[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 1.27 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 = 0.1;	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 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).	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.
73		89
74	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
75	module automatically starts a single async thread.	91	internally until the request has finished.
76		92
77	=item IO::AIO::max_parallel $nthreads	93	The filenames you pass to these routines I<must> be absolute. The reason
		94	for this is that at the time the request is being executed, the current
		95	working directory could have changed. Alternatively, you can make sure
		96	that you never change the current working directory.
78		97
79	Sets the maximum number of AIO threads to C<$nthreads>. If more than	98	=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		99
126	=item aio_open $pathname, $flags, $mode, $callback	100	=item aio_open $pathname, $flags, $mode, $callback
127		101
128	Asynchronously open or create a file and call the callback with a newly	102	Asynchronously open or create a file and call the callback with a newly
129	created filehandle for the file.	103	created filehandle for the file.
130		104
131	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	105	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
132	for an explanation.	106	for an explanation.
133		107
134	The C<$mode> argument is a bitmask. See the C<Fcntl> module for a	108	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
135	list. They are the same as used in C<sysopen>.	109	list. They are the same as used by C<sysopen>.
		110
		111	Likewise, C<$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).
136		115
137	Example:	116	Example:
138		117
139	aio_open "/etc/passwd", O_RDONLY, 0, sub {	118	aio_open "/etc/passwd", O_RDONLY, 0, sub {
140	if ($_[0]) {	119	if ($_[0]) {
…		…
147		126
148	=item aio_close $fh, $callback	127	=item aio_close $fh, $callback
149		128
150	Asynchronously close a file and call the callback with the result	129	Asynchronously close a file and call the callback with the result
151	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
152	filehandle here, as perl will likely close the file descriptor itself when	131	filehandle here, as perl will likely close the file descriptor another
153	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
154	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.
155		137
156	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback	138	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
157		139
158	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback	140	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
159		141
160	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	142	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
161	into the scalar given by C<data> and offset C<dataoffset> and calls the	143	into the scalar given by C<data> and offset C<dataoffset> and calls the
162	callback without the actual number of bytes read (or -1 on error, just	144	callback without the actual number of bytes read (or -1 on error, just
163	like the syscall).	145	like the syscall).
164		146
165	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at	147	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
166	offset C<0> within the scalar:	148	offset C<0> within the scalar:
167		149
168	aio_read $fh, 7, 15, $buffer, 0, sub {	150	aio_read $fh, 7, 15, $buffer, 0, sub {
169	$_[0] >= 0 or die "read error: $!";	151	$_[0] > 0 or die "read error: $!";
170	print "read <$buffer>\n";	152	print "read $_[0] bytes: <$buffer>\n";
171	};	153	};
172		154
173	=item aio_readahead $fh,$offset,$length, $callback	155	=item aio_readahead $fh,$offset,$length, $callback
174		156
175	Asynchronously reads the specified byte range into the page cache, using
176	the C<readahead> syscall. If that syscall doesn't exist the status will be
177	C<-1> and C<$!> is set to ENOSYS.
178
179	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
180	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>
181	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
182	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
183	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
184	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
185	(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
186	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.
187		168
188	=item aio_stat $fh_or_path, $callback	169	=item aio_stat $fh_or_path, $callback
189		170
190	=item aio_lstat $fh, $callback	171	=item aio_lstat $fh, $callback
191		172
…		…
210	=item aio_unlink $pathname, $callback	191	=item aio_unlink $pathname, $callback
211		192
212	Asynchronously unlink (delete) a file and call the callback with the	193	Asynchronously unlink (delete) a file and call the callback with the
213	result code.	194	result code.
214		195
		196	=item aio_rmdir $pathname, $callback
		197
		198	Asynchronously rmdir (delete) a directory and call the callback with the
		199	result code.
		200
215	=item aio_fsync $fh, $callback	201	=item aio_fsync $fh, $callback
216		202
217	Asynchronously call fsync on the given filehandle and call the callback	203	Asynchronously call fsync on the given filehandle and call the callback
218	with the fsync result code.	204	with the fsync result code.
219		205
220	=item aio_fdatasync $fh, $callback	206	=item aio_fdatasync $fh, $callback
221		207
222	Asynchronously call fdatasync on the given filehandle and call the	208	Asynchronously call fdatasync on the given filehandle and call the
223	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
224		317
225	=cut	318	=cut
226		319
227	# support function to convert a fd into a perl filehandle	320	# support function to convert a fd into a perl filehandle
228	sub _fd2fh {	321	sub _fd2fh {
229	return undef if $_[0] < 0;	322	return undef if $_[0] < 0;
230		323
231	# try to be perl5.6-compatible	324	# try to generate nice filehandles
232	local *AIO_FH;	325	my $sym = "IO::AIO::fd#$_[0]";
233	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
234	or return undef;	331	or return undef;
235		332
236	*AIO_FH	333	*$sym
237	}	334	}
238		335
239	min_parallel 4;	336	min_parallel 4;
240		337
241	END {	338	END {
242	max_parallel 0;	339	max_parallel 0;
243	}	340	}
244		341
245	1;	342	1;
246		343
247	=back	344	=head2 FORK BEHAVIOUR
248		345
249	=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.
250		349
251	- could be optimized to use more semaphores instead of filehandles.
252		350
253	=head1 SEE ALSO	351	=head1 SEE ALSO
254		352
255	L<Coro>, L<Linux::AIO>.	353	L<Coro>, L<Linux::AIO>.
256		354

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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 1.27 by root, Tue Aug 16 22:22:18 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 1.27 by root, Tue Aug 16 22:22:18 2005 UTC