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Revision 1.104 by root, Sat Mar 24 19:19:11 2007 UTC vs.
Revision 1.208 by root, Mon Sep 26 20:19:08 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
		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 $path, $mode, $dev, $callback->($status)
		227	aio_link $srcpath, $dstpath, $callback->($status)
		228	aio_symlink $srcpath, $dstpath, $callback->($status)
		229	aio_readlink $path, $callback->($link)
		230	aio_realpath $path, $callback->($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 $path, $data, $callback->($status)
		239	aio_copy $srcpath, $dstpath, $callback->($status)
		240	aio_move $srcpath, $dstpath, $callback->($status)
		241	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		242	aio_rmtree $path, $callback->($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 $path, $callback->($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, $length = undef
		279	IO::AIO::munlockall
214		280
215	=head2 AIO REQUEST FUNCTIONS	281	=head2 AIO REQUEST FUNCTIONS
216		282
217	All the C<aio_*> calls are more or less thin wrappers around the syscall	283	All the C<aio_*> calls are more or less thin wrappers around the syscall
218	with the same name (sans C<aio_>). The arguments are similar or identical,	284	with the same name (sans C<aio_>). The arguments are similar or identical,
219	and they all accept an additional (and optional) C<$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 get called with
221	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	287	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	288	perl, which usually delivers "false") as its sole argument after the given
223	syscall has been executed asynchronously.	289	syscall has been executed asynchronously.
224		290
225	All functions expecting a filehandle keep a copy of the filehandle	291	All functions expecting a filehandle keep a copy of the filehandle
226	internally until the request has finished.	292	internally until the request has finished.
227		293
…		…
241	your pathnames to the locale (or other) encoding in effect in the user	307	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)	308	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
243	use something else to ensure your scalar has the correct contents.	309	use something else to ensure your scalar has the correct contents.
244		310
245	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	311	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
246	handles correctly wether it is set or not.	312	handles correctly whether it is set or not.
247		313
248	=over 4	314	=over 4
249		315
250	=item $prev_pri = aioreq_pri [$pri]	316	=item $prev_pri = aioreq_pri [$pri]
251		317
…		…
271	aio_read $_[0], ..., sub {	337	aio_read $_[0], ..., sub {
272	...	338	...
273	};	339	};
274	};	340	};
275		341
		342
276	=item aioreq_nice $pri_adjust	343	=item aioreq_nice $pri_adjust
277		344
278	Similar to C<aioreq_pri>, but subtracts the given value from the current	345	Similar to C<aioreq_pri>, but subtracts the given value from the current
279	priority, so the effect is cumulative.	346	priority, so the effect is cumulative.
		347
280		348
281	=item aio_open $pathname, $flags, $mode, $callback->($fh)	349	=item aio_open $pathname, $flags, $mode, $callback->($fh)
282		350
283	Asynchronously open or create a file and call the callback with a newly	351	Asynchronously open or create a file and call the callback with a newly
284	created filehandle for the file.	352	created filehandle for the file.
…		…
296	by the umask in effect then the request is being executed, so better never	364	by the umask in effect then the request is being executed, so better never
297	change the umask.	365	change the umask.
298		366
299	Example:	367	Example:
300		368
301	aio_open "/etc/passwd", O_RDONLY, 0, sub {	369	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
302	if ($_[0]) {	370	if ($_[0]) {
303	print "open successful, fh is $_[0]\n";	371	print "open successful, fh is $_[0]\n";
304	...	372	...
305	} else {	373	} else {
306	die "open failed: $!\n";	374	die "open failed: $!\n";
307	}	375	}
308	};	376	};
309		377
		378	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		379	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		380	following POSIX and non-POSIX constants are available (missing ones on
		381	your system are, as usual, C<0>):
		382
		383	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		384	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		385	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		386
		387
310	=item aio_close $fh, $callback->($status)	388	=item aio_close $fh, $callback->($status)
311		389
312	Asynchronously close a file and call the callback with the result	390	Asynchronously close a file and call the callback with the result
313	code. I<WARNING:> although accepted, you should not pass in a perl	391	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		392
318	This is supposed to be a bug in the API, so that might change. It's	393	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
319	therefore best to avoid this function.	394	closing the file descriptor associated with the filehandle itself.
		395
		396	Therefore, C<aio_close> will not close the filehandle - instead it will
		397	use dup2 to overwrite the file descriptor with the write-end of a pipe
		398	(the pipe fd will be created on demand and will be cached).
		399
		400	Or in other words: the file descriptor will be closed, but it will not be
		401	free for reuse until the perl filehandle is closed.
		402
		403	=cut
320		404
321	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	405	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
322		406
323	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	407	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
324		408
325	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	409	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	410	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
327	callback without the actual number of bytes read (or -1 on error, just	411	and calls the callback without the actual number of bytes read (or -1 on
328	like the syscall).	412	error, just like the syscall).
		413
		414	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		415	offset plus the actual number of bytes read.
		416
		417	If C<$offset> is undefined, then the current file descriptor offset will
		418	be used (and updated), otherwise the file descriptor offset will not be
		419	changed by these calls.
		420
		421	If C<$length> is undefined in C<aio_write>, use the remaining length of
		422	C<$data>.
		423
		424	If C<$dataoffset> is less than zero, it will be counted from the end of
		425	C<$data>.
329		426
330	The C<$data> scalar I<MUST NOT> be modified in any way while the request	427	The C<$data> scalar I<MUST NOT> be modified in any way while the request
331	is outstanding. Modifying it can result in segfaults or WW3 (if the	428	is outstanding. Modifying it can result in segfaults or World War III (if
332	necessary/optional hardware is installed).	429	the necessary/optional hardware is installed).
333		430
334	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	431	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
335	offset C<0> within the scalar:	432	offset C<0> within the scalar:
336		433
337	aio_read $fh, 7, 15, $buffer, 0, sub {	434	aio_read $fh, 7, 15, $buffer, 0, sub {
338	$_[0] > 0 or die "read error: $!";	435	$_[0] > 0 or die "read error: $!";
339	print "read $_[0] bytes: <$buffer>\n";	436	print "read $_[0] bytes: <$buffer>\n";
340	};	437	};
341		438
		439
342	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	440	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
343		441
344	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	442	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
345	reading at byte offset C<$in_offset>, and starts writing at the current	443	reading at byte offset C<$in_offset>, and starts writing at the current
346	file offset of C<$out_fh>. Because of that, it is not safe to issue more	444	file offset of C<$out_fh>. Because of that, it is not safe to issue more
347	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	445	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
348	other.	446	other. The same C<$in_fh> works fine though, as this function does not
		447	move or use the file offset of C<$in_fh>.
349		448
		449	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		450	are written, and there is no way to find out how many more bytes have been
		451	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		452	number of bytes written to C<$out_fh>. Only if the result value equals
		453	C<$length> one can assume that C<$length> bytes have been read.
		454
		455	Unlike with other C<aio_> functions, it makes a lot of sense to use
		456	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		457	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		458	the socket I/O will be non-blocking. Note, however, that you can run
		459	into a trap where C<aio_sendfile> reads some data with readahead, then
		460	fails to write all data, and when the socket is ready the next time, the
		461	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		462	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		463	resource usage.
