[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 1.37 by root, Wed Feb 1 23:47:26 2006 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use Linux::AIO;	7	use Linux::AIO;
8		8
		9	# This module has been mostly superseded by IO::AIO.
		10
9	=head1 DESCRIPTION	11	=head1 DESCRIPTION
10		12
		13	I<This module has been mostly superseded by IO::AIO, which is API
		14	compatible.>
		15
11	This module implements asynchroneous i/o using the means available to	16	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	17	- 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	18	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	19	files are supported) and even if, it would only allow aio_read and write,
15	completion.	20	not open, stat and so on.
		21
		22	Instead, in this module a number of (non-posix) threads are started that
		23	execute your read/writes and signal their completion. You don't need
		24	thread support in your libc or perl, and the threads created by this
		25	module will not be visible to the pthreads library.
		26
		27	NOTICE: the threads created by this module will automatically be killed
		28	when the thread calling min_parallel exits. Make sure you only ever call
		29	min_parallel from the same thread that loaded this module.
		30
		31	Although the module will work with in the presence of other threads, it is
		32	not reentrant, so use appropriate locking yourself.
		33
		34	=head2 API NOTES
		35
		36	All the C<aio_*> calls are more or less thin wrappers around the syscall
		37	with the same name (sans C<aio_>). The arguments are similar or identical,
		38	and they all accept an additional C<$callback> argument which must be
		39	a code reference. This code reference will get called with the syscall
		40	return code (e.g. most syscalls return C<-1> on error, unlike perl, which
		41	usually delivers "false") as it's sole argument when the given syscall has
		42	been executed asynchronously.
		43
		44	All functions that expect a filehandle will also accept a file descriptor.
		45
		46	The filenames you pass to these routines I<must> be absolute. The reason
		47	is that at the time the request is being executed, the current working
		48	directory could have changed. Alternatively, you can make sure that you
		49	never change the current working directory.
16		50
17	=over 4	51	=over 4
18		52
19	=cut	53	=cut
20		54
21	package Linux::AIO;	55	package Linux::AIO;
22		56
23	use base 'Exporter';	57	use base 'Exporter';
24		58
25	BEGIN {	59	BEGIN {
26	$VERSION = 0.111;	60	$VERSION = 1.9;
27		61
28	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat);	62	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink
		63	aio_fsync aio_fdatasync aio_readahead);
29	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs);	64	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs);
30		65
31	require XSLoader;	66	require XSLoader;
32	XSLoader::load Linux::AIO, $VERSION;	67	XSLoader::load Linux::AIO, $VERSION;
33	}	68	}
34		69
35	=item Linux::AIO::min_parallel($nthreads)	70	=item Linux::AIO::min_parallel $nthreads
36		71
37	Set the minimum number of AIO threads to $nthreads. You I<have> to call	72	Set the minimum number of AIO threads to C<$nthreads>. The default is
38	this function with a positive number at leats once, otherwise no threads	73	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.	74	(the number of outstanding operations, however, is unlimited).
		75
		76	It is recommended to keep the number of threads low, as some linux
		77	kernel versions will scale negatively with the number of threads (higher
		78	parallelity => MUCH higher latency).
		79
		80	Under normal circumstances you don't need to call this function, as this
		81	module automatically starts a single async thread.
		82
		83	=item Linux::AIO::max_parallel $nthreads
		84
		85	Sets the maximum number of AIO threads to C<$nthreads>. If more than
		86	the specified number of threads are currently running, kill them. This
		87	function blocks until the limit is reached.
		88
		89	This module automatically runs C<max_parallel 0> at program end, to ensure
		90	that all threads are killed and that there are no outstanding requests.
		91
		92	Under normal circumstances you don't need to call this function.
40		93
41	=item $fileno = Linux::AIO::poll_fileno	94	=item $fileno = Linux::AIO::poll_fileno
42		95
43	Return the request result pipe filehandle. This filehandle must be polled	96	Return the I<request result pipe filehandle>. This filehandle must be
44	for reading. If the pipe becomes readable you have to call C<poll_cb>.	97	polled for reading by some mechanism outside this module (e.g. Event
		98	or select, see below). If the pipe becomes readable you have to call
		99	C<poll_cb> to check the results.
		100
		101	See C<poll_cb> for an example.
45		102
46	=item Linux::AIO::poll_cb	103	=item Linux::AIO::poll_cb
47		104
48	Process all outstanding events on the result pipe. You have to call this	105	Process all outstanding events on the result pipe. You have to call this
49	regularly. Returns the number of events processed.	106	regularly. Returns the number of events processed. Returns immediately
		107	when no events are outstanding.
50		108
51	You can use Event to multiplex, e.g.:	109	You can use Event to multiplex, e.g.:
52		110
53	Event->io(fd => Linux::AIO::poll_fileno,	111	Event->io (fd => Linux::AIO::poll_fileno,
54	poll => 'r', async => 1,	112	poll => 'r', async => 1,
55	cb => \&Linux::AIO::poll_cb );	113	cb => \&Linux::AIO::poll_cb);
56		114
		115	=item Linux::AIO::poll_wait
		116
		117	Wait till the result filehandle becomes ready for reading (simply does a
		118	select on the filehandle. This is useful if you want to synchronously wait
		119	for some requests to finish).
