1/*
2 * Copyright (C) 2008 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.testing;
18
19import static com.google.common.base.Preconditions.checkArgument;
20
21import com.google.common.annotations.Beta;
22import com.google.common.annotations.GwtCompatible;
23import com.google.common.base.Ticker;
24
25import java.util.concurrent.TimeUnit;
26import java.util.concurrent.atomic.AtomicLong;
27
28/**
29 * A Ticker whose value can be advanced programmatically in test.
30 * <p>
31 * The ticker can be configured so that the time is incremented whenever {@link #read} is called:
32 * see {@link #setAutoIncrementStep}.
33 * <p>
34 * This class is thread-safe.
35 *
36 * @author Jige Yu
37 * @since 10.0
38 */
39@Beta
40@GwtCompatible
41public class FakeTicker extends Ticker {
42
43  private final AtomicLong nanos = new AtomicLong();
44  private volatile long autoIncrementStepNanos;
45
46  /** Advances the ticker value by {@code time} in {@code timeUnit}. */
47  public FakeTicker advance(long time, TimeUnit timeUnit) {
48    return advance(timeUnit.toNanos(time));
49  }
50
51  /** Advances the ticker value by {@code nanoseconds}. */
52  public FakeTicker advance(long nanoseconds) {
53    nanos.addAndGet(nanoseconds);
54    return this;
55  }
56
57  /**
58   * Sets the increment applied to the ticker whenever it is queried.
59   *
60   * <p>The default behavior is to auto increment by zero. i.e: The ticker is left unchanged when
61   * queried.
62   */
63  public FakeTicker setAutoIncrementStep(long autoIncrementStep, TimeUnit timeUnit) {
64    checkArgument(autoIncrementStep >= 0, "May not auto-increment by a negative amount");
65    this.autoIncrementStepNanos = timeUnit.toNanos(autoIncrementStep);
66    return this;
67  }
68
69  @Override public long read() {
70    return nanos.getAndAdd(autoIncrementStepNanos);
71  }
72}
73