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Revision 1.67 by root, Tue Oct 24 02:25:16 2006 UTC vs.
Revision 1.149 by root, Sat Jun 6 18:19:35 2009 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
…		…
18	};	19	};
19		20
20	# version 2+ has request and group objects	21	# version 2+ has request and group objects
21	use IO::AIO 2;	22	use IO::AIO 2;
22		23
		24	aioreq_pri 4; # give next request a very high priority
23	my $req = aio_unlink "/tmp/file", sub { };	25	my $req = aio_unlink "/tmp/file", sub { };
24	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
25		27
26	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
28		30
		31	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		32	use AnyEvent::AIO;
		33
29	# AnyEvent integration	34	# EV integration
30	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	35	my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
31	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
32		36
33	# Event integration	37	# Event integration
34	Event->io (fd => IO::AIO::poll_fileno,	38	Event->io (fd => IO::AIO::poll_fileno,
35	poll => 'r',	39	poll => 'r',
36	cb => \&IO::AIO::poll_cb);	40	cb => \&IO::AIO::poll_cb);
…		…
50	=head1 DESCRIPTION	54	=head1 DESCRIPTION
51		55
52	This module implements asynchronous I/O using whatever means your	56	This module implements asynchronous I/O using whatever means your
53	operating system supports.	57	operating system supports.
54		58
		59	Asynchronous means that operations that can normally block your program
		60	(e.g. reading from disk) will be done asynchronously: the operation
		61	will still block, but you can do something else in the meantime. This
		62	is extremely useful for programs that need to stay interactive even
		63	when doing heavy I/O (GUI programs, high performance network servers
		64	etc.), but can also be used to easily do operations in parallel that are
		65	normally done sequentially, e.g. stat'ing many files, which is much faster
		66	on a RAID volume or over NFS when you do a number of stat operations
		67	concurrently.
		68
		69	While most of this works on all types of file descriptors (for
		70	example sockets), using these functions on file descriptors that
		71	support nonblocking operation (again, sockets, pipes etc.) is very
		72	inefficient. Use an event loop for that (such as the L<Event|Event>
		73	module): IO::AIO will naturally fit into such an event loop itself.
		74
55	Currently, a number of threads are started that execute your read/writes	75	In this version, a number of threads are started that execute your
56	and signal their completion. You don't need thread support in perl, and	76	requests and signal their completion. You don't need thread support
57	the threads created by this module will not be visible to perl. In the	77	in perl, and the threads created by this module will not be visible
58	future, this module might make use of the native aio functions available	78	to perl. In the future, this module might make use of the native aio
59	on many operating systems. However, they are often not well-supported	79	functions available on many operating systems. However, they are often
60	(Linux doesn't allow them on normal files currently, for example),	80	not well-supported or restricted (GNU/Linux doesn't allow them on normal
61	and they would only support aio_read and aio_write, so the remaining	81	files currently, for example), and they would only support aio_read and
62	functionality would have to be implemented using threads anyway.	82	aio_write, so the remaining functionality would have to be implemented
		83	using threads anyway.
63		84
64	Although the module will work with in the presence of other threads, it is	85	Although the module will work in the presence of other (Perl-) threads,
65	currently not reentrant, so use appropriate locking yourself, always call	86	it is currently not reentrant in any way, so use appropriate locking
66	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	87	yourself, always call C<poll_cb> from within the same thread, or never
67	C<aio_> functions) recursively.	88	call C<poll_cb> (or other C<aio_> functions) recursively.
		89
		90	=head2 EXAMPLE
		91
		92	This is a simple example that uses the Event module and loads
		93	F</etc/passwd> asynchronously:
		94
		95	use Fcntl;
		96	use Event;
		97	use IO::AIO;
		98
		99	# register the IO::AIO callback with Event
		100	Event->io (fd => IO::AIO::poll_fileno,
		101	poll => 'r',
		102	cb => \&IO::AIO::poll_cb);
		103
		104	# queue the request to open /etc/passwd
		105	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		106	my $fh = shift
		107	or die "error while opening: $!";
		108
		109	# stat'ing filehandles is generally non-blocking
		110	my $size = -s $fh;
		111
		112	# queue a request to read the file
		113	my $contents;
		114	aio_read $fh, 0, $size, $contents, 0, sub {
		115	$_[0] == $size
		116	or die "short read: $!";
		117
		118	close $fh;
		119
		120	# file contents now in $contents
		121	print $contents;
		122
		123	# exit event loop and program
		124	Event::unloop;
		125	};
		126	};
		127
		128	# possibly queue up other requests, or open GUI windows,
		129	# check for sockets etc. etc.
		130
		131	# process events as long as there are some:
		132	Event::loop;
		133
		134	=head1 REQUEST ANATOMY AND LIFETIME
		135
		136	Every C<aio_*> function creates a request. which is a C data structure not
		137	directly visible to Perl.
		138
		139	If called in non-void context, every request function returns a Perl
		140	object representing the request. In void context, nothing is returned,
		141	which saves a bit of memory.
		142
		143	The perl object is a fairly standard ref-to-hash object. The hash contents
		144	are not used by IO::AIO so you are free to store anything you like in it.
		145
		146	During their existance, aio requests travel through the following states,
		147	in order:
		148
		149	=over 4
		150
		151	=item ready
		152
		153	Immediately after a request is created it is put into the ready state,
		154	waiting for a thread to execute it.
		155
		156	=item execute
		157
		158	A thread has accepted the request for processing and is currently
		159	executing it (e.g. blocking in read).
		160
		161	=item pending
		162
		163	The request has been executed and is waiting for result processing.
		164
		165	While request submission and execution is fully asynchronous, result
		166	processing is not and relies on the perl interpreter calling C<poll_cb>
		167	(or another function with the same effect).
		168
		169	=item result
		170
		171	The request results are processed synchronously by C<poll_cb>.
		172
		173	The C<poll_cb> function will process all outstanding aio requests by
		174	calling their callbacks, freeing memory associated with them and managing
		175	any groups they are contained in.
		176
		177	=item done
		178
		179	Request has reached the end of its lifetime and holds no resources anymore
		180	(except possibly for the Perl object, but its connection to the actual
		181	aio request is severed and calling its methods will either do nothing or
		182	result in a runtime error).
		183
		184	=back
68		185
69	=cut	186	=cut
70		187
71	package IO::AIO;	188	package IO::AIO;
		189
		190	use Carp ();
72		191
73	no warnings;	192	no warnings;
74	use strict 'vars';	193	use strict 'vars';
75		194
76	use base 'Exporter';	195	use base 'Exporter';
77		196
78	BEGIN {	197	BEGIN {
79	our $VERSION = '2.0';	198	our $VERSION = '3.2';
80		199
81	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	200	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
82	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	201	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
83	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	202	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
84	aio_group aio_nop);	203	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
		204	aio_rename aio_link aio_move aio_copy aio_group
		205	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		206	aio_chmod aio_utime aio_truncate);
		207
85	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	208	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
86	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	209	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
87	min_parallel max_parallel max_outstanding nreqs);	210	min_parallel max_parallel max_idle
		211	nreqs nready npending nthreads
		212	max_poll_time max_poll_reqs);
		213
		214	push @AIO_REQ, qw(aio_busy); # not exported
88		215
89	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	216	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
90		217
91	require XSLoader;	218	require XSLoader;
92	XSLoader::load ("IO::AIO", $VERSION);	219	XSLoader::load ("IO::AIO", $VERSION);
93	}	220	}
94		221
95	=head1 FUNCTIONS	222	=head1 FUNCTIONS
96		223
97	=head2 AIO FUNCTIONS	224	=head2 AIO REQUEST FUNCTIONS
98		225
99	All the C<aio_*> calls are more or less thin wrappers around the syscall	226	All the C<aio_*> calls are more or less thin wrappers around the syscall
100	with the same name (sans C<aio_>). The arguments are similar or identical,	227	with the same name (sans C<aio_>). The arguments are similar or identical,
101	and they all accept an additional (and optional) C<$callback> argument	228	and they all accept an additional (and optional) C<$callback> argument
102	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
103	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
104	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
105	syscall has been executed asynchronously.	232	syscall has been executed asynchronously.
