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.coordinator.common.runtime;
  
  import java.util.Deque;
  import java.util.LinkedList;
  import java.util.concurrent.RejectedExecutionException;
  
  /**
   * A CoordinatorEventProcessor that queues events and execute the next one
   * when poll() is called.
   */
  public class ManualEventProcessor implements CoordinatorEventProcessor {
      private final Deque<CoordinatorEvent> queue = new LinkedList<>();
  
      @Override
      public void enqueueLast(CoordinatorEvent event) throws RejectedExecutionException {
          queue.addLast(event);
      }
  
      @Override
      public void enqueueFirst(CoordinatorEvent event) throws RejectedExecutionException {
          queue.addFirst(event);
      }
  
      public boolean poll() {
          CoordinatorEvent event = queue.poll();
          if (event == null) return false;
  
          try {
              event.run();
          } catch (Throwable ex) {
              event.complete(ex);
          }
  
          return true;
      }
  
      public int size() {
          return queue.size();
      }
  
      @Override
      public void close() {}
  }
  