basic implementation of PolymurHash 2.0

licenses/ZLIB_POLYMURHASH.txt

@@ -19,4 +19,4 @@ the following restrictions:
 2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
 
-3. This notice may not be removed or altered from any source distribution.
+3. This notice may not be removed or altered from any source distribution.

reference-implementations/polymur-hash_2_0/polymur-hash_2_0_checksum_config.cpp

@@ -23,9 +23,9 @@ void PolymurHash_2_0_ChecksumConfig::calculateHash(const uint8_t *seedBytes,
 	uint64_t seed0;
 	uint64_t seed1;
 	uint64_t tweak;
-	memcpy(&seed0, seedBytes, 8);
-	memcpy(&seed1, seedBytes + 8, 8);
-	memcpy(&tweak, seedBytes + 16, 8);
+	memcpy(&tweak, seedBytes, 8);
+	memcpy(&seed0, seedBytes + 8, 8);
+	memcpy(&seed1, seedBytes + 16, 8);
 	PolymurHashParams params0;
 	PolymurHashParams params1;
 

src/jmh/java/com/dynatrace/hash4j/hashing/PolymurHash2_0PerformanceTest.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2022-2023 Dynatrace LLC
+ *
+ * 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 com.dynatrace.hash4j.hashing;
+
+public class PolymurHash2_0PerformanceTest extends AbstactHasher64PerformanceTest {
+
+  private static final Hasher64 HASHER_INSTANCE =
+      Hashing.polymurHash2_0(0x2afe2c5c76d4017eL, 0x46223142eceb1893L);
+
+  @Override
+  protected Hasher64 getHasherInstance() {
+    return HASHER_INSTANCE;
+  }
+}

src/main/java/com/dynatrace/hash4j/hashing/AbstractKomihash.java

@@ -341,10 +341,5 @@ public long getAsLong() {
 
       return finalizeGetAsLong(se1, se5, off, len);
     }
-
-    @Override
-    public int getHashBitSize() {
-      return 64;
-    }
   }
 }

src/main/java/com/dynatrace/hash4j/hashing/AbstractWyhashFinal.java

@@ -519,10 +519,5 @@ public long getAsLong() {
       }
       return finish(a, b, s, byteCount);
     }
-
-    @Override
-    public int getHashBitSize() {
-      return 64;
-    }
   }
 }

src/main/java/com/dynatrace/hash4j/hashing/Hashing.java

@@ -150,6 +150,41 @@ public static Hasher64 komihash5_0(long seed) {
     return Komihash5_0.create(seed);
   }
 
+  /**
+   * Returns a {@link Hasher64} implementing the 64-bit PolymurHash (version 2.0) algorithm using
+   * the given tweak and seed value.
+   *
+   * <p>This implementation is compatible with the C++ reference implementation of {@code
+   * polymur_hash} defined in <a
+   * href="https://github.com/orlp/polymur-hash/blob/c6cc6884459560443e696604e9db3b6bb61a9bfa/polymur-hash.h">polymur-hash.h</a>
+   * on an Intel x86 architecture.
+   *
+   * @param tweak a 64-bit tweak
+   * @param seed a 64-bit seed
+   * @return a hasher instance
+   */
+  public static Hasher64 polymurHash2_0(long tweak, long seed) {
+    return PolymurHash2_0.create(tweak, seed);
+  }
+
+  /**
+   * Returns a {@link Hasher64} implementing the 64-bit PolymurHash (version 2.0) algorithm using
+   * the given tweak and seed values.
+   *
+   * <p>This implementation is compatible with the C++ reference implementation of {@code
+   * polymur_hash} defined in <a
+   * href="https://github.com/orlp/polymur-hash/blob/c6cc6884459560443e696604e9db3b6bb61a9bfa/polymur-hash.h">polymur-hash.h</a>
+   * on an Intel x86 architecture.
+   *
+   * @param tweak a 64-bit tweak
+   * @param kSeed a 64-bit kSeed
+   * @param sSeed a 64-bit kSeed
+   * @return a hasher instance
+   */
+  public static Hasher64 polymurHash2_0(long tweak, long kSeed, long sSeed) {
+    return PolymurHash2_0.create(tweak, kSeed, sSeed);
+  }
+
   /**
    * Returns a {@link Hasher64} implementing the 64-bit Wyhash (version final 3) algorithm using a
    * seed value of zero and the default secret.