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net.openhft.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.hashing;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import javax.annotation.ParametersAreNonnullByDefault;
import static java.nio.ByteOrder.LITTLE_ENDIAN;
import static net.openhft.hashing.Primitives.unsignedInt;
import static net.openhft.hashing.Primitives.unsignedShort;
/**
* Derived from https://github.com/google/guava/blob/fa95e381e665d8ee9639543b99ed38020c8de5ef
* /guava/src/com/google/common/hash/Murmur3_128HashFunction.java
*/
@ParametersAreNonnullByDefault
class MurmurHash_3 {
private static final long C1 = 0x87c37b91114253d5L;
private static final long C2 = 0x4cf5ad432745937fL;
private static long hash(long seed, @Nullable T input, Access access, long offset, long length, @Nullable long[] result) {
long h1 = seed;
long h2 = seed;
long remaining = length;
while (remaining >= 16L) {
long k1 = access.i64(input, offset);
long k2 = access.i64(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.u8(input, offset + 14L)) << 48;// fall through
case 14:
k2 ^= ((long) access.u8(input, offset + 13L)) << 40;// fall through
case 13:
k2 ^= ((long) access.u8(input, offset + 12L)) << 32;// fall through
case 12:
k2 ^= ((long) access.u8(input, offset + 11L)) << 24;// fall through
case 11:
k2 ^= ((long) access.u8(input, offset + 10L)) << 16;// fall through
case 10:
k2 ^= ((long) access.u8(input, offset + 9L)) << 8; // fall through
case 9:
k2 ^= ((long) access.u8(input, offset + 8L)); // fall through
case 8:
k1 ^= access.i64(input, offset);
break;
case 7:
k1 ^= ((long) access.u8(input, offset + 6L)) << 48; // fall through
case 6:
k1 ^= ((long) access.u8(input, offset + 5L)) << 40; // fall through
case 5:
k1 ^= ((long) access.u8(input, offset + 4L)) << 32; // fall through
case 4:
k1 ^= access.u32(input, offset);
break;
case 3:
k1 ^= ((long) access.u8(input, offset + 2L)) << 16; // fall through
case 2:
k1 ^= ((long) access.u8(input, offset + 1L)) << 8; // fall through
case 1:
k1 ^= ((long) access.u8(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.u8(input, offset + 14L)) << 48;
// case 14:
// k2 ^= ((long) Primitives.nativeToLittleEndian(
// access.u16(input, offset + 12L))) << 32;
// break fetch8_11;
// case 13:
// k2 ^= ((long) access.u8(input, offset + 12L)) << 32;
// case 12:
// break fetch8_11;
// case 11:
// k2 ^= ((long) access.u8(input, offset + 10L)) << 16;
// case 10:
// k2 ^= (long) Primitives.nativeToLittleEndian(
// access.u16(input, offset + 8L));
// break fetch0_7;
// case 9:
// k2 ^= ((long) access.u8(input, offset + 8L));
// case 8:
// break fetch0_7;
// case 7:
// k1 ^= ((long) access.u8(input, offset + 6L)) << 48;
// case 6:
// k1 ^= ((long) Primitives.nativeToLittleEndian(
// access.u16(input, offset + 4L))) << 32;
// break fetch0_3;
// case 5:
// k1 ^= ((long) access.u8(input, offset + 4L)) << 32;
// case 4:
// break fetch0_3;
// case 3:
// k1 ^= ((long) access.u8(input, offset + 2L)) << 16;
// case 2:
// k1 ^= (long) Primitives.nativeToLittleEndian(
// access.u16(input, offset));
// break megaSwitch;
// case 1:
// k1 ^= ((long) access.u8(input, offset));
// break megaSwitch;
// default:
// throw new AssertionError();
// }
// } // fetch0_3
// k1 ^= access.u32(input, offset);
// break megaSwitch;
// } // fetch8_11
// k2 ^= access.u32(input, offset + 8L);
// } // fetch0_7
// k1 ^= access.i64(input, offset);
// } // megaSwitch
//
// h1 ^= mixK1(k1);
// h2 ^= mixK2(k2);
// }
return finalize(length, h1, h2, result);
}
