Split out shared database components for reuse in caching

PiperOrigin-RevId: 229946997

library/core/src/main/java/com/google/android/exoplayer2/database/DatabaseProvider.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.database;
+
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteException;
+
+/**
+ * Provides {@link SQLiteDatabase} instances to ExoPlayer components, which may read and write
+ * tables prefixed with {@link #TABLE_PREFIX}.
+ */
+public interface DatabaseProvider {
+
+  /** Prefix for tables that can be read and written by ExoPlayer components. */
+  String TABLE_PREFIX = "ExoPlayer";
+
+  /**
+   * Creates and/or opens a database that will be used for reading and writing.
+   *
+   * <p>Once opened successfully, the database is cached, so you can call this method every time you
+   * need to write to the database. Errors such as bad permissions or a full disk may cause this
+   * method to fail, but future attempts may succeed if the problem is fixed.
+   *
+   * @throws SQLiteException If the database cannot be opened for writing.
+   * @return A read/write database object.
+   */
+  SQLiteDatabase getWritableDatabase();
+
+  /**
+   * Creates and/or opens a database. This will be the same object returned by {@link
+   * #getWritableDatabase()} unless some problem, such as a full disk, requires the database to be
+   * opened read-only. In that case, a read-only database object will be returned. If the problem is
+   * fixed, a future call to {@link #getWritableDatabase()} may succeed, in which case the read-only
+   * database object will be closed and the read/write object will be returned in the future.
+   *
+   * <p>Once opened successfully, the database is cached, so you can call this method every time you
+   * need to read from the database.
+   *
+   * @throws SQLiteException If the database cannot be opened.
+   * @return A database object valid until {@link #getWritableDatabase()} is called.
+   */
+  SQLiteDatabase getReadableDatabase();
+}

library/core/src/main/java/com/google/android/exoplayer2/database/DefaultDatabaseProvider.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.database;
+
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteOpenHelper;
+
+/** A {@link DatabaseProvider} that provides instances obtained from a {@link SQLiteOpenHelper}. */
+public final class DefaultDatabaseProvider implements DatabaseProvider {
+
+  private final SQLiteOpenHelper sqliteOpenHelper;
+
+  /**
+   * @param sqliteOpenHelper An {@link SQLiteOpenHelper} from which to obtain database instances.
+   */
+  public DefaultDatabaseProvider(SQLiteOpenHelper sqliteOpenHelper) {
+    this.sqliteOpenHelper = sqliteOpenHelper;
+  }
+
+  @Override
+  public SQLiteDatabase getWritableDatabase() {
+    return sqliteOpenHelper.getWritableDatabase();
+  }
+
+  @Override
+  public SQLiteDatabase getReadableDatabase() {
+    return sqliteOpenHelper.getReadableDatabase();
+  }
+}

library/core/src/main/java/com/google/android/exoplayer2/database/ExoDatabaseProvider.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.database;
+
+import android.content.Context;
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteOpenHelper;
+
+/**
+ * An {@link SQLiteOpenHelper} that provides instances of a standalone ExoPlayer database.
+ *
+ * <p>Suitable for use by applications that do not already have their own database, or which would
+ * prefer to keep ExoPlayer tables isolated in their own database. Other applications should prefer
+ * to use {@link DefaultDatabaseProvider} with their own {@link SQLiteOpenHelper}.
+ */
+public final class ExoDatabaseProvider extends SQLiteOpenHelper implements DatabaseProvider {
+
+  /** The file name used for the standalone ExoPlayer database. */
+  public static final String DATABASE_NAME = "exoplayer_internal.db";
+
+  private static final int VERSION = 1;
+
+  public ExoDatabaseProvider(Context context) {
+    super(context.getApplicationContext(), DATABASE_NAME, /* factory= */ null, VERSION);
+  }
+
+  @Override
+  public void onCreate(SQLiteDatabase db) {
+    // Features create their own tables.
+  }
+
+  @Override
+  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+    // Features handle their own upgrades.
+  }
+
+  @Override
+  public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+    // TODO: Wipe the database.
+    super.onDowngrade(db, oldVersion, newVersion);
+  }
+}

library/core/src/main/java/com/google/android/exoplayer2/database/VersionTable.java

