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Revision 1.81 by root, Fri Oct 27 19:17:23 2006 UTC vs.
Revision 1.187 by root, Fri Feb 11 00:05:17 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>).
		36
		37	Asynchronous means that operations that can normally block your program
		38	(e.g. reading from disk) will be done asynchronously: the operation
		39	will still block, but you can do something else in the meantime. This
		40	is extremely useful for programs that need to stay interactive even
		41	when doing heavy I/O (GUI programs, high performance network servers
		42	etc.), but can also be used to easily do operations in parallel that are
		43	normally done sequentially, e.g. stat'ing many files, which is much faster
		44	on a RAID volume or over NFS when you do a number of stat operations
		45	concurrently.
		46
		47	While most of this works on all types of file descriptors (for
		48	example sockets), using these functions on file descriptors that
		49	support nonblocking operation (again, sockets, pipes etc.) is
		50	very inefficient. Use an event loop for that (such as the L<EV>
		51	module): IO::AIO will naturally fit into such an event loop itself.
55		52
56	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
57	requests and signal their completion. You don't need thread support	54	requests and signal their completion. You don't need thread support
58	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
59	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
60	functions available on many operating systems. However, they are often	57	functions available on many operating systems. However, they are often
61	not well-supported or restricted (Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
62	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
63	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
64	using threads anyway.	61	using threads anyway.
65		62
66	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,
67	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
68	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
69	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;
70		109
71	=head1 REQUEST ANATOMY AND LIFETIME	110	=head1 REQUEST ANATOMY AND LIFETIME
72		111
73	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
74	directly visible to Perl.	113	directly visible to Perl.
…		…
116	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
117	(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
118	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
119	result in a runtime error).	158	result in a runtime error).
120		159
		160	=back
		161
121	=cut	162	=cut
122		163
123	package IO::AIO;	164	package IO::AIO;
124		165
125	no warnings;	166	use Carp ();
126	use strict 'vars';	167
		168	use common::sense;
127		169
128	use base 'Exporter';	170	use base 'Exporter';
129		171
130	BEGIN {	172	BEGIN {
131	our $VERSION = '2.0';	173	our $VERSION = '3.72';
132		174
133	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
134	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
135	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	177	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
		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
136	aio_group aio_nop);	183	aio_statvfs);
		184
137	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
138	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139	min_parallel max_parallel nreqs nready npending);	187	min_parallel max_parallel max_idle
		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
140		194
141	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	195	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142		196
143	require XSLoader;	197	require XSLoader;
144	XSLoader::load ("IO::AIO", $VERSION);	198	XSLoader::load ("IO::AIO", $VERSION);
145	}	199	}
146		200
147	=head1 FUNCTIONS	201	=head1 FUNCTIONS
148		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_rename $srcpath, $dstpath, $callback->($status)
		228	aio_mkdir $pathname, $mode, $callback->($status)
		229	aio_rmdir $pathname, $callback->($status)
		230	aio_readdir $pathname, $callback->($entries)
		231	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		232	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		233	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		234	aio_load $path, $data, $callback->($status)
		235	aio_copy $srcpath, $dstpath, $callback->($status)
		236	aio_move $srcpath, $dstpath, $callback->($status)
		237	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		238	aio_rmtree $path, $callback->($status)
		239	aio_sync $callback->($status)
		240	aio_fsync $fh, $callback->($status)
		241	aio_fdatasync $fh, $callback->($status)
		242	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		243	aio_pathsync $path, $callback->($status)
		244	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		245	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		246	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		247	aio_mlockall $flags, $callback->($status)
		248	aio_group $callback->(...)
		249	aio_nop $callback->()
		250
		251	$prev_pri = aioreq_pri [$pri]
		252	aioreq_nice $pri_adjust
		253
		254	IO::AIO::poll_wait
		255	IO::AIO::poll_cb
		256	IO::AIO::poll
		257	IO::AIO::flush
		258	IO::AIO::max_poll_reqs $nreqs
		259	IO::AIO::max_poll_time $seconds
		260	IO::AIO::min_parallel $nthreads
		261	IO::AIO::max_parallel $nthreads
		262	IO::AIO::max_idle $nthreads
		263	IO::AIO::max_outstanding $maxreqs
		264	IO::AIO::nreqs
		265	IO::AIO::nready
		266	IO::AIO::npending
		267
		268	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		269	IO::AIO::fadvise $fh, $offset, $len, $advice
		270	IO::AIO::madvise $scalar, $offset, $length, $advice
		271	IO::AIO::mprotect $scalar, $offset, $length, $protect
		272	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		273	IO::AIO::munlockall
		274
149	=head2 AIO FUNCTIONS	275	=head2 AIO REQUEST FUNCTIONS
150		276
151	All the C<aio_*> calls are more or less thin wrappers around the syscall	277	All the C<aio_*> calls are more or less thin wrappers around the syscall
152	with the same name (sans C<aio_>). The arguments are similar or identical,	278	with the same name (sans C<aio_>). The arguments are similar or identical,
153	and they all accept an additional (and optional) C<$callback> argument	279	and they all accept an additional (and optional) C<$callback> argument
154	which must be a code reference. This code reference will get called with	280	which must be a code reference. This code reference will get called with
155	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	281	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
156	perl, which usually delivers "false") as it's sole argument when the given	282	perl, which usually delivers "false") as its sole argument after the given
157	syscall has been executed asynchronously.	283	syscall has been executed asynchronously.
158		284
159	All functions expecting a filehandle keep a copy of the filehandle	285	All functions expecting a filehandle keep a copy of the filehandle
160	internally until the request has finished.	286	internally until the request has finished.
161		287
162	All requests return objects of type L<IO::AIO::REQ> that allow further	288	All functions return request objects of type L<IO::AIO::REQ> that allow
163	manipulation of those requests while they are in-flight.	289	further manipulation of those requests while they are in-flight.
164		290
165	The pathnames you pass to these routines I<must> be absolute and	291	The pathnames you pass to these routines I<must> be absolute and
166	encoded in byte form. The reason for the former is that at the time the	292	encoded as octets. The reason for the former is that at the time the
167	request is being executed, the current working directory could have	293	request is being executed, the current working directory could have
168	changed. Alternatively, you can make sure that you never change the	294	changed. Alternatively, you can make sure that you never change the
169	current working directory.	295	current working directory anywhere in the program and then use relative
		296	paths.
170		297
171	To encode pathnames to byte form, either make sure you either: a)	298	To encode pathnames as octets, either make sure you either: a) always pass
172	always pass in filenames you got from outside (command line, readdir	299	in filenames you got from outside (command line, readdir etc.) without
173	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	300	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
174	your pathnames to the locale (or other) encoding in effect in the user	301	your pathnames to the locale (or other) encoding in effect in the user
175	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	302	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176	use something else.	303	use something else to ensure your scalar has the correct contents.
		304
		305	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		306	handles correctly whether it is set or not.
177		307
178	=over 4	308	=over 4
179		309
180	=item $prev_pri = aioreq_pri [$pri]	310	=item $prev_pri = aioreq_pri [$pri]
181		311
…		…
201	aio_read $_[0], ..., sub {	331	aio_read $_[0], ..., sub {
202	...	332	...
203	};	333	};
204	};	334	};
205		335
		336
206	=item aioreq_nice $pri_adjust	337	=item aioreq_nice $pri_adjust
207		338
208	Similar to C<aioreq_pri>, but subtracts the given value from the current	339	Similar to C<aioreq_pri>, but subtracts the given value from the current
209	priority, so effects are cumulative.	340	priority, so the effect is cumulative.
		341
210		342
211	=item aio_open $pathname, $flags, $mode, $callback->($fh)	343	=item aio_open $pathname, $flags, $mode, $callback->($fh)
212		344
213	Asynchronously open or create a file and call the callback with a newly	345	Asynchronously open or create a file and call the callback with a newly
214	created filehandle for the file.	346	created filehandle for the file.
…		…
220	list. They are the same as used by C<sysopen>.	352	list. They are the same as used by C<sysopen>.
