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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.2 by root, Sun Jul 10 18:16:49 2005 UTC vs.
Revision 1.22 by root, Wed Jul 20 21:55:27 2005 UTC

…		…
3	IO::AIO - Asynchronous Input/Output	3	IO::AIO - Asynchronous Input/Output
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
		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: $!";
		18	};
		19
		20	# Event
		21	Event->io (fd => IO::AIO::poll_fileno,
		22	poll => 'r',
		23	cb => \&IO::AIO::poll_cb);
		24
		25	# Glib/Gtk2
		26	add_watch Glib::IO IO::AIO::poll_fileno,
		27	in => sub { IO::AIO::poll_cb; 1 };
		28
		29	# Tk
		30	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		31	readable => \&IO::AIO::poll_cb);
		32
		33	# Danga::Socket
		34	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		35	\&IO::AIO::poll_cb);
		36
8		37
9	=head1 DESCRIPTION	38	=head1 DESCRIPTION
10		39
11	This module implements asynchronous I/O using whatever means your	40	This module implements asynchronous I/O using whatever means your
12	operating system supports.	41	operating system supports.
…		…
19	not well-supported (Linux doesn't allow them on normal files currently,	48	not well-supported (Linux doesn't allow them on normal files currently,
20	for example), and they would only support aio_read and aio_write, so the	49	for example), and they would only support aio_read and aio_write, so the
21	remaining functionality would have to be implemented using threads anyway.	50	remaining functionality would have to be implemented using threads anyway.
22		51
23	Although the module will work with in the presence of other threads, it is	52	Although the module will work with in the presence of other threads, it is
24	currently not reentrant, so use appropriate locking yourself.	53	currently not reentrant, so use appropriate locking yourself, always call
25		54	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other
26	=head2 API NOTES	55	C<aio_> functions) recursively.
27
28	All the C<aio_*> calls are more or less thin wrappers around the syscall
29	with the same name (sans C<aio_>). The arguments are similar or identical,
30	and they all accept an additional C<$callback> argument which must be
31	a code reference. This code reference will get called with the syscall
32	return code (e.g. most syscalls return C<-1> on error, unlike perl, which
33	usually delivers "false") as it's sole argument when the given syscall has
34	been executed asynchronously.
35
36	All functions that expect a filehandle will also accept a file descriptor.
37
38	The filenames you pass to these routines I<must> be absolute. The reason
39	is that at the time the request is being executed, the current working
40	directory could have changed. Alternatively, you can make sure that you
41	never change the current working directory.
42
43	=over 4
44		56
45	=cut	57	=cut
46		58
47	package IO::AIO;	59	package IO::AIO;
48		60
49	use base 'Exporter';	61	use base 'Exporter';
50		62
51	use Fcntl ();	63	use Fcntl ();
52		64
53	BEGIN {	65	BEGIN {
54	$VERSION = 0.1;	66	$VERSION = 0.9;
55		67
56	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink	68	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink
57	aio_fsync aio_fdatasync aio_readahead);	69	aio_fsync aio_fdatasync aio_readahead);
58	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs);	70	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);
59		71
60	require XSLoader;	72	require XSLoader;
61	XSLoader::load IO::AIO, $VERSION;	73	XSLoader::load IO::AIO, $VERSION;
62	}	74	}
63		75
64	=item IO::AIO::min_parallel $nthreads	76	=head1 FUNCTIONS
65		77
66	Set the minimum number of AIO threads to C<$nthreads>. The default is	78	=head2 AIO FUNCTIONS
67	C<1>, which means a single asynchronous operation can be done at one time
68	(the number of outstanding operations, however, is unlimited).
69		79
70	It is recommended to keep the number of threads low, as some linux	80	All the C<aio_*> calls are more or less thin wrappers around the syscall
71	kernel versions will scale negatively with the number of threads (higher	81	with the same name (sans C<aio_>). The arguments are similar or identical,
72	parallelity => MUCH higher latency).	82	and they all accept an additional (and optional) C<$callback> argument
		83	which must be a code reference. This code reference will get called with
		84	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
		85	perl, which usually delivers "false") as it's sole argument when the given
		86	syscall has been executed asynchronously.
