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 java.nio.ByteOrder;
  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 the XXH64 function.
   * <p/>
   * Test constants were taken from the original implementation and the airlift/slice implementation.
   */
  public class XXH64Suite {
  
    private static final XXH64 hasher = new XXH64(0);
  
    private static final int SIZE = 101;
    private static final long PRIME = 2654435761L;
    private static final byte[] BUFFER = new byte[SIZE];
    private static final int TEST_INT = 0x4B1FFF9E; // First 4 bytes in the buffer
    private static final long TEST_LONG = 0xDD2F535E4B1FFF9EL; // First 8 bytes in the buffer
  
    /* Create the test data. */
    static {
      long seed = PRIME;
      for (int i = 0; i < SIZE; i++) {
        BUFFER[i] = (byte) (seed >> 24);
        seed *= seed;
      }
    }
  
    @Test
    public void testKnownIntegerInputs() {
      Assert.assertEquals(0x9256E58AA397AEF1L, hasher.hashInt(TEST_INT));
      Assert.assertEquals(0x9D5FFDFB928AB4BL, XXH64.hashInt(TEST_INT, PRIME));
    }
  
    @Test
    public void testKnownLongInputs() {
      Assert.assertEquals(0xF74CB1451B32B8CFL, hasher.hashLong(TEST_LONG));
      Assert.assertEquals(0x9C44B77FBCC302C5L, XXH64.hashLong(TEST_LONG, PRIME));
    }
  
    @Test
    public void testKnownByteArrayInputs() {
      Assert.assertEquals(0xEF46DB3751D8E999L,
              hasher.hashUnsafeBytes(BUFFER, Platform.BYTE_ARRAY_OFFSET, 0));
      Assert.assertEquals(0xAC75FDA2929B17EFL,
              XXH64.hashUnsafeBytes(BUFFER, Platform.BYTE_ARRAY_OFFSET, 0, PRIME));
      Assert.assertEquals(0x4FCE394CC88952D8L,
              hasher.hashUnsafeBytes(BUFFER, Platform.BYTE_ARRAY_OFFSET, 1));
      Assert.assertEquals(0x739840CB819FA723L,
              XXH64.hashUnsafeBytes(BUFFER, Platform.BYTE_ARRAY_OFFSET, 1, PRIME));
  
      // These tests currently fail in a big endian environment because the test data and expected
      // answers are generated with little endian the assumptions. We could revisit this when Platform
      // becomes endian aware.
      if (ByteOrder.nativeOrder() == ByteOrder.LITTLE_ENDIAN) {
        Assert.assertEquals(0x9256E58AA397AEF1L,
                hasher.hashUnsafeBytes(BUFFER, Platform.BYTE_ARRAY_OFFSET, 4));
        Assert.assertEquals(0x9D5FFDFB928AB4BL,
                XXH64.hashUnsafeBytes(BUFFER, Platform.BYTE_ARRAY_OFFSET, 4, PRIME));
        Assert.assertEquals(0xF74CB1451B32B8CFL,
                hasher.hashUnsafeBytes(BUFFER, Platform.BYTE_ARRAY_OFFSET, 8));
        Assert.assertEquals(0x9C44B77FBCC302C5L,
                XXH64.hashUnsafeBytes(BUFFER, Platform.BYTE_ARRAY_OFFSET, 8, PRIME));
        Assert.assertEquals(0xCFFA8DB881BC3A3DL,
                hasher.hashUnsafeBytes(BUFFER, Platform.BYTE_ARRAY_OFFSET, 14));
        Assert.assertEquals(0x5B9611585EFCC9CBL,
                XXH64.hashUnsafeBytes(BUFFER, Platform.BYTE_ARRAY_OFFSET, 14, PRIME));
        Assert.assertEquals(0x0EAB543384F878ADL,
                hasher.hashUnsafeBytes(BUFFER, Platform.BYTE_ARRAY_OFFSET, SIZE));
        Assert.assertEquals(0xCAA65939306F1E21L,
                XXH64.hashUnsafeBytes(BUFFER, Platform.BYTE_ARRAY_OFFSET, SIZE, PRIME));
      }
    }
  
    @Test
    public void randomizedStressTest() {
      int size = 65536;
      Random rand = new Random();
  
      // A set used to track collision rate.
      Set<Long> 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 * 0.95d);
    }
  
    @Test
    public void randomizedStressTestBytes() {
      int size = 65536;
      Random rand = new Random();
  
      // A set used to track collision rate.
      Set<Long> 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 * 0.95d);
    }
  
    @Test
    public void randomizedStressTestPaddedStrings() {
      int size = 64000;
      // A set used to track collision rate.
      Set<Long> 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 * 0.95d);
    }
  }
  