		464
350	This call tries to make use of a native C<sendfile> syscall to provide	465	This call tries to make use of a native C<sendfile>-like syscall to
351	zero-copy operation. For this to work, C<$out_fh> should refer to a	466	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.	467	a socket, and C<$in_fh> should refer to an mmap'able file.
353		468
354	If the native sendfile call fails or is not implemented, it will be	469	If a native sendfile cannot be found or it fails with C<ENOSYS>,
355	emulated, so you can call C<aio_sendfile> on any type of filehandle	470	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		471	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
356	regardless of the limitations of the operating system.	472	type of filehandle regardless of the limitations of the operating system.
357		473
358	Please note, however, that C<aio_sendfile> can read more bytes from	474	As native sendfile syscalls (as practically any non-POSIX interface hacked
359	C<$in_fh> than are written, and there is no way to find out how many	475	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	476	on many systems, this implementation tries to work around some known bugs
361	provides the number of bytes written to C<$out_fh>. Only if the result	477	in Linux and FreeBSD kernels (probably others, too), but that might fail,
362	value equals C<$length> one can assume that C<$length> bytes have been	478	so you really really should check the return value of C<aio_sendfile> -
363	read.	479	fewre bytes than expected might have been transferred.
		480
364		481
365	=item aio_readahead $fh,$offset,$length, $callback->($retval)	482	=item aio_readahead $fh,$offset,$length, $callback->($retval)
366		483
367	C<aio_readahead> populates the page cache with data from a file so that	484	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<$offset>	485	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
374	file. The current file offset of the file is left unchanged.	491	file. The current file offset of the file is left unchanged.
375		492
376	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	493	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.	494	emulated by simply reading the data, which would have a similar effect.
378		495
		496
379	=item aio_stat $fh_or_path, $callback->($status)	497	=item aio_stat $fh_or_path, $callback->($status)
380		498
381	=item aio_lstat $fh, $callback->($status)	499	=item aio_lstat $fh, $callback->($status)
382		500
383	Works like perl's C<stat> or C<lstat> in void context. The callback will	501	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
388	for an explanation.	506	for an explanation.
389		507
390	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	508	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	509	error when stat'ing a large file, the results will be silently truncated
392	unless perl itself is compiled with large file support.	510	unless perl itself is compiled with large file support.
		511
		512	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		513	following constants and functions (if not implemented, the constants will
		514	be C<0> and the functions will either C<croak> or fall back on traditional
		515	behaviour).
		516
		517	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		518	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		519	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
393		520
394	Example: Print the length of F</etc/passwd>:	521	Example: Print the length of F</etc/passwd>:
395		522
396	aio_stat "/etc/passwd", sub {	523	aio_stat "/etc/passwd", sub {
397	$_[0] and die "stat failed: $!";	524	$_[0] and die "stat failed: $!";
398	print "size is ", -s _, "\n";	525	print "size is ", -s _, "\n";
399	};	526	};
400		527
		528
		529	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		530
		531	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		532	whether a file handle or path was passed.
		533
		534	On success, the callback is passed a hash reference with the following
		535	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		536	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		537	is passed.
		538
		539	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		540	C<ST_NOSUID>.
		541
		542	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		543	their correct value when available, or to C<0> on systems that do
		544	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		545	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		546	C<ST_NODIRATIME> and C<ST_RELATIME>.
		547
		548	Example: stat C</wd> and dump out the data if successful.
		549
		550	aio_statvfs "/wd", sub {
		551	my $f = $_[0]
		552	or die "statvfs: $!";
		553
		554	use Data::Dumper;
		555	say Dumper $f;
		556	};
		557
		558	# result:
		559	{
		560	bsize => 1024,
		561	bfree => 4333064312,
		562	blocks => 10253828096,
		563	files => 2050765568,
		564	flag => 4096,
		565	favail => 2042092649,
		566	bavail => 4333064312,
		567	ffree => 2042092649,
		568	namemax => 255,
		569	frsize => 1024,
		570	fsid => 1810
		571	}
		572
		573
		574	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		575
		576	Works like perl's C<utime> function (including the special case of $atime
		577	and $mtime being undef). Fractional times are supported if the underlying
		578	syscalls support them.
		579
		580	When called with a pathname, uses utimes(2) if available, otherwise
		581	utime(2). If called on a file descriptor, uses futimes(2) if available,
		582	otherwise returns ENOSYS, so this is not portable.
		583
		584	Examples:
		585
		586	# set atime and mtime to current time (basically touch(1)):
		587	aio_utime "path", undef, undef;
		588	# set atime to current time and mtime to beginning of the epoch:
		589	aio_utime "path", time, undef; # undef==0
		590
		591
		592	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		593
		594	Works like perl's C<chown> function, except that C<undef> for either $uid
		595	or $gid is being interpreted as "do not change" (but -1 can also be used).
		596
		597	Examples:
		598
		599	# same as "chown root path" in the shell:
		600	aio_chown "path", 0, -1;
		601	# same as above:
		602	aio_chown "path", 0, undef;
		603
		604
		605	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		606
		607	Works like truncate(2) or ftruncate(2).
		608
		609
		610	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		611
		612	Works like perl's C<chmod> function.
		613
		614
401	=item aio_unlink $pathname, $callback->($status)	615	=item aio_unlink $pathname, $callback->($status)
402		616
403	Asynchronously unlink (delete) a file and call the callback with the	617	Asynchronously unlink (delete) a file and call the callback with the
404	result code.	618	result code.
405		619
		620
406	=item aio_mknod $path, $mode, $dev, $callback->($status)	621	=item aio_mknod $path, $mode, $dev, $callback->($status)
407		622
408	[EXPERIMENTAL]	623	[EXPERIMENTAL]
409		624
410	Asynchronously create a device node (or fifo). See mknod(2).	625	Asynchronously create a device node (or fifo). See mknod(2).
411		626
412	The only (POSIX-) portable way of calling this function is:	627	The only (POSIX-) portable way of calling this function is:
413		628
414	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	629	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		630
		631	See C<aio_stat> for info about some potentially helpful extra constants
		632	and functions.
415		633
416	=item aio_link $srcpath, $dstpath, $callback->($status)	634	=item aio_link $srcpath, $dstpath, $callback->($status)
417		635
418	Asynchronously create a new link to the existing object at C<$srcpath> at	636	Asynchronously create a new link to the existing object at C<$srcpath> at
419	the path C<$dstpath> and call the callback with the result code.	637	the path C<$dstpath> and call the callback with the result code.
420		638
		639
421	=item aio_symlink $srcpath, $dstpath, $callback->($status)	640	=item aio_symlink $srcpath, $dstpath, $callback->($status)
422		641
423	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	642	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
424	the path C<$dstpath> and call the callback with the result code.	643	the path C<$dstpath> and call the callback with the result code.
		644
425		645
426	=item aio_readlink $path, $callback->($link)	646	=item aio_readlink $path, $callback->($link)
427		647
428	Asynchronously read the symlink specified by C<$path> and pass it to	648	Asynchronously read the symlink specified by C<$path> and pass it to
429	the callback. If an error occurs, nothing or undef gets passed to the	649	the callback. If an error occurs, nothing or undef gets passed to the
430	callback.	650	callback.
