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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.4 by root, Sun Jul 10 20:57:00 2005 UTC vs.
Revision 1.27 by root, Tue Aug 16 22:22:18 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
		61	no warnings;
		62
49	use base 'Exporter';	63	use base 'Exporter';
50		64
51	use Fcntl ();	65	use Fcntl ();
52		66
53	BEGIN {	67	BEGIN {
54	$VERSION = 0.2;	68	$VERSION = 1.1;
55		69
56	@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
57	aio_fsync aio_fdatasync aio_readahead);	71	aio_rmdir aio_symlink aio_fsync aio_fdatasync aio_readahead);
58	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	72	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);
59		73
60	require XSLoader;	74	require XSLoader;
61	XSLoader::load IO::AIO, $VERSION;	75	XSLoader::load IO::AIO, $VERSION;
62	}	76	}
63		77
64	=item IO::AIO::min_parallel $nthreads	78	=head1 FUNCTIONS
65		79
66	Set the minimum number of AIO threads to C<$nthreads>. The default is	80	=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		81
70	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
71	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,
72	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	84	and they all accept an additional (and optional) C<$callback> argument
73	threads should be fine.	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.
74		89
75	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
76	module automatically starts some threads (the exact number might change,	91	internally until the request has finished.
77	and is currently 4).
78		92
79	=item IO::AIO::max_parallel $nthreads	93	The filenames you pass to these routines I<must> be absolute. The reason
		94	for this is that at the time the request is being executed, the current
		95	working directory could have changed. Alternatively, you can make sure
		96	that you never change the current working directory.
80		97
81	Sets the maximum number of AIO threads to C<$nthreads>. If more than	98	=over 4
82	the specified number of threads are currently running, kill them. This
83	function blocks until the limit is reached.
84
85	This module automatically runs C<max_parallel 0> at program end, to ensure
86	that all threads are killed and that there are no outstanding requests.
87
88	Under normal circumstances you don't need to call this function.
89
90	=item $oldnreqs = IO::AIO::max_outstanding $nreqs
91
92	Sets the maximum number of outstanding requests to C<$nreqs>. If you
93	try to queue up more than this number of requests, the caller will block until
94	some requests have been handled.
95
96	The default is very large, so normally there is no practical limit. If you
97	queue up many requests in a loop it it often improves speed if you set
98	this to a relatively low number, such as C<100>.
99
100	Under normal circumstances you don't need to call this function.
101
102	=item $fileno = IO::AIO::poll_fileno
103
104	Return the I<request result pipe filehandle>. This filehandle must be
105	polled for reading by some mechanism outside this module (e.g. Event
106	or select, see below). If the pipe becomes readable you have to call
107	C<poll_cb> to check the results.
108
109	See C<poll_cb> for an example.
110
111	=item IO::AIO::poll_cb
112
113	Process all outstanding events on the result pipe. You have to call this
114	regularly. Returns the number of events processed. Returns immediately
115	when no events are outstanding.
116
117	You can use Event to multiplex, e.g.:
118
119	Event->io (fd => IO::AIO::poll_fileno,
120	poll => 'r', async => 1,
121	cb => \&IO::AIO::poll_cb);
122
123	=item IO::AIO::poll_wait
124
125	Wait till the result filehandle becomes ready for reading (simply does a
126	select on the filehandle. This is useful if you want to synchronously wait
127	for some requests to finish).
128
129	See C<nreqs> for an example.
130
131	=item IO::AIO::nreqs
132
133	Returns the number of requests currently outstanding.
134
135	Example: wait till there are no outstanding requests anymore:
136
137	IO::AIO::poll_wait, IO::AIO::poll_cb
138	while IO::AIO::nreqs;
139		99
140	=item aio_open $pathname, $flags, $mode, $callback	100	=item aio_open $pathname, $flags, $mode, $callback
141		101
142	Asynchronously open or create a file and call the callback with a newly	102	Asynchronously open or create a file and call the callback with a newly
143	created filehandle for the file.	103	created filehandle for the file.
144		104
145	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	105	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
146	for an explanation.	106	for an explanation.
147		107
148	The C<$mode> argument is a bitmask. See the C<Fcntl> module for a	108	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
149	list. They are the same as used in C<sysopen>.	109	list. They are the same as used by C<sysopen>.
