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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.1 by root, Sun Jul 10 17:07:44 2005 UTC vs.
Revision 1.27 by root, Tue Aug 16 22:22:18 2005 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
		9	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		10	my ($fh) = @_;
		11	...
		12	};
		13
		14	aio_unlink "/tmp/file", sub { };
		15
		16	aio_read $fh, 30000, 1024, $buffer, 0, sub {
		17	$_[0] > 0 or die "read error: $!";
		18	};
		19
		20	# Event
		21	Event->io (fd => IO::AIO::poll_fileno,
		22	poll => 'r',
		23	cb => \&IO::AIO::poll_cb);
		24
		25	# Glib/Gtk2
		26	add_watch Glib::IO IO::AIO::poll_fileno,
		27	in => sub { IO::AIO::poll_cb; 1 };
		28
		29	# Tk
		30	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		31	readable => \&IO::AIO::poll_cb);
		32
		33	# Danga::Socket
		34	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		35	\&IO::AIO::poll_cb);
		36
		37
9	=head1 DESCRIPTION	38	=head1 DESCRIPTION
10		39
11	This module implements asynchronous I/O using whatever means your	40	This module implements asynchronous I/O using whatever means your
12	operating system supports. Currently, it falls back to Linux::AIO if that	41	operating system supports.
13	module is available, or uses pthreads to emulato aio functionality.
14		42
15	Currently, in this module a number of threads are started that execute	43	Currently, a number of threads are started that execute your read/writes
16	your read/writes and signal their completion. You don't need thread	44	and signal their completion. You don't need thread support in your libc or
17	support in your libc or perl, and the threads created by this module will	45	perl, and the threads created by this module will not be visible to the
18	not be visible to the pthreads library.	46	pthreads library. In the future, this module might make use of the native
		47	aio functions available on many operating systems. However, they are often
		48	not well-supported (Linux doesn't allow them on normal files currently,
		49	for example), and they would only support aio_read and aio_write, so the
		50	remaining functionality would have to be implemented using threads anyway.
19		51
20	Although the module will work with in the presence of other threads, it is	52	Although the module will work with in the presence of other threads, it is
21	not reentrant, so use appropriate locking yourself.	53	currently not reentrant, so use appropriate locking yourself, always call
22		54	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other
23	=head2 API NOTES	55	C<aio_> functions) recursively.
24
25	All the C<aio_*> calls are more or less thin wrappers around the syscall
26	with the same name (sans C<aio_>). The arguments are similar or identical,
27	and they all accept an additional C<$callback> argument which must be
28	a code reference. This code reference will get called with the syscall
29	return code (e.g. most syscalls return C<-1> on error, unlike perl, which
30	usually delivers "false") as it's sole argument when the given syscall has
31	been executed asynchronously.
32
33	All functions that expect a filehandle will also accept a file descriptor.
34
35	The filenames you pass to these routines I<must> be absolute. The reason
36	is that at the time the request is being executed, the current working
37	directory could have changed. Alternatively, you can make sure that you
38	never change the current working directory.
39
40	=over 4
41		56
42	=cut	57	=cut
43		58
44	package IO::AIO;	59	package IO::AIO;
45		60
		61	no warnings;
		62
46	use base 'Exporter';	63	use base 'Exporter';
47		64
		65	use Fcntl ();
		66
48	BEGIN {	67	BEGIN {
49	$VERSION = 0.1;	68	$VERSION = 1.1;
50		69
51	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink	70	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink
52	aio_fsync aio_fdatasync aio_readahead);	71	aio_rmdir aio_symlink aio_fsync aio_fdatasync aio_readahead);
53	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs);	72	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);
54		73
55	require XSLoader;	74	require XSLoader;
56	XSLoader::load IO::AIO, $VERSION;	75	XSLoader::load IO::AIO, $VERSION;
57	}	76	}
58		77
59	=item IO::AIO::min_parallel $nthreads	78	=head1 FUNCTIONS
60		79
61	Set the minimum number of AIO threads to C<$nthreads>. The default is	80	=head2 AIO FUNCTIONS
62	C<1>, which means a single asynchronous operation can be done at one time
63	(the number of outstanding operations, however, is unlimited).
64		81
65	It is recommended to keep the number of threads low, as some linux	82	All the C<aio_*> calls are more or less thin wrappers around the syscall
66	kernel versions will scale negatively with the number of threads (higher	83	with the same name (sans C<aio_>). The arguments are similar or identical,
67	parallelity => MUCH higher latency).	84	and they all accept an additional (and optional) C<$callback> argument
		85	which must be a code reference. This code reference will get called with
		86	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
		87	perl, which usually delivers "false") as it's sole argument when the given
		88	syscall has been executed asynchronously.
