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}. */
advance(long time, TimeUnit 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}. */
advance(long 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    */
setAutoIncrementStep(long autoIncrementStep, TimeUnit timeUnit)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 
read()69   @Override public long read() {
70     return nanos.getAndAdd(autoIncrementStepNanos);
71   }
72 }
73