// ========================================================================
   // Copyright (c) 2006-2009 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.io.IOException;
  import java.io.InputStream;
  import java.net.URI;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import org.eclipse.jetty.client.security.SecurityListener;
  import org.eclipse.jetty.http.HttpFields;
  import org.eclipse.jetty.http.HttpHeaders;
  import org.eclipse.jetty.http.HttpMethods;
  import org.eclipse.jetty.http.HttpSchemes;
  import org.eclipse.jetty.http.HttpURI;
  import org.eclipse.jetty.http.HttpVersions;
  import org.eclipse.jetty.io.Buffer;
  import org.eclipse.jetty.io.BufferCache.CachedBuffer;
  import org.eclipse.jetty.io.ByteArrayBuffer;
  import org.eclipse.jetty.io.Connection;
  import org.eclipse.jetty.io.EndPoint;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  import org.eclipse.jetty.util.thread.Timeout;
  
  /**
   * <p>An HTTP client API that encapsulates an exchange (a request and its response) with a HTTP server.</p>
   *
   * This object encapsulates:
   * <ul>
   * <li>The HTTP server address, see {@link #setAddress(Address)}, or {@link #setURI(URI)}, or {@link #setURL(String)})
   * <li>The HTTP request method, URI and HTTP version (see {@link #setMethod(String)}, {@link #setRequestURI(String)}, and {@link #setVersion(int)})
   * <li>The request headers (see {@link #addRequestHeader(String, String)} or {@link #setRequestHeader(String, String)})
   * <li>The request content (see {@link #setRequestContent(Buffer)} or {@link #setRequestContentSource(InputStream)})
   * <li>The status of the exchange (see {@link #getStatus()})
   * <li>Callbacks to handle state changes (see the onXxx methods such as {@link #onRequestComplete()} or {@link #onResponseComplete()})
   * <li>The ability to intercept callbacks (see {@link #setEventListener(HttpEventListener)}
   * </ul>
   *
   * <p>The HttpExchange class is intended to be used by a developer wishing to have close asynchronous
   * interaction with the the exchange.<br />
   * Typically a developer will extend the HttpExchange class with a derived
   * class that overrides some or all of the onXxx callbacks. <br />
   * There are also some predefined HttpExchange subtypes that can be used as a basis,
   * see {@link org.eclipse.jetty.client.ContentExchange} and {@link org.eclipse.jetty.client.CachedExchange}.</p>
   *
   * <p>Typically the HttpExchange is passed to the {@link HttpClient#send(HttpExchange)} method, which in
   * turn selects a {@link HttpDestination} and calls its {@link HttpDestination#send(HttpExchange)}, which
   * then creates or selects a {@link HttpConnection} and calls its {@link HttpConnection#send(HttpExchange)}.
   * A developer may wish to directly call send on the destination or connection if they wish to bypass
   * some handling provided (eg Cookie handling in the HttpDestination).</p>
   *
   * <p>In some circumstances, the HttpClient or HttpDestination may wish to retry a HttpExchange (eg. failed
   * pipeline request, authentication retry or redirection).  In such cases, the HttpClient and/or HttpDestination
   * may insert their own HttpExchangeListener to intercept and filter the call backs intended for the
   * HttpExchange.</p>
   */
  public class HttpExchange
  {
      private static final Logger LOG = Log.getLogger(HttpExchange.class);
  
      public static final int STATUS_START = 0;
      public static final int STATUS_WAITING_FOR_CONNECTION = 1;
      public static final int STATUS_WAITING_FOR_COMMIT = 2;
      public static final int STATUS_SENDING_REQUEST = 3;
      public static final int STATUS_WAITING_FOR_RESPONSE = 4;
      public static final int STATUS_PARSING_HEADERS = 5;
      public static final int STATUS_PARSING_CONTENT = 6;
      public static final int STATUS_COMPLETED = 7;
      public static final int STATUS_EXPIRED = 8;
      public static final int STATUS_EXCEPTED = 9;
      public static final int STATUS_CANCELLING = 10;
      public static final int STATUS_CANCELLED = 11;
  
