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;
  
  import backtype.storm.task.TopologyContext;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.List;
  
  /**
   * A {@link WindowAssigner} that windows elements into sliding windows based on the current
   * system time of the machine the operation is running on. Windows can possibly overlap.
   */
  public class SlidingProcessingTimeWindows<T> extends WindowAssigner<T> {
      private static final long serialVersionUID = 1L;
  
      private final long size;
      private final long slide;
  
      private SlidingProcessingTimeWindows(long size, long slide) {
          this.size = size;
          this.slide = slide;
      }
  
      @Override
      public Collection<TimeWindow> assignWindows(T element, long timestamp) {
          timestamp = System.currentTimeMillis();
          List<TimeWindow> windows = new ArrayList<>((int) (size / slide));
          long lastStart = timestamp - timestamp % slide;
          for (long start = lastStart;
               start > timestamp - size;
               start -= slide) {
              windows.add(new TimeWindow(start, start + size));
          }
          return windows;
      }
  
      public long getSize() {
          return size;
      }
  
      public long getSlide() {
          return slide;
      }
  
      @Override
      public Trigger<T> getDefaultTrigger(TopologyContext context) {
          return ProcessingTimeTrigger.create();
      }
  
      @Override
      public String toString() {
          return "SlidingProcessingTimeWindows(" + size + ", " + slide + ")";
      }
  
      /**
       * Creates a new {@code SlidingProcessingTimeWindows} {@link WindowAssigner} that assigns
       * elements to sliding time windows based on the element timestamp.
       *
       * @param size  The size of the generated windows.
       * @param slide The slide interval of the generated windows.
       * @return The time policy.
       */
      public static <T> SlidingProcessingTimeWindows<T> of(long size, long slide) {
          return new SlidingProcessingTimeWindows<>(size, slide);
      }
  }
  