Synnefo » Pithos Android Client

/**

 *

 * Copyright (C) 2009 Cloud Conscious, LLC. <info@cloudconscious.com>

 *

 * ====================================================================

 * 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

 *

 * http://www.apache.org/licenses/LICENSE-2.0

 *

 * 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.jclouds.http.pool;

import java.io.IOException;

import java.net.URI;

import java.util.concurrent.BlockingQueue;

import java.util.concurrent.Semaphore;

import org.jclouds.http.HttpCommandRendezvous;

/**

 * Associates a command with an open connection to a service.

 * 

 * @author Adrian Cole

 */

public abstract class HttpCommandConnectionHandle<C> {

   protected final BlockingQueue<C> available;

   protected final Semaphore maxConnections;

   protected final Semaphore completed;

   protected final URI endPoint;

   protected C conn;

   protected HttpCommandRendezvous<?> command;

   public HttpCommandConnectionHandle(Semaphore maxConnections, BlockingQueue<C> available,

            URI endPoint, HttpCommandRendezvous<?> command, C conn) throws InterruptedException {

      this.available = available;

      this.maxConnections = maxConnections;

      this.completed = new Semaphore(1);

      this.endPoint = endPoint;

      this.command = command;

      this.conn = conn;

      completed.acquire();

   }

   public HttpCommandRendezvous<?> getCommandRendezvous() {

      return command;

   }

   public abstract void startConnection();

   public boolean isCompleted() {

      return (completed.availablePermits() == 1);

   }

   public void release() throws InterruptedException {

      if (isCompleted() || alreadyReleased()) {

         return;

      }

      available.put(conn);

      conn = null;

      command = null;

      completed.release();

   }

   private boolean alreadyReleased() {

      return conn == null;

   }

   public void cancel() throws IOException {

      if (isCompleted()) {

         return;

      }

      if (conn != null) {

         try {

            shutdownConnection();

         } finally {

            conn = null;

            command = null;

            maxConnections.release();

         }

      }

      completed.release();

   }

   public abstract void shutdownConnection() throws IOException;

   public void waitFor() throws InterruptedException {

      completed.acquire();

      completed.release();

   }

}