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

Comparing Linux-AIO/AIO.pm (file contents):
Revision 1.2 by root, Tue Aug 14 18:06:37 2001 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		9	# This module has been mostly superseded by IO::AIO.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This module has been mostly superseded by IO::AIO, which is API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
		16	This module implements asynchronous I/O using the means available to Linux
		17	- clone. It does not hook into the POSIX aio_* functions because Linux
		18	does not yet support these in the kernel (even as of 2.6.12, only O_DIRECT
		19	files are supported) and even if, it would only allow aio_read and write,
		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.
		50
11	=over 4	51	=over 4
12		52
13	=cut	53	=cut
14		54
15	package Linux::AIO;	55	package Linux::AIO;
16		56
17	use base 'Exporter';	57	use base 'Exporter';
18		58
19	BEGIN {	59	BEGIN {
20	$VERSION = 0.001;	60	$VERSION = 1.9;
21		61
22	@EXPORT = qw(aio_read aio_write);	62	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink
		63	aio_fsync aio_fdatasync aio_readahead);
23	@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);
24		65
25	require XSLoader;	66	require XSLoader;
26	XSLoader::load Linux::AIO, $VERSION;	67	XSLoader::load Linux::AIO, $VERSION;
27	}	68	}
28		69
29	=item Linux::AIO::min_parallel($nthreads)	70	=item Linux::AIO::min_parallel $nthreads
30		71
31	Set the minimum number of AIO threads to $nthreads.	72	Set the minimum number of AIO threads to C<$nthreads>. The default is
		73	C<1>, which means a single asynchronous operation can be done at one time
		74	(the number of outstanding operations, however, is unlimited).
32		75
33	=cut	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).
34		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.
		93
		94	=item $fileno = Linux::AIO::poll_fileno
		95
		96	Return the I<request result pipe filehandle>. This filehandle must be
		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.
		102
		103	=item Linux::AIO::poll_cb
		104
		105	Process all outstanding events on the result pipe. You have to call this
		106	regularly. Returns the number of events processed. Returns immediately
		107	when no events are outstanding.
		108
		109	You can use Event to multiplex, e.g.:
		110
		111	Event->io (fd => Linux::AIO::poll_fileno,
		112	poll => 'r', async => 1,
		113	cb => \&Linux::AIO::poll_cb);
		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.
		122
		123	=item Linux::AIO::nreqs
		124
		125	Returns the number of requests currently outstanding.
		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
		132	=item aio_open $pathname, $flags, $mode, $callback
		133
		134	Asynchronously open or create a file and call the callback with the
		135	filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this
		136	might change in the future).
		137
		138	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
		139	for an explanation.
		140
		141	The C<$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
		156	=item aio_close $fh, $callback
		157
		158	Asynchronously close a file and call the callback with the result code.
		159
35	=item aio_read($fh,$offset,$length, $data,$dataoffset,$callback)	160	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
		161
36	aio_write($fh,$offset,$length, $data,$dataoffset,$callback)	162	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
37		163
38	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>
39	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
40	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).
41		168
42	=item $fileno = Linux::AIO::poll_fileno	169	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at
		170	offset C<0> within the scalar:
43		171
44	Return the request result pipe filehandle. This filehandle must be polled	172	aio_read $fh, 7, 15, $buffer, 0, sub {
45	for reading. If the pipe becomes readable you have to call C<poll_cb>.	173	$_[0] >= 0 or die "read error: $!";
		174	print "read <$buffer>\n";
		175	};
46		176
47	=item Linux::AIO::poll_cb	177	=item aio_readahead $fh,$offset,$length, $callback
48		178
49	Process all outstanding events on the result pipe. You have to call this	179	Asynchronously reads the specified byte range into the page cache, using
50	regularly. Returns the number of events processed.	180	the C<readahead> syscall.
51		181
52	=item Linux::AIO::nreqs	182	readahead() populates the page cache with data from a file so that
		183	subsequent reads from that file will not block on disk I/O. The C<$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.
53		190
54	Returns the number of requests currently outstanding.	191	=item aio_stat $fh_or_path, $callback
		192
		193	=item aio_lstat $fh, $callback
		194
		195	Works like perl's C<stat> or C<lstat> in void context. The callback will
		196	be called after the stat and the results will be available using C<stat _>
		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.
		201
		202	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
		203	error when stat'ing a large file, the results will be silently truncated
		204	unless perl itself is compiled with large file support.
		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.
55		227
56	=cut	228	=cut
		229
		230	min_parallel 1;
57		231
58	END {	232	END {
59	max_parallel 0;	233	max_parallel 0;
60	}	234	}
61		235
…		…
63		237
64	=back	238	=back
65		239
66	=head1 BUGS	240	=head1 BUGS
67		241
68	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.
69		244
70	This module does not use the aio_* posix functions because a) linux does	245	- aio_open gives a fd, but all other functions expect a perl filehandle.
71	not have aio, b) the existing aio_* functions use pthreads, which are too
72	buggy for my usage.
73		246
74	=head1 SEE ALSO	247	=head1 SEE ALSO
75		248
76	L<Coro>.	249	L<Coro>, L<IO::AIO>.
77		250
78	=head1 AUTHOR	251	=head1 AUTHOR
79		252
80	Marc Lehmann <pcg@goof.com>	253	Marc Lehmann <schmorp@schmorp.de>
81	http://www.goof.com/pcg/marc/	254	http://home.schmorp.de/
82		255
83	=cut	256	=cut
84		257

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Comparing Linux-AIO/AIO.pm (file contents): Revision 1.2 by root, Tue Aug 14 18:06:37 2001 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 1.2 by root, Tue Aug 14 18:06:37 2001 UTC vs.
Revision 1.37 by root, Wed Feb 1 23:47:26 2006 UTC