[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 1.26 by root, Sun Aug 7 03:34:07 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_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
…		…
234	=item aio_fdatasync $fh, $callback	201	=item aio_fdatasync $fh, $callback
235		202
236	Asynchronously call fdatasync on the given filehandle and call the	203	Asynchronously call fdatasync on the given filehandle and call the
237	callback with the fdatasync result code.	204	callback with the fdatasync result code.
238		205
		206	If this call isn't available because your OS lacks it or it couldn't be
		207	detected, it will be emulated by calling C<fsync> instead.
		208
		209	=back
		210
		211	=head2 SUPPORT FUNCTIONS
		212
		213	=over 4
		214
		215	=item $fileno = IO::AIO::poll_fileno
		216
		217	Return the I<request result pipe file descriptor>. This filehandle must be
		218	polled for reading by some mechanism outside this module (e.g. Event or
		219	select, see below or the SYNOPSIS). If the pipe becomes readable you have
		220	to call C<poll_cb> to check the results.
		221
		222	See C<poll_cb> for an example.
		223
		224	=item IO::AIO::poll_cb
		225
		226	Process all outstanding events on the result pipe. You have to call this
		227	regularly. Returns the number of events processed. Returns immediately
		228	when no events are outstanding.
		229
		230	Example: Install an Event watcher that automatically calls
		231	IO::AIO::poll_cb with high priority:
		232
		233	Event->io (fd => IO::AIO::poll_fileno,
		234	poll => 'r', async => 1,
		235	cb => \&IO::AIO::poll_cb);
		236
		237	=item IO::AIO::poll_wait
		238
		239	Wait till the result filehandle becomes ready for reading (simply does a
		240	C<select> on the filehandle. This is useful if you want to synchronously wait
		241	for some requests to finish).
		242
		243	See C<nreqs> for an example.
		244
		245	=item IO::AIO::nreqs
		246
		247	Returns the number of requests currently outstanding (i.e. for which their
		248	callback has not been invoked yet).
		249
		250	Example: wait till there are no outstanding requests anymore:
		251
		252	IO::AIO::poll_wait, IO::AIO::poll_cb
		253	while IO::AIO::nreqs;
		254
		255	=item IO::AIO::flush
		256
		257	Wait till all outstanding AIO requests have been handled.
		258
		259	Strictly equivalent to:
		260
		261	IO::AIO::poll_wait, IO::AIO::poll_cb
		262	while IO::AIO::nreqs;
		263
		264	=item IO::AIO::poll
		265
		266	Waits until some requests have been handled.
		267
		268	Strictly equivalent to:
		269
		270	IO::AIO::poll_wait, IO::AIO::poll_cb
		271	if IO::AIO::nreqs;
		272
		273	=item IO::AIO::min_parallel $nthreads
		274
		275	Set the minimum number of AIO threads to C<$nthreads>. The default is
		276	C<1>, which means a single asynchronous operation can be done at one time
		277	(the number of outstanding operations, however, is unlimited).
		278
		279	It is recommended to keep the number of threads low, as some Linux
		280	kernel versions will scale negatively with the number of threads (higher
		281	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
		282	threads should be fine.
		283
		284	Under normal circumstances you don't need to call this function, as this
		285	module automatically starts some threads (the exact number might change,
		286	and is currently 4).
		287
		288	=item IO::AIO::max_parallel $nthreads
		289
		290	Sets the maximum number of AIO threads to C<$nthreads>. If more than
		291	the specified number of threads are currently running, kill them. This
		292	function blocks until the limit is reached.
		293
		294	This module automatically runs C<max_parallel 0> at program end, to ensure
		295	that all threads are killed and that there are no outstanding requests.
		296
		297	Under normal circumstances you don't need to call this function.
		298
		299	=item $oldnreqs = IO::AIO::max_outstanding $nreqs
		300
		301	Sets the maximum number of outstanding requests to C<$nreqs>. If you
		302	try to queue up more than this number of requests, the caller will block until
		303	some requests have been handled.
		304
		305	The default is very large, so normally there is no practical limit. If you
		306	queue up many requests in a loop it it often improves speed if you set
		307	this to a relatively low number, such as C<100>.
		308
		309	Under normal circumstances you don't need to call this function.
		310
		311	=back
		312
239	=cut	313	=cut
240		314
241	# support function to convert a fd into a perl filehandle	315	# support function to convert a fd into a perl filehandle
242	sub _fd2fh {	316	sub _fd2fh {
243	return undef if $_[0] < 0;	317	return undef if $_[0] < 0;
244		318
245	# try to be perl5.6-compatible	319	# try to generate nice filehandles
246	local *AIO_FH;	320	my $sym = "IO::AIO::fd#$_[0]";
247	open AIO_FH, "+<&=$_[0]"	321	local *$sym;
		322
		323	open *$sym, "+<&$_[0]" # usually under any unix
		324	or open *$sym, "<&$_[0]" # cygwin needs this
		325	or open *$sym, ">&$_[0]" # cygwin needs this
248	or return undef;	326	or return undef;
249		327
250	*AIO_FH	328	*$sym
251	}	329	}
252		330
253	min_parallel 4;	331	min_parallel 4;
254		332
255	END {	333	END {
256	max_parallel 0;	334	max_parallel 0;
257	}	335	}
258		336
259	1;	337	1;
260		338
261	=back
262
263	=head1 BUGS
264
265	- could be optimized to use more semaphores instead of filehandles.
266
267	=head1 SEE ALSO	339	=head1 SEE ALSO
268		340
269	L<Coro>, L<Linux::AIO>.	341	L<Coro>, L<Linux::AIO>.
270		342
271	=head1 AUTHOR	343	=head1 AUTHOR

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.4 by root, Sun Jul 10 20:57:00 2005 UTC vs. Revision 1.26 by root, Sun Aug 7 03:34:07 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 1.26 by root, Sun Aug 7 03:34:07 2005 UTC