106		233
107	All functions expecting a filehandle keep a copy of the filehandle	234	All functions expecting a filehandle keep a copy of the filehandle
108	internally until the request has finished.	235	internally until the request has finished.
109		236
110	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
111	manipulation of those requests while they are in-flight.	238	further manipulation of those requests while they are in-flight.
112		239
113	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
114	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
115	request is being executed, the current working directory could have	242	request is being executed, the current working directory could have
116	changed. Alternatively, you can make sure that you never change the	243	changed. Alternatively, you can make sure that you never change the
117	current working directory.	244	current working directory anywhere in the program and then use relative
		245	paths.
118		246
119	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
120	always pass in filenames you got from outside (command line, readdir	248	in filenames you got from outside (command line, readdir etc.) without
121	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
122	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
123	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)
124	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.
125		256
126	=over 4	257	=over 4
		258
		259	=item $prev_pri = aioreq_pri [$pri]
		260
		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
		264	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		265	and C<4>, respectively. Requests with higher priority will be serviced
		266	first.
		267
		268	The priority will be reset to C<0> after each call to one of the C<aio_*>
		269	functions.
		270
		271	Example: open a file with low priority, then read something from it with
		272	higher priority so the read request is serviced before other low priority
		273	open requests (potentially spamming the cache):
		274
		275	aioreq_pri -3;
		276	aio_open ..., sub {
		277	return unless $_[0];
		278
		279	aioreq_pri -2;
		280	aio_read $_[0], ..., sub {
		281	...
		282	};
		283	};
		284
		285
		286	=item aioreq_nice $pri_adjust
		287
		288	Similar to C<aioreq_pri>, but subtracts the given value from the current
		289	priority, so the effect is cumulative.
		290
127		291
128	=item aio_open $pathname, $flags, $mode, $callback->($fh)	292	=item aio_open $pathname, $flags, $mode, $callback->($fh)
129		293
130	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
131	created filehandle for the file.	295	created filehandle for the file.
…		…
137	list. They are the same as used by C<sysopen>.	301	list. They are the same as used by C<sysopen>.
138		302
139	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
140	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>,
141	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,
142	and C<0666> or C<0777> if you do).	306	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		307	by the umask in effect then the request is being executed, so better never
		308	change the umask.
143		309
144	Example:	310	Example:
145		311
146	aio_open "/etc/passwd", O_RDONLY, 0, sub {	312	aio_open "/etc/passwd", O_RDONLY, 0, sub {
147	if ($_[0]) {	313	if ($_[0]) {
…		…
150	} else {	316	} else {
151	die "open failed: $!\n";	317	die "open failed: $!\n";
152	}	318	}
153	};	319	};
154		320
		321
155	=item aio_close $fh, $callback->($status)	322	=item aio_close $fh, $callback->($status)
156		323
157	Asynchronously close a file and call the callback with the result	324	Asynchronously close a file and call the callback with the result
158	code. I<WARNING:> although accepted, you should not pass in a perl	325	code.
159	filehandle here, as perl will likely close the file descriptor another
160	time when the filehandle is destroyed. Normally, you can safely call perls
161	C<close> or just let filehandles go out of scope.
162		326
163	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
164	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
165		338
166	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	339	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
167		340
168	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	341	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
169		342
170	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
171	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<$dataoffset>
172	callback without the actual number of bytes read (or -1 on error, just	345	and calls the callback without the actual number of bytes read (or -1 on
173	like the syscall).	346	error, just like the syscall).
		347
		348	C<aio_read> will, like C<sysread>, shrink or grow the C<$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<$data>.
174		360
175	The C<$data> scalar I<MUST NOT> be modified in any way while the request	361	The C<$data> scalar I<MUST NOT> be modified in any way while the request
176	is outstanding. Modifying it can result in segfaults or WW3 (if the	362	is outstanding. Modifying it can result in segfaults or World War III (if
177	necessary/optional hardware is installed).	363	the necessary/optional hardware is installed).
178		364
179	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	365	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
180	offset C<0> within the scalar:	366	offset C<0> within the scalar:
181		367
182	aio_read $fh, 7, 15, $buffer, 0, sub {	368	aio_read $fh, 7, 15, $buffer, 0, sub {
183	$_[0] > 0 or die "read error: $!";	369	$_[0] > 0 or die "read error: $!";
184	print "read $_[0] bytes: <$buffer>\n";	370	print "read $_[0] bytes: <$buffer>\n";
185	};	371	};
186		372
187	=item aio_move $srcpath, $dstpath, $callback->($status)
188
189	[EXPERIMENTAL due to internal aio_group use]
190
191	Try to move the I<file> (directories not supported as either source or
192	destination) from C<$srcpath> to C<$dstpath> and call the callback with
193	the C<0> (error) or C<-1> ok.
194
195	This is a composite request that tries to rename(2) the file first. If
196	rename files with C<EXDEV>, it creates the destination file with mode 0200
197	and copies the contents of the source file into it using C<aio_sendfile>,
198	followed by restoring atime, mtime, access mode and uid/gid, in that
199	order, and unlinking the C<$srcpath>.
200
201	If an error occurs, the partial destination file will be unlinked, if
202	possible, except when setting atime, mtime, access mode and uid/gid, where
203	errors are being ignored.
204
205	=cut
206
207	sub aio_move($$$) {
208	my ($src, $dst, $cb) = @_;
209
210	my $grp = aio_group $cb;
211
212	add $grp aio_rename $src, $dst, sub {
213	if ($_[0] && $! == EXDEV) {
214	add $grp aio_open $src, O_RDONLY, 0, sub {
215	if (my $src_fh = $_[0]) {
216	my @stat = stat $src_fh;
217
218	add $grp aio_open $dst, O_WRONLY, 0200, sub {
219	if (my $dst_fh = $_[0]) {
220	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
221	close $src_fh;
222
223	if ($_[0] == $stat[7]) {
224	utime $stat[8], $stat[9], $dst;
225	chmod $stat[2] & 07777, $dst_fh;
226	chown $stat[4], $stat[5], $dst_fh;
227	close $dst_fh;
228
229	add $grp aio_unlink $src, sub {
230	$grp->result ($_[0]);
231	};
232	} else {
233	my $errno = $!;
234	add $grp aio_unlink $dst, sub {
235	$! = $errno;
236	$grp->result (-1);
237	};
238	}
239	};
240	} else {
241	$grp->result (-1);
242	}
243	},
244
245	} else {
246	$grp->result (-1);
247	}
248	};
249	} else {
250	$grp->result ($_[0]);
251	}
252	};
253
254	$grp
255	}
256		373
257	=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)
258		375
259	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
260	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
…		…
274	C<$in_fh> than are written, and there is no way to find out how many	391	C<$in_fh> than are written, and there is no way to find out how many
275	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	392	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
276	provides the number of bytes written to C<$out_fh>. Only if the result	393	provides the number of bytes written to C<$out_fh>. Only if the result
277	value equals C<$length> one can assume that C<$length> bytes have been	394	value equals C<$length> one can assume that C<$length> bytes have been
278	read.	395	read.
