1 /*
2  * Copyright (C) 2017 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 com.android.providers.tv;
18 
19 import android.content.Context;
20 import android.content.SharedPreferences;
21 import android.database.sqlite.SQLiteDatabase;
22 import android.media.tv.TvContract.Channels;
23 import android.media.tv.TvContract.PreviewPrograms;
24 import android.media.tv.TvContract.WatchNextPrograms;
25 import android.preference.PreferenceManager;
26 import android.provider.Settings;
27 
28 import com.android.internal.annotations.VisibleForTesting;
29 import com.android.providers.tv.TvProvider.DatabaseHelper;
30 
31 /**
32  * Convenient class for deleting transient rows. This ensures that the clean up job is done only
33  * once after boot.
34  */
35 public class TransientRowHelper {
36     private static final String PREF_KEY_LAST_DELETION_BOOT_COUNT =
37             "pref_key_last_deletion_boot_count";
38     private static TransientRowHelper sInstance;
39 
40     private Context mContext;
41     private DatabaseHelper mDatabaseHelper;
42     @VisibleForTesting
43     protected boolean mTransientRowsDeleted;
44 
45     /**
46      * Returns the singleton TransientRowHelper instance.
47      *
48      * @param context The application context.
49      */
getInstance(Context context)50     public static TransientRowHelper getInstance(Context context) {
51         synchronized (TransientRowHelper.class) {
52             if (sInstance == null) {
53                 sInstance = new TransientRowHelper(context);
54             }
55         }
56         return sInstance;
57     }
58 
59     @VisibleForTesting
TransientRowHelper(Context context)60     TransientRowHelper(Context context) {
61         mContext = context;
62         mDatabaseHelper = DatabaseHelper.getInstance(context);
63     }
64 
65     @VisibleForTesting
TransientRowHelper(Context context, DatabaseHelper databaseHelper)66     TransientRowHelper(Context context, DatabaseHelper databaseHelper) {
67         mContext = context;
68         mDatabaseHelper = databaseHelper;
69     }
70 
71     /**
72      * Ensures that transient rows, inserted previously before current boot, are deleted.
73      */
ensureOldTransientRowsDeleted()74     public void ensureOldTransientRowsDeleted() {
75         synchronized (this) {
76             if (mTransientRowsDeleted) {
77                 return;
78             }
79             mTransientRowsDeleted = true;
80         }
81         if (getLastDeletionBootCount() >= getBootCount()) {
82             // This can be the second execution of TvProvider after boot since system kills
83             // TvProvider in low memory conditions. If this is the case, we shouldn't delete
84             // transient rows.
85             return;
86         }
87         SQLiteDatabase db = mDatabaseHelper.getWritableDatabase();
88         // Delete all the transient programs and channels.
89         db.delete(TvProvider.PREVIEW_PROGRAMS_TABLE, PreviewPrograms.COLUMN_TRANSIENT + "=1", null);
90         db.delete(TvProvider.CHANNELS_TABLE, Channels.COLUMN_TRANSIENT + "=1", null);
91         db.delete(TvProvider.WATCH_NEXT_PROGRAMS_TABLE, WatchNextPrograms.COLUMN_TRANSIENT + "=1",
92                 null);
93         setLastDeletionBootCount();
94     }
95 
96     @VisibleForTesting
getBootCount()97     protected int getBootCount() {
98         return Settings.Global.getInt(mContext.getContentResolver(), Settings.Global.BOOT_COUNT,
99                 -1);
100     }
101 
102     @VisibleForTesting
getLastDeletionBootCount()103     protected int getLastDeletionBootCount() {
104         SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(mContext);
105         return prefs.getInt(PREF_KEY_LAST_DELETION_BOOT_COUNT, -1);
106     }
107 
108     @VisibleForTesting
setLastDeletionBootCount()109     protected void setLastDeletionBootCount() {
110         SharedPreferences.Editor editor = PreferenceManager.getDefaultSharedPreferences(mContext)
111                 .edit();
112         editor.putInt(PREF_KEY_LAST_DELETION_BOOT_COUNT, getBootCount());
113         editor.apply();
114     }
115 }
116