[ViewVC] Diff of: cvs/IO-AIO/AIO.pm

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.51 by root, Sat Jun 24 19:14:04 2006 UTC vs.
Revision 1.116 by root, Wed Oct 3 21:27:51 2007 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
16	aio_read $fh, 30000, 1024, $buffer, 0, sub {	17	aio_read $fh, 30000, 1024, $buffer, 0, sub {
17	$_[0] > 0 or die "read error: $!";	18	$_[0] > 0 or die "read error: $!";
18	};	19	};
19		20
20	# AnyEvent	21	# version 2+ has request and group objects
		22	use IO::AIO 2;
		23
		24	aioreq_pri 4; # give next request a very high priority
		25	my $req = aio_unlink "/tmp/file", sub { };
		26	$req->cancel; # cancel request if still in queue
		27
		28	my $grp = aio_group sub { print "all stats done\n" };
		29	add $grp aio_stat "..." for ...;
		30
		31	# AnyEvent integration
21	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	32	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
22	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });	33	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
23		34
24	# Event	35	# Event integration
25	Event->io (fd => IO::AIO::poll_fileno,	36	Event->io (fd => IO::AIO::poll_fileno,
26	poll => 'r',	37	poll => 'r',
27	cb => \&IO::AIO::poll_cb);	38	cb => \&IO::AIO::poll_cb);
28		39
29	# Glib/Gtk2	40	# Glib/Gtk2 integration
30	add_watch Glib::IO IO::AIO::poll_fileno,	41	add_watch Glib::IO IO::AIO::poll_fileno,
31	in => sub { IO::AIO::poll_cb; 1 };	42	in => sub { IO::AIO::poll_cb; 1 };
32		43
33	# Tk	44	# Tk integration
34	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",	45	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
35	readable => \&IO::AIO::poll_cb);	46	readable => \&IO::AIO::poll_cb);
36		47
37	# Danga::Socket	48	# Danga::Socket integration
38	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	49	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
39	\&IO::AIO::poll_cb);	50	\&IO::AIO::poll_cb);
40		51
41
42	=head1 DESCRIPTION	52	=head1 DESCRIPTION
43		53
44	This module implements asynchronous I/O using whatever means your	54	This module implements asynchronous I/O using whatever means your
45	operating system supports.	55	operating system supports.
46		56
		57	Asynchronous means that operations that can normally block your program
		58	(e.g. reading from disk) will be done asynchronously: the operation
		59	will still block, but you can do something else in the meantime. This
		60	is extremely useful for programs that need to stay interactive even
		61	when doing heavy I/O (GUI programs, high performance network servers
		62	etc.), but can also be used to easily do operations in parallel that are
		63	normally done sequentially, e.g. stat'ing many files, which is much faster
		64	on a RAID volume or over NFS when you do a number of stat operations
		65	concurrently.
		66
		67	While most of this works on all types of file descriptors (for
		68	example sockets), using these functions on file descriptors that
		69	support nonblocking operation (again, sockets, pipes etc.) is very
		70	inefficient. Use an event loop for that (such as the L<Event\|Event>
		71	module): IO::AIO will naturally fit into such an event loop itself.
		72
47	Currently, a number of threads are started that execute your read/writes	73	In this version, a number of threads are started that execute your
48	and signal their completion. You don't need thread support in your libc or	74	requests and signal their completion. You don't need thread support
49	perl, and the threads created by this module will not be visible to the	75	in perl, and the threads created by this module will not be visible
50	pthreads library. In the future, this module might make use of the native	76	to perl. In the future, this module might make use of the native aio
51	aio functions available on many operating systems. However, they are often	77	functions available on many operating systems. However, they are often
52	not well-supported (Linux doesn't allow them on normal files currently,	78	not well-supported or restricted (GNU/Linux doesn't allow them on normal
53	for example), and they would only support aio_read and aio_write, so the	79	files currently, for example), and they would only support aio_read and
54	remaining functionality would have to be implemented using threads anyway.	80	aio_write, so the remaining functionality would have to be implemented
		81	using threads anyway.
55		82
56	Although the module will work with in the presence of other threads, it is	83	Although the module will work in the presence of other (Perl-) threads,
57	currently not reentrant, so use appropriate locking yourself, always call	84	it is currently not reentrant in any way, so use appropriate locking
58	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	85	yourself, always call C<poll_cb> from within the same thread, or never
59	C<aio_> functions) recursively.	86	call C<poll_cb> (or other C<aio_> functions) recursively.
		87
		88	=head2 EXAMPLE
		89
		90	This is a simple example that uses the Event module and loads
		91	F</etc/passwd> asynchronously:
		92
		93	use Fcntl;
		94	use Event;
		95	use IO::AIO;
		96
		97	# register the IO::AIO callback with Event
		98	Event->io (fd => IO::AIO::poll_fileno,
		99	poll => 'r',
		100	cb => \&IO::AIO::poll_cb);
		101
		102	# queue the request to open /etc/passwd
		103	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		104	my $fh = shift
		105	or die "error while opening: $!";
		106
		107	# stat'ing filehandles is generally non-blocking
		108	my $size = -s $fh;
		109
		110	# queue a request to read the file
		111	my $contents;
		112	aio_read $fh, 0, $size, $contents, 0, sub {
		113	$_[0] == $size
		114	or die "short read: $!";
		115
		116	close $fh;
		117
		118	# file contents now in $contents
		119	print $contents;
		120
		121	# exit event loop and program
		122	Event::unloop;
		123	};
		124	};
		125
		126	# possibly queue up other requests, or open GUI windows,
		127	# check for sockets etc. etc.
		128
		129	# process events as long as there are some:
		130	Event::loop;
		131
		132	=head1 REQUEST ANATOMY AND LIFETIME
		133
		134	Every C<aio_*> function creates a request. which is a C data structure not
		135	directly visible to Perl.
		136
		137	If called in non-void context, every request function returns a Perl
		138	object representing the request. In void context, nothing is returned,
		139	which saves a bit of memory.
		140
		141	The perl object is a fairly standard ref-to-hash object. The hash contents
		142	are not used by IO::AIO so you are free to store anything you like in it.
		143
		144	During their existance, aio requests travel through the following states,
		145	in order:
		146
		147	=over 4
		148
		149	=item ready
		150
		151	Immediately after a request is created it is put into the ready state,
		152	waiting for a thread to execute it.
		153
		154	=item execute
		155
		156	A thread has accepted the request for processing and is currently
		157	executing it (e.g. blocking in read).
		158
		159	=item pending
		160
		161	The request has been executed and is waiting for result processing.
		162
		163	While request submission and execution is fully asynchronous, result
		164	processing is not and relies on the perl interpreter calling C<poll_cb>
		165	(or another function with the same effect).
		166
		167	=item result
		168
		169	The request results are processed synchronously by C<poll_cb>.
		170
		171	The C<poll_cb> function will process all outstanding aio requests by
		172	calling their callbacks, freeing memory associated with them and managing
		173	any groups they are contained in.
