/*
 * Copyright (C) 2014 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.util.concurrent;

import static java.util.concurrent.TimeUnit.NANOSECONDS;
import static java.util.concurrent.TimeUnit.SECONDS;

import com.google.caliper.BeforeExperiment;
import com.google.caliper.Benchmark;
import com.google.caliper.Param;
import com.google.caliper.api.VmOptions;
import com.google.common.util.concurrent.AbstractFutureBenchmarks.Facade;
import com.google.common.util.concurrent.AbstractFutureBenchmarks.Impl;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeoutException;

/** A benchmark that times how long it takes to add a given number of */
@VmOptions({"-Xms8g", "-Xmx8g"})
public class SingleThreadAbstractFutureBenchmark {
  @Param Impl impl;

  private final Exception exception = new Exception();
  private Facade<?> notDoneFuture;

  @BeforeExperiment
  void setUp() throws Exception {
    notDoneFuture = impl.newFacade();
  }

  @Benchmark
  public long timeComplete_Normal(int reps) throws Exception {
    long r = 0;
    List<Facade<Integer>> list = new ArrayList<>(reps);
    for (int i = 0; i < reps; i++) {
      final Facade<Integer> localFuture = impl.newFacade();
      list.add(localFuture);
      localFuture.set(i);
    }
    for (int i = 0; i < reps; i++) {
      r += list.get(i).get();
    }
    return r;
  }

  @Benchmark
  public long timeComplete_Failure(int reps) throws Exception {
    long r = 0;
    List<Facade<Integer>> list = new ArrayList<>(reps);
    for (int i = 0; i < reps; i++) {
      final Facade<Integer> localFuture = impl.newFacade();
      list.add(localFuture);
      localFuture.setException(exception);
    }
    for (int i = 0; i < reps; i++) {
      Facade<Integer> facade = list.get(i);
      try {
        facade.get();
        r++;
      } catch (ExecutionException e) {
        r += 2;
      }
    }
    return r;
  }

  @Benchmark
  public long timeComplete_Cancel(int reps) throws Exception {
    long r = 0;
    List<Facade<Integer>> list = new ArrayList<>(reps);
    for (int i = 0; i < reps; i++) {
      final Facade<Integer> localFuture = impl.newFacade();
      list.add(localFuture);
      localFuture.cancel(false);
    }
    for (int i = 0; i < reps; i++) {
      Facade<Integer> facade = list.get(i);
      try {
        facade.get();
        r++;
      } catch (CancellationException e) {
        r += 2;
      }
    }
    return r;
  }

  @Benchmark
  public long timeGetWith0Timeout(long reps) throws Exception {
    Facade<?> f = notDoneFuture;
    long r = 0;
    for (int i = 0; i < reps; i++) {
      try {
        f.get(0, SECONDS);
        r += 1;
      } catch (TimeoutException e) {
        r += 2;
      }
    }
    return r;
  }

  @Benchmark
  public long timeGetWithSmallTimeout(long reps) throws Exception {
    Facade<?> f = notDoneFuture;
    long r = 0;
    for (int i = 0; i < reps; i++) {
      try {
        f.get(500, NANOSECONDS);
        r += 1;
      } catch (TimeoutException e) {
        r += 2;
      }
    }
    return r;
  }
}
