status is the same as with aio_read.
461		759
462	=cut	760	=cut
463		761
464	sub aio_load($$;$) {	762	sub aio_load($$;$) {
465	aio_block {
466	my ($path, undef, $cb) = @_;	763	my ($path, undef, $cb) = @_;
467	my $data = \$_[1];	764	my $data = \$_[1];
468		765
469	my $pri = aioreq_pri;	766	my $pri = aioreq_pri;
470	my $grp = aio_group $cb;	767	my $grp = aio_group $cb;
		768
		769	aioreq_pri $pri;
		770	add $grp aio_open $path, O_RDONLY, 0, sub {
		771	my $fh = shift
		772	or return $grp->result (-1);
471		773
472	aioreq_pri $pri;	774	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), $$data, 0, sub {	775	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
479	$grp->result ($_[0]);	776	$grp->result ($_[0]);
480	};
481	};	777	};
482
483	$grp
484	}	778	};
		779
		780	$grp
485	}	781	}
486		782
487	=item aio_copy $srcpath, $dstpath, $callback->($status)	783	=item aio_copy $srcpath, $dstpath, $callback->($status)
488		784
489	Try to copy the I<file> (directories not supported as either source or	785	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	786	destination) from C<$srcpath> to C<$dstpath> and call the callback with
491	the C<0> (error) or C<-1> ok.	787	a status of C<0> (ok) or C<-1> (error, see C<$!>).
492		788
493	This is a composite request that it creates the destination file with	789	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	790	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	791	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
496	uid/gid, in that order.	792	uid/gid, in that order.
497		793
498	If an error occurs, the partial destination file will be unlinked, if	794	If an error occurs, the partial destination file will be unlinked, if
…		…
500	errors are being ignored.	796	errors are being ignored.
501		797
502	=cut	798	=cut
503		799
504	sub aio_copy($$;$) {	800	sub aio_copy($$;$) {
505	aio_block {
506	my ($src, $dst, $cb) = @_;	801	my ($src, $dst, $cb) = @_;
507		802
508	my $pri = aioreq_pri;	803	my $pri = aioreq_pri;
509	my $grp = aio_group $cb;	804	my $grp = aio_group $cb;
510		805
511	aioreq_pri $pri;	806	aioreq_pri $pri;
512	add $grp aio_open $src, O_RDONLY, 0, sub {	807	add $grp aio_open $src, O_RDONLY, 0, sub {
513	if (my $src_fh = $_[0]) {	808	if (my $src_fh = $_[0]) {
514	my @stat = stat $src_fh;	809	my @stat = stat $src_fh; # hmm, might block over nfs?
515		810
516	aioreq_pri $pri;	811	aioreq_pri $pri;
517	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	812	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
518	if (my $dst_fh = $_[0]) {	813	if (my $dst_fh = $_[0]) {
519	aioreq_pri $pri;	814	aioreq_pri $pri;
520	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	815	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
521	if ($_[0] == $stat[7]) {	816	if ($_[0] == $stat[7]) {
522	$grp->result (0);	817	$grp->result (0);
523	close $src_fh;	818	close $src_fh;
524		819
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 {	820	my $ch = sub {
531	$grp->result (-1);
532	close $src_fh;
533	close $dst_fh;
534
535	aioreq $pri;	821	aioreq_pri $pri;
		822	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		823	aioreq_pri $pri;
		824	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		825	aioreq_pri $pri;
536	add $grp aio_unlink $dst;	826	add $grp aio_close $dst_fh;
		827	}
		828	};
537	}	829	};
		830
		831	aioreq_pri $pri;
		832	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		833	if ($_[0] < 0 && $! == ENOSYS) {
		834	aioreq_pri $pri;
		835	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		836	} else {
		837	$ch->();
		838	}
		839	};
		840	} else {
		841	$grp->result (-1);
		842	close $src_fh;
		843	close $dst_fh;
		844
		845	aioreq $pri;
		846	add $grp aio_unlink $dst;
538	};	847	}
539	} else {
540	$grp->result (-1);
541	}	848	};
		849	} else {
		850	$grp->result (-1);
542	},	851	}
543
544	} else {
545	$grp->result (-1);
546	}	852	},
		853
		854	} else {
		855	$grp->result (-1);
547	};	856	}
548
549	$grp
550	}	857	};
		858
		859	$grp
551	}	860	}
552		861
553	=item aio_move $srcpath, $dstpath, $callback->($status)	862	=item aio_move $srcpath, $dstpath, $callback->($status)
554		863
555	Try to move the I<file> (directories not supported as either source or	864	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	865	destination) from C<$srcpath> to C<$dstpath> and call the callback with
557	the C<0> (error) or C<-1> ok.	866	a status of C<0> (ok) or C<-1> (error, see C<$!>).
