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Revision 1.85 by root, Sat Oct 28 01:40:30 2006 UTC vs.
Revision 1.202 by root, Tue Jul 5 14:02:15 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) = @_;	10	my $fh = shift
		11	or die "/etc/passwd: $!";
11	...	12	...
12	};	13	};
13		14
14	aio_unlink "/tmp/file", sub { };	15	aio_unlink "/tmp/file", sub { };
15		16
…		…
25	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
26		27
27	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
28	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
29		30
30	# AnyEvent integration
31	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
32	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
33
34	# Event integration
35	Event->io (fd => IO::AIO::poll_fileno,
36	poll => 'r',
37	cb => \&IO::AIO::poll_cb);
38
39	# Glib/Gtk2 integration
40	add_watch Glib::IO IO::AIO::poll_fileno,
41	in => sub { IO::AIO::poll_cb; 1 };
42
43	# Tk integration
44	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
45	readable => \&IO::AIO::poll_cb);
46
47	# Danga::Socket integration
48	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
49	\&IO::AIO::poll_cb);
50
51	=head1 DESCRIPTION	31	=head1 DESCRIPTION
52		32
53	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
54	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>).
55		36
56	Asynchronous means that operations that can normally block your program	37	Asynchronous means that operations that can normally block your program
57	(e.g. reading from disk) will be done asynchronously: the operation	38	(e.g. reading from disk) will be done asynchronously: the operation
58	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
59	is extremely useful for programs that need to stay interactive even	40	is extremely useful for programs that need to stay interactive even
…		…
61	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
62	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
63	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
64	concurrently.	45	concurrently.
65		46
66	While this works on all types of file descriptors (for example sockets),	47	While most of this works on all types of file descriptors (for
67	using these functions on file descriptors that support nonblocking	48	example sockets), using these functions on file descriptors that
68	operation (again, sockets, pipes etc.) is very inefficient. Use an event	49	support nonblocking operation (again, sockets, pipes etc.) is
69	loop for that (such as the L<Event|Event> module): IO::AIO will naturally	50	very inefficient. Use an event loop for that (such as the L<EV>
70	fit into such an event loop itself.	51	module): IO::AIO will naturally fit into such an event loop itself.
71		52
72	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
73	requests and signal their completion. You don't need thread support	54	requests and signal their completion. You don't need thread support
74	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
75	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
…		…
77	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
78	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
79	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
80	using threads anyway.	61	using threads anyway.
81		62
82	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,
83	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
84	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
85	never call C<poll_cb> (or other C<aio_> functions) recursively.	66	call C<poll_cb> (or other C<aio_> functions) recursively.
		67
		68	=head2 EXAMPLE
		69
		70	This is a simple example that uses the EV module and loads
		71	F</etc/passwd> asynchronously:
		72
		73	use Fcntl;
		74	use EV;
		75	use IO::AIO;
		76
		77	# register the IO::AIO callback with EV
		78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		79
		80	# queue the request to open /etc/passwd
		81	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
		82	my $fh = shift
		83	or die "error while opening: $!";
		84
		85	# stat'ing filehandles is generally non-blocking
		86	my $size = -s $fh;
		87
		88	# queue a request to read the file
		89	my $contents;
		90	aio_read $fh, 0, $size, $contents, 0, sub {
		91	$_[0] == $size
		92	or die "short read: $!";
		93
		94	close $fh;
		95
		96	# file contents now in $contents
		97	print $contents;
		98
		99	# exit event loop and program
		100	EV::unloop;
		101	};
		102	};
		103
		104	# possibly queue up other requests, or open GUI windows,
		105	# check for sockets etc. etc.
		106
		107	# process events as long as there are some:
		108	EV::loop;
86		109
87	=head1 REQUEST ANATOMY AND LIFETIME	110	=head1 REQUEST ANATOMY AND LIFETIME
88		111
89	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
90	directly visible to Perl.	113	directly visible to Perl.
…		…
132	Request has reached the end of its lifetime and holds no resources anymore	155	Request has reached the end of its lifetime and holds no resources anymore
133	(except possibly for the Perl object, but its connection to the actual	156	(except possibly for the Perl object, but its connection to the actual
134	aio request is severed and calling its methods will either do nothing or	157	aio request is severed and calling its methods will either do nothing or
135	result in a runtime error).	158	result in a runtime error).
136		159
		160	=back
		161
137	=cut	162	=cut
138		163
139	package IO::AIO;	164	package IO::AIO;
140		165
141	no warnings;	166	use Carp ();
142	use strict 'vars';	167
		168	use common::sense;
143		169
144	use base 'Exporter';	170	use base 'Exporter';
145		171
146	BEGIN {	172	BEGIN {
147	our $VERSION = '2.0';	173	our $VERSION = '3.93';
148		174
149	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
150	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
151	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync aio_fsync
152	aio_copy aio_group aio_nop aio_mknod);	178	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
		179	aio_rename aio_link aio_move aio_copy aio_group
		180	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		181	aio_chmod aio_utime aio_truncate
		182	aio_msync aio_mtouch aio_mlock aio_mlockall
		183	aio_statvfs);
		184
153	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
154	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
155	min_parallel max_parallel nreqs nready npending);	187	min_parallel max_parallel max_idle idle_timeout
		188	nreqs nready npending nthreads
		189	max_poll_time max_poll_reqs
		190	sendfile fadvise madvise
		191	mmap munmap munlock munlockall);
		192
		193	push @AIO_REQ, qw(aio_busy); # not exported
156		194
157	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	195	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
158		196
159	require XSLoader;	197	require XSLoader;
160	XSLoader::load ("IO::AIO", $VERSION);	198	XSLoader::load ("IO::AIO", $VERSION);
161	}	199	}
162		200
163	=head1 FUNCTIONS	201	=head1 FUNCTIONS
164		202
		203	=head2 QUICK OVERVIEW
		204
		205	This section simply lists the prototypes of the most important functions
		206	for quick reference. See the following sections for function-by-function
		207	documentation.
		208
		209	aio_open $pathname, $flags, $mode, $callback->($fh)
		210	aio_close $fh, $callback->($status)
		211	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		212	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		213	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		214	aio_readahead $fh,$offset,$length, $callback->($retval)
		215	aio_stat $fh_or_path, $callback->($status)
		216	aio_lstat $fh, $callback->($status)
		217	aio_statvfs $fh_or_path, $callback->($statvfs)
		218	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		219	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		220	aio_truncate $fh_or_path, $offset, $callback->($status)
		221	aio_chmod $fh_or_path, $mode, $callback->($status)
		222	aio_unlink $pathname, $callback->($status)
		223	aio_mknod $path, $mode, $dev, $callback->($status)
		224	aio_link $srcpath, $dstpath, $callback->($status)
		225	aio_symlink $srcpath, $dstpath, $callback->($status)
		226	aio_readlink $path, $callback->($link)
		227	aio_realpath $path, $callback->($link)
		228	aio_rename $srcpath, $dstpath, $callback->($status)
		229	aio_mkdir $pathname, $mode, $callback->($status)
		230	aio_rmdir $pathname, $callback->($status)
		231	aio_readdir $pathname, $callback->($entries)
		232	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		233	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		234	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		235	aio_load $path, $data, $callback->($status)
		236	aio_copy $srcpath, $dstpath, $callback->($status)
		237	aio_move $srcpath, $dstpath, $callback->($status)
		238	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		239	aio_rmtree $path, $callback->($status)
		240	aio_sync $callback->($status)
		241	aio_fsync $fh, $callback->($status)
		242	aio_fdatasync $fh, $callback->($status)
		243	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		244	aio_pathsync $path, $callback->($status)
		245	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		246	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		247	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		248	aio_mlockall $flags, $callback->($status)
		249	aio_group $callback->(...)
		250	aio_nop $callback->()
		251
		252	$prev_pri = aioreq_pri [$pri]
		253	aioreq_nice $pri_adjust
		254
		255	IO::AIO::poll_wait
		256	IO::AIO::poll_cb
		257	IO::AIO::poll
		258	IO::AIO::flush
		259	IO::AIO::max_poll_reqs $nreqs
		260	IO::AIO::max_poll_time $seconds
		261	IO::AIO::min_parallel $nthreads
		262	IO::AIO::max_parallel $nthreads
		263	IO::AIO::max_idle $nthreads
		264	IO::AIO::idle_timeout $seconds
		265	IO::AIO::max_outstanding $maxreqs
		266	IO::AIO::nreqs
		267	IO::AIO::nready
		268	IO::AIO::npending
		269
		270	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		271	IO::AIO::fadvise $fh, $offset, $len, $advice
		272	IO::AIO::madvise $scalar, $offset, $length, $advice
		273	IO::AIO::mprotect $scalar, $offset, $length, $protect
		274	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		275	IO::AIO::munlockall
		276
165	=head2 AIO FUNCTIONS	277	=head2 AIO REQUEST FUNCTIONS
166		278
167	All the C<aio_*> calls are more or less thin wrappers around the syscall	279	All the C<aio_*> calls are more or less thin wrappers around the syscall
168	with the same name (sans C<aio_>). The arguments are similar or identical,	280	with the same name (sans C<aio_>). The arguments are similar or identical,
169	and they all accept an additional (and optional) C<$callback> argument	281	and they all accept an additional (and optional) C<$callback> argument
170	which must be a code reference. This code reference will get called with	282	which must be a code reference. This code reference will get called with
171	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	283	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
172	perl, which usually delivers "false") as it's sole argument when the given	284	perl, which usually delivers "false") as its sole argument after the given
173	syscall has been executed asynchronously.	285	syscall has been executed asynchronously.