      // HTTP protocol fields
      private String _method = HttpMethods.GET;
      private Buffer _scheme = HttpSchemes.HTTP_BUFFER;
      private String _uri;
      private int _version = HttpVersions.HTTP_1_1_ORDINAL;
      private Address _address;
      private final HttpFields _requestFields = new HttpFields();
      private Buffer _requestContent;
      private InputStream _requestContentSource;
  
      private AtomicInteger _status = new AtomicInteger(STATUS_START);
      private Buffer _requestContentChunk;
      private boolean _retryStatus = false;
      // controls if the exchange will have listeners autoconfigured by the destination
     private boolean _configureListeners = true;
     private HttpEventListener _listener = new Listener();
     private volatile HttpConnection _connection;
 
     private Address _localAddress = null;
 
     // a timeout for this exchange
     private long _timeout = -1;
     private volatile Timeout.Task _timeoutTask;
     
     private long _lastStateChange=-1;
     private long _sent=-1;
 
     boolean _onRequestCompleteDone;
     boolean _onResponseCompleteDone;
     boolean _onDone; // == onConnectionFail || onException || onExpired || onCancelled || onResponseCompleted && onRequestCompleted
 
     protected void expire(HttpDestination destination)
     {
         if (getStatus() < HttpExchange.STATUS_COMPLETED)
             setStatus(HttpExchange.STATUS_EXPIRED);
 
         destination.exchangeExpired(this);
         HttpConnection connection = _connection;
         if (connection != null)
             connection.exchangeExpired(this);
     }
 
     public int getStatus()
     {
         return _status.get();
     }
 
     /**
      * @param status the status to wait for
      * @throws InterruptedException if the waiting thread is interrupted
      * @deprecated Use {@link #waitForDone()} instead
      */
     @Deprecated
     public void waitForStatus(int status) throws InterruptedException
     {
         throw new UnsupportedOperationException();
     }
 
     /**
      * Wait until the exchange is "done".
      * Done is defined as when a final state has been passed to the
      * HttpExchange via the associated onXxx call.  Note that an
      * exchange can transit a final state when being used as part
      * of a dialog (eg {@link SecurityListener}.   Done status
      * is thus defined as:<pre>
      *   done == onConnectionFailed
      *        || onException
      *        || onExpire
      *        || onRequestComplete && onResponseComplete
      * </pre>
      * @return the done status
      * @throws InterruptedException
      */
     public int waitForDone () throws InterruptedException
     {
         synchronized (this)
         {
             while (!isDone())
                 this.wait();
             return _status.get();
         }
     }
 
     public void reset()
     {
         // TODO - this should do a cancel and wakeup everybody that was waiting.
         // might need a version number concept
         synchronized(this)
         {
             _timeoutTask=null;
             _onRequestCompleteDone=false;
             _onResponseCompleteDone=false;
             _onDone=false;
             setStatus(STATUS_START);
         }
     }
 
     void setStatus(int newStatus)
     {
         try
         {
             int oldStatus = _status.get();
             boolean set = false;
             if (oldStatus!=newStatus)
             {
                 _lastStateChange=System.currentTimeMillis();
                 if (newStatus==STATUS_SENDING_REQUEST)
                     _sent=_lastStateChange;
             }
             
