/*
    * ====================================================================
    * 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.IOException;
  import java.net.SocketException;
  import java.net.SocketTimeoutException;
  import java.util.Queue;
  import java.util.concurrent.ConcurrentLinkedQueue;
  import java.util.concurrent.atomic.AtomicBoolean;
  
  import org.apache.http.ConnectionReuseStrategy;
  import org.apache.http.ExceptionLogger;
  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.Contract;
  import org.apache.http.annotation.ThreadingBehavior;
  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.nio.reactor.SessionBufferStatus;
  import org.apache.http.params.HttpParams;
  import org.apache.http.protocol.BasicHttpContext;
  import org.apache.http.protocol.HttpContext;
  import org.apache.http.protocol.HttpCoreContext;
  import org.apache.http.protocol.HttpProcessor;
  import org.apache.http.util.Args;
  import org.apache.http.util.Asserts;
  
  /**
   * {@code HttpAsyncService} is a fully asynchronous HTTP server side protocol
   * handler based on the non-blocking (NIO) I/O model.
   * {@code HttpAsyncServerProtocolHandler} translates individual events fired
   * through the {@link NHttpServerEventHandler} interface into logically related
   * HTTP message exchanges.
   * <p>
   * Upon receiving an incoming request {@code HttpAsyncService} 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>
   * {@code HttpAsyncService} 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")
 @Contract(threading = ThreadingBehavior.IMMUTABLE_CONDITIONAL)
 public class HttpAsyncService implements NHttpServerEventHandler {
 
     static final String HTTP_EXCHANGE_STATE = "http.nio.http-exchange-state";
 
     private final HttpProcessor httpProcessor;
     private final ConnectionReuseStrategy connectionStrategy;
     private final HttpResponseFactory responseFactory;
     private final HttpAsyncRequestHandlerMapper handlerMapper;
     private final HttpAsyncExpectationVerifier expectationVerifier;
     private final ExceptionLogger exceptionLogger;
 
     /**
      * Creates new instance of {@code HttpAsyncServerProtocolHandler}.
      *
      * @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 {@code HttpAsyncServerProtocolHandler}.
      *
      * @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 {@code HttpAsyncServerProtocolHandler}.
      *
      * @param httpProcessor HTTP protocol processor.
      * @param connStrategy Connection re-use strategy. If {@code null}
      *   {@link DefaultConnectionReuseStrategy#INSTANCE} will be used.
      * @param responseFactory HTTP response factory. If {@code null}
      *   {@link DefaultHttpResponseFactory#INSTANCE} will be used.
      * @param handlerMapper Request handler mapper.
      * @param expectationVerifier Request expectation verifier. May be {@code null}.
      *
      * @since 4.3
      */
     public HttpAsyncService(
             final HttpProcessor httpProcessor,
             final ConnectionReuseStrategy connStrategy,
             final HttpResponseFactory responseFactory,
             final HttpAsyncRequestHandlerMapper handlerMapper,
             final HttpAsyncExpectationVerifier expectationVerifier) {
         this(httpProcessor, connStrategy, responseFactory, handlerMapper, expectationVerifier, null);
     }
 
     /**
      * Creates new instance of {@code HttpAsyncServerProtocolHandler}.
      *
      * @param httpProcessor HTTP protocol processor.
      * @param connStrategy Connection re-use strategy. If {@code null}
      *   {@link DefaultConnectionReuseStrategy#INSTANCE} will be used.
      * @param responseFactory HTTP response factory. If {@code null}
      *   {@link DefaultHttpResponseFactory#INSTANCE} will be used.
      * @param handlerMapper Request handler mapper.
      * @param expectationVerifier Request expectation verifier. May be {@code null}.
      * @param exceptionLogger Exception logger. If {@code null}
      *   {@link ExceptionLogger#NO_OP} will be used. Please note that the exception
      *   logger will be only used to log I/O exception thrown while closing
      *   {@link java.io.Closeable} objects (such as {@link org.apache.http.HttpConnection}).
      *
      * @since 4.4
      */
     public HttpAsyncService(
             final HttpProcessor httpProcessor,
             final ConnectionReuseStrategy connStrategy,
             final HttpResponseFactory responseFactory,
             final HttpAsyncRequestHandlerMapper handlerMapper,
             final HttpAsyncExpectationVerifier expectationVerifier,
             final ExceptionLogger exceptionLogger) {
         super();
         this.httpProcessor = Args.notNull(httpProcessor, "HTTP processor");
         this.connectionStrategy = connStrategy != null ? connStrategy :
                 DefaultConnectionReuseStrategy.INSTANCE;
         this.responseFactory = responseFactory != null ? responseFactory :
                 DefaultHttpResponseFactory.INSTANCE;
         this.handlerMapper = handlerMapper;
         this.expectationVerifier = expectationVerifier;
         this.exceptionLogger = exceptionLogger != null ? exceptionLogger : ExceptionLogger.NO_OP;
     }
 