558		867
559	This is a composite request that tries to rename(2) the file first. If	868	This is a composite request that tries to rename(2) the file first; if
560	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if	869	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
561	that is successful, unlinking the C<$srcpath>.	870	that is successful, unlinks the C<$srcpath>.
562		871
563	=cut	872	=cut
564		873
565	sub aio_move($$;$) {	874	sub aio_move($$;$) {
566	aio_block {
567	my ($src, $dst, $cb) = @_;	875	my ($src, $dst, $cb) = @_;
568		876
569	my $pri = aioreq_pri;	877	my $pri = aioreq_pri;
570	my $grp = aio_group $cb;	878	my $grp = aio_group $cb;
571		879
572	aioreq_pri $pri;	880	aioreq_pri $pri;
573	add $grp aio_rename $src, $dst, sub {	881	add $grp aio_rename $src, $dst, sub {
574	if ($_[0] && $! == EXDEV) {	882	if ($_[0] && $! == EXDEV) {
575	aioreq_pri $pri;	883	aioreq_pri $pri;
576	add $grp aio_copy $src, $dst, sub {	884	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]);	885	$grp->result ($_[0]);
		886
		887	unless ($_[0]) {
		888	aioreq_pri $pri;
		889	add $grp aio_unlink $src;
		890	}
586	}	891	};
		892	} else {
		893	$grp->result ($_[0]);
587	};	894	}
588
589	$grp
590	}	895	};
		896
		897	$grp
591	}	898	}
592		899
593	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	900	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
594		901
595	Scans a directory (similar to C<aio_readdir>) but additionally tries to	902	Scans a directory (similar to C<aio_readdir>) but additionally tries to
…		…
615		922
616	Implementation notes.	923	Implementation notes.
617		924
618	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	925	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
619		926
		927	If readdir returns file type information, then this is used directly to
		928	find directories.
		929
620	After reading the directory, the modification time, size etc. of the	930	Otherwise, after reading the directory, the modification time, size etc.
621	directory before and after the readdir is checked, and if they match (and	931	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	932	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	933	how many entries are directories (if >= 2). Otherwise, no knowledge of the
624	of subdirectories will be assumed.	934	number of subdirectories will be assumed.
625		935
626	Then entries will be sorted into likely directories (everything without	936	Then entries will be sorted into likely directories a non-initial dot
627	a non-initial dot currently) and likely non-directories (everything	937	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,	938	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	939	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	940	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	941	seperately). This is often faster than stat'ing the entry itself because
632	filesystems might detect the type of the entry without reading the inode	942	filesystems might detect the type of the entry without reading the inode
633	data (e.g. ext2fs filetype feature).	943	data (e.g. ext2fs filetype feature), even on systems that cannot return
		944	the filetype information on readdir.
634		945
635	If the known number of directories (link count - 2) has been reached, the	946	If the known number of directories (link count - 2) has been reached, the
636	rest of the entries is assumed to be non-directories.	947	rest of the entries is assumed to be non-directories.
637		948
638	This only works with certainty on POSIX (= UNIX) filesystems, which	949	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
643	directory counting heuristic.	954	directory counting heuristic.
644		955
645	=cut	956	=cut
646		957
647	sub aio_scandir($$;$) {	958	sub aio_scandir($$;$) {
648	aio_block {
649	my ($path, $maxreq, $cb) = @_;	959	my ($path, $maxreq, $cb) = @_;
650		960
651	my $pri = aioreq_pri;	961	my $pri = aioreq_pri;
652		962
653	my $grp = aio_group $cb;	963	my $grp = aio_group $cb;
654		964
655	$maxreq = 4 if $maxreq <= 0;	965	$maxreq = 4 if $maxreq <= 0;
656		966
657	# stat once	967	# stat once
		968	aioreq_pri $pri;
		969	add $grp aio_stat $path, sub {
		970	return $grp->result () if $_[0];
		971	my $now = time;
		972	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		973
		974	# read the directory entries
658	aioreq_pri $pri;	975	aioreq_pri $pri;
659	add $grp aio_stat $path, sub {	976	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
		977	my $entries = shift
