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

Comparing Linux-AIO/AIO.pm (file contents):
Revision 1.15 by root, Thu May 6 12:16:48 2004 UTC vs.
Revision 1.31 by root, Sun Jul 10 01:03:06 2005 UTC

…		…
6		6
7	use Linux::AIO;	7	use Linux::AIO;
8		8
9	=head1 DESCRIPTION	9	=head1 DESCRIPTION
10		10
11	This module implements asynchronous i/o using the means available to linux	11	This module implements asynchronous I/O using the means available to Linux
12	- clone. It does not hook into the POSIX aio_* functions because linux	12	- clone. It does not hook into the POSIX aio_* functions because Linux
13	does not yet support these in the kernel (and even if, it would only allow	13	does not yet support these in the kernel (even as of 2.6.12, only O_DIRECT
14	aio_read and write, not open and stat).	14	files are supported) and even if, it would only allow aio_read and write,
		15	not open, stat and so on.
15		16
16	Instead, in this module a number of (non-posix) threads are started that	17	Instead, in this module a number of (non-posix) threads are started that
17	execute your read/writes and signal their completion. You don't need	18	execute your read/writes and signal their completion. You don't need
18	thread support in your libc or perl, and the threads created by this	19	thread support in your libc or perl, and the threads created by this
19	module will not be visible to the pthreads library.	20	module will not be visible to the pthreads library.
20		21
		22	NOTICE: the threads created by this module will automatically be killed
		23	when the thread calling min_parallel exits. Make sure you only ever call
		24	min_parallel from the same thread that loaded this module.
		25
		26	Although the module will work with in the presence of other threads, it is
		27	not reentrant, so use appropriate locking yourself.
		28
		29	=head2 API NOTES
		30
		31	All the C<aio_*> calls are more or less thin wrappers around the syscall
		32	with the same name (sans C<aio_>). The arguments are similar or identical,
		33	and they all accept an additional C<$callback> argument which must be
		34	a code reference. This code reference will get called with the syscall
		35	return code (e.g. most syscalls return C<-1> on error, unlike perl, which
		36	usually delivers "false") as it's sole argument when the given syscall has
		37	been executed asynchronously.
		38
		39	All functions that expect a filehandle will also accept a file descriptor.
		40
21	=over 4	41	=over 4
22		42
23	=cut	43	=cut
24		44
25	package Linux::AIO;	45	package Linux::AIO;
26		46
27	use base 'Exporter';	47	use base 'Exporter';
28		48
29	BEGIN {	49	BEGIN {
30	$VERSION = 1.01;	50	$VERSION = 1.71;
31		51
32	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat);	52	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink
		53	aio_fsync aio_fdatasync aio_readahead);
33	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs);	54	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs);
34		55
35	require XSLoader;	56	require XSLoader;
36	XSLoader::load Linux::AIO, $VERSION;	57	XSLoader::load Linux::AIO, $VERSION;
37	}	58	}
38		59
39	=item Linux::AIO::min_parallel $nthreads	60	=item Linux::AIO::min_parallel $nthreads
40		61
41	Set the minimum number of AIO threads to C<$nthreads>. You I<have> to call	62	Set the minimum number of AIO threads to C<$nthreads>. The default is
42	this function with a positive number at least once, otherwise no threads	63	C<1>, which means a single asynchronous operation can be done at one time
43	will be started and you aio-operations will seem to hang.	64	(the number of outstanding operations, however, is unlimited).
44		65
45	It is recommended to keep the number of threads low, as many linux	66	It is recommended to keep the number of threads low, as some linux
46	kernel versions will scale negatively with the number of threads (higher	67	kernel versions will scale negatively with the number of threads (higher
47	parallelity => MUCH higher latency).	68	parallelity => MUCH higher latency).
		69
		70	Under normal circumstances you don't need to call this function, as this
		71	module automatically starts a single async thread.
		72
		73	=item Linux::AIO::max_parallel $nthreads
		74
		75	Sets the maximum number of AIO threads to C<$nthreads>. If more than
		76	the specified number of threads are currently running, kill them. This
		77	function blocks until the limit is reached.
		78
		79	This module automatically runs C<max_parallel 0> at program end, to ensure
		80	that all threads are killed and that there are no outstanding requests.
		81
		82	Under normal circumstances you don't need to call this function.
48		83
49	=item $fileno = Linux::AIO::poll_fileno	84	=item $fileno = Linux::AIO::poll_fileno
50		85
51	Return the I<request result pipe filehandle>. This filehandle must be	86	Return the I<request result pipe filehandle>. This filehandle must be
52	polled for reading by some mechanism outside this module (e.g. Event	87	polled for reading by some mechanism outside this module (e.g. Event
53	or select, see below). If the pipe becomes readable you have to call	88	or select, see below). If the pipe becomes readable you have to call
54	C<poll_cb> to check the results.	89	C<poll_cb> to check the results.
55		90
		91	See C<poll_cb> for an example.
		92
56	=item Linux::AIO::poll_cb	93	=item Linux::AIO::poll_cb
57		94
58	Process all outstanding events on the result pipe. You have to call this	95	Process all outstanding events on the result pipe. You have to call this
59	regularly. Returns the number of events processed. Returns immediately	96	regularly. Returns the number of events processed. Returns immediately
60	when no events are outstanding.	97	when no events are outstanding.
61		98
