1 files changed, 126 insertions, 0 deletions
diff --git a/common/sketch/src/main/java/org/apache/spark/util/sketch/Murmur3_x86_32.java b/common/sketch/src/main/java/org/apache/spark/util/sketch/Murmur3_x86_32.java
new file mode 100644
index 0000000000..3d1f28bcb9
--- /dev/null
+++ b/common/sketch/src/main/java/org/apache/spark/util/sketch/Murmur3_x86_32.java
@@ -0,0 +1,126 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.spark.util.sketch;
+
+/**
+ * 32-bit Murmur3 hasher.  This is based on Guava's Murmur3_32HashFunction.
+ */
+// This class is duplicated from `org.apache.spark.unsafe.hash.Murmur3_x86_32` to make sure
+// spark-sketch has no external dependencies.
+final class Murmur3_x86_32 {
+  private static final int C1 = 0xcc9e2d51;
+  private static final int C2 = 0x1b873593;
+
+  private final int seed;
+
+  public Murmur3_x86_32(int seed) {
+    this.seed = seed;
+  }
+
+  @Override
+  public String toString() {
+    return "Murmur3_32(seed=" + seed + ")";
+  }
+
+  public int hashInt(int input) {
+    return hashInt(input, seed);
+  }
+
+  public static int hashInt(int input, int seed) {
+    int k1 = mixK1(input);
+    int h1 = mixH1(seed, k1);
+
+    return fmix(h1, 4);
+  }
+
+  public int hashUnsafeWords(Object base, long offset, int lengthInBytes) {
+    return hashUnsafeWords(base, offset, lengthInBytes, seed);
+  }
+
+  public static int hashUnsafeWords(Object base, long offset, int lengthInBytes, int seed) {
+    // This is based on Guava's `Murmur32_Hasher.processRemaining(ByteBuffer)` method.
+    assert (lengthInBytes % 8 == 0): "lengthInBytes must be a multiple of 8 (word-aligned)";
+    int h1 = hashBytesByInt(base, offset, lengthInBytes, seed);
+    return fmix(h1, lengthInBytes);
+  }
+
+  public static int hashUnsafeBytes(Object base, long offset, int lengthInBytes, int seed) {
+    assert (lengthInBytes >= 0): "lengthInBytes cannot be negative";
+    int lengthAligned = lengthInBytes - lengthInBytes % 4;
+    int h1 = hashBytesByInt(base, offset, lengthAligned, seed);
+    for (int i = lengthAligned; i < lengthInBytes; i++) {
+      int halfWord = Platform.getByte(base, offset + i);
+      int k1 = mixK1(halfWord);
+      h1 = mixH1(h1, k1);
+    }
+    return fmix(h1, lengthInBytes);
+  }
+
+  private static int hashBytesByInt(Object base, long offset, int lengthInBytes, int seed) {
+    assert (lengthInBytes % 4 == 0);
+    int h1 = seed;
+    for (int i = 0; i < lengthInBytes; i += 4) {
+      int halfWord = Platform.getInt(base, offset + i);
+      int k1 = mixK1(halfWord);
+      h1 = mixH1(h1, k1);
+    }
+    return h1;
+  }
+
+  public int hashLong(long input) {
+    return hashLong(input, seed);
+  }
+
+  public static int hashLong(long input, int seed) {
+    int low = (int) input;
+    int high = (int) (input >>> 32);
+
+    int k1 = mixK1(low);
+    int h1 = mixH1(seed, k1);
+
+    k1 = mixK1(high);
+    h1 = mixH1(h1, k1);
+
+    return fmix(h1, 8);
+  }
+
+  private static int mixK1(int k1) {
+    k1 *= C1;
+    k1 = Integer.rotateLeft(k1, 15);
+    k1 *= C2;
+    return k1;
+  }
+
+  private static int mixH1(int h1, int k1) {
+    h1 ^= k1;
+    h1 = Integer.rotateLeft(h1, 13);
+    h1 = h1 * 5 + 0xe6546b64;
+    return h1;
+  }
+
+  // Finalization mix - force all bits of a hash block to avalanche
+  private static int fmix(int h1, int length) {
+    h1 ^= length;
+    h1 ^= h1 >>> 16;
+    h1 *= 0x85ebca6b;
+    h1 ^= h1 >>> 13;
+    h1 *= 0xc2b2ae35;
+    h1 ^= h1 >>> 16;
+    return h1;
+  }
+}