@@ -0,0 +1,116 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.database;
+
+import android.content.ContentValues;
+import android.database.Cursor;
+import android.database.DatabaseUtils;
+import android.database.sqlite.SQLiteDatabase;
+import android.support.annotation.IntDef;
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * A table that holds version information about other ExoPlayer tables. This allows ExoPlayer tables
+ * to be versioned independently to the version of the containing database.
+ */
+public final class VersionTable {
+
+  /** Returned by {@link #getVersion(int)} if the version is unset. */
+  public static final int VERSION_UNSET = -1;
+  /** Version of tables used for offline functionality. */
+  public static final int FEATURE_OFFLINE = 0;
+  /** Version of tables used for cache functionality. */
+  public static final int FEATURE_CACHE = 1;
+
+  private static final String TABLE_NAME = DatabaseProvider.TABLE_PREFIX + "Versions";
+
+  private static final String COLUMN_FEATURE = "feature";
+  private static final String COLUMN_VERSION = "version";
+
+  private static final String SQL_CREATE_TABLE_IF_NOT_EXISTS =
+      "CREATE TABLE IF NOT EXISTS "
+          + TABLE_NAME
+          + " ("
+          + COLUMN_FEATURE
+          + " INTEGER PRIMARY KEY NOT NULL,"
+          + COLUMN_VERSION
+          + " INTEGER NOT NULL)";
+
+  @Documented
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({FEATURE_OFFLINE, FEATURE_CACHE})
+  private @interface Feature {}
+
+  private final DatabaseProvider databaseProvider;
+
+  public VersionTable(DatabaseProvider databaseProvider) {
+    this.databaseProvider = databaseProvider;
+    // Check whether the table exists to avoid getting a writable database if we don't need one.
+    if (!doesTableExist(databaseProvider, TABLE_NAME)) {
+      databaseProvider.getWritableDatabase().execSQL(SQL_CREATE_TABLE_IF_NOT_EXISTS);
+    }
+  }
+
+  /**
+   * Sets the version of tables belonging to the specified feature.
+   *
+   * @param feature The feature.
+   * @param version The version.
+   */
+  public void setVersion(@Feature int feature, int version) {
+    ContentValues values = new ContentValues();
+    values.put(COLUMN_FEATURE, feature);
+    values.put(COLUMN_VERSION, version);
+    SQLiteDatabase writableDatabase = databaseProvider.getWritableDatabase();
+    writableDatabase.replace(TABLE_NAME, /* nullColumnHack= */ null, values);
+  }
+
+  /**
+   * Returns the version of tables belonging to the specified feature, or {@link #VERSION_UNSET} if
+   * no version information is available.
+   */
+  public int getVersion(@Feature int feature) {
+    String selection = COLUMN_FEATURE + " = ?";
+    String[] selectionArgs = {Integer.toString(feature)};
+    try (Cursor cursor =
+        databaseProvider
+            .getReadableDatabase()
+            .query(
+                TABLE_NAME,
+                new String[] {COLUMN_VERSION},
+                selection,
+                selectionArgs,
+                /* groupBy= */ null,
+                /* having= */ null,
+                /* orderBy= */ null)) {
+      if (cursor.getCount() == 0) {
+        return VERSION_UNSET;
+      }
+      cursor.moveToNext();
+      return cursor.getInt(/* COLUMN_VERSION index */ 0);
+    }
+  }
+
+  /* package */ static boolean doesTableExist(DatabaseProvider databaseProvider, String tableName) {
+    SQLiteDatabase readableDatabase = databaseProvider.getReadableDatabase();
+    long count =
+        DatabaseUtils.queryNumEntries(
+            readableDatabase, "sqlite_master", "tbl_name = ?", new String[] {tableName});
+    return count > 0;
+  }
+}