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Revision 1.74 by root, Tue Oct 24 17:22:17 2006 UTC vs.
Revision 1.171 by root, Sat Jan 2 14:24:32 2010 UTC

…		…
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", 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
		31	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		32	use AnyEvent::AIO;
		33
30	# AnyEvent integration	34	# EV integration
31	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	35	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
32	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
33		36
34	# Event integration	37	# Event integration
35	Event->io (fd => IO::AIO::poll_fileno,	38	Event->io (fd => IO::AIO::poll_fileno,
36	poll => 'r',	39	poll => 'r',
37	cb => \&IO::AIO::poll_cb);	40	cb => \&IO::AIO::poll_cb);
…		…
49	\&IO::AIO::poll_cb);	52	\&IO::AIO::poll_cb);
50		53
51	=head1 DESCRIPTION	54	=head1 DESCRIPTION
52		55
53	This module implements asynchronous I/O using whatever means your	56	This module implements asynchronous I/O using whatever means your
54	operating system supports.	57	operating system supports. It is implemented as an interface to C<libeio>
		58	(L<http://software.schmorp.de/pkg/libeio.html>).
		59
		60	Asynchronous means that operations that can normally block your program
		61	(e.g. reading from disk) will be done asynchronously: the operation
		62	will still block, but you can do something else in the meantime. This
		63	is extremely useful for programs that need to stay interactive even
		64	when doing heavy I/O (GUI programs, high performance network servers
		65	etc.), but can also be used to easily do operations in parallel that are
		66	normally done sequentially, e.g. stat'ing many files, which is much faster
		67	on a RAID volume or over NFS when you do a number of stat operations
		68	concurrently.
		69
		70	While most of this works on all types of file descriptors (for
		71	example sockets), using these functions on file descriptors that
		72	support nonblocking operation (again, sockets, pipes etc.) is
		73	very inefficient. Use an event loop for that (such as the L<EV>
		74	module): IO::AIO will naturally fit into such an event loop itself.
55		75
56	In this version, a number of threads are started that execute your	76	In this version, a number of threads are started that execute your
57	requests and signal their completion. You don't need thread support	77	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	78	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	79	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	80	functions available on many operating systems. However, they are often
61	not well-supported or restricted (Linux doesn't allow them on normal	81	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	82	files currently, for example), and they would only support aio_read and
63	aio_write, so the remaining functionality would have to be implemented	83	aio_write, so the remaining functionality would have to be implemented
64	using threads anyway.	84	using threads anyway.
65		85
66	Although the module will work with in the presence of other (Perl-)	86	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	87	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	88	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.	89	call C<poll_cb> (or other C<aio_> functions) recursively.
		90
		91	=head2 EXAMPLE
		92
		93	This is a simple example that uses the EV module and loads
		94	F</etc/passwd> asynchronously:
		95
		96	use Fcntl;
		97	use EV;
		98	use IO::AIO;
		99
		100	# register the IO::AIO callback with EV
		101	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		102
		103	# queue the request to open /etc/passwd
		104	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		105	my $fh = shift
		106	or die "error while opening: $!";
		107
		108	# stat'ing filehandles is generally non-blocking
		109	my $size = -s $fh;
		110
		111	# queue a request to read the file
		112	my $contents;
		113	aio_read $fh, 0, $size, $contents, 0, sub {
		114	$_[0] == $size
		115	or die "short read: $!";
		116
		117	close $fh;
		118
		119	# file contents now in $contents
		120	print $contents;
		121
		122	# exit event loop and program
		123	EV::unloop;
		124	};
		125	};
		126
		127	# possibly queue up other requests, or open GUI windows,
		128	# check for sockets etc. etc.
		129
		130	# process events as long as there are some:
		131	EV::loop;
70		132
71	=head1 REQUEST ANATOMY AND LIFETIME	133	=head1 REQUEST ANATOMY AND LIFETIME
72		134
73	Every C<aio_*> function creates a request. which is a C data structure not	135	Every C<aio_*> function creates a request. which is a C data structure not
74	directly visible to Perl.	136	directly visible to Perl.
…		…
116	Request has reached the end of its lifetime and holds no resources anymore	178	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	179	(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	180	aio request is severed and calling its methods will either do nothing or
119	result in a runtime error).	181	result in a runtime error).
120		182
		183	=back
		184
121	=cut	185	=cut
122		186
123	package IO::AIO;	187	package IO::AIO;
124		188
125	no warnings;	189	use Carp ();
126	use strict 'vars';	190
		191	use common::sense;
127		192
128	use base 'Exporter';	193	use base 'Exporter';
129		194
130	BEGIN {	195	BEGIN {
131	our $VERSION = '2.0';	196	our $VERSION = '3.4';
132		197
133	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	198	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	199	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	200	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
		201	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
		202	aio_rename aio_link aio_move aio_copy aio_group
		203	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		204	aio_chmod aio_utime aio_truncate
136	aio_group aio_nop);	205	aio_msync aio_mtouch);
		206
137	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	207	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
138	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	208	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139	min_parallel max_parallel max_outstanding nreqs);	209	min_parallel max_parallel max_idle
		210	nreqs nready npending nthreads
		211	max_poll_time max_poll_reqs
		212	sendfile fadvise);
		213
		214	push @AIO_REQ, qw(aio_busy); # not exported
140		215
141	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	216	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142		217
143	require XSLoader;	218	require XSLoader;
144	XSLoader::load ("IO::AIO", $VERSION);	219	XSLoader::load ("IO::AIO", $VERSION);
145	}	220	}
146		221
147	=head1 FUNCTIONS	222	=head1 FUNCTIONS
148		223
149	=head2 AIO FUNCTIONS	224	=head2 AIO REQUEST FUNCTIONS
150		225
151	All the C<aio_*> calls are more or less thin wrappers around the syscall	226	All the C<aio_*> calls are more or less thin wrappers around the syscall
152	with the same name (sans C<aio_>). The arguments are similar or identical,	227	with the same name (sans C<aio_>). The arguments are similar or identical,
153	and they all accept an additional (and optional) C<$callback> argument	228	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	229	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	230	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	231	perl, which usually delivers "false") as its sole argument after the given
157	syscall has been executed asynchronously.	232	syscall has been executed asynchronously.
158		233
159	All functions expecting a filehandle keep a copy of the filehandle	234	All functions expecting a filehandle keep a copy of the filehandle
160	internally until the request has finished.	235	internally until the request has finished.
161		236
162	All requests return objects of type L<IO::AIO::REQ> that allow further	237	All functions return request objects of type L<IO::AIO::REQ> that allow
163	manipulation of those requests while they are in-flight.	238	further manipulation of those requests while they are in-flight.
164		239
165	The pathnames you pass to these routines I<must> be absolute and	240	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	241	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	242	request is being executed, the current working directory could have
168	changed. Alternatively, you can make sure that you never change the	243	changed. Alternatively, you can make sure that you never change the
169	current working directory.	244	current working directory anywhere in the program and then use relative
		245	paths.
170		246
171	To encode pathnames to byte form, either make sure you either: a)	247	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	248	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	249	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	250	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)	251	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176	use something else.	252	use something else to ensure your scalar has the correct contents.
		253
		254	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		255	handles correctly whether it is set or not.