174		286
175	All functions expecting a filehandle keep a copy of the filehandle	287	All functions expecting a filehandle keep a copy of the filehandle
176	internally until the request has finished.	288	internally until the request has finished.
177		289
178	All requests return objects of type L<IO::AIO::REQ> that allow further	290	All functions return request objects of type L<IO::AIO::REQ> that allow
179	manipulation of those requests while they are in-flight.	291	further manipulation of those requests while they are in-flight.
180		292
181	The pathnames you pass to these routines I<must> be absolute and	293	The pathnames you pass to these routines I<must> be absolute and
182	encoded in byte form. The reason for the former is that at the time the	294	encoded as octets. The reason for the former is that at the time the
183	request is being executed, the current working directory could have	295	request is being executed, the current working directory could have
184	changed. Alternatively, you can make sure that you never change the	296	changed. Alternatively, you can make sure that you never change the
185	current working directory.	297	current working directory anywhere in the program and then use relative
		298	paths.
186		299
187	To encode pathnames to byte form, either make sure you either: a)	300	To encode pathnames as octets, either make sure you either: a) always pass
188	always pass in filenames you got from outside (command line, readdir	301	in filenames you got from outside (command line, readdir etc.) without
189	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	302	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
190	your pathnames to the locale (or other) encoding in effect in the user	303	your pathnames to the locale (or other) encoding in effect in the user
191	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	304	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
192	use something else.	305	use something else to ensure your scalar has the correct contents.
		306
		307	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		308	handles correctly whether it is set or not.
193		309
194	=over 4	310	=over 4
195		311
196	=item $prev_pri = aioreq_pri [$pri]	312	=item $prev_pri = aioreq_pri [$pri]
197		313
…		…
217	aio_read $_[0], ..., sub {	333	aio_read $_[0], ..., sub {
218	...	334	...
219	};	335	};
220	};	336	};
221		337
		338
222	=item aioreq_nice $pri_adjust	339	=item aioreq_nice $pri_adjust
223		340
224	Similar to C<aioreq_pri>, but subtracts the given value from the current	341	Similar to C<aioreq_pri>, but subtracts the given value from the current
225	priority, so effects are cumulative.	342	priority, so the effect is cumulative.
		343
226		344
227	=item aio_open $pathname, $flags, $mode, $callback->($fh)	345	=item aio_open $pathname, $flags, $mode, $callback->($fh)
228		346
229	Asynchronously open or create a file and call the callback with a newly	347	Asynchronously open or create a file and call the callback with a newly
230	created filehandle for the file.	348	created filehandle for the file.
…		…
236	list. They are the same as used by C<sysopen>.	354	list. They are the same as used by C<sysopen>.
237		355
238	Likewise, C<$mode> specifies the mode of the newly created file, if it	356	Likewise, C<$mode> specifies the mode of the newly created file, if it
239	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	357	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
240	except that it is mandatory (i.e. use C<0> if you don't create new files,	358	except that it is mandatory (i.e. use C<0> if you don't create new files,
241	and C<0666> or C<0777> if you do).	359	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		360	by the umask in effect then the request is being executed, so better never
		361	change the umask.
242		362
243	Example:	363	Example:
244		364
245	aio_open "/etc/passwd", O_RDONLY, 0, sub {	365	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
246	if ($_[0]) {	366	if ($_[0]) {
247	print "open successful, fh is $_[0]\n";	367	print "open successful, fh is $_[0]\n";
248	...	368	...
249	} else {	369	} else {
250	die "open failed: $!\n";	370	die "open failed: $!\n";
251	}	371	}
252	};	372	};
253		373
		374	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		375	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		376	following POSIX and non-POSIX constants are available (missing ones on
		377	your system are, as usual, C<0>):
		378
		379	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		380	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		381	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		382
		383
254	=item aio_close $fh, $callback->($status)	384	=item aio_close $fh, $callback->($status)
255		385
256	Asynchronously close a file and call the callback with the result	386	Asynchronously close a file and call the callback with the result
257	code. I<WARNING:> although accepted, you should not pass in a perl	387	code.
258	filehandle here, as perl will likely close the file descriptor another
259	time when the filehandle is destroyed. Normally, you can safely call perls
260	C<close> or just let filehandles go out of scope.
261		388
262	This is supposed to be a bug in the API, so that might change. It's	389	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
263	therefore best to avoid this function.	390	closing the file descriptor associated with the filehandle itself.
		391
		392	Therefore, C<aio_close> will not close the filehandle - instead it will
		393	use dup2 to overwrite the file descriptor with the write-end of a pipe
		394	(the pipe fd will be created on demand and will be cached).
		395
		396	Or in other words: the file descriptor will be closed, but it will not be
		397	free for reuse until the perl filehandle is closed.
		398
		399	=cut
264		400
265	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	401	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
266		402
267	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	403	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
268		404
269	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	405	Reads or writes C<$length> bytes from or to the specified C<$fh> and
270	into the scalar given by C<data> and offset C<dataoffset> and calls the	406	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
271	callback without the actual number of bytes read (or -1 on error, just	407	and calls the callback without the actual number of bytes read (or -1 on
272	like the syscall).	408	error, just like the syscall).
		409
		410	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		411	offset plus the actual number of bytes read.
		412
		413	If C<$offset> is undefined, then the current file descriptor offset will
		414	be used (and updated), otherwise the file descriptor offset will not be
		415	changed by these calls.
		416
		417	If C<$length> is undefined in C<aio_write>, use the remaining length of
		418	C<$data>.
		419
		420	If C<$dataoffset> is less than zero, it will be counted from the end of
		421	C<$data>.
273		422
274	The C<$data> scalar I<MUST NOT> be modified in any way while the request	423	The C<$data> scalar I<MUST NOT> be modified in any way while the request
275	is outstanding. Modifying it can result in segfaults or WW3 (if the	424	is outstanding. Modifying it can result in segfaults or World War III (if
276	necessary/optional hardware is installed).	425	the necessary/optional hardware is installed).
277		426
278	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	427	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
279	offset C<0> within the scalar:	428	offset C<0> within the scalar:
280		429
281	aio_read $fh, 7, 15, $buffer, 0, sub {	430	aio_read $fh, 7, 15, $buffer, 0, sub {
282	$_[0] > 0 or die "read error: $!";	431	$_[0] > 0 or die "read error: $!";
283	print "read $_[0] bytes: <$buffer>\n";	432	print "read $_[0] bytes: <$buffer>\n";
284	};	433	};
285		434
		435
286	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	436	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
287		437
288	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	438	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
289	reading at byte offset C<$in_offset>, and starts writing at the current	439	reading at byte offset C<$in_offset>, and starts writing at the current
290	file offset of C<$out_fh>. Because of that, it is not safe to issue more	440	file offset of C<$out_fh>. Because of that, it is not safe to issue more
291	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	441	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
292	other.	442	other. The same C<$in_fh> works fine though, as this function does not
		443	move or use the file offset of C<$in_fh>.
293		444
		445	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		446	are written, and there is no way to find out how many more bytes have been
		447	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		448	number of bytes written to C<$out_fh>. Only if the result value equals
		449	C<$length> one can assume that C<$length> bytes have been read.
		450
		451	Unlike with other C<aio_> functions, it makes a lot of sense to use
		452	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		453	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		454	the socket I/O will be non-blocking. Note, however, that you can run
		455	into a trap where C<aio_sendfile> reads some data with readahead, then
		456	fails to write all data, and when the socket is ready the next time, the
		457	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		458	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		459	resource usage.
		460
294	This call tries to make use of a native C<sendfile> syscall to provide	461	This call tries to make use of a native C<sendfile>-like syscall to
295	zero-copy operation. For this to work, C<$out_fh> should refer to a	462	provide zero-copy operation. For this to work, C<$out_fh> should refer to
296	socket, and C<$in_fh> should refer to mmap'able file.	463	a socket, and C<$in_fh> should refer to an mmap'able file.
