/*
    * ====================================================================
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  
  package org.apache.http.nio.protocol;
  
  import java.io.Closeable;
  import java.io.IOException;
  import java.net.SocketTimeoutException;
  
  import org.apache.http.ConnectionReuseStrategy;
  import org.apache.http.HttpConnection;
  import org.apache.http.HttpEntity;
  import org.apache.http.HttpEntityEnclosingRequest;
  import org.apache.http.HttpException;
  import org.apache.http.HttpRequest;
  import org.apache.http.HttpResponse;
  import org.apache.http.HttpResponseFactory;
  import org.apache.http.HttpStatus;
  import org.apache.http.HttpVersion;
  import org.apache.http.MethodNotSupportedException;
  import org.apache.http.ProtocolException;
  import org.apache.http.UnsupportedHttpVersionException;
  import org.apache.http.annotation.Immutable;
  import org.apache.http.concurrent.Cancellable;
  import org.apache.http.entity.ContentType;
  import org.apache.http.impl.DefaultConnectionReuseStrategy;
  import org.apache.http.impl.DefaultHttpResponseFactory;
  import org.apache.http.nio.ContentDecoder;
  import org.apache.http.nio.ContentEncoder;
  import org.apache.http.nio.NHttpConnection;
  import org.apache.http.nio.NHttpServerConnection;
  import org.apache.http.nio.NHttpServerEventHandler;
  import org.apache.http.nio.entity.NStringEntity;
  import org.apache.http.params.HttpParams;
  import org.apache.http.protocol.BasicHttpContext;
  import org.apache.http.protocol.ExecutionContext;
  import org.apache.http.protocol.HttpContext;
  import org.apache.http.protocol.HttpProcessor;
  import org.apache.http.util.Args;
  import org.apache.http.util.Asserts;
  
  /**
   * <tt>HttpAsyncService</tt> is a fully asynchronous HTTP server side protocol
   * handler based on the non-blocking (NIO) I/O model.
   * <tt>HttpAsyncServerProtocolHandler</tt> translates individual events fired
   * through the {@link NHttpServerEventHandler} interface into logically related
   * HTTP message exchanges.
   * <p/>
   * Upon receiving an incoming request <tt>HttpAsyncService</tt> verifies
   * the message for compliance with the server expectations using
   * {@link HttpAsyncExpectationVerifier}, if provided, and then
   * {@link HttpAsyncRequestHandlerMapper} is used to map the request
   * to a particular {@link HttpAsyncRequestHandler} intended to handle
   * the request with the given URI. The protocol handler uses the selected
   * {@link HttpAsyncRequestHandler} instance to process the incoming request
   * and to generate an outgoing response.
   * <p/>
   * <tt>HttpAsyncService</tt> relies on {@link HttpProcessor} to generate
   * mandatory protocol headers for all outgoing messages and apply common,
   * cross-cutting message transformations to all incoming and outgoing messages,
   * whereas individual {@link HttpAsyncRequestHandler}s are expected
   * to implement application specific content generation and processing.
   * <p/>
   * Individual {@link HttpAsyncRequestHandler}s do not have to submit a response
   * immediately. They can defer transmission of an HTTP response back to
   * the client without blocking the I/O thread by delegating the process of
   * request handling to another service or a worker thread. HTTP response can
   * be submitted as a later a later point of time once response content becomes
   * available.
   *
   * @since 4.2
   */
  @SuppressWarnings("deprecation")
  @Immutable // provided injected dependencies are immutable
  public class HttpAsyncService implements NHttpServerEventHandler {
 
     static final String HTTP_EXCHANGE_STATE = "http.nio.http-exchange-state";
 
     private final HttpProcessor httpProcessor;
     private final ConnectionReuseStrategy connStrategy;
     private final HttpResponseFactory responseFactory;
     private final HttpAsyncRequestHandlerMapper handlerMapper;
     private final HttpAsyncExpectationVerifier expectationVerifier;
 