177		256
178	=over 4	257	=over 4
179		258
180	=item aioreq_pri $pri	259	=item $prev_pri = aioreq_pri [$pri]
181		260
182	Sets the priority for the next aio request. The default priority	261	Returns the priority value that would be used for the next request and, if
		262	C<$pri> is given, sets the priority for the next aio request.
		263
183	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	264	The default priority is C<0>, the minimum and maximum priorities are C<-4>
184	respectively. Requests with higher priority will be serviced first.	265	and C<4>, respectively. Requests with higher priority will be serviced
		266	first.
185		267
186	The priority will be reset to C<0> after each call to one of the C<aio_>	268	The priority will be reset to C<0> after each call to one of the C<aio_*>
187	functions.	269	functions.
188		270
189	Example: open a file with low priority, then read something from it with	271	Example: open a file with low priority, then read something from it with
190	higher priority so the read request is serviced before other low priority	272	higher priority so the read request is serviced before other low priority
191	open requests (potentially spamming the cache):	273	open requests (potentially spamming the cache):
…		…
198	aio_read $_[0], ..., sub {	280	aio_read $_[0], ..., sub {
199	...	281	...
200	};	282	};
201	};	283	};
202		284
		285
203	=item aioreq_nice $pri_adjust	286	=item aioreq_nice $pri_adjust
204		287
205	Similar to C<aioreq_pri>, but subtracts the given value from the current	288	Similar to C<aioreq_pri>, but subtracts the given value from the current
206	priority, so effects are cumulative.	289	priority, so the effect is cumulative.
		290
207		291
208	=item aio_open $pathname, $flags, $mode, $callback->($fh)	292	=item aio_open $pathname, $flags, $mode, $callback->($fh)
209		293
210	Asynchronously open or create a file and call the callback with a newly	294	Asynchronously open or create a file and call the callback with a newly
211	created filehandle for the file.	295	created filehandle for the file.
…		…
217	list. They are the same as used by C<sysopen>.	301	list. They are the same as used by C<sysopen>.
218		302
219	Likewise, C<$mode> specifies the mode of the newly created file, if it	303	Likewise, C<$mode> specifies the mode of the newly created file, if it
220	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	304	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
221	except that it is mandatory (i.e. use C<0> if you don't create new files,	305	except that it is mandatory (i.e. use C<0> if you don't create new files,
222	and C<0666> or C<0777> if you do).	306	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		307	by the umask in effect then the request is being executed, so better never
		308	change the umask.
223		309
224	Example:	310	Example:
225		311
226	aio_open "/etc/passwd", O_RDONLY, 0, sub {	312	aio_open "/etc/passwd", O_RDONLY, 0, sub {
227	if ($_[0]) {	313	if ($_[0]) {
…		…
230	} else {	316	} else {
231	die "open failed: $!\n";	317	die "open failed: $!\n";
232	}	318	}
233	};	319	};
234		320
		321
235	=item aio_close $fh, $callback->($status)	322	=item aio_close $fh, $callback->($status)
236		323
237	Asynchronously close a file and call the callback with the result	324	Asynchronously close a file and call the callback with the result
238	code. I<WARNING:> although accepted, you should not pass in a perl	325	code.
239	filehandle here, as perl will likely close the file descriptor another
240	time when the filehandle is destroyed. Normally, you can safely call perls
241	C<close> or just let filehandles go out of scope.
242		326
243	This is supposed to be a bug in the API, so that might change. It's	327	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
244	therefore best to avoid this function.	328	closing the file descriptor associated with the filehandle itself.
		329
		330	Therefore, C<aio_close> will not close the filehandle - instead it will
		331	use dup2 to overwrite the file descriptor with the write-end of a pipe
		332	(the pipe fd will be created on demand and will be cached).
		333
		334	Or in other words: the file descriptor will be closed, but it will not be
		335	free for reuse until the perl filehandle is closed.
		336
		337	=cut
245		338
246	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	339	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
247		340
248	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	341	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
249		342
250	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	343	Reads or writes C<$length> bytes from or to the specified C<$fh> and
251	into the scalar given by C<data> and offset C<dataoffset> and calls the	344	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
252	callback without the actual number of bytes read (or -1 on error, just	345	and calls the callback without the actual number of bytes read (or -1 on
253	like the syscall).	346	error, just like the syscall).
		347
		348	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		349	offset plus the actual number of bytes read.
		350
		351	If C<$offset> is undefined, then the current file descriptor offset will
		352	be used (and updated), otherwise the file descriptor offset will not be
		353	changed by these calls.
		354
		355	If C<$length> is undefined in C<aio_write>, use the remaining length of
		356	C<$data>.
		357
		358	If C<$dataoffset> is less than zero, it will be counted from the end of
		359	C<$data>.
254		360
255	The C<$data> scalar I<MUST NOT> be modified in any way while the request	361	The C<$data> scalar I<MUST NOT> be modified in any way while the request
256	is outstanding. Modifying it can result in segfaults or WW3 (if the	362	is outstanding. Modifying it can result in segfaults or World War III (if
257	necessary/optional hardware is installed).	363	the necessary/optional hardware is installed).
258		364
259	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	365	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
260	offset C<0> within the scalar:	366	offset C<0> within the scalar:
261		367
262	aio_read $fh, 7, 15, $buffer, 0, sub {	368	aio_read $fh, 7, 15, $buffer, 0, sub {
263	$_[0] > 0 or die "read error: $!";	369	$_[0] > 0 or die "read error: $!";
264	print "read $_[0] bytes: <$buffer>\n";	370	print "read $_[0] bytes: <$buffer>\n";
265	};	371	};
266		372
267	=item aio_move $srcpath, $dstpath, $callback->($status)
268
269	Try to move the I<file> (directories not supported as either source or
270	destination) from C<$srcpath> to C<$dstpath> and call the callback with
271	the C<0> (error) or C<-1> ok.
272
273	This is a composite request that tries to rename(2) the file first. If
274	rename files with C<EXDEV>, it creates the destination file with mode 0200
275	and copies the contents of the source file into it using C<aio_sendfile>,
276	followed by restoring atime, mtime, access mode and uid/gid, in that
277	order, and unlinking the C<$srcpath>.
278
279	If an error occurs, the partial destination file will be unlinked, if
280	possible, except when setting atime, mtime, access mode and uid/gid, where
281	errors are being ignored.
282
283	=cut
284
285	sub aio_move($$$) {
286	my ($src, $dst, $cb) = @_;
287
288	my $grp = aio_group $cb;
289
290	add $grp aio_rename $src, $dst, sub {
291	if ($_[0] && $! == EXDEV) {
292	add $grp aio_open $src, O_RDONLY, 0, sub {
293	if (my $src_fh = $_[0]) {
294	my @stat = stat $src_fh;
295
296	add $grp aio_open $dst, O_WRONLY, 0200, sub {
297	if (my $dst_fh = $_[0]) {
298	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
299	close $src_fh;
300
301	if ($_[0] == $stat[7]) {
302	utime $stat[8], $stat[9], $dst;
303	chmod $stat[2] & 07777, $dst_fh;
304	chown $stat[4], $stat[5], $dst_fh;
305	close $dst_fh;
306
307	add $grp aio_unlink $src, sub {
308	$grp->result ($_[0]);
309	};
310	} else {
311	my $errno = $!;
312	add $grp aio_unlink $dst, sub {
313	$! = $errno;
314	$grp->result (-1);
315	};
316	}
317	};
318	} else {
319	$grp->result (-1);
320	}
321	},
322
323	} else {
324	$grp->result (-1);
325	}
326	};
327	} else {
328	$grp->result ($_[0]);
329	}
330	};
331
332	$grp
333	}
334		373
335	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	374	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
336		375
337	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	376	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
338	reading at byte offset C<$in_offset>, and starts writing at the current	377	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
342		381
343	This call tries to make use of a native C<sendfile> syscall to provide	382	This call tries to make use of a native C<sendfile> syscall to provide
344	zero-copy operation. For this to work, C<$out_fh> should refer to a	383	zero-copy operation. For this to work, C<$out_fh> should refer to a
345	socket, and C<$in_fh> should refer to mmap'able file.	384	socket, and C<$in_fh> should refer to mmap'able file.
