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 
17 package 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  */
25 public interface TrustedTime {
26     /**
27      * Force update with an external trusted time source, returning {@code true}
28      * when successful.
29      */
forceRefresh()30     public boolean forceRefresh();
31 
32     /**
33      * Check if this instance has cached a response from a trusted time source.
34      */
hasCache()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      */
getCacheAge()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      */
getCacheCertainty()48     public long getCacheCertainty();
49 
50     /**
51      * Return current time similar to {@link System#currentTimeMillis()},
52      * possibly using a cached authoritative time source.
53      */
currentTimeMillis()54     public long currentTimeMillis();
55 }
56