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 package com.sun.grizzly;

 import java.util.concurrent.Callable;

 import java.util.concurrent.ConcurrentLinkedQueue;

 /**

  * This interface is responsible of handling {@link ConnectorHandler}

  * instance creation. This interface can be used to implement a connection

  * pooling mechanism.

  *

  * @param E ConnectorHandler implementation this pool will manage

  * @author Jeanfrancois

  */

 public interface ConnectorInstanceHandler<E extends ConnectorHandler> {

     /**

      * Acquire a {@link ConnectorHandler}

      * @return instance of ConnectorHandler

      */

     public E acquire();

     /**

      * Release a {@link ConnectorHandler}

      * @param connectorHandler release connector handler

      */

     public void release(E connectorHandler);

     /**

      * Concurrent Queue ConnectorInstanceHandler implementation

      * @param E ConnectorHandler implementation this pool will manage

      */

     public abstract class ConcurrentQueueConnectorInstanceHandler<E extends ConnectorHandler> implements ConnectorInstanceHandler<E> {

         /**

          * Simple queue used to pool {@link ConnectorHandler}

          */

         private ConcurrentLinkedQueue<E> pool;

         public ConcurrentQueueConnectorInstanceHandler(){

             pool = new ConcurrentLinkedQueue<E>();

         }

         /**

          * Acquire a {@link ConnectorHandler}

          */

         public E acquire(){

             E connectorHandler = pool.poll();

             if (connectorHandler == null){

                 connectorHandler = newInstance();

             }

             return connectorHandler;

         }

         /**

          * Release a {@link ConnectorHandler}

          */

         public void release(E connectorHandler){

             pool.offer(connectorHandler);

         }

         public abstract E newInstance();

     }

     /**

      * Concurrent Queue ConnectorInstanceHandler implementation

      * @param E ConnectorHandler implementation this pool will manage

      */

     public class ConcurrentQueueDelegateCIH<E extends ConnectorHandler> 

             extends ConcurrentQueueConnectorInstanceHandler<E> {

         // ConnectorHandler instance creator

         private Callable<E> delegate;

         public ConcurrentQueueDelegateCIH(Callable<E> delegate) {

             this.delegate = delegate;

         }

         public E newInstance() {

             try {

                 return delegate.call();

             } catch(Exception e) {

                 throw new IllegalStateException("Unexpected exception", e);

             }

         }

     }

 }