660	return $grp->result () if $_[0];	978	or return $grp->result ();
661	my $now = time;
662	my $hash1 = join ":", (stat _)[0,1,3,7,9];
663		979
664	# read the directory entries	980	# stat the dir another time
665	aioreq_pri $pri;	981	aioreq_pri $pri;
666	add $grp aio_readdir $path, sub {
667	my $entries = shift
668	or return $grp->result ();
669
670	# stat the dir another time
671	aioreq_pri $pri;
672	add $grp aio_stat $path, sub {	982	add $grp aio_stat $path, sub {
673	my $hash2 = join ":", (stat _)[0,1,3,7,9];	983	my $hash2 = join ":", (stat _)[0,1,3,7,9];
674		984
675	my $ndirs;	985	my $ndirs;
676		986
677	# take the slow route if anything looks fishy	987	# take the slow route if anything looks fishy
678	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	988	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
679	$ndirs = -1;	989	$ndirs = -1;
680	} else {	990	} else {
681	# if nlink == 2, we are finished	991	# if nlink == 2, we are finished
682	# on non-posix-fs's, we rely on nlink < 2	992	# for non-posix-fs's, we rely on nlink < 2
683	$ndirs = (stat _)[3] - 2	993	$ndirs = (stat _)[3] - 2
684	or return $grp->result ([], $entries);	994	or return $grp->result ([], $entries);
685	}	995	}
686		996
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);	997	my (@dirs, @nondirs);
695		998
696	my $statgrp = add $grp aio_group sub {	999	my $statgrp = add $grp aio_group sub {
697	$grp->result (\@dirs, \@nondirs);	1000	$grp->result (\@dirs, \@nondirs);
698	};	1001	};
699		1002
700	limit $statgrp $maxreq;	1003	limit $statgrp $maxreq;
701	feed $statgrp sub {	1004	feed $statgrp sub {
702	return unless @$entries;	1005	return unless @$entries;
703	my $entry = pop @$entries;	1006	my $entry = shift @$entries;
704		1007
705	aioreq_pri $pri;	1008	aioreq_pri $pri;
706	add $statgrp aio_stat "$path/$entry/.", sub {	1009	add $statgrp aio_stat "$path/$entry/.", sub {
707	if ($_[0] < 0) {	1010	if ($_[0] < 0) {
708	push @nondirs, $entry;	1011	push @nondirs, $entry;
709	} else {	1012	} else {
710	# need to check for real directory	1013	# need to check for real directory
711	aioreq_pri $pri;	1014	aioreq_pri $pri;
712	add $statgrp aio_lstat "$path/$entry", sub {	1015	add $statgrp aio_lstat "$path/$entry", sub {
713	if (-d _) {	1016	if (-d _) {
714	push @dirs, $entry;	1017	push @dirs, $entry;
715		1018
716	unless (--$ndirs) {	1019	unless (--$ndirs) {
717	push @nondirs, @$entries;	1020	push @nondirs, @$entries;
718	feed $statgrp;	1021	feed $statgrp;
719	}
720	} else {
721	push @nondirs, $entry;
722	}	1022	}
		1023	} else {
		1024	push @nondirs, $entry;
723	}	1025	}
724	}	1026	}
725	};	1027	}
726	};	1028	};
727	};	1029	};
728	};	1030	};
729	};	1031	};
730
731	$grp
732	}	1032	};
		1033
		1034	$grp
733	}	1035	}
734		1036
735	=item aio_rmtree $path, $callback->($status)	1037	=item aio_rmtree $path, $callback->($status)
736		1038
737	Delete a directory tree starting (and including) C<$path>, return the	1039	Delete a directory tree starting (and including) C<$path>, return the
…		…
741		1043
742	=cut	1044	=cut
743		1045
744	sub aio_rmtree;	1046	sub aio_rmtree;
745	sub aio_rmtree($;$) {	1047	sub aio_rmtree($;$) {
746	aio_block {
747	my ($path, $cb) = @_;	1048	my ($path, $cb) = @_;
748		1049
749	my $pri = aioreq_pri;	1050	my $pri = aioreq_pri;
750	my $grp = aio_group $cb;	1051	my $grp = aio_group $cb;
751		1052
752	aioreq_pri $pri;	1053	aioreq_pri $pri;
753	add $grp aio_scandir $path, 0, sub {	1054	add $grp aio_scandir $path, 0, sub {
754	my ($dirs, $nondirs) = @_;	1055	my ($dirs, $nondirs) = @_;
755		1056
756	my $dirgrp = aio_group sub {	1057	my $dirgrp = aio_group sub {
757	add $grp aio_rmdir $path, sub {	1058	add $grp aio_rmdir $path, sub {
758	$grp->result ($_[0]);	1059	$grp->result ($_[0]);
759	};
760	};	1060	};
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	};	1061	};
767		1062
768	$grp	1063	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1064	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1065
		1066	add $grp $dirgrp;
769	}	1067	};
		1068
		1069	$grp
770	}	1070	}
		1071
		1072	=item aio_sync $callback->($status)
		1073
		1074	Asynchronously call sync and call the callback when finished.
771		1075
772	=item aio_fsync $fh, $callback->($status)	1076	=item aio_fsync $fh, $callback->($status)
773		1077
774	Asynchronously call fsync on the given filehandle and call the callback	1078	Asynchronously call fsync on the given filehandle and call the callback
775	with the fsync result code.	1079	with the fsync result code.