     /**
      * Creates new instance of <tt>HttpAsyncServerProtocolHandler</tt>.
      *
      * @param httpProcessor HTTP protocol processor (required).
      * @param connStrategy Connection re-use strategy (required).
      * @param responseFactory HTTP response factory (required).
      * @param handlerResolver Request handler resolver.
      * @param expectationVerifier Request expectation verifier (optional).
      * @param params HTTP parameters (required).
      *
      * @deprecated (4.3) use {@link HttpAsyncService#HttpAsyncService(HttpProcessor,
      *  ConnectionReuseStrategy, HttpResponseFactory, HttpAsyncRequestHandlerMapper,
      *    HttpAsyncExpectationVerifier)}
      */
     @Deprecated
     public HttpAsyncService(
             final HttpProcessor httpProcessor,
             final ConnectionReuseStrategy connStrategy,
             final HttpResponseFactory responseFactory,
             final HttpAsyncRequestHandlerResolver handlerResolver,
             final HttpAsyncExpectationVerifier expectationVerifier,
             final HttpParams params) {
         this(httpProcessor,
              connStrategy,
              responseFactory,
              new HttpAsyncRequestHandlerResolverAdapter(handlerResolver),
              expectationVerifier);
     }
 
     /**
      * Creates new instance of <tt>HttpAsyncServerProtocolHandler</tt>.
      *
      * @param httpProcessor HTTP protocol processor (required).
      * @param connStrategy Connection re-use strategy (required).
      * @param handlerResolver Request handler resolver.
      * @param params HTTP parameters (required).
      *
      * @deprecated (4.3) use {@link HttpAsyncService#HttpAsyncService(HttpProcessor,
      *   ConnectionReuseStrategy, HttpResponseFactory, HttpAsyncRequestHandlerMapper,
      *   HttpAsyncExpectationVerifier)}
      */
     @Deprecated
     public HttpAsyncService(
             final HttpProcessor httpProcessor,
             final ConnectionReuseStrategy connStrategy,
             final HttpAsyncRequestHandlerResolver handlerResolver,
             final HttpParams params) {
         this(httpProcessor,
              connStrategy,
              DefaultHttpResponseFactory.INSTANCE,
              new HttpAsyncRequestHandlerResolverAdapter(handlerResolver),
              null);
     }
 
     /**
      * Creates new instance of <tt>HttpAsyncServerProtocolHandler</tt>.
      *
      * @param httpProcessor HTTP protocol processor.
      * @param connStrategy Connection re-use strategy. If <code>null</code>
      *   {@link DefaultConnectionReuseStrategy#INSTANCE} will be used.
      * @param responseFactory HTTP response factory. If <code>null</code>
      *   {@link DefaultHttpResponseFactory#INSTANCE} will be used.
      * @param handlerMapper Request handler mapper.
      * @param expectationVerifier Request expectation verifier. May be <code>null</code>.
      *
      * @since 4.3
      */
     public HttpAsyncService(
             final HttpProcessor httpProcessor,
             final ConnectionReuseStrategy connStrategy,
             final HttpResponseFactory responseFactory,
             final HttpAsyncRequestHandlerMapper handlerMapper,
             final HttpAsyncExpectationVerifier expectationVerifier) {
         super();
         this.httpProcessor = Args.notNull(httpProcessor, "HTTP processor");
         this.connStrategy = connStrategy != null ? connStrategy :
             DefaultConnectionReuseStrategy.INSTANCE;
         this.responseFactory = responseFactory != null ? responseFactory :
             DefaultHttpResponseFactory.INSTANCE;
         this.handlerMapper = handlerMapper;
         this.expectationVerifier = expectationVerifier;
     }
 
