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
17package android.os;
18
19import android.util.Log;
20
21import java.time.Clock;
22import java.time.DateTimeException;
23import java.time.ZoneId;
24import 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 */
35public class BestClock extends SimpleClock {
36    private static final String TAG = "BestClock";
37
38    private final Clock[] clocks;
39
40    public BestClock(ZoneId zone, Clock... clocks) {
41        super(zone);
42        this.clocks = clocks;
43    }
44
45    @Override
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