…		…
779	Asynchronously call fdatasync on the given filehandle and call the	1083	Asynchronously call fdatasync on the given filehandle and call the
780	callback with the fdatasync result code.	1084	callback with the fdatasync result code.
781		1085
782	If this call isn't available because your OS lacks it or it couldn't be	1086	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.	1087	detected, it will be emulated by calling C<fsync> instead.
		1088
		1089	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1090
		1091	Sync the data portion of the file specified by C<$offset> and C<$length>
		1092	to disk (but NOT the metadata), by calling the Linux-specific
		1093	sync_file_range call. If sync_file_range is not available or it returns
		1094	ENOSYS, then fdatasync or fsync is being substituted.
		1095
		1096	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1097	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1098	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1099	manpage for details.
		1100
		1101	=item aio_pathsync $path, $callback->($status)
		1102
		1103	This request tries to open, fsync and close the given path. This is a
		1104	composite request intended to sync directories after directory operations
		1105	(E.g. rename). This might not work on all operating systems or have any
		1106	specific effect, but usually it makes sure that directory changes get
		1107	written to disc. It works for anything that can be opened for read-only,
		1108	not just directories.
		1109
		1110	Future versions of this function might fall back to other methods when
		1111	C<fsync> on the directory fails (such as calling C<sync>).
		1112
		1113	Passes C<0> when everything went ok, and C<-1> on error.
		1114
		1115	=cut
		1116
		1117	sub aio_pathsync($;$) {
		1118	my ($path, $cb) = @_;
		1119
		1120	my $pri = aioreq_pri;
		1121	my $grp = aio_group $cb;
		1122
		1123	aioreq_pri $pri;
		1124	add $grp aio_open $path, O_RDONLY, 0, sub {
		1125	my ($fh) = @_;
		1126	if ($fh) {
		1127	aioreq_pri $pri;
		1128	add $grp aio_fsync $fh, sub {
		1129	$grp->result ($_[0]);
		1130
		1131	aioreq_pri $pri;
		1132	add $grp aio_close $fh;
		1133	};
		1134	} else {
		1135	$grp->result (-1);
		1136	}
		1137	};
		1138
		1139	$grp
		1140	}
		1141
		1142	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1143
		1144	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1145	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1146	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1147	scalar must only be modified in-place while an aio operation is pending on
		1148	it).
		1149
		1150	It calls the C<msync> function of your OS, if available, with the memory
		1151	area starting at C<$offset> in the string and ending C<$length> bytes
		1152	later. If C<$length> is negative, counts from the end, and if C<$length>
		1153	is C<undef>, then it goes till the end of the string. The flags can be
		1154	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1155	C<IO::AIO::MS_SYNC>.
		1156
		1157	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1158
		1159	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1160	scalars.
		1161
		1162	It touches (reads or writes) all memory pages in the specified
		1163	range inside the scalar. All caveats and parameters are the same
		1164	as for C<aio_msync>, above, except for flags, which must be either
		1165	C<0> (which reads all pages and ensures they are instantiated) or
		1166	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1167	writing an octet from it, which dirties the page).
		1168
		1169	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1170
		1171	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1172	scalars.
		1173
		1174	It reads in all the pages of the underlying storage into memory (if any)
		1175	and locks them, so they are not getting swapped/paged out or removed.
		1176
		1177	If C<$length> is undefined, then the scalar will be locked till the end.
		1178
		1179	On systems that do not implement C<mlock>, this function returns C<-1>
		1180	and sets errno to C<ENOSYS>.
		1181
		1182	Note that the corresponding C<munlock> is synchronous and is
		1183	documented under L<MISCELLANEOUS FUNCTIONS>.
		1184
		1185	Example: open a file, mmap and mlock it - both will be undone when
		1186	C<$data> gets destroyed.
		1187
		1188	open my $fh, "<", $path or die "$path: $!";
		1189	my $data;
		1190	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1191	aio_mlock $data; # mlock in background
		1192
		1193	=item aio_mlockall $flags, $callback->($status)
		1194
		1195	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1196	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1197
		1198	On systems that do not implement C<mlockall>, this function returns C<-1>
		1199	and sets errno to C<ENOSYS>.
		1200
		1201	Note that the corresponding C<munlockall> is synchronous and is
		1202	documented under L<MISCELLANEOUS FUNCTIONS>.
