View Javadoc
1   /*
2    * ====================================================================
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *   http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing,
14   * software distributed under the License is distributed on an
15   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16   * KIND, either express or implied.  See the License for the
17   * specific language governing permissions and limitations
18   * under the License.
19   * ====================================================================
20   *
21   * This software consists of voluntary contributions made by many
22   * individuals on behalf of the Apache Software Foundation.  For more
23   * information on the Apache Software Foundation, please see
24   * <http://www.apache.org/>.
25   *
26   */
27  
28  package org.apache.http.nio.protocol;
29  
30  import java.io.IOException;
31  import java.net.SocketTimeoutException;
32  import java.util.Queue;
33  import java.util.concurrent.ConcurrentLinkedQueue;
34  import java.util.concurrent.atomic.AtomicBoolean;
35  
36  import org.apache.http.ConnectionReuseStrategy;
37  import org.apache.http.ExceptionLogger;
38  import org.apache.http.HttpEntity;
39  import org.apache.http.HttpEntityEnclosingRequest;
40  import org.apache.http.HttpException;
41  import org.apache.http.HttpRequest;
42  import org.apache.http.HttpResponse;
43  import org.apache.http.HttpResponseFactory;
44  import org.apache.http.HttpStatus;
45  import org.apache.http.HttpVersion;
46  import org.apache.http.MethodNotSupportedException;
47  import org.apache.http.ProtocolException;
48  import org.apache.http.UnsupportedHttpVersionException;
49  import org.apache.http.annotation.Contract;
50  import org.apache.http.annotation.ThreadingBehavior;
51  import org.apache.http.concurrent.Cancellable;
52  import org.apache.http.entity.ContentType;
53  import org.apache.http.impl.DefaultConnectionReuseStrategy;
54  import org.apache.http.impl.DefaultHttpResponseFactory;
55  import org.apache.http.nio.ContentDecoder;
56  import org.apache.http.nio.ContentEncoder;
57  import org.apache.http.nio.NHttpConnection;
58  import org.apache.http.nio.NHttpServerConnection;
59  import org.apache.http.nio.NHttpServerEventHandler;
60  import org.apache.http.nio.entity.NStringEntity;
61  import org.apache.http.nio.reactor.SessionBufferStatus;
62  import org.apache.http.params.HttpParams;
63  import org.apache.http.protocol.BasicHttpContext;
64  import org.apache.http.protocol.HttpContext;
65  import org.apache.http.protocol.HttpCoreContext;
66  import org.apache.http.protocol.HttpProcessor;
67  import org.apache.http.util.Args;
68  import org.apache.http.util.Asserts;
69  
70  /**
71   * {@code HttpAsyncService} is a fully asynchronous HTTP server side protocol
72   * handler based on the non-blocking (NIO) I/O model.
73   * {@code HttpAsyncServerProtocolHandler} translates individual events fired
74   * through the {@link NHttpServerEventHandler} interface into logically related
75   * HTTP message exchanges.
76   * <p>
77   * Upon receiving an incoming request {@code HttpAsyncService} verifies
78   * the message for compliance with the server expectations using
79   * {@link HttpAsyncExpectationVerifier}, if provided, and then
80   * {@link HttpAsyncRequestHandlerMapper} is used to map the request
81   * to a particular {@link HttpAsyncRequestHandler} intended to handle
82   * the request with the given URI. The protocol handler uses the selected
83   * {@link HttpAsyncRequestHandler} instance to process the incoming request
84   * and to generate an outgoing response.
85   * <p>
86   * {@code HttpAsyncService} relies on {@link HttpProcessor} to generate
87   * mandatory protocol headers for all outgoing messages and apply common,
88   * cross-cutting message transformations to all incoming and outgoing messages,
89   * whereas individual {@link HttpAsyncRequestHandler}s are expected
90   * to implement application specific content generation and processing.