		174
		175	=item done
		176
		177	Request has reached the end of its lifetime and holds no resources anymore
		178	(except possibly for the Perl object, but its connection to the actual
		179	aio request is severed and calling its methods will either do nothing or
		180	result in a runtime error).
		181
		182	=back
60		183
61	=cut	184	=cut
62		185
63	package IO::AIO;	186	package IO::AIO;
64		187
…		…
66	use strict 'vars';	189	use strict 'vars';
67		190
68	use base 'Exporter';	191	use base 'Exporter';
69		192
70	BEGIN {	193	BEGIN {
71	our $VERSION = '1.8';	194	our $VERSION = '2.5';
72		195
73	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	196	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
74	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	197	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
75	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move);	198	aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
76	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	199	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
		200	aio_chown aio_chmod aio_utime aio_truncate);
		201	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
		202	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		203	min_parallel max_parallel max_idle
		204	nreqs nready npending nthreads
		205	max_poll_time max_poll_reqs);
		206
		207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
77		208
78	require XSLoader;	209	require XSLoader;
79	XSLoader::load ("IO::AIO", $VERSION);	210	XSLoader::load ("IO::AIO", $VERSION);
80	}	211	}
81		212
82	=head1 FUNCTIONS	213	=head1 FUNCTIONS
83		214
84	=head2 AIO FUNCTIONS	215	=head2 AIO REQUEST FUNCTIONS
85		216
86	All the C<aio_*> calls are more or less thin wrappers around the syscall	217	All the C<aio_*> calls are more or less thin wrappers around the syscall
87	with the same name (sans C<aio_>). The arguments are similar or identical,	218	with the same name (sans C<aio_>). The arguments are similar or identical,
88	and they all accept an additional (and optional) C<$callback> argument	219	and they all accept an additional (and optional) C<$callback> argument
89	which must be a code reference. This code reference will get called with	220	which must be a code reference. This code reference will get called with
…		…
92	syscall has been executed asynchronously.	223	syscall has been executed asynchronously.
93		224
94	All functions expecting a filehandle keep a copy of the filehandle	225	All functions expecting a filehandle keep a copy of the filehandle
95	internally until the request has finished.	226	internally until the request has finished.
96		227
		228	All functions return request objects of type L<IO::AIO::REQ> that allow
		229	further manipulation of those requests while they are in-flight.
		230
97	The pathnames you pass to these routines I<must> be absolute and	231	The pathnames you pass to these routines I<must> be absolute and
98	encoded in byte form. The reason for the former is that at the time the	232	encoded as octets. The reason for the former is that at the time the
99	request is being executed, the current working directory could have	233	request is being executed, the current working directory could have
100	changed. Alternatively, you can make sure that you never change the	234	changed. Alternatively, you can make sure that you never change the
101	current working directory.	235	current working directory anywhere in the program and then use relative
		236	paths.
102		237
103	To encode pathnames to byte form, either make sure you either: a)	238	To encode pathnames as octets, either make sure you either: a) always pass
104	always pass in filenames you got from outside (command line, readdir	239	in filenames you got from outside (command line, readdir etc.) without
105	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	240	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
106	your pathnames to the locale (or other) encoding in effect in the user	241	your pathnames to the locale (or other) encoding in effect in the user
107	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	242	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
108	use something else.	243	use something else to ensure your scalar has the correct contents.
		244
		245	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		246	handles correctly wether it is set or not.
109		247
110	=over 4	248	=over 4
		249
		250	=item $prev_pri = aioreq_pri [$pri]
		251
		252	Returns the priority value that would be used for the next request and, if
		253	C<$pri> is given, sets the priority for the next aio request.
		254
		255	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		256	and C<4>, respectively. Requests with higher priority will be serviced
		257	first.
		258
		259	The priority will be reset to C<0> after each call to one of the C<aio_*>
		260	functions.
		261
		262	Example: open a file with low priority, then read something from it with
		263	higher priority so the read request is serviced before other low priority
		264	open requests (potentially spamming the cache):
		265
		266	aioreq_pri -3;
		267	aio_open ..., sub {
		268	return unless $_[0];
		269
		270	aioreq_pri -2;
		271	aio_read $_[0], ..., sub {
		272	...
		273	};
		274	};
		275
		276
		277	=item aioreq_nice $pri_adjust
		278
		279	Similar to C<aioreq_pri>, but subtracts the given value from the current
		280	priority, so the effect is cumulative.
		281
111		282
112	=item aio_open $pathname, $flags, $mode, $callback->($fh)	283	=item aio_open $pathname, $flags, $mode, $callback->($fh)
113		284
114	Asynchronously open or create a file and call the callback with a newly	285	Asynchronously open or create a file and call the callback with a newly
115	created filehandle for the file.	286	created filehandle for the file.
…		…
121	list. They are the same as used by C<sysopen>.	292	list. They are the same as used by C<sysopen>.
122		293
123	Likewise, C<$mode> specifies the mode of the newly created file, if it	294	Likewise, C<$mode> specifies the mode of the newly created file, if it
124	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	295	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
125	except that it is mandatory (i.e. use C<0> if you don't create new files,	296	except that it is mandatory (i.e. use C<0> if you don't create new files,
126	and C<0666> or C<0777> if you do).	297	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		298	by the umask in effect then the request is being executed, so better never
		299	change the umask.
127		300
128	Example:	301	Example:
129		302
130	aio_open "/etc/passwd", O_RDONLY, 0, sub {	303	aio_open "/etc/passwd", O_RDONLY, 0, sub {
131	if ($_[0]) {	304	if ($_[0]) {
…		…
134	} else {	307	} else {
135	die "open failed: $!\n";	308	die "open failed: $!\n";
136	}	309	}
137	};	310	};
138		311
		312
139	=item aio_close $fh, $callback->($status)	313	=item aio_close $fh, $callback->($status)
140		314
141	Asynchronously close a file and call the callback with the result	315	Asynchronously close a file and call the callback with the result
142	code. I<WARNING:> although accepted, you should not pass in a perl	316	code.
143	filehandle here, as perl will likely close the file descriptor another
144	time when the filehandle is destroyed. Normally, you can safely call perls
145	C<close> or just let filehandles go out of scope.
146		317
147	This is supposed to be a bug in the API, so that might change. It's	318	Unlike the other functions operating on files, this function uses the
148	therefore best to avoid this function.	319	PerlIO layer to close the filehandle. The reason is that the PerlIO API
		320	insists on closing the underlying fd itself, no matter what, and doesn't
		321	allow modifications to the fd. Unfortunately, it is not clear that you can
		322	call PerlIO from different threads (actually, its quite clear that this
		323	won't work in some cases), so while it likely works perfectly with simple
		324	file handles (such as the ones created by C<aio_open>) it might fail in
		325	interesting ways for others.
		326
		327	Having said that, aio_close tries to clean up the filehandle as much as
		328	possible before handing it to an io thread, and generally does work.
		329
149		330
150	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	331	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
151		332
152	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	333	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
153		334
154	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	335	Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>
155	into the scalar given by C<data> and offset C<dataoffset> and calls the	336	into the scalar given by C<$data> and offset C<$dataoffset> and calls the
156	callback without the actual number of bytes read (or -1 on error, just	337	callback without the actual number of bytes read (or -1 on error, just
157	like the syscall).	338	like the syscall).