     /**
      * Creates new instance of {@code HttpAsyncServerProtocolHandler}.
      *
      * @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);
     }
 
     /**
      * Creates new instance of {@code HttpAsyncServerProtocolHandler}.
      *
      * @param httpProcessor HTTP protocol processor.
      * @param handlerMapper Request handler mapper.
      * @param exceptionLogger Exception logger. If {@code null}
      *   {@link ExceptionLogger#NO_OP} will be used. Please note that the exception
      *   logger will be only used to log I/O exception thrown while closing
      *   {@link java.io.Closeable} objects (such as {@link org.apache.http.HttpConnection}).
      *
      * @since 4.4
      */
     public HttpAsyncService(
             final HttpProcessor httpProcessor,
             final HttpAsyncRequestHandlerMapper handlerMapper,
             final ExceptionLogger exceptionLogger) {
         this(httpProcessor, null, null, handlerMapper, null, exceptionLogger);
     }
 
     @Override
     public void connected(final NHttpServerConnection conn) {
         final State state = new State();
         conn.getContext().setAttribute(HTTP_EXCHANGE_STATE, state);
     }
 
     @Override
     public void closed(final NHttpServerConnection conn) {
         final State state = (State) conn.getContext().removeAttribute(HTTP_EXCHANGE_STATE);
         if (state != null) {
             state.setTerminated();
             closeHandlers(state);
             final Cancellable cancellable = state.getCancellable();
             if (cancellable != null) {
                 cancellable.cancel();
             }
         }
     }
 
     @Override
     public void exception(
             final NHttpServerConnection conn, final Exception cause) {
         log(cause);
         final State state = getState(conn);
         if (state == null) {
             shutdownConnection(conn);
             return;
         }
         state.setTerminated();
         closeHandlers(state, cause);
         try {
             final Cancellable cancellable = state.getCancellable();
             if (cancellable != null) {
                 cancellable.cancel();
             }
             if (cause instanceof SocketException || cause.getClass() == IOException.class) {
                 // Transport layer is likely unreliable.
                 conn.shutdown();
                 return;
             }
             if (cause instanceof SocketTimeoutException) {
                 // Connection timed out due to inactivity.
                 conn.close();
                 return;
             }
 
             if (conn.isResponseSubmitted() || state.getResponseState().compareTo(MessageState.INIT) > 0) {
                 // There is not much that we can do if a response has already been submitted.
                 conn.close();
                 return;
             }
             HttpRequest request = conn.getHttpRequest();
             if (request == null) {
                 final Incoming incoming = state.getIncoming();
                 if (incoming != null) {
                     request = incoming.getRequest();
                 }
             }
             if (request == null) {
                 final Queue<PipelineEntry> pipeline = state.getPipeline();
                 final PipelineEntry pipelineEntry = pipeline.poll();
                 if (pipelineEntry != null) {
                     request = pipelineEntry.getRequest();
                 }
             }
             if (request != null) {
                 conn.resetInput();
                 final HttpCoreContext context = HttpCoreContext.create();
                 final HttpAsyncResponseProducer responseProducer = handleException(cause, context);
                 final HttpResponse response = responseProducer.generateResponse();
                 final Outgoing outgoing = new Outgoing(request, response, responseProducer, context);
                 state.setResponseState(MessageState.INIT);
                 state.setOutgoing(outgoing);
                 commitFinalResponse(conn, state);
                 return;
             }
             conn.close();
         } catch (final Exception ex) {
             shutdownConnection(conn);
             closeHandlers(state);
             if (ex instanceof RuntimeException) {
                 throw (RuntimeException) ex;
             }
             log(ex);
         }
     }
 
     protected HttpResponse createHttpResponse(final int status, final HttpContext context) {
         return this.responseFactory.newHttpResponse(HttpVersion.HTTP_1_1, status, context);
     }
 