91   * <p>
92   * Individual {@link HttpAsyncRequestHandler}s do not have to submit a response
93   * immediately. They can defer transmission of an HTTP response back to
94   * the client without blocking the I/O thread by delegating the process of
95   * request handling to another service or a worker thread. HTTP response can
96   * be submitted as a later a later point of time once response content becomes
97   * available.
98   *
99   * @since 4.2
100  */
101 @SuppressWarnings("deprecation")
102 @Contract(threading = ThreadingBehavior.IMMUTABLE_CONDITIONAL)
103 public class HttpAsyncService implements NHttpServerEventHandler {
104 
105     static final String HTTP_EXCHANGE_STATE = "http.nio.http-exchange-state";
106 
107     private final HttpProcessor httpProcessor;
108     private final ConnectionReuseStrategy connStrategy;
109     private final HttpResponseFactory responseFactory;
110     private final HttpAsyncRequestHandlerMapper handlerMapper;
111     private final HttpAsyncExpectationVerifier expectationVerifier;
112     private final ExceptionLogger exceptionLogger;
113 
114     /**
115      * Creates new instance of {@code HttpAsyncServerProtocolHandler}.
116      *
117      * @param httpProcessor HTTP protocol processor (required).
118      * @param connStrategy Connection re-use strategy (required).
119      * @param responseFactory HTTP response factory (required).
120      * @param handlerResolver Request handler resolver.
121      * @param expectationVerifier Request expectation verifier (optional).
122      * @param params HTTP parameters (required).
123      *
124      * @deprecated (4.3) use {@link HttpAsyncService#HttpAsyncService(HttpProcessor,
125      *  ConnectionReuseStrategy, HttpResponseFactory, HttpAsyncRequestHandlerMapper,
126      *    HttpAsyncExpectationVerifier)}
127      */
128     @Deprecated
129     public HttpAsyncService(
130             final HttpProcessor httpProcessor,
131             final ConnectionReuseStrategy connStrategy,
132             final HttpResponseFactory responseFactory,
133             final HttpAsyncRequestHandlerResolver handlerResolver,
134             final HttpAsyncExpectationVerifier expectationVerifier,
135             final HttpParams params) {
136         this(httpProcessor,
137              connStrategy,
138              responseFactory,
139              new HttpAsyncRequestHandlerResolverAdapter(handlerResolver),
140              expectationVerifier);
141     }
142 
143     /**
144      * Creates new instance of {@code HttpAsyncServerProtocolHandler}.
145      *
146      * @param httpProcessor HTTP protocol processor (required).
147      * @param connStrategy Connection re-use strategy (required).
148      * @param handlerResolver Request handler resolver.
149      * @param params HTTP parameters (required).
150      *
151      * @deprecated (4.3) use {@link HttpAsyncService#HttpAsyncService(HttpProcessor,
152      *   ConnectionReuseStrategy, HttpResponseFactory, HttpAsyncRequestHandlerMapper,
153      *   HttpAsyncExpectationVerifier)}
154      */
155     @Deprecated
156     public HttpAsyncService(
157             final HttpProcessor httpProcessor,
158             final ConnectionReuseStrategy connStrategy,
159             final HttpAsyncRequestHandlerResolver handlerResolver,
160             final HttpParams params) {
161         this(httpProcessor,
162              connStrategy,
163              DefaultHttpResponseFactory.INSTANCE,
164              new HttpAsyncRequestHandlerResolverAdapter(handlerResolver),
165              null);
166     }
167 
168     /**
169      * Creates new instance of {@code HttpAsyncServerProtocolHandler}.
170      *
171      * @param httpProcessor HTTP protocol processor.
172      * @param connStrategy Connection re-use strategy. If {@code null}
173      *   {@link DefaultConnectionReuseStrategy#INSTANCE} will be used.
174      * @param responseFactory HTTP response factory. If {@code null}
175      *   {@link DefaultHttpResponseFactory#INSTANCE} will be used.
176      * @param handlerMapper Request handler mapper.
177      * @param expectationVerifier Request expectation verifier. May be {@code null}.