             // State machine: from which old status you can go into which new status
             switch (oldStatus)
             {
                 case STATUS_START:
                     switch (newStatus)
                     {
                         case STATUS_START:
                         case STATUS_WAITING_FOR_CONNECTION:
                         case STATUS_WAITING_FOR_COMMIT:
                         case STATUS_CANCELLING:
                         case STATUS_EXCEPTED:
                             set=_status.compareAndSet(oldStatus,newStatus);
                             break;
                     }
                     break;
                 case STATUS_WAITING_FOR_CONNECTION:
                     switch (newStatus)
                     {
                         case STATUS_WAITING_FOR_COMMIT:
                         case STATUS_CANCELLING:
                         case STATUS_EXCEPTED:
                             set=_status.compareAndSet(oldStatus,newStatus);
                             break;
                         case STATUS_EXPIRED:
                             if (set=_status.compareAndSet(oldStatus,newStatus))
                                 getEventListener().onExpire();
                             break;
                     }
                     break;
                 case STATUS_WAITING_FOR_COMMIT:
                     switch (newStatus)
                     {
                         case STATUS_SENDING_REQUEST:
                         case STATUS_CANCELLING:
                         case STATUS_EXCEPTED:
                             set=_status.compareAndSet(oldStatus,newStatus);
                             break;
                         case STATUS_EXPIRED:
                             if (set=_status.compareAndSet(oldStatus,newStatus))
                                 getEventListener().onExpire();
                             break;
                     }
                     break;
                 case STATUS_SENDING_REQUEST:
                     switch (newStatus)
                     {
                         case STATUS_WAITING_FOR_RESPONSE:
                             if (set=_status.compareAndSet(oldStatus,newStatus))
                                 getEventListener().onRequestCommitted();
                             break;
                         case STATUS_CANCELLING:
                         case STATUS_EXCEPTED:
                             set=_status.compareAndSet(oldStatus,newStatus);
                             break;
                         case STATUS_EXPIRED:
                             if (set=_status.compareAndSet(oldStatus,newStatus))
                                 getEventListener().onExpire();
                             break;
                     }
                     break;
                 case STATUS_WAITING_FOR_RESPONSE:
                     switch (newStatus)
                     {
                         case STATUS_PARSING_HEADERS:
                         case STATUS_CANCELLING:
                         case STATUS_EXCEPTED:
                             set=_status.compareAndSet(oldStatus,newStatus);
                             break;
                         case STATUS_EXPIRED:
                             if (set=_status.compareAndSet(oldStatus,newStatus))
                                 getEventListener().onExpire();
                             break;
                     }
                     break;
                 case STATUS_PARSING_HEADERS:
                     switch (newStatus)
                     {
                         case STATUS_PARSING_CONTENT:
                             if (set=_status.compareAndSet(oldStatus,newStatus))
                                 getEventListener().onResponseHeaderComplete();
                             break;
                         case STATUS_CANCELLING:
                         case STATUS_EXCEPTED:
                             set=_status.compareAndSet(oldStatus,newStatus);
                             break;
                         case STATUS_EXPIRED:
                             if (set=_status.compareAndSet(oldStatus,newStatus))
                                 getEventListener().onExpire();
                             break;
                     }
                     break;
                 case STATUS_PARSING_CONTENT:
                     switch (newStatus)
                     {
                         case STATUS_COMPLETED:
                             if (set=_status.compareAndSet(oldStatus,newStatus))
                                 getEventListener().onResponseComplete();
                             break;
                         case STATUS_CANCELLING:
                         case STATUS_EXCEPTED:
                             set=_status.compareAndSet(oldStatus,newStatus);
                             break;
                         case STATUS_EXPIRED:
                             if (set=_status.compareAndSet(oldStatus,newStatus))
                                 getEventListener().onExpire();
                             break;
                     }
                     break;
                 case STATUS_COMPLETED:
                     switch (newStatus)
                     {
                         case STATUS_START:
                         case STATUS_EXCEPTED:
                         case STATUS_WAITING_FOR_RESPONSE:
                             set=_status.compareAndSet(oldStatus,newStatus);
                             break;
                         case STATUS_CANCELLING:
                         case STATUS_EXPIRED:
                             // Don't change the status, it's too late
                             set=true;
                             break;
                     }
                     break;
                 case STATUS_CANCELLING:
                     switch (newStatus)
                     {
                         case STATUS_EXCEPTED:
                         case STATUS_CANCELLED:
                             if (set=_status.compareAndSet(oldStatus,newStatus))
                                 done();
                             break;
                         default:
                             // Ignore other statuses, we're cancelling
                             set=true;
                             break;
                     }
                     break;
                 case STATUS_EXCEPTED:
                 case STATUS_EXPIRED:
                 case STATUS_CANCELLED:
                     switch (newStatus)
                     {
                         case STATUS_START:
                             set=_status.compareAndSet(oldStatus,newStatus);
                             break;
                         default:
                             set=true;
                             break;
                     }
                     break;
                 default:
                     // Here means I allowed to set a state that I don't recognize
                     throw new AssertionError(oldStatus + " => " + newStatus);
             }
 
