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 androidx.room;
18
19import android.database.Cursor;
20
21import androidx.annotation.NonNull;
22import androidx.annotation.Nullable;
23import androidx.annotation.RestrictTo;
24import androidx.room.migration.Migration;
25import androidx.sqlite.db.SimpleSQLiteQuery;
26import androidx.sqlite.db.SupportSQLiteDatabase;
27import androidx.sqlite.db.SupportSQLiteOpenHelper;
28
29import java.util.List;
30
31/**
32 * An open helper that holds a reference to the configuration until the database is opened.
33 *
34 * @hide
35 */
36@SuppressWarnings("unused")
37@RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
38public class RoomOpenHelper extends SupportSQLiteOpenHelper.Callback {
39    @Nullable
40    private DatabaseConfiguration mConfiguration;
41    @NonNull
42    private final Delegate mDelegate;
43    @NonNull
44    private final String mIdentityHash;
45    /**
46     * Room v1 had a bug where the hash was not consistent if fields are reordered.
47     * The new has fixes it but we still need to accept the legacy hash.
48     */
49    @NonNull // b/64290754
50    private final String mLegacyHash;
51
52    public RoomOpenHelper(@NonNull DatabaseConfiguration configuration, @NonNull Delegate delegate,
53            @NonNull String identityHash, @NonNull String legacyHash) {
54        super(delegate.version);
55        mConfiguration = configuration;
56        mDelegate = delegate;
57        mIdentityHash = identityHash;
58        mLegacyHash = legacyHash;
59    }
60
61    public RoomOpenHelper(@NonNull DatabaseConfiguration configuration, @NonNull Delegate delegate,
62            @NonNull String legacyHash) {
63        this(configuration, delegate, null, legacyHash);
64    }
65
66    @Override
67    public void onConfigure(SupportSQLiteDatabase db) {
68        super.onConfigure(db);
69    }
70
71    @Override
72    public void onCreate(SupportSQLiteDatabase db) {
73        updateIdentity(db);
74        mDelegate.createAllTables(db);
75        mDelegate.onCreate(db);
76    }
77
78    @Override
79    public void onUpgrade(SupportSQLiteDatabase db, int oldVersion, int newVersion) {
80        boolean migrated = false;
81        if (mConfiguration != null) {
82            List<Migration> migrations = mConfiguration.migrationContainer.findMigrationPath(
83                    oldVersion, newVersion);
84            if (migrations != null) {
85                for (Migration migration : migrations) {
86                    migration.migrate(db);
87                }
88                mDelegate.validateMigration(db);
89                updateIdentity(db);
90                migrated = true;
91            }
92        }
93        if (!migrated) {
94            if (mConfiguration != null && !mConfiguration.isMigrationRequiredFrom(oldVersion)) {
95                mDelegate.dropAllTables(db);
96                mDelegate.createAllTables(db);
97            } else {
98                throw new IllegalStateException("A migration from " + oldVersion + " to "
99                        + newVersion + " was required but not found. Please provide the "
100                        + "necessary Migration path via "
101                        + "RoomDatabase.Builder.addMigration(Migration ...) or allow for "
102                        + "destructive migrations via one of the "
103                        + "RoomDatabase.Builder.fallbackToDestructiveMigration* methods.");
104            }
105        }
106    }
107
108    @Override
109    public void onDowngrade(SupportSQLiteDatabase db, int oldVersion, int newVersion) {
110        onUpgrade(db, oldVersion, newVersion);
111    }
112
113    @Override
114    public void onOpen(SupportSQLiteDatabase db) {
115        super.onOpen(db);
116        checkIdentity(db);
117        mDelegate.onOpen(db);
118        // there might be too many configurations etc, just clear it.
119        mConfiguration = null;
120    }
121
122    private void checkIdentity(SupportSQLiteDatabase db) {
123        String identityHash = null;
124        if (hasRoomMasterTable(db)) {
125            Cursor cursor = db.query(new SimpleSQLiteQuery(RoomMasterTable.READ_QUERY));
126            //noinspection TryFinallyCanBeTryWithResources
127            try {
128                if (cursor.moveToFirst()) {
129                    identityHash = cursor.getString(0);
130                }
131            } finally {
132                cursor.close();
133            }
134        }
135        if (!mIdentityHash.equals(identityHash) && !mLegacyHash.equals(identityHash)) {
136            throw new IllegalStateException("Room cannot verify the data integrity. Looks like"
137                    + " you've changed schema but forgot to update the version number. You can"
138                    + " simply fix this by increasing the version number.");
139        }
140    }
141
142    private void updateIdentity(SupportSQLiteDatabase db) {
143        createMasterTableIfNotExists(db);
144        db.execSQL(RoomMasterTable.createInsertQuery(mIdentityHash));
145    }
146
147    private void createMasterTableIfNotExists(SupportSQLiteDatabase db) {
148        db.execSQL(RoomMasterTable.CREATE_QUERY);
149    }
150
151    private static boolean hasRoomMasterTable(SupportSQLiteDatabase db) {
152        Cursor cursor = db.query("SELECT 1 FROM sqlite_master WHERE type = 'table' AND name='"
153                + RoomMasterTable.TABLE_NAME + "'");
154        //noinspection TryFinallyCanBeTryWithResources
155        try {
156            return cursor.moveToFirst() && cursor.getInt(0) != 0;
157        } finally {
158            cursor.close();
159        }
160    }
161
162    /**
163     * @hide
164     */
165    @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
166    public abstract static class Delegate {
167        public final int version;
168
169        public Delegate(int version) {
170            this.version = version;
171        }
172
173        protected abstract void dropAllTables(SupportSQLiteDatabase database);
174
175        protected abstract void createAllTables(SupportSQLiteDatabase database);
176
177        protected abstract void onOpen(SupportSQLiteDatabase database);
178
179        protected abstract void onCreate(SupportSQLiteDatabase database);
180
181        /**
182         * Called after a migration run to validate database integrity.
183         *
184         * @param db The SQLite database.
185         */
186        protected abstract void validateMigration(SupportSQLiteDatabase db);
187    }
188
189}
190