TaskQueue.java

/* http://google-ukdev.blogspot.com/2009/01/crimes-against-code-and-using-threads.html
 * Some modification made by barclay to be consistent with formatting.
 */

package net.redgeek.android.eventrend.util;

import java.util.LinkedList;

import android.util.Log;

public class TaskQueue {
  private static final String TAG = "TaskQueue";

  private LinkedList<Runnable> mTasks;
  private Thread mThread;
  private boolean mRunning;
  private Runnable mInternalRunnable;

  private class InternalRunnable implements Runnable {
    public void run() {
      internalRun();
    }
  }

  public TaskQueue() {
    mTasks = new LinkedList<Runnable>();
    mInternalRunnable = new InternalRunnable();
  }

  public void start() {
    if (!mRunning) {
      mThread = new Thread(mInternalRunnable);
      mThread.setDaemon(true);
      mRunning = true;
      mThread.start();
    }
  }

  public void stop() {
    mRunning = false;
  }

  public void addTask(Runnable task) {
    synchronized (mTasks) {
      mTasks.addFirst(task);
      mTasks.notify(); // notify any waiting threads
    }
  }

  private Runnable getNextTask() {
    synchronized (mTasks) {
      while (mTasks.isEmpty()) {
        try {
          mTasks.wait();
        } catch (InterruptedException e) {
          Log.e(TAG, "Task interrupted", e);
          stop();
        }
      }
      return mTasks.removeLast();
    }
  }

  private void internalRun() {
    while (mRunning) {
      Runnable task = getNextTask();
      try {
        task.run();
      } catch (Throwable t) {
        Log.e(TAG, "Task threw an exception", t);
      }
    }
  }
}