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 package com.sun.grizzly.util;

 import com.sun.grizzly.CallbackHandler;

 import java.nio.channels.SelectionKey;

 import java.util.concurrent.atomic.AtomicReference;

 /**

  * {@link SelectionKey} attachment, which wraps {@link CallbackHandler}

  * 

  * @author Alexey Stashok

  */

 public class CallbackHandlerSelectionKeyAttachment extends SelectionKeyAttachmentWrapper<CallbackHandler> {

     private static ConcurrentLinkedQueuePool<CallbackHandlerSelectionKeyAttachment> pool =

             new ConcurrentLinkedQueuePool<CallbackHandlerSelectionKeyAttachment>() {

                 @Override

                 public CallbackHandlerSelectionKeyAttachment newInstance() {

                     return new CallbackHandlerSelectionKeyAttachment();

                 }

             };

     // Is used for key pooling

     private AtomicReference<SelectionKey> associatedKey = new AtomicReference<SelectionKey>();

     /**

      * Creates the {@link CallbackHandler} to the {@link SelectionKey}

      * CallbackHandler will not be attached directly, but wrapped with 

      * <code>CallbackHandlerSelectionKeyAttachment</code>

      */

     public static CallbackHandlerSelectionKeyAttachment create(SelectionKey key, 

             CallbackHandler callbackHandler) {

         CallbackHandlerSelectionKeyAttachment attachment = pool.poll();

         attachment.associatedKey.set(key);

         attachment.setAttachment(callbackHandler);

         return attachment;

     }

     private CallbackHandlerSelectionKeyAttachment() {

     }

     @Override

     public void release(SelectionKey selectionKey) {

         if (associatedKey.getAndSet(null) == selectionKey) {

             super.release(selectionKey);

             pool.offer(this);

         }

     }

     /**

      * Callback handler never should lead to the timeout situation,

      * as connections could use it, but perform IO operations in sync. mode.

      * @return null

      */

     @Override

     public Long getTimeout() {

         return null;

     }

 }