     /**
      * Creates new instance of <tt>HttpAsyncServerProtocolHandler</tt>.
      *
      * @param httpProcessor HTTP protocol processor.
      * @param handlerMapper Request handler mapper.
      *
      * @since 4.3
      */
     public HttpAsyncService(
             final HttpProcessor httpProcessor,
             final HttpAsyncRequestHandlerMapper handlerMapper) {
         this(httpProcessor, null, null, handlerMapper, null);
     }
 
     public void connected(final NHttpServerConnection conn) {
         final State state = new State();
         conn.getContext().setAttribute(HTTP_EXCHANGE_STATE, state);
     }
 
     public void closed(final NHttpServerConnection conn) {
         final State state = getState(conn);
         if (state != null) {
             state.setTerminated();
             closeHandlers(state);
             final Cancellable cancellable = state.getCancellable();
             if (cancellable != null) {
                 cancellable.cancel();
             }
             state.reset();
         }
     }
 
     public void exception(
             final NHttpServerConnection conn, final Exception cause) {
         final State state = ensureNotNull(getState(conn));
         if (state != null) {
             state.setTerminated();
             closeHandlers(state, cause);
             final Cancellable cancellable = state.getCancellable();
             if (cancellable != null) {
                 cancellable.cancel();
             }
             if (cause instanceof HttpException) {
                 if (conn.isResponseSubmitted()
                         || state.getResponseState().compareTo(MessageState.INIT) > 0) {
                     // There is not much that we can do if a response
                     // has already been submitted
                     closeConnection(conn);
                     log(cause);
                 } else {
                     final HttpContext context = state.getContext();
                     final HttpAsyncResponseProducer responseProducer = handleException(
                             cause, context);
                     state.setResponseProducer(responseProducer);
                     try {
                         final HttpResponse response = responseProducer.generateResponse();
                         state.setResponse(response);
                         commitFinalResponse(conn, state);
                     } catch (final Exception ex) {
                         shutdownConnection(conn);
                         closeHandlers(state);
                         if (ex instanceof RuntimeException) {
                             throw (RuntimeException) ex;
                         } else {
                             log(ex);
                         }
                     }
                 }
             } else {
                 shutdownConnection(conn);
             }
         } else {
             shutdownConnection(conn);
             log(cause);
         }
     }
 
     public void requestReceived(
             final NHttpServerConnection conn) throws IOException, HttpException {
         final State state = ensureNotNull(getState(conn));
         if (state.getResponseState() != MessageState.READY) {
             throw new ProtocolException("Out of sequence request message detected (pipelining is not supported)");
         }
         final HttpRequest request = conn.getHttpRequest();
         final HttpContext context = state.getContext();
 
         context.setAttribute(ExecutionContext.HTTP_REQUEST, request);
         context.setAttribute(ExecutionContext.HTTP_CONNECTION, conn);
         this.httpProcessor.process(request, context);
 
         state.setRequest(request);
         final HttpAsyncRequestHandler<Object> requestHandler = getRequestHandler(request);
         state.setRequestHandler(requestHandler);
         final HttpAsyncRequestConsumer<Object> consumer = requestHandler.processRequest(request, context);
         state.setRequestConsumer(consumer);
 
         consumer.requestReceived(request);
 
         if (request instanceof HttpEntityEnclosingRequest) {
             if (((HttpEntityEnclosingRequest) request).expectContinue()) {
                 state.setRequestState(MessageState.ACK_EXPECTED);
                 final HttpResponse ack = this.responseFactory.newHttpResponse(HttpVersion.HTTP_1_1,
                         HttpStatus.SC_CONTINUE, context);
                 if (this.expectationVerifier != null) {
                     conn.suspendInput();
                     final HttpAsyncExchange httpex = new Exchange(
                             request, ack, state, conn);
                     this.expectationVerifier.verify(httpex, context);
                 } else {
                     conn.submitResponse(ack);
                     state.setRequestState(MessageState.BODY_STREAM);
                 }
             } else {
                 state.setRequestState(MessageState.BODY_STREAM);
             }
         } else {
             // No request content is expected.
             // Process request right away
             processRequest(conn, state);
         }
     }
 