     @Override
     public void requestReceived(
             final NHttpServerConnection conn) throws IOException, HttpException {
         final State state = getState(conn);
         Asserts.notNull(state, "Connection state");
         Asserts.check(state.getRequestState() == MessageState.READY,
                 "Unexpected request state %s", state.getRequestState());
 
         final HttpRequest request = conn.getHttpRequest();
         final HttpContext context = new BasicHttpContext();
 
         context.setAttribute(HttpCoreContext.HTTP_REQUEST, request);
         context.setAttribute(HttpCoreContext.HTTP_CONNECTION, conn);
         this.httpProcessor.process(request, context);
 
         final HttpAsyncRequestHandler<Object> requestHandler = getRequestHandler(request);
         final HttpAsyncRequestConsumer<Object> consumer = requestHandler.processRequest(request, context);
         consumer.requestReceived(request);
 
         final Incoming incoming = new Incoming(request, requestHandler, consumer, context);
         state.setIncoming(incoming);
 
         if (request instanceof HttpEntityEnclosingRequest) {
 
             // If 100-continue is expected make sure
             // there is no pending response data, no pipelined requests or buffered input
             if (((HttpEntityEnclosingRequest) request).expectContinue()
                         && state.getResponseState() == MessageState.READY
                         && state.getPipeline().isEmpty()
                         && !(conn instanceof SessionBufferStatusrg/apache/http/nio/reactor/SessionBufferStatus.html#SessionBufferStatus">SessionBufferStatus && ((SessionBufferStatus) conn).hasBufferedInput())) {
 
                 state.setRequestState(MessageState.ACK_EXPECTED);
                 final HttpResponse ack = createHttpResponse(HttpStatus.SC_CONTINUE, context);
                 if (this.expectationVerifier != null) {
                     conn.suspendInput();
                     conn.suspendOutput();
                     final HttpAsyncExchange httpAsyncExchange = new HttpAsyncExchangeImpl(
                             request, ack, state, conn, context);
                     this.expectationVerifier.verify(httpAsyncExchange, 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
             completeRequest(incoming, conn, state);
         }
     }
 
     @Override
     public void inputReady(
             final NHttpServerConnection conn,
             final ContentDecoder decoder) throws IOException, HttpException {
         final State state = getState(conn);
         Asserts.notNull(state, "Connection state");
         Asserts.check(state.getRequestState() == MessageState.BODY_STREAM,
                 "Unexpected request state %s", state.getRequestState());
 
         final Incoming incoming = state.getIncoming();
         Asserts.notNull(incoming, "Incoming request");
         final HttpAsyncRequestConsumer<?> consumer = incoming.getConsumer();
         consumer.consumeContent(decoder, conn);
         if (decoder.isCompleted()) {
             completeRequest(incoming, conn, state);
         }
     }
 
     @Override
     public void responseReady(
             final NHttpServerConnection conn) throws IOException, HttpException {
         final State state = getState(conn);
         Asserts.notNull(state, "Connection state");
         Asserts.check(state.getResponseState() == MessageState.READY ||
                         state.getResponseState() == MessageState.INIT,
                 "Unexpected response state %s", state.getResponseState());
 