		396
279		397
280	=item aio_readahead $fh,$offset,$length, $callback->($retval)	398	=item aio_readahead $fh,$offset,$length, $callback->($retval)
281		399
282	C<aio_readahead> populates the page cache with data from a file so that	400	C<aio_readahead> populates the page cache with data from a file so that
283	subsequent reads from that file will not block on disk I/O. The C<$offset>	401	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
289	file. The current file offset of the file is left unchanged.	407	file. The current file offset of the file is left unchanged.
290		408
291	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	409	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
292	emulated by simply reading the data, which would have a similar effect.	410	emulated by simply reading the data, which would have a similar effect.
293		411
		412
294	=item aio_stat $fh_or_path, $callback->($status)	413	=item aio_stat $fh_or_path, $callback->($status)
295		414
296	=item aio_lstat $fh, $callback->($status)	415	=item aio_lstat $fh, $callback->($status)
297		416
298	Works like perl's C<stat> or C<lstat> in void context. The callback will	417	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
311	aio_stat "/etc/passwd", sub {	430	aio_stat "/etc/passwd", sub {
312	$_[0] and die "stat failed: $!";	431	$_[0] and die "stat failed: $!";
313	print "size is ", -s _, "\n";	432	print "size is ", -s _, "\n";
314	};	433	};
315		434
		435
		436	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		437
		438	Works like perl's C<utime> function (including the special case of $atime
		439	and $mtime being undef). Fractional times are supported if the underlying
		440	syscalls support them.
		441
		442	When called with a pathname, uses utimes(2) if available, otherwise
		443	utime(2). If called on a file descriptor, uses futimes(2) if available,
		444	otherwise returns ENOSYS, so this is not portable.
		445
		446	Examples:
		447
		448	# set atime and mtime to current time (basically touch(1)):
		449	aio_utime "path", undef, undef;
		450	# set atime to current time and mtime to beginning of the epoch:
		451	aio_utime "path", time, undef; # undef==0
		452
		453
		454	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		455
		456	Works like perl's C<chown> function, except that C<undef> for either $uid
		457	or $gid is being interpreted as "do not change" (but -1 can also be used).
		458
		459	Examples:
		460
		461	# same as "chown root path" in the shell:
		462	aio_chown "path", 0, -1;
		463	# same as above:
		464	aio_chown "path", 0, undef;
		465
		466
		467	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		468
		469	Works like truncate(2) or ftruncate(2).
		470
		471
		472	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		473
		474	Works like perl's C<chmod> function.
		475
		476
316	=item aio_unlink $pathname, $callback->($status)	477	=item aio_unlink $pathname, $callback->($status)
317		478
318	Asynchronously unlink (delete) a file and call the callback with the	479	Asynchronously unlink (delete) a file and call the callback with the
319	result code.	480	result code.
320		481
		482
		483	=item aio_mknod $path, $mode, $dev, $callback->($status)
		484
		485	[EXPERIMENTAL]
		486
		487	Asynchronously create a device node (or fifo). See mknod(2).
		488
		489	The only (POSIX-) portable way of calling this function is:
		490
		491	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		492
		493
321	=item aio_link $srcpath, $dstpath, $callback->($status)	494	=item aio_link $srcpath, $dstpath, $callback->($status)
322		495
323	Asynchronously create a new link to the existing object at C<$srcpath> at	496	Asynchronously create a new link to the existing object at C<$srcpath> at
324	the path C<$dstpath> and call the callback with the result code.	497	the path C<$dstpath> and call the callback with the result code.
325		498
		499
326	=item aio_symlink $srcpath, $dstpath, $callback->($status)	500	=item aio_symlink $srcpath, $dstpath, $callback->($status)
327		501
328	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	502	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
329	the path C<$dstpath> and call the callback with the result code.	503	the path C<$dstpath> and call the callback with the result code.
330		504
		505
		506	=item aio_readlink $path, $callback->($link)
		507
		508	Asynchronously read the symlink specified by C<$path> and pass it to
		509	the callback. If an error occurs, nothing or undef gets passed to the
		510	callback.
		511
		512
331	=item aio_rename $srcpath, $dstpath, $callback->($status)	513	=item aio_rename $srcpath, $dstpath, $callback->($status)
332		514
333	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	515	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
334	rename(2) and call the callback with the result code.	516	rename(2) and call the callback with the result code.
335		517
		518
		519	=item aio_mkdir $pathname, $mode, $callback->($status)
		520
		521	Asynchronously mkdir (create) a directory and call the callback with
		522	the result code. C<$mode> will be modified by the umask at the time the
		523	request is executed, so do not change your umask.
		524
		525
336	=item aio_rmdir $pathname, $callback->($status)	526	=item aio_rmdir $pathname, $callback->($status)
337		527
338	Asynchronously rmdir (delete) a directory and call the callback with the	528	Asynchronously rmdir (delete) a directory and call the callback with the
339	result code.	529	result code.
		530
340		531
341	=item aio_readdir $pathname, $callback->($entries)	532	=item aio_readdir $pathname, $callback->($entries)
342		533
343	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	534	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
344	directory (i.e. opendir + readdir + closedir). The entries will not be	535	directory (i.e. opendir + readdir + closedir). The entries will not be
345	sorted, and will B<NOT> include the C<.> and C<..> entries.	536	sorted, and will B<NOT> include the C<.> and C<..> entries.
346		537
347	The callback a single argument which is either C<undef> or an array-ref	538	The callback is passed a single argument which is either C<undef> or an
348	with the filenames.	539	array-ref with the filenames.
		540
		541
		542	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		543
		544	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		545	behaviour and output format. In case of an error, C<$entries> will be
		546	C<undef>.
		547
		548	The flags are a combination of the following constants, ORed together (the
		549	flags will also be passed to the callback, possibly modified):
		550
		551	=over 4
		552
		553	=item AIO::READDIR_DENTS
		554
		555	When this flag is off, then the callback gets an arrayref with of names
		556	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		557	C<[$name, $inode, $type]> arrayrefs, each describing a single directory
		558	entry in more detail.
		559
		560	C<$name> is the name of the entry.
		561
		562	C<$inode> is the inode number (which might not be exact on systems with 64
		563	bit inode numbers and 32 bit perls). On systems that do not deliver the
		564	inode information, this will always be zero.
		565
		566	C<$type> is one of the C<AIO::DT_xxx> constants:
		567
		568	C<AIO::DT_UNKNOWN>, C<AIO::DT_FIFO>, C<AIO::DT_CHR>, C<AIO::DT_DIR>,
		569	C<AIO::DT_BLK>, C<AIO::DT_REG>, C<AIO::DT_LNK>, C<AIO::DT_SOCK>,
		570	C<AIO::DT_WHT>.
		571
		572	C<AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		573	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		574	scalars are read-only: you can not modify them.
		575
		576	=item AIO::READDIR_DIRS_FIRST
		577
		578	When this flag is set, then the names will be returned in an order where
		579	likely directories come first. This is useful when you need to quickly
		580	find directories, or you want to find all directories while avoiding to
		581	stat() each entry.
		582
		583	If the system returns type information in readdir, then this is used
		584	to find directories directly. Otherwise, likely directories are files
		585	beginning with ".", or otherwise files with no dots, of which files with
		586	short names are tried first.