68		89
69	Under normal circumstances you don't need to call this function, as this	90	All functions expecting a filehandle keep a copy of the filehandle
70	module automatically starts a single async thread.	91	internally until the request has finished.
71		92
72	=item IO::AIO::max_parallel $nthreads	93	The filenames you pass to these routines I<must> be absolute. The reason
		94	for this is that at the time the request is being executed, the current
		95	working directory could have changed. Alternatively, you can make sure
		96	that you never change the current working directory.
73		97
74	Sets the maximum number of AIO threads to C<$nthreads>. If more than	98	=over 4
75	the specified number of threads are currently running, kill them. This
76	function blocks until the limit is reached.
77
78	This module automatically runs C<max_parallel 0> at program end, to ensure
79	that all threads are killed and that there are no outstanding requests.
80
81	Under normal circumstances you don't need to call this function.
82
83	=item $fileno = IO::AIO::poll_fileno
84
85	Return the I<request result pipe filehandle>. This filehandle must be
86	polled for reading by some mechanism outside this module (e.g. Event
87	or select, see below). If the pipe becomes readable you have to call
88	C<poll_cb> to check the results.
89
90	See C<poll_cb> for an example.
91
92	=item IO::AIO::poll_cb
93
94	Process all outstanding events on the result pipe. You have to call this
95	regularly. Returns the number of events processed. Returns immediately
96	when no events are outstanding.
97
98	You can use Event to multiplex, e.g.:
99
100	Event->io (fd => IO::AIO::poll_fileno,
101	poll => 'r', async => 1,
102	cb => \&IO::AIO::poll_cb);
103
104	=item IO::AIO::poll_wait
105
106	Wait till the result filehandle becomes ready for reading (simply does a
107	select on the filehandle. This is useful if you want to synchronously wait
108	for some requests to finish).
109
110	See C<nreqs> for an example.
111
112	=item IO::AIO::nreqs
113
114	Returns the number of requests currently outstanding.
115
116	Example: wait till there are no outstanding requests anymore:
117
118	IO::AIO::poll_wait, IO::AIO::poll_cb
119	while IO::AIO::nreqs;
120		99
121	=item aio_open $pathname, $flags, $mode, $callback	100	=item aio_open $pathname, $flags, $mode, $callback
122		101
123	Asynchronously open or create a file and call the callback with the	102	Asynchronously open or create a file and call the callback with a newly
124	filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this	103	created filehandle for the file.
125	might change in the future).
126		104
127	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	105	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
128	for an explanation.	106	for an explanation.
129		107
130	The C<$mode> argument is a bitmask. See the C<Fcntl> module for a	108	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
131	list. They are the same as used in C<sysopen>.	109	list. They are the same as used by C<sysopen>.
		110
		111	Likewise, C<$mode> specifies the mode of the newly created file, if it
		112	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
		113	except that it is mandatory (i.e. use C<0> if you don't create new files,
		114	and C<0666> or C<0777> if you do).
132		115
133	Example:	116	Example:
134		117
135	aio_open "/etc/passwd", O_RDONLY, 0, sub {	118	aio_open "/etc/passwd", O_RDONLY, 0, sub {
136	if ($_[0] >= 0) {	119	if ($_[0]) {
137	open my $fh, "<&$_[0]"; # create a copy for perl
138	aio_close $_[0], sub { }; # close the aio handle
139	print "open successful, fh is $fh\n";	120	print "open successful, fh is $_[0]\n";
140	...	121	...
141	} else {	122	} else {
142	die "open failed: $!\n";	123	die "open failed: $!\n";
143	}	124	}
144	};	125	};
145		126
146	=item aio_close $fh, $callback	127	=item aio_close $fh, $callback
147		128
148	Asynchronously close a file and call the callback with the result code.	129	Asynchronously close a file and call the callback with the result
		130	code. I<WARNING:> although accepted, you should not pass in a perl
		131	filehandle here, as perl will likely close the file descriptor another
		132	time when the filehandle is destroyed. Normally, you can safely call perls
		133	C<close> or just let filehandles go out of scope.
		134
		135	This is supposed to be a bug in the API, so that might change. It's
		136	therefore best to avoid this function.