158		339
		340	If C<$offset> is undefined, then the current file descriptor offset will
		341	be used (and updated), otherwise the file descriptor offset will not be
		342	changed by these calls.
		343
		344	If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
		345
		346	If C<$dataoffset> is less than zero, it will be counted from the end of
		347	C<$data>.
		348
159	The C<$data> scalar I<MUST NOT> be modified in any way while the request	349	The C<$data> scalar I<MUST NOT> be modified in any way while the request
160	is outstanding. Modifying it can result in segfaults or WW3 (if the	350	is outstanding. Modifying it can result in segfaults or World War III (if
161	necessary/optional hardware is installed).	351	the necessary/optional hardware is installed).
162		352
163	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	353	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
164	offset C<0> within the scalar:	354	offset C<0> within the scalar:
165		355
166	aio_read $fh, 7, 15, $buffer, 0, sub {	356	aio_read $fh, 7, 15, $buffer, 0, sub {
167	$_[0] > 0 or die "read error: $!";	357	$_[0] > 0 or die "read error: $!";
168	print "read $_[0] bytes: <$buffer>\n";	358	print "read $_[0] bytes: <$buffer>\n";
169	};	359	};
170		360
171	=item aio_move $srcpath, $dstpath, $callback->($status)
172
173	[EXPERIMENTAL]
174
175	Try to move the I<file> (directories not supported as either source or destination)
176	from C<$srcpath> to C<$dstpath> and call the callback with the C<0> (error) or C<-1> ok.
177
178	This is a composite request that tries to rename(2) the file first. If
179	rename files with C<EXDEV>, it creates the destination file with mode 0200
180	and copies the contents of the source file into it using C<aio_sendfile>,
181	followed by restoring atime, mtime, access mode and uid/gid, in that
182	order, and unlinking the C<$srcpath>.
183
184	If an error occurs, the partial destination file will be unlinked, if
185	possible, except when setting atime, mtime, access mode and uid/gid, where
186	errors are being ignored.
187
188	=cut
189
190	sub aio_move($$$) {
191	my ($src, $dst, $cb) = @_;
192
193	aio_rename $src, $dst, sub {
194	if ($_[0] && $! == EXDEV) {
195	aio_open $src, O_RDONLY, 0, sub {
196	if (my $src_fh = $_[0]) {
197	my @stat = stat $src_fh;
198
199	aio_open $dst, O_WRONLY, 0200, sub {
200	if (my $dst_fh = $_[0]) {
201	aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
202	close $src_fh;
203
204	if ($_[0] == $stat[7]) {
205	utime $stat[8], $stat[9], $dst;
206	chmod $stat[2] & 07777, $dst_fh;
207	chown $stat[4], $stat[5], $dst_fh;
208	close $dst_fh;
209
210	aio_unlink $src, sub {
211	$cb->($_[0]);
212	};
213	} else {
214	my $errno = $!;
215	aio_unlink $dst, sub {
216	$! = $errno;
217	$cb->(-1);
218	};
219	}
220	};
221	} else {
222	$cb->(-1);
223	}
224	},
225
226	} else {
227	$cb->(-1);
228	}
229	};
230	} else {
231	$cb->($_[0]);
232	}
233	};
234	}
235		361
236	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	362	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
237		363
238	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	364	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
239	reading at byte offset C<$in_offset>, and starts writing at the current	365	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
253	C<$in_fh> than are written, and there is no way to find out how many	379	C<$in_fh> than are written, and there is no way to find out how many
254	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	380	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
255	provides the number of bytes written to C<$out_fh>. Only if the result	381	provides the number of bytes written to C<$out_fh>. Only if the result
256	value equals C<$length> one can assume that C<$length> bytes have been	382	value equals C<$length> one can assume that C<$length> bytes have been
257	read.	383	read.
		384
258		385
259	=item aio_readahead $fh,$offset,$length, $callback->($retval)	386	=item aio_readahead $fh,$offset,$length, $callback->($retval)
260		387
261	C<aio_readahead> populates the page cache with data from a file so that	388	C<aio_readahead> populates the page cache with data from a file so that
262	subsequent reads from that file will not block on disk I/O. The C<$offset>	389	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
268	file. The current file offset of the file is left unchanged.	395	file. The current file offset of the file is left unchanged.
269		396
270	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	397	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
271	emulated by simply reading the data, which would have a similar effect.	398	emulated by simply reading the data, which would have a similar effect.
272		399
		400
273	=item aio_stat $fh_or_path, $callback->($status)	401	=item aio_stat $fh_or_path, $callback->($status)
274		402
275	=item aio_lstat $fh, $callback->($status)	403	=item aio_lstat $fh, $callback->($status)
276		404
277	Works like perl's C<stat> or C<lstat> in void context. The callback will	405	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
290	aio_stat "/etc/passwd", sub {	418	aio_stat "/etc/passwd", sub {
291	$_[0] and die "stat failed: $!";	419	$_[0] and die "stat failed: $!";
292	print "size is ", -s _, "\n";	420	print "size is ", -s _, "\n";
293	};	421	};
294		422
		423
		424	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		425
		426	Works like perl's C<utime> function (including the special case of $atime
		427	and $mtime being undef). Fractional times are supported if the underlying
		428	syscalls support them.
		429
		430	When called with a pathname, uses utimes(2) if available, otherwise
		431	utime(2). If called on a file descriptor, uses futimes(2) if available,
		432	otherwise returns ENOSYS, so this is not portable.
		433
		434	Examples:
		435
		436	# set atime and mtime to current time (basically touch(1)):
		437	aio_utime "path", undef, undef;
		438	# set atime to current time and mtime to beginning of the epoch:
		439	aio_utime "path", time, undef; # undef==0
		440
		441
		442	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		443
		444	Works like perl's C<chown> function, except that C<undef> for either $uid
		445	or $gid is being interpreted as "do not change" (but -1 can also be used).
		446
		447	Examples:
		448
		449	# same as "chown root path" in the shell:
		450	aio_chown "path", 0, -1;
		451	# same as above:
		452	aio_chown "path", 0, undef;
		453
		454
		455	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		456
		457	Works like truncate(2) or ftruncate(2).
		458
		459
		460	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		461
		462	Works like perl's C<chmod> function.
		463
		464
295	=item aio_unlink $pathname, $callback->($status)	465	=item aio_unlink $pathname, $callback->($status)
296		466
297	Asynchronously unlink (delete) a file and call the callback with the	467	Asynchronously unlink (delete) a file and call the callback with the
298	result code.	468	result code.
299		469
		470
		471	=item aio_mknod $path, $mode, $dev, $callback->($status)
		472
		473	[EXPERIMENTAL]
		474
		475	Asynchronously create a device node (or fifo). See mknod(2).
		476
		477	The only (POSIX-) portable way of calling this function is:
		478
		479	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		480
		481
300	=item aio_link $srcpath, $dstpath, $callback->($status)	482	=item aio_link $srcpath, $dstpath, $callback->($status)
301		483
302	Asynchronously create a new link to the existing object at C<$srcpath> at	484	Asynchronously create a new link to the existing object at C<$srcpath> at
303	the path C<$dstpath> and call the callback with the result code.	485	the path C<$dstpath> and call the callback with the result code.