178      *
179      * @since 4.3
180      */
181     public HttpAsyncService(
182             final HttpProcessor httpProcessor,
183             final ConnectionReuseStrategy connStrategy,
184             final HttpResponseFactory responseFactory,
185             final HttpAsyncRequestHandlerMapper handlerMapper,
186             final HttpAsyncExpectationVerifier expectationVerifier) {
187         this(httpProcessor, connStrategy, responseFactory, handlerMapper, expectationVerifier, null);
188     }
189 
190     /**
191      * Creates new instance of {@code HttpAsyncServerProtocolHandler}.
192      *
193      * @param httpProcessor HTTP protocol processor.
194      * @param connStrategy Connection re-use strategy. If {@code null}
195      *   {@link DefaultConnectionReuseStrategy#INSTANCE} will be used.
196      * @param responseFactory HTTP response factory. If {@code null}
197      *   {@link DefaultHttpResponseFactory#INSTANCE} will be used.
198      * @param handlerMapper Request handler mapper.
199      * @param expectationVerifier Request expectation verifier. May be {@code null}.
200      * @param exceptionLogger Exception logger. If {@code null}
201      *   {@link ExceptionLogger#NO_OP} will be used. Please note that the exception
202      *   logger will be only used to log I/O exception thrown while closing
203      *   {@link java.io.Closeable} objects (such as {@link org.apache.http.HttpConnection}).
204      *
205      * @since 4.4
206      */
207     public HttpAsyncService(
208             final HttpProcessor httpProcessor,
209             final ConnectionReuseStrategy connStrategy,
210             final HttpResponseFactory responseFactory,
211             final HttpAsyncRequestHandlerMapper handlerMapper,
212             final HttpAsyncExpectationVerifier expectationVerifier,
213             final ExceptionLogger exceptionLogger) {
214         super();
215         this.httpProcessor = Args.notNull(httpProcessor, "HTTP processor");
216         this.connStrategy = connStrategy != null ? connStrategy :
217                 DefaultConnectionReuseStrategy.INSTANCE;
218         this.responseFactory = responseFactory != null ? responseFactory :
219                 DefaultHttpResponseFactory.INSTANCE;
220         this.handlerMapper = handlerMapper;
221         this.expectationVerifier = expectationVerifier;
222         this.exceptionLogger = exceptionLogger != null ? exceptionLogger : ExceptionLogger.NO_OP;
223     }
224 
225     /**
226      * Creates new instance of {@code HttpAsyncServerProtocolHandler}.
227      *
228      * @param httpProcessor HTTP protocol processor.
229      * @param handlerMapper Request handler mapper.
230      *
231      * @since 4.3
232      */
233     public HttpAsyncService(
234             final HttpProcessor httpProcessor,
235             final HttpAsyncRequestHandlerMapper handlerMapper) {
236         this(httpProcessor, null, null, handlerMapper, null);
237     }
238 
239     /**
240      * Creates new instance of {@code HttpAsyncServerProtocolHandler}.
241      *
242      * @param httpProcessor HTTP protocol processor.
243      * @param handlerMapper Request handler mapper.
244      * @param exceptionLogger Exception logger. If {@code null}
245      *   {@link ExceptionLogger#NO_OP} will be used. Please note that the exception
246      *   logger will be only used to log I/O exception thrown while closing
247      *   {@link java.io.Closeable} objects (such as {@link org.apache.http.HttpConnection}).