221		353
222	Likewise, C<$mode> specifies the mode of the newly created file, if it	354	Likewise, C<$mode> specifies the mode of the newly created file, if it
223	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	355	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
224	except that it is mandatory (i.e. use C<0> if you don't create new files,	356	except that it is mandatory (i.e. use C<0> if you don't create new files,
225	and C<0666> or C<0777> if you do).	357	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		358	by the umask in effect then the request is being executed, so better never
		359	change the umask.
226		360
227	Example:	361	Example:
228		362
229	aio_open "/etc/passwd", O_RDONLY, 0, sub {	363	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
230	if ($_[0]) {	364	if ($_[0]) {
231	print "open successful, fh is $_[0]\n";	365	print "open successful, fh is $_[0]\n";
232	...	366	...
233	} else {	367	} else {
234	die "open failed: $!\n";	368	die "open failed: $!\n";
235	}	369	}
236	};	370	};
237		371
		372
238	=item aio_close $fh, $callback->($status)	373	=item aio_close $fh, $callback->($status)
239		374
240	Asynchronously close a file and call the callback with the result	375	Asynchronously close a file and call the callback with the result
241	code. I<WARNING:> although accepted, you should not pass in a perl	376	code.
242	filehandle here, as perl will likely close the file descriptor another
243	time when the filehandle is destroyed. Normally, you can safely call perls
244	C<close> or just let filehandles go out of scope.
245		377
246	This is supposed to be a bug in the API, so that might change. It's	378	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
247	therefore best to avoid this function.	379	closing the file descriptor associated with the filehandle itself.
		380
		381	Therefore, C<aio_close> will not close the filehandle - instead it will
		382	use dup2 to overwrite the file descriptor with the write-end of a pipe
		383	(the pipe fd will be created on demand and will be cached).
		384
		385	Or in other words: the file descriptor will be closed, but it will not be
		386	free for reuse until the perl filehandle is closed.
		387
		388	=cut
248		389
249	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	390	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
250		391
251	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	392	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
252		393
253	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	394	Reads or writes C<$length> bytes from or to the specified C<$fh> and
254	into the scalar given by C<data> and offset C<dataoffset> and calls the	395	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
255	callback without the actual number of bytes read (or -1 on error, just	396	and calls the callback without the actual number of bytes read (or -1 on
256	like the syscall).	397	error, just like the syscall).
		398
		399	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		400	offset plus the actual number of bytes read.
		401
		402	If C<$offset> is undefined, then the current file descriptor offset will
		403	be used (and updated), otherwise the file descriptor offset will not be
		404	changed by these calls.
		405
		406	If C<$length> is undefined in C<aio_write>, use the remaining length of
		407	C<$data>.
		408
		409	If C<$dataoffset> is less than zero, it will be counted from the end of
		410	C<$data>.
257		411
258	The C<$data> scalar I<MUST NOT> be modified in any way while the request	412	The C<$data> scalar I<MUST NOT> be modified in any way while the request
259	is outstanding. Modifying it can result in segfaults or WW3 (if the	413	is outstanding. Modifying it can result in segfaults or World War III (if
260	necessary/optional hardware is installed).	414	the necessary/optional hardware is installed).
261		415
262	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	416	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
263	offset C<0> within the scalar:	417	offset C<0> within the scalar:
264		418
265	aio_read $fh, 7, 15, $buffer, 0, sub {	419	aio_read $fh, 7, 15, $buffer, 0, sub {
266	$_[0] > 0 or die "read error: $!";	420	$_[0] > 0 or die "read error: $!";
267	print "read $_[0] bytes: <$buffer>\n";	421	print "read $_[0] bytes: <$buffer>\n";
268	};	422	};
269		423
270	=item aio_move $srcpath, $dstpath, $callback->($status)
271
272	Try to move the I<file> (directories not supported as either source or
273	destination) from C<$srcpath> to C<$dstpath> and call the callback with
274	the C<0> (error) or C<-1> ok.
275
276	This is a composite request that tries to rename(2) the file first. If
277	rename files with C<EXDEV>, it creates the destination file with mode 0200
278	and copies the contents of the source file into it using C<aio_sendfile>,
279	followed by restoring atime, mtime, access mode and uid/gid, in that
280	order, and unlinking the C<$srcpath>.
281
282	If an error occurs, the partial destination file will be unlinked, if
283	possible, except when setting atime, mtime, access mode and uid/gid, where
284	errors are being ignored.
285
286	=cut
287
288	sub aio_move($$$) {
289	my ($src, $dst, $cb) = @_;
290
291	my $pri = aioreq_pri;
292	my $grp = aio_group $cb;
293
294	aioreq_pri $pri;
295	add $grp aio_rename $src, $dst, sub {
296	if ($_[0] && $! == EXDEV) {
297	aioreq_pri $pri;
298	add $grp aio_open $src, O_RDONLY, 0, sub {
299	if (my $src_fh = $_[0]) {
300	my @stat = stat $src_fh;
301
302	aioreq_pri $pri;
303	add $grp aio_open $dst, O_WRONLY, 0200, sub {
304	if (my $dst_fh = $_[0]) {
305	aioreq_pri $pri;
306	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
307	close $src_fh;
308
309	if ($_[0] == $stat[7]) {
310	utime $stat[8], $stat[9], $dst;
311	chmod $stat[2] & 07777, $dst_fh;
312	chown $stat[4], $stat[5], $dst_fh;
313	close $dst_fh;
314
315	aioreq_pri $pri;
316	add $grp aio_unlink $src, sub {
317	$grp->result ($_[0]);
318	};
319	} else {
320	my $errno = $!;
321	aioreq_pri $pri;
322	add $grp aio_unlink $dst, sub {
323	$! = $errno;
324	$grp->result (-1);
325	};
326	}
327	};
328	} else {
329	$grp->result (-1);
330	}
331	},
332
333	} else {
334	$grp->result (-1);
335	}
336	};
337	} else {
338	$grp->result ($_[0]);
339	}
340	};
341
342	$grp
343	}
344		424
345	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	425	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
346		426
347	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	427	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
348	reading at byte offset C<$in_offset>, and starts writing at the current	428	reading at byte offset C<$in_offset>, and starts writing at the current
349	file offset of C<$out_fh>. Because of that, it is not safe to issue more	429	file offset of C<$out_fh>. Because of that, it is not safe to issue more
350	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	430	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
351	other.	431	other.
352		432
		433	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		434	are written, and there is no way to find out how many bytes have been read
		435	from C<aio_sendfile> alone, as C<aio_sendfile> only provides the number of
		436	bytes written to C<$out_fh>. Only if the result value equals C<$length>
		437	one can assume that C<$length> bytes have been read.
		438
		439	Unlike with other C<aio_> functions, it makes a lot of sense to use
		440	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		441	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		442	the socket I/O will be non-blocking. Note, however, that you can run into
		443	a trap where C<aio_sendfile> reads some data with readahead, then fails
		444	to write all data, and when the socket is ready the next time, the data
		445	in the cache is already lost, forcing C<aio_sendfile> to again hit the
		446	disk. Explicit C<aio_read> + C<aio_write> let's you control resource usage
		447	much better.
		448
353	This call tries to make use of a native C<sendfile> syscall to provide	449	This call tries to make use of a native C<sendfile> syscall to provide
354	zero-copy operation. For this to work, C<$out_fh> should refer to a	450	zero-copy operation. For this to work, C<$out_fh> should refer to a
355	socket, and C<$in_fh> should refer to mmap'able file.	451	socket, and C<$in_fh> should refer to an mmap'able file.
356		452
357	If the native sendfile call fails or is not implemented, it will be	453	If a native sendfile cannot be found or it fails with C<ENOSYS>,
		454	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,
358	emulated, so you can call C<aio_sendfile> on any type of filehandle	455	it will be emulated, so you can call C<aio_sendfile> on any type of
359	regardless of the limitations of the operating system.	456	filehandle regardless of the limitations of the operating system.