304		486
		487
305	=item aio_symlink $srcpath, $dstpath, $callback->($status)	488	=item aio_symlink $srcpath, $dstpath, $callback->($status)
306		489
307	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	490	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
308	the path C<$dstpath> and call the callback with the result code.	491	the path C<$dstpath> and call the callback with the result code.
309		492
		493
		494	=item aio_readlink $path, $callback->($link)
		495
		496	Asynchronously read the symlink specified by C<$path> and pass it to
		497	the callback. If an error occurs, nothing or undef gets passed to the
		498	callback.
		499
		500
310	=item aio_rename $srcpath, $dstpath, $callback->($status)	501	=item aio_rename $srcpath, $dstpath, $callback->($status)
311		502
312	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	503	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
313	rename(2) and call the callback with the result code.	504	rename(2) and call the callback with the result code.
314		505
		506
		507	=item aio_mkdir $pathname, $mode, $callback->($status)
		508
		509	Asynchronously mkdir (create) a directory and call the callback with
		510	the result code. C<$mode> will be modified by the umask at the time the
		511	request is executed, so do not change your umask.
		512
		513
315	=item aio_rmdir $pathname, $callback->($status)	514	=item aio_rmdir $pathname, $callback->($status)
316		515
317	Asynchronously rmdir (delete) a directory and call the callback with the	516	Asynchronously rmdir (delete) a directory and call the callback with the
318	result code.	517	result code.
		518
319		519
320	=item aio_readdir $pathname, $callback->($entries)	520	=item aio_readdir $pathname, $callback->($entries)
321		521
322	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	522	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
323	directory (i.e. opendir + readdir + closedir). The entries will not be	523	directory (i.e. opendir + readdir + closedir). The entries will not be
324	sorted, and will B<NOT> include the C<.> and C<..> entries.	524	sorted, and will B<NOT> include the C<.> and C<..> entries.
325		525
326	The callback a single argument which is either C<undef> or an array-ref	526	The callback a single argument which is either C<undef> or an array-ref
327	with the filenames.	527	with the filenames.
328		528
		529
		530	=item aio_load $path, $data, $callback->($status)
		531
		532	This is a composite request that tries to fully load the given file into
		533	memory. Status is the same as with aio_read.
		534
		535	=cut
		536
		537	sub aio_load($$;$) {
		538	aio_block {
		539	my ($path, undef, $cb) = @_;
		540	my $data = \$_[1];
		541
		542	my $pri = aioreq_pri;
		543	my $grp = aio_group $cb;
		544
		545	aioreq_pri $pri;
		546	add $grp aio_open $path, O_RDONLY, 0, sub {
		547	my $fh = shift
		548	or return $grp->result (-1);
		549
		550	aioreq_pri $pri;
		551	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		552	$grp->result ($_[0]);
		553	};
		554	};
		555
		556	$grp
		557	}
		558	}
		559
		560	=item aio_copy $srcpath, $dstpath, $callback->($status)
		561
		562	Try to copy the I<file> (directories not supported as either source or
		563	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		564	the C<0> (error) or C<-1> ok.
		565
		566	This is a composite request that it creates the destination file with
		567	mode 0200 and copies the contents of the source file into it using
		568	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		569	uid/gid, in that order.
		570
		571	If an error occurs, the partial destination file will be unlinked, if
		572	possible, except when setting atime, mtime, access mode and uid/gid, where
		573	errors are being ignored.
		574
		575	=cut
		576
		577	sub aio_copy($$;$) {
		578	aio_block {
		579	my ($src, $dst, $cb) = @_;
		580
		581	my $pri = aioreq_pri;
		582	my $grp = aio_group $cb;
		583
		584	aioreq_pri $pri;
		585	add $grp aio_open $src, O_RDONLY, 0, sub {
		586	if (my $src_fh = $_[0]) {
		587	my @stat = stat $src_fh;
		588
		589	aioreq_pri $pri;
		590	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		591	if (my $dst_fh = $_[0]) {
		592	aioreq_pri $pri;
		593	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		594	if ($_[0] == $stat[7]) {
		595	$grp->result (0);
		596	close $src_fh;
		597
		598	# those should not normally block. should. should.
		599	utime $stat[8], $stat[9], $dst;
		600	chmod $stat[2] & 07777, $dst_fh;
		601	chown $stat[4], $stat[5], $dst_fh;
		602	close $dst_fh;
		603	} else {
		604	$grp->result (-1);
		605	close $src_fh;
		606	close $dst_fh;
		607
		608	aioreq $pri;
		609	add $grp aio_unlink $dst;
		610	}
		611	};
		612	} else {
		613	$grp->result (-1);
		614	}
		615	},
		616
		617	} else {
		618	$grp->result (-1);
		619	}
		620	};
		621
		622	$grp
		623	}
		624	}
		625
		626	=item aio_move $srcpath, $dstpath, $callback->($status)
		627
		628	Try to move the I<file> (directories not supported as either source or
		629	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		630	the C<0> (error) or C<-1> ok.
		631
		632	This is a composite request that tries to rename(2) the file first. If
		633	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		634	that is successful, unlinking the C<$srcpath>.
		635
		636	=cut
		637
		638	sub aio_move($$;$) {
		639	aio_block {
		640	my ($src, $dst, $cb) = @_;
		641
		642	my $pri = aioreq_pri;
		643	my $grp = aio_group $cb;
		644
		645	aioreq_pri $pri;
		646	add $grp aio_rename $src, $dst, sub {
		647	if ($_[0] && $! == EXDEV) {
		648	aioreq_pri $pri;
		649	add $grp aio_copy $src, $dst, sub {
		650	$grp->result ($_[0]);
		651
		652	if (!$_[0]) {
		653	aioreq_pri $pri;
		654	add $grp aio_unlink $src;
		655	}
		656	};
		657	} else {
		658	$grp->result ($_[0]);
		659	}
		660	};
		661
		662	$grp
		663	}
		664	}
		665
329	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	666	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
330		667
331	Scans a directory (similar to C<aio_readdir>) and tries to separate the	668	Scans a directory (similar to C<aio_readdir>) but additionally tries to
332	entries of directory C<$path> into two sets of names, ones you can recurse	669	efficiently separate the entries of directory C<$path> into two sets of
333	into (directories), and ones you cannot recurse into (everything else).	670	names, directories you can recurse into (directories), and ones you cannot
		671	recurse into (everything else, including symlinks to directories).
334		672
335	C<aio_scandir> is a composite request that consists of many	673	C<aio_scandir> is a composite request that creates of many sub requests_
336	aio-primitives. C<$maxreq> specifies the maximum number of outstanding	674	C<$maxreq> specifies the maximum number of outstanding aio requests that
337	aio requests that this function generates. If it is C<< <= 0 >>, then a	675	this function generates. If it is C<< <= 0 >>, then a suitable default
338	suitable default will be chosen (currently 8).	676	will be chosen (currently 4).