248      *
249      * @since 4.4
250      */
251     public HttpAsyncService(
252             final HttpProcessor httpProcessor,
253             final HttpAsyncRequestHandlerMapper handlerMapper,
254             final ExceptionLogger exceptionLogger) {
255         this(httpProcessor, null, null, handlerMapper, null, exceptionLogger);
256     }
257 
258     @Override
259     public void connected(final NHttpServerConnection conn) {
260         final State state = new State();
261         conn.getContext().setAttribute(HTTP_EXCHANGE_STATE, state);
262     }
263 
264     @Override
265     public void closed(final NHttpServerConnection conn) {
266         final State state = (State) conn.getContext().removeAttribute(HTTP_EXCHANGE_STATE);
267         if (state != null) {
268             state.setTerminated();
269             closeHandlers(state);
270             final Cancellable cancellable = state.getCancellable();
271             if (cancellable != null) {
272                 cancellable.cancel();
273             }
274         }
275     }
276 
277     @Override
278     public void exception(
279             final NHttpServerConnection conn, final Exception cause) {
280         log(cause);
281         final State state = getState(conn);
282         if (state == null) {
283             shutdownConnection(conn);
284             return;
285         }
286         state.setTerminated();
287         closeHandlers(state, cause);
288         final Cancellable cancellable = state.getCancellable();
289         if (cancellable != null) {
290             cancellable.cancel();
291         }
292         final Queue<PipelineEntry> pipeline = state.getPipeline();
293         if (!pipeline.isEmpty()
294                 || conn.isResponseSubmitted()
295                 || state.getResponseState().compareTo(MessageState.INIT) > 0) {
296             // There is not much that we can do if a response
297             // has already been submitted or pipelining is being used.
298             shutdownConnection(conn);
299         } else {
300             try {
301                 final Incoming incoming = state.getIncoming();
302                 final HttpRequest request = incoming != null ? incoming.getRequest() : null;
303                 final HttpContext context = incoming != null ? incoming.getContext() : new BasicHttpContext();
304                 final HttpAsyncResponseProducer responseProducer = handleException(cause, context);
305                 final HttpResponse response = responseProducer.generateResponse();
306                 final Outgoing outgoing = new Outgoing(request, response, responseProducer, context);
307                 state.setResponseState(MessageState.INIT);
308                 state.setOutgoing(outgoing);
309                 commitFinalResponse(conn, state);
310             } catch (final Exception ex) {
311                 shutdownConnection(conn);
312                 closeHandlers(state);
313                 if (ex instanceof RuntimeException) {
314                     throw (RuntimeException) ex;
315                 } else {
316                     log(ex);
317                 }
318             }
319         }
320     }
321 
322     @Override
323     public void requestReceived(
324             final NHttpServerConnection conn) throws IOException, HttpException {
325         final State state = getState(conn);
326         Asserts.notNull(state, "Connection state");
327         Asserts.check(state.getRequestState() == MessageState.READY,
328                 "Unexpected request state %s", state.getRequestState());
329 
330         final HttpRequest request = conn.getHttpRequest();
331         final HttpContext context = new BasicHttpContext();
332 
333         context.setAttribute(HttpCoreContext.HTTP_REQUEST, request);
334         context.setAttribute(HttpCoreContext.HTTP_CONNECTION, conn);
335         this.httpProcessor.process(request, context);
336 
337         final HttpAsyncRequestHandler<Object> requestHandler = getRequestHandler(request);
338         final HttpAsyncRequestConsumer<Object> consumer = requestHandler.processRequest(request, context);
339         consumer.requestReceived(request);
340 
341         final Incoming incoming = new Incoming(request, requestHandler, consumer, context);
342         state.setIncoming(incoming);
343 
344         if (request instanceof HttpEntityEnclosingRequest) {
345 
346             // If 100-continue is expected make sure
347             // there is no pending response data, no pipelined requests or buffered input
348             if (((HttpEntityEnclosingRequest) request).expectContinue()
349                         && state.getResponseState() == MessageState.READY
350                         && state.getPipeline().isEmpty()
351                         && !(conn instanceof SessionBufferStatus && ((SessionBufferStatus) conn).hasBufferedInput())) {
352 
