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 WARRANTIESOR 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.aries.blueprint.utils.threading.impl;
  
  import java.util.Queue;
  import java.util.concurrent.LinkedBlockingQueue;
  import java.util.concurrent.atomic.AtomicReference;
  
  public class DiscardableRunnable implements Runnable, Discardable<Runnable> {
      private AtomicReference<Runnable> r = new AtomicReference<Runnable>();
      private Queue<Discardable<Runnable>> _removeFromListOnRun;
  
      public DiscardableRunnable(Runnable run, Queue<Discardable<Runnable>> _unprocessedWork) {
          r.set(run);
          _removeFromListOnRun = _unprocessedWork;
          _removeFromListOnRun.add(this);
      }
  
      private DiscardableRunnable(Runnable run) {
          r.set(run);
          _removeFromListOnRun = new LinkedBlockingQueue<Discardable<Runnable>>();
      }
  
      public void run() {
          _removeFromListOnRun.remove(this);
          Runnable run = r.get();
          if (run != null) {
              run.run();
          }
      }
  
      public Runnable discard() {
          _removeFromListOnRun.remove(this);
          return new DiscardableRunnable(r.getAndSet(null));
      }
  }