		1203
		1204	Example: asynchronously lock all current and future pages into memory.
		1205
		1206	aio_mlockall IO::AIO::MCL_FUTURE;
784		1207
785	=item aio_group $callback->(...)	1208	=item aio_group $callback->(...)
786		1209
787	This is a very special aio request: Instead of doing something, it is a	1210	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	1211	container for other aio requests, which is useful if you want to bundle
…		…
838	=item cancel $req	1261	=item cancel $req
839		1262
840	Cancels the request, if possible. Has the effect of skipping execution	1263	Cancels the request, if possible. Has the effect of skipping execution
841	when entering the B<execute> state and skipping calling the callback when	1264	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	1265	entering the the B<result> state, but will leave the request otherwise
843	untouched. That means that requests that currently execute will not be	1266	untouched (with the exception of readdir). That means that requests that
844	stopped and resources held by the request will not be freed prematurely.	1267	currently execute will not be stopped and resources held by the request
		1268	will not be freed prematurely.
845		1269
846	=item cb $req $callback->(...)	1270	=item cb $req $callback->(...)
847		1271
848	Replace (or simply set) the callback registered to the request.	1272	Replace (or simply set) the callback registered to the request.
849		1273
…		…
900	Their lifetime, simplified, looks like this: when they are empty, they	1324	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	1325	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	1326	C<done> state, they will also finish. Otherwise they will continue to
903	exist.	1327	exist.
904		1328
905	That means after creating a group you have some time to add requests. And	1329	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	1330	(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	1331	the C<poll_cb>). And in the callbacks of those requests, you can add
908	itself finish.	1332	further requests to the group. And only when all those requests have
		1333	finished will the the group itself finish.
909		1334
910	=over 4	1335	=over 4
911		1336
912	=item add $grp ...	1337	=item add $grp ...
913		1338
…		…
922	=item $grp->cancel_subs	1347	=item $grp->cancel_subs
923		1348
924	Cancel all subrequests and clears any feeder, but not the group request	1349	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.	1350	itself. Useful when you queued a lot of events but got a result early.
926		1351
		1352	The group request will finish normally (you cannot add requests to the
		1353	group).
		1354
927	=item $grp->result (...)	1355	=item $grp->result (...)
928		1356
929	Set the result value(s) that will be passed to the group callback when all	1357	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	1358	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,	1359	of errno (just like calling C<errno> without an error number). By default,
932	no argument will be passed and errno is zero.	1360	no argument will be passed and errno is zero.
933		1361
934	=item $grp->errno ([$errno])	1362	=item $grp->errno ([$errno])
935		1363
…		…
946	=item feed $grp $callback->($grp)	1374	=item feed $grp $callback->($grp)
947		1375
948	Sets a feeder/generator on this group: every group can have an attached	1376	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,	1377	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,	1378	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	1379	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>	1380	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
953	requests, delaying any later requests for a long time.	1381	delaying any later requests for a long time.
954		1382
955	To avoid this, and allow incremental generation of requests, you can	1383	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	1384	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>,	1385	feed callback will be called whenever there are few enough (see C<limit>,
958	below) requests active in the group itself and is expected to queue more	1386	below) requests active in the group itself and is expected to queue more
…		…
962	not impose any limits).	1390	not impose any limits).
963		1391
964	If the feed does not queue more requests when called, it will be	1392	If the feed does not queue more requests when called, it will be
965	automatically removed from the group.	1393	automatically removed from the group.
966		1394
967	If the feed limit is C<0>, it will be set to C<2> automatically.	1395	If the feed limit is C<0> when this method is called, it will be set to
		1396	C<2> automatically.
968		1397
969	Example:	1398	Example:
970		1399
971	# stat all files in @files, but only ever use four aio requests concurrently:	1400	# stat all files in @files, but only ever use four aio requests concurrently:
972		1401
…		…
984	Sets the feeder limit for the group: The feeder will be called whenever	1413	Sets the feeder limit for the group: The feeder will be called whenever
985	the group contains less than this many requests.	1414	the group contains less than this many requests.
986		1415
987	Setting the limit to C<0> will pause the feeding process.	1416	Setting the limit to C<0> will pause the feeding process.
988		1417
		1418	The default value for the limit is C<0>, but note that setting a feeder
		1419	automatically bumps it up to C<2>.
		1420
989	=back	1421	=back
990		1422
991	=head2 SUPPORT FUNCTIONS	1423	=head2 SUPPORT FUNCTIONS
992		1424
993	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1425	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
…		…
995	=over 4	1427	=over 4
996		1428
997	=item $fileno = IO::AIO::poll_fileno	1429	=item $fileno = IO::AIO::poll_fileno
998		1430
999	Return the I<request result pipe file descriptor>. This filehandle must be	1431	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	1432	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	1433	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1002	to call C<poll_cb> to check the results.	1434	you have to call C<poll_cb> to check the results.