353                 state.setRequestState(MessageState.ACK_EXPECTED);
354                 final HttpResponse ack = this.responseFactory.newHttpResponse(HttpVersion.HTTP_1_1,
355                         HttpStatus.SC_CONTINUE, context);
356                 if (this.expectationVerifier != null) {
357                     conn.suspendInput();
358                     conn.suspendOutput();
359                     final HttpAsyncExchange httpAsyncExchange = new HttpAsyncExchangeImpl(
360                             request, ack, state, conn, context);
361                     this.expectationVerifier.verify(httpAsyncExchange, context);
362                 } else {
363                     conn.submitResponse(ack);
364                     state.setRequestState(MessageState.BODY_STREAM);
365                 }
366             } else {
367                 state.setRequestState(MessageState.BODY_STREAM);
368             }
369         } else {
370             // No request content is expected. Process request right away
371             completeRequest(incoming, conn, state);
372         }
373     }
374 
375     @Override
376     public void inputReady(
377             final NHttpServerConnection conn,
378             final ContentDecoder decoder) throws IOException, HttpException {
379         final State state = getState(conn);
380         Asserts.notNull(state, "Connection state");
381         Asserts.check(state.getRequestState() == MessageState.BODY_STREAM,
382                 "Unexpected request state %s", state.getRequestState());
383 
384         final Incoming incoming = state.getIncoming();
385         Asserts.notNull(incoming, "Incoming request");
386         final HttpAsyncRequestConsumer<?> consumer = incoming.getConsumer();
387         consumer.consumeContent(decoder, conn);
388         if (decoder.isCompleted()) {
389             completeRequest(incoming, conn, state);
390         }
391     }
392 
393     @Override
394     public void responseReady(
395             final NHttpServerConnection conn) throws IOException, HttpException {
396         final State state = getState(conn);
397         Asserts.notNull(state, "Connection state");
398         Asserts.check(state.getResponseState() == MessageState.READY ||
399                         state.getResponseState() == MessageState.INIT,
400                 "Unexpected response state %s", state.getResponseState());
401 
402         if (state.getRequestState() == MessageState.ACK_EXPECTED) {
403             final Outgoing outgoing;
404             synchronized (state) {
405                 outgoing = state.getOutgoing();
406                 if (outgoing == null) {
407                     conn.suspendOutput();
408                     return;
409                 }
410             }
411             final HttpResponse response = outgoing.getResponse();
412             final int status = response.getStatusLine().getStatusCode();
413             if (status == 100) {
414                 final HttpContext context = outgoing.getContext();
415                 final HttpAsyncResponseProducer responseProducer = outgoing.getProducer();
416                 try {
417                     // Make sure 100 response has no entity
418                     response.setEntity(null);
419                     conn.requestInput();
420                     state.setRequestState(MessageState.BODY_STREAM);
421                     state.setOutgoing(null);
422                     conn.submitResponse(response);
423                     responseProducer.responseCompleted(context);
424                 } finally {
425                     responseProducer.close();
426                 }
427             } else if (status >= 400) {
428                 conn.resetInput();
429                 state.setRequestState(MessageState.READY);
430                 commitFinalResponse(conn, state);
431             } else {
432                 throw new HttpException("Invalid response: " + response.getStatusLine());
433             }
434         } else {
435             if (state.getResponseState() == MessageState.READY) {
436                 final Queue<PipelineEntry> pipeline = state.getPipeline();
437                 final PipelineEntry pipelineEntry = pipeline.poll();
438                 if (pipelineEntry == null) {
439                     conn.suspendOutput();
440                     return;
441                 }
442                 state.setResponseState(MessageState.INIT);
443                 final Object result = pipelineEntry.getResult();
444                 final HttpRequest request = pipelineEntry.getRequest();
445                 final HttpContext context = pipelineEntry.getContext();
446                 if (result != null) {
447                     final HttpResponse response = this.responseFactory.newHttpResponse(HttpVersion.HTTP_1_1,
448                             HttpStatus.SC_OK, context);
