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      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 }
     73