346		385
347	If the native sendfile call fails or is not implemented, it will be	386	If a native sendfile cannot be found or it fails with C<ENOSYS>,
		387	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,
348	emulated, so you can call C<aio_sendfile> on any type of filehandle	388	it will be emulated, so you can call C<aio_sendfile> on any type of
349	regardless of the limitations of the operating system.	389	filehandle regardless of the limitations of the operating system.
350		390
351	Please note, however, that C<aio_sendfile> can read more bytes from	391	Please note, however, that C<aio_sendfile> can read more bytes from
352	C<$in_fh> than are written, and there is no way to find out how many	392	C<$in_fh> than are written, and there is no way to find out how many
353	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	393	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
354	provides the number of bytes written to C<$out_fh>. Only if the result	394	provides the number of bytes written to C<$out_fh>. Only if the result
355	value equals C<$length> one can assume that C<$length> bytes have been	395	value equals C<$length> one can assume that C<$length> bytes have been
356	read.	396	read.
		397
357		398
358	=item aio_readahead $fh,$offset,$length, $callback->($retval)	399	=item aio_readahead $fh,$offset,$length, $callback->($retval)
359		400
360	C<aio_readahead> populates the page cache with data from a file so that	401	C<aio_readahead> populates the page cache with data from a file so that
361	subsequent reads from that file will not block on disk I/O. The C<$offset>	402	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
367	file. The current file offset of the file is left unchanged.	408	file. The current file offset of the file is left unchanged.
368		409
369	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	410	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
370	emulated by simply reading the data, which would have a similar effect.	411	emulated by simply reading the data, which would have a similar effect.
371		412
		413
372	=item aio_stat $fh_or_path, $callback->($status)	414	=item aio_stat $fh_or_path, $callback->($status)
373		415
374	=item aio_lstat $fh, $callback->($status)	416	=item aio_lstat $fh, $callback->($status)
375		417
376	Works like perl's C<stat> or C<lstat> in void context. The callback will	418	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
389	aio_stat "/etc/passwd", sub {	431	aio_stat "/etc/passwd", sub {
390	$_[0] and die "stat failed: $!";	432	$_[0] and die "stat failed: $!";
391	print "size is ", -s _, "\n";	433	print "size is ", -s _, "\n";
392	};	434	};
393		435
		436
		437	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		438
		439	Works like perl's C<utime> function (including the special case of $atime
		440	and $mtime being undef). Fractional times are supported if the underlying
		441	syscalls support them.
		442
		443	When called with a pathname, uses utimes(2) if available, otherwise
		444	utime(2). If called on a file descriptor, uses futimes(2) if available,
		445	otherwise returns ENOSYS, so this is not portable.
		446
		447	Examples:
		448
		449	# set atime and mtime to current time (basically touch(1)):
		450	aio_utime "path", undef, undef;
		451	# set atime to current time and mtime to beginning of the epoch:
		452	aio_utime "path", time, undef; # undef==0
		453
		454
		455	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		456
		457	Works like perl's C<chown> function, except that C<undef> for either $uid
		458	or $gid is being interpreted as "do not change" (but -1 can also be used).
		459
		460	Examples:
		461
		462	# same as "chown root path" in the shell:
		463	aio_chown "path", 0, -1;
		464	# same as above:
		465	aio_chown "path", 0, undef;
		466
		467
		468	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		469
		470	Works like truncate(2) or ftruncate(2).
		471
		472
		473	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		474
		475	Works like perl's C<chmod> function.
		476
		477
394	=item aio_unlink $pathname, $callback->($status)	478	=item aio_unlink $pathname, $callback->($status)
395		479
396	Asynchronously unlink (delete) a file and call the callback with the	480	Asynchronously unlink (delete) a file and call the callback with the
397	result code.	481	result code.
398		482
		483
		484	=item aio_mknod $path, $mode, $dev, $callback->($status)
		485
		486	[EXPERIMENTAL]
		487
		488	Asynchronously create a device node (or fifo). See mknod(2).
		489
		490	The only (POSIX-) portable way of calling this function is:
		491
		492	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		493
		494
399	=item aio_link $srcpath, $dstpath, $callback->($status)	495	=item aio_link $srcpath, $dstpath, $callback->($status)
400		496
401	Asynchronously create a new link to the existing object at C<$srcpath> at	497	Asynchronously create a new link to the existing object at C<$srcpath> at
402	the path C<$dstpath> and call the callback with the result code.	498	the path C<$dstpath> and call the callback with the result code.
403		499
		500
404	=item aio_symlink $srcpath, $dstpath, $callback->($status)	501	=item aio_symlink $srcpath, $dstpath, $callback->($status)
405		502
406	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	503	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
407	the path C<$dstpath> and call the callback with the result code.	504	the path C<$dstpath> and call the callback with the result code.
408		505
		506
		507	=item aio_readlink $path, $callback->($link)
		508
		509	Asynchronously read the symlink specified by C<$path> and pass it to
		510	the callback. If an error occurs, nothing or undef gets passed to the
		511	callback.
		512
		513
409	=item aio_rename $srcpath, $dstpath, $callback->($status)	514	=item aio_rename $srcpath, $dstpath, $callback->($status)
410		515
411	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	516	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
412	rename(2) and call the callback with the result code.	517	rename(2) and call the callback with the result code.
413		518
		519
		520	=item aio_mkdir $pathname, $mode, $callback->($status)
		521
		522	Asynchronously mkdir (create) a directory and call the callback with
		523	the result code. C<$mode> will be modified by the umask at the time the
		524	request is executed, so do not change your umask.
		525
		526
414	=item aio_rmdir $pathname, $callback->($status)	527	=item aio_rmdir $pathname, $callback->($status)
415		528
416	Asynchronously rmdir (delete) a directory and call the callback with the	529	Asynchronously rmdir (delete) a directory and call the callback with the
417	result code.	530	result code.
		531
418		532
419	=item aio_readdir $pathname, $callback->($entries)	533	=item aio_readdir $pathname, $callback->($entries)
420		534
421	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	535	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
422	directory (i.e. opendir + readdir + closedir). The entries will not be	536	directory (i.e. opendir + readdir + closedir). The entries will not be
423	sorted, and will B<NOT> include the C<.> and C<..> entries.	537	sorted, and will B<NOT> include the C<.> and C<..> entries.
424		538
425	The callback a single argument which is either C<undef> or an array-ref	539	The callback is passed a single argument which is either C<undef> or an
426	with the filenames.	540	array-ref with the filenames.
		541
		542
		543	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		544
		545	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		546	behaviour and output format. In case of an error, C<$entries> will be
		547	C<undef>.
		548
		549	The flags are a combination of the following constants, ORed together (the
		550	flags will also be passed to the callback, possibly modified):
		551
		552	=over 4
		553
		554	=item IO::AIO::READDIR_DENTS
		555
		556	When this flag is off, then the callback gets an arrayref with of names
		557	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		558	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		559	entry in more detail.
