content: /*
   * Copyright 1999-2023 Alibaba Group Holding Ltd.
   *
   * 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.alibaba.nacos.persistence.datasource;
  
  import com.alibaba.nacos.persistence.configuration.DatasourceConfiguration;
  
  /**
   * Datasource adapter.
   *
   * @author Nacos
   */
  public class DynamicDataSource {
      
      private DataSourceService localDataSourceService = null;
      
      private DataSourceService basicDataSourceService = null;
      
      private static final DynamicDataSource INSTANCE = new DynamicDataSource();
  
      private DynamicDataSource() {}
  
      public static DynamicDataSource getInstance() {
          return INSTANCE;
      }
      
      public synchronized DataSourceService getDataSource() {
          try {
              
              // Embedded storage is used by default in stand-alone mode
              // In cluster mode, external databases are used by default
              
              if (DatasourceConfiguration.isEmbeddedStorage()) {
                  if (localDataSourceService == null) {
                      localDataSourceService = new LocalDataSourceServiceImpl();
                      localDataSourceService.init();
                  }
                  return localDataSourceService;
              } else {
                  if (basicDataSourceService == null) {
                      basicDataSourceService = new ExternalDataSourceServiceImpl();
                      basicDataSourceService.init();
                  }
                  return basicDataSourceService;
              }
          } catch (Exception e) {
              throw new RuntimeException(e);
          }
      }
      
  }
  