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.sql.catalyst.expressions;
  
  import org.apache.spark.unsafe.Platform;
  import org.apache.spark.unsafe.types.UTF8String;
  import org.junit.Assert;
  import org.junit.Test;
  
  import java.nio.charset.StandardCharsets;
  import java.util.HashSet;
  import java.util.Random;
  import java.util.Set;
  
  public class HiveHasherSuite {
    private final static HiveHasher hasher = new HiveHasher();
  
    @Test
    public void testKnownIntegerInputs() {
      int[] inputs = {0, Integer.MIN_VALUE, Integer.MAX_VALUE, 593689054, -189366624};
      for (int input : inputs) {
        Assert.assertEquals(input, HiveHasher.hashInt(input));
      }
    }
  
    @Test
    public void testKnownLongInputs() {
      Assert.assertEquals(0, HiveHasher.hashLong(0L));
      Assert.assertEquals(41, HiveHasher.hashLong(-42L));
      Assert.assertEquals(42, HiveHasher.hashLong(42L));
      Assert.assertEquals(-2147483648, HiveHasher.hashLong(Long.MIN_VALUE));
      Assert.assertEquals(-2147483648, HiveHasher.hashLong(Long.MAX_VALUE));
    }
  
    @Test
    public void testKnownStringAndIntInputs() {
      int[] inputs = {84, 19, 8};
      int[] expected = {-823832826, -823835053, 111972242};
  
      for (int i = 0; i < inputs.length; i++) {
        UTF8String s = UTF8String.fromString("val_" + inputs[i]);
        int hash = HiveHasher.hashUnsafeBytes(s.getBaseObject(), s.getBaseOffset(), s.numBytes());
        Assert.assertEquals(expected[i], ((31 * inputs[i]) + hash));
      }
    }
  
    @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(HiveHasher.hashInt(vint), HiveHasher.hashInt(vint));
        Assert.assertEquals(HiveHasher.hashLong(lint), HiveHasher.hashLong(lint));
  
        hashcodes.add(HiveHasher.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(
            HiveHasher.hashUnsafeBytes(bytes, Platform.BYTE_ARRAY_OFFSET, byteArrSize),
            HiveHasher.hashUnsafeBytes(bytes, Platform.BYTE_ARRAY_OFFSET, byteArrSize));
  
        hashcodes.add(HiveHasher.hashUnsafeBytes(
            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(
            HiveHasher.hashUnsafeBytes(paddedBytes, Platform.BYTE_ARRAY_OFFSET, byteArrSize),
            HiveHasher.hashUnsafeBytes(paddedBytes, Platform.BYTE_ARRAY_OFFSET, byteArrSize));
  
        hashcodes.add(HiveHasher.hashUnsafeBytes(
            paddedBytes, Platform.BYTE_ARRAY_OFFSET, byteArrSize));
      }
  
      // A very loose bound.
      Assert.assertTrue(hashcodes.size() > size * 0.95);
    }
  }
  