449                     final HttpAsyncExchangeImpl httpExchange = new HttpAsyncExchangeImpl(
450                             request, response, state, conn, context);
451                     final HttpAsyncRequestHandler<Object> handler = pipelineEntry.getHandler();
452                     conn.suspendOutput();
453                     try {
454                         handler.handle(result, httpExchange, context);
455                     } catch (final RuntimeException ex) {
456                         throw ex;
457                     } catch (final Exception ex) {
458                         pipeline.add(new PipelineEntry(
459                             request,
460                             null,
461                             ex,
462                             handler,
463                             context));
464                         state.setResponseState(MessageState.READY);
465                         responseReady(conn);
466                         return;
467                     }
468                 } else {
469                     final Exception exception = pipelineEntry.getException();
470                     final HttpAsyncResponseProducer responseProducer = handleException(
471                             exception != null ? exception : new HttpException("Internal error processing request"),
472                             context);
473                     final HttpResponse error = responseProducer.generateResponse();
474                     state.setOutgoing(new Outgoing(request, error, responseProducer, context));
475                 }
476             }
477             if (state.getResponseState() == MessageState.INIT) {
478                 final Outgoing outgoing;
479                 synchronized (state) {
480                     outgoing = state.getOutgoing();
481                     if (outgoing == null) {
482                         conn.suspendOutput();
483                         return;
484                     }
485                 }
486                 final HttpResponse response = outgoing.getResponse();
487                 final int status = response.getStatusLine().getStatusCode();
488                 if (status >= 200) {
489                     commitFinalResponse(conn, state);
490                 } else {
491                     throw new HttpException("Invalid response: " + response.getStatusLine());
492                 }
493             }
494         }
495     }
496 
497     @Override
498     public void outputReady(
499             final NHttpServerConnection conn,
500             final ContentEncoder encoder) throws HttpException, IOException {
501         final State state = getState(conn);
502         Asserts.notNull(state, "Connection state");
503         Asserts.check(state.getResponseState() == MessageState.BODY_STREAM,
504                 "Unexpected response state %s", state.getResponseState());
505 
506         final Outgoing outgoing = state.getOutgoing();
507         Asserts.notNull(outgoing, "Outgoing response");
508         final HttpAsyncResponseProducer responseProducer = outgoing.getProducer();
509 
510         responseProducer.produceContent(encoder, conn);
511 
512         if (encoder.isCompleted()) {
513             completeResponse(outgoing, conn, state);
514         }
515     }
516 
517     @Override
518     public void endOfInput(final NHttpServerConnection conn) throws IOException {
519         // Closing connection in an orderly manner and
520         // waiting for output buffer to get flushed.
521         // Do not want to wait indefinitely, though, in case
522         // the opposite end is not reading
523         if (conn.getSocketTimeout() <= 0) {
524             conn.setSocketTimeout(1000);
525         }
526         conn.close();
527     }
528 
529     @Override
530     public void timeout(final NHttpServerConnection conn) throws IOException {
531         final State state = getState(conn);
532         if (state != null) {
533             exception(conn, new SocketTimeoutException(
534                     String.format("%,d milliseconds timeout on connection %s", conn.getSocketTimeout(), conn)));
535         }
536         if (conn.getStatus() == NHttpConnection.ACTIVE) {
537             conn.close();
538             if (conn.getStatus() == NHttpConnection.CLOSING) {
539                 // Give the connection some grace time to
540                 // close itself nicely
541                 conn.setSocketTimeout(250);
542             }
543         } else {
544             conn.shutdown();
545         }
546     }
547 
548     private State getState(final NHttpConnection conn) {
549         return (State) conn.getContext().getAttribute(HTTP_EXCHANGE_STATE);
550     }
551 
552     /**
553      * This method can be used to log I/O exception thrown while closing
554      * {@link java.io.Closeable} objects (such as
555      * {@link org.apache.http.HttpConnection}).