             if (!set)
                 throw new IllegalStateException(toState(oldStatus) + " => " + toState(newStatus));
         }
         catch (IOException x)
         {
             LOG.warn(x);
         }
     }
 
     public boolean isDone()
     {
         synchronized (this)
         {
             return _onDone;
         }
     }
 
     /**
      * @deprecated
      */
     @Deprecated
     public boolean isDone (int status)
     {
         return isDone();
     }
 
     public HttpEventListener getEventListener()
     {
         return _listener;
     }
 
     public void setEventListener(HttpEventListener listener)
     {
         _listener=listener;
     }
 
     public void setTimeout( long timeout )
     {
         _timeout = timeout;
     }
 
     public long getTimeout()
     {
         return _timeout;
     }
 
     /**
      * @param url an absolute URL (for example 'http://localhost/foo/bar?a=1') 
      */
     public void setURL(String url)
     {
         setURI(URI.create(url));
     }
 
     /**
      * @param address the address of the server
      */
     public void setAddress(Address address)
     {
         _address = address;
     }
 
     /**
      * @return the address of the server
      */
     public Address getAddress()
     {
         return _address;
     }
 
     /**
      * the local address used by the connection
      *
      * Note: this method will not be populated unless the exchange
      * has been executed by the HttpClient
      *
      * @return the local address used for the running of the exchange if available, null otherwise.
      */
     public Address getLocalAddress()
     {
         return _localAddress;
     }
 
     /**
      * @param scheme the scheme of the URL (for example 'http')
      */
     public void setScheme(Buffer scheme)
     {
         _scheme = scheme;
     }
     
     /**
      * @param scheme the scheme of the URL (for example 'http')
      */
     public void setScheme(String scheme)
     {
         if (scheme != null)
         {
             if (HttpSchemes.HTTP.equalsIgnoreCase(scheme))
                 setScheme(HttpSchemes.HTTP_BUFFER);
             else if (HttpSchemes.HTTPS.equalsIgnoreCase(scheme))
                 setScheme(HttpSchemes.HTTPS_BUFFER);
             else
                 setScheme(new ByteArrayBuffer(scheme));
         }
     }
 
     /**
      * @return the scheme of the URL
      */
     public Buffer getScheme()
     {
         return _scheme;
     }
 
     /**
      * @param version the HTTP protocol version as integer, 9, 10 or 11 for 0.9, 1.0 or 1.1
      */
     public void setVersion(int version)
     {
         _version = version;
     }
 
     /**
      * @param version the HTTP protocol version as string
      */
     public void setVersion(String version)
     {
         CachedBuffer v = HttpVersions.CACHE.get(version);
         if (v == null)
             _version = 10;
         else
             _version = v.getOrdinal();
     }
 
     /**
      * @return the HTTP protocol version as integer
      * @see #setVersion(int)
      */
     public int getVersion()
     {
         return _version;
     }
 
     /**
      * @param method the HTTP method (for example 'GET')
      */
     public void setMethod(String method)
     {
         _method = method;
     }
 
     /**
      * @return the HTTP method
      */
     public String getMethod()
     {
         return _method;
     }
 
