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

Comparing Linux-AIO/AIO.pm (file contents):
Revision 1.12 by root, Sat May 18 21:48:36 2002 UTC vs.
Revision 1.35 by root, Tue Jul 12 10:51:09 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.
		40
		41	The filenames you pass to these routines I<must> be absolute. The reason
		42	is that at the time the request is being executed, the current working
		43	directory could have changed. Alternatively, you can make sure that you
		44	never change the current working directory.
16		45
17	=over 4	46	=over 4
18		47
19	=cut	48	=cut
20		49
21	package Linux::AIO;	50	package Linux::AIO;
22		51
23	use base 'Exporter';	52	use base 'Exporter';
24		53
25	BEGIN {	54	BEGIN {
26	$VERSION = 0.111;	55	$VERSION = 1.72;
27		56
28	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat);	57	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink
		58	aio_fsync aio_fdatasync aio_readahead);
29	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs);	59	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs);
30		60
31	require XSLoader;	61	require XSLoader;
32	XSLoader::load Linux::AIO, $VERSION;	62	XSLoader::load Linux::AIO, $VERSION;
33	}	63	}
34		64
35	=item Linux::AIO::min_parallel($nthreads)	65	=item Linux::AIO::min_parallel $nthreads
36		66
37	Set the minimum number of AIO threads to $nthreads. You I<have> to call	67	Set the minimum number of AIO threads to C<$nthreads>. The default is
38	this function with a positive number at leats once, otherwise no threads	68	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.	69	(the number of outstanding operations, however, is unlimited).
		70
		71	It is recommended to keep the number of threads low, as some linux
		72	kernel versions will scale negatively with the number of threads (higher
		73	parallelity => MUCH higher latency).
		74
		75	Under normal circumstances you don't need to call this function, as this
		76	module automatically starts a single async thread.
		77
		78	=item Linux::AIO::max_parallel $nthreads
		79
		80	Sets the maximum number of AIO threads to C<$nthreads>. If more than
		81	the specified number of threads are currently running, kill them. This
		82	function blocks until the limit is reached.
		83
		84	This module automatically runs C<max_parallel 0> at program end, to ensure
		85	that all threads are killed and that there are no outstanding requests.
		86
		87	Under normal circumstances you don't need to call this function.
40		88
41	=item $fileno = Linux::AIO::poll_fileno	89	=item $fileno = Linux::AIO::poll_fileno
42		90
43	Return the request result pipe filehandle. This filehandle must be polled	91	Return the I<request result pipe filehandle>. This filehandle must be
44	for reading. If the pipe becomes readable you have to call C<poll_cb>.	92	polled for reading by some mechanism outside this module (e.g. Event
		93	or select, see below). If the pipe becomes readable you have to call
		94	C<poll_cb> to check the results.
		95
		96	See C<poll_cb> for an example.
45		97
46	=item Linux::AIO::poll_cb	98	=item Linux::AIO::poll_cb
47		99
48	Process all outstanding events on the result pipe. You have to call this	100	Process all outstanding events on the result pipe. You have to call this
49	regularly. Returns the number of events processed.	101	regularly. Returns the number of events processed. Returns immediately
		102	when no events are outstanding.
50		103
51	You can use Event to multiplex, e.g.:	104	You can use Event to multiplex, e.g.:
52		105
53	Event->io(fd => Linux::AIO::poll_fileno,	106	Event->io (fd => Linux::AIO::poll_fileno,
54	poll => 'r', async => 1,	107	poll => 'r', async => 1,
55	cb => \&Linux::AIO::poll_cb );	108	cb => \&Linux::AIO::poll_cb);
56		109
		110	=item Linux::AIO::poll_wait
		111
		112	Wait till the result filehandle becomes ready for reading (simply does a
		113	select on the filehandle. This is useful if you want to synchronously wait
		114	for some requests to finish).
		115
		116	See C<nreqs> for an example.
57		117
58	=item Linux::AIO::nreqs	118	=item Linux::AIO::nreqs
59		119
60	Returns the number of requests currently outstanding.	120	Returns the number of requests currently outstanding.
61		121
		122	Example: wait till there are no outstanding requests anymore:
		123
		124	Linux::AIO::poll_wait, Linux::AIO::poll_cb
		125	while Linux::AIO::nreqs;
		126
62	=item aio_open($pathname, $flags, $mode, $callback)	127	=item aio_open $pathname, $flags, $mode, $callback
63		128
64	Asynchronously open or create a file and call the callback with the	129	Asynchronously open or create a file and call the callback with the
65	filedescriptor.	130	filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this
		131	might change in the future).
66		132
		133	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
		134	for an explanation.
		135
		136	The C<$mode> argument is a bitmask. See the C<Fcntl> module for a
		137	list. They are the same as used in C<sysopen>.
		138
		139	Example:
		140
		141	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		142	if ($_[0] >= 0) {