431		651
		652
		653	=item aio_realpath $path, $callback->($path)
		654
		655	Asynchronously make the path absolute and resolve any symlinks in
		656	C<$path>. The resulting path only consists of directories (Same as
		657	L<Cwd::realpath>).
		658
		659	This request can be used to get the absolute path of the current working
		660	directory by passing it a path of F<.> (a single dot).
		661
		662
432	=item aio_rename $srcpath, $dstpath, $callback->($status)	663	=item aio_rename $srcpath, $dstpath, $callback->($status)
433		664
434	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	665	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
435	rename(2) and call the callback with the result code.	666	rename(2) and call the callback with the result code.
		667
436		668
437	=item aio_mkdir $pathname, $mode, $callback->($status)	669	=item aio_mkdir $pathname, $mode, $callback->($status)
438		670
439	Asynchronously mkdir (create) a directory and call the callback with	671	Asynchronously mkdir (create) a directory and call the callback with
440	the result code. C<$mode> will be modified by the umask at the time the	672	the result code. C<$mode> will be modified by the umask at the time the
441	request is executed, so do not change your umask.	673	request is executed, so do not change your umask.
442		674
		675
443	=item aio_rmdir $pathname, $callback->($status)	676	=item aio_rmdir $pathname, $callback->($status)
444		677
445	Asynchronously rmdir (delete) a directory and call the callback with the	678	Asynchronously rmdir (delete) a directory and call the callback with the
446	result code.	679	result code.
		680
447		681
448	=item aio_readdir $pathname, $callback->($entries)	682	=item aio_readdir $pathname, $callback->($entries)
449		683
450	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	684	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	685	directory (i.e. opendir + readdir + closedir). The entries will not be
452	sorted, and will B<NOT> include the C<.> and C<..> entries.	686	sorted, and will B<NOT> include the C<.> and C<..> entries.
453		687
454	The callback a single argument which is either C<undef> or an array-ref	688	The callback is passed a single argument which is either C<undef> or an
455	with the filenames.	689	array-ref with the filenames.
		690
		691
		692	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		693
		694	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
		695	tune behaviour and output format. In case of an error, C<$entries> will be
		696	C<undef>.
		697
		698	The flags are a combination of the following constants, ORed together (the
		699	flags will also be passed to the callback, possibly modified):
		700
		701	=over 4
		702
		703	=item IO::AIO::READDIR_DENTS
		704
		705	When this flag is off, then the callback gets an arrayref consisting of
		706	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		707	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		708	entry in more detail.
		709
		710	C<$name> is the name of the entry.
		711
		712	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		713
		714	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		715	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		716	C<IO::AIO::DT_WHT>.
		717
		718	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		719	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		720	scalars are read-only: you can not modify them.
		721
		722	C<$inode> is the inode number (which might not be exact on systems with 64
		723	bit inode numbers and 32 bit perls). This field has unspecified content on
		724	systems that do not deliver the inode information.
		725
		726	=item IO::AIO::READDIR_DIRS_FIRST
		727
		728	When this flag is set, then the names will be returned in an order where
		729	likely directories come first, in optimal stat order. This is useful when
		730	you need to quickly find directories, or you want to find all directories
		731	while avoiding to stat() each entry.
		732
		733	If the system returns type information in readdir, then this is used
		734	to find directories directly. Otherwise, likely directories are names
		735	beginning with ".", or otherwise names with no dots, of which names with
		736	short names are tried first.
		737
		738	=item IO::AIO::READDIR_STAT_ORDER
		739
		740	When this flag is set, then the names will be returned in an order
		741	suitable for stat()'ing each one. That is, when you plan to stat()
		742	all files in the given directory, then the returned order will likely
		743	be fastest.
		744
		745	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		746	the likely dirs come first, resulting in a less optimal stat order.
		747
		748	=item IO::AIO::READDIR_FOUND_UNKNOWN
		749
		750	This flag should not be set when calling C<aio_readdirx>. Instead, it
		751	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		752	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
		753	C<$type>'s are known, which can be used to speed up some algorithms.
		754
		755	=back
		756
456		757
457	=item aio_load $path, $data, $callback->($status)	758	=item aio_load $path, $data, $callback->($status)
458		759
459	This is a composite request that tries to fully load the given file into	760	This is a composite request that tries to fully load the given file into
460	memory. Status is the same as with aio_read.	761	memory. Status is the same as with aio_read.
461		762
462	=cut	763	=cut
463		764
464	sub aio_load($$;$) {	765	sub aio_load($$;$) {
465	aio_block {
466	my ($path, undef, $cb) = @_;	766	my ($path, undef, $cb) = @_;
467	my $data = \$_[1];	767	my $data = \$_[1];
468		768
469	my $pri = aioreq_pri;	769	my $pri = aioreq_pri;
470	my $grp = aio_group $cb;	770	my $grp = aio_group $cb;
		771
		772	aioreq_pri $pri;
		773	add $grp aio_open $path, O_RDONLY, 0, sub {
		774	my $fh = shift
		775	or return $grp->result (-1);
471		776
472	aioreq_pri $pri;	777	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), $$data, 0, sub {	778	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
479	$grp->result ($_[0]);	779	$grp->result ($_[0]);
480	};
481	};	780	};
482
483	$grp
484	}	781	};
		782
		783	$grp
485	}	784	}
486		785
487	=item aio_copy $srcpath, $dstpath, $callback->($status)	786	=item aio_copy $srcpath, $dstpath, $callback->($status)
488		787
489	Try to copy the I<file> (directories not supported as either source or	788	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	789	destination) from C<$srcpath> to C<$dstpath> and call the callback with
491	the C<0> (error) or C<-1> ok.	790	a status of C<0> (ok) or C<-1> (error, see C<$!>).
492		791
493	This is a composite request that it creates the destination file with	792	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	793	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	794	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
496	uid/gid, in that order.	795	uid/gid, in that order.
497		796
498	If an error occurs, the partial destination file will be unlinked, if	797	If an error occurs, the partial destination file will be unlinked, if
…		…
500	errors are being ignored.	799	errors are being ignored.
501		800
502	=cut	801	=cut
503		802
504	sub aio_copy($$;$) {	803	sub aio_copy($$;$) {
505	aio_block {
506	my ($src, $dst, $cb) = @_;	804	my ($src, $dst, $cb) = @_;
507		805
508	my $pri = aioreq_pri;	806	my $pri = aioreq_pri;
509	my $grp = aio_group $cb;	807	my $grp = aio_group $cb;
510		808
511	aioreq_pri $pri;	809	aioreq_pri $pri;
512	add $grp aio_open $src, O_RDONLY, 0, sub {	810	add $grp aio_open $src, O_RDONLY, 0, sub {
513	if (my $src_fh = $_[0]) {	811	if (my $src_fh = $_[0]) {
514	my @stat = stat $src_fh;	812	my @stat = stat $src_fh; # hmm, might block over nfs?