149		137
150	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback	138	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
151		139
152	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback	140	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
153		141
154	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	142	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
155	into the scalar given by C<data> and offset C<dataoffset> and calls the	143	into the scalar given by C<data> and offset C<dataoffset> and calls the
156	callback without the actual number of bytes read (or -1 on error, just	144	callback without the actual number of bytes read (or -1 on error, just
157	like the syscall).	145	like the syscall).
158		146
159	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at	147	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
160	offset C<0> within the scalar:	148	offset C<0> within the scalar:
161		149
162	aio_read $fh, 7, 15, $buffer, 0, sub {	150	aio_read $fh, 7, 15, $buffer, 0, sub {
163	$_[0] >= 0 or die "read error: $!";	151	$_[0] > 0 or die "read error: $!";
164	print "read <$buffer>\n";	152	print "read $_[0] bytes: <$buffer>\n";
165	};	153	};
166		154
167	=item aio_readahead $fh,$offset,$length, $callback	155	=item aio_readahead $fh,$offset,$length, $callback
168		156
169	Asynchronously reads the specified byte range into the page cache, using
170	the C<readahead> syscall. If that syscall doesn't exist the status will be
171	C<-1> and C<$!> is set to ENOSYS.
172
173	readahead() populates the page cache with data from a file so that	157	C<aio_readahead> populates the page cache with data from a file so that
174	subsequent reads from that file will not block on disk I/O. The C<$offset>	158	subsequent reads from that file will not block on disk I/O. The C<$offset>
175	argument specifies the starting point from which data is to be read and	159	argument specifies the starting point from which data is to be read and
176	C<$length> specifies the number of bytes to be read. I/O is performed in	160	C<$length> specifies the number of bytes to be read. I/O is performed in
177	whole pages, so that offset is effectively rounded down to a page boundary	161	whole pages, so that offset is effectively rounded down to a page boundary
178	and bytes are read up to the next page boundary greater than or equal to	162	and bytes are read up to the next page boundary greater than or equal to
179	(off-set+length). aio_readahead() does not read beyond the end of the	163	(off-set+length). C<aio_readahead> does not read beyond the end of the
180	file. The current file offset of the file is left unchanged.	164	file. The current file offset of the file is left unchanged.
		165
		166	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
		167	emulated by simply reading the data, which would have a similar effect.
181		168
182	=item aio_stat $fh_or_path, $callback	169	=item aio_stat $fh_or_path, $callback
183		170
184	=item aio_lstat $fh, $callback	171	=item aio_lstat $fh, $callback
185		172
…		…
204	=item aio_unlink $pathname, $callback	191	=item aio_unlink $pathname, $callback
205		192
206	Asynchronously unlink (delete) a file and call the callback with the	193	Asynchronously unlink (delete) a file and call the callback with the
207	result code.	194	result code.
208		195
		196	=item aio_rmdir $pathname, $callback
		197
		198	Asynchronously rmdir (delete) a directory and call the callback with the
		199	result code.
		200
209	=item aio_fsync $fh, $callback	201	=item aio_fsync $fh, $callback
210		202
211	Asynchronously call fsync on the given filehandle and call the callback	203	Asynchronously call fsync on the given filehandle and call the callback
212	with the fsync result code.	204	with the fsync result code.
213		205
214	=item aio_fdatasync $fh, $callback	206	=item aio_fdatasync $fh, $callback
215		207
216	Asynchronously call fdatasync on the given filehandle and call the	208	Asynchronously call fdatasync on the given filehandle and call the
217	callback with the fdatasync result code.	209	callback with the fdatasync result code.
218		210
		211	If this call isn't available because your OS lacks it or it couldn't be
		212	detected, it will be emulated by calling C<fsync> instead.
		213
		214	=back
		215
		216	=head2 SUPPORT FUNCTIONS
		217
		218	=over 4
		219
		220	=item $fileno = IO::AIO::poll_fileno
		221
		222	Return the I<request result pipe file descriptor>. This filehandle must be
		223	polled for reading by some mechanism outside this module (e.g. Event or
		224	select, see below or the SYNOPSIS). If the pipe becomes readable you have
		225	to call C<poll_cb> to check the results.
		226
		227	See C<poll_cb> for an example.
		228
		229	=item IO::AIO::poll_cb
		230
		231	Process all outstanding events on the result pipe. You have to call this
		232	regularly. Returns the number of events processed. Returns immediately
		233	when no events are outstanding.
