package org.asteriskjava.fastagi;
   
   import org.asteriskjava.util.DaemonThreadFactory;
   import org.asteriskjava.util.Log;
   import org.asteriskjava.util.LogFactory;
   import org.asteriskjava.fastagi.internal.AgiChannelFactory;
   import org.asteriskjava.fastagi.internal.DefaultAgiChannelFactory;
   
   import java.util.concurrent.RejectedExecutionException;
  import java.util.concurrent.ThreadPoolExecutor;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.SynchronousQueue;
  
  /**
   * Abstract base class for FastAGI and AsyncAGI servers.
   *
   * @since 1.0.0
   */
  public abstract class AbstractAgiServer
  {
      private final Log logger = LogFactory.getLog(getClass());
  
      /**
       * The default thread pool size.
       */
      private static final int DEFAULT_POOL_SIZE = 10;
  
      /**
       * The default thread pool size.
       */
      private static final int DEFAULT_MAXIMUM_POOL_SIZE = 100;
  
      /**
       * The minimum number of worker threads in the thread pool.
       */
      private int poolSize = DEFAULT_POOL_SIZE;
  
      /**
       * The maximum number of worker threads in the thread pool. This equals the maximum number of
       * concurrent requests this AgiServer can serve.
       */
      private int maximumPoolSize = DEFAULT_MAXIMUM_POOL_SIZE;
  
      /**
       * The thread pool that contains the worker threads to process incoming requests.
       */
      private ThreadPoolExecutor pool;
  
      /**
       * The strategy to use for mapping AgiRequests to AgiScripts that serve them.
       */
      private MappingStrategy mappingStrategy;
  
      /**
       * The factory to use for creating new AgiChannel instances.
       */
      private final AgiChannelFactory agiChannelFactory;
  
      private volatile boolean die = false;
  
      public AbstractAgiServer()
      {
          this(new DefaultAgiChannelFactory());
      }
  
      /**
       * Creates a new AbstractAgiServer with the given channel factory.
       *
       * @param agiChannelFactory the AgiChannelFactory to use for creating new AgiChannel instances.
       * @since 1.0.0
       */
      public AbstractAgiServer(AgiChannelFactory agiChannelFactory)
      {
          if (agiChannelFactory == null)
          {
              throw new IllegalArgumentException("AgiChannelFactory must not be null");
          }
  
          logger.debug("Using channelFactory " + agiChannelFactory.getClass().getCanonicalName());
          this.agiChannelFactory = agiChannelFactory;
      }
  
      /**
       * Returns the AgiChannelFactory to use for creating new AgiChannel instances.
       *
       * @return the AgiChannelFactory to use for creating new AgiChannel instances.
       */
      protected AgiChannelFactory getAgiChannelFactory()
      {
          return this.agiChannelFactory;
      }
  
      /**
       * Returns the default number of worker threads in the thread pool.
       *
       * @return the default number of worker threads in the thread pool.
       * @since 1.0.0
       */
      public int getPoolSize()
     {
         return poolSize;
     }
 
     /**
      * Sets the default number of worker threads in the thread pool.
      * <p/>
      * This is the number of threads that are available even if they are idle.
      * <p/>
      * The default pool size is 10.
      *
      * @param poolSize the size of the worker thread pool.
      * @throws IllegalArgumentException if the new pool size is negative
      * @see {@link java.util.concurrent.ThreadPoolExecutor#setCorePoolSize(int)}
      */
     public synchronized void setPoolSize(int poolSize)
     {
         if (poolSize < 0)
         {
             throw new IllegalArgumentException("New poolSize (" + poolSize + ") is must not be negative");
         }
 
         if (pool != null)
         {
             pool.setCorePoolSize(poolSize);
         }
         this.poolSize = poolSize;
     }
 
     /**
      * Returns the maximum number of worker threads in the thread pool.
      *
      * @return the maximum number of worker threads in the thread pool.
      * @since 1.0.0
      */
     public int getMaximumPoolSize()
     {
         return maximumPoolSize;
     }
 
     /**
      * Sets the maximum number of worker threads in the thread pool.
      * <p/>
      * This equals the maximum number of concurrent requests this AgiServer can serve.
      * <p/>
      * The default maximum pool size is 100.
      *
      * @param maximumPoolSize the maximum size of the worker thread pool.
      * @throws IllegalArgumentException if maximumPoolSize is less than current pool size or less than or equal to 0.
      * @see {@link java.util.concurrent.ThreadPoolExecutor#setMaximumPoolSize(int)}
      */
     public synchronized void setMaximumPoolSize(int maximumPoolSize)
     {
         if (maximumPoolSize <= 0)
         {
             throw new IllegalArgumentException("New maximumPoolSize (" + maximumPoolSize + ") is must be positive");
         }
 
         if (maximumPoolSize < poolSize)
         {
             throw new IllegalArgumentException("New maximumPoolSize (" + maximumPoolSize + ") is less than current pool size (" + poolSize + ")");
         }
 
         if (pool != null)
         {
             pool.setMaximumPoolSize(maximumPoolSize);
         }
         this.maximumPoolSize = maximumPoolSize;
     }
 
     /**
      * Sets the strategy to use for mapping AgiRequests to AgiScripts that serve them.
      *
      * @param mappingStrategy the mapping strategy to use.
      */
     public void setMappingStrategy(MappingStrategy mappingStrategy)
     {
         this.mappingStrategy = mappingStrategy;
     }
 
     protected MappingStrategy getMappingStrategy()
     {
         return mappingStrategy;
     }
 
     protected boolean isDie()
     {
         return die;
     }
 
     protected synchronized void shutdown()
     {
         this.die = true;
         if (pool != null)
         {
             pool.shutdown();
         }
     }
 
     @Override
     protected void finalize() throws Throwable
     {
         super.finalize();
 
         this.die = true;
         if (pool != null)
         {
             pool.shutdown();
         }
     }
 
     /**
      * Execute the runnable using the configured ThreadPoolExecutor obtained from {@link #getPool()}.
      *
      * @param command the command to run.
      * @throws RejectedExecutionException if the runnable can't be executed
      */
     protected void execute(Runnable command) throws RejectedExecutionException
     {
         if (isDie())
         {
             logger.warn("AgiServer is shutting down: Refused to execute AgiScript");
             return;
         }
 
         getPool().execute(command);
     }
 
     protected void handleException(String message, Exception e)
     {
         logger.warn(message, e);
     }
 
     private synchronized ThreadPoolExecutor getPool()
     {
         if (pool == null)
         {
             pool = createPool();
             logger.info("Thread pool started.");
         }
 
         return pool;
     }
 
     /**
      * Creates a new ThreadPoolExecutor to serve the AGI requests. The nature of this pool
      * defines how many concurrent requests can be handled. The default implementation
      * returns a dynamic thread pool defined by the poolSize and maximumPoolSize properties.<p>
      * You can override this method to change this behavior. For example you can use a cached
      * pool with
      * <pre>
      * return Executors.newCachedThreadPool(new DaemonThreadFactory());
      * </pre>
      *
      * @return the ThreadPoolExecutor to use for serving AGI requests.
      * @see #setPoolSize(int)
      * @see #setMaximumPoolSize(int)
      */
     protected ThreadPoolExecutor createPool()
     {
         return new ThreadPoolExecutor(
                 poolSize,
                 (maximumPoolSize < poolSize) ? poolSize : maximumPoolSize,
                 50000L, TimeUnit.MILLISECONDS,
                 new SynchronousQueue<Runnable>(),
                 new DaemonThreadFactory()
         );
     }
 }