     /**
      * @return request URI
      * @see #getRequestURI()
      * @deprecated
      */
     @Deprecated
     public String getURI()
     {
         return getRequestURI();
     }
 
     /**
      * @return request URI
      */
     public String getRequestURI()
     {
         return _uri;
     }
 
     /**
      * Set the request URI 
      *
      * @param uri new request URI
      * @see #setRequestURI(String)
      * @deprecated
      */
     @Deprecated
     public void setURI(String uri)
     {
         setRequestURI(uri);
     }
 
     /**
      * Set the request URI 
      *
      * Per RFC 2616 sec5, Request-URI = "*" | absoluteURI | abs_path | authority<br/>
      * where:<br/><br/>
      * "*"         - request applies to server itself<br/>
      * absoluteURI - required for proxy requests, e.g. http://localhost:8080/context<br/>
      *               (this form is generated automatically by HttpClient)<br/>
      * abs_path    - used for most methods, e.g. /context<br/>
      * authority   - used for CONNECT method only, e.g. localhost:8080<br/>
      * <br/>
      * For complete definition of URI components, see RFC 2396 sec3.<br/>
      * 
      * @param uri new request URI
      */
     public void setRequestURI(String uri)
     {
         _uri = uri;
     }
     
     /* ------------------------------------------------------------ */
     /**
      * @param uri an absolute URI (for example 'http://localhost/foo/bar?a=1') 
      */
     public void setURI(URI uri)
     {
         if (!uri.isAbsolute())
             throw new IllegalArgumentException("!Absolute URI: "+uri);
             
         if (uri.isOpaque())
             throw new IllegalArgumentException("Opaque URI: "+uri);
 
         String scheme = uri.getScheme();
         int port = uri.getPort();
         if (port <= 0)
             port = "https".equalsIgnoreCase(scheme)?443:80;
 
         setScheme(scheme);
         setAddress(new Address(uri.getHost(),port));
 
         HttpURI httpUri = new HttpURI(uri);
         String completePath = httpUri.getCompletePath();
         setRequestURI(completePath==null ? "/" : completePath);
     }
 
     /**
      * Adds the specified request header
      * @param name the header name
      * @param value the header value
      */
     public void addRequestHeader(String name, String value)
     {
         getRequestFields().add(name,value);
     }
 
     /**
      * Adds the specified request header
      * @param name the header name
      * @param value the header value
      */
     public void addRequestHeader(Buffer name, Buffer value)
     {
         getRequestFields().add(name,value);
     }
 
     /**
      * Sets the specified request header
      * @param name the header name
      * @param value the header value
      */
     public void setRequestHeader(String name, String value)
     {
         getRequestFields().put(name, value);
     }
 
     /**
      * Sets the specified request header
      * @param name the header name
      * @param value the header value
      */
     public void setRequestHeader(Buffer name, Buffer value)
     {
         getRequestFields().put(name, value);
     }
 
     /**
      * @param value the content type of the request
      */
     public void setRequestContentType(String value)
     {
         getRequestFields().put(HttpHeaders.CONTENT_TYPE_BUFFER, value);
     }
 
     /**
      * @return the request headers
      */
     public HttpFields getRequestFields()
     {
         return _requestFields;
     }
 
     /**
      * @param requestContent the request content
      */
     public void setRequestContent(Buffer requestContent)
     {
         _requestContent = requestContent;
     }
 
     /**
      * @param stream the request content as a stream
      */
     public void setRequestContentSource(InputStream stream)
     {
         _requestContentSource = stream;
         if (_requestContentSource != null && _requestContentSource.markSupported())
             _requestContentSource.mark(Integer.MAX_VALUE);
     }
 