62	You can use Event to multiplex, e.g.:	99	You can use Event to multiplex, e.g.:
63		100
64	Event->io (fd => Linux::AIO::poll_fileno,	101	Event->io (fd => Linux::AIO::poll_fileno,
65	poll => 'r', async => 1,	102	poll => 'r', async => 1,
66	cb => \&Linux::AIO::poll_cb );	103	cb => \&Linux::AIO::poll_cb);
67		104
		105	=item Linux::AIO::poll_wait
		106
		107	Wait till the result filehandle becomes ready for reading (simply does a
		108	select on the filehandle. This is useful if you want to synchronously wait
		109	for some requests to finish).
		110
		111	See C<nreqs> for an example.
68		112
69	=item Linux::AIO::nreqs	113	=item Linux::AIO::nreqs
70		114
71	Returns the number of requests currently outstanding.	115	Returns the number of requests currently outstanding.
72		116
		117	Example: wait till there are no outstanding requests anymore:
		118
		119	Linux::AIO::poll_wait while Linux::AIO::nreqs;
		120
73	=item aio_open $pathname, $flags, $mode, $callback	121	=item aio_open $pathname, $flags, $mode, $callback
74		122
75	Asynchronously open or create a file and call the callback with the	123	Asynchronously open or create a file and call the callback with the
76	filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this	124	filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this
77	might change in the future).	125	might change in the future).
78		126
		127	The C<$mode> argument is a bitmask. See the C<Fcntl> module for a
		128	list. They are the same as used in C<sysopen>.
		129
		130	Example:
		131
		132	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		133	if ($_[0] >= 0) {
		134	open my $fh, "<&$_[0]"; # create a copy for perl
		135	aio_close $_[0], sub { }; # close the aio handle
		136	print "open successful, fh is $fh\n";
		137	...
		138	} else {
		139	die "open failed: $!\n";
		140	}
		141	};
		142
79	=item aio_close $fh, $callback	143	=item aio_close $fh, $callback
80		144
81	Asynchronously close a file and call the callback with the result code.	145	Asynchronously close a file and call the callback with the result code.
82		146
83	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback	147	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
84		148
85	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback	149	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
86		150
87	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	151	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
88	into the scalar given by C<data> and offset C<dataoffset> and calls the	152	into the scalar given by C<data> and offset C<dataoffset> and calls the
89	callback without the actual number of bytes read (or C<undef> on error).	153	callback without the actual number of bytes read (or -1 on error, just
		154	like the syscall).
		155
		156	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at
		157	offset C<0> within the scalar:
		158
		159	aio_read $fh, 7, 15, $buffer, 0, sub {
		160	$_[0] >= 0 or die "read error: $!";
		161	print "read <$buffer>\n";
		162	};
		163
		164	=item aio_readahead $fh,$offset,$length, $callback
		165
		166	Asynchronously reads the specified byte range into the page cache, using
		167	the C<readahead> syscall.
		168
		169	readahead() populates the page cache with data from a file so that
		170	subsequent reads from that file will not block on disk I/O. The C<$offset>
		171	argument specifies the starting point from which data is to be read and
		172	C<$length> specifies the number of bytes to be read. I/O is performed in
		173	whole pages, so that offset is effectively rounded down to a page boundary
		174	and bytes are read up to the next page boundary greater than or equal to
		175	(off-set+length). aio_readahead() does not read beyond the end of the
		176	file. The current file offset of the file is left unchanged.
90		177
91	=item aio_stat $fh_or_path, $callback	178	=item aio_stat $fh_or_path, $callback
92		179
93	=item aio_lstat $fh, $callback	180	=item aio_lstat $fh, $callback
94		181
…		…
98		185
99	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	186	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
100	error when stat'ing a large file, the results will be silently truncated	187	error when stat'ing a large file, the results will be silently truncated
101	unless perl itself is compiled with large file support.	188	unless perl itself is compiled with large file support.
102		189
		190	Example: Print the length of F</etc/passwd>:
		191
		192	aio_stat "/etc/passwd", sub {
		193	$_[0] and die "stat failed: $!";
		194	print "size is ", -s _, "\n";
		195	};
		196
		197	=item aio_unlink $pathname, $callback
		198
		199	Asynchronously unlink (delete) a file and call the callback with the
		200	result code.
		201
		202	=item aio_fsync $fh, $callback
		203
		204	Asynchronously call fsync on the given filehandle and call the callback
		205	with the fsync result code.
		206
		207	=item aio_fdatasync $fh, $callback
		208
		209	Asynchronously call fdatasync on the given filehandle and call the
		210	callback with the fdatasync result code.
		211
103	=cut	212	=cut
		213
		214	min_parallel 1;
104		215
105	END {	216	END {
106	max_parallel 0;	217	max_parallel 0;
107	}	218	}
108		219
…		…
121		232
122	L<Coro>.	233	L<Coro>.
123		234
124	=head1 AUTHOR	235	=head1 AUTHOR
125		236
126	Marc Lehmann <pcg@goof.com>	237	Marc Lehmann <schmorp@schmorp.de>
127	http://www.goof.com/pcg/marc/	238	http://home.schmorp.de/
128		239
129	=cut	240	=cut
130		241

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Comparing Linux-AIO/AIO.pm (file contents): Revision 1.15 by root, Thu May 6 12:16:48 2004 UTC vs. Revision 1.31 by root, Sun Jul 10 01:03:06 2005 UTC

Diff Legend

Comparing Linux-AIO/AIO.pm (file contents):
Revision 1.15 by root, Thu May 6 12:16:48 2004 UTC vs.
Revision 1.31 by root, Sun Jul 10 01:03:06 2005 UTC