io.polaris.core.hash.MurmurHash Maven / Gradle / Ivy
package io.polaris.core.hash;
import io.polaris.core.lang.primitive.Bytes;
import java.nio.ByteOrder;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
/**
* Murmur3 32bit、64bit、128bit 哈希算法实现
* 此算法来自于：https://github.com/xlturing/Simhash4J/blob/master/src/main/java/bee/simhash/main/Murmur3.java
*
*
* 32-bit Java port of https://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp#94
* 128-bit Java port of https://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp#255
*
*
* @author looly, Simhash4J
* @author Qt
* @since 1.8, Aug 01, 2023
*/
public class MurmurHash {
// region Constants for 32 bit variant
private static final int C1_32 = 0xcc9e2d51;
private static final int C2_32 = 0x1b873593;
private static final int R1_32 = 15;
private static final int R2_32 = 13;
private static final int M_32 = 5;
private static final int N_32 = 0xe6546b64;
// endregion
// region Constants for 128 bit variant
private static final long C1 = 0x87c37b91114253d5L;
private static final long C2 = 0x4cf5ad432745937fL;
private static final int R1 = 31;
private static final int R2 = 27;
private static final int R3 = 33;
private static final int M = 5;
private static final int N1 = 0x52dce729;
private static final int N2 = 0x38495ab5;
// endregion
private static final int DEFAULT_SEED = 0;
private static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8;
private static final ByteOrder DEFAULT_ORDER = ByteOrder.LITTLE_ENDIAN;
/**
* Murmur3 32-bit Hash值计算
*
* @param data 数据
* @return Hash值
*/
public static int hash32(CharSequence data) {
return hash32(data.toString().getBytes(DEFAULT_CHARSET));
}
/**
* Murmur3 32-bit Hash值计算
*
* @param data 数据
* @return Hash值
*/
public static int hash32(byte[] data) {
return hash32(data, data.length, DEFAULT_SEED);
}
/**
* Murmur3 32-bit Hash值计算
*
* @param data 数据
* @param length 长度
* @param seed 种子，默认0
* @return Hash值
*/
public static int hash32(byte[] data, int length, int seed) {
return hash32(data, 0, length, seed);
}
/**
* Murmur3 32-bit Hash值计算
*
* @param data 数据
* @param offset 数据开始位置
* @param length 长度
* @param seed 种子，默认0
* @return Hash值
*/
public static int hash32(byte[] data, int offset, int length, int seed) {
int hash = seed;
final int nblocks = length >> 2;
// body
for (int i = 0; i < nblocks; i++) {
final int i4 = offset + (i << 2);
final int k = Bytes.bytesToInt(data, i4, DEFAULT_ORDER);
// mix functions
hash = mix32(k, hash);
}
// tail
final int idx = offset + (nblocks << 2);
int k1 = 0;
switch (offset + length - idx) {
case 3:
k1 ^= (data[idx + 2] & 0xff) << 16;
case 2:
k1 ^= (data[idx + 1] & 0xff) << 8;
case 1:
k1 ^= (data[idx] & 0xff);
// mix functions
k1 *= C1_32;
k1 = Integer.rotateLeft(k1, R1_32);
k1 *= C2_32;
hash ^= k1;
}
// finalization
hash ^= length;
return fmix32(hash);
}
/**
* Murmur3 64-bit Hash值计算
*
* @param data 数据
* @return Hash值
*/
public static long hash64(CharSequence data) {
return hash64(data.toString().getBytes(DEFAULT_CHARSET));
}
/**
* Murmur3 64-bit 算法
* This is essentially MSB 8 bytes of Murmur3 128-bit variant.
*
* @param data 数据
* @return Hash值
*/
public static long hash64(byte[] data) {
return hash64(data, data.length, DEFAULT_SEED);
}
/**
* 类Murmur3 64-bit 算法
* This is essentially MSB 8 bytes of Murmur3 128-bit variant.
*
* @param data 数据
* @param length 长度
* @param seed 种子，默认0
* @return Hash值
*/
public static long hash64(byte[] data, int length, int seed) {
long hash = seed;
final int nblocks = length >> 3;
// body
for (int i = 0; i < nblocks; i++) {
final int i8 = i << 3;
long k = Bytes.bytesToLong(data, i8, DEFAULT_ORDER);
// mix functions
k *= C1;
k = Long.rotateLeft(k, R1);
k *= C2;
hash ^= k;
hash = Long.rotateLeft(hash, R2) * M + N1;
}
// tail
long k1 = 0;
int tailStart = nblocks << 3;
switch (length - tailStart) {
case 7:
k1 ^= ((long) data[tailStart + 6] & 0xff) << 48;
case 6:
k1 ^= ((long) data[tailStart + 5] & 0xff) << 40;
case 5:
k1 ^= ((long) data[tailStart + 4] & 0xff) << 32;
case 4:
k1 ^= ((long) data[tailStart + 3] & 0xff) << 24;
case 3:
k1 ^= ((long) data[tailStart + 2] & 0xff) << 16;
case 2:
k1 ^= ((long) data[tailStart + 1] & 0xff) << 8;
case 1:
k1 ^= ((long) data[tailStart] & 0xff);
k1 *= C1;
k1 = Long.rotateLeft(k1, R1);
k1 *= C2;
hash ^= k1;
}
// finalization
hash ^= length;
hash = fmix64(hash);
return hash;
}
/**
* Murmur3 128-bit Hash值计算
*
* @param data 数据
* @return Hash值 (2 longs)
*/
public static long[] hash128(CharSequence data) {
return hash128(data.toString().getBytes(DEFAULT_CHARSET));
}
/**
* Murmur3 128-bit 算法.
