Add device config database

Includes a DataStore, DbAdapter, DbHelper and DeviceConfigService

Test: follow-up

Bug: 263955152
Change-Id: I89ceaa0692043a424b5e76844725a49fd3bb6a0e

1 files changed, 84 insertions, 0 deletions

diff --git a/service/java/com/android/server/deviceconfig/db/DeviceConfigDbHelper.java b/service/java/com/android/server/deviceconfig/db/DeviceConfigDbHelper.java
new file mode 100644
index 0000000..d7c90cc
--- /dev/null
+++ b/service/java/com/android/server/deviceconfig/db/DeviceConfigDbHelper.java
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2023 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.android.server.deviceconfig.db;
+
+import android.content.Context;
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteOpenHelper;
+import android.provider.BaseColumns;
+
+/**
+ * @hide
+ */
+public class DeviceConfigDbHelper extends SQLiteOpenHelper {
+    public static final int DATABASE_VERSION = 1;
+    public static final String DATABASE_NAME = "config_infrastructure.db";
+
+    /**
+     * TODO(b/265948914) / to consider:
+     *
+     * - enforce uniqueness of (namespace, key) pairs
+     * - synchronize calls that modify the db (maybe reads too?)
+     * - probably use a read/write lock
+     * - per-process caching of results so we don't go to the db every time
+     * - test the sql commands to make sure they work well (e.g. where clauses are
+     * written properly)
+     * - check the performance of the sql commands and look for optimizations
+     * - write a test for adapter.setProperties that has some but not all
+     * preexisting properties
+     * - Settings.Config has a concept "makeDefault" which is not implemented here
+     * - ensure that any sql exceptions are not thrown to the callers (where methods
+     * can return
+     * false)
+     * - see what happens if a caller starts observing changes before the database
+     * is loaded/ready (early in the boot process)
+     * - I've seen strict mode alerts about doing I/O in the main thread after a
+     * device boots. Maybe we can't avoid it but double check.
+     * - finish API implementation in DatabaseDataStore
+     */
+
+    interface Contract {
+        class DeviceConfigEntry implements BaseColumns {
+            public static final String TABLE_NAME = "config";
+            public static final String COLUMN_NAME_NAMESPACE = "namespace";
+            public static final String COLUMN_NAME_KEY = "config_key";
+            public static final String COLUMN_NAME_VALUE = "config_value";
+        }
+    }
+
+    private static final String SQL_CREATE_ENTRIES =
+            "CREATE TABLE " + Contract.DeviceConfigEntry.TABLE_NAME + " (" +
+                    Contract.DeviceConfigEntry._ID + " INTEGER PRIMARY KEY," +
+                    Contract.DeviceConfigEntry.COLUMN_NAME_NAMESPACE + " TEXT," +
+                    Contract.DeviceConfigEntry.COLUMN_NAME_KEY + " TEXT," +
+                    Contract.DeviceConfigEntry.COLUMN_NAME_VALUE + " TEXT)";
+
+    public DeviceConfigDbHelper(Context context) {
+        super(context, DATABASE_NAME, null, DATABASE_VERSION);
+    }
+
+    @Override
+    public void onCreate(SQLiteDatabase db) {
+        db.execSQL(SQL_CREATE_ENTRIES);
+    }
+
+    @Override
+    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+        // no op for now
+    }
+
+}