515		813
516	aioreq_pri $pri;	814	aioreq_pri $pri;
517	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	815	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
518	if (my $dst_fh = $_[0]) {	816	if (my $dst_fh = $_[0]) {
519	aioreq_pri $pri;	817	aioreq_pri $pri;
520	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	818	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
521	if ($_[0] == $stat[7]) {	819	if ($_[0] == $stat[7]) {
522	$grp->result (0);	820	$grp->result (0);
523	close $src_fh;	821	close $src_fh;
524		822
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 {	823	my $ch = sub {
531	$grp->result (-1);
532	close $src_fh;
533	close $dst_fh;
534
535	aioreq $pri;	824	aioreq_pri $pri;
		825	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		826	aioreq_pri $pri;
		827	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		828	aioreq_pri $pri;
536	add $grp aio_unlink $dst;	829	add $grp aio_close $dst_fh;
		830	}
		831	};
537	}	832	};
		833
		834	aioreq_pri $pri;
		835	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		836	if ($_[0] < 0 && $! == ENOSYS) {
		837	aioreq_pri $pri;
		838	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		839	} else {
		840	$ch->();
		841	}
		842	};
		843	} else {
		844	$grp->result (-1);
		845	close $src_fh;
		846	close $dst_fh;
		847
		848	aioreq $pri;
		849	add $grp aio_unlink $dst;
538	};	850	}
539	} else {
540	$grp->result (-1);
541	}	851	};
		852	} else {
		853	$grp->result (-1);
542	},	854	}
543
544	} else {
545	$grp->result (-1);
546	}	855	},
		856
		857	} else {
		858	$grp->result (-1);
547	};	859	}
548
549	$grp
550	}	860	};
		861
		862	$grp
551	}	863	}
552		864
553	=item aio_move $srcpath, $dstpath, $callback->($status)	865	=item aio_move $srcpath, $dstpath, $callback->($status)
554		866
555	Try to move the I<file> (directories not supported as either source or	867	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	868	destination) from C<$srcpath> to C<$dstpath> and call the callback with
557	the C<0> (error) or C<-1> ok.	869	a status of C<0> (ok) or C<-1> (error, see C<$!>).
558		870
559	This is a composite request that tries to rename(2) the file first. If	871	This is a composite request that tries to rename(2) the file first; if
560	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if	872	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
561	that is successful, unlinking the C<$srcpath>.	873	that is successful, unlinks the C<$srcpath>.
562		874
563	=cut	875	=cut
564		876
565	sub aio_move($$;$) {	877	sub aio_move($$;$) {
566	aio_block {
567	my ($src, $dst, $cb) = @_;	878	my ($src, $dst, $cb) = @_;
568		879
569	my $pri = aioreq_pri;	880	my $pri = aioreq_pri;
570	my $grp = aio_group $cb;	881	my $grp = aio_group $cb;
571		882
572	aioreq_pri $pri;	883	aioreq_pri $pri;
573	add $grp aio_rename $src, $dst, sub {	884	add $grp aio_rename $src, $dst, sub {
574	if ($_[0] && $! == EXDEV) {	885	if ($_[0] && $! == EXDEV) {
575	aioreq_pri $pri;	886	aioreq_pri $pri;
576	add $grp aio_copy $src, $dst, sub {	887	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]);	888	$grp->result ($_[0]);
		889
		890	unless ($_[0]) {
		891	aioreq_pri $pri;
		892	add $grp aio_unlink $src;
		893	}
586	}	894	};
		895	} else {
		896	$grp->result ($_[0]);
587	};	897	}
588
589	$grp
590	}	898	};
		899
		900	$grp
591	}	901	}
592		902
593	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	903	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
594		904
595	Scans a directory (similar to C<aio_readdir>) but additionally tries to	905	Scans a directory (similar to C<aio_readdir>) but additionally tries to
…		…
615		925
616	Implementation notes.	926	Implementation notes.
617		927
618	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	928	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
619		929
		930	If readdir returns file type information, then this is used directly to
		931	find directories.
		932
620	After reading the directory, the modification time, size etc. of the	933	Otherwise, after reading the directory, the modification time, size etc.
621	directory before and after the readdir is checked, and if they match (and	934	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	935	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	936	how many entries are directories (if >= 2). Otherwise, no knowledge of the
624	of subdirectories will be assumed.	937	number of subdirectories will be assumed.
625		938
626	Then entries will be sorted into likely directories (everything without	939	Then entries will be sorted into likely directories a non-initial dot
627	a non-initial dot currently) and likely non-directories (everything	940	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,	941	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	942	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	943	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	944	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	945	filesystems might detect the type of the entry without reading the inode
633	data (e.g. ext2fs filetype feature).	946	data (e.g. ext2fs filetype feature), even on systems that cannot return
		947	the filetype information on readdir.
634		948
635	If the known number of directories (link count - 2) has been reached, the	949	If the known number of directories (link count - 2) has been reached, the
636	rest of the entries is assumed to be non-directories.	950	rest of the entries is assumed to be non-directories.
637		951
638	This only works with certainty on POSIX (= UNIX) filesystems, which	952	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
643	directory counting heuristic.	957	directory counting heuristic.
644		958
645	=cut	959	=cut
646		960
647	sub aio_scandir($$;$) {	961	sub aio_scandir($$;$) {
648	aio_block {
649	my ($path, $maxreq, $cb) = @_;	962	my ($path, $maxreq, $cb) = @_;
650		963
651	my $pri = aioreq_pri;	964	my $pri = aioreq_pri;
652		965
653	my $grp = aio_group $cb;	966	my $grp = aio_group $cb;
654		967
655	$maxreq = 4 if $maxreq <= 0;	968	$maxreq = 4 if $maxreq <= 0;
656		969
657	# stat once	970	# stat once
		971	aioreq_pri $pri;
		972	add $grp aio_stat $path, sub {
		973	return $grp->result () if $_[0];
		974	my $now = time;
		975	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		976
		977	# read the directory entries
658	aioreq_pri $pri;	978	aioreq_pri $pri;
659	add $grp aio_stat $path, sub {	979	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
		980	my $entries = shift
660	return $grp->result () if $_[0];	981	or return $grp->result ();
661	my $now = time;
662	my $hash1 = join ":", (stat _)[0,1,3,7,9];
663		982
664	# read the directory entries	983	# stat the dir another time
665	aioreq_pri $pri;	984	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 {	985	add $grp aio_stat $path, sub {
673	my $hash2 = join ":", (stat _)[0,1,3,7,9];	986	my $hash2 = join ":", (stat _)[0,1,3,7,9];
674		987
675	my $ndirs;	988	my $ndirs;
676		989
677	# take the slow route if anything looks fishy	990	# take the slow route if anything looks fishy
678	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	991	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
679	$ndirs = -1;	992	$ndirs = -1;
680	} else {	993	} else {
681	# if nlink == 2, we are finished	994	# if nlink == 2, we are finished
682	# on non-posix-fs's, we rely on nlink < 2	995	# for non-posix-fs's, we rely on nlink < 2
683	$ndirs = (stat _)[3] - 2	996	$ndirs = (stat _)[3] - 2
684	or return $grp->result ([], $entries);	997	or return $grp->result ([], $entries);
685	}	998	}
686		999
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);	1000	my (@dirs, @nondirs);
