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 org.apache.kafka.streams.processor.internals;
  
  import org.apache.kafka.streams.errors.TaskMigratedException;
  import org.apache.kafka.streams.processor.Cancellable;
  import org.apache.kafka.streams.processor.PunctuationType;
  
  import java.util.PriorityQueue;
  
  public class PunctuationQueue {
  
      private final PriorityQueue<PunctuationSchedule> pq = new PriorityQueue<>();
  
      public Cancellable schedule(final PunctuationSchedule sched) {
          synchronized (pq) {
              pq.add(sched);
          }
          return sched.cancellable();
      }
  
      public void close() {
          synchronized (pq) {
              pq.clear();
          }
      }
  
      /**
       * @throws TaskMigratedException if the task producer got fenced (EOS only)
       */
      boolean maybePunctuate(final long timestamp, final PunctuationType type, final ProcessorNodePunctuator processorNodePunctuator) {
          synchronized (pq) {
              boolean punctuated = false;
              PunctuationSchedule top = pq.peek();
              while (top != null && top.timestamp <= timestamp) {
                  final PunctuationSchedule sched = top;
                  pq.poll();
  
                  if (!sched.isCancelled()) {
                      processorNodePunctuator.punctuate(sched.node(), timestamp, type, sched.punctuator());
                      // sched can be cancelled from within the punctuator
                      if (!sched.isCancelled()) {
                          pq.add(sched.next(timestamp));
                      }
                      punctuated = true;
                  }
  
  
                  top = pq.peek();
              }
  
              return punctuated;
          }
      }
  
      /**
       * Returns true if there is a schedule ready to be punctuated.
       */
      boolean canPunctuate(final long timestamp) {
          synchronized (pq) {
              PunctuationSchedule top = pq.peek();
              while (top != null && top.timestamp <= timestamp) {
                  if (!top.isCancelled()) {
                      return true;
                  }
                  // Side-effect: removes cancelled schedules (not externally visible)
                  pq.poll();
                  top = pq.peek();
              }
              return false;
          }
      }
  
  }
  