Using unsigned library work in the JDK
Joe Darcy
joe.darcy at oracle.com
Tue Feb 7 05:33:55 UTC 2012
Thanks Sherman; given the at most marginal performance cost, I'll push
the changes in the next day or two.
-Joe
On 02/06/2012 05:02 PM, Xueming Shen wrote:
> Joe,
>
> I did some non-scientific measure of the performance. test1() is to
> measure the change
> in a real "listing" operation on a ZipInputStream and test2() is a
> pure access on the byte[]
> directly. I don't see any significant difference on performance in
> both -client and -server
> vm. I would assume the change has no performance impact to the real
> zip access.
>
> In -client vm
> test1: 108 vs 109
> test2: 280 : 283
>
> Simple test case attached (the input is a big enough jar file, such as
> the rt.jar)
>
> -Sherman
>
> --------------------------------------------
>
> public static void main(String[] args) throws IOException {
>
> byte[] data = java.nio.file.Files.readAllBytes(new
> File(args[0]).toPath());
> ByteArrayInputStream bais = new ByteArrayInputStream(data);
>
> //warm up
> test1(bais, 100);
> System.out.printf("t=%d%n", test1(bais, 500));
>
> test2(data, 100);
> System.out.printf("t=%d%n", test2(data, 100));
> }
>
> static long test1(ByteArrayInputStream bais, int n) throws
> IOException {
> long t = 0;
> for (int i = 0; i < n; i++) {
> bais.reset();
>
> ZipInputStream zis = new ZipInputStream(bais);
> ZipEntry e;
> long t0 = System.currentTimeMillis();
> while ((e = zis.getNextEntry()) != null) {
> zis.closeEntry();
> //System.out.println(new String(e.getName()));
> }
> long t1 = System.currentTimeMillis();
> t += t1 - t0;
> }
> return t /= n;
> }
>
>
> static long test2(byte data[], int n) throws IOException {
> int j = 10000;
> long t = 0;
> if (j >= data.length -1)
> j = data.length -2;
> for (int m = 0; m < n; m++) {
> long t0 = System.nanoTime();
> int sum = 0;
> for (int i = 0; i < j; i++) {
> sum += get16(data, i);
> }
> long t1 = System.nanoTime();
> t += t1 - t0;
> }
> return t / n / 100;
> }
>
> private static final int get16(byte b[], int off) {
> return (b[off] & 0xff) | ((b[off+1] & 0xff) << 8);
> //return Byte.toUnsignedInt(b[off]) |
> (Byte.toUnsignedInt(b[off+1]) << 8);
>
> }
>
>
> On 1/26/2012 5:33 PM, Joe Darcy wrote:
>> Sherman, thanks for offering to investigate the performance impact,
>> if any, of this change.
>>
>> -Joe
>>
>> PS All the jar/zip regression tests pass with this change.
>>
>> On 01/26/2012 09:52 AM, Xueming Shen wrote:
>>> Joe,
>>>
>>> The changes look fine. However I have the same performance concern in
>>> cases that the vm fails to inline the toUnsignedInt(), especially
>>> for those
>>> "simple" one line utility methods, such as the get16(), CH(), SH(), my
>>> guess is that it might have a performance impact. It might not be a big
>>> deal for operation like creating or extracting a jar/zip file but
>>> probably will
>>> slow down the loc/cen table reading only operation such as list a
>>> jar/zip
>>> file. I will try to get some performance data to see if the impact is
>>> "significant" enough to be a real concern.
>>>
>>> -Sherman
>>>
>>> On 01/25/2012 08:37 PM, Joe Darcy wrote:
>>>> Hello,
>>>>
>>>> As a follow-up to the recent push of unsigned library support in
>>>> the JDK [1], I grepped -i for "0xff" in the JDK code base to look
>>>> for candidate locations to use the new methods. I choose to first
>>>> tackle some jar/zip code.
>>>>
>>>> Sherman, can you review the changes below?
>>>>
>>>> diff -r 303b67074666
>>>> src/share/classes/java/util/jar/JarOutputStream.java
>>>> --- a/src/share/classes/java/util/jar/JarOutputStream.java Tue
>>>> Jan 24 15:13:27 2012 -0500
>>>> +++ b/src/share/classes/java/util/jar/JarOutputStream.java Wed
>>>> Jan 25 20:31:05 2012 -0800
>>>> @@ -1,5 +1,5 @@
>>>> /*
>>>> - * Copyright (c) 1997, 2006, Oracle and/or its affiliates. All
>>>> rights reserved.
>>>> + * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All
>>>> rights reserved.
>>>> * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
>>>> *
>>>> * This code is free software; you can redistribute it and/or
>>>> modify it
>>>> @@ -135,7 +135,7 @@
>>>> * The bytes are assumed to be in Intel (little-endian) byte
>>>> order.
>>>> */
>>>> private static int get16(byte[] b, int off) {
>>>> - return (b[off] & 0xff) | ((b[off+1] & 0xff) << 8);
>>>> + return Byte.toUnsignedInt(b[off]) | (
>>>> Byte.toUnsignedInt(b[off+1]) << 8);
>>>> }
>>>>
>>>> /*
>>>> diff -r 303b67074666 src/share/classes/java/util/jar/Manifest.java
>>>> --- a/src/share/classes/java/util/jar/Manifest.java Tue Jan 24
>>>> 15:13:27 2012 -0500
>>>> +++ b/src/share/classes/java/util/jar/Manifest.java Wed Jan 25
>>>> 20:31:05 2012 -0800
>>>> @@ -1,5 +1,5 @@
>>>> /*
>>>> - * Copyright (c) 1997, 2006, Oracle and/or its affiliates. All
>>>> rights reserved.