360		457
361	Please note, however, that C<aio_sendfile> can read more bytes from
362	C<$in_fh> than are written, and there is no way to find out how many
363	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
364	provides the number of bytes written to C<$out_fh>. Only if the result
365	value equals C<$length> one can assume that C<$length> bytes have been
366	read.
367		458
368	=item aio_readahead $fh,$offset,$length, $callback->($retval)	459	=item aio_readahead $fh,$offset,$length, $callback->($retval)
369		460
370	C<aio_readahead> populates the page cache with data from a file so that	461	C<aio_readahead> populates the page cache with data from a file so that
371	subsequent reads from that file will not block on disk I/O. The C<$offset>	462	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
377	file. The current file offset of the file is left unchanged.	468	file. The current file offset of the file is left unchanged.
378		469
379	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	470	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
380	emulated by simply reading the data, which would have a similar effect.	471	emulated by simply reading the data, which would have a similar effect.
381		472
		473
382	=item aio_stat $fh_or_path, $callback->($status)	474	=item aio_stat $fh_or_path, $callback->($status)
383		475
384	=item aio_lstat $fh, $callback->($status)	476	=item aio_lstat $fh, $callback->($status)
385		477
386	Works like perl's C<stat> or C<lstat> in void context. The callback will	478	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
391	for an explanation.	483	for an explanation.
392		484
393	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	485	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
394	error when stat'ing a large file, the results will be silently truncated	486	error when stat'ing a large file, the results will be silently truncated
395	unless perl itself is compiled with large file support.	487	unless perl itself is compiled with large file support.
		488
		489	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		490	following constants and functions (if not implemented, the constants will
		491	be C<0> and the functions will either C<croak> or fall back on traditional
		492	behaviour).
		493
		494	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		495	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		496	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
396		497
397	Example: Print the length of F</etc/passwd>:	498	Example: Print the length of F</etc/passwd>:
398		499
399	aio_stat "/etc/passwd", sub {	500	aio_stat "/etc/passwd", sub {
400	$_[0] and die "stat failed: $!";	501	$_[0] and die "stat failed: $!";
401	print "size is ", -s _, "\n";	502	print "size is ", -s _, "\n";
402	};	503	};
403		504
		505
		506	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		507
		508	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		509	whether a file handle or path was passed.
		510
		511	On success, the callback is passed a hash reference with the following
		512	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		513	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		514	is passed.
		515
		516	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		517	C<ST_NOSUID>.
		518
		519	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		520	their correct value when available, or to C<0> on systems that do
		521	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		522	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		523	C<ST_NODIRATIME> and C<ST_RELATIME>.
		524
		525	Example: stat C</wd> and dump out the data if successful.
		526
		527	aio_statvfs "/wd", sub {
		528	my $f = $_[0]
		529	or die "statvfs: $!";
		530
		531	use Data::Dumper;
		532	say Dumper $f;
		533	};
		534
		535	# result:
		536	{
		537	bsize => 1024,
		538	bfree => 4333064312,
		539	blocks => 10253828096,
		540	files => 2050765568,
		541	flag => 4096,
		542	favail => 2042092649,
		543	bavail => 4333064312,
		544	ffree => 2042092649,
		545	namemax => 255,
		546	frsize => 1024,
		547	fsid => 1810
		548	}
		549
		550
		551	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		552
		553	Works like perl's C<utime> function (including the special case of $atime
		554	and $mtime being undef). Fractional times are supported if the underlying
		555	syscalls support them.
		556
		557	When called with a pathname, uses utimes(2) if available, otherwise
		558	utime(2). If called on a file descriptor, uses futimes(2) if available,
		559	otherwise returns ENOSYS, so this is not portable.
		560
		561	Examples:
		562
		563	# set atime and mtime to current time (basically touch(1)):
		564	aio_utime "path", undef, undef;
		565	# set atime to current time and mtime to beginning of the epoch:
		566	aio_utime "path", time, undef; # undef==0
		567
		568
		569	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		570
		571	Works like perl's C<chown> function, except that C<undef> for either $uid
		572	or $gid is being interpreted as "do not change" (but -1 can also be used).
		573
		574	Examples:
		575
		576	# same as "chown root path" in the shell:
		577	aio_chown "path", 0, -1;
		578	# same as above:
		579	aio_chown "path", 0, undef;
		580
		581
		582	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		583
		584	Works like truncate(2) or ftruncate(2).
		585
		586
		587	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		588
		589	Works like perl's C<chmod> function.
		590
		591
404	=item aio_unlink $pathname, $callback->($status)	592	=item aio_unlink $pathname, $callback->($status)
405		593
406	Asynchronously unlink (delete) a file and call the callback with the	594	Asynchronously unlink (delete) a file and call the callback with the
407	result code.	595	result code.
408		596
		597
		598	=item aio_mknod $path, $mode, $dev, $callback->($status)
		599
		600	[EXPERIMENTAL]
		601
		602	Asynchronously create a device node (or fifo). See mknod(2).
		603
		604	The only (POSIX-) portable way of calling this function is:
		605
		606	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		607
		608	See C<aio_stat> for info about some potentially helpful extra constants
		609	and functions.
		610
409	=item aio_link $srcpath, $dstpath, $callback->($status)	611	=item aio_link $srcpath, $dstpath, $callback->($status)
410		612
411	Asynchronously create a new link to the existing object at C<$srcpath> at	613	Asynchronously create a new link to the existing object at C<$srcpath> at
412	the path C<$dstpath> and call the callback with the result code.	614	the path C<$dstpath> and call the callback with the result code.
413		615
		616
414	=item aio_symlink $srcpath, $dstpath, $callback->($status)	617	=item aio_symlink $srcpath, $dstpath, $callback->($status)
415		618
416	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	619	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
417	the path C<$dstpath> and call the callback with the result code.	620	the path C<$dstpath> and call the callback with the result code.
418		621
		622
		623	=item aio_readlink $path, $callback->($link)
		624
		625	Asynchronously read the symlink specified by C<$path> and pass it to
		626	the callback. If an error occurs, nothing or undef gets passed to the
		627	callback.
		628
		629
419	=item aio_rename $srcpath, $dstpath, $callback->($status)	630	=item aio_rename $srcpath, $dstpath, $callback->($status)
420		631
421	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	632	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
422	rename(2) and call the callback with the result code.	633	rename(2) and call the callback with the result code.
423		634
		635
		636	=item aio_mkdir $pathname, $mode, $callback->($status)
		637
		638	Asynchronously mkdir (create) a directory and call the callback with
		639	the result code. C<$mode> will be modified by the umask at the time the
		640	request is executed, so do not change your umask.
		641
		642
424	=item aio_rmdir $pathname, $callback->($status)	643	=item aio_rmdir $pathname, $callback->($status)
425		644
426	Asynchronously rmdir (delete) a directory and call the callback with the	645	Asynchronously rmdir (delete) a directory and call the callback with the
427	result code.	646	result code.
		647
428		648
429	=item aio_readdir $pathname, $callback->($entries)	649	=item aio_readdir $pathname, $callback->($entries)
430		650
431	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	651	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
432	directory (i.e. opendir + readdir + closedir). The entries will not be	652	directory (i.e. opendir + readdir + closedir). The entries will not be
433	sorted, and will B<NOT> include the C<.> and C<..> entries.	653	sorted, and will B<NOT> include the C<.> and C<..> entries.
434		654
435	The callback a single argument which is either C<undef> or an array-ref	655	The callback is passed a single argument which is either C<undef> or an
436	with the filenames.	656	array-ref with the filenames.
		657
		658
		659	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		660
		661	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		662	behaviour and output format. In case of an error, C<$entries> will be
		663	C<undef>.
		664
		665	The flags are a combination of the following constants, ORed together (the
		666	flags will also be passed to the callback, possibly modified):
		667
		668	=over 4
		669
		670	=item IO::AIO::READDIR_DENTS
		671
		672	When this flag is off, then the callback gets an arrayref with of names
		673	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		674	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		675	entry in more detail.