     public void inputReady(
             final NHttpServerConnection conn,
             final ContentDecoder decoder) throws IOException, HttpException {
         final State state = ensureNotNull(getState(conn));
         final HttpAsyncRequestConsumer<?> consumer = ensureNotNull(state.getRequestConsumer());
         consumer.consumeContent(decoder, conn);
         state.setRequestState(MessageState.BODY_STREAM);
         if (decoder.isCompleted()) {
             processRequest(conn, state);
         }
     }
 
     public void responseReady(
             final NHttpServerConnection conn) throws IOException, HttpException {
         final State state = ensureNotNull(getState(conn));
         if (state.getResponse() != null) {
             return;
         }
         final HttpAsyncResponseProducer responseProducer = state.getResponseProducer();
         if (responseProducer == null) {
             return;
         }
         final HttpContext context = state.getContext();
         final HttpResponse response = responseProducer.generateResponse();
         final int status = response.getStatusLine().getStatusCode();
         if (state.getRequestState() == MessageState.ACK_EXPECTED) {
             if (status == 100) {
                 try {
                     // Make sure 100 response has no entity
                     response.setEntity(null);
                     conn.requestInput();
                     state.setRequestState(MessageState.BODY_STREAM);
                     conn.submitResponse(response);
                     responseProducer.responseCompleted(context);
                 } finally {
                     state.setResponseProducer(null);
                     responseProducer.close();
                 }
             } else if (status >= 400) {
                 conn.resetInput();
                 state.setRequestState(MessageState.COMPLETED);
                 state.setResponse(response);
                 commitFinalResponse(conn, state);
             } else {
                 throw new HttpException("Invalid response: " + response.getStatusLine());
             }
         } else {
             if (status >= 200) {
                 state.setResponse(response);
                 commitFinalResponse(conn, state);
             } else {
                 throw new HttpException("Invalid response: " + response.getStatusLine());
             }
         }
     }
 
     public void outputReady(
             final NHttpServerConnection conn,
             final ContentEncoder encoder) throws IOException {
         final State state = ensureNotNull(getState(conn));
         final HttpAsyncResponseProducer responseProducer = state.getResponseProducer();
         final HttpContext context = state.getContext();
         final HttpResponse response = state.getResponse();
 
         responseProducer.produceContent(encoder, conn);
         state.setResponseState(MessageState.BODY_STREAM);
         if (encoder.isCompleted()) {
             responseProducer.responseCompleted(context);
             if (!this.connStrategy.keepAlive(response, context)) {
                 conn.close();
             } else {
                 conn.requestInput();
             }
             closeHandlers(state);
             state.reset();
         }
     }
 
     public void endOfInput(final NHttpServerConnection conn) throws IOException {
         // Closing connection in an orderly manner and
         // waiting for output buffer to get flushed.
         // Do not want to wait indefinitely, though, in case
         // the opposite end is not reading
         if (conn.getSocketTimeout() <= 0) {
             conn.setSocketTimeout(1000);
         }
         conn.close();
     }
 
     public void timeout(final NHttpServerConnection conn) throws IOException {
         final State state = getState(conn);
         if (state != null) {
             closeHandlers(state, new SocketTimeoutException());
         }
         if (conn.getStatus() == NHttpConnection.ACTIVE) {
             conn.close();
             if (conn.getStatus() == NHttpConnection.CLOSING) {
                 // Give the connection some grace time to
                 // close itself nicely
                 conn.setSocketTimeout(250);
             }
         } else {
             conn.shutdown();
         }
     }
 
     private State getState(final NHttpConnection conn) {
         return (State) conn.getContext().getAttribute(HTTP_EXCHANGE_STATE);
     }
 
     private State ensureNotNull(final State state) {
         Asserts.notNull(state, "HTTP exchange state");
         return state;
     }
 
     private HttpAsyncRequestConsumer<Object> ensureNotNull(final HttpAsyncRequestConsumer<Object> requestConsumer) {
         Asserts.notNull(requestConsumer, "Request consumer");
         return requestConsumer;
     }
 