73		87
74	Under normal circumstances you don't need to call this function, as this	88	All functions that expect a filehandle will also accept a file descriptor.
75	module automatically starts a single async thread.
76		89
77	=item IO::AIO::max_parallel $nthreads	90	The filenames you pass to these routines I<must> be absolute. The reason
		91	for this is that at the time the request is being executed, the current
		92	working directory could have changed. Alternatively, you can make sure
		93	that you never change the current working directory.
78		94
79	Sets the maximum number of AIO threads to C<$nthreads>. If more than	95	=over 4
80	the specified number of threads are currently running, kill them. This
81	function blocks until the limit is reached.
82
83	This module automatically runs C<max_parallel 0> at program end, to ensure
84	that all threads are killed and that there are no outstanding requests.
85
86	Under normal circumstances you don't need to call this function.
87
88	=item $fileno = IO::AIO::poll_fileno
89
90	Return the I<request result pipe filehandle>. This filehandle must be
91	polled for reading by some mechanism outside this module (e.g. Event
92	or select, see below). If the pipe becomes readable you have to call
93	C<poll_cb> to check the results.
94
95	See C<poll_cb> for an example.
96
97	=item IO::AIO::poll_cb
98
99	Process all outstanding events on the result pipe. You have to call this
100	regularly. Returns the number of events processed. Returns immediately
101	when no events are outstanding.
102
103	You can use Event to multiplex, e.g.:
104
105	Event->io (fd => IO::AIO::poll_fileno,
106	poll => 'r', async => 1,
107	cb => \&IO::AIO::poll_cb);
108
109	=item IO::AIO::poll_wait
110
111	Wait till the result filehandle becomes ready for reading (simply does a
112	select on the filehandle. This is useful if you want to synchronously wait
113	for some requests to finish).
114
115	See C<nreqs> for an example.
116
117	=item IO::AIO::nreqs
118
119	Returns the number of requests currently outstanding.
120
121	Example: wait till there are no outstanding requests anymore:
122
123	IO::AIO::poll_wait, IO::AIO::poll_cb
124	while IO::AIO::nreqs;
125		96
126	=item aio_open $pathname, $flags, $mode, $callback	97	=item aio_open $pathname, $flags, $mode, $callback
127		98
128	Asynchronously open or create a file and call the callback with a newly	99	Asynchronously open or create a file and call the callback with a newly
129	created filehandle for the file.	100	created filehandle for the file.
130		101
131	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	102	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
132	for an explanation.	103	for an explanation.
133		104
134	The C<$mode> argument is a bitmask. See the C<Fcntl> module for a	105	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
135	list. They are the same as used in C<sysopen>.	106	list. They are the same as used by C<sysopen>.
		107
		108	Likewise, C<$mode> specifies the mode of the newly created file, if it
		109	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
		110	except that it is mandatory (i.e. use C<0> if you don't create new files,
		111	and C<0666> or C<0777> if you do).
136		112
137	Example:	113	Example:
138		114
139	aio_open "/etc/passwd", O_RDONLY, 0, sub {	115	aio_open "/etc/passwd", O_RDONLY, 0, sub {
140	if ($_[0]) {	116	if ($_[0]) {
…		…
147		123
148	=item aio_close $fh, $callback	124	=item aio_close $fh, $callback
149		125
150	Asynchronously close a file and call the callback with the result	126	Asynchronously close a file and call the callback with the result
151	code. I<WARNING:> although accepted, you should not pass in a perl	127	code. I<WARNING:> although accepted, you should not pass in a perl
152	filehandle here, as perl will likely close the file descriptor itself when	128	filehandle here, as perl will likely close the file descriptor another
153	the filehandle is destroyed. Normally, you can safely call perls C<close>	129	time when the filehandle is destroyed. Normally, you can safely call perls
154	or just let filehandles go out of scope.	130	C<close> or just let filehandles go out of scope.