339		677
340	On error, the callback is called without arguments, otherwise it receives	678	On error, the callback is called without arguments, otherwise it receives
341	two array-refs with path-relative entry names.	679	two array-refs with path-relative entry names.
342		680
343	Example:	681	Example:
…		…
351	Implementation notes.	689	Implementation notes.
352		690
353	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	691	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
354		692
355	After reading the directory, the modification time, size etc. of the	693	After reading the directory, the modification time, size etc. of the
356	directory before and after the readdir is checked, and if they match, the	694	directory before and after the readdir is checked, and if they match (and
357	link count will be used to decide how many entries are directories (if	695	isn't the current time), the link count will be used to decide how many
358	>= 2). Otherwise, no knowledge of the number of subdirectories will be	696	entries are directories (if >= 2). Otherwise, no knowledge of the number
359	assumed.	697	of subdirectories will be assumed.
360		698
361	Then entires will be sorted into likely directories (everything without a	699	Then entries will be sorted into likely directories (everything without
362	non-initial dot) and likely non-directories (everything else). Then every	700	a non-initial dot currently) and likely non-directories (everything
363	entry + C</.> will be C<stat>'ed, likely directories first. This is often	701	else). Then every entry plus an appended C</.> will be C<stat>'ed,
		702	likely directories first. If that succeeds, it assumes that the entry
		703	is a directory or a symlink to directory (which will be checked
		704	seperately). This is often faster than stat'ing the entry itself because
364	faster because filesystems might detect the type of the entry without	705	filesystems might detect the type of the entry without reading the inode
365	reading the inode data (e.g. ext2fs filetype feature). If that succeeds,	706	data (e.g. ext2fs filetype feature).
366	it assumes that the entry is a directory or a symlink to directory (which
367	will be checked seperately).
368		707
369	If the known number of directories has been reached, the rest of the	708	If the known number of directories (link count - 2) has been reached, the
370	entries is assumed to be non-directories.	709	rest of the entries is assumed to be non-directories.
		710
		711	This only works with certainty on POSIX (= UNIX) filesystems, which
		712	fortunately are the vast majority of filesystems around.
		713
		714	It will also likely work on non-POSIX filesystems with reduced efficiency
		715	as those tend to return 0 or 1 as link counts, which disables the
		716	directory counting heuristic.
371		717
372	=cut	718	=cut
373		719
374	sub aio_scandir($$$) {	720	sub aio_scandir($$;$) {
		721	aio_block {
375	my ($path, $maxreq, $cb) = @_;	722	my ($path, $maxreq, $cb) = @_;
376		723
		724	my $pri = aioreq_pri;
		725
		726	my $grp = aio_group $cb;
		727
377	$maxreq = 8 if $maxreq <= 0;	728	$maxreq = 4 if $maxreq <= 0;
378		729
379	# stat once	730	# stat once
		731	aioreq_pri $pri;
380	aio_stat $path, sub {	732	add $grp aio_stat $path, sub {
381	return $cb->() if $_[0];	733	return $grp->result () if $_[0];
		734	my $now = time;
382	my $hash1 = join ":", (stat _)[0,1,3,7,9];	735	my $hash1 = join ":", (stat _)[0,1,3,7,9];
383		736
384	# read the directory entries	737	# read the directory entries
		738	aioreq_pri $pri;
385	aio_readdir $path, sub {	739	add $grp aio_readdir $path, sub {
386	my $entries = shift	740	my $entries = shift
387	or return $cb->();	741	or return $grp->result ();
388		742
389	# stat the dir another time	743	# stat the dir another time
		744	aioreq_pri $pri;
390	aio_stat $path, sub {	745	add $grp aio_stat $path, sub {
391	my $hash2 = join ":", (stat _)[0,1,3,7,9];	746	my $hash2 = join ":", (stat _)[0,1,3,7,9];
392		747
393	my $ndirs;	748	my $ndirs;
394		749
395	# take the slow route if anything looks fishy	750	# take the slow route if anything looks fishy
396	if ($hash1 ne $hash2) {	751	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
397	$ndirs = -1;	752	$ndirs = -1;
398	} else {	753	} else {
399	# if nlink == 2, we are finished	754	# if nlink == 2, we are finished
400	# on non-posix-fs's, we rely on nlink < 2	755	# on non-posix-fs's, we rely on nlink < 2
401	$ndirs = (stat _)[3] - 2	756	$ndirs = (stat _)[3] - 2
402	or return $cb->([], $entries);	757	or return $grp->result ([], $entries);
403	}
404
405	# sort into likely dirs and likely nondirs
406	# dirs == files without ".", short entries first
407	$entries = [map $_->[0],
408	sort { $b->[1] cmp $a->[1] }
409	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
410	@$entries];
411
412	my (@dirs, @nondirs);
413
414	my ($statcb, $schedcb);
415	my $nreq = 0;
416
417	$schedcb = sub {
418	if (@$entries) {
419	if ($nreq < $maxreq) {
420	my $ent = pop @$entries;
421	$nreq++;
422	aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
423	}
424	} elsif (!$nreq) {
425	# finished
426	undef $statcb;
427	undef $schedcb;
428	$cb->(\@dirs, \@nondirs) if $cb;
429	undef $cb;
430	}	758	}
		759
		760	# sort into likely dirs and likely nondirs
		761	# dirs == files without ".", short entries first
		762	$entries = [map $_->[0],
		763	sort { $b->[1] cmp $a->[1] }
		764	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
		765	@$entries];
		766
		767	my (@dirs, @nondirs);
		768
		769	my $statgrp = add $grp aio_group sub {
		770	$grp->result (\@dirs, \@nondirs);
		771	};
		772
		773	limit $statgrp $maxreq;
		774	feed $statgrp sub {
		775	return unless @$entries;
		776	my $entry = pop @$entries;
		777
		778	aioreq_pri $pri;
		779	add $statgrp aio_stat "$path/$entry/.", sub {
		780	if ($_[0] < 0) {
		781	push @nondirs, $entry;
		782	} else {
		783	# need to check for real directory
		784	aioreq_pri $pri;
		785	add $statgrp aio_lstat "$path/$entry", sub {
		786	if (-d _) {
		787	push @dirs, $entry;
		788
		789	unless (--$ndirs) {
		790	push @nondirs, @$entries;
		791	feed $statgrp;
		792	}
		793	} else {
		794	push @nondirs, $entry;
		795	}
		796	}
		797	}
		798	};
		799	};
431	};	800	};
432	$statcb = sub {
433	my ($status, $entry) = @_;
434
435	if ($status < 0) {
436	$nreq--;
437	push @nondirs, $entry;
438	&$schedcb;
439	} else {
440	# need to check for real directory
441	aio_lstat "$path/$entry", sub {
442	$nreq--;
443
444	if (-d _) {
445	push @dirs, $entry;
446
447	if (!--$ndirs) {
448	push @nondirs, @$entries;
449	$entries = [];
450	}
451	} else {
452	push @nondirs, $entry;
453	}
454
455	&$schedcb;
456	}
457	}
458	};
459
460	&$schedcb while @$entries && $nreq < $maxreq;
461	};	801	};
462	};	802	};
		803
		804	$grp
463	};	805	}
		806	}
		807
		808	=item aio_rmtree $path, $callback->($status)
		809
		810	Delete a directory tree starting (and including) C<$path>, return the
		811	status of the final C<rmdir> only. This is a composite request that
		812	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		813	everything else.
