1/*
2 * Copyright (C) 2011 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.common.cache;
18
19import static com.google.common.base.Preconditions.checkState;
20
21import com.google.caliper.BeforeExperiment;
22import com.google.caliper.Benchmark;
23import com.google.caliper.Param;
24import com.google.common.cache.LocalCache.ReferenceEntry;
25import com.google.common.cache.LocalCache.Segment;
26
27import java.util.concurrent.atomic.AtomicReferenceArray;
28
29/**
30 * Benchmark for {@code LocalCache.Segment.expand()}.
31 *
32 * @author Charles Fry
33 */
34public class SegmentBenchmark {
35
36  @Param({"16", "32", "64", "128", "256", "512", "1024", "2048", "4096", "8192"}) int capacity;
37
38  private Segment<Object, Object> segment;
39
40  @BeforeExperiment
41  void setUp() {
42    LocalCache<Object, Object> cache = new LocalCache<Object, Object>(
43        CacheBuilder.newBuilder()
44            .concurrencyLevel(1)
45            .initialCapacity(capacity), null);
46    checkState(cache.segments.length == 1);
47    segment = cache.segments[0];
48    checkState(segment.table.length() == capacity);
49    for (int i = 0; i < segment.threshold; i++) {
50      cache.put(new Object(), new Object());
51    }
52    checkState(segment.table.length() == capacity);
53  }
54
55  @Benchmark int time(int reps) {
56    int dummy = 0;
57    AtomicReferenceArray<ReferenceEntry<Object, Object>> oldTable = segment.table;
58    for (int i = 0; i < reps; i++) {
59      segment.expand();
60      segment.table = oldTable;
61      dummy += segment.count;
62    }
63    return dummy;
64  }
65}
66