>>>> + * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All
>>>> rights reserved.
>>>> * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
>>>> *
>>>> * This code is free software; you can redistribute it and/or
>>>> modify it
>>>> @@ -339,7 +339,7 @@
>>>> return -1;
>>>> }
>>>> }
>>>> - return buf[pos++] & 0xff;
>>>> + return Byte.toUnsignedInt(buf[pos++]);
>>>> }
>>>>
>>>> public int read(byte[] b, int off, int len) throws
>>>> IOException {
>>>> diff -r 303b67074666
>>>> src/share/classes/java/util/zip/InflaterInputStream.java
>>>> --- a/src/share/classes/java/util/zip/InflaterInputStream.java
>>>> Tue Jan 24 15:13:27 2012 -0500
>>>> +++ b/src/share/classes/java/util/zip/InflaterInputStream.java
>>>> Wed Jan 25 20:31:05 2012 -0800
>>>> @@ -1,5 +1,5 @@
>>>> /*
>>>> - * Copyright (c) 1996, 2006, Oracle and/or its affiliates. All
>>>> rights reserved.
>>>> + * Copyright (c) 1996, 2012, Oracle and/or its affiliates. All
>>>> rights reserved.
>>>> * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
>>>> *
>>>> * This code is free software; you can redistribute it and/or
>>>> modify it
>>>> @@ -119,7 +119,7 @@
>>>> */
>>>> public int read() throws IOException {
>>>> ensureOpen();
>>>> - return read(singleByteBuf, 0, 1) == -1 ? -1 :
>>>> singleByteBuf[0] & 0xff;
>>>> + return read(singleByteBuf, 0, 1) == -1 ? -1 :
>>>> Byte.toUnsignedInt(singleByteBuf[0]);
>>>> }
>>>>
>>>> /**
>>>> diff -r 303b67074666
>>>> src/share/classes/java/util/zip/ZipInputStream.java
>>>> --- a/src/share/classes/java/util/zip/ZipInputStream.java Tue
>>>> Jan 24 15:13:27 2012 -0500
>>>> +++ b/src/share/classes/java/util/zip/ZipInputStream.java Wed
>>>> Jan 25 20:31:05 2012 -0800
>>>> @@ -1,5 +1,5 @@
>>>> /*
>>>> - * Copyright (c) 1996, 2009, Oracle and/or its affiliates. All
>>>> rights reserved.
>>>> + * Copyright (c) 1996, 2012, Oracle and/or its affiliates. All
>>>> rights reserved.
>>>> * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
>>>> *
>>>> * This code is free software; you can redistribute it and/or
>>>> modify it
>>>> @@ -435,7 +435,7 @@
>>>> * The bytes are assumed to be in Intel (little-endian) byte
>>>> order.
>>>> */
>>>> private static final int get16(byte b[], int off) {
>>>> - return (b[off] & 0xff) | ((b[off+1] & 0xff) << 8);
>>>> + return Byte.toUnsignedInt(b[off]) |
>>>> (Byte.toUnsignedInt(b[off+1]) << 8);
>>>> }
>>>>
>>>> /*
>>>> diff -r 303b67074666
>>>> src/share/demo/nio/zipfs/src/com/sun/nio/zipfs/ZipConstants.java
>>>> ---
>>>> a/src/share/demo/nio/zipfs/src/com/sun/nio/zipfs/ZipConstants.java
>>>> Tue Jan 24 15:13:27 2012 -0500
>>>> +++
>>>> b/src/share/demo/nio/zipfs/src/com/sun/nio/zipfs/ZipConstants.java
>>>> Wed Jan 25 20:31:05 2012 -0800
>>>> @@ -185,11 +185,11 @@
>>>> */
>>>> ///////////////////////////////////////////////////////
>>>> static final int CH(byte[] b, int n) {
>>>> - return b[n] & 0xff;
>>>> + return Byte.toUnsignedInt(b[n]);
>>>> }
>>>>
>>>> static final int SH(byte[] b, int n) {
>>>> - return (b[n] & 0xff) | ((b[n + 1] & 0xff) << 8);
>>>> + return Byte.toUnsignedInt(b[n]) | (Byte.toUnsignedInt(b[n
>>>> + 1]) << 8);
>>>> }
>>>>
>>>> static final long LG(byte[] b, int n) {
>>>>
>>>> If the changes look good, I'll file a bug for them, etc.
>>>>
>>>> In case other people want to look over candidates sites in
>>>> different areas, I've included the list of JDK files using "0xff"
>>>> below.
>>>>
>>>> Thanks,
>>>>
>>>> -Joe
>>>>
>>>> [1] 4504839: Java libraries should provide support for unsigned
>>>> integer arithmetic
>>>> http://mail.openjdk.java.net/pipermail/core-libs-dev/2012-January/008926.html
>>>>
>>>>
>>>> .
>>
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