		814
		815	=cut
		816
		817	sub aio_rmtree;
		818	sub aio_rmtree($;$) {
		819	aio_block {
		820	my ($path, $cb) = @_;
		821
		822	my $pri = aioreq_pri;
		823	my $grp = aio_group $cb;
		824
		825	aioreq_pri $pri;
		826	add $grp aio_scandir $path, 0, sub {
		827	my ($dirs, $nondirs) = @_;
		828
		829	my $dirgrp = aio_group sub {
		830	add $grp aio_rmdir $path, sub {
		831	$grp->result ($_[0]);
		832	};
		833	};
		834
		835	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		836	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		837
		838	add $grp $dirgrp;
		839	};
		840
		841	$grp
		842	}
464	}	843	}
465		844
466	=item aio_fsync $fh, $callback->($status)	845	=item aio_fsync $fh, $callback->($status)
467		846
468	Asynchronously call fsync on the given filehandle and call the callback	847	Asynchronously call fsync on the given filehandle and call the callback
…		…
474	callback with the fdatasync result code.	853	callback with the fdatasync result code.
475		854
476	If this call isn't available because your OS lacks it or it couldn't be	855	If this call isn't available because your OS lacks it or it couldn't be
477	detected, it will be emulated by calling C<fsync> instead.	856	detected, it will be emulated by calling C<fsync> instead.
478		857
		858	=item aio_group $callback->(...)
		859
		860	This is a very special aio request: Instead of doing something, it is a
		861	container for other aio requests, which is useful if you want to bundle
		862	many requests into a single, composite, request with a definite callback
		863	and the ability to cancel the whole request with its subrequests.
		864
		865	Returns an object of class L<IO::AIO::GRP>. See its documentation below
		866	for more info.
		867
		868	Example:
		869
		870	my $grp = aio_group sub {
		871	print "all stats done\n";
		872	};
		873
		874	add $grp
		875	(aio_stat ...),
		876	(aio_stat ...),
		877	...;
		878
		879	=item aio_nop $callback->()
		880
		881	This is a special request - it does nothing in itself and is only used for
		882	side effects, such as when you want to add a dummy request to a group so
		883	that finishing the requests in the group depends on executing the given
		884	code.
		885
		886	While this request does nothing, it still goes through the execution
		887	phase and still requires a worker thread. Thus, the callback will not
		888	be executed immediately but only after other requests in the queue have
		889	entered their execution phase. This can be used to measure request
		890	latency.
		891
		892	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
		893
		894	Mainly used for debugging and benchmarking, this aio request puts one of
		895	the request workers to sleep for the given time.
		896
		897	While it is theoretically handy to have simple I/O scheduling requests
		898	like sleep and file handle readable/writable, the overhead this creates is
		899	immense (it blocks a thread for a long time) so do not use this function
		900	except to put your application under artificial I/O pressure.
		901
479	=back	902	=back
480		903
		904	=head2 IO::AIO::REQ CLASS
		905
		906	All non-aggregate C<aio_*> functions return an object of this class when
		907	called in non-void context.
		908
		909	=over 4
		910
		911	=item cancel $req
		912
		913	Cancels the request, if possible. Has the effect of skipping execution
		914	when entering the B<execute> state and skipping calling the callback when
		915	entering the the B<result> state, but will leave the request otherwise
		916	untouched. That means that requests that currently execute will not be
		917	stopped and resources held by the request will not be freed prematurely.
		918
		919	=item cb $req $callback->(...)
		920
		921	Replace (or simply set) the callback registered to the request.
		922
		923	=back
		924
		925	=head2 IO::AIO::GRP CLASS
		926
		927	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
		928	objects of this class, too.
		929
		930	A IO::AIO::GRP object is a special request that can contain multiple other
		931	aio requests.
		932
		933	You create one by calling the C<aio_group> constructing function with a
		934	callback that will be called when all contained requests have entered the
		935	C<done> state:
		936
		937	my $grp = aio_group sub {
		938	print "all requests are done\n";
		939	};
		940
		941	You add requests by calling the C<add> method with one or more
		942	C<IO::AIO::REQ> objects:
		943
		944	$grp->add (aio_unlink "...");
		945
		946	add $grp aio_stat "...", sub {
		947	$_[0] or return $grp->result ("error");
		948
		949	# add another request dynamically, if first succeeded
		950	add $grp aio_open "...", sub {
		951	$grp->result ("ok");
		952	};
		953	};
		954
		955	This makes it very easy to create composite requests (see the source of
		956	C<aio_move> for an application) that work and feel like simple requests.
		957
		958	=over 4
		959
		960	=item * The IO::AIO::GRP objects will be cleaned up during calls to
		961	C<IO::AIO::poll_cb>, just like any other request.
		962
		963	=item * They can be canceled like any other request. Canceling will cancel not
		964	only the request itself, but also all requests it contains.
		965
		966	=item * They can also can also be added to other IO::AIO::GRP objects.
		967
		968	=item * You must not add requests to a group from within the group callback (or
		969	any later time).
		970
		971	=back
		972
		973	Their lifetime, simplified, looks like this: when they are empty, they
		974	will finish very quickly. If they contain only requests that are in the
		975	C<done> state, they will also finish. Otherwise they will continue to
		976	exist.
		977
		978	That means after creating a group you have some time to add requests. And
		979	in the callbacks of those requests, you can add further requests to the
		980	group. And only when all those requests have finished will the the group
		981	itself finish.
		982
		983	=over 4
		984
		985	=item add $grp ...
		986
		987	=item $grp->add (...)
		988
		989	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		990	be added, including other groups, as long as you do not create circular
		991	dependencies.
		992
		993	Returns all its arguments.
		994
		995	=item $grp->cancel_subs
		996
		997	Cancel all subrequests and clears any feeder, but not the group request
		998	itself. Useful when you queued a lot of events but got a result early.
		999
		1000	=item $grp->result (...)
		1001
		1002	Set the result value(s) that will be passed to the group callback when all
		1003	subrequests have finished and set thre groups errno to the current value
		1004	of errno (just like calling C<errno> without an error number). By default,
		1005	no argument will be passed and errno is zero.
		1006
		1007	=item $grp->errno ([$errno])
		1008
		1009	Sets the group errno value to C<$errno>, or the current value of errno
		1010	when the argument is missing.
		1011
		1012	Every aio request has an associated errno value that is restored when
		1013	the callback is invoked. This method lets you change this value from its
		1014	default (0).