		676
		677	C<$name> is the name of the entry.
		678
		679	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		680
		681	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		682	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		683	C<IO::AIO::DT_WHT>.
		684
		685	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		686	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		687	scalars are read-only: you can not modify them.
		688
		689	C<$inode> is the inode number (which might not be exact on systems with 64
		690	bit inode numbers and 32 bit perls). This field has unspecified content on
		691	systems that do not deliver the inode information.
		692
		693	=item IO::AIO::READDIR_DIRS_FIRST
		694
		695	When this flag is set, then the names will be returned in an order where
		696	likely directories come first. This is useful when you need to quickly
		697	find directories, or you want to find all directories while avoiding to
		698	stat() each entry.
		699
		700	If the system returns type information in readdir, then this is used
		701	to find directories directly. Otherwise, likely directories are files
		702	beginning with ".", or otherwise files with no dots, of which files with
		703	short names are tried first.
		704
		705	=item IO::AIO::READDIR_STAT_ORDER
		706
		707	When this flag is set, then the names will be returned in an order
		708	suitable for stat()'ing each one. That is, when you plan to stat()
		709	all files in the given directory, then the returned order will likely
		710	be fastest.
		711
		712	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		713	the likely dirs come first, resulting in a less optimal stat order.
		714
		715	=item IO::AIO::READDIR_FOUND_UNKNOWN
		716
		717	This flag should not be set when calling C<aio_readdirx>. Instead, it
		718	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		719	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		720	C<$type>'s are known, which can be used to speed up some algorithms.
		721
		722	=back
		723
		724
		725	=item aio_load $path, $data, $callback->($status)
		726
		727	This is a composite request that tries to fully load the given file into
		728	memory. Status is the same as with aio_read.
		729
		730	=cut
		731
		732	sub aio_load($$;$) {
		733	my ($path, undef, $cb) = @_;
		734	my $data = \$_[1];
		735
		736	my $pri = aioreq_pri;
		737	my $grp = aio_group $cb;
		738
		739	aioreq_pri $pri;
		740	add $grp aio_open $path, O_RDONLY, 0, sub {
		741	my $fh = shift
		742	or return $grp->result (-1);
		743
		744	aioreq_pri $pri;
		745	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		746	$grp->result ($_[0]);
		747	};
		748	};
		749
		750	$grp
		751	}
		752
		753	=item aio_copy $srcpath, $dstpath, $callback->($status)
		754
		755	Try to copy the I<file> (directories not supported as either source or
		756	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		757	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		758
		759	This is a composite request that creates the destination file with
		760	mode 0200 and copies the contents of the source file into it using
		761	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		762	uid/gid, in that order.
		763
		764	If an error occurs, the partial destination file will be unlinked, if
		765	possible, except when setting atime, mtime, access mode and uid/gid, where
		766	errors are being ignored.
		767
		768	=cut
		769
		770	sub aio_copy($$;$) {
		771	my ($src, $dst, $cb) = @_;
		772
		773	my $pri = aioreq_pri;
		774	my $grp = aio_group $cb;
		775
		776	aioreq_pri $pri;
		777	add $grp aio_open $src, O_RDONLY, 0, sub {
		778	if (my $src_fh = $_[0]) {
		779	my @stat = stat $src_fh; # hmm, might block over nfs?
		780
		781	aioreq_pri $pri;
		782	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		783	if (my $dst_fh = $_[0]) {
		784	aioreq_pri $pri;
		785	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		786	if ($_[0] == $stat[7]) {
		787	$grp->result (0);
		788	close $src_fh;
		789
		790	my $ch = sub {
		791	aioreq_pri $pri;
		792	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		793	aioreq_pri $pri;
		794	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		795	aioreq_pri $pri;
		796	add $grp aio_close $dst_fh;
		797	}
		798	};
		799	};
		800
		801	aioreq_pri $pri;
		802	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		803	if ($_[0] < 0 && $! == ENOSYS) {
		804	aioreq_pri $pri;
		805	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		806	} else {
		807	$ch->();
		808	}
		809	};
		810	} else {
		811	$grp->result (-1);
		812	close $src_fh;
		813	close $dst_fh;
		814
		815	aioreq $pri;
		816	add $grp aio_unlink $dst;
		817	}
		818	};
		819	} else {
		820	$grp->result (-1);
		821	}
		822	},
		823
		824	} else {
		825	$grp->result (-1);
		826	}
		827	};
		828
		829	$grp
		830	}
		831
		832	=item aio_move $srcpath, $dstpath, $callback->($status)
		833
		834	Try to move the I<file> (directories not supported as either source or
		835	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		836	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		837
		838	This is a composite request that tries to rename(2) the file first; if
		839	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		840	that is successful, unlinks the C<$srcpath>.
		841
		842	=cut
		843
		844	sub aio_move($$;$) {
		845	my ($src, $dst, $cb) = @_;
		846
		847	my $pri = aioreq_pri;
		848	my $grp = aio_group $cb;
		849
		850	aioreq_pri $pri;
		851	add $grp aio_rename $src, $dst, sub {
		852	if ($_[0] && $! == EXDEV) {
		853	aioreq_pri $pri;
		854	add $grp aio_copy $src, $dst, sub {
		855	$grp->result ($_[0]);
		856
		857	if (!$_[0]) {
		858	aioreq_pri $pri;
		859	add $grp aio_unlink $src;
		860	}
		861	};
		862	} else {
		863	$grp->result ($_[0]);
		864	}
		865	};
		866
		867	$grp
		868	}
437		869
438	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	870	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
439		871
440	Scans a directory (similar to C<aio_readdir>) but additionally tries to	872	Scans a directory (similar to C<aio_readdir>) but additionally tries to
441	efficiently separate the entries of directory C<$path> into two sets of	873	efficiently separate the entries of directory C<$path> into two sets of
…		…
460		892
461	Implementation notes.	893	Implementation notes.
462		894
463	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	895	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
464		896
		897	If readdir returns file type information, then this is used directly to
		898	find directories.
		899
465	After reading the directory, the modification time, size etc. of the	900	Otherwise, after reading the directory, the modification time, size etc.
466	directory before and after the readdir is checked, and if they match (and	901	of the directory before and after the readdir is checked, and if they
467	isn't the current time), the link count will be used to decide how many	902	match (and isn't the current time), the link count will be used to decide
468	entries are directories (if >= 2). Otherwise, no knowledge of the number	903	how many entries are directories (if >= 2). Otherwise, no knowledge of the
469	of subdirectories will be assumed.	904	number of subdirectories will be assumed.
470		905
471	Then entries will be sorted into likely directories (everything without	906	Then entries will be sorted into likely directories a non-initial dot
472	a non-initial dot currently) and likely non-directories (everything	907	currently) and likely non-directories (see C<aio_readdirx>). Then every
473	else). Then every entry plus an appended C</.> will be C<stat>'ed,	908	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
474	likely directories first. If that succeeds, it assumes that the entry	909	in order of their inode numbers. If that succeeds, it assumes that the
475	is a directory or a symlink to directory (which will be checked	910	entry is a directory or a symlink to directory (which will be checked
476	seperately). This is often faster than stat'ing the entry itself because	911	seperately). This is often faster than stat'ing the entry itself because
477	filesystems might detect the type of the entry without reading the inode	912	filesystems might detect the type of the entry without reading the inode
478	data (e.g. ext2fs filetype feature).	913	data (e.g. ext2fs filetype feature), even on systems that cannot return
		914	the filetype information on readdir.
479		915
480	If the known number of directories (link count - 2) has been reached, the	916	If the known number of directories (link count - 2) has been reached, the
481	rest of the entries is assumed to be non-directories.	917	rest of the entries is assumed to be non-directories.
482		918
483	This only works with certainty on POSIX (= UNIX) filesystems, which	919	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
487	as those tend to return 0 or 1 as link counts, which disables the	923	as those tend to return 0 or 1 as link counts, which disables the
488	directory counting heuristic.	924	directory counting heuristic.