		560
		561	C<$name> is the name of the entry.
		562
		563	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		564
		565	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		566	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		567	C<IO::AIO::DT_WHT>.
		568
		569	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		570	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		571	scalars are read-only: you can not modify them.
		572
		573	C<$inode> is the inode number (which might not be exact on systems with 64
		574	bit inode numbers and 32 bit perls). This field has unspecified content on
		575	systems that do not deliver the inode information.
		576
		577	=item IO::AIO::READDIR_DIRS_FIRST
		578
		579	When this flag is set, then the names will be returned in an order where
		580	likely directories come first. This is useful when you need to quickly
		581	find directories, or you want to find all directories while avoiding to
		582	stat() each entry.
		583
		584	If the system returns type information in readdir, then this is used
		585	to find directories directly. Otherwise, likely directories are files
		586	beginning with ".", or otherwise files with no dots, of which files with
		587	short names are tried first.
		588
		589	=item IO::AIO::READDIR_STAT_ORDER
		590
		591	When this flag is set, then the names will be returned in an order
		592	suitable for stat()'ing each one. That is, when you plan to stat()
		593	all files in the given directory, then the returned order will likely
		594	be fastest.
		595
		596	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		597	the likely dirs come first, resulting in a less optimal stat order.
		598
		599	=item IO::AIO::READDIR_FOUND_UNKNOWN
		600
		601	This flag should not be set when calling C<aio_readdirx>. Instead, it
		602	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		603	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		604	C<$type>'s are known, which can be used to speed up some algorithms.
		605
		606	=back
		607
		608
		609	=item aio_load $path, $data, $callback->($status)
		610
		611	This is a composite request that tries to fully load the given file into
		612	memory. Status is the same as with aio_read.
		613
		614	=cut
		615
		616	sub aio_load($$;$) {
		617	my ($path, undef, $cb) = @_;
		618	my $data = \$_[1];
		619
		620	my $pri = aioreq_pri;
		621	my $grp = aio_group $cb;
		622
		623	aioreq_pri $pri;
		624	add $grp aio_open $path, O_RDONLY, 0, sub {
		625	my $fh = shift
		626	or return $grp->result (-1);
		627
		628	aioreq_pri $pri;
		629	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		630	$grp->result ($_[0]);
		631	};
		632	};
		633
		634	$grp
		635	}
		636
		637	=item aio_copy $srcpath, $dstpath, $callback->($status)
		638
		639	Try to copy the I<file> (directories not supported as either source or
		640	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		641	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		642
		643	This is a composite request that creates the destination file with
		644	mode 0200 and copies the contents of the source file into it using
		645	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		646	uid/gid, in that order.
		647
		648	If an error occurs, the partial destination file will be unlinked, if
		649	possible, except when setting atime, mtime, access mode and uid/gid, where
		650	errors are being ignored.
		651
		652	=cut
		653
		654	sub aio_copy($$;$) {
		655	my ($src, $dst, $cb) = @_;
		656
		657	my $pri = aioreq_pri;
		658	my $grp = aio_group $cb;
		659
		660	aioreq_pri $pri;
		661	add $grp aio_open $src, O_RDONLY, 0, sub {
		662	if (my $src_fh = $_[0]) {
		663	my @stat = stat $src_fh; # hmm, might block over nfs?
		664
		665	aioreq_pri $pri;
		666	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		667	if (my $dst_fh = $_[0]) {
		668	aioreq_pri $pri;
		669	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		670	if ($_[0] == $stat[7]) {
		671	$grp->result (0);
		672	close $src_fh;
		673
		674	my $ch = sub {
		675	aioreq_pri $pri;
		676	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		677	aioreq_pri $pri;
		678	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		679	aioreq_pri $pri;
		680	add $grp aio_close $dst_fh;
		681	}
		682	};
		683	};
		684
		685	aioreq_pri $pri;
		686	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		687	if ($_[0] < 0 && $! == ENOSYS) {
		688	aioreq_pri $pri;
		689	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		690	} else {
		691	$ch->();
		692	}
		693	};
		694	} else {
		695	$grp->result (-1);
		696	close $src_fh;
		697	close $dst_fh;
		698
		699	aioreq $pri;
		700	add $grp aio_unlink $dst;
		701	}
		702	};
		703	} else {
		704	$grp->result (-1);
		705	}
		706	},
		707
		708	} else {
		709	$grp->result (-1);
		710	}
		711	};
		712
		713	$grp
		714	}
		715
		716	=item aio_move $srcpath, $dstpath, $callback->($status)
		717
		718	Try to move the I<file> (directories not supported as either source or
		719	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		720	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		721
		722	This is a composite request that tries to rename(2) the file first; if
		723	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		724	that is successful, unlinks the C<$srcpath>.
		725
		726	=cut
		727
		728	sub aio_move($$;$) {
		729	my ($src, $dst, $cb) = @_;
		730
		731	my $pri = aioreq_pri;
		732	my $grp = aio_group $cb;
		733
		734	aioreq_pri $pri;
		735	add $grp aio_rename $src, $dst, sub {
		736	if ($_[0] && $! == EXDEV) {
		737	aioreq_pri $pri;
		738	add $grp aio_copy $src, $dst, sub {
		739	$grp->result ($_[0]);
		740
		741	if (!$_[0]) {
		742	aioreq_pri $pri;
		743	add $grp aio_unlink $src;
		744	}
		745	};
		746	} else {
		747	$grp->result ($_[0]);
		748	}
		749	};
		750
		751	$grp
		752	}
427		753
428	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	754	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
429		755
430	Scans a directory (similar to C<aio_readdir>) but additionally tries to	756	Scans a directory (similar to C<aio_readdir>) but additionally tries to
431	separate the entries of directory C<$path> into two sets of names, ones	757	efficiently separate the entries of directory C<$path> into two sets of
432	you can recurse into (directories or links to them), and ones you cannot	758	names, directories you can recurse into (directories), and ones you cannot
433	recurse into (everything else).	759	recurse into (everything else, including symlinks to directories).
434		760
435	C<aio_scandir> is a composite request that creates of many sub requests_	761	C<aio_scandir> is a composite request that creates of many sub requests_
436	C<$maxreq> specifies the maximum number of outstanding aio requests that	762	C<$maxreq> specifies the maximum number of outstanding aio requests that
437	this function generates. If it is C<< <= 0 >>, then a suitable default	763	this function generates. If it is C<< <= 0 >>, then a suitable default
438	will be chosen (currently 6).	764	will be chosen (currently 4).
439		765
440	On error, the callback is called without arguments, otherwise it receives	766	On error, the callback is called without arguments, otherwise it receives
441	two array-refs with path-relative entry names.	767	two array-refs with path-relative entry names.
442		768
443	Example:	769	Example:
…		…
450		776
451	Implementation notes.	777	Implementation notes.
452		778
453	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	779	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
454		780
		781	If readdir returns file type information, then this is used directly to
		782	find directories.
		783
455	After reading the directory, the modification time, size etc. of the	784	Otherwise, after reading the directory, the modification time, size etc.
