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Optimize XxHash64.apply method #125

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Optimize XxHash64.apply method #125

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82 changes: 37 additions & 45 deletions webbeans-impl/src/main/java/org/apache/webbeans/hash/XxHash64.java
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Original file line number Diff line number Diff line change
Expand Up @@ -74,21 +74,10 @@ public static long apply(final ByteBuffer input)

do
{
v1 += input.getLong(off) * PRIME64_2;
v1 = Long.rotateLeft(v1, 31);
v1 *= PRIME64_1;

v2 += input.getLong(off + 8) * PRIME64_2;
v2 = Long.rotateLeft(v2, 31);
v2 *= PRIME64_1;

v3 += input.getLong(off + 16) * PRIME64_2;
v3 = Long.rotateLeft(v3, 31);
v3 *= PRIME64_1;

v4 += input.getLong(off + 24) * PRIME64_2;
v4 = Long.rotateLeft(v4, 31);
v4 *= PRIME64_1;
v1 = processChunk(input, off, v1);
v2 = processChunk(input, off + 8, v2);
v3 = processChunk(input, off + 16, v3);
v4 = processChunk(input, off + 24, v4);

off += 32;
remaining -= 32;
Expand All @@ -100,29 +89,10 @@ public static long apply(final ByteBuffer input)
+ Long.rotateLeft(v3, 12)
+ Long.rotateLeft(v4, 18);

v1 *= PRIME64_2;
v1 = Long.rotateLeft(v1, 31);
v1 *= PRIME64_1;
hash ^= v1;
hash = hash * PRIME64_1 + PRIME64_4;

v2 *= PRIME64_2;
v2 = Long.rotateLeft(v2, 31);
v2 *= PRIME64_1;
hash ^= v2;
hash = hash * PRIME64_1 + PRIME64_4;

v3 *= PRIME64_2;
v3 = Long.rotateLeft(v3, 31);
v3 *= PRIME64_1;
hash ^= v3;
hash = hash * PRIME64_1 + PRIME64_4;

v4 *= PRIME64_2;
v4 = Long.rotateLeft(v4, 31);
v4 *= PRIME64_1;
hash ^= v4;
hash = hash * PRIME64_1 + PRIME64_4;
hash = finalizeHash(hash, v1);
hash = finalizeHash(hash, v2);
hash = finalizeHash(hash, v3);
hash = finalizeHash(hash, v4);
}
else
{
Expand All @@ -133,12 +103,7 @@ public static long apply(final ByteBuffer input)

while (remaining >= 8)
{
long k1 = input.getLong(off);
k1 *= PRIME64_2;
k1 = Long.rotateLeft(k1, 31);
k1 *= PRIME64_1;
hash ^= k1;
hash = Long.rotateLeft(hash, 27) * PRIME64_1 + PRIME64_4;
hash = processRemaining(input, off, hash, 8);
off += 8;
remaining -= 8;
}
Expand All @@ -162,6 +127,33 @@ public static long apply(final ByteBuffer input)
return finalize(hash);
}

private static long processChunk(ByteBuffer input, int offset, long value)
{
value += input.getLong(offset) * PRIME64_2;
value = Long.rotateLeft(value, 31);
value *= PRIME64_1;
return value;
}

private static long finalizeHash(long hash, long value)
{
value *= PRIME64_2;
value = Long.rotateLeft(value, 31);
value *= PRIME64_1;
hash ^= value;
return hash * PRIME64_1 + PRIME64_4;
}

private static long processRemaining(ByteBuffer input, int offset, long hash, int length)
{
long k1 = input.getLong(offset);
k1 *= PRIME64_2;
k1 = Long.rotateLeft(k1, 31);
k1 *= PRIME64_1;
hash ^= k1;
return Long.rotateLeft(hash, 27) * PRIME64_1 + PRIME64_4;
}

private static long finalize(long hash)
{
hash ^= hash >>> 33;
Expand All @@ -171,4 +163,4 @@ private static long finalize(long hash)
hash ^= hash >>> 32;
return hash;
}
}
}