		131
		132	This is supposed to be a bug in the API, so that might change. It's
		133	therefore best to avoid this function.
155		134
156	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback	135	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
157		136
158	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback	137	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
159		138
160	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	139	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
161	into the scalar given by C<data> and offset C<dataoffset> and calls the	140	into the scalar given by C<data> and offset C<dataoffset> and calls the
162	callback without the actual number of bytes read (or -1 on error, just	141	callback without the actual number of bytes read (or -1 on error, just
163	like the syscall).	142	like the syscall).
164		143
165	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at	144	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
166	offset C<0> within the scalar:	145	offset C<0> within the scalar:
167		146
168	aio_read $fh, 7, 15, $buffer, 0, sub {	147	aio_read $fh, 7, 15, $buffer, 0, sub {
169	$_[0] >= 0 or die "read error: $!";	148	$_[0] > 0 or die "read error: $!";
170	print "read <$buffer>\n";	149	print "read $_[0] bytes: <$buffer>\n";
171	};	150	};
172		151
173	=item aio_readahead $fh,$offset,$length, $callback	152	=item aio_readahead $fh,$offset,$length, $callback
174		153
175	Asynchronously reads the specified byte range into the page cache, using	154	Asynchronously reads the specified byte range into the page cache, using
176	the C<readahead> syscall. If that syscall doesn't exist the status will be	155	the C<readahead> syscall. If that syscall doesn't exist (likely if your OS
177	C<-1> and C<$!> is set to ENOSYS.	156	isn't Linux) the status will be C<-1> and C<$!> is set to C<ENOSYS>.
178		157
179	readahead() populates the page cache with data from a file so that	158	C<aio_readahead> populates the page cache with data from a file so that
180	subsequent reads from that file will not block on disk I/O. The C<$offset>	159	subsequent reads from that file will not block on disk I/O. The C<$offset>
181	argument specifies the starting point from which data is to be read and	160	argument specifies the starting point from which data is to be read and
182	C<$length> specifies the number of bytes to be read. I/O is performed in	161	C<$length> specifies the number of bytes to be read. I/O is performed in
183	whole pages, so that offset is effectively rounded down to a page boundary	162	whole pages, so that offset is effectively rounded down to a page boundary
184	and bytes are read up to the next page boundary greater than or equal to	163	and bytes are read up to the next page boundary greater than or equal to
185	(off-set+length). aio_readahead() does not read beyond the end of the	164	(off-set+length). C<aio_readahead> does not read beyond the end of the
186	file. The current file offset of the file is left unchanged.	165	file. The current file offset of the file is left unchanged.
187		166
188	=item aio_stat $fh_or_path, $callback	167	=item aio_stat $fh_or_path, $callback
189		168
190	=item aio_lstat $fh, $callback	169	=item aio_lstat $fh, $callback
…		…
218	with the fsync result code.	197	with the fsync result code.
219		198
220	=item aio_fdatasync $fh, $callback	199	=item aio_fdatasync $fh, $callback
221		200
222	Asynchronously call fdatasync on the given filehandle and call the	201	Asynchronously call fdatasync on the given filehandle and call the
223	callback with the fdatasync result code.	202	callback with the fdatasync result code. Might set C<$!> to C<ENOSYS> if
		203	C<fdatasync> is not available.
		204
		205	=back
		206
		207	=head2 SUPPORT FUNCTIONS
		208
		209	=over 4
		210
		211	=item $fileno = IO::AIO::poll_fileno
		212
		213	Return the I<request result pipe file descriptor>. This filehandle must be
		214	polled for reading by some mechanism outside this module (e.g. Event or
		215	select, see below or the SYNOPSIS). If the pipe becomes readable you have
		216	to call C<poll_cb> to check the results.
		217
		218	See C<poll_cb> for an example.
		219
		220	=item IO::AIO::poll_cb
		221
		222	Process all outstanding events on the result pipe. You have to call this
		223	regularly. Returns the number of events processed. Returns immediately
		224	when no events are outstanding.