         if (state.getRequestState() == MessageState.ACK_EXPECTED) {
             final Outgoing outgoing;
             synchronized (state) {
                 outgoing = state.getOutgoing();
                 if (outgoing == null) {
                     conn.suspendOutput();
                     return;
                 }
             }
             final HttpResponse response = outgoing.getResponse();
             final int status = response.getStatusLine().getStatusCode();
             if (status == 100) {
                 final HttpContext context = outgoing.getContext();
                 final HttpAsyncResponseProducer responseProducer = outgoing.getProducer();
                 try {
                     // Make sure 100 response has no entity
                     response.setEntity(null);
                     conn.requestInput();
                     state.setRequestState(MessageState.BODY_STREAM);
                     state.setOutgoing(null);
                     conn.submitResponse(response);
                     responseProducer.responseCompleted(context);
                 } finally {
                     responseProducer.close();
                 }
             } else if (status >= 400) {
                 conn.resetInput();
                 state.setRequestState(MessageState.READY);
                 commitFinalResponse(conn, state);
             } else {
                 throw new HttpException("Invalid response: " + response.getStatusLine());
             }
         } else {
             if (state.getResponseState() == MessageState.READY) {
                 final Queue<PipelineEntry> pipeline = state.getPipeline();
                 final PipelineEntry pipelineEntry = pipeline.poll();
                 if (pipelineEntry == null) {
                     conn.suspendOutput();
                     return;
                 }
                 state.setResponseState(MessageState.INIT);
                 final Object result = pipelineEntry.getResult();
                 final HttpRequest request = pipelineEntry.getRequest();
                 final HttpContext context = pipelineEntry.getContext();
                 final HttpResponse response = createHttpResponse(HttpStatus.SC_OK, context);
                 final HttpAsyncExchangeImpl httpExchange = new HttpAsyncExchangeImpl(
                         request, response, state, conn, context);
                 if (result != null) {
                     final HttpAsyncRequestHandler<Object> handler = pipelineEntry.getHandler();
                     conn.suspendOutput();
                     try {
                         handler.handle(result, httpExchange, context);
                     } catch (final RuntimeException ex) {
                         throw ex;
                     } catch (final Exception ex) {
                         if (!httpExchange.isCompleted()) {
                             httpExchange.submitResponse(handleException(ex, context));
                         } else {
                             log(ex);
                             conn.close();
                         }
                         return;
                     }
                 } else {
                     final Exception exception = pipelineEntry.getException();
                     final HttpAsyncResponseProducer responseProducer = handleException(
                             exception != null ? exception : new HttpException("Internal error processing request"),
                             context);
                     httpExchange.submitResponse(responseProducer);
                 }
             }
             if (state.getResponseState() == MessageState.INIT) {
                 final Outgoing outgoing;
                 synchronized (state) {
                     outgoing = state.getOutgoing();
                     if (outgoing == null) {
                         conn.suspendOutput();
                         return;
                     }
                 }
                 final HttpResponse response = outgoing.getResponse();
                 final int status = response.getStatusLine().getStatusCode();
                 if (status >= 200) {
                     commitFinalResponse(conn, state);
                 } else {
                     throw new HttpException("Invalid response: " + response.getStatusLine());
                 }
             }
         }
     }
 
     @Override
     public void outputReady(
             final NHttpServerConnection conn,
             final ContentEncoder encoder) throws HttpException, IOException {
         final State state = getState(conn);
         Asserts.notNull(state, "Connection state");
         Asserts.check(state.getResponseState() == MessageState.BODY_STREAM,
                 "Unexpected response state %s", state.getResponseState());
 
         final Outgoing outgoing = state.getOutgoing();
         Asserts.notNull(outgoing, "Outgoing response");
         final HttpAsyncResponseProducer responseProducer = outgoing.getProducer();
 
         responseProducer.produceContent(encoder, conn);
 
         if (encoder.isCompleted()) {
             completeResponse(outgoing, conn, state);
         }
     }
 
     @Override
     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();
     }
 
     @Override
     public void timeout(final NHttpServerConnection conn) throws IOException {
         final State state = getState(conn);
         if (state != null) {
             closeHandlers(state, new SocketTimeoutException(
                     String.format("%,d milliseconds timeout on connection %s", conn.getSocketTimeout(), conn)));
         }
         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);
     }
 
     /**
      * This method can be used to log I/O exception thrown while closing
      * {@link java.io.Closeable} objects (such as
      * {@link org.apache.http.HttpConnection}).
      *
      * @param ex I/O exception thrown by {@link java.io.Closeable#close()}
      */
     protected void log(final Exception ex) {
         this.exceptionLogger.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.getIncoming() != null ? state.getIncoming().getConsumer() : null;
         if (consumer != null) {
             try {
                 consumer.failed(ex);
             } finally {
                 try {
                     consumer.close();
                 } catch (final IOException ioex) {
                     log(ioex);
                 }
             }
         }
         final HttpAsyncResponseProducer producer =
                 state.getOutgoing() != null ? state.getOutgoing().getProducer() : null;
         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.getIncoming() != null ? state.getIncoming().getConsumer() : null;
         if (consumer != null) {
             try {
                 consumer.close();
             } catch (final IOException ioex) {
                 log(ioex);
             }
         }
         final HttpAsyncResponseProducer producer =
                 state.getOutgoing() != null ? state.getOutgoing().getProducer() : null;
         if (producer != null) {
             try {
                 producer.close();
             } catch (final IOException ioex) {
                 log(ioex);
             }
         }
     }
 