489		925
490	=cut	926	=cut
491		927
492	sub aio_scandir($$$) {	928	sub aio_scandir($$;$) {
493	my ($path, $maxreq, $cb) = @_;	929	my ($path, $maxreq, $cb) = @_;
494		930
495	my $pri = aioreq_pri;	931	my $pri = aioreq_pri;
496		932
497	my $grp = aio_group $cb;	933	my $grp = aio_group $cb;
…		…
505	my $now = time;	941	my $now = time;
506	my $hash1 = join ":", (stat _)[0,1,3,7,9];	942	my $hash1 = join ":", (stat _)[0,1,3,7,9];
507		943
508	# read the directory entries	944	# read the directory entries
509	aioreq_pri $pri;	945	aioreq_pri $pri;
510	add $grp aio_readdir $path, sub {	946	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
511	my $entries = shift	947	my $entries = shift
512	or return $grp->result ();	948	or return $grp->result ();
513		949
514	# stat the dir another time	950	# stat the dir another time
515	aioreq_pri $pri;	951	aioreq_pri $pri;
…		…
521	# take the slow route if anything looks fishy	957	# take the slow route if anything looks fishy
522	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	958	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
523	$ndirs = -1;	959	$ndirs = -1;
524	} else {	960	} else {
525	# if nlink == 2, we are finished	961	# if nlink == 2, we are finished
526	# on non-posix-fs's, we rely on nlink < 2	962	# for non-posix-fs's, we rely on nlink < 2
527	$ndirs = (stat _)[3] - 2	963	$ndirs = (stat _)[3] - 2
528	or return $grp->result ([], $entries);	964	or return $grp->result ([], $entries);
529	}	965	}
530		966
531	# sort into likely dirs and likely nondirs
532	# dirs == files without ".", short entries first
533	$entries = [map $_->[0],
534	sort { $b->[1] cmp $a->[1] }
535	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
536	@$entries];
537
538	my (@dirs, @nondirs);	967	my (@dirs, @nondirs);
539		968
540	my $statgrp = add $grp aio_group sub {	969	my $statgrp = add $grp aio_group sub {
541	$grp->result (\@dirs, \@nondirs);	970	$grp->result (\@dirs, \@nondirs);
542	};	971	};
543		972
544	limit $statgrp $maxreq;	973	limit $statgrp $maxreq;
545	feed $statgrp sub {	974	feed $statgrp sub {
546	return unless @$entries;	975	return unless @$entries;
547	my $entry = pop @$entries;	976	my $entry = shift @$entries;
548		977
549	aioreq_pri $pri;	978	aioreq_pri $pri;
550	add $statgrp aio_stat "$path/$entry/.", sub {	979	add $statgrp aio_stat "$path/$entry/.", sub {
551	if ($_[0] < 0) {	980	if ($_[0] < 0) {
552	push @nondirs, $entry;	981	push @nondirs, $entry;
…		…
573	};	1002	};
574		1003
575	$grp	1004	$grp
576	}	1005	}
577		1006
		1007	=item aio_rmtree $path, $callback->($status)
		1008
		1009	Delete a directory tree starting (and including) C<$path>, return the
		1010	status of the final C<rmdir> only. This is a composite request that
		1011	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		1012	everything else.
		1013
		1014	=cut
		1015
		1016	sub aio_rmtree;
		1017	sub aio_rmtree($;$) {
		1018	my ($path, $cb) = @_;
		1019
		1020	my $pri = aioreq_pri;
		1021	my $grp = aio_group $cb;
		1022
		1023	aioreq_pri $pri;
		1024	add $grp aio_scandir $path, 0, sub {
		1025	my ($dirs, $nondirs) = @_;
		1026
		1027	my $dirgrp = aio_group sub {
		1028	add $grp aio_rmdir $path, sub {
		1029	$grp->result ($_[0]);
		1030	};
		1031	};
		1032
		1033	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1034	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1035
		1036	add $grp $dirgrp;
		1037	};
		1038
		1039	$grp
		1040	}
		1041
		1042	=item aio_sync $callback->($status)
		1043
		1044	Asynchronously call sync and call the callback when finished.
		1045
578	=item aio_fsync $fh, $callback->($status)	1046	=item aio_fsync $fh, $callback->($status)
579		1047
580	Asynchronously call fsync on the given filehandle and call the callback	1048	Asynchronously call fsync on the given filehandle and call the callback
581	with the fsync result code.	1049	with the fsync result code.
582		1050
…		…
585	Asynchronously call fdatasync on the given filehandle and call the	1053	Asynchronously call fdatasync on the given filehandle and call the
586	callback with the fdatasync result code.	1054	callback with the fdatasync result code.
587		1055
588	If this call isn't available because your OS lacks it or it couldn't be	1056	If this call isn't available because your OS lacks it or it couldn't be
589	detected, it will be emulated by calling C<fsync> instead.	1057	detected, it will be emulated by calling C<fsync> instead.
		1058
		1059	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1060
		1061	Sync the data portion of the file specified by C<$offset> and C<$length>
		1062	to disk (but NOT the metadata), by calling the Linux-specific
		1063	sync_file_range call. If sync_file_range is not available or it returns
		1064	ENOSYS, then fdatasync or fsync is being substituted.
		1065
		1066	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1067	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1068	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1069	manpage for details.
		1070
		1071	=item aio_pathsync $path, $callback->($status)
		1072
		1073	This request tries to open, fsync and close the given path. This is a
		1074	composite request intended to sync directories after directory operations
		1075	(E.g. rename). This might not work on all operating systems or have any
		1076	specific effect, but usually it makes sure that directory changes get
		1077	written to disc. It works for anything that can be opened for read-only,
		1078	not just directories.
		1079
		1080	Future versions of this function might fall back to other methods when
		1081	C<fsync> on the directory fails (such as calling C<sync>).
		1082
		1083	Passes C<0> when everything went ok, and C<-1> on error.
		1084
		1085	=cut
		1086
		1087	sub aio_pathsync($;$) {
		1088	my ($path, $cb) = @_;
		1089
		1090	my $pri = aioreq_pri;
		1091	my $grp = aio_group $cb;
		1092
		1093	aioreq_pri $pri;
		1094	add $grp aio_open $path, O_RDONLY, 0, sub {
		1095	my ($fh) = @_;
		1096	if ($fh) {
		1097	aioreq_pri $pri;
		1098	add $grp aio_fsync $fh, sub {
		1099	$grp->result ($_[0]);
		1100
		1101	aioreq_pri $pri;
		1102	add $grp aio_close $fh;
		1103	};
		1104	} else {
		1105	$grp->result (-1);
		1106	}
		1107	};
		1108
		1109	$grp
		1110	}
		1111
		1112	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1113
		1114	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1115	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1116	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1117	scalar must only be modified in-place while an aio operation is pending on
		1118	it).
		1119
		1120	It calls the C<msync> function of your OS, if available, with the memory
		1121	area starting at C<$offset> in the string and ending C<$length> bytes
		1122	later. If C<$length> is negative, counts from the end, and if C<$length>
		1123	is C<undef>, then it goes till the end of the string. The flags can be
		1124	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1125	C<IO::AIO::MS_SYNC>.
		1126
		1127	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1128
		1129	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1130	scalars.
		1131
		1132	It touches (reads or writes) all memory pages in the specified
		1133	range inside the scalar. All caveats and parameters are the same
		1134	as for C<aio_msync>, above, except for flags, which must be either
		1135	C<0> (which reads all pages and ensures they are instantiated) or
		1136	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1137	writing an octet from it, which dirties the page).
		1138
		1139	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1140
		1141	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1142	scalars.
		1143
		1144	It reads in all the pages of the underlying storage into memory (if any)
		1145	and locks them, so they are not getting swapped/paged out or removed.
		1146
		1147	If C<$length> is undefined, then the scalar will be locked till the end.
		1148
		1149	On systems that do not implement C<mlock>, this function returns C<-1>
		1150	and sets errno to C<ENOSYS>.