		587
		588	=item AIO::READDIR_STAT_ORDER
		589
		590	When this flag is set, then the names will be returned in an order
		591	suitable for stat()'ing each one. That is, when you plan to stat()
		592	all files in the given directory, then the returned order will likely
		593	be fastest.
		594
		595	If both this flag and IO::READDIR_DIRS_FIRST are specified, then the
		596	likely dirs come first, resulting in a less optimal stat order.
		597
		598	=item AIO::READDIR_FOUND_UNKNOWN
		599
		600	This flag should not be set when calling C<aio_readdirx>. Instead, it
		601	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		602	C<AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		603	C<$type>'s are known, which can be used to speed up some algorithms.
		604
		605	=back
		606
		607
		608	=item aio_load $path, $data, $callback->($status)
		609
		610	This is a composite request that tries to fully load the given file into
		611	memory. Status is the same as with aio_read.
		612
		613	=cut
		614
		615	sub aio_load($$;$) {
		616	my ($path, undef, $cb) = @_;
		617	my $data = \$_[1];
		618
		619	my $pri = aioreq_pri;
		620	my $grp = aio_group $cb;
		621
		622	aioreq_pri $pri;
		623	add $grp aio_open $path, O_RDONLY, 0, sub {
		624	my $fh = shift
		625	or return $grp->result (-1);
		626
		627	aioreq_pri $pri;
		628	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		629	$grp->result ($_[0]);
		630	};
		631	};
		632
		633	$grp
		634	}
		635
		636	=item aio_copy $srcpath, $dstpath, $callback->($status)
		637
		638	Try to copy the I<file> (directories not supported as either source or
		639	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		640	the C<0> (error) or C<-1> ok.
		641
		642	This is a composite request that creates the destination file with
		643	mode 0200 and copies the contents of the source file into it using
		644	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		645	uid/gid, in that order.
		646
		647	If an error occurs, the partial destination file will be unlinked, if
		648	possible, except when setting atime, mtime, access mode and uid/gid, where
		649	errors are being ignored.
		650
		651	=cut
		652
		653	sub aio_copy($$;$) {
		654	my ($src, $dst, $cb) = @_;
		655
		656	my $pri = aioreq_pri;
		657	my $grp = aio_group $cb;
		658
		659	aioreq_pri $pri;
		660	add $grp aio_open $src, O_RDONLY, 0, sub {
		661	if (my $src_fh = $_[0]) {
		662	my @stat = stat $src_fh; # hmm, might bock over nfs?
		663
		664	aioreq_pri $pri;
		665	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		666	if (my $dst_fh = $_[0]) {
		667	aioreq_pri $pri;
		668	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		669	if ($_[0] == $stat[7]) {
		670	$grp->result (0);
		671	close $src_fh;
		672
		673	my $ch = sub {
		674	aioreq_pri $pri;
		675	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		676	aioreq_pri $pri;
		677	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		678	aioreq_pri $pri;
		679	add $grp aio_close $dst_fh;
		680	}
		681	};
		682	};
		683
		684	aioreq_pri $pri;
		685	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		686	if ($_[0] < 0 && $! == ENOSYS) {
		687	aioreq_pri $pri;
		688	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		689	} else {
		690	$ch->();
		691	}
		692	};
		693	} else {
		694	$grp->result (-1);
		695	close $src_fh;
		696	close $dst_fh;
		697
		698	aioreq $pri;
		699	add $grp aio_unlink $dst;
		700	}
		701	};
		702	} else {
		703	$grp->result (-1);
		704	}
		705	},
		706
		707	} else {
		708	$grp->result (-1);
		709	}
		710	};
		711
		712	$grp
		713	}
		714
		715	=item aio_move $srcpath, $dstpath, $callback->($status)
		716
		717	Try to move the I<file> (directories not supported as either source or
		718	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		719	the C<0> (error) or C<-1> ok.
		720
		721	This is a composite request that tries to rename(2) the file first; if
		722	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		723	that is successful, unlinks the C<$srcpath>.
		724
		725	=cut
		726
		727	sub aio_move($$;$) {
		728	my ($src, $dst, $cb) = @_;
		729
		730	my $pri = aioreq_pri;
		731	my $grp = aio_group $cb;
		732
		733	aioreq_pri $pri;
		734	add $grp aio_rename $src, $dst, sub {
		735	if ($_[0] && $! == EXDEV) {
		736	aioreq_pri $pri;
		737	add $grp aio_copy $src, $dst, sub {
		738	$grp->result ($_[0]);
		739
		740	if (!$_[0]) {
		741	aioreq_pri $pri;
		742	add $grp aio_unlink $src;
		743	}
		744	};
		745	} else {
		746	$grp->result ($_[0]);
		747	}
		748	};
		749
		750	$grp
		751	}
349		752
350	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	753	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
351		754
352	[EXPERIMENTAL due to internal aio_group use]
353
354	Scans a directory (similar to C<aio_readdir>) but additionally tries to	755	Scans a directory (similar to C<aio_readdir>) but additionally tries to
355	separate the entries of directory C<$path> into two sets of names, ones	756	efficiently separate the entries of directory C<$path> into two sets of
356	you can recurse into (directories or links to them), and ones you cannot	757	names, directories you can recurse into (directories), and ones you cannot
357	recurse into (everything else).	758	recurse into (everything else, including symlinks to directories).
358		759
359	C<aio_scandir> is a composite request that creates of many sub requests_	760	C<aio_scandir> is a composite request that creates of many sub requests_
360	C<$maxreq> specifies the maximum number of outstanding aio requests that	761	C<$maxreq> specifies the maximum number of outstanding aio requests that
361	this function generates. If it is C<< <= 0 >>, then a suitable default	762	this function generates. If it is C<< <= 0 >>, then a suitable default
362	will be chosen (currently 6).	763	will be chosen (currently 4).
363		764
364	On error, the callback is called without arguments, otherwise it receives	765	On error, the callback is called without arguments, otherwise it receives
365	two array-refs with path-relative entry names.	766	two array-refs with path-relative entry names.
366		767
367	Example:	768	Example:
…		…
374		775
375	Implementation notes.	776	Implementation notes.
376		777
377	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	778	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
378		779
		780	If readdir returns file type information, then this is used directly to
		781	find directories.
		782
379	After reading the directory, the modification time, size etc. of the	783	Otherwise, after reading the directory, the modification time, size etc.
380	directory before and after the readdir is checked, and if they match (and	784	of the directory before and after the readdir is checked, and if they
381	isn't the current time), the link count will be used to decide how many	785	match (and isn't the current time), the link count will be used to decide
382	entries are directories (if >= 2). Otherwise, no knowledge of the number	786	how many entries are directories (if >= 2). Otherwise, no knowledge of the
383	of subdirectories will be assumed.	787	number of subdirectories will be assumed.
384		788
385	Then entries will be sorted into likely directories (everything without	789	Then entries will be sorted into likely directories a non-initial dot
386	a non-initial dot currently) and likely non-directories (everything	790	currently) and likely non-directories (see C<aio_readdirx>). Then every
387	else). Then every entry plus an appended C</.> will be C<stat>'ed,	791	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
388	likely directories first. If that succeeds, it assumes that the entry	792	in order of their inode numbers. If that succeeds, it assumes that the
389	is a directory or a symlink to directory (which will be checked	793	entry is a directory or a symlink to directory (which will be checked
390	seperately). This is often faster than stat'ing the entry itself because	794	seperately). This is often faster than stat'ing the entry itself because
391	filesystems might detect the type of the entry without reading the inode	795	filesystems might detect the type of the entry without reading the inode
392	data (e.g. ext2fs filetype feature).	796	data (e.g. ext2fs filetype feature), even on systems that cannot return
		797	the filetype information on readdir.