297		464
298	If the native sendfile call fails or is not implemented, it will be	465	If a native sendfile cannot be found or it fails with C<ENOSYS>,
299	emulated, so you can call C<aio_sendfile> on any type of filehandle	466	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		467	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
300	regardless of the limitations of the operating system.	468	type of filehandle regardless of the limitations of the operating system.
301		469
302	Please note, however, that C<aio_sendfile> can read more bytes from	470	As native sendfile syscalls (as practically any non-POSIX interface hacked
303	C<$in_fh> than are written, and there is no way to find out how many	471	together in a hurry to improve benchmark numbers) tend to be rather buggy
304	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	472	on many systems, this implementation tries to work around some known bugs
305	provides the number of bytes written to C<$out_fh>. Only if the result	473	in Linux and FreeBSD kernels (probably others, too), but that might fail,
306	value equals C<$length> one can assume that C<$length> bytes have been	474	so you really really should check the return value of C<aio_sendfile> -
307	read.	475	fewre bytes than expected might have been transferred.
		476
308		477
309	=item aio_readahead $fh,$offset,$length, $callback->($retval)	478	=item aio_readahead $fh,$offset,$length, $callback->($retval)
310		479
311	C<aio_readahead> populates the page cache with data from a file so that	480	C<aio_readahead> populates the page cache with data from a file so that
312	subsequent reads from that file will not block on disk I/O. The C<$offset>	481	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
318	file. The current file offset of the file is left unchanged.	487	file. The current file offset of the file is left unchanged.
319		488
320	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	489	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
321	emulated by simply reading the data, which would have a similar effect.	490	emulated by simply reading the data, which would have a similar effect.
322		491
		492
323	=item aio_stat $fh_or_path, $callback->($status)	493	=item aio_stat $fh_or_path, $callback->($status)
324		494
325	=item aio_lstat $fh, $callback->($status)	495	=item aio_lstat $fh, $callback->($status)
326		496
327	Works like perl's C<stat> or C<lstat> in void context. The callback will	497	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
332	for an explanation.	502	for an explanation.
333		503
334	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	504	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
335	error when stat'ing a large file, the results will be silently truncated	505	error when stat'ing a large file, the results will be silently truncated
336	unless perl itself is compiled with large file support.	506	unless perl itself is compiled with large file support.
		507
		508	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		509	following constants and functions (if not implemented, the constants will
		510	be C<0> and the functions will either C<croak> or fall back on traditional
		511	behaviour).
		512
		513	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		514	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		515	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
337		516
338	Example: Print the length of F</etc/passwd>:	517	Example: Print the length of F</etc/passwd>:
339		518
340	aio_stat "/etc/passwd", sub {	519	aio_stat "/etc/passwd", sub {
341	$_[0] and die "stat failed: $!";	520	$_[0] and die "stat failed: $!";
342	print "size is ", -s _, "\n";	521	print "size is ", -s _, "\n";
343	};	522	};
344		523
		524
		525	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		526
		527	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		528	whether a file handle or path was passed.
		529
		530	On success, the callback is passed a hash reference with the following
		531	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		532	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		533	is passed.
		534
		535	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		536	C<ST_NOSUID>.
		537
		538	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		539	their correct value when available, or to C<0> on systems that do
		540	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		541	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		542	C<ST_NODIRATIME> and C<ST_RELATIME>.
		543
		544	Example: stat C</wd> and dump out the data if successful.
		545
		546	aio_statvfs "/wd", sub {
		547	my $f = $_[0]
		548	or die "statvfs: $!";
		549
		550	use Data::Dumper;
		551	say Dumper $f;
		552	};
		553
		554	# result:
		555	{
		556	bsize => 1024,
		557	bfree => 4333064312,
		558	blocks => 10253828096,
		559	files => 2050765568,
		560	flag => 4096,
		561	favail => 2042092649,
		562	bavail => 4333064312,
		563	ffree => 2042092649,
		564	namemax => 255,
		565	frsize => 1024,
		566	fsid => 1810
		567	}
		568
		569
		570	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		571
		572	Works like perl's C<utime> function (including the special case of $atime
		573	and $mtime being undef). Fractional times are supported if the underlying
		574	syscalls support them.
		575
		576	When called with a pathname, uses utimes(2) if available, otherwise
		577	utime(2). If called on a file descriptor, uses futimes(2) if available,
		578	otherwise returns ENOSYS, so this is not portable.
		579
		580	Examples:
		581
		582	# set atime and mtime to current time (basically touch(1)):
		583	aio_utime "path", undef, undef;
		584	# set atime to current time and mtime to beginning of the epoch:
		585	aio_utime "path", time, undef; # undef==0
		586
		587
		588	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		589
		590	Works like perl's C<chown> function, except that C<undef> for either $uid
		591	or $gid is being interpreted as "do not change" (but -1 can also be used).
		592
		593	Examples:
		594
		595	# same as "chown root path" in the shell:
		596	aio_chown "path", 0, -1;
		597	# same as above:
		598	aio_chown "path", 0, undef;
		599
		600
		601	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		602
		603	Works like truncate(2) or ftruncate(2).
		604
		605
		606	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		607
		608	Works like perl's C<chmod> function.
		609
		610
345	=item aio_unlink $pathname, $callback->($status)	611	=item aio_unlink $pathname, $callback->($status)
346		612
347	Asynchronously unlink (delete) a file and call the callback with the	613	Asynchronously unlink (delete) a file and call the callback with the
348	result code.	614	result code.
349		615
		616
350	=item aio_mknod $path, $mode, $dev, $callback->($status)	617	=item aio_mknod $path, $mode, $dev, $callback->($status)
351		618
		619	[EXPERIMENTAL]
		620
352	Asynchronously create a device node (or fifo). See mknod(2).	621	Asynchronously create a device node (or fifo). See mknod(2).
353		622
354	The only portable (POSIX) way of calling this function is:	623	The only (POSIX-) portable way of calling this function is:
355		624
356	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	625	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		626
		627	See C<aio_stat> for info about some potentially helpful extra constants
		628	and functions.
357		629
358	=item aio_link $srcpath, $dstpath, $callback->($status)	630	=item aio_link $srcpath, $dstpath, $callback->($status)
359		631
360	Asynchronously create a new link to the existing object at C<$srcpath> at	632	Asynchronously create a new link to the existing object at C<$srcpath> at
361	the path C<$dstpath> and call the callback with the result code.	633	the path C<$dstpath> and call the callback with the result code.
362		634
		635
363	=item aio_symlink $srcpath, $dstpath, $callback->($status)	636	=item aio_symlink $srcpath, $dstpath, $callback->($status)
364		637
365	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	638	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
366	the path C<$dstpath> and call the callback with the result code.	639	the path C<$dstpath> and call the callback with the result code.
367		640
		641
		642	=item aio_readlink $path, $callback->($link)
		643
		644	Asynchronously read the symlink specified by C<$path> and pass it to
		645	the callback. If an error occurs, nothing or undef gets passed to the
		646	callback.
		647
		648
		649	=item aio_realpath $path, $callback->($path)
		650
		651	Asynchronously make the path absolute and resolve any symlinks in
		652	C<$path>. The resulting path only consists of directories (Same as
		653	L<Cwd::realpath>).
		654
		655	This request can be used to get the absolute path of the current working
		656	directory by passing it a path of F<.> (a single dot).
		657
		658
368	=item aio_rename $srcpath, $dstpath, $callback->($status)	659	=item aio_rename $srcpath, $dstpath, $callback->($status)
369		660
370	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	661	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
371	rename(2) and call the callback with the result code.	662	rename(2) and call the callback with the result code.
372		663
		664
		665	=item aio_mkdir $pathname, $mode, $callback->($status)
		666
		667	Asynchronously mkdir (create) a directory and call the callback with
		668	the result code. C<$mode> will be modified by the umask at the time the
		669	request is executed, so do not change your umask.
		670
		671
373	=item aio_rmdir $pathname, $callback->($status)	672	=item aio_rmdir $pathname, $callback->($status)
374		673
375	Asynchronously rmdir (delete) a directory and call the callback with the	674	Asynchronously rmdir (delete) a directory and call the callback with the
376	result code.	675	result code.
		676
377		677
378	=item aio_readdir $pathname, $callback->($entries)	678	=item aio_readdir $pathname, $callback->($entries)
379		679
380	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	680	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
381	directory (i.e. opendir + readdir + closedir). The entries will not be	681	directory (i.e. opendir + readdir + closedir). The entries will not be
382	sorted, and will B<NOT> include the C<.> and C<..> entries.	682	sorted, and will B<NOT> include the C<.> and C<..> entries.
383		683
384	The callback a single argument which is either C<undef> or an array-ref	684	The callback is passed a single argument which is either C<undef> or an
385	with the filenames.	685	array-ref with the filenames.