		1151
		1152	Note that the corresponding C<munlock> is synchronous and is
		1153	documented under L<MISCELLANEOUS FUNCTIONS>.
		1154
		1155	Example: open a file, mmap and mlock it - both will be undone when
		1156	C<$data> gets destroyed.
		1157
		1158	open my $fh, "<", $path or die "$path: $!";
		1159	my $data;
		1160	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1161	aio_mlock $data; # mlock in background
		1162
		1163	=item aio_mlockall $flags, $callback->($status)
		1164
		1165	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1166	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1167
		1168	On systems that do not implement C<mlockall>, this function returns C<-1>
		1169	and sets errno to C<ENOSYS>.
		1170
		1171	Note that the corresponding C<munlockall> is synchronous and is
		1172	documented under L<MISCELLANEOUS FUNCTIONS>.
		1173
		1174	Example: asynchronously lock all current and future pages into memory.
		1175
		1176	aio_mlockall IO::AIO::MCL_FUTURE;
590		1177
591	=item aio_group $callback->(...)	1178	=item aio_group $callback->(...)
592		1179
593	This is a very special aio request: Instead of doing something, it is a	1180	This is a very special aio request: Instead of doing something, it is a
594	container for other aio requests, which is useful if you want to bundle	1181	container for other aio requests, which is useful if you want to bundle
…		…
644	=item cancel $req	1231	=item cancel $req
645		1232
646	Cancels the request, if possible. Has the effect of skipping execution	1233	Cancels the request, if possible. Has the effect of skipping execution
647	when entering the B<execute> state and skipping calling the callback when	1234	when entering the B<execute> state and skipping calling the callback when
648	entering the the B<result> state, but will leave the request otherwise	1235	entering the the B<result> state, but will leave the request otherwise
649	untouched. That means that requests that currently execute will not be	1236	untouched (with the exception of readdir). That means that requests that
650	stopped and resources held by the request will not be freed prematurely.	1237	currently execute will not be stopped and resources held by the request
		1238	will not be freed prematurely.
651		1239
652	=item cb $req $callback->(...)	1240	=item cb $req $callback->(...)
653		1241
654	Replace (or simply set) the callback registered to the request.	1242	Replace (or simply set) the callback registered to the request.
655		1243
…		…
706	Their lifetime, simplified, looks like this: when they are empty, they	1294	Their lifetime, simplified, looks like this: when they are empty, they
707	will finish very quickly. If they contain only requests that are in the	1295	will finish very quickly. If they contain only requests that are in the
708	C<done> state, they will also finish. Otherwise they will continue to	1296	C<done> state, they will also finish. Otherwise they will continue to
709	exist.	1297	exist.
710		1298
711	That means after creating a group you have some time to add requests. And	1299	That means after creating a group you have some time to add requests
712	in the callbacks of those requests, you can add further requests to the	1300	(precisely before the callback has been invoked, which is only done within
713	group. And only when all those requests have finished will the the group	1301	the C<poll_cb>). And in the callbacks of those requests, you can add
714	itself finish.	1302	further requests to the group. And only when all those requests have
		1303	finished will the the group itself finish.
715		1304
716	=over 4	1305	=over 4
717		1306
718	=item add $grp ...	1307	=item add $grp ...
719		1308
…		…
728	=item $grp->cancel_subs	1317	=item $grp->cancel_subs
729		1318
730	Cancel all subrequests and clears any feeder, but not the group request	1319	Cancel all subrequests and clears any feeder, but not the group request
731	itself. Useful when you queued a lot of events but got a result early.	1320	itself. Useful when you queued a lot of events but got a result early.
732		1321
		1322	The group request will finish normally (you cannot add requests to the
		1323	group).
		1324
733	=item $grp->result (...)	1325	=item $grp->result (...)
734		1326
735	Set the result value(s) that will be passed to the group callback when all	1327	Set the result value(s) that will be passed to the group callback when all
736	subrequests have finished and set thre groups errno to the current value	1328	subrequests have finished and set the groups errno to the current value
737	of errno (just like calling C<errno> without an error number). By default,	1329	of errno (just like calling C<errno> without an error number). By default,
738	no argument will be passed and errno is zero.	1330	no argument will be passed and errno is zero.
739		1331
740	=item $grp->errno ([$errno])	1332	=item $grp->errno ([$errno])
741		1333
…		…
752	=item feed $grp $callback->($grp)	1344	=item feed $grp $callback->($grp)
753		1345
754	Sets a feeder/generator on this group: every group can have an attached	1346	Sets a feeder/generator on this group: every group can have an attached
755	generator that generates requests if idle. The idea behind this is that,	1347	generator that generates requests if idle. The idea behind this is that,
756	although you could just queue as many requests as you want in a group,	1348	although you could just queue as many requests as you want in a group,
757	this might starve other requests for a potentially long time. For	1349	this might starve other requests for a potentially long time. For example,
758	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1350	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
759	requests, delaying any later requests for a long time.	1351	delaying any later requests for a long time.
760		1352
761	To avoid this, and allow incremental generation of requests, you can	1353	To avoid this, and allow incremental generation of requests, you can
762	instead a group and set a feeder on it that generates those requests. The	1354	instead a group and set a feeder on it that generates those requests. The
763	feed callback will be called whenever there are few enough (see C<limit>,	1355	feed callback will be called whenever there are few enough (see C<limit>,
764	below) requests active in the group itself and is expected to queue more	1356	below) requests active in the group itself and is expected to queue more
…		…
768	not impose any limits).	1360	not impose any limits).
769		1361
770	If the feed does not queue more requests when called, it will be	1362	If the feed does not queue more requests when called, it will be
771	automatically removed from the group.	1363	automatically removed from the group.
772		1364
773	If the feed limit is C<0>, it will be set to C<2> automatically.	1365	If the feed limit is C<0> when this method is called, it will be set to
		1366	C<2> automatically.
774		1367
775	Example:	1368	Example:
776		1369
777	# stat all files in @files, but only ever use four aio requests concurrently:	1370	# stat all files in @files, but only ever use four aio requests concurrently:
778		1371
…		…
790	Sets the feeder limit for the group: The feeder will be called whenever	1383	Sets the feeder limit for the group: The feeder will be called whenever
791	the group contains less than this many requests.	1384	the group contains less than this many requests.
792		1385
793	Setting the limit to C<0> will pause the feeding process.	1386	Setting the limit to C<0> will pause the feeding process.
794		1387
		1388	The default value for the limit is C<0>, but note that setting a feeder
		1389	automatically bumps it up to C<2>.
		1390
795	=back	1391	=back
796		1392
797	=head2 SUPPORT FUNCTIONS	1393	=head2 SUPPORT FUNCTIONS
798		1394
		1395	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1396
799	=over 4	1397	=over 4
800		1398
801	=item $fileno = IO::AIO::poll_fileno	1399	=item $fileno = IO::AIO::poll_fileno
802		1400
803	Return the I<request result pipe file descriptor>. This filehandle must be	1401	Return the I<request result pipe file descriptor>. This filehandle must be
804	polled for reading by some mechanism outside this module (e.g. Event or	1402	polled for reading by some mechanism outside this module (e.g. EV, Glib,
805	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1403	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
806	to call C<poll_cb> to check the results.	1404	you have to call C<poll_cb> to check the results.
807		1405
808	See C<poll_cb> for an example.	1406	See C<poll_cb> for an example.
809		1407
810	=item IO::AIO::poll_cb	1408	=item IO::AIO::poll_cb
811		1409
812	Process all outstanding events on the result pipe. You have to call this	1410	Process some outstanding events on the result pipe. You have to call this
813	regularly. Returns the number of events processed. Returns immediately	1411	regularly. Returns C<0> if all events could be processed, or C<-1> if it
814	when no events are outstanding.	1412	returned earlier for whatever reason. Returns immediately when no events
		1413	are outstanding. The amount of events processed depends on the settings of
		1414	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
815		1415
816	If not all requests were processed for whatever reason, the filehandle	1416	If not all requests were processed for whatever reason, the filehandle
817	will still be ready when C<poll_cb> returns.	1417	will still be ready when C<poll_cb> returns, so normally you don't have to
		1418	do anything special to have it called later.
