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.concurrent.atomic.AtomicInteger;
  
  /**
   * A trigger that tracks event counts and calls back {@link TriggerHandler#onTrigger()}
   * when the count threshold is hit.
   *
   * @param <T> the type of event tracked by this policy.
   */
  public class CountTriggerPolicy<T> implements TriggerPolicy<T> {
      private final int count;
      private final AtomicInteger currentCount;
      private final TriggerHandler handler;
      private final EvictionPolicy<T> evictionPolicy;
      private boolean started;
  
      public CountTriggerPolicy(int count, TriggerHandler handler, EvictionPolicy<T> evictionPolicy) {
          this.count = count;
          this.currentCount = new AtomicInteger();
          this.handler = handler;
          this.evictionPolicy = evictionPolicy;
          this.started = false;
      }
  
      @Override
      public void track(Event<T> event) {
          if (started && !event.isWatermark()) {
              if (currentCount.incrementAndGet() >= count) {
                  evictionPolicy.setContext(System.currentTimeMillis());
                  handler.onTrigger();
              }
          }
      }
  
      @Override
      public void reset() {
          currentCount.set(0);
      }
  
      @Override
      public void start() {
          started = true;
      }
  
      @Override
      public void shutdown() {
          // NOOP
      }
  
      @Override
      public String toString() {
          return "CountTriggerPolicy{" +
                  "count=" + count +
                  ", currentCount=" + currentCount +
                  ", started=" + started +
                  '}';
      }
  }
  