456	directory before and after the readdir is checked, and if they match (and	785	of the directory before and after the readdir is checked, and if they
457	isn't the current time), the link count will be used to decide how many	786	match (and isn't the current time), the link count will be used to decide
458	entries are directories (if >= 2). Otherwise, no knowledge of the number	787	how many entries are directories (if >= 2). Otherwise, no knowledge of the
459	of subdirectories will be assumed.	788	number of subdirectories will be assumed.
460		789
461	Then entries will be sorted into likely directories (everything without	790	Then entries will be sorted into likely directories a non-initial dot
462	a non-initial dot currently) and likely non-directories (everything	791	currently) and likely non-directories (see C<aio_readdirx>). Then every
463	else). Then every entry plus an appended C</.> will be C<stat>'ed,	792	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
464	likely directories first. If that succeeds, it assumes that the entry	793	in order of their inode numbers. If that succeeds, it assumes that the
465	is a directory or a symlink to directory (which will be checked	794	entry is a directory or a symlink to directory (which will be checked
466	seperately). This is often faster than stat'ing the entry itself because	795	seperately). This is often faster than stat'ing the entry itself because
467	filesystems might detect the type of the entry without reading the inode	796	filesystems might detect the type of the entry without reading the inode
468	data (e.g. ext2fs filetype feature).	797	data (e.g. ext2fs filetype feature), even on systems that cannot return
		798	the filetype information on readdir.
469		799
470	If the known number of directories (link count - 2) has been reached, the	800	If the known number of directories (link count - 2) has been reached, the
471	rest of the entries is assumed to be non-directories.	801	rest of the entries is assumed to be non-directories.
472		802
473	This only works with certainty on POSIX (= UNIX) filesystems, which	803	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
477	as those tend to return 0 or 1 as link counts, which disables the	807	as those tend to return 0 or 1 as link counts, which disables the
478	directory counting heuristic.	808	directory counting heuristic.
479		809
480	=cut	810	=cut
481		811
482	sub aio_scandir($$$) {	812	sub aio_scandir($$;$) {
483	my ($path, $maxreq, $cb) = @_;	813	my ($path, $maxreq, $cb) = @_;
484		814
		815	my $pri = aioreq_pri;
		816
485	my $grp = aio_group $cb;	817	my $grp = aio_group $cb;
486		818
487	$maxreq = 6 if $maxreq <= 0;	819	$maxreq = 4 if $maxreq <= 0;
488		820
489	# stat once	821	# stat once
		822	aioreq_pri $pri;
490	add $grp aio_stat $path, sub {	823	add $grp aio_stat $path, sub {
491	return $grp->result () if $_[0];	824	return $grp->result () if $_[0];
492	my $now = time;	825	my $now = time;
493	my $hash1 = join ":", (stat _)[0,1,3,7,9];	826	my $hash1 = join ":", (stat _)[0,1,3,7,9];
494		827
495	# read the directory entries	828	# read the directory entries
		829	aioreq_pri $pri;
496	add $grp aio_readdir $path, sub {	830	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
497	my $entries = shift	831	my $entries = shift
498	or return $grp->result ();	832	or return $grp->result ();
499		833
500	# stat the dir another time	834	# stat the dir another time
		835	aioreq_pri $pri;
501	add $grp aio_stat $path, sub {	836	add $grp aio_stat $path, sub {
502	my $hash2 = join ":", (stat _)[0,1,3,7,9];	837	my $hash2 = join ":", (stat _)[0,1,3,7,9];
503		838
504	my $ndirs;	839	my $ndirs;
505		840
506	# take the slow route if anything looks fishy	841	# take the slow route if anything looks fishy
507	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	842	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
508	$ndirs = -1;	843	$ndirs = -1;
509	} else {	844	} else {
510	# if nlink == 2, we are finished	845	# if nlink == 2, we are finished
511	# on non-posix-fs's, we rely on nlink < 2	846	# for non-posix-fs's, we rely on nlink < 2
512	$ndirs = (stat _)[3] - 2	847	$ndirs = (stat _)[3] - 2
513	or return $grp->result ([], $entries);	848	or return $grp->result ([], $entries);
514	}	849	}
515		850
516	# sort into likely dirs and likely nondirs
517	# dirs == files without ".", short entries first
518	$entries = [map $_->[0],
519	sort { $b->[1] cmp $a->[1] }
520	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
521	@$entries];
522
523	my (@dirs, @nondirs);	851	my (@dirs, @nondirs);
524		852
525	my $statgrp = add $grp aio_group sub {	853	my $statgrp = add $grp aio_group sub {
526	$grp->result (\@dirs, \@nondirs);	854	$grp->result (\@dirs, \@nondirs);
527	};	855	};
528		856
529	limit $statgrp $maxreq;	857	limit $statgrp $maxreq;
530	feed $statgrp sub {	858	feed $statgrp sub {
531	return unless @$entries;	859	return unless @$entries;
532	my $entry = pop @$entries;	860	my $entry = shift @$entries;
533		861
		862	aioreq_pri $pri;
534	add $statgrp aio_stat "$path/$entry/.", sub {	863	add $statgrp aio_stat "$path/$entry/.", sub {
535	if ($_[0] < 0) {	864	if ($_[0] < 0) {
536	push @nondirs, $entry;	865	push @nondirs, $entry;
537	} else {	866	} else {
538	# need to check for real directory	867	# need to check for real directory
		868	aioreq_pri $pri;
539	add $statgrp aio_lstat "$path/$entry", sub {	869	add $statgrp aio_lstat "$path/$entry", sub {
540	if (-d _) {	870	if (-d _) {
541	push @dirs, $entry;	871	push @dirs, $entry;
542		872
543	if (!--$ndirs) {	873	unless (--$ndirs) {
544	push @nondirs, @$entries;	874	push @nondirs, @$entries;
545	$statgrp->cancel_subs;	875	feed $statgrp;
546	}	876	}
547	} else {	877	} else {
548	push @nondirs, $entry;	878	push @nondirs, $entry;
549	}	879	}
550	}	880	}
…		…
556	};	886	};
557		887
558	$grp	888	$grp
559	}	889	}
560		890
		891	=item aio_rmtree $path, $callback->($status)
		892
		893	Delete a directory tree starting (and including) C<$path>, return the
		894	status of the final C<rmdir> only. This is a composite request that
		895	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		896	everything else.
		897
		898	=cut
		899
		900	sub aio_rmtree;
		901	sub aio_rmtree($;$) {
		902	my ($path, $cb) = @_;
		903
		904	my $pri = aioreq_pri;
		905	my $grp = aio_group $cb;
		906
		907	aioreq_pri $pri;
		908	add $grp aio_scandir $path, 0, sub {
		909	my ($dirs, $nondirs) = @_;
		910
		911	my $dirgrp = aio_group sub {
		912	add $grp aio_rmdir $path, sub {
		913	$grp->result ($_[0]);
		914	};
		915	};
		916
		917	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		918	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		919
		920	add $grp $dirgrp;
		921	};
		922
		923	$grp
		924	}
		925
		926	=item aio_sync $callback->($status)
		927
		928	Asynchronously call sync and call the callback when finished.
		929
561	=item aio_fsync $fh, $callback->($status)	930	=item aio_fsync $fh, $callback->($status)
562		931
563	Asynchronously call fsync on the given filehandle and call the callback	932	Asynchronously call fsync on the given filehandle and call the callback
564	with the fsync result code.	933	with the fsync result code.