		120
		121	See C<nreqs> for an example.
57		122
58	=item Linux::AIO::nreqs	123	=item Linux::AIO::nreqs
59		124
60	Returns the number of requests currently outstanding.	125	Returns the number of requests currently outstanding.
61		126
		127	Example: wait till there are no outstanding requests anymore:
		128
		129	Linux::AIO::poll_wait, Linux::AIO::poll_cb
		130	while Linux::AIO::nreqs;
		131
62	=item aio_open($pathname, $flags, $mode, $callback)	132	=item aio_open $pathname, $flags, $mode, $callback
63		133
64	Asynchronously open or create a file and call the callback with the	134	Asynchronously open or create a file and call the callback with the
65	filedescriptor.	135	filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this
		136	might change in the future).
66		137
		138	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
		139	for an explanation.
		140
		141	The C<$mode> argument is a bitmask. See the C<Fcntl> module for a
		142	list. They are the same as used in C<sysopen>.
		143
		144	Example:
		145
		146	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		147	if ($_[0] >= 0) {
		148	open my $fh, "<&=$_[0]";
		149	print "open successful, fh is $fh\n";
		150	...
		151	} else {
		152	die "open failed: $!\n";
		153	}
		154	};
		155
67	=item aio_close($fh, $callback)	156	=item aio_close $fh, $callback
68		157
69	Asynchronously close a file and call the callback with the result code.	158	Asynchronously close a file and call the callback with the result code.
70		159
71	=item aio_read($fh,$offset,$length, $data,$dataoffset,$callback)	160	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
72		161
73	=item aio_write($fh,$offset,$length, $data,$dataoffset,$callback)	162	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
74		163
75	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	164	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
76	into the scalar given by C<data> and offset C<dataoffset> and calls the	165	into the scalar given by C<data> and offset C<dataoffset> and calls the
77	callback without the actual number of bytes read (or undef on error).	166	callback without the actual number of bytes read (or -1 on error, just
		167	like the syscall).
78		168
		169	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at
		170	offset C<0> within the scalar:
		171
		172	aio_read $fh, 7, 15, $buffer, 0, sub {
		173	$_[0] >= 0 or die "read error: $!";
		174	print "read <$buffer>\n";
		175	};
		176
		177	=item aio_readahead $fh,$offset,$length, $callback
		178
		179	Asynchronously reads the specified byte range into the page cache, using
		180	the C<readahead> syscall.
		181
		182	readahead() populates the page cache with data from a file so that
		183	subsequent reads from that file will not block on disk I/O. The C<$offset>
		184	argument specifies the starting point from which data is to be read and
		185	C<$length> specifies the number of bytes to be read. I/O is performed in
		186	whole pages, so that offset is effectively rounded down to a page boundary
		187	and bytes are read up to the next page boundary greater than or equal to
		188	(off-set+length). aio_readahead() does not read beyond the end of the
		189	file. The current file offset of the file is left unchanged.
		190
79	=item aio_stat($fh_or_path,$callback)	191	=item aio_stat $fh_or_path, $callback
80		192
81	=item aio_lstat($fh,$callback)	193	=item aio_lstat $fh, $callback
82		194
83	Works like perl's C<stat> or C<lstat> in void context, i.e. the callback	195	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	196	be called after the stat and the results will be available using C<stat _>
85	C<stat _> or C<-s _> etc...	197	or C<-s _> etc...
		198
		199	The pathname passed to C<aio_stat> must be absolute. See API NOTES, above,
		200	for an explanation.
86		201
87	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	202	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	203	error when stat'ing a large file, the results will be silently truncated
89	unless perl itself is compiled with large file support.	204	unless perl itself is compiled with large file support.
90		205
		206	Example: Print the length of F</etc/passwd>:
		207
		208	aio_stat "/etc/passwd", sub {
		209	$_[0] and die "stat failed: $!";
		210	print "size is ", -s _, "\n";
		211	};
		212
		213	=item aio_unlink $pathname, $callback
		214
		215	Asynchronously unlink (delete) a file and call the callback with the
		216	result code.
		217
		218	=item aio_fsync $fh, $callback
		219
		220	Asynchronously call fsync on the given filehandle and call the callback
		221	with the fsync result code.
		222
		223	=item aio_fdatasync $fh, $callback
		224
		225	Asynchronously call fdatasync on the given filehandle and call the
		226	callback with the fdatasync result code.
		227
91	=cut	228	=cut
		229
		230	min_parallel 1;
92		231
93	END {	232	END {
94	max_parallel 0;	233	max_parallel 0;
95	}	234	}
96		235
…		…
98		237
99	=back	238	=back
100		239
101	=head1 BUGS	240	=head1 BUGS
102		241
103	This module has not yet been extensively tested. Watch out!	242	This module has been extensively tested in a large and very busy webserver
		243	for many years now.
104		244
105	- perl-threads/fork interaction poorly tested.
106	- aio_open gives a fd, but all other functions expect a filehandle.	245	- aio_open gives a fd, but all other functions expect a perl filehandle.
107		246
108	=head1 SEE ALSO	247	=head1 SEE ALSO
109		248
110	L<Coro>.	249	L<Coro>, L<IO::AIO>.
111		250
112	=head1 AUTHOR	251	=head1 AUTHOR
113		252
114	Marc Lehmann <pcg@goof.com>	253	Marc Lehmann <schmorp@schmorp.de>
115	http://www.goof.com/pcg/marc/	254	http://home.schmorp.de/
116		255
117	=cut	256	=cut
118		257

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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 1.37 by root, Wed Feb 1 23:47:26 2006 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 1.37 by root, Wed Feb 1 23:47:26 2006 UTC