		1015
		1016	Calling C<result> will also set errno, so make sure you either set C<$!>
		1017	before the call to C<result>, or call c<errno> after it.
		1018
		1019	=item feed $grp $callback->($grp)
		1020
		1021	Sets a feeder/generator on this group: every group can have an attached
		1022	generator that generates requests if idle. The idea behind this is that,
		1023	although you could just queue as many requests as you want in a group,
		1024	this might starve other requests for a potentially long time. For
		1025	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		1026	requests, delaying any later requests for a long time.
		1027
		1028	To avoid this, and allow incremental generation of requests, you can
		1029	instead a group and set a feeder on it that generates those requests. The
		1030	feed callback will be called whenever there are few enough (see C<limit>,
		1031	below) requests active in the group itself and is expected to queue more
		1032	requests.
		1033
		1034	The feed callback can queue as many requests as it likes (i.e. C<add> does
		1035	not impose any limits).
		1036
		1037	If the feed does not queue more requests when called, it will be
		1038	automatically removed from the group.
		1039
		1040	If the feed limit is C<0>, it will be set to C<2> automatically.
		1041
		1042	Example:
		1043
		1044	# stat all files in @files, but only ever use four aio requests concurrently:
		1045
		1046	my $grp = aio_group sub { print "finished\n" };
		1047	limit $grp 4;
		1048	feed $grp sub {
		1049	my $file = pop @files
		1050	or return;
		1051
		1052	add $grp aio_stat $file, sub { ... };
		1053	};
		1054
		1055	=item limit $grp $num
		1056
		1057	Sets the feeder limit for the group: The feeder will be called whenever
		1058	the group contains less than this many requests.
		1059
		1060	Setting the limit to C<0> will pause the feeding process.
		1061
		1062	=back
		1063
481	=head2 SUPPORT FUNCTIONS	1064	=head2 SUPPORT FUNCTIONS
		1065
		1066	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
482		1067
483	=over 4	1068	=over 4
484		1069
485	=item $fileno = IO::AIO::poll_fileno	1070	=item $fileno = IO::AIO::poll_fileno
486		1071
…		…
491		1076
492	See C<poll_cb> for an example.	1077	See C<poll_cb> for an example.
493		1078
494	=item IO::AIO::poll_cb	1079	=item IO::AIO::poll_cb
495		1080
496	Process all outstanding events on the result pipe. You have to call this	1081	Process some outstanding events on the result pipe. You have to call this
497	regularly. Returns the number of events processed. Returns immediately	1082	regularly. Returns the number of events processed. Returns immediately
498	when no events are outstanding.	1083	when no events are outstanding. The amount of events processed depends on
		1084	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1085
		1086	If not all requests were processed for whatever reason, the filehandle
		1087	will still be ready when C<poll_cb> returns.
499		1088
500	Example: Install an Event watcher that automatically calls	1089	Example: Install an Event watcher that automatically calls
501	IO::AIO::poll_cb with high priority:	1090	IO::AIO::poll_cb with high priority:
502		1091
503	Event->io (fd => IO::AIO::poll_fileno,	1092	Event->io (fd => IO::AIO::poll_fileno,
504	poll => 'r', async => 1,	1093	poll => 'r', async => 1,
505	cb => \&IO::AIO::poll_cb);	1094	cb => \&IO::AIO::poll_cb);
506		1095
		1096	=item IO::AIO::max_poll_reqs $nreqs
		1097
		1098	=item IO::AIO::max_poll_time $seconds
		1099
		1100	These set the maximum number of requests (default C<0>, meaning infinity)
		1101	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1102	the maximum amount of time (default C<0>, meaning infinity) spent in
		1103	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1104	of time C<poll_cb> is allowed to use).
		1105
		1106	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1107	syscall per request processed, which is not normally a problem unless your
		1108	callbacks are really really fast or your OS is really really slow (I am
		1109	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1110
		1111	Setting these is useful if you want to ensure some level of
		1112	interactiveness when perl is not fast enough to process all requests in
		1113	time.
		1114
		1115	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1116
		1117	Example: Install an Event watcher that automatically calls
		1118	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1119	program get the CPU sometimes even under high AIO load.
		1120
		1121	# try not to spend much more than 0.1s in poll_cb
		1122	IO::AIO::max_poll_time 0.1;
		1123
		1124	# use a low priority so other tasks have priority
		1125	Event->io (fd => IO::AIO::poll_fileno,
		1126	poll => 'r', nice => 1,
		1127	cb => &IO::AIO::poll_cb);
		1128
507	=item IO::AIO::poll_wait	1129	=item IO::AIO::poll_wait
508		1130
		1131	If there are any outstanding requests and none of them in the result
509	Wait till the result filehandle becomes ready for reading (simply does a	1132	phase, wait till the result filehandle becomes ready for reading (simply
510	C<select> on the filehandle. This is useful if you want to synchronously wait	1133	does a C<select> on the filehandle. This is useful if you want to
511	for some requests to finish).	1134	synchronously wait for some requests to finish).
512		1135
513	See C<nreqs> for an example.	1136	See C<nreqs> for an example.
514		1137
		1138	=item IO::AIO::poll
		1139
		1140	Waits until some requests have been handled.
		1141
		1142	Returns the number of requests processed, but is otherwise strictly
		1143	equivalent to:
		1144
		1145	IO::AIO::poll_wait, IO::AIO::poll_cb
		1146
515	=item IO::AIO::nreqs	1147	=item IO::AIO::flush
516		1148
517	Returns the number of requests currently outstanding (i.e. for which their	1149	Wait till all outstanding AIO requests have been handled.
518	callback has not been invoked yet).
519		1150
520	Example: wait till there are no outstanding requests anymore:	1151	Strictly equivalent to:
521		1152
522	IO::AIO::poll_wait, IO::AIO::poll_cb	1153	IO::AIO::poll_wait, IO::AIO::poll_cb
523	while IO::AIO::nreqs;	1154	while IO::AIO::nreqs;
524		1155
525	=item IO::AIO::flush	1156	=back
526		1157
527	Wait till all outstanding AIO requests have been handled.	1158	=head3 CONTROLLING THE NUMBER OF THREADS
528		1159
529	Strictly equivalent to:	1160	=over
530
531	IO::AIO::poll_wait, IO::AIO::poll_cb
532	while IO::AIO::nreqs;
533
534	=item IO::AIO::poll
535
536	Waits until some requests have been handled.
537
538	Strictly equivalent to:
539
540	IO::AIO::poll_wait, IO::AIO::poll_cb
541	if IO::AIO::nreqs;
542		1161
543	=item IO::AIO::min_parallel $nthreads	1162	=item IO::AIO::min_parallel $nthreads
544		1163
545	Set the minimum number of AIO threads to C<$nthreads>. The current default	1164	Set the minimum number of AIO threads to C<$nthreads>. The current
546	is C<4>, which means four asynchronous operations can be done at one time	1165	default is C<8>, which means eight asynchronous operations can execute
547	(the number of outstanding operations, however, is unlimited).	1166	concurrently at any one time (the number of outstanding requests,
		1167	however, is unlimited).