565		934
…		…
568	Asynchronously call fdatasync on the given filehandle and call the	937	Asynchronously call fdatasync on the given filehandle and call the
569	callback with the fdatasync result code.	938	callback with the fdatasync result code.
570		939
571	If this call isn't available because your OS lacks it or it couldn't be	940	If this call isn't available because your OS lacks it or it couldn't be
572	detected, it will be emulated by calling C<fsync> instead.	941	detected, it will be emulated by calling C<fsync> instead.
		942
		943	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		944
		945	Sync the data portion of the file specified by C<$offset> and C<$length>
		946	to disk (but NOT the metadata), by calling the Linux-specific
		947	sync_file_range call. If sync_file_range is not available or it returns
		948	ENOSYS, then fdatasync or fsync is being substituted.
		949
		950	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		951	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		952	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		953	manpage for details.
		954
		955	=item aio_pathsync $path, $callback->($status)
		956
		957	This request tries to open, fsync and close the given path. This is a
		958	composite request intended to sync directories after directory operations
		959	(E.g. rename). This might not work on all operating systems or have any
		960	specific effect, but usually it makes sure that directory changes get
		961	written to disc. It works for anything that can be opened for read-only,
		962	not just directories.
		963
		964	Future versions of this function might fall back to other methods when
		965	C<fsync> on the directory fails (such as calling C<sync>).
		966
		967	Passes C<0> when everything went ok, and C<-1> on error.
		968
		969	=cut
		970
		971	sub aio_pathsync($;$) {
		972	my ($path, $cb) = @_;
		973
		974	my $pri = aioreq_pri;
		975	my $grp = aio_group $cb;
		976
		977	aioreq_pri $pri;
		978	add $grp aio_open $path, O_RDONLY, 0, sub {
		979	my ($fh) = @_;
		980	if ($fh) {
		981	aioreq_pri $pri;
		982	add $grp aio_fsync $fh, sub {
		983	$grp->result ($_[0]);
		984
		985	aioreq_pri $pri;
		986	add $grp aio_close $fh;
		987	};
		988	} else {
		989	$grp->result (-1);
		990	}
		991	};
		992
		993	$grp
		994	}
		995
		996	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		997
		998	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		999	scalars (see the L<Sys::Mmap> or L<Mmap> modules for details on this, note
		1000	that the scalar must only be modified in-place while an aio operation is
		1001	pending on it).
		1002
		1003	It calls the C<msync> function of your OS, if available, with the memory
		1004	area starting at C<$offset> in the string and ending C<$length> bytes
		1005	later. If C<$length> is negative, counts from the end, and if C<$length>
		1006	is C<undef>, then it goes till the end of the string. The flags can be
		1007	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1008	C<IO::AIO::MS_SYNC>.
		1009
		1010	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1011
		1012	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1013	scalars.
		1014
		1015	It touches (reads or writes) all memory pages in the specified
		1016	range inside the scalar. All caveats and parameters are the same
		1017	as for C<aio_msync>, above, except for flags, which must be either
		1018	C<0> (which reads all pages and ensures they are instantiated) or
		1019	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1020	writing an octet from it, which dirties the page).
573		1021
574	=item aio_group $callback->(...)	1022	=item aio_group $callback->(...)
575		1023
576	This is a very special aio request: Instead of doing something, it is a	1024	This is a very special aio request: Instead of doing something, it is a
577	container for other aio requests, which is useful if you want to bundle	1025	container for other aio requests, which is useful if you want to bundle
…		…
627	=item cancel $req	1075	=item cancel $req
628		1076
629	Cancels the request, if possible. Has the effect of skipping execution	1077	Cancels the request, if possible. Has the effect of skipping execution
630	when entering the B<execute> state and skipping calling the callback when	1078	when entering the B<execute> state and skipping calling the callback when
631	entering the the B<result> state, but will leave the request otherwise	1079	entering the the B<result> state, but will leave the request otherwise
632	untouched. That means that requests that currently execute will not be	1080	untouched (with the exception of readdir). That means that requests that
633	stopped and resources held by the request will not be freed prematurely.	1081	currently execute will not be stopped and resources held by the request
		1082	will not be freed prematurely.
634		1083
635	=item cb $req $callback->(...)	1084	=item cb $req $callback->(...)
636		1085
637	Replace (or simply set) the callback registered to the request.	1086	Replace (or simply set) the callback registered to the request.
638		1087
…		…
682	=item * They can also can also be added to other IO::AIO::GRP objects.	1131	=item * They can also can also be added to other IO::AIO::GRP objects.
683		1132
684	=item * You must not add requests to a group from within the group callback (or	1133	=item * You must not add requests to a group from within the group callback (or
685	any later time).	1134	any later time).
686		1135
687	=item * This does not harmonise well with C<max_outstanding>, so best do
688	not combine C<aio_group> with it. Groups and feeders are recommended for
689	this kind of concurrency-limiting.
690
691	=back	1136	=back
692		1137
693	Their lifetime, simplified, looks like this: when they are empty, they	1138	Their lifetime, simplified, looks like this: when they are empty, they
694	will finish very quickly. If they contain only requests that are in the	1139	will finish very quickly. If they contain only requests that are in the
695	C<done> state, they will also finish. Otherwise they will continue to	1140	C<done> state, they will also finish. Otherwise they will continue to
696	exist.	1141	exist.
697		1142
698	That means after creating a group you have some time to add requests. And	1143	That means after creating a group you have some time to add requests
699	in the callbacks of those requests, you can add further requests to the	1144	(precisely before the callback has been invoked, which is only done within
700	group. And only when all those requests have finished will the the group	1145	the C<poll_cb>). And in the callbacks of those requests, you can add
701	itself finish.	1146	further requests to the group. And only when all those requests have
		1147	finished will the the group itself finish.
702		1148
703	=over 4	1149	=over 4
704		1150
705	=item add $grp ...	1151	=item add $grp ...
706		1152
…		…
715	=item $grp->cancel_subs	1161	=item $grp->cancel_subs
716		1162
717	Cancel all subrequests and clears any feeder, but not the group request	1163	Cancel all subrequests and clears any feeder, but not the group request
718	itself. Useful when you queued a lot of events but got a result early.	1164	itself. Useful when you queued a lot of events but got a result early.
719		1165
		1166	The group request will finish normally (you cannot add requests to the
		1167	group).
		1168
720	=item $grp->result (...)	1169	=item $grp->result (...)
721		1170
722	Set the result value(s) that will be passed to the group callback when all	1171	Set the result value(s) that will be passed to the group callback when all
723	subrequests have finished. By default, no argument will be passed.	1172	subrequests have finished and set the groups errno to the current value
		1173	of errno (just like calling C<errno> without an error number). By default,
		1174	no argument will be passed and errno is zero.
		1175
		1176	=item $grp->errno ([$errno])
		1177
		1178	Sets the group errno value to C<$errno>, or the current value of errno
		1179	when the argument is missing.
		1180
		1181	Every aio request has an associated errno value that is restored when
		1182	the callback is invoked. This method lets you change this value from its
		1183	default (0).
		1184
		1185	Calling C<result> will also set errno, so make sure you either set C<$!>
		1186	before the call to C<result>, or call c<errno> after it.
