content: /*
   * 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.unsafe.hash;
  
  import java.nio.charset.StandardCharsets;
  import java.util.HashSet;
  import java.util.Random;
  import java.util.Set;
  
  import org.apache.spark.unsafe.Platform;
  import org.junit.Assert;
  import org.junit.Test;
  
  /**
   * Test file based on Guava's Murmur3Hash32Test.
   */
  public class Murmur3_x86_32Suite {
  
    private static final Murmur3_x86_32 hasher = new Murmur3_x86_32(0);
  
    @Test
    public void testKnownIntegerInputs() {
      Assert.assertEquals(593689054, hasher.hashInt(0));
      Assert.assertEquals(-189366624, hasher.hashInt(-42));
      Assert.assertEquals(-1134849565, hasher.hashInt(42));
      Assert.assertEquals(-1718298732, hasher.hashInt(Integer.MIN_VALUE));
      Assert.assertEquals(-1653689534, hasher.hashInt(Integer.MAX_VALUE));
    }
  
    @Test
    public void testKnownLongInputs() {
      Assert.assertEquals(1669671676, hasher.hashLong(0L));
      Assert.assertEquals(-846261623, hasher.hashLong(-42L));
      Assert.assertEquals(1871679806, hasher.hashLong(42L));
      Assert.assertEquals(1366273829, hasher.hashLong(Long.MIN_VALUE));
      Assert.assertEquals(-2106506049, hasher.hashLong(Long.MAX_VALUE));
    }
  
    @Test
    public void randomizedStressTest() {
      int size = 65536;
      Random rand = new Random();
  
      // A set used to track collision rate.
      Set<Integer> hashcodes = new HashSet<>();
      for (int i = 0; i < size; i++) {
        int vint = rand.nextInt();
        long lint = rand.nextLong();
        Assert.assertEquals(hasher.hashInt(vint), hasher.hashInt(vint));
        Assert.assertEquals(hasher.hashLong(lint), hasher.hashLong(lint));
  
        hashcodes.add(hasher.hashLong(lint));
      }
  
      // A very loose bound.
      Assert.assertTrue(hashcodes.size() > size * 0.95);
    }
  
    @Test
    public void randomizedStressTestBytes() {
      int size = 65536;
      Random rand = new Random();
  
      // A set used to track collision rate.
      Set<Integer> hashcodes = new HashSet<>();
      for (int i = 0; i < size; i++) {
        int byteArrSize = rand.nextInt(100) * 8;
        byte[] bytes = new byte[byteArrSize];
        rand.nextBytes(bytes);
  
        Assert.assertEquals(
          hasher.hashUnsafeWords(bytes, Platform.BYTE_ARRAY_OFFSET, byteArrSize),
          hasher.hashUnsafeWords(bytes, Platform.BYTE_ARRAY_OFFSET, byteArrSize));
  
        hashcodes.add(hasher.hashUnsafeWords(
          bytes, Platform.BYTE_ARRAY_OFFSET, byteArrSize));
      }
  
      // A very loose bound.
      Assert.assertTrue(hashcodes.size() > size * 0.95);
    }
  
    @Test
    public void randomizedStressTestPaddedStrings() {
      int size = 64000;
      // A set used to track collision rate.
      Set<Integer> hashcodes = new HashSet<>();
      for (int i = 0; i < size; i++) {
        int byteArrSize = 8;
        byte[] strBytes = String.valueOf(i).getBytes(StandardCharsets.UTF_8);
        byte[] paddedBytes = new byte[byteArrSize];
        System.arraycopy(strBytes, 0, paddedBytes, 0, strBytes.length);
  
        Assert.assertEquals(
          hasher.hashUnsafeWords(paddedBytes, Platform.BYTE_ARRAY_OFFSET, byteArrSize),
          hasher.hashUnsafeWords(paddedBytes, Platform.BYTE_ARRAY_OFFSET, byteArrSize));
  
        hashcodes.add(hasher.hashUnsafeWords(
          paddedBytes, Platform.BYTE_ARRAY_OFFSET, byteArrSize));
      }
  
      // A very loose bound.
      Assert.assertTrue(hashcodes.size() > size * 0.95);
    }
  }
  