private static long finalize(long length, long h1, long h2, @Nullable long[] result) {
h1 ^= length;
h2 ^= length;
h1 += h2;
h2 += h1;
h1 = fmix64(h1);
h2 = fmix64(h2);
if (null != result) {
h1 += h2;
result[0] = h1;
result[1] = h1 + h2;
return h1;
} else {
return h1 + h2;
}
}
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;
}
private static class AsLongTupleHashFunction extends DualHashFunction {
private static final long serialVersionUID = 0L;
@NotNull
private static final AsLongTupleHashFunction SEEDLESS_INSTANCE = new AsLongTupleHashFunction();
@NotNull
private static final LongHashFunction SEEDLESS_INSTANCE_LONG = SEEDLESS_INSTANCE.asLongHashFunction();
private Object readResolve() {
return SEEDLESS_INSTANCE;
}
@Override
public int bitsLength() {
return 128;
}
@Override
@NotNull
public long[] newResultArray() {
return new long[2]; // override for a little performance
}
long seed() {
return 0L;
}
protected long hashNativeLong(long nativeLong, long len, @Nullable long[] result) {
long h1 = mixK1(nativeLong);
long h2 = 0L;
return MurmurHash_3.finalize(len, h1, h2, result);
}
@Override
public long dualHashLong(long input, @Nullable long[] result) {
return hashNativeLong(Primitives.nativeToLittleEndian(input), 8L, result);
}
@Override
public long dualHashInt(int input, @Nullable long[] result) {
return hashNativeLong(unsignedInt(Primitives.nativeToLittleEndian(input)), 4L, result);
}
@Override
public long dualHashShort(short input, @Nullable long[] result) {
return hashNativeLong(unsignedShort(Primitives.nativeToLittleEndian(input)), 2L, result);
}
@Override
public long dualHashChar(char input, @Nullable long[] result) {
return hashNativeLong(unsignedShort(Primitives.nativeToLittleEndian(input)), 2L, result);
}
@Override
public long dualHashByte(byte input, @Nullable long[] result) {
return hashNativeLong(Primitives.unsignedByte((int) input), 1L, result);
}
@Override
public long dualHashVoid(@Nullable long[] result) {
if (null != result) {
result[0] = 0;
result[1] = 0;
}
return 0;
}
@Override
public long dualHash(@Nullable T input, Access access, long off, long len, @Nullable long[] result) {
long seed = seed();
return MurmurHash_3.hash(seed, input, access.byteOrder(input, LITTLE_ENDIAN), off, len, result);
}
}
@NotNull
static LongTupleHashFunction asLongTupleHashFunctionWithoutSeed() {
return AsLongTupleHashFunction.SEEDLESS_INSTANCE;
}
@NotNull
static LongHashFunction asLongHashFunctionWithoutSeed() {
return AsLongTupleHashFunction.SEEDLESS_INSTANCE_LONG;
}
private static class AsLongTupleHashFunctionSeeded extends AsLongTupleHashFunction {
private static final long serialVersionUID = 0L;
private final long seed;
@NotNull
private final transient long[] voidHash = newResultArray();
private AsLongTupleHashFunctionSeeded(long seed) {
this.seed = seed;
MurmurHash_3.finalize(0L, seed, seed, voidHash);
}
@Override
long seed() {
return seed;
}
@Override
protected long hashNativeLong(long nativeLong, long len, @Nullable long[] result) {
long seed = this.seed;
long h1 = seed ^ mixK1(nativeLong);
long h2 = seed;
return MurmurHash_3.finalize(len, h1, h2, result);
}
@Override
public long dualHashVoid(@Nullable long[] result) {
if (null != result) {
result[0] = voidHash[0];
result[1] = voidHash[1];
}
return voidHash[0];
}
}
@NotNull
static LongTupleHashFunction asLongTupleHashFunctionWithSeed(long seed) {
return new AsLongTupleHashFunctionSeeded(seed);
}
@NotNull
static LongHashFunction asLongHashFunctionWithSeed(long seed) {
return new AsLongTupleHashFunctionSeeded(seed).asLongHashFunction();
}
}