724		1187
725	=item feed $grp $callback->($grp)	1188	=item feed $grp $callback->($grp)
726		1189
727	Sets a feeder/generator on this group: every group can have an attached	1190	Sets a feeder/generator on this group: every group can have an attached
728	generator that generates requests if idle. The idea behind this is that,	1191	generator that generates requests if idle. The idea behind this is that,
729	although you could just queue as many requests as you want in a group,	1192	although you could just queue as many requests as you want in a group,
730	this might starve other requests for a potentially long time. For	1193	this might starve other requests for a potentially long time. For example,
731	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1194	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
732	requests, delaying any later requests for a long time.	1195	delaying any later requests for a long time.
733		1196
734	To avoid this, and allow incremental generation of requests, you can	1197	To avoid this, and allow incremental generation of requests, you can
735	instead a group and set a feeder on it that generates those requests. The	1198	instead a group and set a feeder on it that generates those requests. The
736	feed callback will be called whenever there are few enough (see C<limit>,	1199	feed callback will be called whenever there are few enough (see C<limit>,
737	below) requests active in the group itself and is expected to queue more	1200	below) requests active in the group itself and is expected to queue more
…		…
741	not impose any limits).	1204	not impose any limits).
742		1205
743	If the feed does not queue more requests when called, it will be	1206	If the feed does not queue more requests when called, it will be
744	automatically removed from the group.	1207	automatically removed from the group.
745		1208
746	If the feed limit is C<0>, it will be set to C<2> automatically.	1209	If the feed limit is C<0> when this method is called, it will be set to
		1210	C<2> automatically.
747		1211
748	Example:	1212	Example:
749		1213
750	# stat all files in @files, but only ever use four aio requests concurrently:	1214	# stat all files in @files, but only ever use four aio requests concurrently:
751		1215
…		…
763	Sets the feeder limit for the group: The feeder will be called whenever	1227	Sets the feeder limit for the group: The feeder will be called whenever
764	the group contains less than this many requests.	1228	the group contains less than this many requests.
765		1229
766	Setting the limit to C<0> will pause the feeding process.	1230	Setting the limit to C<0> will pause the feeding process.
767		1231
		1232	The default value for the limit is C<0>, but note that setting a feeder
		1233	automatically bumps it up to C<2>.
		1234
768	=back	1235	=back
769		1236
770	=head2 SUPPORT FUNCTIONS	1237	=head2 SUPPORT FUNCTIONS
771		1238
		1239	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1240
772	=over 4	1241	=over 4
773		1242
774	=item $fileno = IO::AIO::poll_fileno	1243	=item $fileno = IO::AIO::poll_fileno
775		1244
776	Return the I<request result pipe file descriptor>. This filehandle must be	1245	Return the I<request result pipe file descriptor>. This filehandle must be
777	polled for reading by some mechanism outside this module (e.g. Event or	1246	polled for reading by some mechanism outside this module (e.g. EV, Glib,
778	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1247	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
779	to call C<poll_cb> to check the results.	1248	you have to call C<poll_cb> to check the results.
780		1249
781	See C<poll_cb> for an example.	1250	See C<poll_cb> for an example.
782		1251
783	=item IO::AIO::poll_cb	1252	=item IO::AIO::poll_cb
784		1253
785	Process all outstanding events on the result pipe. You have to call this	1254	Process some outstanding events on the result pipe. You have to call this
786	regularly. Returns the number of events processed. Returns immediately	1255	regularly. Returns C<0> if all events could be processed, or C<-1> if it
787	when no events are outstanding.	1256	returned earlier for whatever reason. Returns immediately when no events
		1257	are outstanding. The amount of events processed depends on the settings of
		1258	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1259
		1260	If not all requests were processed for whatever reason, the filehandle
		1261	will still be ready when C<poll_cb> returns, so normally you don't have to
		1262	do anything special to have it called later.
788		1263
789	Example: Install an Event watcher that automatically calls	1264	Example: Install an Event watcher that automatically calls
790	IO::AIO::poll_cb with high priority:	1265	IO::AIO::poll_cb with high priority (more examples can be found in the
		1266	SYNOPSIS section, at the top of this document):
791		1267
792	Event->io (fd => IO::AIO::poll_fileno,	1268	Event->io (fd => IO::AIO::poll_fileno,
793	poll => 'r', async => 1,	1269	poll => 'r', async => 1,
794	cb => \&IO::AIO::poll_cb);	1270	cb => \&IO::AIO::poll_cb);
795		1271
		1272	=item IO::AIO::max_poll_reqs $nreqs
		1273
		1274	=item IO::AIO::max_poll_time $seconds
		1275
		1276	These set the maximum number of requests (default C<0>, meaning infinity)
		1277	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1278	the maximum amount of time (default C<0>, meaning infinity) spent in
		1279	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1280	of time C<poll_cb> is allowed to use).
		1281
		1282	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1283	syscall per request processed, which is not normally a problem unless your
		1284	callbacks are really really fast or your OS is really really slow (I am
		1285	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1286
		1287	Setting these is useful if you want to ensure some level of
		1288	interactiveness when perl is not fast enough to process all requests in
		1289	time.
		1290
		1291	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1292
		1293	Example: Install an Event watcher that automatically calls
		1294	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1295	program get the CPU sometimes even under high AIO load.
		1296
		1297	# try not to spend much more than 0.1s in poll_cb
		1298	IO::AIO::max_poll_time 0.1;
		1299
		1300	# use a low priority so other tasks have priority
		1301	Event->io (fd => IO::AIO::poll_fileno,
		1302	poll => 'r', nice => 1,
		1303	cb => &IO::AIO::poll_cb);
		1304
796	=item IO::AIO::poll_wait	1305	=item IO::AIO::poll_wait
797		1306
		1307	If there are any outstanding requests and none of them in the result
798	Wait till the result filehandle becomes ready for reading (simply does a	1308	phase, wait till the result filehandle becomes ready for reading (simply
799	C<select> on the filehandle. This is useful if you want to synchronously wait	1309	does a C<select> on the filehandle. This is useful if you want to
800	for some requests to finish).	1310	synchronously wait for some requests to finish).
801		1311
802	See C<nreqs> for an example.	1312	See C<nreqs> for an example.
803		1313
		1314	=item IO::AIO::poll
		1315
		1316	Waits until some requests have been handled.
		1317
		1318	Returns the number of requests processed, but is otherwise strictly
		1319	equivalent to:
		1320
		1321	IO::AIO::poll_wait, IO::AIO::poll_cb
		1322
804	=item IO::AIO::nreqs	1323	=item IO::AIO::flush
805		1324
806	Returns the number of requests currently outstanding (i.e. for which their	1325	Wait till all outstanding AIO requests have been handled.
807	callback has not been invoked yet).
808		1326
809	Example: wait till there are no outstanding requests anymore:	1327	Strictly equivalent to:
810		1328
811	IO::AIO::poll_wait, IO::AIO::poll_cb	1329	IO::AIO::poll_wait, IO::AIO::poll_cb
812	while IO::AIO::nreqs;	1330	while IO::AIO::nreqs;
813		1331
814	=item IO::AIO::flush	1332	=back
815		1333
816	Wait till all outstanding AIO requests have been handled.	1334	=head3 CONTROLLING THE NUMBER OF THREADS
817		1335
818	Strictly equivalent to:	1336	=over
819
820	IO::AIO::poll_wait, IO::AIO::poll_cb
821	while IO::AIO::nreqs;
822
823	=item IO::AIO::poll
824
825	Waits until some requests have been handled.
826
827	Strictly equivalent to:
828
829	IO::AIO::poll_wait, IO::AIO::poll_cb
830	if IO::AIO::nreqs;
831		1337
832	=item IO::AIO::min_parallel $nthreads	1338	=item IO::AIO::min_parallel $nthreads
833		1339
834	Set the minimum number of AIO threads to C<$nthreads>. The current	1340	Set the minimum number of AIO threads to C<$nthreads>. The current
835	default is C<8>, which means eight asynchronous operations can execute	1341	default is C<8>, which means eight asynchronous operations can execute
836	concurrently at any one time (the number of outstanding requests,	1342	concurrently at any one time (the number of outstanding requests,
837	however, is unlimited).	1343	however, is unlimited).