		686
		687
		688	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		689
		690	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		691	behaviour and output format. In case of an error, C<$entries> will be
		692	C<undef>.
		693
		694	The flags are a combination of the following constants, ORed together (the
		695	flags will also be passed to the callback, possibly modified):
		696
		697	=over 4
		698
		699	=item IO::AIO::READDIR_DENTS
		700
		701	When this flag is off, then the callback gets an arrayref consisting of
		702	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		703	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		704	entry in more detail.
		705
		706	C<$name> is the name of the entry.
		707
		708	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		709
		710	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		711	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		712	C<IO::AIO::DT_WHT>.
		713
		714	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		715	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		716	scalars are read-only: you can not modify them.
		717
		718	C<$inode> is the inode number (which might not be exact on systems with 64
		719	bit inode numbers and 32 bit perls). This field has unspecified content on
		720	systems that do not deliver the inode information.
		721
		722	=item IO::AIO::READDIR_DIRS_FIRST
		723
		724	When this flag is set, then the names will be returned in an order where
		725	likely directories come first, in optimal stat order. This is useful when
		726	you need to quickly find directories, or you want to find all directories
		727	while avoiding to stat() each entry.
		728
		729	If the system returns type information in readdir, then this is used
		730	to find directories directly. Otherwise, likely directories are names
		731	beginning with ".", or otherwise names with no dots, of which names with
		732	short names are tried first.
		733
		734	=item IO::AIO::READDIR_STAT_ORDER
		735
		736	When this flag is set, then the names will be returned in an order
		737	suitable for stat()'ing each one. That is, when you plan to stat()
		738	all files in the given directory, then the returned order will likely
		739	be fastest.
		740
		741	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		742	the likely dirs come first, resulting in a less optimal stat order.
		743
		744	=item IO::AIO::READDIR_FOUND_UNKNOWN
		745
		746	This flag should not be set when calling C<aio_readdirx>. Instead, it
		747	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		748	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		749	C<$type>'s are known, which can be used to speed up some algorithms.
		750
		751	=back
		752
		753
		754	=item aio_load $path, $data, $callback->($status)
		755
		756	This is a composite request that tries to fully load the given file into
		757	memory. Status is the same as with aio_read.
		758
		759	=cut
		760
		761	sub aio_load($$;$) {
		762	my ($path, undef, $cb) = @_;
		763	my $data = \$_[1];
		764
		765	my $pri = aioreq_pri;
		766	my $grp = aio_group $cb;
		767
		768	aioreq_pri $pri;
		769	add $grp aio_open $path, O_RDONLY, 0, sub {
		770	my $fh = shift
		771	or return $grp->result (-1);
		772
		773	aioreq_pri $pri;
		774	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		775	$grp->result ($_[0]);
		776	};
		777	};
		778
		779	$grp
		780	}
386		781
387	=item aio_copy $srcpath, $dstpath, $callback->($status)	782	=item aio_copy $srcpath, $dstpath, $callback->($status)
388		783
389	Try to copy the I<file> (directories not supported as either source or	784	Try to copy the I<file> (directories not supported as either source or
390	destination) from C<$srcpath> to C<$dstpath> and call the callback with	785	destination) from C<$srcpath> to C<$dstpath> and call the callback with
391	the C<0> (error) or C<-1> ok.	786	a status of C<0> (ok) or C<-1> (error, see C<$!>).
392		787
393	This is a composite request that it creates the destination file with	788	This is a composite request that creates the destination file with
394	mode 0200 and copies the contents of the source file into it using	789	mode 0200 and copies the contents of the source file into it using
395	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	790	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
396	uid/gid, in that order.	791	uid/gid, in that order.
397		792
398	If an error occurs, the partial destination file will be unlinked, if	793	If an error occurs, the partial destination file will be unlinked, if
…		…
408	my $grp = aio_group $cb;	803	my $grp = aio_group $cb;
409		804
410	aioreq_pri $pri;	805	aioreq_pri $pri;
411	add $grp aio_open $src, O_RDONLY, 0, sub {	806	add $grp aio_open $src, O_RDONLY, 0, sub {
412	if (my $src_fh = $_[0]) {	807	if (my $src_fh = $_[0]) {
413	my @stat = stat $src_fh;	808	my @stat = stat $src_fh; # hmm, might block over nfs?
414		809
415	aioreq_pri $pri;	810	aioreq_pri $pri;
416	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	811	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
417	if (my $dst_fh = $_[0]) {	812	if (my $dst_fh = $_[0]) {
418	aioreq_pri $pri;	813	aioreq_pri $pri;
419	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	814	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
420	if ($_[0] == $stat[7]) {	815	if ($_[0] == $stat[7]) {
421	$grp->result (0);	816	$grp->result (0);
422	close $src_fh;	817	close $src_fh;
423		818
424	# those should not normally block. should. should.	819	my $ch = sub {
		820	aioreq_pri $pri;
		821	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		822	aioreq_pri $pri;
		823	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		824	aioreq_pri $pri;
		825	add $grp aio_close $dst_fh;
		826	}
		827	};
		828	};
		829
		830	aioreq_pri $pri;
		831	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		832	if ($_[0] < 0 && $! == ENOSYS) {
		833	aioreq_pri $pri;
425	utime $stat[8], $stat[9], $dst;	834	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
426	chmod $stat[2] & 07777, $dst_fh;	835	} else {
427	chown $stat[4], $stat[5], $dst_fh;	836	$ch->();
		837	}
428	close $dst_fh;	838	};
429	} else {	839	} else {
430	$grp->result (-1);	840	$grp->result (-1);
431	close $src_fh;	841	close $src_fh;
432	close $dst_fh;	842	close $dst_fh;
433		843
…		…
450		860
451	=item aio_move $srcpath, $dstpath, $callback->($status)	861	=item aio_move $srcpath, $dstpath, $callback->($status)
452		862
453	Try to move the I<file> (directories not supported as either source or	863	Try to move the I<file> (directories not supported as either source or
454	destination) from C<$srcpath> to C<$dstpath> and call the callback with	864	destination) from C<$srcpath> to C<$dstpath> and call the callback with
455	the C<0> (error) or C<-1> ok.	865	a status of C<0> (ok) or C<-1> (error, see C<$!>).
456		866
457	This is a composite request that tries to rename(2) the file first. If	867	This is a composite request that tries to rename(2) the file first; if
458	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if	868	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
459	that is successful, unlinking the C<$srcpath>.	869	that is successful, unlinks the C<$srcpath>.
460		870
461	=cut	871	=cut
462		872
463	sub aio_move($$;$) {	873	sub aio_move($$;$) {
464	my ($src, $dst, $cb) = @_;	874	my ($src, $dst, $cb) = @_;
…		…
471	if ($_[0] && $! == EXDEV) {	881	if ($_[0] && $! == EXDEV) {
472	aioreq_pri $pri;	882	aioreq_pri $pri;
473	add $grp aio_copy $src, $dst, sub {	883	add $grp aio_copy $src, $dst, sub {
474	$grp->result ($_[0]);	884	$grp->result ($_[0]);
475		885
476	if (!$_[0]) {	886	unless ($_[0]) {
477	aioreq_pri $pri;	887	aioreq_pri $pri;
478	add $grp aio_unlink $src;	888	add $grp aio_unlink $src;
479	}	889	}
480	};	890	};
481	} else {	891	} else {
…		…
511		921
512	Implementation notes.	922	Implementation notes.
513		923
514	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	924	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
515		925
		926	If readdir returns file type information, then this is used directly to
		927	find directories.
		928
516	After reading the directory, the modification time, size etc. of the	929	Otherwise, after reading the directory, the modification time, size etc.
517	directory before and after the readdir is checked, and if they match (and	930	of the directory before and after the readdir is checked, and if they
518	isn't the current time), the link count will be used to decide how many	931	match (and isn't the current time), the link count will be used to decide
519	entries are directories (if >= 2). Otherwise, no knowledge of the number	932	how many entries are directories (if >= 2). Otherwise, no knowledge of the
520	of subdirectories will be assumed.	933	number of subdirectories will be assumed.
521		934
522	Then entries will be sorted into likely directories (everything without	935	Then entries will be sorted into likely directories a non-initial dot
523	a non-initial dot currently) and likely non-directories (everything	936	currently) and likely non-directories (see C<aio_readdirx>). Then every
524	else). Then every entry plus an appended C</.> will be C<stat>'ed,	937	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
525	likely directories first. If that succeeds, it assumes that the entry	938	in order of their inode numbers. If that succeeds, it assumes that the
526	is a directory or a symlink to directory (which will be checked	939	entry is a directory or a symlink to directory (which will be checked
527	seperately). This is often faster than stat'ing the entry itself because	940	seperately). This is often faster than stat'ing the entry itself because
528	filesystems might detect the type of the entry without reading the inode	941	filesystems might detect the type of the entry without reading the inode
529	data (e.g. ext2fs filetype feature).	942	data (e.g. ext2fs filetype feature), even on systems that cannot return
		943	the filetype information on readdir.
