1 /*
2  * Copyright (C) 2018 The Android Open Source Project
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 android.os;
18 
19 import android.util.Log;
20 
21 import java.time.Clock;
22 import java.time.DateTimeException;
23 import java.time.ZoneId;
24 import java.util.Arrays;
25 
26 /**
27  * Single {@link Clock} that will return the best available time from a set of
28  * prioritized {@link Clock} instances.
29  * <p>
30  * For example, when {@link SystemClock#currentNetworkTimeClock()} isn't able to
31  * provide the time, this class could use {@link Clock#systemUTC()} instead.
32  *
33  * @hide
34  */
35 public class BestClock extends SimpleClock {
36     private static final String TAG = "BestClock";
37 
38     private final Clock[] clocks;
39 
BestClock(ZoneId zone, Clock... clocks)40     public BestClock(ZoneId zone, Clock... clocks) {
41         super(zone);
42         this.clocks = clocks;
43     }
44 
45     @Override
millis()46     public long millis() {
47         for (Clock clock : clocks) {
48             try {
49                 return clock.millis();
50             } catch (DateTimeException e) {
51                 // Ignore and attempt the next clock
52                 Log.w(TAG, e.toString());
53             }
54         }
55         throw new DateTimeException(
56                 "No clocks in " + Arrays.toString(clocks) + " were able to provide time");
57     }
58 }
59