     /**
      * This method can be used to log I/O exception thrown while closing {@link Closeable}
      * objects (such as {@link HttpConnection}).
      *
      * @param ex I/O exception thrown by {@link Closeable#close()}
      */
     protected void log(final Exception ex) {
     }
 
     private void closeConnection(final NHttpConnection conn) {
         try {
             conn.close();
         } catch (final IOException ex) {
             log(ex);
         }
     }
 
     private void shutdownConnection(final NHttpConnection conn) {
         try {
             conn.shutdown();
         } catch (final IOException ex) {
             log(ex);
         }
     }
 
     private void closeHandlers(final State state, final Exception ex) {
         final HttpAsyncRequestConsumer<Object> consumer = state.getRequestConsumer();
         if (consumer != null) {
             try {
                 consumer.failed(ex);
             } finally {
                 try {
                     consumer.close();
                 } catch (final IOException ioex) {
                     log(ioex);
                 }
             }
         }
         final HttpAsyncResponseProducer producer = state.getResponseProducer();
         if (producer != null) {
             try {
                 producer.failed(ex);
             } finally {
                 try {
                     producer.close();
                 } catch (final IOException ioex) {
                     log(ioex);
                 }
             }
         }
     }
 
     private void closeHandlers(final State state) {
         final HttpAsyncRequestConsumer<Object> consumer = state.getRequestConsumer();
         if (consumer != null) {
             try {
                 consumer.close();
             } catch (final IOException ioex) {
                 log(ioex);
             }
         }
         final HttpAsyncResponseProducer producer = state.getResponseProducer();
         if (producer != null) {
             try {
                 producer.close();
             } catch (final IOException ioex) {
                 log(ioex);
             }
         }
     }
 
     protected HttpAsyncResponseProducer handleException(
             final Exception ex, final HttpContext context) {
         int code = HttpStatus.SC_INTERNAL_SERVER_ERROR;
         if (ex instanceof MethodNotSupportedException) {
             code = HttpStatus.SC_NOT_IMPLEMENTED;
         } else if (ex instanceof UnsupportedHttpVersionException) {
             code = HttpStatus.SC_HTTP_VERSION_NOT_SUPPORTED;
         } else if (ex instanceof ProtocolException) {
             code = HttpStatus.SC_BAD_REQUEST;
         }
         String message = ex.getMessage();
         if (message == null) {
             message = ex.toString();
         }
         final HttpResponse response = this.responseFactory.newHttpResponse(HttpVersion.HTTP_1_1,
                 code, context);
         return new ErrorResponseProducer(response,
                 new NStringEntity(message, ContentType.DEFAULT_TEXT), false);
     }
 
     private boolean canResponseHaveBody(final HttpRequest request, final HttpResponse response) {
         if (request != null && "HEAD".equalsIgnoreCase(request.getRequestLine().getMethod())) {
             return false;
         }
         final int status = response.getStatusLine().getStatusCode();
         return status >= HttpStatus.SC_OK
             && status != HttpStatus.SC_NO_CONTENT
             && status != HttpStatus.SC_NOT_MODIFIED
             && status != HttpStatus.SC_RESET_CONTENT;
     }
 
     private void processRequest(
             final NHttpServerConnection conn,
             final State state) throws HttpException, IOException {
         final HttpAsyncRequestHandler<Object> handler = state.getRequestHandler();
         final HttpContext context = state.getContext();
         final HttpAsyncRequestConsumer<?> consumer = state.getRequestConsumer();
         consumer.requestCompleted(context);
         state.setRequestState(MessageState.COMPLETED);
         state.setResponseState(MessageState.INIT);
         final Exception exception = consumer.getException();
         if (exception != null) {
             final HttpAsyncResponseProducer responseProducer = handleException(exception, context);
             state.setResponseProducer(responseProducer);
             conn.requestOutput();
         } else {
             final HttpRequest request = state.getRequest();
             final Object result = consumer.getResult();
             final HttpResponse response = this.responseFactory.newHttpResponse(HttpVersion.HTTP_1_1,
                     HttpStatus.SC_OK, context);
             final Exchange httpexchange = new Exchange(request, response, state, conn);
             try {
                 handler.handle(result, httpexchange, context);
             } catch (final HttpException ex) {
                 final HttpAsyncResponseProducer responseProducer = handleException(ex, context);
                 state.setResponseProducer(responseProducer);
                 conn.requestOutput();
             }
         }
     }
 