530		944
531	If the known number of directories (link count - 2) has been reached, the	945	If the known number of directories (link count - 2) has been reached, the
532	rest of the entries is assumed to be non-directories.	946	rest of the entries is assumed to be non-directories.
533		947
534	This only works with certainty on POSIX (= UNIX) filesystems, which	948	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
538	as those tend to return 0 or 1 as link counts, which disables the	952	as those tend to return 0 or 1 as link counts, which disables the
539	directory counting heuristic.	953	directory counting heuristic.
540		954
541	=cut	955	=cut
542		956
543	sub aio_scandir($$$) {	957	sub aio_scandir($$;$) {
544	my ($path, $maxreq, $cb) = @_;	958	my ($path, $maxreq, $cb) = @_;
545		959
546	my $pri = aioreq_pri;	960	my $pri = aioreq_pri;
547		961
548	my $grp = aio_group $cb;	962	my $grp = aio_group $cb;
…		…
556	my $now = time;	970	my $now = time;
557	my $hash1 = join ":", (stat _)[0,1,3,7,9];	971	my $hash1 = join ":", (stat _)[0,1,3,7,9];
558		972
559	# read the directory entries	973	# read the directory entries
560	aioreq_pri $pri;	974	aioreq_pri $pri;
561	add $grp aio_readdir $path, sub {	975	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
562	my $entries = shift	976	my $entries = shift
563	or return $grp->result ();	977	or return $grp->result ();
564		978
565	# stat the dir another time	979	# stat the dir another time
566	aioreq_pri $pri;	980	aioreq_pri $pri;
…		…
572	# take the slow route if anything looks fishy	986	# take the slow route if anything looks fishy
573	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	987	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
574	$ndirs = -1;	988	$ndirs = -1;
575	} else {	989	} else {
576	# if nlink == 2, we are finished	990	# if nlink == 2, we are finished
577	# on non-posix-fs's, we rely on nlink < 2	991	# for non-posix-fs's, we rely on nlink < 2
578	$ndirs = (stat _)[3] - 2	992	$ndirs = (stat _)[3] - 2
579	or return $grp->result ([], $entries);	993	or return $grp->result ([], $entries);
580	}	994	}
581		995
582	# sort into likely dirs and likely nondirs
583	# dirs == files without ".", short entries first
584	$entries = [map $_->[0],
585	sort { $b->[1] cmp $a->[1] }
586	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
587	@$entries];
588
589	my (@dirs, @nondirs);	996	my (@dirs, @nondirs);
590		997
591	my $statgrp = add $grp aio_group sub {	998	my $statgrp = add $grp aio_group sub {
592	$grp->result (\@dirs, \@nondirs);	999	$grp->result (\@dirs, \@nondirs);
593	};	1000	};
594		1001
595	limit $statgrp $maxreq;	1002	limit $statgrp $maxreq;
596	feed $statgrp sub {	1003	feed $statgrp sub {
597	return unless @$entries;	1004	return unless @$entries;
598	my $entry = pop @$entries;	1005	my $entry = shift @$entries;
599		1006
600	aioreq_pri $pri;	1007	aioreq_pri $pri;
601	add $statgrp aio_stat "$path/$entry/.", sub {	1008	add $statgrp aio_stat "$path/$entry/.", sub {
602	if ($_[0] < 0) {	1009	if ($_[0] < 0) {
603	push @nondirs, $entry;	1010	push @nondirs, $entry;
…		…
624	};	1031	};
625		1032
626	$grp	1033	$grp
627	}	1034	}
628		1035
		1036	=item aio_rmtree $path, $callback->($status)
		1037
		1038	Delete a directory tree starting (and including) C<$path>, return the
		1039	status of the final C<rmdir> only. This is a composite request that
		1040	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		1041	everything else.
		1042
		1043	=cut
		1044
		1045	sub aio_rmtree;
		1046	sub aio_rmtree($;$) {
		1047	my ($path, $cb) = @_;
		1048
		1049	my $pri = aioreq_pri;
		1050	my $grp = aio_group $cb;
		1051
		1052	aioreq_pri $pri;
		1053	add $grp aio_scandir $path, 0, sub {
		1054	my ($dirs, $nondirs) = @_;
		1055
		1056	my $dirgrp = aio_group sub {
		1057	add $grp aio_rmdir $path, sub {
		1058	$grp->result ($_[0]);
		1059	};
		1060	};
		1061
		1062	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1063	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1064
		1065	add $grp $dirgrp;
		1066	};
		1067
		1068	$grp
		1069	}
		1070
		1071	=item aio_sync $callback->($status)
		1072
		1073	Asynchronously call sync and call the callback when finished.
		1074
629	=item aio_fsync $fh, $callback->($status)	1075	=item aio_fsync $fh, $callback->($status)
630		1076
631	Asynchronously call fsync on the given filehandle and call the callback	1077	Asynchronously call fsync on the given filehandle and call the callback
632	with the fsync result code.	1078	with the fsync result code.
633		1079
…		…
636	Asynchronously call fdatasync on the given filehandle and call the	1082	Asynchronously call fdatasync on the given filehandle and call the
637	callback with the fdatasync result code.	1083	callback with the fdatasync result code.
638		1084
639	If this call isn't available because your OS lacks it or it couldn't be	1085	If this call isn't available because your OS lacks it or it couldn't be
640	detected, it will be emulated by calling C<fsync> instead.	1086	detected, it will be emulated by calling C<fsync> instead.
		1087
		1088	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1089
		1090	Sync the data portion of the file specified by C<$offset> and C<$length>
		1091	to disk (but NOT the metadata), by calling the Linux-specific
		1092	sync_file_range call. If sync_file_range is not available or it returns
		1093	ENOSYS, then fdatasync or fsync is being substituted.
		1094
		1095	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1096	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1097	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1098	manpage for details.
		1099
		1100	=item aio_pathsync $path, $callback->($status)
		1101
		1102	This request tries to open, fsync and close the given path. This is a
		1103	composite request intended to sync directories after directory operations
		1104	(E.g. rename). This might not work on all operating systems or have any
		1105	specific effect, but usually it makes sure that directory changes get
		1106	written to disc. It works for anything that can be opened for read-only,
		1107	not just directories.
		1108
		1109	Future versions of this function might fall back to other methods when
		1110	C<fsync> on the directory fails (such as calling C<sync>).
		1111
		1112	Passes C<0> when everything went ok, and C<-1> on error.
		1113
		1114	=cut
		1115
		1116	sub aio_pathsync($;$) {
		1117	my ($path, $cb) = @_;
		1118
		1119	my $pri = aioreq_pri;
		1120	my $grp = aio_group $cb;
		1121
		1122	aioreq_pri $pri;
		1123	add $grp aio_open $path, O_RDONLY, 0, sub {
		1124	my ($fh) = @_;
		1125	if ($fh) {
		1126	aioreq_pri $pri;
		1127	add $grp aio_fsync $fh, sub {
		1128	$grp->result ($_[0]);
		1129
		1130	aioreq_pri $pri;
		1131	add $grp aio_close $fh;
		1132	};
		1133	} else {
		1134	$grp->result (-1);
		1135	}
		1136	};
		1137
		1138	$grp
		1139	}
		1140
		1141	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1142
		1143	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1144	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1145	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1146	scalar must only be modified in-place while an aio operation is pending on
		1147	it).
		1148
		1149	It calls the C<msync> function of your OS, if available, with the memory
		1150	area starting at C<$offset> in the string and ending C<$length> bytes
		1151	later. If C<$length> is negative, counts from the end, and if C<$length>
		1152	is C<undef>, then it goes till the end of the string. The flags can be
		1153	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1154	C<IO::AIO::MS_SYNC>.
		1155
		1156	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1157
		1158	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1159	scalars.
		1160
		1161	It touches (reads or writes) all memory pages in the specified
		1162	range inside the scalar. All caveats and parameters are the same
		1163	as for C<aio_msync>, above, except for flags, which must be either
		1164	C<0> (which reads all pages and ensures they are instantiated) or
		1165	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1166	writing an octet from it, which dirties the page).
		1167
		1168	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1169
		1170	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1171	scalars.
		1172
		1173	It reads in all the pages of the underlying storage into memory (if any)
		1174	and locks them, so they are not getting swapped/paged out or removed.
		1175
		1176	If C<$length> is undefined, then the scalar will be locked till the end.
		1177
		1178	On systems that do not implement C<mlock>, this function returns C<-1>
		1179	and sets errno to C<ENOSYS>.