     /**
      * @return the request content as a stream
      */
     public InputStream getRequestContentSource()
     {
         return _requestContentSource;
     }
 
     public Buffer getRequestContentChunk() throws IOException
     {
         synchronized (this)
         {
             if (_requestContentChunk == null)
                 _requestContentChunk = new ByteArrayBuffer(4096); // TODO configure
             else
             {
                 if (_requestContentChunk.hasContent())
                     throw new IllegalStateException();
                 _requestContentChunk.clear();
             }
 
             int read = _requestContentChunk.capacity();
             int length = _requestContentSource.read(_requestContentChunk.array(),0,read);
             if (length >= 0)
             {
                 _requestContentChunk.setPutIndex(length);
                 return _requestContentChunk;
             }
             return null;
         }
     }
 
     /**
      * @return the request content
      */
     public Buffer getRequestContent()
     {
         return _requestContent;
     }
 
     /**
      * @return whether a retry will be attempted or not
      */
     public boolean getRetryStatus()
     {
         return _retryStatus;
     }
 
     /**
      * @param retryStatus whether a retry will be attempted or not
      */
     public void setRetryStatus(boolean retryStatus)
     {
         _retryStatus = retryStatus;
     }
 
     /**
      * Initiates the cancelling of this exchange.
      * The status of the exchange is set to {@link #STATUS_CANCELLING}.
      * Cancelling the exchange is an asynchronous operation with respect to the request/response,
      * and as such checking the request/response status of a cancelled exchange may return undefined results
      * (for example it may have only some of the response headers being sent by the server).
      * The cancelling of the exchange is completed when the exchange status (see {@link #getStatus()}) is
      * {@link #STATUS_CANCELLED}, and this can be waited using {@link #waitForDone()}.
      */
     public void cancel()
     {
         setStatus(STATUS_CANCELLING);
         abort();
     }
 
     private void done()
     {
         synchronized(this)
         {
             disassociate();
             _onDone=true;
             notifyAll();
         }
     }
 
     private void abort()
     {
         HttpConnection httpConnection = _connection;
         if (httpConnection != null)
         {
             try
             {
                 // Closing the connection here will cause the connection
                 // to be returned in HttpConnection.handle()
                 httpConnection.close();
             }
             catch (IOException x)
             {
                 LOG.debug(x);
             }
             finally
             {
                 disassociate();
             }
         }
     }
 
     void associate(HttpConnection connection)
     {
        if (connection.getEndPoint().getLocalHost() != null)
            _localAddress = new Address(connection.getEndPoint().getLocalHost(), connection.getEndPoint().getLocalPort());
 
         _connection = connection;
         if (getStatus() == STATUS_CANCELLING)
             abort();
     }
 
     boolean isAssociated()
     {
         return this._connection != null;
     }
 
     HttpConnection disassociate()
     {
         HttpConnection result = _connection;
         this._connection = null;
         if (getStatus() == STATUS_CANCELLING)
             setStatus(STATUS_CANCELLED);
         return result;
     }
 
     public static String toState(int s)
     {
         String state;
         switch(s)
         {
             case STATUS_START: state="START"; break;
             case STATUS_WAITING_FOR_CONNECTION: state="CONNECTING"; break;
             case STATUS_WAITING_FOR_COMMIT: state="CONNECTED"; break;
             case STATUS_SENDING_REQUEST: state="SENDING"; break;
             case STATUS_WAITING_FOR_RESPONSE: state="WAITING"; break;
             case STATUS_PARSING_HEADERS: state="HEADERS"; break;
             case STATUS_PARSING_CONTENT: state="CONTENT"; break;
             case STATUS_COMPLETED: state="COMPLETED"; break;
             case STATUS_EXPIRED: state="EXPIRED"; break;
             case STATUS_EXCEPTED: state="EXCEPTED"; break;
             case STATUS_CANCELLING: state="CANCELLING"; break;
             case STATUS_CANCELLED: state="CANCELLED"; break;
             default: state="UNKNOWN";
         }
         return state;
     }
     