695		1001
696	my $statgrp = add $grp aio_group sub {	1002	my $statgrp = add $grp aio_group sub {
697	$grp->result (\@dirs, \@nondirs);	1003	$grp->result (\@dirs, \@nondirs);
698	};	1004	};
699		1005
700	limit $statgrp $maxreq;	1006	limit $statgrp $maxreq;
701	feed $statgrp sub {	1007	feed $statgrp sub {
702	return unless @$entries;	1008	return unless @$entries;
703	my $entry = pop @$entries;	1009	my $entry = shift @$entries;
704		1010
705	aioreq_pri $pri;	1011	aioreq_pri $pri;
706	add $statgrp aio_stat "$path/$entry/.", sub {	1012	add $statgrp aio_stat "$path/$entry/.", sub {
707	if ($_[0] < 0) {	1013	if ($_[0] < 0) {
708	push @nondirs, $entry;	1014	push @nondirs, $entry;
709	} else {	1015	} else {
710	# need to check for real directory	1016	# need to check for real directory
711	aioreq_pri $pri;	1017	aioreq_pri $pri;
712	add $statgrp aio_lstat "$path/$entry", sub {	1018	add $statgrp aio_lstat "$path/$entry", sub {
713	if (-d _) {	1019	if (-d _) {
714	push @dirs, $entry;	1020	push @dirs, $entry;
715		1021
716	unless (--$ndirs) {	1022	unless (--$ndirs) {
717	push @nondirs, @$entries;	1023	push @nondirs, @$entries;
718	feed $statgrp;	1024	feed $statgrp;
719	}
720	} else {
721	push @nondirs, $entry;
722	}	1025	}
		1026	} else {
		1027	push @nondirs, $entry;
723	}	1028	}
724	}	1029	}
725	};	1030	}
726	};	1031	};
727	};	1032	};
728	};	1033	};
729	};	1034	};
730
731	$grp
732	}	1035	};
		1036
		1037	$grp
733	}	1038	}
734		1039
735	=item aio_rmtree $path, $callback->($status)	1040	=item aio_rmtree $path, $callback->($status)
736		1041
737	Delete a directory tree starting (and including) C<$path>, return the	1042	Delete a directory tree starting (and including) C<$path>, return the
…		…
741		1046
742	=cut	1047	=cut
743		1048
744	sub aio_rmtree;	1049	sub aio_rmtree;
745	sub aio_rmtree($;$) {	1050	sub aio_rmtree($;$) {
746	aio_block {
747	my ($path, $cb) = @_;	1051	my ($path, $cb) = @_;
748		1052
749	my $pri = aioreq_pri;	1053	my $pri = aioreq_pri;
750	my $grp = aio_group $cb;	1054	my $grp = aio_group $cb;
751		1055
752	aioreq_pri $pri;	1056	aioreq_pri $pri;
753	add $grp aio_scandir $path, 0, sub {	1057	add $grp aio_scandir $path, 0, sub {
754	my ($dirs, $nondirs) = @_;	1058	my ($dirs, $nondirs) = @_;
755		1059
756	my $dirgrp = aio_group sub {	1060	my $dirgrp = aio_group sub {
757	add $grp aio_rmdir $path, sub {	1061	add $grp aio_rmdir $path, sub {
758	$grp->result ($_[0]);	1062	$grp->result ($_[0]);
759	};
760	};	1063	};
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	};	1064	};
767		1065
768	$grp	1066	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1067	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1068
		1069	add $grp $dirgrp;
769	}	1070	};
		1071
		1072	$grp
770	}	1073	}
		1074
		1075	=item aio_sync $callback->($status)
		1076
		1077	Asynchronously call sync and call the callback when finished.
771		1078
772	=item aio_fsync $fh, $callback->($status)	1079	=item aio_fsync $fh, $callback->($status)
773		1080
774	Asynchronously call fsync on the given filehandle and call the callback	1081	Asynchronously call fsync on the given filehandle and call the callback
775	with the fsync result code.	1082	with the fsync result code.
…		…
779	Asynchronously call fdatasync on the given filehandle and call the	1086	Asynchronously call fdatasync on the given filehandle and call the
780	callback with the fdatasync result code.	1087	callback with the fdatasync result code.
781		1088
782	If this call isn't available because your OS lacks it or it couldn't be	1089	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.	1090	detected, it will be emulated by calling C<fsync> instead.
		1091
		1092	=item aio_syncfs $fh, $callback->($status)
		1093
		1094	Asynchronously call the syncfs syscall to sync the filesystem associated
		1095	to the given filehandle and call the callback with the syncfs result
		1096	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1097	errno to C<ENOSYS> nevertheless.
		1098
		1099	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1100
		1101	Sync the data portion of the file specified by C<$offset> and C<$length>
		1102	to disk (but NOT the metadata), by calling the Linux-specific
		1103	sync_file_range call. If sync_file_range is not available or it returns
		1104	ENOSYS, then fdatasync or fsync is being substituted.
		1105
		1106	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1107	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1108	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1109	manpage for details.
		1110
		1111	=item aio_pathsync $path, $callback->($status)
		1112
		1113	This request tries to open, fsync and close the given path. This is a
		1114	composite request intended to sync directories after directory operations
		1115	(E.g. rename). This might not work on all operating systems or have any
		1116	specific effect, but usually it makes sure that directory changes get
		1117	written to disc. It works for anything that can be opened for read-only,
		1118	not just directories.
		1119
		1120	Future versions of this function might fall back to other methods when
		1121	C<fsync> on the directory fails (such as calling C<sync>).
		1122
		1123	Passes C<0> when everything went ok, and C<-1> on error.
		1124
		1125	=cut
		1126
		1127	sub aio_pathsync($;$) {
		1128	my ($path, $cb) = @_;
		1129
		1130	my $pri = aioreq_pri;
		1131	my $grp = aio_group $cb;
		1132
		1133	aioreq_pri $pri;
		1134	add $grp aio_open $path, O_RDONLY, 0, sub {
		1135	my ($fh) = @_;
		1136	if ($fh) {
		1137	aioreq_pri $pri;
		1138	add $grp aio_fsync $fh, sub {
		1139	$grp->result ($_[0]);
		1140
		1141	aioreq_pri $pri;
		1142	add $grp aio_close $fh;
		1143	};
		1144	} else {
		1145	$grp->result (-1);
		1146	}
		1147	};
		1148
		1149	$grp
		1150	}
		1151
		1152	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1153
		1154	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1155	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1156	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1157	scalar must only be modified in-place while an aio operation is pending on
		1158	it).
		1159
		1160	It calls the C<msync> function of your OS, if available, with the memory
		1161	area starting at C<$offset> in the string and ending C<$length> bytes
		1162	later. If C<$length> is negative, counts from the end, and if C<$length>
		1163	is C<undef>, then it goes till the end of the string. The flags can be
		1164	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1165	C<IO::AIO::MS_SYNC>.
		1166
		1167	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1168
		1169	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1170	scalars.
		1171
		1172	It touches (reads or writes) all memory pages in the specified
		1173	range inside the scalar. All caveats and parameters are the same
		1174	as for C<aio_msync>, above, except for flags, which must be either
		1175	C<0> (which reads all pages and ensures they are instantiated) or
		1176	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1177	writing an octet from it, which dirties the page).
		1178
		1179	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1180
		1181	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1182	scalars.
		1183
		1184	It reads in all the pages of the underlying storage into memory (if any)
		1185	and locks them, so they are not getting swapped/paged out or removed.
		1186
		1187	If C<$length> is undefined, then the scalar will be locked till the end.
		1188
		1189	On systems that do not implement C<mlock>, this function returns C<-1>
		1190	and sets errno to C<ENOSYS>.