     protected HttpAsyncResponseProducer handleException(
             final Exception ex, final HttpContext context) {
         String message = ex.getMessage();
         if (message == null) {
             message = ex.toString();
         }
         final HttpResponse response = createHttpResponse(toStatusCode(ex, context), context);
         return new ErrorResponseProducer(response, new NStringEntity(message, ContentType.DEFAULT_TEXT), false);
     }
 
     protected int toStatusCode(final Exception ex, final HttpContext context) {
         final int code;
         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;
         } else {
             code = HttpStatus.SC_INTERNAL_SERVER_ERROR;
         }
         return code;
     }
 
     /**
      * This method can be used to handle callback set up happened after
      * response submission.
      *
      * @param cancellable Request cancellation callback.
      * @param context Request context.
      *
      * @since 4.4
      */
     protected void handleAlreadySubmittedResponse(
             final Cancellable cancellable, final HttpContext context) {
         throw new IllegalStateException("Response already submitted");
     }
 
     /**
      * This method can be used to handle double response submission.
      *
      * @param responseProducer Response producer for second response.
      * @param context Request context.
      *
      * @since 4.4
      */
     protected void handleAlreadySubmittedResponse(
             final HttpAsyncResponseProducer responseProducer,
             final HttpContext context) {
         throw new IllegalStateException("Response already submitted");
     }
 
     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 completeRequest(
             final Incoming incoming,
             final NHttpServerConnection conn,
             final State state) throws IOException {
         state.setRequestState(MessageState.READY);
         state.setIncoming(null);
 
         final PipelineEntry pipelineEntry;
         final HttpAsyncRequestConsumer<?> consumer = incoming.getConsumer();
         try {
             final HttpContext context = incoming.getContext();
             consumer.requestCompleted(context);
             pipelineEntry = new PipelineEntry(
                     incoming.getRequest(),
                     consumer.getResult(),
                     consumer.getException(),
                     incoming.getHandler(),
                     context);
         } finally {
             consumer.close();
         }
         final Queue<PipelineEntry> pipeline = state.getPipeline();
         pipeline.add(pipelineEntry);
         if (state.getResponseState() == MessageState.READY) {
             conn.requestOutput();
         }
     }
 
     private void commitFinalResponse(
             final NHttpServerConnection conn,
             final State state) throws IOException, HttpException {
         final Outgoing outgoing = state.getOutgoing();
         Asserts.notNull(outgoing, "Outgoing response");
         final HttpRequest request = outgoing.getRequest();
         final HttpResponse response = outgoing.getResponse();
         final HttpContext context = outgoing.getContext();
 
         context.setAttribute(HttpCoreContext.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) {
             completeResponse(outgoing, conn, state);
         } else {
             state.setResponseState(MessageState.BODY_STREAM);
         }
     }
 
     private void completeResponse(
             final Outgoing outgoing,
             final NHttpServerConnection conn,
             final State state) throws IOException {
         final HttpContext context = outgoing.getContext();
         final HttpResponse response = outgoing.getResponse();
         final HttpAsyncResponseProducer responseProducer = outgoing.getProducer();
         try {
             responseProducer.responseCompleted(context);
             state.setOutgoing(null);
             state.setCancellable(null);
             state.setResponseState(MessageState.READY);
         } finally {
             responseProducer.close();
         }
         if (!this.connectionStrategy.keepAlive(response, context)) {
             conn.close();
         } else {
             conn.requestInput();
         }
     }
 
     @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 = NullRequestHandler.INSTANCE;
         }
         return handler;
     }
 
     static class Incoming {
 
         private final HttpRequest request;
         private final HttpAsyncRequestHandler<Object> handler;
         private final HttpAsyncRequestConsumer<Object> consumer;
         private final HttpContext context;
 