     private void commitFinalResponse(
             final NHttpServerConnection conn,
             final State state) throws IOException, HttpException {
         final HttpContext context = state.getContext();
         final HttpRequest request = state.getRequest();
         final HttpResponse response = state.getResponse();
 
         context.setAttribute(ExecutionContext.HTTP_RESPONSE, response);
         this.httpProcessor.process(response, context);
 
         HttpEntity entity = response.getEntity();
         if (entity != null && !canResponseHaveBody(request, response)) {
             response.setEntity(null);
             entity = null;
         }
 
         conn.submitResponse(response);
 
         if (entity == null) {
             final HttpAsyncResponseProducer responseProducer = state.getResponseProducer();
             responseProducer.responseCompleted(context);
             if (!this.connStrategy.keepAlive(response, context)) {
                 conn.close();
             } else {
                 // Ready to process new request
                 conn.requestInput();
             }
             closeHandlers(state);
             state.reset();
         } else {
             state.setResponseState(MessageState.BODY_STREAM);
         }
     }
 
     @SuppressWarnings("unchecked")
     private HttpAsyncRequestHandler<Object> getRequestHandler(final HttpRequest request) {
         HttpAsyncRequestHandler<Object> handler = null;
         if (this.handlerMapper != null) {
             handler = (HttpAsyncRequestHandler<Object>) this.handlerMapper.lookup(request);
         }
         if (handler == null) {
             handler = new NullRequestHandler();
         }
         return handler;
     }
 
     static class State {
 
         private final BasicHttpContext context;
         private volatile boolean terminated;
         private volatile HttpAsyncRequestHandler<Object> requestHandler;
         private volatile MessageState requestState;
         private volatile MessageState responseState;
         private volatile HttpAsyncRequestConsumer<Object> requestConsumer;
         private volatile HttpAsyncResponseProducer responseProducer;
         private volatile HttpRequest request;
         private volatile HttpResponse response;
         private volatile Cancellable cancellable;
 
         State() {
             super();
             this.context = new BasicHttpContext();
             this.requestState = MessageState.READY;
             this.responseState = MessageState.READY;
         }
 
         public HttpContext getContext() {
             return this.context;
         }
 
         public boolean isTerminated() {
             return this.terminated;
         }
 
         public void setTerminated() {
             this.terminated = true;
         }
 
         public HttpAsyncRequestHandler<Object> getRequestHandler() {
             return this.requestHandler;
         }
 
         public void setRequestHandler(final HttpAsyncRequestHandler<Object> requestHandler) {
             this.requestHandler = requestHandler;
         }
 
         public MessageState getRequestState() {
             return this.requestState;
         }
 
         public void setRequestState(final MessageState state) {
             this.requestState = state;
         }
 
         public MessageState getResponseState() {
             return this.responseState;
         }
 
         public void setResponseState(final MessageState state) {
             this.responseState = state;
         }
 
         public HttpAsyncRequestConsumer<Object> getRequestConsumer() {
             return this.requestConsumer;
         }
 
         public void setRequestConsumer(final HttpAsyncRequestConsumer<Object> requestConsumer) {
             this.requestConsumer = requestConsumer;
         }
 
         public HttpAsyncResponseProducer getResponseProducer() {
             return this.responseProducer;
         }
 
