/*
 * Copyright (C) 2010 The Guava Authors
 *
 * 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.google.common.primitives;

import com.google.caliper.Param;
import com.google.caliper.Runner;
import com.google.caliper.SimpleBenchmark;

import java.util.Arrays;
import java.util.Comparator;
import java.util.Random;

/**
 * Microbenchmark for {@link UnsignedBytes}.
 *
 * @author Hiroshi Yamauchi
 */
public class UnsignedBytesBenchmark extends SimpleBenchmark {

  private byte[] ba1;
  private byte[] ba2;
  private byte[] ba3;
  private byte[] ba4;
  private Comparator<byte[]> javaImpl;
  private Comparator<byte[]> unsafeImpl;

  // 4, 8, 64, 1K, 1M, 1M (unaligned), 64M, 64M (unaligned)
  //@Param({"4", "8", "64", "1024", "1048576", "1048577", "6710884", "6710883"})
  @Param({"4", "8", "64", "1024" })
  private int length;

  @Override
  protected void setUp() throws Exception {
    Random r = new Random();
    ba1 = new byte[length];
    r.nextBytes(ba1);
    ba2 = Arrays.copyOf(ba1, ba1.length);
    // Differ at the last element
    ba3 = Arrays.copyOf(ba1, ba1.length);
    ba4 = Arrays.copyOf(ba1, ba1.length);
    ba3[ba1.length - 1] = (byte) 43;
    ba4[ba1.length - 1] = (byte) 42;

    javaImpl = UnsignedBytes.lexicographicalComparatorJavaImpl();
    unsafeImpl =
        UnsignedBytes.LexicographicalComparatorHolder.UnsafeComparator.INSTANCE;
  }

  public void timeLongEqualJava(int reps) {
    for (int i = 0; i < reps; ++i) {
      if (javaImpl.compare(ba1, ba2) != 0) {
        throw new Error(); // deoptimization
      }
    }
  }

  public void timeLongEqualUnsafe(int reps) {
    for (int i = 0; i < reps; ++i) {
      if (unsafeImpl.compare(ba1, ba2) != 0) {
        throw new Error(); // deoptimization
      }
    }
  }

  public void timeDiffLastJava(int reps) {
    for (int i = 0; i < reps; ++i) {
      if (javaImpl.compare(ba3, ba4) == 0) {
        throw new Error(); // deoptimization
      }
    }
  }

  public void timeDiffLastUnsafe(int reps) {
    for (int i = 0; i < reps; ++i) {
      if (unsafeImpl.compare(ba3, ba4) == 0) {
        throw new Error(); // deoptimization
      }
    }
  }

  public static void main(String[] args) {
    /*
    try {
      UnsignedBytesBenchmark bench = new UnsignedBytesBenchmark();
      bench.length = 1024;
      bench.setUp();
      bench.timeUnsafe(100000);
    } catch (Exception e) {
    }*/
    Runner.main(UnsignedBytesBenchmark.class, args);
  }
}