818		1419
819	Example: Install an Event watcher that automatically calls	1420	Example: Install an Event watcher that automatically calls
820	IO::AIO::poll_cb with high priority:	1421	IO::AIO::poll_cb with high priority (more examples can be found in the
		1422	SYNOPSIS section, at the top of this document):
821		1423
822	Event->io (fd => IO::AIO::poll_fileno,	1424	Event->io (fd => IO::AIO::poll_fileno,
823	poll => 'r', async => 1,	1425	poll => 'r', async => 1,
824	cb => \&IO::AIO::poll_cb);	1426	cb => \&IO::AIO::poll_cb);
825		1427
826	=item IO::AIO::poll_some $max_requests	1428	=item IO::AIO::poll_wait
827		1429
828	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests	1430	If there are any outstanding requests and none of them in the result
829	at a time.	1431	phase, wait till the result filehandle becomes ready for reading (simply
		1432	does a C<select> on the filehandle. This is useful if you want to
		1433	synchronously wait for some requests to finish).
830		1434
831	Useful if you want to ensure some level of interactiveness when perl is	1435	See C<nreqs> for an example.
832	not fast enough to process all requests in time.	1436
		1437	=item IO::AIO::poll
		1438
		1439	Waits until some requests have been handled.
		1440
		1441	Returns the number of requests processed, but is otherwise strictly
		1442	equivalent to:
		1443
		1444	IO::AIO::poll_wait, IO::AIO::poll_cb
		1445
		1446	=item IO::AIO::flush
		1447
		1448	Wait till all outstanding AIO requests have been handled.
		1449
		1450	Strictly equivalent to:
		1451
		1452	IO::AIO::poll_wait, IO::AIO::poll_cb
		1453	while IO::AIO::nreqs;
		1454
		1455	=item IO::AIO::max_poll_reqs $nreqs
		1456
		1457	=item IO::AIO::max_poll_time $seconds
		1458
		1459	These set the maximum number of requests (default C<0>, meaning infinity)
		1460	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1461	the maximum amount of time (default C<0>, meaning infinity) spent in
		1462	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1463	of time C<poll_cb> is allowed to use).
		1464
		1465	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1466	syscall per request processed, which is not normally a problem unless your
		1467	callbacks are really really fast or your OS is really really slow (I am
		1468	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1469
		1470	Setting these is useful if you want to ensure some level of
		1471	interactiveness when perl is not fast enough to process all requests in
		1472	time.
		1473
		1474	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
833		1475
834	Example: Install an Event watcher that automatically calls	1476	Example: Install an Event watcher that automatically calls
835	IO::AIO::poll_some with low priority, to ensure that other parts of the	1477	IO::AIO::poll_cb with low priority, to ensure that other parts of the
836	program get the CPU sometimes even under high AIO load.	1478	program get the CPU sometimes even under high AIO load.
837		1479
		1480	# try not to spend much more than 0.1s in poll_cb
		1481	IO::AIO::max_poll_time 0.1;
		1482
		1483	# use a low priority so other tasks have priority
838	Event->io (fd => IO::AIO::poll_fileno,	1484	Event->io (fd => IO::AIO::poll_fileno,
839	poll => 'r', nice => 1,	1485	poll => 'r', nice => 1,
840	cb => sub { IO::AIO::poll_some 256 });	1486	cb => &IO::AIO::poll_cb);
841		1487
842	=item IO::AIO::poll_wait	1488	=back
843		1489
844	Wait till the result filehandle becomes ready for reading (simply does a	1490	=head3 CONTROLLING THE NUMBER OF THREADS
845	C<select> on the filehandle. This is useful if you want to synchronously wait
846	for some requests to finish).
847		1491
848	See C<nreqs> for an example.	1492	=over
849
850	=item IO::AIO::nreqs
851
852	Returns the number of requests currently in the ready, execute or pending
853	states (i.e. for which their callback has not been invoked yet).
854
855	Example: wait till there are no outstanding requests anymore:
856
857	IO::AIO::poll_wait, IO::AIO::poll_cb
858	while IO::AIO::nreqs;
859
860	=item IO::AIO::nready
861
862	Returns the number of requests currently in the ready state (not yet
863	executed).
864
865	=item IO::AIO::npending
866
867	Returns the number of requests currently in the pending state (executed,
868	but not yet processed by poll_cb).
869
870	=item IO::AIO::flush
871
872	Wait till all outstanding AIO requests have been handled.
873
874	Strictly equivalent to:
875
876	IO::AIO::poll_wait, IO::AIO::poll_cb
877	while IO::AIO::nreqs;
878
879	=item IO::AIO::poll
880
881	Waits until some requests have been handled.
882
883	Strictly equivalent to:
884
885	IO::AIO::poll_wait, IO::AIO::poll_cb
886	if IO::AIO::nreqs;
887		1493
888	=item IO::AIO::min_parallel $nthreads	1494	=item IO::AIO::min_parallel $nthreads
889		1495
890	Set the minimum number of AIO threads to C<$nthreads>. The current	1496	Set the minimum number of AIO threads to C<$nthreads>. The current
891	default is C<8>, which means eight asynchronous operations can execute	1497	default is C<8>, which means eight asynchronous operations can execute
892	concurrently at any one time (the number of outstanding requests,	1498	concurrently at any one time (the number of outstanding requests,
893	however, is unlimited).	1499	however, is unlimited).
894		1500
895	IO::AIO starts threads only on demand, when an AIO request is queued and	1501	IO::AIO starts threads only on demand, when an AIO request is queued and
896	no free thread exists.	1502	no free thread exists. Please note that queueing up a hundred requests can
		1503	create demand for a hundred threads, even if it turns out that everything
		1504	is in the cache and could have been processed faster by a single thread.
897		1505
898	It is recommended to keep the number of threads relatively low, as some	1506	It is recommended to keep the number of threads relatively low, as some
899	Linux kernel versions will scale negatively with the number of threads	1507	Linux kernel versions will scale negatively with the number of threads
900	(higher parallelity => MUCH higher latency). With current Linux 2.6	1508	(higher parallelity => MUCH higher latency). With current Linux 2.6
901	versions, 4-32 threads should be fine.	1509	versions, 4-32 threads should be fine.
…		…
915	This module automatically runs C<max_parallel 0> at program end, to ensure	1523	This module automatically runs C<max_parallel 0> at program end, to ensure
916	that all threads are killed and that there are no outstanding requests.	1524	that all threads are killed and that there are no outstanding requests.
917		1525
918	Under normal circumstances you don't need to call this function.	1526	Under normal circumstances you don't need to call this function.
919		1527
		1528	=item IO::AIO::max_idle $nthreads
		1529
		1530	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1531	threads that did not get a request to process within 10 seconds). That
		1532	means if a thread becomes idle while C<$nthreads> other threads are also
		1533	idle, it will free its resources and exit.
		1534
		1535	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1536	to allow for extremely high load situations, but want to free resources
		1537	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1538
		1539	The default is probably ok in most situations, especially if thread
		1540	creation is fast. If thread creation is very slow on your system you might
		1541	want to use larger values.
		1542
920	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1543	=item IO::AIO::max_outstanding $maxreqs
921		1544
922	This is a very bad function to use in interactive programs because it	1545	This is a very bad function to use in interactive programs because it
923	blocks, and a bad way to reduce concurrency because it is inexact: Better	1546	blocks, and a bad way to reduce concurrency because it is inexact: Better
924	use an C<aio_group> together with a feed callback.	1547	use an C<aio_group> together with a feed callback.
925		1548
926	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1549	Sets the maximum number of outstanding requests to C<$nreqs>. If you
927	to queue up more than this number of requests, the next call to the	1550	do queue up more than this number of requests, the next call to the
928	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)	1551	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
929	function will block until the limit is no longer exceeded.	1552	function will block until the limit is no longer exceeded.