		1191
		1192	Note that the corresponding C<munlock> is synchronous and is
		1193	documented under L<MISCELLANEOUS FUNCTIONS>.
		1194
		1195	Example: open a file, mmap and mlock it - both will be undone when
		1196	C<$data> gets destroyed.
		1197
		1198	open my $fh, "<", $path or die "$path: $!";
		1199	my $data;
		1200	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1201	aio_mlock $data; # mlock in background
		1202
		1203	=item aio_mlockall $flags, $callback->($status)
		1204
		1205	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1206	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1207
		1208	On systems that do not implement C<mlockall>, this function returns C<-1>
		1209	and sets errno to C<ENOSYS>.
		1210
		1211	Note that the corresponding C<munlockall> is synchronous and is
		1212	documented under L<MISCELLANEOUS FUNCTIONS>.
		1213
		1214	Example: asynchronously lock all current and future pages into memory.
		1215
		1216	aio_mlockall IO::AIO::MCL_FUTURE;
784		1217
785	=item aio_group $callback->(...)	1218	=item aio_group $callback->(...)
786		1219
787	This is a very special aio request: Instead of doing something, it is a	1220	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	1221	container for other aio requests, which is useful if you want to bundle
…		…
838	=item cancel $req	1271	=item cancel $req
839		1272
840	Cancels the request, if possible. Has the effect of skipping execution	1273	Cancels the request, if possible. Has the effect of skipping execution
841	when entering the B<execute> state and skipping calling the callback when	1274	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	1275	entering the the B<result> state, but will leave the request otherwise
843	untouched. That means that requests that currently execute will not be	1276	untouched (with the exception of readdir). That means that requests that
844	stopped and resources held by the request will not be freed prematurely.	1277	currently execute will not be stopped and resources held by the request
		1278	will not be freed prematurely.
845		1279
846	=item cb $req $callback->(...)	1280	=item cb $req $callback->(...)
847		1281
848	Replace (or simply set) the callback registered to the request.	1282	Replace (or simply set) the callback registered to the request.
849		1283
…		…
900	Their lifetime, simplified, looks like this: when they are empty, they	1334	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	1335	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	1336	C<done> state, they will also finish. Otherwise they will continue to
903	exist.	1337	exist.
904		1338
905	That means after creating a group you have some time to add requests. And	1339	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	1340	(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	1341	the C<poll_cb>). And in the callbacks of those requests, you can add
908	itself finish.	1342	further requests to the group. And only when all those requests have
		1343	finished will the the group itself finish.
909		1344
910	=over 4	1345	=over 4
911		1346
912	=item add $grp ...	1347	=item add $grp ...
913		1348
…		…
922	=item $grp->cancel_subs	1357	=item $grp->cancel_subs
923		1358
924	Cancel all subrequests and clears any feeder, but not the group request	1359	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.	1360	itself. Useful when you queued a lot of events but got a result early.
926		1361
		1362	The group request will finish normally (you cannot add requests to the
		1363	group).
		1364
927	=item $grp->result (...)	1365	=item $grp->result (...)
928		1366
929	Set the result value(s) that will be passed to the group callback when all	1367	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	1368	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,	1369	of errno (just like calling C<errno> without an error number). By default,
932	no argument will be passed and errno is zero.	1370	no argument will be passed and errno is zero.
933		1371
934	=item $grp->errno ([$errno])	1372	=item $grp->errno ([$errno])
935		1373
…		…
946	=item feed $grp $callback->($grp)	1384	=item feed $grp $callback->($grp)
947		1385
948	Sets a feeder/generator on this group: every group can have an attached	1386	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,	1387	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,	1388	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	1389	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>	1390	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
953	requests, delaying any later requests for a long time.	1391	delaying any later requests for a long time.
954		1392
955	To avoid this, and allow incremental generation of requests, you can	1393	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	1394	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>,	1395	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	1396	below) requests active in the group itself and is expected to queue more
…		…
962	not impose any limits).	1400	not impose any limits).
963		1401
964	If the feed does not queue more requests when called, it will be	1402	If the feed does not queue more requests when called, it will be
965	automatically removed from the group.	1403	automatically removed from the group.
966		1404
967	If the feed limit is C<0>, it will be set to C<2> automatically.	1405	If the feed limit is C<0> when this method is called, it will be set to
		1406	C<2> automatically.
968		1407
969	Example:	1408	Example:
970		1409
971	# stat all files in @files, but only ever use four aio requests concurrently:	1410	# stat all files in @files, but only ever use four aio requests concurrently:
972		1411
…		…
984	Sets the feeder limit for the group: The feeder will be called whenever	1423	Sets the feeder limit for the group: The feeder will be called whenever
985	the group contains less than this many requests.	1424	the group contains less than this many requests.
986		1425
987	Setting the limit to C<0> will pause the feeding process.	1426	Setting the limit to C<0> will pause the feeding process.
988		1427
		1428	The default value for the limit is C<0>, but note that setting a feeder
		1429	automatically bumps it up to C<2>.
		1430
989	=back	1431	=back
990		1432
991	=head2 SUPPORT FUNCTIONS	1433	=head2 SUPPORT FUNCTIONS
992		1434
993	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1435	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
…		…
995	=over 4	1437	=over 4
996		1438
997	=item $fileno = IO::AIO::poll_fileno	1439	=item $fileno = IO::AIO::poll_fileno
998		1440
999	Return the I<request result pipe file descriptor>. This filehandle must be	1441	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	1442	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	1443	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1002	to call C<poll_cb> to check the results.	1444	you have to call C<poll_cb> to check the results.
1003		1445
1004	See C<poll_cb> for an example.	1446	See C<poll_cb> for an example.
1005		1447
1006	=item IO::AIO::poll_cb	1448	=item IO::AIO::poll_cb
1007		1449
1008	Process some outstanding events on the result pipe. You have to call this	1450	Process some outstanding events on the result pipe. You have to call
1009	regularly. Returns the number of events processed. Returns immediately	1451	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	1452	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>.	1453	reason. Returns immediately when no events are outstanding. The amount of
		1454	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1455	C<IO::AIO::max_poll_time>.
1012		1456
1013	If not all requests were processed for whatever reason, the filehandle	1457	If not all requests were processed for whatever reason, the filehandle
1014	will still be ready when C<poll_cb> returns.	1458	will still be ready when C<poll_cb> returns, so normally you don't have to
		1459	do anything special to have it called later.
		1460
		1461	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1462	ready, it can be beneficial to call this function from loops which submit
		1463	a lot of requests, to make sure the results get processed when they become
		1464	available and not just when the loop is finished and the event loop takes
		1465	over again. This function returns very fast when there are no outstanding
		1466	requests.
1015		1467
1016	Example: Install an Event watcher that automatically calls	1468	Example: Install an Event watcher that automatically calls
1017	IO::AIO::poll_cb with high priority:	1469	IO::AIO::poll_cb with high priority (more examples can be found in the
		1470	SYNOPSIS section, at the top of this document):
1018		1471
1019	Event->io (fd => IO::AIO::poll_fileno,	1472	Event->io (fd => IO::AIO::poll_fileno,
1020	poll => 'r', async => 1,	1473	poll => 'r', async => 1,
1021	cb => \&IO::AIO::poll_cb);	1474	cb => \&IO::AIO::poll_cb);
		1475
		1476	=item IO::AIO::poll_wait
		1477
		1478	If there are any outstanding requests and none of them in the result
		1479	phase, wait till the result filehandle becomes ready for reading (simply
		1480	does a C<select> on the filehandle. This is useful if you want to
		1481	synchronously wait for some requests to finish).