548		1168
549	IO::AIO starts threads only on demand, when an AIO request is queued and	1169	IO::AIO starts threads only on demand, when an AIO request is queued and
550	no free thread exists.	1170	no free thread exists. Please note that queueing up a hundred requests can
		1171	create demand for a hundred threads, even if it turns out that everything
		1172	is in the cache and could have been processed faster by a single thread.
551		1173
552	It is recommended to keep the number of threads low, as some Linux	1174	It is recommended to keep the number of threads relatively low, as some
553	kernel versions will scale negatively with the number of threads (higher	1175	Linux kernel versions will scale negatively with the number of threads
554	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1176	(higher parallelity => MUCH higher latency). With current Linux 2.6
555	threads should be fine.	1177	versions, 4-32 threads should be fine.
556		1178
557	Under most circumstances you don't need to call this function, as the	1179	Under most circumstances you don't need to call this function, as the
558	module selects a default that is suitable for low to moderate load.	1180	module selects a default that is suitable for low to moderate load.
559		1181
560	=item IO::AIO::max_parallel $nthreads	1182	=item IO::AIO::max_parallel $nthreads
…		…
569	This module automatically runs C<max_parallel 0> at program end, to ensure	1191	This module automatically runs C<max_parallel 0> at program end, to ensure
570	that all threads are killed and that there are no outstanding requests.	1192	that all threads are killed and that there are no outstanding requests.
571		1193
572	Under normal circumstances you don't need to call this function.	1194	Under normal circumstances you don't need to call this function.
573		1195
		1196	=item IO::AIO::max_idle $nthreads
		1197
		1198	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1199	threads that did not get a request to process within 10 seconds). That
		1200	means if a thread becomes idle while C<$nthreads> other threads are also
		1201	idle, it will free its resources and exit.
		1202
		1203	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1204	to allow for extremely high load situations, but want to free resources
		1205	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1206
		1207	The default is probably ok in most situations, especially if thread
		1208	creation is fast. If thread creation is very slow on your system you might
		1209	want to use larger values.
		1210
574	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1211	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		1212
		1213	This is a very bad function to use in interactive programs because it
		1214	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1215	use an C<aio_group> together with a feed callback.
575		1216
576	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1217	Sets the maximum number of outstanding requests to C<$nreqs>. If you
577	try to queue up more than this number of requests, the caller will block until	1218	do queue up more than this number of requests, the next call to the
578	some requests have been handled.	1219	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1220	function will block until the limit is no longer exceeded.
579		1221
580	The default is very large, so normally there is no practical limit. If you	1222	The default value is very large, so there is no practical limit on the
581	queue up many requests in a loop it often improves speed if you set	1223	number of outstanding requests.
582	this to a relatively low number, such as C<100>.
583		1224
584	Under normal circumstances you don't need to call this function.	1225	You can still queue as many requests as you want. Therefore,
		1226	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		1227	as a stop gap to shield against fatal memory overflow (with large values).
585		1228
586	=back	1229	=back
587		1230
		1231	=head3 STATISTICAL INFORMATION
		1232
		1233	=over
		1234
		1235	=item IO::AIO::nreqs
		1236
		1237	Returns the number of requests currently in the ready, execute or pending
		1238	states (i.e. for which their callback has not been invoked yet).
		1239
		1240	Example: wait till there are no outstanding requests anymore:
		1241
		1242	IO::AIO::poll_wait, IO::AIO::poll_cb
		1243	while IO::AIO::nreqs;
		1244
		1245	=item IO::AIO::nready
		1246
		1247	Returns the number of requests currently in the ready state (not yet
		1248	executed).
		1249
		1250	=item IO::AIO::npending
		1251
		1252	Returns the number of requests currently in the pending state (executed,
		1253	but not yet processed by poll_cb).
		1254
		1255	=back
		1256
588	=cut	1257	=cut
589		1258
590	# support function to convert a fd into a perl filehandle
591	sub _fd2fh {
592	return undef if $_[0] < 0;
593
594	# try to generate nice filehandles
595	my $sym = "IO::AIO::fd#$_[0]";
596	local *$sym;
597
598	open *$sym, "+<&=$_[0]" # usually works under any unix
599	or open *$sym, "<&=$_[0]" # cygwin needs this
600	or open *$sym, ">&=$_[0]" # or this
601	or return undef;
602
603	*$sym
604	}
605
606	min_parallel 4;	1259	min_parallel 8;
607		1260
608	END {	1261	END { flush }
609	max_parallel 0;
610	}
611		1262
612	1;	1263	1;
613		1264
614	=head2 FORK BEHAVIOUR	1265	=head2 FORK BEHAVIOUR
		1266
		1267	This module should do "the right thing" when the process using it forks:
615		1268
616	Before the fork, IO::AIO enters a quiescent state where no requests	1269	Before the fork, IO::AIO enters a quiescent state where no requests
617	can be added in other threads and no results will be processed. After	1270	can be added in other threads and no results will be processed. After
618	the fork the parent simply leaves the quiescent state and continues	1271	the fork the parent simply leaves the quiescent state and continues
619	request/result processing, while the child clears the request/result	1272	request/result processing, while the child frees the request/result queue
620	queue (so the requests started before the fork will only be handled in	1273	(so that the requests started before the fork will only be handled in the
621	the parent). Threats will be started on demand until the limit ste in the	1274	parent). Threads will be started on demand until the limit set in the
622	parent process has been reached again.	1275	parent process has been reached again.
623		1276
		1277	In short: the parent will, after a short pause, continue as if fork had
		1278	not been called, while the child will act as if IO::AIO has not been used
		1279	yet.
		1280
		1281	=head2 MEMORY USAGE
		1282
		1283	Per-request usage:
		1284
		1285	Each aio request uses - depending on your architecture - around 100-200
		1286	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1287	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1288	scalars and other data passed into aio requests will also be locked and
		1289	will consume memory till the request has entered the done state.
		1290
		1291	This is not awfully much, so queuing lots of requests is not usually a
		1292	problem.
		1293
		1294	Per-thread usage:
		1295
		1296	In the execution phase, some aio requests require more memory for
		1297	temporary buffers, and each thread requires a stack and other data
		1298	structures (usually around 16k-128k, depending on the OS).
		1299
		1300	=head1 KNOWN BUGS
		1301
		1302	Known bugs will be fixed in the next release.
		1303
624	=head1 SEE ALSO	1304	=head1 SEE ALSO
625		1305
626	L<Coro>, L<Linux::AIO>.	1306	L<Coro::AIO>.
627		1307
628	=head1 AUTHOR	1308	=head1 AUTHOR
629		1309
630	Marc Lehmann <schmorp@schmorp.de>	1310	Marc Lehmann <schmorp@schmorp.de>
631	http://home.schmorp.de/	1311	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.51 by root, Sat Jun 24 19:14:04 2006 UTC vs. Revision 1.116 by root, Wed Oct 3 21:27:51 2007 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.51 by root, Sat Jun 24 19:14:04 2006 UTC vs.
Revision 1.116 by root, Wed Oct 3 21:27:51 2007 UTC