393		798
394	If the known number of directories (link count - 2) has been reached, the	799	If the known number of directories (link count - 2) has been reached, the
395	rest of the entries is assumed to be non-directories.	800	rest of the entries is assumed to be non-directories.
396		801
397	This only works with certainty on POSIX (= UNIX) filesystems, which	802	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
401	as those tend to return 0 or 1 as link counts, which disables the	806	as those tend to return 0 or 1 as link counts, which disables the
402	directory counting heuristic.	807	directory counting heuristic.
403		808
404	=cut	809	=cut
405		810
406	sub aio_scandir($$$) {	811	sub aio_scandir($$;$) {
407	my ($path, $maxreq, $cb) = @_;	812	my ($path, $maxreq, $cb) = @_;
408		813
		814	my $pri = aioreq_pri;
		815
409	my $grp = aio_group $cb;	816	my $grp = aio_group $cb;
410		817
411	$maxreq = 6 if $maxreq <= 0;	818	$maxreq = 4 if $maxreq <= 0;
412		819
413	# stat once	820	# stat once
		821	aioreq_pri $pri;
414	add $grp aio_stat $path, sub {	822	add $grp aio_stat $path, sub {
415	return $grp->result () if $_[0];	823	return $grp->result () if $_[0];
416	my $now = time;	824	my $now = time;
417	my $hash1 = join ":", (stat _)[0,1,3,7,9];	825	my $hash1 = join ":", (stat _)[0,1,3,7,9];
418		826
419	# read the directory entries	827	# read the directory entries
		828	aioreq_pri $pri;
420	add $grp aio_readdir $path, sub {	829	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
421	my $entries = shift	830	my $entries = shift
422	or return $grp->result ();	831	or return $grp->result ();
423		832
424	# stat the dir another time	833	# stat the dir another time
		834	aioreq_pri $pri;
425	add $grp aio_stat $path, sub {	835	add $grp aio_stat $path, sub {
426	my $hash2 = join ":", (stat _)[0,1,3,7,9];	836	my $hash2 = join ":", (stat _)[0,1,3,7,9];
427		837
428	my $ndirs;	838	my $ndirs;
429		839
…		…
435	# on non-posix-fs's, we rely on nlink < 2	845	# on non-posix-fs's, we rely on nlink < 2
436	$ndirs = (stat _)[3] - 2	846	$ndirs = (stat _)[3] - 2
437	or return $grp->result ([], $entries);	847	or return $grp->result ([], $entries);
438	}	848	}
439		849
440	# sort into likely dirs and likely nondirs
441	# dirs == files without ".", short entries first
442	$entries = [map $_->[0],
443	sort { $b->[1] cmp $a->[1] }
444	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
445	@$entries];
446
447	my (@dirs, @nondirs);	850	my (@dirs, @nondirs);
448		851
449	my ($statcb, $schedcb);
450	my $nreq = 0;
451
452	my $statgrp = add $grp aio_group;	852	my $statgrp = add $grp aio_group sub {
		853	$grp->result (\@dirs, \@nondirs);
		854	};
453		855
454	$schedcb = sub {	856	limit $statgrp $maxreq;
455	if (@$entries) {	857	feed $statgrp sub {
456	if ($nreq < $maxreq) {	858	return unless @$entries;
457	my $ent = pop @$entries;	859	my $entry = pop @$entries;
		860
		861	aioreq_pri $pri;
		862	add $statgrp aio_stat "$path/$entry/.", sub {
		863	if ($_[0] < 0) {
		864	push @nondirs, $entry;
		865	} else {
		866	# need to check for real directory
		867	aioreq_pri $pri;
		868	add $statgrp aio_lstat "$path/$entry", sub {
		869	if (-d _) {
		870	push @dirs, $entry;
		871
		872	unless (--$ndirs) {
		873	push @nondirs, @$entries;
		874	feed $statgrp;
		875	}
		876	} else {
		877	push @nondirs, $entry;
		878	}
458	$nreq++;	879	}
459	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
460	}	880	}
461	} elsif (!$nreq) {
462	# finished
463	$statgrp->cancel;
464	undef $statcb;
465	undef $schedcb;
466	$grp->result (\@dirs, \@nondirs);
467	}	881	};
468	};	882	};
469	$statcb = sub {
470	my ($status, $entry) = @_;
471
472	if ($status < 0) {
473	$nreq--;
474	push @nondirs, $entry;
475	&$schedcb;
476	} else {
477	# need to check for real directory
478	add $grp aio_lstat "$path/$entry", sub {
479	$nreq--;
480
481	if (-d _) {
482	push @dirs, $entry;
483
484	if (!--$ndirs) {
485	push @nondirs, @$entries;
486	$entries = [];
487	}
488	} else {
489	push @nondirs, $entry;
490	}
491
492	&$schedcb;
493	}
494	}
495	};
496
497	&$schedcb while @$entries && $nreq < $maxreq;
498	};	883	};
499	};	884	};
500	};	885	};
501		886
502	$grp	887	$grp
503	}	888	}
504		889
		890	=item aio_rmtree $path, $callback->($status)
		891
		892	Delete a directory tree starting (and including) C<$path>, return the
		893	status of the final C<rmdir> only. This is a composite request that
		894	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		895	everything else.
		896
		897	=cut
		898
		899	sub aio_rmtree;
		900	sub aio_rmtree($;$) {
		901	my ($path, $cb) = @_;
		902
		903	my $pri = aioreq_pri;
		904	my $grp = aio_group $cb;
		905
		906	aioreq_pri $pri;
		907	add $grp aio_scandir $path, 0, sub {
		908	my ($dirs, $nondirs) = @_;
		909
		910	my $dirgrp = aio_group sub {
		911	add $grp aio_rmdir $path, sub {
		912	$grp->result ($_[0]);
		913	};
		914	};
		915
		916	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		917	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		918
		919	add $grp $dirgrp;
		920	};
		921
		922	$grp
		923	}
		924
		925	=item aio_sync $callback->($status)
		926
		927	Asynchronously call sync and call the callback when finished.
		928
505	=item aio_fsync $fh, $callback->($status)	929	=item aio_fsync $fh, $callback->($status)
506		930
507	Asynchronously call fsync on the given filehandle and call the callback	931	Asynchronously call fsync on the given filehandle and call the callback
508	with the fsync result code.	932	with the fsync result code.
509		933
…		…
513	callback with the fdatasync result code.	937	callback with the fdatasync result code.
514		938
515	If this call isn't available because your OS lacks it or it couldn't be	939	If this call isn't available because your OS lacks it or it couldn't be
516	detected, it will be emulated by calling C<fsync> instead.	940	detected, it will be emulated by calling C<fsync> instead.
517		941
		942	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		943
		944	Sync the data portion of the file specified by C<$offset> and C<$length>
		945	to disk (but NOT the metadata), by calling the Linux-specific
		946	sync_file_range call. If sync_file_range is not available or it returns
		947	ENOSYS, then fdatasync or fsync is being substituted.
		948
		949	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		950	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		951	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		952	manpage for details.
		953
		954	=item aio_pathsync $path, $callback->($status)
		955
		956	This request tries to open, fsync and close the given path. This is a
		957	composite request intended to sync directories after directory operations
		958	(E.g. rename). This might not work on all operating systems or have any
		959	specific effect, but usually it makes sure that directory changes get
		960	written to disc. It works for anything that can be opened for read-only,
		961	not just directories.