		1482
		1483	See C<nreqs> for an example.
		1484
		1485	=item IO::AIO::poll
		1486
		1487	Waits until some requests have been handled.
		1488
		1489	Returns the number of requests processed, but is otherwise strictly
		1490	equivalent to:
		1491
		1492	IO::AIO::poll_wait, IO::AIO::poll_cb
		1493
		1494	=item IO::AIO::flush
		1495
		1496	Wait till all outstanding AIO requests have been handled.
		1497
		1498	Strictly equivalent to:
		1499
		1500	IO::AIO::poll_wait, IO::AIO::poll_cb
		1501	while IO::AIO::nreqs;
1022		1502
1023	=item IO::AIO::max_poll_reqs $nreqs	1503	=item IO::AIO::max_poll_reqs $nreqs
1024		1504
1025	=item IO::AIO::max_poll_time $seconds	1505	=item IO::AIO::max_poll_time $seconds
1026		1506
…		…
1051	# use a low priority so other tasks have priority	1531	# use a low priority so other tasks have priority
1052	Event->io (fd => IO::AIO::poll_fileno,	1532	Event->io (fd => IO::AIO::poll_fileno,
1053	poll => 'r', nice => 1,	1533	poll => 'r', nice => 1,
1054	cb => &IO::AIO::poll_cb);	1534	cb => &IO::AIO::poll_cb);
1055		1535
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	1536	=back
1084		1537
1085	=head3 CONTROLLING THE NUMBER OF THREADS	1538	=head3 CONTROLLING THE NUMBER OF THREADS
		1539
		1540	=over
1086		1541
1087	=item IO::AIO::min_parallel $nthreads	1542	=item IO::AIO::min_parallel $nthreads
1088		1543
1089	Set the minimum number of AIO threads to C<$nthreads>. The current	1544	Set the minimum number of AIO threads to C<$nthreads>. The current
1090	default is C<8>, which means eight asynchronous operations can execute	1545	default is C<8>, which means eight asynchronous operations can execute
…		…
1118		1573
1119	Under normal circumstances you don't need to call this function.	1574	Under normal circumstances you don't need to call this function.
1120		1575
1121	=item IO::AIO::max_idle $nthreads	1576	=item IO::AIO::max_idle $nthreads
1122		1577
1123	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1578	Limit the number of threads (default: 4) that are allowed to idle
1124	threads that did not get a request to process within 10 seconds). That	1579	(i.e., threads that did not get a request to process within the idle
1125	means if a thread becomes idle while C<$nthreads> other threads are also	1580	timeout (default: 10 seconds). That means if a thread becomes idle while
1126	idle, it will free its resources and exit.	1581	C<$nthreads> other threads are also idle, it will free its resources and
		1582	exit.
1127		1583
1128	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1584	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1129	to allow for extremely high load situations, but want to free resources	1585	to allow for extremely high load situations, but want to free resources
1130	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1586	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1131		1587
1132	The default is probably ok in most situations, especially if thread	1588	The default is probably ok in most situations, especially if thread
1133	creation is fast. If thread creation is very slow on your system you might	1589	creation is fast. If thread creation is very slow on your system you might
1134	want to use larger values.	1590	want to use larger values.
1135		1591
		1592	=item IO::AIO::idle_timeout $seconds
		1593
		1594	Sets the minimum idle timeout (default 10) after which worker threads are
		1595	allowed to exit. SEe C<IO::AIO::max_idle>.
		1596
1136	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1597	=item IO::AIO::max_outstanding $maxreqs
		1598
		1599	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1600	you do queue up more than this number of requests, the next call to
		1601	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1602	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1603	longer exceeded.
		1604
		1605	In other words, this setting does not enforce a queue limit, but can be
		1606	used to make poll functions block if the limit is exceeded.
1137		1607
1138	This is a very bad function to use in interactive programs because it	1608	This is a very bad function to use in interactive programs because it
1139	blocks, and a bad way to reduce concurrency because it is inexact: Better	1609	blocks, and a bad way to reduce concurrency because it is inexact: Better
1140	use an C<aio_group> together with a feed callback.	1610	use an C<aio_group> together with a feed callback.
1141		1611
1142	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1612	It's main use is in scripts without an event loop - when you want to stat
1143	to queue up more than this number of requests, the next call to the	1613	a lot of files, you can write somehting like this:
1144	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1145	function will block until the limit is no longer exceeded.
1146		1614
1147	The default value is very large, so there is no practical limit on the	1615	IO::AIO::max_outstanding 32;
1148	number of outstanding requests.
1149		1616
1150	You can still queue as many requests as you want. Therefore,	1617	for my $path (...) {
1151	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	1618	aio_stat $path , ...;
1152	as a stop gap to shield against fatal memory overflow (with large values).	1619	IO::AIO::poll_cb;
		1620	}
		1621
		1622	IO::AIO::flush;
		1623
		1624	The call to C<poll_cb> inside the loop will normally return instantly, but
		1625	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1626	some requests have been handled. This keeps the loop from pushing a large
		1627	number of C<aio_stat> requests onto the queue.
		1628
		1629	The default value for C<max_outstanding> is very large, so there is no
		1630	practical limit on the number of outstanding requests.
1153		1631
1154	=back	1632	=back
1155		1633
1156	=head3 STATISTICAL INFORMATION	1634	=head3 STATISTICAL INFORMATION
1157		1635
…		…
1177	Returns the number of requests currently in the pending state (executed,	1655	Returns the number of requests currently in the pending state (executed,
1178	but not yet processed by poll_cb).	1656	but not yet processed by poll_cb).
1179		1657
1180	=back	1658	=back
1181		1659
		1660	=head3 MISCELLANEOUS FUNCTIONS
		1661
		1662	IO::AIO implements some functions that might be useful, but are not
		1663	asynchronous.
		1664
		1665	=over 4
		1666
		1667	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1668
		1669	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1670	but is blocking (this makes most sense if you know the input data is
		1671	likely cached already and the output filehandle is set to non-blocking
		1672	operations).
		1673
		1674	Returns the number of bytes copied, or C<-1> on error.
		1675
		1676	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1677
		1678	Simply calls the C<posix_fadvise> function (see its
		1679	manpage for details). The following advice constants are
		1680	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1681	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1682	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1683
		1684	On systems that do not implement C<posix_fadvise>, this function returns
		1685	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1686
		1687	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1688
		1689	Simply calls the C<posix_madvise> function (see its
		1690	manpage for details). The following advice constants are
		1691	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1692	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1693
		1694	On systems that do not implement C<posix_madvise>, this function returns
		1695	ENOSYS, otherwise the return value of C<posix_madvise>.
		1696
		1697	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1698
		1699	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1700	$scalar (see its manpage for details). The following protect
		1701	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1702	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1703
		1704	On systems that do not implement C<mprotect>, this function returns
		1705	ENOSYS, otherwise the return value of C<mprotect>.
		1706
		1707	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1708
		1709	Memory-maps a file (or anonymous memory range) and attaches it to the
		1710	given C<$scalar>, which will act like a string scalar.