         public void setResponseProducer(final HttpAsyncResponseProducer responseProducer) {
             this.responseProducer = responseProducer;
         }
 
         public HttpRequest getRequest() {
             return this.request;
         }
 
         public void setRequest(final HttpRequest request) {
             this.request = request;
         }
 
         public HttpResponse getResponse() {
             return this.response;
         }
 
         public void setResponse(final HttpResponse response) {
             this.response = response;
         }
 
         public Cancellable getCancellable() {
             return this.cancellable;
         }
 
         public void setCancellable(final Cancellable cancellable) {
             this.cancellable = cancellable;
         }
 
         public void reset() {
             this.context.clear();
             this.responseState = MessageState.READY;
             this.requestState = MessageState.READY;
             this.requestHandler = null;
             this.requestConsumer = null;
             this.responseProducer = null;
             this.request = null;
             this.response = null;
             this.cancellable = null;
         }
 
         @Override
         public String toString() {
             final StringBuilder buf = new StringBuilder();
             buf.append("request state: ");
             buf.append(this.requestState);
             buf.append("; request: ");
             if (this.request != null) {
                 buf.append(this.request.getRequestLine());
             }
             buf.append("; response state: ");
             buf.append(this.responseState);
             buf.append("; response: ");
             if (this.response != null) {
                 buf.append(this.response.getStatusLine());
             }
             buf.append(";");
             return buf.toString();
         }
 
     }
 
     static class Exchange implements HttpAsyncExchange {
 
         private final HttpRequest request;
         private final HttpResponse response;
         private final State state;
         private final NHttpServerConnection conn;
 
         private volatile boolean completed;
 
         public Exchange(
                 final HttpRequest request,
                 final HttpResponse response,
                 final State state,
                 final NHttpServerConnection conn) {
             super();
             this.request = request;
             this.response = response;
             this.state = state;
             this.conn = conn;
         }
 
         public HttpRequest getRequest() {
             return this.request;
         }
 
         public HttpResponse getResponse() {
             return this.response;
         }
 
         public void setCallback(final Cancellable cancellable) {
             synchronized (this) {
                 Asserts.check(!this.completed, "Response already submitted");
                 if (this.state.isTerminated() && cancellable != null) {
                     cancellable.cancel();
                 } else {
                     this.state.setCancellable(cancellable);
                     this.conn.requestInput();
                 }
             }
         }
 
         public void submitResponse(final HttpAsyncResponseProducer responseProducer) {
             Args.notNull(responseProducer, "Response producer");
             synchronized (this) {
                 Asserts.check(!this.completed, "Response already submitted");
                 this.completed = true;
                 if (!this.state.isTerminated()) {
                     this.state.setResponseProducer(responseProducer);
                     this.state.setCancellable(null);
                     this.conn.requestOutput();
                 } else {
                     try {
                         responseProducer.close();
                     } catch (final IOException ex) {
                     }
                 }
             }
         }
 
         public void submitResponse() {
             submitResponse(new BasicAsyncResponseProducer(this.response));
         }
 
         public boolean isCompleted() {
             return this.completed;
         }
 
         public void setTimeout(final int timeout) {
             this.conn.setSocketTimeout(timeout);
         }
 
         public int getTimeout() {
             return this.conn.getSocketTimeout();
         }
 
     }
 
     /**
      * Adaptor class to transition from HttpAsyncRequestHandlerResolver to HttpAsyncRequestHandlerMapper.
      */
     @Deprecated
     private static class HttpAsyncRequestHandlerResolverAdapter implements HttpAsyncRequestHandlerMapper {
 
         private final HttpAsyncRequestHandlerResolver resolver;
 
         public HttpAsyncRequestHandlerResolverAdapter(final HttpAsyncRequestHandlerResolver resolver) {
             this.resolver = resolver;
         }
 
         public HttpAsyncRequestHandler<?> lookup(final HttpRequest request) {
             return resolver.lookup(request.getRequestLine().getUri());
         }
 
     }
 
 }