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net.openhft.chronicle.algo.hashing.MurmurHash_3 Maven / Gradle / Ivy
/*
* Copyright 2014 Higher Frequency Trading http://www.higherfrequencytrading.com
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package net.openhft.chronicle.algo.hashing;
import net.openhft.chronicle.algo.bytes.ReadAccess;
import static java.lang.Long.reverseBytes;
import static java.nio.ByteOrder.LITTLE_ENDIAN;
import static net.openhft.chronicle.algo.hashing.LongHashFunction.NATIVE_LITTLE_ENDIAN;
/**
* Derived from https://github.com/google/guava/blob/fa95e381e665d8ee9639543b99ed38020c8de5ef
* /guava/src/com/google/common/hash/Murmur3_128HashFunction.java
*/
class MurmurHash_3 {
private static final MurmurHash_3 INSTANCE = new MurmurHash_3();
private static final MurmurHash_3 NATIVE_MURMUR = NATIVE_LITTLE_ENDIAN ?
MurmurHash_3.INSTANCE : BigEndian.INSTANCE;
private static final long C1 = 0x87c37b91114253d5L;
private static final long C2 = 0x4cf5ad432745937fL;
private MurmurHash_3() {}
private static long finalize(long length, long h1, long h2) {
h1 ^= length;
h2 ^= length;
h1 += h2;
h2 += h1;
h1 = fmix64(h1);
h2 = fmix64(h2);
h1 += h2;
return h1;
}
private static long fmix64(long k) {
k ^= k >>> 33;
k *= 0xff51afd7ed558ccdL;
k ^= k >>> 33;
k *= 0xc4ceb9fe1a85ec53L;
k ^= k >>> 33;
return k;
}
private static long mixK1(long k1) {
k1 *= C1;
k1 = Long.rotateLeft(k1, 31);
k1 *= C2;
return k1;
}
private static long mixK2(long k2) {
k2 *= C2;
k2 = Long.rotateLeft(k2, 33);
k2 *= C1;
return k2;
}
public static LongHashFunction asLongHashFunctionWithoutSeed() {
return AsLongHashFunction.INSTANCE;
}
public static LongHashFunction asLongHashFunctionWithSeed(long seed) {
return new AsLongHashFunctionSeeded(seed);
}
long fetch64(ReadAccess access, T in, long off) {
return access.readLong(in, off);
}
int fetch32(ReadAccess access, T in, long off) {
return access.readInt(in, off);
}
long toLittleEndian(long v) {
return v;
}
int toLittleEndian(int v) {
return v;
}
int toLittleEndianShort(int unsignedShort) {
return unsignedShort;
}
public long hash(long seed, T input, ReadAccess access, long offset, long length) {
long h1 = seed;
long h2 = seed;
long remaining = length;
while (remaining >= 16L) {
long k1 = fetch64(access, input, offset);
long k2 = fetch64(access, input, offset + 8L);
offset += 16L;
remaining -= 16L;
h1 ^= mixK1(k1);
h1 = Long.rotateLeft(h1, 27);
h1 += h2;
h1 = h1 * 5L + 0x52dce729L;
h2 ^= mixK2(k2);
h2 = Long.rotateLeft(h2, 31);
h2 += h1;
h2 = h2 * 5L + 0x38495ab5L;
}
if (remaining > 0L) {
long k1 = 0L;
long k2 = 0L;
switch ((int) remaining) {
case 15:
k2 ^= ((long) access.readUnsignedByte(input, offset + 14L)) << 48;//fall through
case 14:
k2 ^= ((long) access.readUnsignedByte(input, offset + 13L)) << 40;//fall through
case 13:
k2 ^= ((long) access.readUnsignedByte(input, offset + 12L)) << 32;//fall through
case 12:
k2 ^= ((long) access.readUnsignedByte(input, offset + 11L)) << 24;//fall through
case 11:
k2 ^= ((long) access.readUnsignedByte(input, offset + 10L)) << 16;//fall through
case 10:
k2 ^= ((long) access.readUnsignedByte(input, offset + 9L)) << 8; // fall through
case 9:
k2 ^= ((long) access.readUnsignedByte(input, offset + 8L)); // fall through
case 8:
k1 ^= fetch64(access, input, offset);
break;
case 7:
k1 ^= ((long) access.readUnsignedByte(input, offset + 6L)) << 48;// fall through
case 6:
k1 ^= ((long) access.readUnsignedByte(input, offset + 5L)) << 40;// fall through
case 5:
k1 ^= ((long) access.readUnsignedByte(input, offset + 4L)) << 32;// fall through
case 4:
k1 ^= Primitives.unsignedInt(fetch32(access, input, offset));
break;
case 3:
k1 ^= ((long) access.readUnsignedByte(input, offset + 2L)) << 16;// fall through
case 2:
k1 ^= ((long) access.readUnsignedByte(input, offset + 1L)) << 8; // fall through
case 1:
k1 ^= ((long) access.readUnsignedByte(input, offset));
case 0:
break;
default:
throw new AssertionError("Should never get here.");
}
h1 ^= mixK1(k1);
h2 ^= mixK2(k2);
}
// This version appears to be working slower
// if (remaining > 0L) {
// long k1 = 0L;
// long k2 = 0L;
// megaSwitch:
// {
// fetch0_7:
// {
// fetch8_11:
// {
// fetch0_3:
// {
// switch ((int) remaining) {