		962
		963	Passes C<0> when everything went ok, and C<-1> on error.
		964
		965	=cut
		966
		967	sub aio_pathsync($;$) {
		968	my ($path, $cb) = @_;
		969
		970	my $pri = aioreq_pri;
		971	my $grp = aio_group $cb;
		972
		973	aioreq_pri $pri;
		974	add $grp aio_open $path, O_RDONLY, 0, sub {
		975	my ($fh) = @_;
		976	if ($fh) {
		977	aioreq_pri $pri;
		978	add $grp aio_fsync $fh, sub {
		979	$grp->result ($_[0]);
		980
		981	aioreq_pri $pri;
		982	add $grp aio_close $fh;
		983	};
		984	} else {
		985	$grp->result (-1);
		986	}
		987	};
		988
		989	$grp
		990	}
		991
518	=item aio_group $callback->(...)	992	=item aio_group $callback->(...)
519
520	[EXPERIMENTAL]
521		993
522	This is a very special aio request: Instead of doing something, it is a	994	This is a very special aio request: Instead of doing something, it is a
523	container for other aio requests, which is useful if you want to bundle	995	container for other aio requests, which is useful if you want to bundle
524	many requests into a single, composite, request.	996	many requests into a single, composite, request with a definite callback
		997	and the ability to cancel the whole request with its subrequests.
525		998
526	Returns an object of class L<IO::AIO::GRP>. See its documentation below	999	Returns an object of class L<IO::AIO::GRP>. See its documentation below
527	for more info.	1000	for more info.
528		1001
529	Example:	1002	Example:
…		…
548	phase and still requires a worker thread. Thus, the callback will not	1021	phase and still requires a worker thread. Thus, the callback will not
549	be executed immediately but only after other requests in the queue have	1022	be executed immediately but only after other requests in the queue have
550	entered their execution phase. This can be used to measure request	1023	entered their execution phase. This can be used to measure request
551	latency.	1024	latency.
552		1025
553	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() *NOT EXPORTED*	1026	=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED*
554		1027
555	Mainly used for debugging and benchmarking, this aio request puts one of	1028	Mainly used for debugging and benchmarking, this aio request puts one of
556	the request workers to sleep for the given time.	1029	the request workers to sleep for the given time.
557		1030
558	While it is theoretically handy to have simple I/O scheduling requests	1031	While it is theoretically handy to have simple I/O scheduling requests
559	like sleep and file handle readable/writable, the overhead this creates	1032	like sleep and file handle readable/writable, the overhead this creates is
560	is immense, so do not use this function except to put your application	1033	immense (it blocks a thread for a long time) so do not use this function
561	under artificial I/O pressure.	1034	except to put your application under artificial I/O pressure.
562		1035
563	=back	1036	=back
564		1037
565	=head2 IO::AIO::REQ CLASS	1038	=head2 IO::AIO::REQ CLASS
566		1039
567	All non-aggregate C<aio_*> functions return an object of this class when	1040	All non-aggregate C<aio_*> functions return an object of this class when
568	called in non-void context.	1041	called in non-void context.
569
570	A request always moves through the following five states in its lifetime,
571	in order: B<ready> (request has been created, but has not been executed
572	yet), B<execute> (request is currently being executed), B<pending>
573	(request has been executed but callback has not been called yet),
574	B<result> (results are being processed synchronously, includes calling the
575	callback) and B<done> (request has reached the end of its lifetime and
576	holds no resources anymore).
577		1042
578	=over 4	1043	=over 4
579		1044
580	=item cancel $req	1045	=item cancel $req
581		1046
…		…
635	=item * They can also can also be added to other IO::AIO::GRP objects.	1100	=item * They can also can also be added to other IO::AIO::GRP objects.
636		1101
637	=item * You must not add requests to a group from within the group callback (or	1102	=item * You must not add requests to a group from within the group callback (or
638	any later time).	1103	any later time).
639		1104
640	=item * This does not harmonise well with C<max_outstanding>, so best do
641	not combine C<aio_group> with it. Groups and feeders are recommended for
642	this kind of concurrency-limiting.
643
644	=back	1105	=back
645		1106
646	Their lifetime, simplified, looks like this: when they are empty, they	1107	Their lifetime, simplified, looks like this: when they are empty, they
647	will finish very quickly. If they contain only requests that are in the	1108	will finish very quickly. If they contain only requests that are in the
648	C<done> state, they will also finish. Otherwise they will continue to	1109	C<done> state, they will also finish. Otherwise they will continue to
649	exist.	1110	exist.
650		1111
651	That means after creating a group you have some time to add requests. And	1112	That means after creating a group you have some time to add requests
652	in the callbacks of those requests, you can add further requests to the	1113	(precisely before the callback has been invoked, which is only done within
653	group. And only when all those requests have finished will the the group	1114	the C<poll_cb>). And in the callbacks of those requests, you can add
654	itself finish.	1115	further requests to the group. And only when all those requests have
		1116	finished will the the group itself finish.
655		1117
656	=over 4	1118	=over 4
657		1119
658	=item add $grp ...	1120	=item add $grp ...
659		1121
…		…
663	be added, including other groups, as long as you do not create circular	1125	be added, including other groups, as long as you do not create circular
664	dependencies.	1126	dependencies.
665		1127
666	Returns all its arguments.	1128	Returns all its arguments.
667		1129
		1130	=item $grp->cancel_subs
		1131
		1132	Cancel all subrequests and clears any feeder, but not the group request
		1133	itself. Useful when you queued a lot of events but got a result early.
		1134
668	=item $grp->result (...)	1135	=item $grp->result (...)
669		1136
670	Set the result value(s) that will be passed to the group callback when all	1137	Set the result value(s) that will be passed to the group callback when all
671	subrequests have finished. By default, no argument will be passed.	1138	subrequests have finished and set the groups errno to the current value
		1139	of errno (just like calling C<errno> without an error number). By default,
		1140	no argument will be passed and errno is zero.
		1141
		1142	=item $grp->errno ([$errno])
		1143
		1144	Sets the group errno value to C<$errno>, or the current value of errno
		1145	when the argument is missing.
		1146
		1147	Every aio request has an associated errno value that is restored when
		1148	the callback is invoked. This method lets you change this value from its
		1149	default (0).
		1150
		1151	Calling C<result> will also set errno, so make sure you either set C<$!>
		1152	before the call to C<result>, or call c<errno> after it.
672		1153
673	=item feed $grp $callback->($grp)	1154	=item feed $grp $callback->($grp)
674
675	[VERY EXPERIMENTAL]
676		1155
677	Sets a feeder/generator on this group: every group can have an attached	1156	Sets a feeder/generator on this group: every group can have an attached
678	generator that generates requests if idle. The idea behind this is that,	1157	generator that generates requests if idle. The idea behind this is that,
679	although you could just queue as many requests as you want in a group,	1158	although you could just queue as many requests as you want in a group,
680	this might starve other requests for a potentially long time. For	1159	this might starve other requests for a potentially long time. For example,
681	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1160	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
682	requests, delaying any later requests for a long time.	1161	delaying any later requests for a long time.
683		1162
684	To avoid this, and allow incremental generation of requests, you can	1163	To avoid this, and allow incremental generation of requests, you can
685	instead a group and set a feeder on it that generates those requests. The	1164	instead a group and set a feeder on it that generates those requests. The
686	feed callback will be called whenever there are few enough (see C<feed_limit>,	1165	feed callback will be called whenever there are few enough (see C<limit>,
687	below) requests active in the group itself and is expected to queue more	1166	below) requests active in the group itself and is expected to queue more
688	requests.	1167	requests.
