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

Comparing Linux-AIO/AIO.pm (file contents):
Revision 1.3 by root, Tue Aug 14 23:25:39 2001 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 asynchroneous i/o using the means available to	11	This module implements asynchronous I/O using the means available to Linux
12	linux - clone. It does not hook into the POSIX aio_* functions because	12	- clone. It does not hook into the POSIX aio_* functions because Linux
13	linux does not yet support these in the kernel. Instead, a number of	13	does not yet support these in the kernel (even as of 2.6.12, only O_DIRECT
14	threads are started that execute your read/writes and signal their	14	files are supported) and even if, it would only allow aio_read and write,
15	completion.	15	not open, stat and so on.
		16
		17	Instead, in this module a number of (non-posix) threads are started that
		18	execute your read/writes and signal their completion. You don't need
		19	thread support in your libc or perl, and the threads created by this
		20	module will not be visible to the pthreads library.
		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.
16		40
17	=over 4	41	=over 4
18		42
19	=cut	43	=cut
20		44
21	package Linux::AIO;	45	package Linux::AIO;
22		46
23	use base 'Exporter';	47	use base 'Exporter';
24		48
25	BEGIN {	49	BEGIN {
26	$VERSION = 0.001;	50	$VERSION = 1.71;
27		51
28	@EXPORT = qw(aio_read aio_write);	52	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink
		53	aio_fsync aio_fdatasync aio_readahead);
29	@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);
30		55
31	require XSLoader;	56	require XSLoader;
32	XSLoader::load Linux::AIO, $VERSION;	57	XSLoader::load Linux::AIO, $VERSION;
33	}	58	}
34		59
35	=item Linux::AIO::min_parallel($nthreads)	60	=item Linux::AIO::min_parallel $nthreads
36		61
37	Set the minimum number of AIO threads to $nthreads. You I<have> to call	62	Set the minimum number of AIO threads to C<$nthreads>. The default is
38	this function with a positive number at leats once, otherwise no threads	63	C<1>, which means a single asynchronous operation can be done at one time
39	will be started and you aio-operations will seem to hang.	64	(the number of outstanding operations, however, is unlimited).
40		65
41	=cut	66	It is recommended to keep the number of threads low, as some linux
		67	kernel versions will scale negatively with the number of threads (higher
		68	parallelity => MUCH higher latency).
42		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.
		83
		84	=item $fileno = Linux::AIO::poll_fileno
		85
		86	Return the I<request result pipe filehandle>. This filehandle must be
		87	polled for reading by some mechanism outside this module (e.g. Event
		88	or select, see below). If the pipe becomes readable you have to call
		89	C<poll_cb> to check the results.
		90
		91	See C<poll_cb> for an example.
		92
		93	=item Linux::AIO::poll_cb
		94
		95	Process all outstanding events on the result pipe. You have to call this
		96	regularly. Returns the number of events processed. Returns immediately
		97	when no events are outstanding.
		98
		99	You can use Event to multiplex, e.g.:
		100
		101	Event->io (fd => Linux::AIO::poll_fileno,
		102	poll => 'r', async => 1,
		103	cb => \&Linux::AIO::poll_cb);
		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.
		112
		113	=item Linux::AIO::nreqs
		114
		115	Returns the number of requests currently outstanding.
		116
		117	Example: wait till there are no outstanding requests anymore:
		118
		119	Linux::AIO::poll_wait while Linux::AIO::nreqs;
		120
		121	=item aio_open $pathname, $flags, $mode, $callback
		122
		123	Asynchronously open or create a file and call the callback with the
		124	filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this
		125	might change in the future).
		126
		127	The C<$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
		143	=item aio_close $fh, $callback
		144
		145	Asynchronously close a file and call the callback with the result code.
		146
43	=item aio_read($fh,$offset,$length, $data,$dataoffset,$callback)	147	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
		148
44	aio_write($fh,$offset,$length, $data,$dataoffset,$callback)	149	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
45		150
46	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>
47	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
48	callback without the actual number of bytes read (or undef on error).	153	callback without the actual number of bytes read (or -1 on error, just
		154	like the syscall).
49		155
50	=item $fileno = Linux::AIO::poll_fileno	156	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at
		157	offset C<0> within the scalar:
51		158
52	Return the request result pipe filehandle. This filehandle must be polled	159	aio_read $fh, 7, 15, $buffer, 0, sub {
53	for reading. If the pipe becomes readable you have to call C<poll_cb>.	160	$_[0] >= 0 or die "read error: $!";
		161	print "read <$buffer>\n";
		162	};
54		163
55	=item Linux::AIO::poll_cb	164	=item aio_readahead $fh,$offset,$length, $callback
56		165
57	Process all outstanding events on the result pipe. You have to call this	166	Asynchronously reads the specified byte range into the page cache, using
58	regularly. Returns the number of events processed.	167	the C<readahead> syscall.
59		168
60	You can use Event to multiplex, e.g.:	169	readahead() populates the page cache with data from a file so that
		170	subsequent reads from that file will not block on disk I/O. The C<$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.
61		177
62	Event->io(fd => Linux::AIO::poll_fileno,	178	=item aio_stat $fh_or_path, $callback
63	poll => 'r', async => 1,
64	cb => \&Linux::AIO::poll_cb );
65		179
		180	=item aio_lstat $fh, $callback
66		181
67	=item Linux::AIO::nreqs	182	Works like perl's C<stat> or C<lstat> in void context. The callback will
		183	be called after the stat and the results will be available using C<stat _>
		184	or C<-s _> etc...
68		185
69	Returns the number of requests currently outstanding.	186	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
		187	error when stat'ing a large file, the results will be silently truncated
		188	unless perl itself is compiled with large file support.
		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.
70		211
71	=cut	212	=cut
		213
		214	min_parallel 1;
72		215
73	END {	216	END {
74	max_parallel 0;	217	max_parallel 0;
75	}	218	}
76		219
…		…
78		221
79	=back	222	=back
80		223
81	=head1 BUGS	224	=head1 BUGS
82		225
83	This module has not yet been extensively tested. Watch out!	226	This module has been extensively tested in a large and very busy webserver
		227	for many years now.
		228
		229	- aio_open gives a fd, but all other functions expect a perl filehandle.
84		230
85	=head1 SEE ALSO	231	=head1 SEE ALSO
86		232
87	L<Coro>.	233	L<Coro>.
88		234
89	=head1 AUTHOR	235	=head1 AUTHOR
90		236
91	Marc Lehmann <pcg@goof.com>	237	Marc Lehmann <schmorp@schmorp.de>
92	http://www.goof.com/pcg/marc/	238	http://home.schmorp.de/
93		239
94	=cut	240	=cut
95		241

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Comparing Linux-AIO/AIO.pm (file contents): Revision 1.3 by root, Tue Aug 14 23:25:39 2001 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 1.3 by root, Tue Aug 14 23:25:39 2001 UTC vs.
Revision 1.31 by root, Sun Jul 10 01:03:06 2005 UTC