		234
		235	Example: Install an Event watcher that automatically calls
		236	IO::AIO::poll_cb with high priority:
		237
		238	Event->io (fd => IO::AIO::poll_fileno,
		239	poll => 'r', async => 1,
		240	cb => \&IO::AIO::poll_cb);
		241
		242	=item IO::AIO::poll_wait
		243
		244	Wait till the result filehandle becomes ready for reading (simply does a
		245	C<select> on the filehandle. This is useful if you want to synchronously wait
		246	for some requests to finish).
		247
		248	See C<nreqs> for an example.
		249
		250	=item IO::AIO::nreqs
		251
		252	Returns the number of requests currently outstanding (i.e. for which their
		253	callback has not been invoked yet).
		254
		255	Example: wait till there are no outstanding requests anymore:
		256
		257	IO::AIO::poll_wait, IO::AIO::poll_cb
		258	while IO::AIO::nreqs;
		259
		260	=item IO::AIO::flush
		261
		262	Wait till all outstanding AIO requests have been handled.
		263
		264	Strictly equivalent to:
		265
		266	IO::AIO::poll_wait, IO::AIO::poll_cb
		267	while IO::AIO::nreqs;
		268
		269	=item IO::AIO::poll
		270
		271	Waits until some requests have been handled.
		272
		273	Strictly equivalent to:
		274
		275	IO::AIO::poll_wait, IO::AIO::poll_cb
		276	if IO::AIO::nreqs;
		277
		278	=item IO::AIO::min_parallel $nthreads
		279
		280	Set the minimum number of AIO threads to C<$nthreads>. The default is
		281	C<1>, which means a single asynchronous operation can be done at one time
		282	(the number of outstanding operations, however, is unlimited).
		283
		284	It is recommended to keep the number of threads low, as some Linux
		285	kernel versions will scale negatively with the number of threads (higher
		286	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
		287	threads should be fine.
		288
		289	Under normal circumstances you don't need to call this function, as this
		290	module automatically starts some threads (the exact number might change,
		291	and is currently 4).
		292
		293	=item IO::AIO::max_parallel $nthreads
		294
		295	Sets the maximum number of AIO threads to C<$nthreads>. If more than
		296	the specified number of threads are currently running, kill them. This
		297	function blocks until the limit is reached.
		298
		299	This module automatically runs C<max_parallel 0> at program end, to ensure
		300	that all threads are killed and that there are no outstanding requests.
		301
		302	Under normal circumstances you don't need to call this function.
		303
		304	=item $oldnreqs = IO::AIO::max_outstanding $nreqs
		305
		306	Sets the maximum number of outstanding requests to C<$nreqs>. If you
		307	try to queue up more than this number of requests, the caller will block until
		308	some requests have been handled.
		309
		310	The default is very large, so normally there is no practical limit. If you
		311	queue up many requests in a loop it it often improves speed if you set
		312	this to a relatively low number, such as C<100>.
		313
		314	Under normal circumstances you don't need to call this function.
		315
		316	=back
		317
219	=cut	318	=cut
		319
		320	# support function to convert a fd into a perl filehandle
		321	sub _fd2fh {
		322	return undef if $_[0] < 0;
		323
		324	# try to generate nice filehandles
		325	my $sym = "IO::AIO::fd#$_[0]";
		326	local *$sym;
		327
		328	open *$sym, "+<&=$_[0]" # usually works under any unix
		329	or open *$sym, "<&=$_[0]" # cygwin needs this
		330	or open *$sym, ">&=$_[0]" # or this
		331	or return undef;
		332
		333	*$sym
		334	}
220		335
221	min_parallel 4;	336	min_parallel 4;
222		337
223	END {	338	END {
224	max_parallel 0;	339	max_parallel 0;
225	}	340	}
226		341
227	1;	342	1;
228		343
229	=back	344	=head2 FORK BEHAVIOUR
230		345
231	=head1 BUGS	346	IO::AIO handles all outstanding AIO requests before the fork, destroys all
		347	AIO threads, and recreates them in both the parent and the child after the
		348	fork.
232		349
233	- aio_open gives a fd, but all other functions expect a perl filehandle.
234		350
235	=head1 SEE ALSO	351	=head1 SEE ALSO
236		352
237	L<Coro>, L<Linux::AIO>.	353	L<Coro>, L<Linux::AIO>.
238		354

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.1 by root, Sun Jul 10 17:07:44 2005 UTC vs. Revision 1.27 by root, Tue Aug 16 22:22:18 2005 UTC

Diff Legend

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.1 by root, Sun Jul 10 17:07:44 2005 UTC vs.
Revision 1.27 by root, Tue Aug 16 22:22:18 2005 UTC