		1711
		1712	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1713	change the string length, and most read-only operations such as copying it
		1714	or searching it with regexes and so on.
		1715
		1716	Anything else is unsafe and will, at best, result in memory leaks.
		1717
		1718	The memory map associated with the C<$scalar> is automatically removed
		1719	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1720	C<IO::AIO::munmap> functions are called.
		1721
		1722	This calls the C<mmap>(2) function internally. See your system's manual
		1723	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1724
		1725	The C<$length> must be larger than zero and smaller than the actual
		1726	filesize.
		1727
		1728	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1729	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1730
		1731	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1732	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1733	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1734	(which is set to C<MAP_ANON> if your system only provides this
		1735	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1736	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1737	C<IO::AIO::MAP_NONBLOCK>
		1738
		1739	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1740
		1741	C<$offset> is the offset from the start of the file - it generally must be
		1742	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1743
		1744	Example:
		1745
		1746	use Digest::MD5;
		1747	use IO::AIO;
		1748
		1749	open my $fh, "<verybigfile"
		1750	or die "$!";
		1751
		1752	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1753	or die "verybigfile: $!";
		1754
		1755	my $fast_md5 = md5 $data;
		1756
		1757	=item IO::AIO::munmap $scalar
		1758
		1759	Removes a previous mmap and undefines the C<$scalar>.
		1760
		1761	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1762
		1763	Calls the C<munlock> function, undoing the effects of a previous
		1764	C<aio_mlock> call (see its description for details).
		1765
		1766	=item IO::AIO::munlockall
		1767
		1768	Calls the C<munlockall> function.
		1769
		1770	On systems that do not implement C<munlockall>, this function returns
		1771	ENOSYS, otherwise the return value of C<munlockall>.
		1772
		1773	=back
		1774
1182	=cut	1775	=cut
1183		1776
1184	# support function to convert a fd into a perl filehandle
1185	sub _fd2fh {
1186	return undef if $_[0] < 0;
1187
1188	# try to generate nice filehandles
1189	my $sym = "IO::AIO::fd#$_[0]";
1190	local *$sym;
1191
1192	open *$sym, "+<&=$_[0]" # usually works under any unix
1193	or open *$sym, "<&=$_[0]" # cygwin needs this
1194	or open *$sym, ">&=$_[0]" # or this
1195	or return undef;
1196
1197	*$sym
1198	}
1199
1200	min_parallel 8;	1777	min_parallel 8;
1201		1778
1202	END { flush }	1779	END { flush }
1203		1780
1204	1;	1781	1;
1205		1782
		1783	=head1 EVENT LOOP INTEGRATION
		1784
		1785	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1786	automatically into many event loops:
		1787
		1788	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1789	use AnyEvent::AIO;
		1790
		1791	You can also integrate IO::AIO manually into many event loops, here are
		1792	some examples of how to do this:
		1793
		1794	# EV integration
		1795	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1796
		1797	# Event integration
		1798	Event->io (fd => IO::AIO::poll_fileno,
		1799	poll => 'r',
		1800	cb => \&IO::AIO::poll_cb);
		1801
		1802	# Glib/Gtk2 integration
		1803	add_watch Glib::IO IO::AIO::poll_fileno,
		1804	in => sub { IO::AIO::poll_cb; 1 };
		1805
		1806	# Tk integration
		1807	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1808	readable => \&IO::AIO::poll_cb);
		1809
		1810	# Danga::Socket integration
		1811	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1812	\&IO::AIO::poll_cb);
		1813
1206	=head2 FORK BEHAVIOUR	1814	=head2 FORK BEHAVIOUR
1207		1815
1208	This module should do "the right thing" when the process using it forks:	1816	Usage of pthreads in a program changes the semantics of fork
		1817	considerably. Specifically, only async-safe functions can be called after
		1818	fork. Perl doesn't know about this, so in general, you cannot call fork
		1819	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		1820	pthreads, so this applies, but many other extensions and (for inexplicable
		1821	reasons) perl itself often is linked against pthreads, so this limitation
		1822	applies to quite a lot of perls.
1209		1823
1210	Before the fork, IO::AIO enters a quiescent state where no requests	1824	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1211	can be added in other threads and no results will be processed. After	1825	only works in the process that loaded it. Forking is fully supported, but
1212	the fork the parent simply leaves the quiescent state and continues	1826	using IO::AIO in the child is not.
1213	request/result processing, while the child frees the request/result queue
1214	(so that the requests started before the fork will only be handled in the
1215	parent). Threads will be started on demand until the limit set in the
1216	parent process has been reached again.
1217		1827
1218	In short: the parent will, after a short pause, continue as if fork had	1828	You might get around by not I<using> IO::AIO before (or after)
1219	not been called, while the child will act as if IO::AIO has not been used	1829	forking. You could also try to call the L<IO::AIO::reinit> function in the
1220	yet.	1830	child:
		1831
		1832	=over 4
		1833
		1834	=item IO::AIO::reinit
		1835
		1836	Abandons all current requests and I/O threads and simply reinitialises all
		1837	data structures. This is not an operation supported by any standards, but
		1838	happens to work on GNU/Linux and some newer BSD systems.
		1839
		1840	The only reasonable use for this function is to call it after forking, if
		1841	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		1842	the process will result in undefined behaviour. Calling it at any time
		1843	will also result in any undefined (by POSIX) behaviour.
		1844
		1845	=back
1221		1846
1222	=head2 MEMORY USAGE	1847	=head2 MEMORY USAGE
1223		1848
1224	Per-request usage:	1849	Per-request usage:
1225		1850
…		…
1227	bytes of memory. In addition, stat requests need a stat buffer (possibly	1852	bytes of memory. In addition, stat requests need a stat buffer (possibly
1228	a few hundred bytes), readdir requires a result buffer and so on. Perl	1853	a few hundred bytes), readdir requires a result buffer and so on. Perl
1229	scalars and other data passed into aio requests will also be locked and	1854	scalars and other data passed into aio requests will also be locked and
1230	will consume memory till the request has entered the done state.	1855	will consume memory till the request has entered the done state.
1231		1856
1232	This is now awfully much, so queuing lots of requests is not usually a	1857	This is not awfully much, so queuing lots of requests is not usually a
1233	problem.	1858	problem.
1234		1859
1235	Per-thread usage:	1860	Per-thread usage:
1236		1861
1237	In the execution phase, some aio requests require more memory for	1862	In the execution phase, some aio requests require more memory for
…		…
1242		1867
1243	Known bugs will be fixed in the next release.	1868	Known bugs will be fixed in the next release.
1244		1869
1245	=head1 SEE ALSO	1870	=head1 SEE ALSO
1246		1871
1247	L<Coro::AIO>.	1872	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1873	more natural syntax.
1248		1874
1249	=head1 AUTHOR	1875	=head1 AUTHOR
1250		1876
1251	Marc Lehmann <schmorp@schmorp.de>	1877	Marc Lehmann <schmorp@schmorp.de>
1252	http://home.schmorp.de/	1878	http://home.schmorp.de/

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