930		1553
931	The default value is very large, so there is no practical limit on the	1554	The default value is very large, so there is no practical limit on the
932	number of outstanding requests.	1555	number of outstanding requests.
933		1556
934	You can still queue as many requests as you want. Therefore,	1557	You can still queue as many requests as you want. Therefore,
935	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	1558	C<max_outstanding> is mainly useful in simple scripts (with low values) or
936	as a stop gap to shield against fatal memory overflow (with large values).	1559	as a stop gap to shield against fatal memory overflow (with large values).
937		1560
938	=back	1561	=back
939		1562
		1563	=head3 STATISTICAL INFORMATION
		1564
		1565	=over
		1566
		1567	=item IO::AIO::nreqs
		1568
		1569	Returns the number of requests currently in the ready, execute or pending
		1570	states (i.e. for which their callback has not been invoked yet).
		1571
		1572	Example: wait till there are no outstanding requests anymore:
		1573
		1574	IO::AIO::poll_wait, IO::AIO::poll_cb
		1575	while IO::AIO::nreqs;
		1576
		1577	=item IO::AIO::nready
		1578
		1579	Returns the number of requests currently in the ready state (not yet
		1580	executed).
		1581
		1582	=item IO::AIO::npending
		1583
		1584	Returns the number of requests currently in the pending state (executed,
		1585	but not yet processed by poll_cb).
		1586
		1587	=back
		1588
		1589	=head3 MISCELLANEOUS FUNCTIONS
		1590
		1591	IO::AIO implements some functions that might be useful, but are not
		1592	asynchronous.
		1593
		1594	=over 4
		1595
		1596	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1597
		1598	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1599	but is blocking (this makes most sense if you know the input data is
		1600	likely cached already and the output filehandle is set to non-blocking
		1601	operations).
		1602
		1603	Returns the number of bytes copied, or C<-1> on error.
		1604
		1605	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1606
		1607	Simply calls the C<posix_fadvise> function (see its
		1608	manpage for details). The following advice constants are
		1609	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1610	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1611	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1612
		1613	On systems that do not implement C<posix_fadvise>, this function returns
		1614	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1615
		1616	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1617
		1618	Simply calls the C<posix_madvise> function (see its
		1619	manpage for details). The following advice constants are
		1620	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1621	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1622
		1623	On systems that do not implement C<posix_madvise>, this function returns
		1624	ENOSYS, otherwise the return value of C<posix_madvise>.
		1625
		1626	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1627
		1628	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1629	$scalar (see its manpage for details). The following protect
		1630	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1631	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1632
		1633	On systems that do not implement C<mprotect>, this function returns
		1634	ENOSYS, otherwise the return value of C<mprotect>.
		1635
		1636	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1637
		1638	Memory-maps a file (or anonymous memory range) and attaches it to the
		1639	given C<$scalar>, which will act like a string scalar.
		1640
		1641	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1642	change the string length, and most read-only operations such as copying it
		1643	or searching it with regexes and so on.
		1644
		1645	Anything else is unsafe and will, at best, result in memory leaks.
		1646
		1647	The memory map associated with the C<$scalar> is automatically removed
		1648	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1649	C<IO::AIO::munmap> functions are called.
		1650
		1651	This calls the C<mmap>(2) function internally. See your system's manual
		1652	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1653
		1654	The C<$length> must be larger than zero and smaller than the actual
		1655	filesize.
		1656
		1657	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1658	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1659
		1660	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1661	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1662	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1663	(which is set to C<MAP_ANON> if your system only provides this
		1664	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1665	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1666	C<IO::AIO::MAP_NONBLOCK>
		1667
		1668	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1669
		1670	C<$offset> is the offset from the start of the file - it generally must be
		1671	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1672
		1673	Example:
		1674
		1675	use Digest::MD5;
		1676	use IO::AIO;
		1677
		1678	open my $fh, "<verybigfile"
		1679	or die "$!";
		1680
		1681	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1682	or die "verybigfile: $!";
		1683
		1684	my $fast_md5 = md5 $data;
		1685
		1686	=item IO::AIO::munmap $scalar
		1687
		1688	Removes a previous mmap and undefines the C<$scalar>.
		1689
		1690	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1691
		1692	Calls the C<munlock> function, undoing the effects of a previous
		1693	C<aio_mlock> call (see its description for details).
		1694
		1695	=item IO::AIO::munlockall
		1696
		1697	Calls the C<munlockall> function.
		1698
		1699	On systems that do not implement C<munlockall>, this function returns
		1700	ENOSYS, otherwise the return value of C<munlockall>.
		1701
		1702	=back
		1703
940	=cut	1704	=cut
941		1705
942	# support function to convert a fd into a perl filehandle
943	sub _fd2fh {
944	return undef if $_[0] < 0;
945
946	# try to generate nice filehandles
947	my $sym = "IO::AIO::fd#$_[0]";
948	local *$sym;
949
950	open *$sym, "+<&=$_[0]" # usually works under any unix
951	or open *$sym, "<&=$_[0]" # cygwin needs this
952	or open *$sym, ">&=$_[0]" # or this
953	or return undef;
954
955	*$sym
956	}
957
958	min_parallel 8;	1706	min_parallel 8;
959		1707
		1708	END { flush }
		1709
960	1;	1710	1;
		1711
		1712	=head1 EVENT LOOP INTEGRATION
		1713
		1714	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1715	automatically into many event loops:
		1716
		1717	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1718	use AnyEvent::AIO;
		1719
		1720	You can also integrate IO::AIO manually into many event loops, here are
		1721	some examples of how to do this:
		1722
		1723	# EV integration
		1724	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1725
		1726	# Event integration
		1727	Event->io (fd => IO::AIO::poll_fileno,
		1728	poll => 'r',
		1729	cb => \&IO::AIO::poll_cb);
		1730
		1731	# Glib/Gtk2 integration
		1732	add_watch Glib::IO IO::AIO::poll_fileno,
		1733	in => sub { IO::AIO::poll_cb; 1 };
		1734
		1735	# Tk integration
		1736	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1737	readable => \&IO::AIO::poll_cb);
		1738
		1739	# Danga::Socket integration
		1740	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1741	\&IO::AIO::poll_cb);
961		1742
962	=head2 FORK BEHAVIOUR	1743	=head2 FORK BEHAVIOUR
963		1744
964	This module should do "the right thing" when the process using it forks:	1745	This module should do "the right thing" when the process using it forks:
965		1746
…		…
983	bytes of memory. In addition, stat requests need a stat buffer (possibly	1764	bytes of memory. In addition, stat requests need a stat buffer (possibly
984	a few hundred bytes), readdir requires a result buffer and so on. Perl	1765	a few hundred bytes), readdir requires a result buffer and so on. Perl
985	scalars and other data passed into aio requests will also be locked and	1766	scalars and other data passed into aio requests will also be locked and
986	will consume memory till the request has entered the done state.	1767	will consume memory till the request has entered the done state.
987		1768
988	This is now awfully much, so queuing lots of requests is not usually a	1769	This is not awfully much, so queuing lots of requests is not usually a
989	problem.	1770	problem.
990		1771
991	Per-thread usage:	1772	Per-thread usage:
992		1773
993	In the execution phase, some aio requests require more memory for	1774	In the execution phase, some aio requests require more memory for
…		…
998		1779
999	Known bugs will be fixed in the next release.	1780	Known bugs will be fixed in the next release.
1000		1781
1001	=head1 SEE ALSO	1782	=head1 SEE ALSO
1002		1783
1003	L<Coro::AIO>.	1784	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1785	more natural syntax.
1004		1786
1005	=head1 AUTHOR	1787	=head1 AUTHOR
1006		1788
1007	Marc Lehmann <schmorp@schmorp.de>	1789	Marc Lehmann <schmorp@schmorp.de>
1008	http://home.schmorp.de/	1790	http://home.schmorp.de/

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