Add support for Apache Derby database

In the current gwtorm implementation, column renames for columns
with a check constraint are not supported by Apache Derby.
To rename a column with a check constraint the column constraint
must be dropped manualy. After that the column can be renamed by
the gwtorm implementation. After the renaming the constraint can
be added again.

Test plan:

* Replace H2 with Apache Derby, add derby to Buck tests rules as
  new dependency and run the tests with `buck test`
* Set up new site with Apache Derby database and perform the tests

Bug: Issue 3441
Change-Id: I46e719ed54ea633c127c7bcd381b882e3a9b37ba

gerrit-pgm/src/main/java/com/google/gerrit/pgm/init/DatabaseConfigModule.java

@@ -31,6 +31,8 @@ public class DatabaseConfigModule extends AbstractModule {
     bind(SitePaths.class).toInstance(site);
     bind(DatabaseConfigInitializer.class).annotatedWith(
         Names.named("db2")).to(DB2Initializer.class);
+    bind(DatabaseConfigInitializer.class).annotatedWith(
+        Names.named("derby")).to(DerbyInitializer.class);
     bind(DatabaseConfigInitializer.class).annotatedWith(
         Names.named("h2")).to(H2Initializer.class);
     bind(DatabaseConfigInitializer.class).annotatedWith(

gerrit-pgm/src/main/java/com/google/gerrit/pgm/init/DerbyInitializer.java

@@ -0,0 +1,51 @@
+// Copyright (C) 2015 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.gerrit.pgm.init;
+
+import static com.google.gerrit.pgm.init.api.InitUtil.die;
+
+import com.google.gerrit.common.FileUtil;
+import com.google.gerrit.pgm.init.api.Section;
+import com.google.gerrit.server.config.SitePaths;
+import com.google.inject.Inject;
+
+import java.nio.file.Path;
+
+class DerbyInitializer implements DatabaseConfigInitializer {
+
+  private final SitePaths site;
+
+  @Inject
+  DerbyInitializer(final SitePaths site) {
+    this.site = site;
+  }
+
+  @Override
+  public void initConfig(Section databaseSection) {
+    String path = databaseSection.get("database");
+    Path db;
+    if (path == null) {
+      db = site.resolve("db").resolve("ReviewDB");
+      databaseSection.set("database", db.toString());
+    } else {
+      db = site.resolve(path);
+    }
+    if (db == null) {
+      throw die("database.database must be supplied for Derby");
+    }
+    db = db.getParent();
+    FileUtil.mkdirsOrDie(db, "cannot create database.database");
+  }
+}

gerrit-pgm/src/main/java/com/google/gerrit/pgm/init/JDBCInitializer.java

@@ -33,7 +33,9 @@ class JDBCInitializer implements DatabaseConfigInitializer {
   private void guessDriver(Section database) {
     String url = Strings.emptyToNull(database.get("url"));
     if (url != null && Strings.isNullOrEmpty(database.get("driver"))) {
-      if (url.startsWith("jdbc:h2:")) {
+      if (url.startsWith("jdbc:derby:")) {
+        database.set("driver", "org.apache.derby.jdbc.EmbeddedDriver");
+      } else if (url.startsWith("jdbc:h2:")) {
         database.set("driver", "org.h2.Driver");
       } else if (url.startsWith("jdbc:mysql:")) {
         database.set("driver", "com.mysql.jdbc.Driver");