		1180
		1181	Note that the corresponding C<munlock> is synchronous and is
		1182	documented under L<MISCELLANEOUS FUNCTIONS>.
		1183
		1184	Example: open a file, mmap and mlock it - both will be undone when
		1185	C<$data> gets destroyed.
		1186
		1187	open my $fh, "<", $path or die "$path: $!";
		1188	my $data;
		1189	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1190	aio_mlock $data; # mlock in background
		1191
		1192	=item aio_mlockall $flags, $callback->($status)
		1193
		1194	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1195	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1196
		1197	On systems that do not implement C<mlockall>, this function returns C<-1>
		1198	and sets errno to C<ENOSYS>.
		1199
		1200	Note that the corresponding C<munlockall> is synchronous and is
		1201	documented under L<MISCELLANEOUS FUNCTIONS>.
		1202
		1203	Example: asynchronously lock all current and future pages into memory.
		1204
		1205	aio_mlockall IO::AIO::MCL_FUTURE;
641		1206
642	=item aio_group $callback->(...)	1207	=item aio_group $callback->(...)
643		1208
644	This is a very special aio request: Instead of doing something, it is a	1209	This is a very special aio request: Instead of doing something, it is a
645	container for other aio requests, which is useful if you want to bundle	1210	container for other aio requests, which is useful if you want to bundle
…		…
695	=item cancel $req	1260	=item cancel $req
696		1261
697	Cancels the request, if possible. Has the effect of skipping execution	1262	Cancels the request, if possible. Has the effect of skipping execution
698	when entering the B<execute> state and skipping calling the callback when	1263	when entering the B<execute> state and skipping calling the callback when
699	entering the the B<result> state, but will leave the request otherwise	1264	entering the the B<result> state, but will leave the request otherwise
700	untouched. That means that requests that currently execute will not be	1265	untouched (with the exception of readdir). That means that requests that
701	stopped and resources held by the request will not be freed prematurely.	1266	currently execute will not be stopped and resources held by the request
		1267	will not be freed prematurely.
702		1268
703	=item cb $req $callback->(...)	1269	=item cb $req $callback->(...)
704		1270
705	Replace (or simply set) the callback registered to the request.	1271	Replace (or simply set) the callback registered to the request.
706		1272
…		…
757	Their lifetime, simplified, looks like this: when they are empty, they	1323	Their lifetime, simplified, looks like this: when they are empty, they
758	will finish very quickly. If they contain only requests that are in the	1324	will finish very quickly. If they contain only requests that are in the
759	C<done> state, they will also finish. Otherwise they will continue to	1325	C<done> state, they will also finish. Otherwise they will continue to
760	exist.	1326	exist.
761		1327
762	That means after creating a group you have some time to add requests. And	1328	That means after creating a group you have some time to add requests
763	in the callbacks of those requests, you can add further requests to the	1329	(precisely before the callback has been invoked, which is only done within
764	group. And only when all those requests have finished will the the group	1330	the C<poll_cb>). And in the callbacks of those requests, you can add
765	itself finish.	1331	further requests to the group. And only when all those requests have
		1332	finished will the the group itself finish.
766		1333
767	=over 4	1334	=over 4
768		1335
769	=item add $grp ...	1336	=item add $grp ...
770		1337
…		…
779	=item $grp->cancel_subs	1346	=item $grp->cancel_subs
780		1347
781	Cancel all subrequests and clears any feeder, but not the group request	1348	Cancel all subrequests and clears any feeder, but not the group request
782	itself. Useful when you queued a lot of events but got a result early.	1349	itself. Useful when you queued a lot of events but got a result early.
783		1350
		1351	The group request will finish normally (you cannot add requests to the
		1352	group).
		1353
784	=item $grp->result (...)	1354	=item $grp->result (...)
785		1355
786	Set the result value(s) that will be passed to the group callback when all	1356	Set the result value(s) that will be passed to the group callback when all
787	subrequests have finished and set thre groups errno to the current value	1357	subrequests have finished and set the groups errno to the current value
788	of errno (just like calling C<errno> without an error number). By default,	1358	of errno (just like calling C<errno> without an error number). By default,
789	no argument will be passed and errno is zero.	1359	no argument will be passed and errno is zero.
790		1360
791	=item $grp->errno ([$errno])	1361	=item $grp->errno ([$errno])
792		1362
…		…
803	=item feed $grp $callback->($grp)	1373	=item feed $grp $callback->($grp)
804		1374
805	Sets a feeder/generator on this group: every group can have an attached	1375	Sets a feeder/generator on this group: every group can have an attached
806	generator that generates requests if idle. The idea behind this is that,	1376	generator that generates requests if idle. The idea behind this is that,
807	although you could just queue as many requests as you want in a group,	1377	although you could just queue as many requests as you want in a group,
808	this might starve other requests for a potentially long time. For	1378	this might starve other requests for a potentially long time. For example,
809	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1379	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
810	requests, delaying any later requests for a long time.	1380	delaying any later requests for a long time.
811		1381
812	To avoid this, and allow incremental generation of requests, you can	1382	To avoid this, and allow incremental generation of requests, you can
813	instead a group and set a feeder on it that generates those requests. The	1383	instead a group and set a feeder on it that generates those requests. The
814	feed callback will be called whenever there are few enough (see C<limit>,	1384	feed callback will be called whenever there are few enough (see C<limit>,
815	below) requests active in the group itself and is expected to queue more	1385	below) requests active in the group itself and is expected to queue more
…		…
819	not impose any limits).	1389	not impose any limits).
820		1390
821	If the feed does not queue more requests when called, it will be	1391	If the feed does not queue more requests when called, it will be
822	automatically removed from the group.	1392	automatically removed from the group.
823		1393
824	If the feed limit is C<0>, it will be set to C<2> automatically.	1394	If the feed limit is C<0> when this method is called, it will be set to
		1395	C<2> automatically.
825		1396
826	Example:	1397	Example:
827		1398
828	# stat all files in @files, but only ever use four aio requests concurrently:	1399	# stat all files in @files, but only ever use four aio requests concurrently:
829		1400
…		…
841	Sets the feeder limit for the group: The feeder will be called whenever	1412	Sets the feeder limit for the group: The feeder will be called whenever
842	the group contains less than this many requests.	1413	the group contains less than this many requests.
843		1414
844	Setting the limit to C<0> will pause the feeding process.	1415	Setting the limit to C<0> will pause the feeding process.
845		1416
		1417	The default value for the limit is C<0>, but note that setting a feeder
		1418	automatically bumps it up to C<2>.
		1419
846	=back	1420	=back
847		1421
848	=head2 SUPPORT FUNCTIONS	1422	=head2 SUPPORT FUNCTIONS
849		1423
		1424	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1425
850	=over 4	1426	=over 4
851		1427
852	=item $fileno = IO::AIO::poll_fileno	1428	=item $fileno = IO::AIO::poll_fileno
853		1429
854	Return the I<request result pipe file descriptor>. This filehandle must be	1430	Return the I<request result pipe file descriptor>. This filehandle must be
855	polled for reading by some mechanism outside this module (e.g. Event or	1431	polled for reading by some mechanism outside this module (e.g. EV, Glib,
856	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1432	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
857	to call C<poll_cb> to check the results.	1433	you have to call C<poll_cb> to check the results.
858		1434
859	See C<poll_cb> for an example.	1435	See C<poll_cb> for an example.
860		1436
861	=item IO::AIO::poll_cb	1437	=item IO::AIO::poll_cb
862		1438
863	Process all outstanding events on the result pipe. You have to call this	1439	Process some outstanding events on the result pipe. You have to call
864	regularly. Returns the number of events processed. Returns immediately	1440	this regularly. Returns C<0> if all events could be processed (or there
865	when no events are outstanding.	1441	were no events to process), or C<-1> if it returned earlier for whatever
		1442	reason. Returns immediately when no events are outstanding. The amount of
		1443	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1444	C<IO::AIO::max_poll_time>.
866		1445
867	If not all requests were processed for whatever reason, the filehandle	1446	If not all requests were processed for whatever reason, the filehandle
868	will still be ready when C<poll_cb> returns.	1447	will still be ready when C<poll_cb> returns, so normally you don't have to
		1448	do anything special to have it called later.
		1449
		1450	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1451	ready, it can be beneficial to call this function from loops which submit
		1452	a lot of requests, to make sure the results get processed when they become
		1453	available and not just when the loop is finished and the event loop takes
		1454	over again. This function returns very fast when there are no outstanding
		1455	requests.