// case 15:
// k2 ^= ((long) access.readUnsignedByte(input, offset + 14L)) << 48;
// case 14:
// k2 ^= ((long) toLittleEndianShort(
// access.getUnsignedShort(input, offset + 12L))) << 32;
// break fetch8_11;
// case 13:
// k2 ^= ((long) access.readUnsignedByte(input, offset + 12L)) << 32;
// case 12:
// break fetch8_11;
// case 11:
// k2 ^= ((long) access.readUnsignedByte(input, offset + 10L)) << 16;
// case 10:
// k2 ^= (long) toLittleEndianShort(
// access.getUnsignedShort(input, offset + 8L));
// break fetch0_7;
// case 9:
// k2 ^= ((long) access.readUnsignedByte(input, offset + 8L));
// case 8:
// break fetch0_7;
// case 7:
// k1 ^= ((long) access.readUnsignedByte(input, offset + 6L)) << 48;
// case 6:
// k1 ^= ((long) toLittleEndianShort(
// access.getUnsignedShort(input, offset + 4L))) << 32;
// break fetch0_3;
// case 5:
// k1 ^= ((long) access.readUnsignedByte(input, offset + 4L)) << 32;
// case 4:
// break fetch0_3;
// case 3:
// k1 ^= ((long) access.readUnsignedByte(input, offset + 2L)) << 16;
// case 2:
// k1 ^= (long) toLittleEndianShort(
// access.getUnsignedShort(input, offset));
// break megaSwitch;
// case 1:
// k1 ^= ((long) access.readUnsignedByte(input, offset));
// break megaSwitch;
// default:
// throw new AssertionError();
// }
// } // fetch0_3
// k1 ^= unsignedInt(fetch32(access, input, offset));
// break megaSwitch;
// } // fetch8_11
// k2 ^= unsignedInt(fetch32(access, input, offset + 8L));
// } // fetch0_7
// k1 ^= fetch64(access, input, offset);
// } // megaSwitch
//
// h1 ^= mixK1(k1);
// h2 ^= mixK2(k2);
// }
return finalize(length, h1, h2);
}
private static class BigEndian extends MurmurHash_3 {
private static final BigEndian INSTANCE = new BigEndian();
private BigEndian() {}
@Override
long fetch64(ReadAccess access, T in, long off) {
return reverseBytes(super.fetch64(access, in, off));
}
@Override
int fetch32(ReadAccess access, T in, long off) {
return Integer.reverseBytes(super.fetch32(access, in, off));
}
@Override
long toLittleEndian(long v) {
return reverseBytes(v);
}
@Override
int toLittleEndian(int v) {
return Integer.reverseBytes(v);
}
@Override
int toLittleEndianShort(int unsignedShort) {
return ((unsignedShort & 0xFF) << 8) | (unsignedShort >> 8);
}
}
private static class AsLongHashFunction extends LongHashFunction {
public static final AsLongHashFunction INSTANCE = new AsLongHashFunction();
private static final long serialVersionUID = 0L;
private Object readResolve() {
return INSTANCE;
}
long seed() {
return 0L;
}
long hashNativeLong(long nativeLong, long len) {
long h1 = mixK1(nativeLong);
long h2 = 0L;
return MurmurHash_3.finalize(len, h1, h2);
}
@Override
public long hashLong(long input) {
return hashNativeLong(NATIVE_MURMUR.toLittleEndian(input), 8L);
}
@Override
public long hashInt(int input) {
return hashNativeLong(Primitives.unsignedInt(NATIVE_MURMUR.toLittleEndian(input)), 4L);
}
@Override
public long hashShort(short input) {
return hashNativeLong(
(long) NATIVE_MURMUR.toLittleEndianShort(Primitives.unsignedShort(input)), 2L);
}
@Override
public long hashChar(char input) {
return hashNativeLong((long) NATIVE_MURMUR.toLittleEndianShort((int) input), 2L);
}
@Override
public long hashByte(byte input) {
return hashNativeLong((long) Primitives.unsignedByte((int) input), 1L);
}
@Override
public long hashVoid() {
return 0L;
}
@Override
public long hash(T input, ReadAccess access, long off, long len) {
long seed = seed();
if (access.byteOrder(input) == LITTLE_ENDIAN) {
return MurmurHash_3.INSTANCE.hash(seed, input, access, off, len);
} else {
return BigEndian.INSTANCE.hash(seed, input, access, off, len);
}
}
}
private static class AsLongHashFunctionSeeded extends AsLongHashFunction {
private static final long serialVersionUID = 0L;
private final long seed;
private transient long voidHash;
private AsLongHashFunctionSeeded(long seed) {
this.seed = seed;
voidHash = MurmurHash_3.finalize(0L, seed, seed);
}
@Override
long seed() {
return seed;
}
@Override
long hashNativeLong(long nativeLong, long len) {
long seed = this.seed;
long h1 = seed ^ mixK1(nativeLong);
long h2 = seed;
return MurmurHash_3.finalize(len, h1, h2);
}
@Override
public long hashVoid() {
return voidHash;
}
}
}
