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
17package android.database.sqlite;
18
19import android.app.ActivityThread;
20import android.app.Application;
21import android.provider.Settings;
22import android.text.TextUtils;
23import android.util.KeyValueListParser;
24import android.util.Log;
25
26import com.android.internal.annotations.VisibleForTesting;
27
28/**
29 * Helper class for accessing
30 * {@link Settings.Global#SQLITE_COMPATIBILITY_WAL_FLAGS global compatibility WAL settings}.
31 *
32 * <p>The value of {@link Settings.Global#SQLITE_COMPATIBILITY_WAL_FLAGS} is cached on first access
33 * for consistent behavior across all connections opened in the process.
34 * @hide
35 */
36public class SQLiteCompatibilityWalFlags {
37
38    private static final String TAG = "SQLiteCompatibilityWalFlags";
39
40    private static volatile boolean sInitialized;
41    private static volatile boolean sFlagsSet;
42    private static volatile boolean sCompatibilityWalSupported;
43    private static volatile String sWALSyncMode;
44    // This flag is used to avoid recursive initialization due to circular dependency on Settings
45    private static volatile boolean sCallingGlobalSettings;
46
47    /**
48     * @hide
49     */
50    @VisibleForTesting
51    public static boolean areFlagsSet() {
52        initIfNeeded();
53        return sFlagsSet;
54    }
55
56    /**
57     * @hide
58     */
59    @VisibleForTesting
60    public static boolean isCompatibilityWalSupported() {
61        initIfNeeded();
62        return sCompatibilityWalSupported;
63    }
64
65    /**
66     * @hide
67     */
68    @VisibleForTesting
69    public static String getWALSyncMode() {
70        initIfNeeded();
71        return sWALSyncMode;
72    }
73
74    private static void initIfNeeded() {
75        if (sInitialized || sCallingGlobalSettings) {
76            return;
77        }
78        ActivityThread activityThread = ActivityThread.currentActivityThread();
79        Application app = activityThread == null ? null : activityThread.getApplication();
80        String flags = null;
81        if (app == null) {
82            Log.w(TAG, "Cannot read global setting "
83                    + Settings.Global.SQLITE_COMPATIBILITY_WAL_FLAGS + " - "
84                    + "Application state not available");
85        } else {
86            try {
87                sCallingGlobalSettings = true;
88                flags = Settings.Global.getString(app.getContentResolver(),
89                        Settings.Global.SQLITE_COMPATIBILITY_WAL_FLAGS);
90            } finally {
91                sCallingGlobalSettings = false;
92            }
93        }
94
95        init(flags);
96    }
97
98    /**
99     * @hide
100     */
101    @VisibleForTesting
102    public static void init(String flags) {
103        if (TextUtils.isEmpty(flags)) {
104            sInitialized = true;
105            return;
106        }
107        KeyValueListParser parser = new KeyValueListParser(',');
108        try {
109            parser.setString(flags);
110        } catch (IllegalArgumentException e) {
111            Log.e(TAG, "Setting has invalid format: " + flags, e);
112            sInitialized = true;
113            return;
114        }
115        sCompatibilityWalSupported = parser.getBoolean("compatibility_wal_supported",
116                SQLiteGlobal.isCompatibilityWalSupported());
117        sWALSyncMode = parser.getString("wal_syncmode", SQLiteGlobal.getWALSyncMode());
118        Log.i(TAG, "Read compatibility WAL flags: compatibility_wal_supported="
119                + sCompatibilityWalSupported + ", wal_syncmode=" + sWALSyncMode);
120        sFlagsSet = true;
121        sInitialized = true;
122    }
123
124    /**
125     * @hide
126     */
127    @VisibleForTesting
128    public static void reset() {
129        sInitialized = false;
130        sFlagsSet = false;
131        sCompatibilityWalSupported = false;
132        sWALSyncMode = null;
133    }
134}
135