     @Override
     public String toString()
     {
         String state=toState(getStatus());
         long now=System.currentTimeMillis();
         long forMs = now -_lastStateChange;
         String s= String.format("%s@%x=%s//%s%s#%s(%dms)",getClass().getSimpleName(),hashCode(),_method,_address,_uri,state,forMs);
         if (getStatus()>=STATUS_SENDING_REQUEST)
             s+="sent="+(now-_sent)+"ms";
         return s;
     }
 
     /**
      */
     protected Connection onSwitchProtocol(EndPoint endp) throws IOException
     {
         return null;
     }
 
     /**
      * Callback called when the request headers have been sent to the server.
      * This implementation does nothing.
      * @throws IOException allowed to be thrown by overriding code
      */
     protected void onRequestCommitted() throws IOException
     {
     }
 
     /**
      * Callback called when the request and its body have been sent to the server.
      * This implementation does nothing.
      * @throws IOException allowed to be thrown by overriding code
      */
     protected void onRequestComplete() throws IOException
     {
     }
 
     /**
      * Callback called when a response status line has been received from the server.
      * This implementation does nothing.
      * @param version the HTTP version
      * @param status the HTTP status code
      * @param reason the HTTP status reason string
      * @throws IOException allowed to be thrown by overriding code
      */
     protected void onResponseStatus(Buffer version, int status, Buffer reason) throws IOException
     {
     }
 
     /**
      * Callback called for each response header received from the server.
      * This implementation does nothing.
      * @param name the header name
      * @param value the header value
      * @throws IOException allowed to be thrown by overriding code
      */
     protected void onResponseHeader(Buffer name, Buffer value) throws IOException
     {
     }
 
     /**
      * Callback called when the response headers have been completely received from the server.
      * This implementation does nothing.
      * @throws IOException allowed to be thrown by overriding code
      */
     protected void onResponseHeaderComplete() throws IOException
     {
     }
 
     /**
      * Callback called for each chunk of the response content received from the server.
      * This implementation does nothing.
      * @param content the buffer holding the content chunk
      * @throws IOException allowed to be thrown by overriding code
      */
     protected void onResponseContent(Buffer content) throws IOException
     {
     }
 
     /**
      * Callback called when the entire response has been received from the server
      * This implementation does nothing.
      * @throws IOException allowed to be thrown by overriding code
      */
     protected void onResponseComplete() throws IOException
     {
     }
 
     /**
      * Callback called when an exception was thrown during an attempt to establish the connection
      * with the server (for example the server is not listening).
      * This implementation logs a warning.
      * @param x the exception thrown attempting to establish the connection with the server
      */
     protected void onConnectionFailed(Throwable x)
     {
         LOG.warn("CONNECTION FAILED " + this,x);
     }
 
     /**
      * Callback called when any other exception occurs during the handling of this exchange.
      * This implementation logs a warning.
      * @param x the exception thrown during the handling of this exchange
      */
     protected void onException(Throwable x)
     {
         LOG.warn("EXCEPTION " + this,x);
     }
 
     /**
      * Callback called when no response has been received within the timeout.
      * This implementation logs a warning.
      */
     protected void onExpire()
     {
         LOG.warn("EXPIRED " + this);
     }
 
     /**
      * Callback called when the request is retried (due to failures or authentication).
      * Implementations must reset any consumable content that needs to be sent.
      * @throws IOException allowed to be thrown by overriding code
      */
     protected void onRetry() throws IOException
     {
         if (_requestContentSource != null)
         {
             if (_requestContentSource.markSupported())
             {
                 _requestContent = null;
                 _requestContentSource.reset();
             }
             else
             {
                 throw new IOException("Unsupported retry attempt");
             }
         }
     }
 
     /**
      * @return true if the exchange should have listeners configured for it by the destination,
      * false if this is being managed elsewhere
      * @see #setConfigureListeners(boolean)
      */
     public boolean configureListeners()
     {
         return _configureListeners;
     }
 
