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.utils;
  
  import java.util.concurrent.ConcurrentLinkedQueue;
  
  public class ThreadResourceManager<T> {
      public interface ResourceFactory<X> {
          X makeResource();
      }
  
      ResourceFactory<T> _factory;
      ConcurrentLinkedQueue<T> _resources = new ConcurrentLinkedQueue<>();
  
      public ThreadResourceManager(ResourceFactory<T> factory) {
          _factory = factory;
      }
  
      public T acquire() {
          T ret = _resources.poll();
          if (ret == null) {
              ret = _factory.makeResource();
          }
          return ret;
      }
  
      public void release(T resource) {
          _resources.add(resource);
      }
  }
  