838		1344
839	IO::AIO starts threads only on demand, when an AIO request is queued and	1345	IO::AIO starts threads only on demand, when an AIO request is queued and
840	no free thread exists.	1346	no free thread exists. Please note that queueing up a hundred requests can
		1347	create demand for a hundred threads, even if it turns out that everything
		1348	is in the cache and could have been processed faster by a single thread.
841		1349
842	It is recommended to keep the number of threads relatively low, as some	1350	It is recommended to keep the number of threads relatively low, as some
843	Linux kernel versions will scale negatively with the number of threads	1351	Linux kernel versions will scale negatively with the number of threads
844	(higher parallelity => MUCH higher latency). With current Linux 2.6	1352	(higher parallelity => MUCH higher latency). With current Linux 2.6
845	versions, 4-32 threads should be fine.	1353	versions, 4-32 threads should be fine.
…		…
859	This module automatically runs C<max_parallel 0> at program end, to ensure	1367	This module automatically runs C<max_parallel 0> at program end, to ensure
860	that all threads are killed and that there are no outstanding requests.	1368	that all threads are killed and that there are no outstanding requests.
861		1369
862	Under normal circumstances you don't need to call this function.	1370	Under normal circumstances you don't need to call this function.
863		1371
		1372	=item IO::AIO::max_idle $nthreads
		1373
		1374	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1375	threads that did not get a request to process within 10 seconds). That
		1376	means if a thread becomes idle while C<$nthreads> other threads are also
		1377	idle, it will free its resources and exit.
		1378
		1379	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1380	to allow for extremely high load situations, but want to free resources
		1381	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1382
		1383	The default is probably ok in most situations, especially if thread
		1384	creation is fast. If thread creation is very slow on your system you might
		1385	want to use larger values.
		1386
864	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1387	=item IO::AIO::max_outstanding $maxreqs
865		1388
866	[DEPRECATED]	1389	This is a very bad function to use in interactive programs because it
		1390	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1391	use an C<aio_group> together with a feed callback.
867		1392
868	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1393	Sets the maximum number of outstanding requests to C<$nreqs>. If you
869	try to queue up more than this number of requests, the caller will block until	1394	do queue up more than this number of requests, the next call to the
870	some requests have been handled.	1395	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1396	function will block until the limit is no longer exceeded.
871		1397
872	The default is very large, so normally there is no practical limit. If you	1398	The default value is very large, so there is no practical limit on the
873	queue up many requests in a loop it often improves speed if you set	1399	number of outstanding requests.
874	this to a relatively low number, such as C<100>.
875		1400
876	This function does not work well together with C<aio_group>'s, and their	1401	You can still queue as many requests as you want. Therefore,
877	feeder interface is better suited to limiting concurrency, so do not use	1402	C<max_outstanding> is mainly useful in simple scripts (with low values) or
878	this function.	1403	as a stop gap to shield against fatal memory overflow (with large values).
879
880	Under normal circumstances you don't need to call this function.
881		1404
882	=back	1405	=back
883		1406
		1407	=head3 STATISTICAL INFORMATION
		1408
		1409	=over
		1410
		1411	=item IO::AIO::nreqs
		1412
		1413	Returns the number of requests currently in the ready, execute or pending
		1414	states (i.e. for which their callback has not been invoked yet).
		1415
		1416	Example: wait till there are no outstanding requests anymore:
		1417
		1418	IO::AIO::poll_wait, IO::AIO::poll_cb
		1419	while IO::AIO::nreqs;
		1420
		1421	=item IO::AIO::nready
		1422
		1423	Returns the number of requests currently in the ready state (not yet
		1424	executed).
		1425
		1426	=item IO::AIO::npending
		1427
		1428	Returns the number of requests currently in the pending state (executed,
		1429	but not yet processed by poll_cb).
		1430
		1431	=back
		1432
		1433	=head3 MISCELLANEOUS FUNCTIONS
		1434
		1435	IO::AIO implements some functions that might be useful, but are not
		1436	asynchronous.
		1437
		1438	=over 4
		1439
		1440	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1441
		1442	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1443	but is blocking (this makes most sense if you know the input data is
		1444	likely cached already and the output filehandle is set to non-blocking
		1445	operations).
		1446
		1447	Returns the number of bytes copied, or C<-1> on error.
		1448
		1449	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1450
		1451	Simply calls the C<posix_fadvise> function (see it's
		1452	manpage for details). The following advice constants are
		1453	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1454	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1455	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1456
		1457	On systems that do not implement C<posix_fadvise>, this function returns
		1458	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1459
		1460	=back
		1461
884	=cut	1462	=cut
885		1463
886	# support function to convert a fd into a perl filehandle
887	sub _fd2fh {
888	return undef if $_[0] < 0;
889
890	# try to generate nice filehandles
891	my $sym = "IO::AIO::fd#$_[0]";
892	local *$sym;
893
894	open *$sym, "+<&=$_[0]" # usually works under any unix
895	or open *$sym, "<&=$_[0]" # cygwin needs this
896	or open *$sym, ">&=$_[0]" # or this
897	or return undef;
898
899	*$sym
900	}
901
902	min_parallel 8;	1464	min_parallel 8;
903		1465
904	END {	1466	END { flush }
905	max_parallel 0;
906	}
907		1467
908	1;	1468	1;
909		1469
910	=head2 FORK BEHAVIOUR	1470	=head2 FORK BEHAVIOUR
911		1471
…		…
931	bytes of memory. In addition, stat requests need a stat buffer (possibly	1491	bytes of memory. In addition, stat requests need a stat buffer (possibly
932	a few hundred bytes), readdir requires a result buffer and so on. Perl	1492	a few hundred bytes), readdir requires a result buffer and so on. Perl
933	scalars and other data passed into aio requests will also be locked and	1493	scalars and other data passed into aio requests will also be locked and
934	will consume memory till the request has entered the done state.	1494	will consume memory till the request has entered the done state.
935		1495
936	This is now awfully much, so queuing lots of requests is not usually a	1496	This is not awfully much, so queuing lots of requests is not usually a
937	problem.	1497	problem.
938		1498
939	Per-thread usage:	1499	Per-thread usage:
940		1500
941	In the execution phase, some aio requests require more memory for	1501	In the execution phase, some aio requests require more memory for
…		…
946		1506
947	Known bugs will be fixed in the next release.	1507	Known bugs will be fixed in the next release.
948		1508
949	=head1 SEE ALSO	1509	=head1 SEE ALSO
950		1510
951	L<Coro::AIO>.	1511	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1512	more natural syntax.
952		1513
953	=head1 AUTHOR	1514	=head1 AUTHOR
954		1515
955	Marc Lehmann <schmorp@schmorp.de>	1516	Marc Lehmann <schmorp@schmorp.de>
956	http://home.schmorp.de/	1517	http://home.schmorp.de/

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