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 com.alibaba.jstorm.window;
  
  public class EventTimeTrigger<T> extends Trigger<T> {
      private static final long serialVersionUID = 1L;
  
      private EventTimeTrigger() {
      }
  
      /**
       * If a watermark arrives, we need to check all pending windows.
       * If any of the pending window suffices, we should fire immediately by registering a timer without delay.
       * Otherwise we register a timer whose time is the window end plus max lag time
       */
      @Override
      public TriggerResult onElement(Object element, long timestamp, TimeWindow window, TriggerContext ctx) {
          ctx.registerEventTimeTimer(window.getEnd() + ctx.getMaxLagMs(), window);
          return TriggerResult.CONTINUE;
      }
  
      @Override
      public String toString() {
          return "EventTimeTrigger()";
      }
  
      /**
       * Creates an event-time trigger that fires once the watermark passes the end of the window.
       *
       * <p>
       * Once the trigger fires all elements are discarded. Elements that arrive late immediately
       * trigger window evaluation with just this one element.
       */
      public static <T> EventTimeTrigger<T> create() {
          return new EventTimeTrigger<>();
      }
  
  }
  