         Incoming(
                 final HttpRequest request,
                 final HttpAsyncRequestHandler<Object> handler,
                 final HttpAsyncRequestConsumer<Object> consumer,
                 final HttpContext context) {
             this.request = request;
             this.handler = handler;
             this.consumer = consumer;
             this.context = context;
         }
 
         public HttpRequest getRequest() {
             return this.request;
         }
 
         public HttpAsyncRequestHandler<Object> getHandler() {
             return this.handler;
         }
 
         public HttpAsyncRequestConsumer<Object> getConsumer() {
             return this.consumer;
         }
 
         public HttpContext getContext() {
             return this.context;
         }
     }
 
     static class Outgoing {
 
         private final HttpRequest request;
         private final HttpResponse response;
         private final HttpAsyncResponseProducer producer;
         private final HttpContext context;
 
         Outgoing(
                 final HttpRequest request,
                 final HttpResponse response,
                 final HttpAsyncResponseProducer producer,
                 final HttpContext context) {
             this.request = request;
             this.response = response;
             this.producer = producer;
             this.context = context;
         }
 
         public HttpRequest getRequest() {
             return this.request;
         }
 
         public HttpResponse getResponse() {
             return this.response;
         }
 
         public HttpAsyncResponseProducer getProducer() {
             return this.producer;
         }
 
         public HttpContext getContext() {
             return this.context;
         }
     }
 
     static class PipelineEntry {
 
         private final HttpRequest request;
         private final Object result;
         private final Exception exception;
         private final HttpAsyncRequestHandler<Object> handler;
         private final HttpContext context;
 
         PipelineEntry(
                 final HttpRequest request,
                 final Object result,
                 final Exception exception,
                 final HttpAsyncRequestHandler<Object> handler,
                 final HttpContext context) {
             this.request = request;
             this.result = result;
             this.exception = exception;
             this.handler = handler;
             this.context = context;
         }
 
         public HttpRequest getRequest() {
             return this.request;
         }
 
         public Object getResult() {
             return this.result;
         }
 
         public Exception getException() {
             return this.exception;
         }
 
         public HttpAsyncRequestHandler<Object> getHandler() {
             return this.handler;
         }
 
         public HttpContext getContext() {
             return this.context;
         }
 
     }
 
     static class State {
 
         private final Queue<PipelineEntry> pipeline;
         private volatile boolean terminated;
         private volatile MessageState requestState;
         private volatile MessageState responseState;
         private volatile Incoming incoming;
         private volatile Outgoing outgoing;
         private volatile Cancellable cancellable;
 
         State() {
             super();
             this.pipeline = new ConcurrentLinkedQueue<PipelineEntry>();
             this.requestState = MessageState.READY;
             this.responseState = MessageState.READY;
         }
 
         public boolean isTerminated() {
             return this.terminated;
         }
 
         public void setTerminated() {
             this.terminated = true;
         }
 
         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 Incoming getIncoming() {
             return this.incoming;
         }
 
         public void setIncoming(final Incoming incoming) {
             this.incoming = incoming;
         }
 
         public Outgoing getOutgoing() {
             return this.outgoing;
         }
 
         public void setOutgoing(final Outgoing outgoing) {
             this.outgoing = outgoing;
         }
 
         public Cancellable getCancellable() {
             return this.cancellable;
         }
 
         public void setCancellable(final Cancellable cancellable) {
             this.cancellable = cancellable;
         }
 
         public Queue<PipelineEntry> getPipeline() {
             return this.pipeline;
         }
 
         @Override
         public String toString() {
             final StringBuilder buf = new StringBuilder();
             buf.append("[incoming ");
             buf.append(this.requestState);
             if (this.incoming != null) {
                 buf.append(" ");
                 buf.append(this.incoming.getRequest().getRequestLine());
             }
             buf.append("; outgoing ");
             buf.append(this.responseState);
             if (this.outgoing != null) {
                 buf.append(" ");
                 buf.append(this.outgoing.getResponse().getStatusLine());
             }
             buf.append("]");
             return buf.toString();
         }
 
     }
 
     class HttpAsyncExchangeImpl implements HttpAsyncExchange {
 
         private final AtomicBoolean completed = new AtomicBoolean();
         private final HttpRequest request;
         private final HttpResponse response;
         private final State state;
         private final NHttpServerConnection conn;
         private final HttpContext context;
 
         public HttpAsyncExchangeImpl(
                 final HttpRequest request,
                 final HttpResponse response,
                 final State state,
                 final NHttpServerConnection conn,
                 final HttpContext context) {
             super();
             this.request = request;
             this.response = response;
             this.state = state;
             this.conn = conn;
             this.context = context;
         }
 