		225
		226	Example: Install an Event watcher that automatically calls
		227	IO::AIO::poll_cb with high priority:
		228
		229	Event->io (fd => IO::AIO::poll_fileno,
		230	poll => 'r', async => 1,
		231	cb => \&IO::AIO::poll_cb);
		232
		233	=item IO::AIO::poll_wait
		234
		235	Wait till the result filehandle becomes ready for reading (simply does a
		236	C<select> on the filehandle. This is useful if you want to synchronously wait
		237	for some requests to finish).
		238
		239	See C<nreqs> for an example.
		240
		241	=item IO::AIO::nreqs
		242
		243	Returns the number of requests currently outstanding (i.e. for which their
		244	callback has not been invoked yet).
		245
		246	Example: wait till there are no outstanding requests anymore:
		247
		248	IO::AIO::poll_wait, IO::AIO::poll_cb
		249	while IO::AIO::nreqs;
		250
		251	=item IO::AIO::flush
		252
		253	Wait till all outstanding AIO requests have been handled.
		254
		255	Strictly equivalent to:
		256
		257	IO::AIO::poll_wait, IO::AIO::poll_cb
		258	while IO::AIO::nreqs;
		259
		260	=item IO::AIO::poll
		261
		262	Waits until some requests have been handled.
		263
		264	Strictly equivalent to:
		265
		266	IO::AIO::poll_wait, IO::AIO::poll_cb
		267	if IO::AIO::nreqs;
		268
		269	=item IO::AIO::min_parallel $nthreads
		270
		271	Set the minimum number of AIO threads to C<$nthreads>. The default is
		272	C<1>, which means a single asynchronous operation can be done at one time
		273	(the number of outstanding operations, however, is unlimited).
		274
		275	It is recommended to keep the number of threads low, as some Linux
		276	kernel versions will scale negatively with the number of threads (higher
		277	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
		278	threads should be fine.
		279
		280	Under normal circumstances you don't need to call this function, as this
		281	module automatically starts some threads (the exact number might change,
		282	and is currently 4).
		283
		284	=item IO::AIO::max_parallel $nthreads
		285
		286	Sets the maximum number of AIO threads to C<$nthreads>. If more than
		287	the specified number of threads are currently running, kill them. This
		288	function blocks until the limit is reached.
		289
		290	This module automatically runs C<max_parallel 0> at program end, to ensure
		291	that all threads are killed and that there are no outstanding requests.
		292
		293	Under normal circumstances you don't need to call this function.
		294
		295	=item $oldnreqs = IO::AIO::max_outstanding $nreqs
		296
		297	Sets the maximum number of outstanding requests to C<$nreqs>. If you
		298	try to queue up more than this number of requests, the caller will block until
		299	some requests have been handled.
		300
		301	The default is very large, so normally there is no practical limit. If you
		302	queue up many requests in a loop it it often improves speed if you set
		303	this to a relatively low number, such as C<100>.
		304
		305	Under normal circumstances you don't need to call this function.
		306
		307	=back
224		308
225	=cut	309	=cut
226		310
227	# support function to convert a fd into a perl filehandle	311	# support function to convert a fd into a perl filehandle
228	sub _fd2fh {	312	sub _fd2fh {
…		…
242	max_parallel 0;	326	max_parallel 0;
243	}	327	}
244		328
245	1;	329	1;
246		330
247	=back
248
249	=head1 BUGS
250
251	- could be optimized to use more semaphores instead of filehandles.
252
253	=head1 SEE ALSO	331	=head1 SEE ALSO
254		332
255	L<Coro>, L<Linux::AIO>.	333	L<Coro>, L<Linux::AIO>.
256		334
257	=head1 AUTHOR	335	=head1 AUTHOR

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.2 by root, Sun Jul 10 18:16:49 2005 UTC vs. Revision 1.22 by root, Wed Jul 20 21:55:27 2005 UTC

Diff Legend

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.2 by root, Sun Jul 10 18:16:49 2005 UTC vs.
Revision 1.22 by root, Wed Jul 20 21:55:27 2005 UTC