1003		1435
1004	See C<poll_cb> for an example.	1436	See C<poll_cb> for an example.
1005		1437
1006	=item IO::AIO::poll_cb	1438	=item IO::AIO::poll_cb
1007		1439
1008	Process some outstanding events on the result pipe. You have to call this	1440	Process some outstanding events on the result pipe. You have to call
1009	regularly. Returns the number of events processed. Returns immediately	1441	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	1442	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>.	1443	reason. Returns immediately when no events are outstanding. The amount of
		1444	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1445	C<IO::AIO::max_poll_time>.
1012		1446
1013	If not all requests were processed for whatever reason, the filehandle	1447	If not all requests were processed for whatever reason, the filehandle
1014	will still be ready when C<poll_cb> returns.	1448	will still be ready when C<poll_cb> returns, so normally you don't have to
		1449	do anything special to have it called later.
		1450
		1451	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1452	ready, it can be beneficial to call this function from loops which submit
		1453	a lot of requests, to make sure the results get processed when they become
		1454	available and not just when the loop is finished and the event loop takes
		1455	over again. This function returns very fast when there are no outstanding
		1456	requests.
1015		1457
1016	Example: Install an Event watcher that automatically calls	1458	Example: Install an Event watcher that automatically calls
1017	IO::AIO::poll_cb with high priority:	1459	IO::AIO::poll_cb with high priority (more examples can be found in the
		1460	SYNOPSIS section, at the top of this document):
1018		1461
1019	Event->io (fd => IO::AIO::poll_fileno,	1462	Event->io (fd => IO::AIO::poll_fileno,
1020	poll => 'r', async => 1,	1463	poll => 'r', async => 1,
1021	cb => \&IO::AIO::poll_cb);	1464	cb => \&IO::AIO::poll_cb);
		1465
		1466	=item IO::AIO::poll_wait
		1467
		1468	If there are any outstanding requests and none of them in the result
		1469	phase, wait till the result filehandle becomes ready for reading (simply
		1470	does a C<select> on the filehandle. This is useful if you want to
		1471	synchronously wait for some requests to finish).
		1472
		1473	See C<nreqs> for an example.
		1474
		1475	=item IO::AIO::poll
		1476
		1477	Waits until some requests have been handled.
		1478
		1479	Returns the number of requests processed, but is otherwise strictly
		1480	equivalent to:
		1481
		1482	IO::AIO::poll_wait, IO::AIO::poll_cb
		1483
		1484	=item IO::AIO::flush
		1485
		1486	Wait till all outstanding AIO requests have been handled.
		1487
		1488	Strictly equivalent to:
		1489
		1490	IO::AIO::poll_wait, IO::AIO::poll_cb
		1491	while IO::AIO::nreqs;
1022		1492
1023	=item IO::AIO::max_poll_reqs $nreqs	1493	=item IO::AIO::max_poll_reqs $nreqs
1024		1494
1025	=item IO::AIO::max_poll_time $seconds	1495	=item IO::AIO::max_poll_time $seconds
1026		1496
…		…
1051	# use a low priority so other tasks have priority	1521	# use a low priority so other tasks have priority
1052	Event->io (fd => IO::AIO::poll_fileno,	1522	Event->io (fd => IO::AIO::poll_fileno,
1053	poll => 'r', nice => 1,	1523	poll => 'r', nice => 1,
1054	cb => &IO::AIO::poll_cb);	1524	cb => &IO::AIO::poll_cb);
1055		1525
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	1526	=back
1084		1527
1085	=head3 CONTROLLING THE NUMBER OF THREADS	1528	=head3 CONTROLLING THE NUMBER OF THREADS
1086		1529
1087	=over	1530	=over
…		…
1120		1563
1121	Under normal circumstances you don't need to call this function.	1564	Under normal circumstances you don't need to call this function.
1122		1565
1123	=item IO::AIO::max_idle $nthreads	1566	=item IO::AIO::max_idle $nthreads
1124		1567
1125	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1568	Limit the number of threads (default: 4) that are allowed to idle
1126	threads that did not get a request to process within 10 seconds). That	1569	(i.e., threads that did not get a request to process within the idle
1127	means if a thread becomes idle while C<$nthreads> other threads are also	1570	timeout (default: 10 seconds). That means if a thread becomes idle while
1128	idle, it will free its resources and exit.	1571	C<$nthreads> other threads are also idle, it will free its resources and
		1572	exit.
