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
   * <p>
   * http://www.apache.org/licenses/LICENSE-2.0
   * <p>
   * 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 storm.trident.windowing;
  
  import java.util.List;
  
  import storm.trident.operation.TridentCollector;
  
  /**
   * InMemoryWindowsStoreFactory contains a single instance of {@link InMemoryWindowsStore} which will be used for
   * storing tuples and triggers of the window. The same InMemoryWindowsStoreFactory instance is passed to {@link WindowsStateUpdater},
   * which removes successfully emitted triggers from the same {@code inMemoryWindowsStore} instance in
   * {@link WindowsStateUpdater#updateState(WindowsState, List, TridentCollector)}.
   */
  public class InMemoryWindowsStoreFactory implements WindowsStoreFactory {
  
      private InMemoryWindowsStore inMemoryWindowsStore;
  
      @Override
      public WindowsStore create() {
          if (inMemoryWindowsStore == null) {
              inMemoryWindowsStore = new InMemoryWindowsStore();
          }
          return inMemoryWindowsStore;
      }
  }
  