689		1168
690	The feed can queue as many requests as it likes (i.e. C<add> does not	1169	The feed callback can queue as many requests as it likes (i.e. C<add> does
691	impose any limits).	1170	not impose any limits).
692		1171
693	If the feed does not queue more requests when called, it will be	1172	If the feed does not queue more requests when called, it will be
694	automatically removed from the group.	1173	automatically removed from the group.
695		1174
696	If the feed limit is C<0>, it will be set to C<2> automatically.	1175	If the feed limit is C<0> when this method is called, it will be set to
		1176	C<2> automatically.
697		1177
698	Example:	1178	Example:
699		1179
700	# stat all files in @files, but only ever use four aio requests concurrently:	1180	# stat all files in @files, but only ever use four aio requests concurrently:
701		1181
702	my $grp = aio_group sub { print "finished\n" };	1182	my $grp = aio_group sub { print "finished\n" };
703	feed_limit $grp 4;	1183	limit $grp 4;
704	feed $grp sub {	1184	feed $grp sub {
705	my $file = pop @files	1185	my $file = pop @files
706	or return;	1186	or return;
707		1187
708	add $grp aio_stat $file, sub { ... };	1188	add $grp aio_stat $file, sub { ... };
709	};	1189	};
710		1190
711	=item feed_limit $grp $num	1191	=item limit $grp $num
712		1192
713	Sets the feeder limit for the group: The feeder will be called whenever	1193	Sets the feeder limit for the group: The feeder will be called whenever
714	the group contains less than this many requests.	1194	the group contains less than this many requests.
715		1195
716	Setting the limit to C<0> will pause the feeding process.	1196	Setting the limit to C<0> will pause the feeding process.
717		1197
		1198	The default value for the limit is C<0>, but note that setting a feeder
		1199	automatically bumps it up to C<2>.
		1200
718	=back	1201	=back
719		1202
720	=head2 SUPPORT FUNCTIONS	1203	=head2 SUPPORT FUNCTIONS
		1204
		1205	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
721		1206
722	=over 4	1207	=over 4
723		1208
724	=item $fileno = IO::AIO::poll_fileno	1209	=item $fileno = IO::AIO::poll_fileno
725		1210
…		…
730		1215
731	See C<poll_cb> for an example.	1216	See C<poll_cb> for an example.
732		1217
733	=item IO::AIO::poll_cb	1218	=item IO::AIO::poll_cb
734		1219
735	Process all outstanding events on the result pipe. You have to call this	1220	Process some outstanding events on the result pipe. You have to call this
736	regularly. Returns the number of events processed. Returns immediately	1221	regularly. Returns C<0> if all events could be processed, or C<-1> if it
737	when no events are outstanding.	1222	returned earlier for whatever reason. Returns immediately when no events
		1223	are outstanding. The amount of events processed depends on the settings of
		1224	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1225
		1226	If not all requests were processed for whatever reason, the filehandle
		1227	will still be ready when C<poll_cb> returns, so normally you don't have to
		1228	do anything special to have it called later.
738		1229
739	Example: Install an Event watcher that automatically calls	1230	Example: Install an Event watcher that automatically calls
740	IO::AIO::poll_cb with high priority:	1231	IO::AIO::poll_cb with high priority:
741		1232
742	Event->io (fd => IO::AIO::poll_fileno,	1233	Event->io (fd => IO::AIO::poll_fileno,
743	poll => 'r', async => 1,	1234	poll => 'r', async => 1,
744	cb => \&IO::AIO::poll_cb);	1235	cb => \&IO::AIO::poll_cb);
745		1236
		1237	=item IO::AIO::max_poll_reqs $nreqs
		1238
		1239	=item IO::AIO::max_poll_time $seconds
		1240
		1241	These set the maximum number of requests (default C<0>, meaning infinity)
		1242	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1243	the maximum amount of time (default C<0>, meaning infinity) spent in
		1244	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1245	of time C<poll_cb> is allowed to use).
		1246
		1247	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1248	syscall per request processed, which is not normally a problem unless your
		1249	callbacks are really really fast or your OS is really really slow (I am
		1250	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1251
		1252	Setting these is useful if you want to ensure some level of
		1253	interactiveness when perl is not fast enough to process all requests in
		1254	time.
		1255
		1256	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1257
		1258	Example: Install an Event watcher that automatically calls
		1259	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1260	program get the CPU sometimes even under high AIO load.
		1261
		1262	# try not to spend much more than 0.1s in poll_cb
		1263	IO::AIO::max_poll_time 0.1;
		1264
		1265	# use a low priority so other tasks have priority
		1266	Event->io (fd => IO::AIO::poll_fileno,
		1267	poll => 'r', nice => 1,
		1268	cb => &IO::AIO::poll_cb);
		1269
746	=item IO::AIO::poll_wait	1270	=item IO::AIO::poll_wait
747		1271
		1272	If there are any outstanding requests and none of them in the result
748	Wait till the result filehandle becomes ready for reading (simply does a	1273	phase, wait till the result filehandle becomes ready for reading (simply
749	C<select> on the filehandle. This is useful if you want to synchronously wait	1274	does a C<select> on the filehandle. This is useful if you want to
750	for some requests to finish).	1275	synchronously wait for some requests to finish).
751		1276
752	See C<nreqs> for an example.	1277	See C<nreqs> for an example.
753		1278
		1279	=item IO::AIO::poll
		1280
		1281	Waits until some requests have been handled.
		1282
		1283	Returns the number of requests processed, but is otherwise strictly
		1284	equivalent to:
		1285
		1286	IO::AIO::poll_wait, IO::AIO::poll_cb
		1287
754	=item IO::AIO::nreqs	1288	=item IO::AIO::flush
755		1289
756	Returns the number of requests currently outstanding (i.e. for which their	1290	Wait till all outstanding AIO requests have been handled.
757	callback has not been invoked yet).
758		1291
759	Example: wait till there are no outstanding requests anymore:	1292	Strictly equivalent to:
760		1293
761	IO::AIO::poll_wait, IO::AIO::poll_cb	1294	IO::AIO::poll_wait, IO::AIO::poll_cb
762	while IO::AIO::nreqs;	1295	while IO::AIO::nreqs;
763		1296
764	=item IO::AIO::flush	1297	=back
765		1298
766	Wait till all outstanding AIO requests have been handled.	1299	=head3 CONTROLLING THE NUMBER OF THREADS
767		1300
768	Strictly equivalent to:	1301	=over
769
770	IO::AIO::poll_wait, IO::AIO::poll_cb
771	while IO::AIO::nreqs;
772
773	=item IO::AIO::poll
774
775	Waits until some requests have been handled.
776
777	Strictly equivalent to:
778
779	IO::AIO::poll_wait, IO::AIO::poll_cb
780	if IO::AIO::nreqs;
781		1302
782	=item IO::AIO::min_parallel $nthreads	1303	=item IO::AIO::min_parallel $nthreads
783		1304
784	Set the minimum number of AIO threads to C<$nthreads>. The current	1305	Set the minimum number of AIO threads to C<$nthreads>. The current
785	default is C<8>, which means eight asynchronous operations can execute	1306	default is C<8>, which means eight asynchronous operations can execute
786	concurrently at any one time (the number of outstanding requests,	1307	concurrently at any one time (the number of outstanding requests,
787	however, is unlimited).	1308	however, is unlimited).
