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 backtype.storm.windowing;
  
  import java.util.List;
  
  /**
   * A callback for expiry, activation of events tracked by the {@link WindowManager}
   *
   * @param <T> The type of Event in the window (e.g. Tuple).
   */
  public interface WindowLifecycleListener<T> {
      /**
       * Called on expiry of events from the window due to {@link EvictionPolicy}
       *
       * @param events the expired events
       */
      void onExpiry(List<T> events);
  
      /**
       * Called on activation of the window due to the {@link TriggerPolicy}
       * @param events the list of current events in the window.
       * @param newEvents the newly added events since last activation.
       * @param expired the expired events since last activation.
       */
      void onActivation(List<T> events, List<T> newEvents, List<T> expired);
  }
  