         @Override
         public HttpRequest getRequest() {
             return this.request;
         }
 
         @Override
         public HttpResponse getResponse() {
             return this.response;
         }
 
         @Override
         public void setCallback(final Cancellable cancellable) {
             if (this.completed.get()) {
                 handleAlreadySubmittedResponse(cancellable, context);
             } else if (this.state.isTerminated() && cancellable != null) {
                 cancellable.cancel();
             } else {
                 this.state.setCancellable(cancellable);
             }
         }
 
         @Override
         public void submitResponse(final HttpAsyncResponseProducer responseProducer) {
             Args.notNull(responseProducer, "Response producer");
             if (this.completed.getAndSet(true)) {
                 handleAlreadySubmittedResponse(responseProducer, context);
             } else if (!this.state.isTerminated()) {
                 final HttpResponse response = responseProducer.generateResponse();
                 final Outgoing outgoing = new Outgoing(
                         this.request, response, responseProducer, this.context);
 
                 synchronized (this.state) {
                     this.state.setOutgoing(outgoing);
                     this.state.setCancellable(null);
                     this.conn.requestOutput();
                 }
 
             } else {
                 try {
                     responseProducer.close();
                 } catch (final IOException ex) {
                     log(ex);
                 }
             }
         }
 
         @Override
         public void submitResponse() {
             submitResponse(new BasicAsyncResponseProducer(this.response));
         }
 
         @Override
         public boolean isCompleted() {
             return this.completed.get();
         }
 
         @Override
         public void setTimeout(final int timeout) {
             this.conn.setSocketTimeout(timeout);
         }
 
         @Override
         public int getTimeout() {
             return this.conn.getSocketTimeout();
         }
 
     }
 
     /**
      * Adaptor class to transition from HttpAsyncRequestHandlerResolver to HttpAsyncRequestHandlerMapper.
      *
      * @deprecated Do not use.
      */
     @Deprecated
     private static class HttpAsyncRequestHandlerResolverAdapter implements HttpAsyncRequestHandlerMapper {
 
         private final HttpAsyncRequestHandlerResolver resolver;
 
         public HttpAsyncRequestHandlerResolverAdapter(final HttpAsyncRequestHandlerResolver resolver) {
             this.resolver = resolver;
         }
 
         @Override
         public HttpAsyncRequestHandler<?> lookup(final HttpRequest request) {
             return resolver.lookup(request.getRequestLine().getUri());
         }
 
     }
 
     /**
      * Gets the HttpResponseFactory for this service.
      *
      * @return  the HttpResponseFactory for this service.
      * @since 4.4.8
      */
     public HttpResponseFactory getResponseFactory() {
       return responseFactory;
     }
 
     /**
      * Gets the HttpProcessor for this service.
      *
      * @return the HttpProcessor for this service.
      * @since 4.4.9
      */
     public HttpProcessor getHttpProcessor() {
         return httpProcessor;
     }
 
     /**
      * Gets the ConnectionReuseStrategy for this service.
      *
      * @return the ConnectionReuseStrategy for this service.
      * @since 4.4.9
      */
     public ConnectionReuseStrategy getConnectionStrategy() {
         return connectionStrategy;
     }
 
     /**
      * Gets the HttpAsyncRequestHandlerMapper for this service.
      *
      * @return the HttpAsyncRequestHandlerMapper for this service.
      * @since 4.4.9
      */
     public HttpAsyncRequestHandlerMapper getHandlerMapper() {
         return handlerMapper;
     }
 
     /**
      * Gets the HttpAsyncExpectationVerifier for this service.
      *
      * @return the HttpAsyncExpectationVerifier for this service.
      * @since 4.4.9
      */
     public HttpAsyncExpectationVerifier getExpectationVerifier() {
         return expectationVerifier;
     }
 
     /**
      * Gets the ExceptionLogger for this service.
      *
      * @return the ExceptionLogger for this service.
      * @since 4.4.9
      */
     public ExceptionLogger getExceptionLogger() {
         return exceptionLogger;
     }
 
 }