		110
		111	Likewise, C<$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).
150		115
151	Example:	116	Example:
152		117
153	aio_open "/etc/passwd", O_RDONLY, 0, sub {	118	aio_open "/etc/passwd", O_RDONLY, 0, sub {
154	if ($_[0]) {	119	if ($_[0]) {
…		…
161		126
162	=item aio_close $fh, $callback	127	=item aio_close $fh, $callback
163		128
164	Asynchronously close a file and call the callback with the result	129	Asynchronously close a file and call the callback with the result
165	code. I<WARNING:> although accepted, you should not pass in a perl	130	code. I<WARNING:> although accepted, you should not pass in a perl
166	filehandle here, as perl will likely close the file descriptor itself when	131	filehandle here, as perl will likely close the file descriptor another
167	the filehandle is destroyed. Normally, you can safely call perls C<close>	132	time when the filehandle is destroyed. Normally, you can safely call perls
168	or just let filehandles go out of scope.	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.
169		137
170	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback	138	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
171		139
172	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback	140	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
173		141
174	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	142	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
175	into the scalar given by C<data> and offset C<dataoffset> and calls the	143	into the scalar given by C<data> and offset C<dataoffset> and calls the
176	callback without the actual number of bytes read (or -1 on error, just	144	callback without the actual number of bytes read (or -1 on error, just
177	like the syscall).	145	like the syscall).
178		146
179	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at	147	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
180	offset C<0> within the scalar:	148	offset C<0> within the scalar:
181		149
182	aio_read $fh, 7, 15, $buffer, 0, sub {	150	aio_read $fh, 7, 15, $buffer, 0, sub {
183	$_[0] >= 0 or die "read error: $!";	151	$_[0] > 0 or die "read error: $!";
184	print "read <$buffer>\n";	152	print "read $_[0] bytes: <$buffer>\n";
185	};	153	};
186		154
187	=item aio_readahead $fh,$offset,$length, $callback	155	=item aio_readahead $fh,$offset,$length, $callback
188		156
189	Asynchronously reads the specified byte range into the page cache, using
190	the C<readahead> syscall. If that syscall doesn't exist the status will be
191	C<-1> and C<$!> is set to ENOSYS.
192
193	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
194	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>
195	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
196	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
197	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
198	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
199	(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
200	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.
201		168
202	=item aio_stat $fh_or_path, $callback	169	=item aio_stat $fh_or_path, $callback
203		170
204	=item aio_lstat $fh, $callback	171	=item aio_lstat $fh, $callback
205		172
…		…
224	=item aio_unlink $pathname, $callback	191	=item aio_unlink $pathname, $callback
225		192
226	Asynchronously unlink (delete) a file and call the callback with the	193	Asynchronously unlink (delete) a file and call the callback with the
227	result code.	194	result code.
228		195
		196	=item aio_rmdir $pathname, $callback
		197
		198	Asynchronously rmdir (delete) a directory and call the callback with the
		199	result code.
		200
229	=item aio_fsync $fh, $callback	201	=item aio_fsync $fh, $callback
230		202
231	Asynchronously call fsync on the given filehandle and call the callback	203	Asynchronously call fsync on the given filehandle and call the callback
232	with the fsync result code.	204	with the fsync result code.
233		205
234	=item aio_fdatasync $fh, $callback	206	=item aio_fdatasync $fh, $callback
235		207
236	Asynchronously call fdatasync on the given filehandle and call the	208	Asynchronously call fdatasync on the given filehandle and call the
237	callback with the fdatasync result code.	209	callback with the fdatasync result code.
		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
238		317
239	=cut	318	=cut
240		319
241	# support function to convert a fd into a perl filehandle	320	# support function to convert a fd into a perl filehandle
242	sub _fd2fh {	321	sub _fd2fh {
243	return undef if $_[0] < 0;	322	return undef if $_[0] < 0;
244		323
245	# try to be perl5.6-compatible	324	# try to generate nice filehandles
246	local *AIO_FH;	325	my $sym = "IO::AIO::fd#$_[0]";
247	open AIO_FH, "+<&=$_[0]"	326	local *$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
248	or return undef;	331	or return undef;
249		332
250	*AIO_FH	333	*$sym
251	}	334	}
252		335
253	min_parallel 4;	336	min_parallel 4;
254		337
255	END {	338	END {
256	max_parallel 0;	339	max_parallel 0;
257	}	340	}
258		341
259	1;	342	1;
260		343
261	=back	344	=head2 FORK BEHAVIOUR
262		345
263	=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.
264		349
265	- could be optimized to use more semaphores instead of filehandles.
266		350
267	=head1 SEE ALSO	351	=head1 SEE ALSO
268		352
269	L<Coro>, L<Linux::AIO>.	353	L<Coro>, L<Linux::AIO>.
270		354

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing IO-AIO/AIO.pm (file contents): Revision 1.4 by root, Sun Jul 10 20:57:00 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 1.4 by root, Sun Jul 10 20:57:00 2005 UTC vs.
Revision 1.27 by root, Tue Aug 16 22:22:18 2005 UTC