1129		1573
1130	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1574	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	1575	to allow for extremely high load situations, but want to free resources
1132	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1576	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1133		1577
1134	The default is probably ok in most situations, especially if thread	1578	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	1579	creation is fast. If thread creation is very slow on your system you might
1136	want to use larger values.	1580	want to use larger values.
1137		1581
		1582	=item IO::AIO::idle_timeout $seconds
		1583
		1584	Sets the minimum idle timeout (default 10) after which worker threads are
		1585	allowed to exit. SEe C<IO::AIO::max_idle>.
		1586
1138	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1587	=item IO::AIO::max_outstanding $maxreqs
		1588
		1589	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1590	you do queue up more than this number of requests, the next call to
		1591	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1592	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1593	longer exceeded.
		1594
		1595	In other words, this setting does not enforce a queue limit, but can be
		1596	used to make poll functions block if the limit is exceeded.
1139		1597
1140	This is a very bad function to use in interactive programs because it	1598	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	1599	blocks, and a bad way to reduce concurrency because it is inexact: Better
1142	use an C<aio_group> together with a feed callback.	1600	use an C<aio_group> together with a feed callback.
1143		1601
1144	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1602	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	1603	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		1604
1149	The default value is very large, so there is no practical limit on the	1605	IO::AIO::max_outstanding 32;
1150	number of outstanding requests.
1151		1606
1152	You can still queue as many requests as you want. Therefore,	1607	for my $path (...) {
1153	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	1608	aio_stat $path , ...;
1154	as a stop gap to shield against fatal memory overflow (with large values).	1609	IO::AIO::poll_cb;
		1610	}
		1611
		1612	IO::AIO::flush;
		1613
		1614	The call to C<poll_cb> inside the loop will normally return instantly, but
		1615	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1616	some requests have been handled. This keeps the loop from pushing a large
		1617	number of C<aio_stat> requests onto the queue.
		1618
		1619	The default value for C<max_outstanding> is very large, so there is no
		1620	practical limit on the number of outstanding requests.
1155		1621
1156	=back	1622	=back
1157		1623
1158	=head3 STATISTICAL INFORMATION	1624	=head3 STATISTICAL INFORMATION
1159		1625
…		…
1179	Returns the number of requests currently in the pending state (executed,	1645	Returns the number of requests currently in the pending state (executed,
1180	but not yet processed by poll_cb).	1646	but not yet processed by poll_cb).
1181		1647
1182	=back	1648	=back
1183		1649
		1650	=head3 MISCELLANEOUS FUNCTIONS
		1651
		1652	IO::AIO implements some functions that might be useful, but are not
		1653	asynchronous.
		1654
		1655	=over 4
		1656
		1657	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1658
		1659	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1660	but is blocking (this makes most sense if you know the input data is
		1661	likely cached already and the output filehandle is set to non-blocking
		1662	operations).
		1663
		1664	Returns the number of bytes copied, or C<-1> on error.
		1665
		1666	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1667
		1668	Simply calls the C<posix_fadvise> function (see its
		1669	manpage for details). The following advice constants are
		1670	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1671	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1672	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1673
		1674	On systems that do not implement C<posix_fadvise>, this function returns
		1675	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1676
		1677	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1678
		1679	Simply calls the C<posix_madvise> function (see its
		1680	manpage for details). The following advice constants are
		1681	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1682	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1683
		1684	On systems that do not implement C<posix_madvise>, this function returns
		1685	ENOSYS, otherwise the return value of C<posix_madvise>.
		1686
		1687	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1688
		1689	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1690	$scalar (see its manpage for details). The following protect
		1691	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1692	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1693
		1694	On systems that do not implement C<mprotect>, this function returns
		1695	ENOSYS, otherwise the return value of C<mprotect>.
		1696
		1697	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1698
		1699	Memory-maps a file (or anonymous memory range) and attaches it to the
		1700	given C<$scalar>, which will act like a string scalar.
		1701
		1702	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1703	change the string length, and most read-only operations such as copying it
		1704	or searching it with regexes and so on.
		1705
		1706	Anything else is unsafe and will, at best, result in memory leaks.
		1707
		1708	The memory map associated with the C<$scalar> is automatically removed
		1709	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1710	C<IO::AIO::munmap> functions are called.
		1711
		1712	This calls the C<mmap>(2) function internally. See your system's manual
		1713	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1714
		1715	The C<$length> must be larger than zero and smaller than the actual
		1716	filesize.