788		1309
789	IO::AIO starts threads only on demand, when an AIO request is queued and	1310	IO::AIO starts threads only on demand, when an AIO request is queued and
790	no free thread exists.	1311	no free thread exists. Please note that queueing up a hundred requests can
		1312	create demand for a hundred threads, even if it turns out that everything
		1313	is in the cache and could have been processed faster by a single thread.
791		1314
792	It is recommended to keep the number of threads relatively low, as some	1315	It is recommended to keep the number of threads relatively low, as some
793	Linux kernel versions will scale negatively with the number of threads	1316	Linux kernel versions will scale negatively with the number of threads
794	(higher parallelity => MUCH higher latency). With current Linux 2.6	1317	(higher parallelity => MUCH higher latency). With current Linux 2.6
795	versions, 4-32 threads should be fine.	1318	versions, 4-32 threads should be fine.
…		…
809	This module automatically runs C<max_parallel 0> at program end, to ensure	1332	This module automatically runs C<max_parallel 0> at program end, to ensure
810	that all threads are killed and that there are no outstanding requests.	1333	that all threads are killed and that there are no outstanding requests.
811		1334
812	Under normal circumstances you don't need to call this function.	1335	Under normal circumstances you don't need to call this function.
813		1336
		1337	=item IO::AIO::max_idle $nthreads
		1338
		1339	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1340	threads that did not get a request to process within 10 seconds). That
		1341	means if a thread becomes idle while C<$nthreads> other threads are also
		1342	idle, it will free its resources and exit.
		1343
		1344	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1345	to allow for extremely high load situations, but want to free resources
		1346	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1347
		1348	The default is probably ok in most situations, especially if thread
		1349	creation is fast. If thread creation is very slow on your system you might
		1350	want to use larger values.
		1351
814	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1352	=item IO::AIO::max_outstanding $maxreqs
815		1353
816	[DEPRECATED]	1354	This is a very bad function to use in interactive programs because it
		1355	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1356	use an C<aio_group> together with a feed callback.
817		1357
818	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1358	Sets the maximum number of outstanding requests to C<$nreqs>. If you
819	try to queue up more than this number of requests, the caller will block until	1359	do queue up more than this number of requests, the next call to the
820	some requests have been handled.	1360	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1361	function will block until the limit is no longer exceeded.
821		1362
822	The default is very large, so normally there is no practical limit. If you	1363	The default value is very large, so there is no practical limit on the
823	queue up many requests in a loop it often improves speed if you set	1364	number of outstanding requests.
824	this to a relatively low number, such as C<100>.
825		1365
826	This function does not work well together with C<aio_group>'s, and their	1366	You can still queue as many requests as you want. Therefore,
827	feeder interface is better suited to limiting concurrency, so do not use	1367	C<max_outstanding> is mainly useful in simple scripts (with low values) or
828	this function.	1368	as a stop gap to shield against fatal memory overflow (with large values).
829
830	Under normal circumstances you don't need to call this function.
831		1369
832	=back	1370	=back
833		1371
		1372	=head3 STATISTICAL INFORMATION
		1373
		1374	=over
		1375
		1376	=item IO::AIO::nreqs
		1377
		1378	Returns the number of requests currently in the ready, execute or pending
		1379	states (i.e. for which their callback has not been invoked yet).
		1380
		1381	Example: wait till there are no outstanding requests anymore:
		1382
		1383	IO::AIO::poll_wait, IO::AIO::poll_cb
		1384	while IO::AIO::nreqs;
		1385
		1386	=item IO::AIO::nready
		1387
		1388	Returns the number of requests currently in the ready state (not yet
		1389	executed).
		1390
		1391	=item IO::AIO::npending
		1392
		1393	Returns the number of requests currently in the pending state (executed,
		1394	but not yet processed by poll_cb).
		1395
		1396	=back
		1397
834	=cut	1398	=cut
835		1399
836	# support function to convert a fd into a perl filehandle
837	sub _fd2fh {
838	return undef if $_[0] < 0;
839
840	# try to generate nice filehandles
841	my $sym = "IO::AIO::fd#$_[0]";
842	local *$sym;
843
844	open *$sym, "+<&=$_[0]" # usually works under any unix
845	or open *$sym, "<&=$_[0]" # cygwin needs this
846	or open *$sym, ">&=$_[0]" # or this
847	or return undef;
848
849	*$sym
850	}
851
852	min_parallel 8;	1400	min_parallel 8;
853		1401
854	END {	1402	END { flush }
855	max_parallel 0;
856	}
857		1403
858	1;	1404	1;
859		1405
860	=head2 FORK BEHAVIOUR	1406	=head2 FORK BEHAVIOUR
861		1407
862	This module should do "the right thing" when the process using it forks:	1408	This module should do "the right thing" when the process using it forks:
863		1409
864	Before the fork, IO::AIO enters a quiescent state where no requests	1410	Before the fork, IO::AIO enters a quiescent state where no requests
865	can be added in other threads and no results will be processed. After	1411	can be added in other threads and no results will be processed. After
866	the fork the parent simply leaves the quiescent state and continues	1412	the fork the parent simply leaves the quiescent state and continues
867	request/result processing, while the child clears the request/result	1413	request/result processing, while the child frees the request/result queue
868	queue (so the requests started before the fork will only be handled in	1414	(so that the requests started before the fork will only be handled in the
869	the parent). Threads will be started on demand until the limit ste in the	1415	parent). Threads will be started on demand until the limit set in the
870	parent process has been reached again.	1416	parent process has been reached again.
871		1417
872	In short: the parent will, after a short pause, continue as if fork had	1418	In short: the parent will, after a short pause, continue as if fork had
873	not been called, while the child will act as if IO::AIO has not been used	1419	not been called, while the child will act as if IO::AIO has not been used
874	yet.	1420	yet.
875		1421
876	=head2 MEMORY USAGE	1422	=head2 MEMORY USAGE
877		1423
		1424	Per-request usage:
		1425
878	Each aio request uses - depending on your architecture - around 128 bytes	1426	Each aio request uses - depending on your architecture - around 100-200
879	of memory. In addition, stat requests need a stat buffer (possibly a few	1427	bytes of memory. In addition, stat requests need a stat buffer (possibly
880	hundred bytes). Perl scalars and other data passed into aio requests will	1428	a few hundred bytes), readdir requires a result buffer and so on. Perl
881	also be locked.	1429	scalars and other data passed into aio requests will also be locked and
		1430	will consume memory till the request has entered the done state.
882		1431
883	This is now awfully much, so queuing lots of requests is not usually a	1432	This is not awfully much, so queuing lots of requests is not usually a
884	problem.	1433	problem.
885		1434
886	Each thread needs a stack area which is usually around 16k, sometimes much	1435	Per-thread usage:
887	larger, depending on the OS.	1436
		1437	In the execution phase, some aio requests require more memory for
		1438	temporary buffers, and each thread requires a stack and other data
		1439	structures (usually around 16k-128k, depending on the OS).
		1440
		1441	=head1 KNOWN BUGS
		1442
		1443	Known bugs will be fixed in the next release.
888		1444
889	=head1 SEE ALSO	1445	=head1 SEE ALSO
890		1446
891	L<Coro>, L<Linux::AIO> (obsolete).	1447	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1448	more natural syntax.
892		1449
893	=head1 AUTHOR	1450	=head1 AUTHOR
894		1451
895	Marc Lehmann <schmorp@schmorp.de>	1452	Marc Lehmann <schmorp@schmorp.de>
896	http://home.schmorp.de/	1453	http://home.schmorp.de/

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