1/*
2 * Copyright (C) 2011 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.util;
18
19/**
20 * Interface that provides trusted time information, possibly coming from an NTP
21 * server. Implementations may cache answers until {@link #forceRefresh()}.
22 *
23 * @hide
24 */
25public interface TrustedTime {
26    /**
27     * Force update with an external trusted time source, returning {@code true}
28     * when successful.
29     */
30    public boolean forceRefresh();
31
32    /**
33     * Check if this instance has cached a response from a trusted time source.
34     */
35    public boolean hasCache();
36
37    /**
38     * Return time since last trusted time source contact, or
39     * {@link Long#MAX_VALUE} if never contacted.
40     */
41    public long getCacheAge();
42
43    /**
44     * Return certainty of cached trusted time in milliseconds, or
45     * {@link Long#MAX_VALUE} if never contacted. Smaller values are more
46     * precise.
47     */
48    public long getCacheCertainty();
49
50    /**
51     * Return current time similar to {@link System#currentTimeMillis()},
52     * possibly using a cached authoritative time source.
53     */
54    public long currentTimeMillis();
55}
56