		1717
		1718	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1719	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1720
		1721	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1722	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1723	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1724	(which is set to C<MAP_ANON> if your system only provides this
		1725	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1726	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1727	C<IO::AIO::MAP_NONBLOCK>
		1728
		1729	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1730
		1731	C<$offset> is the offset from the start of the file - it generally must be
		1732	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1733
		1734	Example:
		1735
		1736	use Digest::MD5;
		1737	use IO::AIO;
		1738
		1739	open my $fh, "<verybigfile"
		1740	or die "$!";
		1741
		1742	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1743	or die "verybigfile: $!";
		1744
		1745	my $fast_md5 = md5 $data;
		1746
		1747	=item IO::AIO::munmap $scalar
		1748
		1749	Removes a previous mmap and undefines the C<$scalar>.
		1750
		1751	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1752
		1753	Calls the C<munlock> function, undoing the effects of a previous
		1754	C<aio_mlock> call (see its description for details).
		1755
		1756	=item IO::AIO::munlockall
		1757
		1758	Calls the C<munlockall> function.
		1759
		1760	On systems that do not implement C<munlockall>, this function returns
		1761	ENOSYS, otherwise the return value of C<munlockall>.
		1762
		1763	=back
		1764
1184	=cut	1765	=cut
1185		1766
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;	1767	min_parallel 8;
1203		1768
1204	END { flush }	1769	END { flush }
1205		1770
1206	1;	1771	1;
1207		1772
		1773	=head1 EVENT LOOP INTEGRATION
		1774
		1775	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1776	automatically into many event loops:
		1777
		1778	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1779	use AnyEvent::AIO;
		1780
		1781	You can also integrate IO::AIO manually into many event loops, here are
		1782	some examples of how to do this:
		1783
		1784	# EV integration
		1785	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1786
		1787	# Event integration
		1788	Event->io (fd => IO::AIO::poll_fileno,
		1789	poll => 'r',
		1790	cb => \&IO::AIO::poll_cb);
		1791
		1792	# Glib/Gtk2 integration
		1793	add_watch Glib::IO IO::AIO::poll_fileno,
		1794	in => sub { IO::AIO::poll_cb; 1 };
		1795
		1796	# Tk integration
		1797	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1798	readable => \&IO::AIO::poll_cb);
		1799
		1800	# Danga::Socket integration
		1801	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1802	\&IO::AIO::poll_cb);
		1803
1208	=head2 FORK BEHAVIOUR	1804	=head2 FORK BEHAVIOUR
1209		1805
1210	This module should do "the right thing" when the process using it forks:	1806	Usage of pthreads in a program changes the semantics of fork
		1807	considerably. Specifically, only async-safe functions can be called after
		1808	fork. Perl doesn't know about this, so in general, you cannot call fork
		1809	with defined behaviour in perl. IO::AIO uses pthreads, so this applies,
		1810	but many other extensions and (for inexplicable reasons) perl itself often
		1811	is linked against pthreads, so this limitation applies.
1211		1812
1212	Before the fork, IO::AIO enters a quiescent state where no requests	1813	Some operating systems have extensions that allow safe use of fork, and
1213	can be added in other threads and no results will be processed. After	1814	this module should do "the right thing" on those, and tries on others. At
1214	the fork the parent simply leaves the quiescent state and continues	1815	the time of this writing (2011) only GNU/Linux supports these extensions
1215	request/result processing, while the child frees the request/result queue	1816	to POSIX.
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
1220	In short: the parent will, after a short pause, continue as if fork had
1221	not been called, while the child will act as if IO::AIO has not been used
1222	yet.
1223		1817
1224	=head2 MEMORY USAGE	1818	=head2 MEMORY USAGE
1225		1819
1226	Per-request usage:	1820	Per-request usage:
1227		1821
…		…
1229	bytes of memory. In addition, stat requests need a stat buffer (possibly	1823	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	1824	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	1825	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.	1826	will consume memory till the request has entered the done state.
1233		1827
1234	This is now awfully much, so queuing lots of requests is not usually a	1828	This is not awfully much, so queuing lots of requests is not usually a
1235	problem.	1829	problem.
1236		1830
1237	Per-thread usage:	1831	Per-thread usage:
1238		1832
1239	In the execution phase, some aio requests require more memory for	1833	In the execution phase, some aio requests require more memory for
…		…
1244		1838
1245	Known bugs will be fixed in the next release.	1839	Known bugs will be fixed in the next release.
1246		1840
1247	=head1 SEE ALSO	1841	=head1 SEE ALSO
1248		1842
1249	L<Coro::AIO>.	1843	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1844	more natural syntax.
1250		1845
1251	=head1 AUTHOR	1846	=head1 AUTHOR
1252		1847
1253	Marc Lehmann <schmorp@schmorp.de>	1848	Marc Lehmann <schmorp@schmorp.de>
1254	http://home.schmorp.de/	1849	http://home.schmorp.de/

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