content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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 org.apache.ambari.server.controller.utilities;
  
  import org.apache.ambari.server.controller.internal.ClusterControllerImpl;
  import org.apache.ambari.server.controller.spi.ClusterController;
  import org.apache.ambari.server.controller.spi.ProviderModule;
  import org.apache.ambari.server.view.ViewProviderModule;
  
  /**
   * Temporary class to bootstrap a cluster controller.  TODO : Replace this global state with injection.
   */
  public class ClusterControllerHelper {
  
    private static String PROVIDER_MODULE_CLASS = System.getProperty("provider.module.class",
        "org.apache.ambari.server.controller.internal.DefaultProviderModule");
  
    private static ClusterController controller;
  
    public static synchronized ClusterController getClusterController() {
      if (controller == null) {
        try {
          Class<?> implClass = Class.forName(PROVIDER_MODULE_CLASS);
          ProviderModule providerModule = ViewProviderModule.getViewProviderModule((ProviderModule) implClass.newInstance());
          controller = new ClusterControllerImpl(providerModule);
  
        } catch (Exception e) {
          throw new IllegalStateException("Can't create provider module " + PROVIDER_MODULE_CLASS, e);
        }
      }
      return controller;
    }
  }
  