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  
17  package com.google.common.testing;
18  
19  import static com.google.common.base.Preconditions.checkArgument;
20  
21  import com.google.common.annotations.Beta;
22  import com.google.common.annotations.GwtCompatible;
23  import com.google.common.base.Ticker;
24  
25  import java.util.concurrent.TimeUnit;
26  import 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
41  public 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  }