Java example source code file (SegmentBenchmark.java)

This example Java source code file (SegmentBenchmark.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

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Java - Java tags/keywords

atomicreferencearray, beforeexperiment, benchmark, localcache, object, param, segment, segmentbenchmark

The SegmentBenchmark.java Java example source code

/*
 * Copyright (C) 2011 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.cache;

import static com.google.common.base.Preconditions.checkState;

import com.google.caliper.BeforeExperiment;
import com.google.caliper.Benchmark;
import com.google.caliper.Param;
import com.google.common.cache.LocalCache.ReferenceEntry;
import com.google.common.cache.LocalCache.Segment;

import java.util.concurrent.atomic.AtomicReferenceArray;

/**
 * Benchmark for {@code LocalCache.Segment.expand()}.
 *
 * @author Charles Fry
 */
public class SegmentBenchmark {

  @Param({"16", "32", "64", "128", "256", "512", "1024", "2048", "4096", "8192"}) int capacity;

  private Segment<Object, Object> segment;

  @BeforeExperiment
  void setUp() {
    LocalCache<Object, Object> cache = new LocalCache(
        CacheBuilder.newBuilder()
            .concurrencyLevel(1)
            .initialCapacity(capacity), null);
    checkState(cache.segments.length == 1);
    segment = cache.segments[0];
    checkState(segment.table.length() == capacity);
    for (int i = 0; i < segment.threshold; i++) {
      cache.put(new Object(), new Object());
    }
    checkState(segment.table.length() == capacity);
  }

  @Benchmark int time(int reps) {
    int dummy = 0;
    AtomicReferenceArray<ReferenceEntry oldTable = segment.table;
    for (int i = 0; i < reps; i++) {
      segment.expand();
      segment.table = oldTable;
      dummy += segment.count;
    }
    return dummy;
  }
}