1 /*
2  * Copyright (C) 2019 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 package com.android.settings.dashboard;
17 
18 import android.database.ContentObserver;
19 import android.net.Uri;
20 import android.os.Handler;
21 import android.os.Looper;
22 
23 import com.android.settingslib.utils.ThreadUtils;
24 
25 import java.util.concurrent.CountDownLatch;
26 
27 /**
28  * Observer for updating injected dynamic data.
29  */
30 public abstract class DynamicDataObserver extends ContentObserver {
31 
32     private Runnable mUpdateRunnable;
33     private CountDownLatch mCountDownLatch;
34     private boolean mUpdateDelegated;
35 
DynamicDataObserver()36     protected DynamicDataObserver() {
37         super(new Handler(Looper.getMainLooper()));
38         mCountDownLatch = new CountDownLatch(1);
39         // Load data for the first time
40         onDataChanged();
41     }
42 
43     /** Returns the uri of the callback. */
getUri()44     public abstract Uri getUri();
45 
46     /** Called when data changes. */
onDataChanged()47     public abstract void onDataChanged();
48 
49     /** Calls the runnable to update UI */
updateUi()50     public synchronized void updateUi() {
51         mUpdateDelegated = true;
52         if (mUpdateRunnable != null) {
53             mUpdateRunnable.run();
54         }
55     }
56 
57     /** Returns the count-down latch */
getCountDownLatch()58     public CountDownLatch getCountDownLatch() {
59         return mCountDownLatch;
60     }
61 
62     @Override
onChange(boolean selfChange)63     public void onChange(boolean selfChange) {
64         onDataChanged();
65     }
66 
post(Runnable runnable)67     protected synchronized void post(Runnable runnable) {
68         if (mUpdateDelegated) {
69             ThreadUtils.postOnMainThread(runnable);
70         } else {
71             mUpdateRunnable = runnable;
72             mCountDownLatch.countDown();
73         }
74     }
75 }
76