//
   //  ========================================================================
   //  Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.client;
  
  import java.util.concurrent.atomic.AtomicReference;
  
  import org.eclipse.jetty.client.api.Result;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  
  public abstract class HttpChannel
  {
      protected static final Logger LOG = Log.getLogger(HttpChannel.class);
  
      private final AtomicReference<HttpExchange> exchange = new AtomicReference<>();
      private final HttpDestination destination;
  
      protected HttpChannel(HttpDestination destination)
      {
          this.destination = destination;
      }
  
      public HttpDestination getHttpDestination()
      {
          return destination;
      }
  
      public void associate(HttpExchange exchange)
      {
          if (this.exchange.compareAndSet(null, exchange))
          {
              exchange.associate(this);
              if (LOG.isDebugEnabled())
                  LOG.debug("{} associated to {}", exchange, this);
          }
          else
          {
              exchange.getRequest().abort(new UnsupportedOperationException("Pipelined requests not supported"));
          }
      }
  
      public HttpExchange disassociate()
      {
          HttpExchange exchange = this.exchange.getAndSet(null);
          if (exchange != null)
              exchange.disassociate(this);
          if (LOG.isDebugEnabled())
              LOG.debug("{} disassociated from {}", exchange, this);
          return exchange;
      }
  
      public HttpExchange getHttpExchange()
      {
          return exchange.get();
      }
  
      public abstract void send();
  
      public abstract void proceed(HttpExchange exchange, Throwable failure);
  
      public abstract boolean abort(Throwable cause);
  
      public void exchangeTerminated(Result result)
      {
          disassociate();
      }
  
      @Override
      public String toString()
      {
          return String.format("%s@%h", getClass().getSimpleName(), this);
      }
  }