*
* @param data -数据
* @return Hash值 (2 longs)
*/
public static long[] hash128(byte[] data) {
return hash128(data, data.length, DEFAULT_SEED);
}
/**
* Murmur3 128-bit variant.
*
* @param data 数据
* @param length 长度
* @param seed 种子，默认0
* @return Hash值(2 longs)
*/
public static long[] hash128(byte[] data, int length, int seed) {
return hash128(data, 0, length, seed);
}
/**
* Murmur3 128-bit variant.
*
* @param data 数据
* @param offset 数据开始位置
* @param length 长度
* @param seed 种子，默认0
* @return Hash值(2 longs)
*/
public static long[] hash128(byte[] data, int offset, int length, int seed) {
// 避免负数的种子
seed &= 0xffffffffL;
long h1 = seed;
long h2 = seed;
final int nblocks = length >> 4;
// body
for (int i = 0; i < nblocks; i++) {
final int i16 = offset + (i << 4);
long k1 = Bytes.bytesToLong(data, i16, DEFAULT_ORDER);
long k2 = Bytes.bytesToLong(data, i16 + 8, DEFAULT_ORDER);
// mix functions for k1
k1 *= C1;
k1 = Long.rotateLeft(k1, R1);
k1 *= C2;
h1 ^= k1;
h1 = Long.rotateLeft(h1, R2);
h1 += h2;
h1 = h1 * M + N1;
// mix functions for k2
k2 *= C2;
k2 = Long.rotateLeft(k2, R3);
k2 *= C1;
h2 ^= k2;
h2 = Long.rotateLeft(h2, R1);
h2 += h1;
h2 = h2 * M + N2;
}
// tail
long k1 = 0;
long k2 = 0;
final int tailStart = offset + (nblocks << 4);
switch (offset + length - tailStart) {
case 15:
k2 ^= (long) (data[tailStart + 14] & 0xff) << 48;
case 14:
k2 ^= (long) (data[tailStart + 13] & 0xff) << 40;
case 13:
k2 ^= (long) (data[tailStart + 12] & 0xff) << 32;
case 12:
k2 ^= (long) (data[tailStart + 11] & 0xff) << 24;
case 11:
k2 ^= (long) (data[tailStart + 10] & 0xff) << 16;
case 10:
k2 ^= (long) (data[tailStart + 9] & 0xff) << 8;
case 9:
k2 ^= data[tailStart + 8] & 0xff;
k2 *= C2;
k2 = Long.rotateLeft(k2, R3);
k2 *= C1;
h2 ^= k2;
case 8:
k1 ^= (long) (data[tailStart + 7] & 0xff) << 56;
case 7:
k1 ^= (long) (data[tailStart + 6] & 0xff) << 48;
case 6:
k1 ^= (long) (data[tailStart + 5] & 0xff) << 40;
case 5:
k1 ^= (long) (data[tailStart + 4] & 0xff) << 32;
case 4:
k1 ^= (long) (data[tailStart + 3] & 0xff) << 24;
case 3:
k1 ^= (long) (data[tailStart + 2] & 0xff) << 16;
case 2:
k1 ^= (long) (data[tailStart + 1] & 0xff) << 8;
case 1:
k1 ^= data[tailStart] & 0xff;
k1 *= C1;
k1 = Long.rotateLeft(k1, R1);
k1 *= C2;
h1 ^= k1;
}
// finalization
h1 ^= length;
h2 ^= length;
h1 += h2;
h2 += h1;
h1 = fmix64(h1);
h2 = fmix64(h2);
h1 += h2;
h2 += h1;
return new long[]{h1, h2};
}
private static int mix32(int k, int hash) {
k *= C1_32;
k = Integer.rotateLeft(k, R1_32);
k *= C2_32;
hash ^= k;
return Integer.rotateLeft(hash, R2_32) * M_32 + N_32;
}
private static int fmix32(int hash) {
hash ^= (hash >>> 16);
hash *= 0x85ebca6b;
hash ^= (hash >>> 13);
hash *= 0xc2b2ae35;
hash ^= (hash >>> 16);
return hash;
}
private static long fmix64(long h) {
h ^= (h >>> 33);
h *= 0xff51afd7ed558ccdL;
h ^= (h >>> 33);
h *= 0xc4ceb9fe1a85ec53L;
h ^= (h >>> 33);
return h;
}
}