869		1456
870	Example: Install an Event watcher that automatically calls	1457	Example: Install an Event watcher that automatically calls
871	IO::AIO::poll_cb with high priority:	1458	IO::AIO::poll_cb with high priority (more examples can be found in the
		1459	SYNOPSIS section, at the top of this document):
872		1460
873	Event->io (fd => IO::AIO::poll_fileno,	1461	Event->io (fd => IO::AIO::poll_fileno,
874	poll => 'r', async => 1,	1462	poll => 'r', async => 1,
875	cb => \&IO::AIO::poll_cb);	1463	cb => \&IO::AIO::poll_cb);
876		1464
877	=item IO::AIO::poll_some $max_requests	1465	=item IO::AIO::poll_wait
878		1466
879	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests	1467	If there are any outstanding requests and none of them in the result
880	at a time.	1468	phase, wait till the result filehandle becomes ready for reading (simply
		1469	does a C<select> on the filehandle. This is useful if you want to
		1470	synchronously wait for some requests to finish).
881		1471
882	Useful if you want to ensure some level of interactiveness when perl is	1472	See C<nreqs> for an example.
883	not fast enough to process all requests in time.	1473
		1474	=item IO::AIO::poll
		1475
		1476	Waits until some requests have been handled.
		1477
		1478	Returns the number of requests processed, but is otherwise strictly
		1479	equivalent to:
		1480
		1481	IO::AIO::poll_wait, IO::AIO::poll_cb
		1482
		1483	=item IO::AIO::flush
		1484
		1485	Wait till all outstanding AIO requests have been handled.
		1486
		1487	Strictly equivalent to:
		1488
		1489	IO::AIO::poll_wait, IO::AIO::poll_cb
		1490	while IO::AIO::nreqs;
		1491
		1492	=item IO::AIO::max_poll_reqs $nreqs
		1493
		1494	=item IO::AIO::max_poll_time $seconds
		1495
		1496	These set the maximum number of requests (default C<0>, meaning infinity)
		1497	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1498	the maximum amount of time (default C<0>, meaning infinity) spent in
		1499	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1500	of time C<poll_cb> is allowed to use).
		1501
		1502	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1503	syscall per request processed, which is not normally a problem unless your
		1504	callbacks are really really fast or your OS is really really slow (I am
		1505	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1506
		1507	Setting these is useful if you want to ensure some level of
		1508	interactiveness when perl is not fast enough to process all requests in
		1509	time.
		1510
		1511	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
884		1512
885	Example: Install an Event watcher that automatically calls	1513	Example: Install an Event watcher that automatically calls
886	IO::AIO::poll_some with low priority, to ensure that other parts of the	1514	IO::AIO::poll_cb with low priority, to ensure that other parts of the
887	program get the CPU sometimes even under high AIO load.	1515	program get the CPU sometimes even under high AIO load.
888		1516
		1517	# try not to spend much more than 0.1s in poll_cb
		1518	IO::AIO::max_poll_time 0.1;
		1519
		1520	# use a low priority so other tasks have priority
889	Event->io (fd => IO::AIO::poll_fileno,	1521	Event->io (fd => IO::AIO::poll_fileno,
890	poll => 'r', nice => 1,	1522	poll => 'r', nice => 1,
891	cb => sub { IO::AIO::poll_some 256 });	1523	cb => &IO::AIO::poll_cb);
892		1524
893	=item IO::AIO::poll_wait	1525	=back
894		1526
895	Wait till the result filehandle becomes ready for reading (simply does a	1527	=head3 CONTROLLING THE NUMBER OF THREADS
896	C<select> on the filehandle. This is useful if you want to synchronously wait
897	for some requests to finish).
898		1528
899	See C<nreqs> for an example.	1529	=over
900
901	=item IO::AIO::nreqs
902
903	Returns the number of requests currently in the ready, execute or pending
904	states (i.e. for which their callback has not been invoked yet).
905
906	Example: wait till there are no outstanding requests anymore:
907
908	IO::AIO::poll_wait, IO::AIO::poll_cb
909	while IO::AIO::nreqs;
910
911	=item IO::AIO::nready
912
913	Returns the number of requests currently in the ready state (not yet
914	executed).
915
916	=item IO::AIO::npending
917
918	Returns the number of requests currently in the pending state (executed,
919	but not yet processed by poll_cb).
920
921	=item IO::AIO::flush
922
923	Wait till all outstanding AIO requests have been handled.
924
925	Strictly equivalent to:
926
927	IO::AIO::poll_wait, IO::AIO::poll_cb
928	while IO::AIO::nreqs;
929
930	=item IO::AIO::poll
931
932	Waits until some requests have been handled.
933
934	Strictly equivalent to:
935
936	IO::AIO::poll_wait, IO::AIO::poll_cb
937	if IO::AIO::nreqs;
938		1530
939	=item IO::AIO::min_parallel $nthreads	1531	=item IO::AIO::min_parallel $nthreads
940		1532
941	Set the minimum number of AIO threads to C<$nthreads>. The current	1533	Set the minimum number of AIO threads to C<$nthreads>. The current
942	default is C<8>, which means eight asynchronous operations can execute	1534	default is C<8>, which means eight asynchronous operations can execute
943	concurrently at any one time (the number of outstanding requests,	1535	concurrently at any one time (the number of outstanding requests,
944	however, is unlimited).	1536	however, is unlimited).
945		1537
946	IO::AIO starts threads only on demand, when an AIO request is queued and	1538	IO::AIO starts threads only on demand, when an AIO request is queued and
947	no free thread exists.	1539	no free thread exists. Please note that queueing up a hundred requests can
		1540	create demand for a hundred threads, even if it turns out that everything
		1541	is in the cache and could have been processed faster by a single thread.
948		1542
949	It is recommended to keep the number of threads relatively low, as some	1543	It is recommended to keep the number of threads relatively low, as some
950	Linux kernel versions will scale negatively with the number of threads	1544	Linux kernel versions will scale negatively with the number of threads
951	(higher parallelity => MUCH higher latency). With current Linux 2.6	1545	(higher parallelity => MUCH higher latency). With current Linux 2.6
952	versions, 4-32 threads should be fine.	1546	versions, 4-32 threads should be fine.
…		…
966	This module automatically runs C<max_parallel 0> at program end, to ensure	1560	This module automatically runs C<max_parallel 0> at program end, to ensure
967	that all threads are killed and that there are no outstanding requests.	1561	that all threads are killed and that there are no outstanding requests.
968		1562
969	Under normal circumstances you don't need to call this function.	1563	Under normal circumstances you don't need to call this function.
970		1564
		1565	=item IO::AIO::max_idle $nthreads
		1566
		1567	Limit the number of threads (default: 4) that are allowed to idle
		1568	(i.e., threads that did not get a request to process within the idle
		1569	timeout (default: 10 seconds). That means if a thread becomes idle while
		1570	C<$nthreads> other threads are also idle, it will free its resources and
		1571	exit.
		1572
		1573	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1574	to allow for extremely high load situations, but want to free resources
		1575	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1576
		1577	The default is probably ok in most situations, especially if thread
		1578	creation is fast. If thread creation is very slow on your system you might
		1579	want to use larger values.
		1580
		1581	=item IO::AIO::idle_timeout $seconds
		1582
		1583	Sets the minimum idle timeout (default 10) after which worker threads are
		1584	allowed to exit. SEe C<IO::AIO::max_idle>.
		1585
971	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1586	=item IO::AIO::max_outstanding $maxreqs
		1587
		1588	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1589	you do queue up more than this number of requests, the next call to
		1590	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1591	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1592	longer exceeded.
		1593
		1594	In other words, this setting does not enforce a queue limit, but can be
		1595	used to make poll functions block if the limit is exceeded.
972		1596
973	This is a very bad function to use in interactive programs because it	1597	This is a very bad function to use in interactive programs because it
974	blocks, and a bad way to reduce concurrency because it is inexact: Better	1598	blocks, and a bad way to reduce concurrency because it is inexact: Better
975	use an C<aio_group> together with a feed callback.	1599	use an C<aio_group> together with a feed callback.
976		1600
977	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1601	It's main use is in scripts without an event loop - when you want to stat
978	to queue up more than this number of requests, the next call to the	1602	a lot of files, you can write somehting like this:
979	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
980	function will block until the limit is no longer exceeded.
981		1603
982	The default value is very large, so there is no practical limit on the	1604	IO::AIO::max_outstanding 32;
983	number of outstanding requests.
984		1605
985	You can still queue as many requests as you want. Therefore,	1606	for my $path (...) {
986	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	1607	aio_stat $path , ...;
987	as a stop gap to shield against fatal memory overflow (with large values).	1608	IO::AIO::poll_cb;
		1609	}
		1610
		1611	IO::AIO::flush;
		1612
		1613	The call to C<poll_cb> inside the loop will normally return instantly, but
		1614	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1615	some requests have been handled. This keeps the loop from pushing a large
		1616	number of C<aio_stat> requests onto the queue.
		1617
		1618	The default value for C<max_outstanding> is very large, so there is no
		1619	practical limit on the number of outstanding requests.
