content: /*******************************************************************************
   * Copyright 2013 Mario Zechner <badlogicgames@gmail.com>
   * Copyright 2013 Nathan Sweet <nathan.sweet@gmail.com>
   * <p/>
   * Licensed 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
   * <p/>
   * http://www.apache.org/licenses/LICENSE-2.0
   * <p/>
   * 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.oscim.utils.async;
  
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  import java.util.concurrent.RejectedExecutionException;
  import java.util.concurrent.ThreadFactory;
  import java.util.concurrent.TimeUnit;
  
  /**
   * Allows asnynchronous execution of {@link AsyncTask} instances on a separate
   * thread.
   * Needs to be disposed via a call to {@link #dispose()} when no longer used, in
   * which
   * case the executor waits for running tasks to finish. Scheduled but not yet
   * running tasks will not be executed.
   *
   * @author badlogic
   */
  public class AsyncExecutor {
      private final ExecutorService executor;
      private final TaskQueue mainloop;
  
      /**
       * Creates a new AsynchExecutor that allows maxConcurrent {@link Runnable}
       * instances to run in parallel.
       *
       * @param maxConcurrent number of threads.
       */
      public AsyncExecutor(int maxConcurrent, TaskQueue mainloop) {
          this.mainloop = mainloop;
          executor = Executors.newFixedThreadPool(maxConcurrent, new ThreadFactory() {
              @Override
              public Thread newThread(Runnable r) {
                  Thread thread = new Thread(r, "VtmAsyncExecutor");
                  thread.setDaemon(true);
                  thread.setPriority(Thread.NORM_PRIORITY - 1);
                  return thread;
              }
          });
      }
  
      /**
       * Submits a {@link Runnable} to be executed asynchronously. If
       * maxConcurrent runnables are already running, the runnable
       * will be queued.
       *
       * @param task the task to execute asynchronously
       */
      public boolean post(Runnable task) {
          if (task instanceof AsyncTask) {
              ((AsyncTask) task).setTaskQueue(mainloop);
          }
  
          try {
              executor.execute(task);
          } catch (RejectedExecutionException e) {
              return false;
          }
          return true;
      }
  
      /**
       * Waits for running {@link AsyncTask} instances to finish,
       * then destroys any resources like threads. Can not be used
       * after this method is called.
       */
      public void dispose() {
          executor.shutdown();
          try {
              executor.awaitTermination(Long.MAX_VALUE, TimeUnit.SECONDS);
          } catch (InterruptedException e) {
              throw new RuntimeException("Couldn't shutdown loading thread");
          }
      }
  }
  