		143	open my $fh, "<&=$_[0]";
		144	print "open successful, fh is $fh\n";
		145	...
		146	} else {
		147	die "open failed: $!\n";
		148	}
		149	};
		150
67	=item aio_close($fh, $callback)	151	=item aio_close $fh, $callback
68		152
69	Asynchronously close a file and call the callback with the result code.	153	Asynchronously close a file and call the callback with the result code.
70		154
71	=item aio_read($fh,$offset,$length, $data,$dataoffset,$callback)	155	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
72		156
73	=item aio_write($fh,$offset,$length, $data,$dataoffset,$callback)	157	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
74		158
75	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	159	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
76	into the scalar given by C<data> and offset C<dataoffset> and calls the	160	into the scalar given by C<data> and offset C<dataoffset> and calls the
77	callback without the actual number of bytes read (or undef on error).	161	callback without the actual number of bytes read (or -1 on error, just
		162	like the syscall).
78		163
		164	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at
		165	offset C<0> within the scalar:
		166
		167	aio_read $fh, 7, 15, $buffer, 0, sub {
		168	$_[0] >= 0 or die "read error: $!";
		169	print "read <$buffer>\n";
		170	};
		171
		172	=item aio_readahead $fh,$offset,$length, $callback
		173
		174	Asynchronously reads the specified byte range into the page cache, using
		175	the C<readahead> syscall.
		176
		177	readahead() populates the page cache with data from a file so that
		178	subsequent reads from that file will not block on disk I/O. The C<$offset>
		179	argument specifies the starting point from which data is to be read and
		180	C<$length> specifies the number of bytes to be read. I/O is performed in
		181	whole pages, so that offset is effectively rounded down to a page boundary
		182	and bytes are read up to the next page boundary greater than or equal to
		183	(off-set+length). aio_readahead() does not read beyond the end of the
		184	file. The current file offset of the file is left unchanged.
		185
79	=item aio_stat($fh_or_path,$callback)	186	=item aio_stat $fh_or_path, $callback
80		187
81	=item aio_lstat($fh,$callback)	188	=item aio_lstat $fh, $callback
82		189
83	Works like perl's C<stat> or C<lstat> in void context, i.e. the callback	190	Works like perl's C<stat> or C<lstat> in void context. The callback will
84	will be called after the stat and the results will be available using	191	be called after the stat and the results will be available using C<stat _>
85	C<stat _> or C<-s _> etc...	192	or C<-s _> etc...
		193
		194	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
		195	for an explanation.
86		196
87	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	197	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
88	error when stat'ing a large file, the results will be silently truncated	198	error when stat'ing a large file, the results will be silently truncated
89	unless perl itself is compiled with large file support.	199	unless perl itself is compiled with large file support.
90		200
		201	Example: Print the length of F</etc/passwd>:
		202
		203	aio_stat "/etc/passwd", sub {
		204	$_[0] and die "stat failed: $!";
		205	print "size is ", -s _, "\n";
		206	};
		207
		208	=item aio_unlink $pathname, $callback
		209
		210	Asynchronously unlink (delete) a file and call the callback with the
		211	result code.
		212
		213	=item aio_fsync $fh, $callback
		214
		215	Asynchronously call fsync on the given filehandle and call the callback
		216	with the fsync result code.
		217
		218	=item aio_fdatasync $fh, $callback
		219
		220	Asynchronously call fdatasync on the given filehandle and call the
		221	callback with the fdatasync result code.
		222
91	=cut	223	=cut
		224
		225	min_parallel 1;
92		226
93	END {	227	END {
94	max_parallel 0;	228	max_parallel 0;
95	}	229	}
96		230
…		…
98		232
99	=back	233	=back
100		234
101	=head1 BUGS	235	=head1 BUGS
102		236
103	This module has not yet been extensively tested. Watch out!	237	This module has been extensively tested in a large and very busy webserver
		238	for many years now.
104		239
105	- perl-threads/fork interaction poorly tested.
106	- aio_open gives a fd, but all other functions expect a filehandle.	240	- aio_open gives a fd, but all other functions expect a perl filehandle.
107		241
108	=head1 SEE ALSO	242	=head1 SEE ALSO
109		243
110	L<Coro>.	244	L<Coro>, L<IO::AIO>.
111		245
112	=head1 AUTHOR	246	=head1 AUTHOR
113		247
114	Marc Lehmann <pcg@goof.com>	248	Marc Lehmann <schmorp@schmorp.de>
115	http://www.goof.com/pcg/marc/	249	http://home.schmorp.de/
116		250
117	=cut	251	=cut
118		252

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Comparing Linux-AIO/AIO.pm (file contents): Revision 1.12 by root, Sat May 18 21:48:36 2002 UTC vs. Revision 1.35 by root, Tue Jul 12 10:51:09 2005 UTC

Diff Legend

Comparing Linux-AIO/AIO.pm (file contents):
Revision 1.12 by root, Sat May 18 21:48:36 2002 UTC vs.
Revision 1.35 by root, Tue Jul 12 10:51:09 2005 UTC