1 /*
2  * Copyright 2017, OpenCensus 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 io.opencensus.internal;
18 
19 import io.opencensus.common.Clock;
20 import io.opencensus.common.Timestamp;
21 import javax.annotation.concurrent.Immutable;
22 
23 /** A {@link Clock} that always returns 0. */
24 @Immutable
25 public final class ZeroTimeClock extends Clock {
26   private static final ZeroTimeClock INSTANCE = new ZeroTimeClock();
27   private static final Timestamp ZERO_TIMESTAMP = Timestamp.create(0, 0);
28 
ZeroTimeClock()29   private ZeroTimeClock() {}
30 
31   /**
32    * Returns a {@code ZeroTimeClock}.
33    *
34    * @return a {@code ZeroTimeClock}.
35    */
getInstance()36   public static ZeroTimeClock getInstance() {
37     return INSTANCE;
38   }
39 
40   @Override
now()41   public Timestamp now() {
42     return ZERO_TIMESTAMP;
43   }
44 
45   @Override
nowNanos()46   public long nowNanos() {
47     return 0;
48   }
49 }
50