     /**
      * @param autoConfigure whether the listeners are configured by the destination or elsewhere
      */
     public void setConfigureListeners(boolean autoConfigure)
     {
         this._configureListeners = autoConfigure;
     }
 
     protected void scheduleTimeout(final HttpDestination destination)
     {
         assert _timeoutTask == null;
 
         _timeoutTask = new Timeout.Task()
         {
             @Override
             public void expired()
             {
                 HttpExchange.this.expire(destination);
             }
         };
 
         HttpClient httpClient = destination.getHttpClient();
         long timeout = getTimeout();
         if (timeout > 0)
             httpClient.schedule(_timeoutTask, timeout);
         else
             httpClient.schedule(_timeoutTask);
     }
 
     protected void cancelTimeout(HttpClient httpClient)
     {
         Timeout.Task task = _timeoutTask;
         if (task != null)
             httpClient.cancel(task);
         _timeoutTask = null;
     }
 
     private class Listener implements HttpEventListener
     {
         public void onConnectionFailed(Throwable ex)
         {
             try
             {
                 HttpExchange.this.onConnectionFailed(ex);
             }
             finally
             {
                 done();
             }
         }
 
         public void onException(Throwable ex)
         {
             try
             {
                 HttpExchange.this.onException(ex);
             }
             finally
             {
                 done();
             }
         }
 
         public void onExpire()
         {
             try
             {
                 HttpExchange.this.onExpire();
             }
             finally
             {
                 done();
             }
         }
 
         public void onRequestCommitted() throws IOException
         {
             HttpExchange.this.onRequestCommitted();
         }
 
         public void onRequestComplete() throws IOException
         {
             try
             {
                 HttpExchange.this.onRequestComplete();
             }
             finally
             {
                 synchronized(HttpExchange.this)
                 {
                     _onRequestCompleteDone = true;
                     // Member _onDone may already be true, for example
                     // because the exchange expired or has been canceled
                     _onDone |= _onResponseCompleteDone;
                     if (_onDone)
                         disassociate();
                     HttpExchange.this.notifyAll();
                 }
             }
         }
 
         public void onResponseComplete() throws IOException
         {
             try
             {
                 HttpExchange.this.onResponseComplete();
             }
             finally
             {
                 synchronized(HttpExchange.this)
                 {
                     _onResponseCompleteDone = true;
                     // Member _onDone may already be true, for example
                     // because the exchange expired or has been canceled
                     _onDone |= _onRequestCompleteDone;
                     if (_onDone)
                         disassociate();
                     HttpExchange.this.notifyAll();
                 }
             }
         }
 
         public void onResponseContent(Buffer content) throws IOException
         {
             HttpExchange.this.onResponseContent(content);
         }
 
         public void onResponseHeader(Buffer name, Buffer value) throws IOException
         {
             HttpExchange.this.onResponseHeader(name,value);
         }
 
         public void onResponseHeaderComplete() throws IOException
         {
             HttpExchange.this.onResponseHeaderComplete();
         }
 
         public void onResponseStatus(Buffer version, int status, Buffer reason) throws IOException
         {
             HttpExchange.this.onResponseStatus(version,status,reason);
         }
 
         public void onRetry()
         {
             HttpExchange.this.setRetryStatus( true );
             try
             {
                 HttpExchange.this.onRetry();
             }
             catch (IOException e)
             {
                 LOG.debug(e);
             }
         }
     }
 
     /**
      * @deprecated use {@link org.eclipse.jetty.client.CachedExchange} instead
      */
     @Deprecated
     public static class CachedExchange extends org.eclipse.jetty.client.CachedExchange
     {
         public CachedExchange(boolean cacheFields)
         {
             super(cacheFields);
         }
     }
 
     /**
      * @deprecated use {@link org.eclipse.jetty.client.ContentExchange} instead
      */
     @Deprecated
     public static class ContentExchange extends org.eclipse.jetty.client.ContentExchange
     {
     }
 }