988		1620
989	=back	1621	=back
990		1622
		1623	=head3 STATISTICAL INFORMATION
		1624
		1625	=over
		1626
		1627	=item IO::AIO::nreqs
		1628
		1629	Returns the number of requests currently in the ready, execute or pending
		1630	states (i.e. for which their callback has not been invoked yet).
		1631
		1632	Example: wait till there are no outstanding requests anymore:
		1633
		1634	IO::AIO::poll_wait, IO::AIO::poll_cb
		1635	while IO::AIO::nreqs;
		1636
		1637	=item IO::AIO::nready
		1638
		1639	Returns the number of requests currently in the ready state (not yet
		1640	executed).
		1641
		1642	=item IO::AIO::npending
		1643
		1644	Returns the number of requests currently in the pending state (executed,
		1645	but not yet processed by poll_cb).
		1646
		1647	=back
		1648
		1649	=head3 MISCELLANEOUS FUNCTIONS
		1650
		1651	IO::AIO implements some functions that might be useful, but are not
		1652	asynchronous.
		1653
		1654	=over 4
		1655
		1656	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1657
		1658	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1659	but is blocking (this makes most sense if you know the input data is
		1660	likely cached already and the output filehandle is set to non-blocking
		1661	operations).
		1662
		1663	Returns the number of bytes copied, or C<-1> on error.
		1664
		1665	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1666
		1667	Simply calls the C<posix_fadvise> function (see its
		1668	manpage for details). The following advice constants are
		1669	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1670	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1671	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1672
		1673	On systems that do not implement C<posix_fadvise>, this function returns
		1674	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1675
		1676	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1677
		1678	Simply calls the C<posix_madvise> function (see its
		1679	manpage for details). The following advice constants are
		1680	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1681	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1682
		1683	On systems that do not implement C<posix_madvise>, this function returns
		1684	ENOSYS, otherwise the return value of C<posix_madvise>.
		1685
		1686	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1687
		1688	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1689	$scalar (see its manpage for details). The following protect
		1690	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1691	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1692
		1693	On systems that do not implement C<mprotect>, this function returns
		1694	ENOSYS, otherwise the return value of C<mprotect>.
		1695
		1696	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1697
		1698	Memory-maps a file (or anonymous memory range) and attaches it to the
		1699	given C<$scalar>, which will act like a string scalar.
		1700
		1701	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1702	change the string length, and most read-only operations such as copying it
		1703	or searching it with regexes and so on.
		1704
		1705	Anything else is unsafe and will, at best, result in memory leaks.
		1706
		1707	The memory map associated with the C<$scalar> is automatically removed
		1708	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1709	C<IO::AIO::munmap> functions are called.
		1710
		1711	This calls the C<mmap>(2) function internally. See your system's manual
		1712	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1713
		1714	The C<$length> must be larger than zero and smaller than the actual
		1715	filesize.
		1716
		1717	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1718	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1719
		1720	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1721	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1722	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1723	(which is set to C<MAP_ANON> if your system only provides this
		1724	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1725	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1726	C<IO::AIO::MAP_NONBLOCK>
		1727
		1728	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1729
		1730	C<$offset> is the offset from the start of the file - it generally must be
		1731	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1732
		1733	Example:
		1734
		1735	use Digest::MD5;
		1736	use IO::AIO;
		1737
		1738	open my $fh, "<verybigfile"
		1739	or die "$!";
		1740
		1741	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1742	or die "verybigfile: $!";
		1743
		1744	my $fast_md5 = md5 $data;
		1745
		1746	=item IO::AIO::munmap $scalar
		1747
		1748	Removes a previous mmap and undefines the C<$scalar>.
		1749
		1750	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1751
		1752	Calls the C<munlock> function, undoing the effects of a previous
		1753	C<aio_mlock> call (see its description for details).
		1754
		1755	=item IO::AIO::munlockall
		1756
		1757	Calls the C<munlockall> function.
		1758
		1759	On systems that do not implement C<munlockall>, this function returns
		1760	ENOSYS, otherwise the return value of C<munlockall>.
		1761
		1762	=back
		1763
991	=cut	1764	=cut
992		1765
993	# support function to convert a fd into a perl filehandle
994	sub _fd2fh {
995	return undef if $_[0] < 0;
996
997	# try to generate nice filehandles
998	my $sym = "IO::AIO::fd#$_[0]";
999	local *$sym;
1000
1001	open *$sym, "+<&=$_[0]" # usually works under any unix
1002	or open *$sym, "<&=$_[0]" # cygwin needs this
1003	or open *$sym, ">&=$_[0]" # or this
1004	or return undef;
1005
1006	*$sym
1007	}
1008
1009	min_parallel 8;	1766	min_parallel 8;
1010		1767
1011	END {	1768	END { flush }
1012	min_parallel 1;
1013	flush;
1014	};
1015		1769
1016	1;	1770	1;
1017		1771
		1772	=head1 EVENT LOOP INTEGRATION
		1773
		1774	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1775	automatically into many event loops:
		1776
		1777	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1778	use AnyEvent::AIO;
		1779
		1780	You can also integrate IO::AIO manually into many event loops, here are
		1781	some examples of how to do this:
		1782
		1783	# EV integration
		1784	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1785
		1786	# Event integration
		1787	Event->io (fd => IO::AIO::poll_fileno,
		1788	poll => 'r',
		1789	cb => \&IO::AIO::poll_cb);
		1790
		1791	# Glib/Gtk2 integration
		1792	add_watch Glib::IO IO::AIO::poll_fileno,
		1793	in => sub { IO::AIO::poll_cb; 1 };
		1794
		1795	# Tk integration
		1796	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1797	readable => \&IO::AIO::poll_cb);
		1798
		1799	# Danga::Socket integration
		1800	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1801	\&IO::AIO::poll_cb);
		1802
1018	=head2 FORK BEHAVIOUR	1803	=head2 FORK BEHAVIOUR
1019		1804
1020	This module should do "the right thing" when the process using it forks:	1805	Usage of pthreads in a program changes the semantics of fork
		1806	considerably. Specifically, only async-safe functions can be called after
		1807	fork. Perl doesn't know about this, so in general, you cannot call fork
		1808	with defined behaviour in perl. IO::AIO uses pthreads, so this applies,
		1809	but many other extensions and (for inexplicable reasons) perl itself often
		1810	is linked against pthreads, so this limitation applies.
1021		1811
1022	Before the fork, IO::AIO enters a quiescent state where no requests	1812	Some operating systems have extensions that allow safe use of fork, and
1023	can be added in other threads and no results will be processed. After	1813	this module should do "the right thing" on those, and tries on others. At
1024	the fork the parent simply leaves the quiescent state and continues	1814	the time of this writing (2011) only GNU/Linux supports these extensions
1025	request/result processing, while the child frees the request/result queue	1815	to POSIX.
1026	(so that the requests started before the fork will only be handled in the
1027	parent). Threads will be started on demand until the limit set in the
1028	parent process has been reached again.
1029
1030	In short: the parent will, after a short pause, continue as if fork had
1031	not been called, while the child will act as if IO::AIO has not been used
1032	yet.
1033		1816
1034	=head2 MEMORY USAGE	1817	=head2 MEMORY USAGE
1035		1818
1036	Per-request usage:	1819	Per-request usage:
1037		1820
…		…
1039	bytes of memory. In addition, stat requests need a stat buffer (possibly	1822	bytes of memory. In addition, stat requests need a stat buffer (possibly
1040	a few hundred bytes), readdir requires a result buffer and so on. Perl	1823	a few hundred bytes), readdir requires a result buffer and so on. Perl
1041	scalars and other data passed into aio requests will also be locked and	1824	scalars and other data passed into aio requests will also be locked and
1042	will consume memory till the request has entered the done state.	1825	will consume memory till the request has entered the done state.
1043		1826
1044	This is now awfully much, so queuing lots of requests is not usually a	1827	This is not awfully much, so queuing lots of requests is not usually a
1045	problem.	1828	problem.
1046		1829
1047	Per-thread usage:	1830	Per-thread usage:
1048		1831
1049	In the execution phase, some aio requests require more memory for	1832	In the execution phase, some aio requests require more memory for
…		…
1054		1837
1055	Known bugs will be fixed in the next release.	1838	Known bugs will be fixed in the next release.
1056		1839
1057	=head1 SEE ALSO	1840	=head1 SEE ALSO
1058		1841
1059	L<Coro::AIO>.	1842	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1843	more natural syntax.
1060		1844
1061	=head1 AUTHOR	1845	=head1 AUTHOR
1062		1846
1063	Marc Lehmann <schmorp@schmorp.de>	1847	Marc Lehmann <schmorp@schmorp.de>
1064	http://home.schmorp.de/	1848	http://home.schmorp.de/

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