556      *
557      * @param ex I/O exception thrown by {@link java.io.Closeable#close()}
558      */
559     protected void log(final Exception ex) {
560         this.exceptionLogger.log(ex);
561     }
562 
563     private void shutdownConnection(final NHttpConnection conn) {
564         try {
565             conn.shutdown();
566         } catch (final IOException ex) {
567             log(ex);
568         }
569     }
570 
571     private void closeHandlers(final State state, final Exception ex) {
572         final HttpAsyncRequestConsumer<Object> consumer =
573                 state.getIncoming() != null ? state.getIncoming().getConsumer() : null;
574         if (consumer != null) {
575             try {
576                 consumer.failed(ex);
577             } finally {
578                 try {
579                     consumer.close();
580                 } catch (final IOException ioex) {
581                     log(ioex);
582                 }
583             }
584         }
585         final HttpAsyncResponseProducer producer =
586                 state.getOutgoing() != null ? state.getOutgoing().getProducer() : null;
587         if (producer != null) {
588             try {
589                 producer.failed(ex);
590             } finally {
591                 try {
592                     producer.close();
593                 } catch (final IOException ioex) {
594                     log(ioex);
595                 }
596             }
597         }
598     }
599 
600     private void closeHandlers(final State state) {
601         final HttpAsyncRequestConsumer<Object> consumer =
602                 state.getIncoming() != null ? state.getIncoming().getConsumer() : null;
603         if (consumer != null) {
604             try {
605                 consumer.close();
606             } catch (final IOException ioex) {
607                 log(ioex);
608             }
609         }
610         final HttpAsyncResponseProducer producer =
611                 state.getOutgoing() != null ? state.getOutgoing().getProducer() : null;
612         if (producer != null) {
613             try {
614                 producer.close();
615             } catch (final IOException ioex) {
616                 log(ioex);
617             }
618         }
619     }
620 
621     protected HttpAsyncResponseProducer handleException(
622             final Exception ex, final HttpContext context) {
623         String message = ex.getMessage();
624         if (message == null) {
625             message = ex.toString();
626         }
627         final HttpResponse response = this.responseFactory.newHttpResponse(HttpVersion.HTTP_1_1,
628                 toStatusCode(ex, context), context);
629         return new ErrorResponseProducer(response,
630                 new NStringEntity(message, ContentType.DEFAULT_TEXT), false);
631     }
632 
633     protected int toStatusCode(final Exception ex, final HttpContext context) {
634         final int code;
635         if (ex instanceof MethodNotSupportedException) {
636             code = HttpStatus.SC_NOT_IMPLEMENTED;
637         } else if (ex instanceof UnsupportedHttpVersionException) {
638             code = HttpStatus.SC_HTTP_VERSION_NOT_SUPPORTED;
639         } else if (ex instanceof ProtocolException) {
640             code = HttpStatus.SC_BAD_REQUEST;
641         } else if (ex instanceof SocketTimeoutException) {
642             code = HttpStatus.SC_GATEWAY_TIMEOUT;
643         } else {
644             code = HttpStatus.SC_INTERNAL_SERVER_ERROR;
645         }
646         return code;
647     }
648 
649     /**
650      * This method can be used to handle callback set up happened after
651      * response submission.
652      *
653      * @param cancellable Request cancellation callback.
654      * @param context Request context.
655      *
656      * @since 4.4
657      */
658     protected void handleAlreadySubmittedResponse(
659             final Cancellable cancellable, final HttpContext context) {
660         throw new IllegalStateException("Response already submitted");
661     }
662 
663     /**
664      * This method can be used to handle double response submission.
665      *
666      * @param responseProducer Response producer for second response.
667      * @param context Request context.
668      *
669      * @since 4.4
670      */
671     protected void handleAlreadySubmittedResponse(
672             final HttpAsyncResponseProducer responseProducer,
673             final HttpContext context) {
674         throw new IllegalStateException("Response already submitted");
675     }
676 
677     private boolean canResponseHaveBody(final HttpRequest request, final HttpResponse response) {
678         if (request != null && "HEAD".equalsIgnoreCase(request.getRequestLine().getMethod())) {
679             return false;
680         }
681         final int status = response.getStatusLine().getStatusCode();
682         return status >= HttpStatus.SC_OK
683             && status != HttpStatus.SC_NO_CONTENT
684             && status != HttpStatus.SC_NOT_MODIFIED
685             && status != HttpStatus.SC_RESET_CONTENT;
686     }
687 
688     private void completeRequest(
689             final Incoming incoming,
690             final NHttpServerConnection conn,
691             final State state) throws IOException, HttpException {
692         state.setRequestState(MessageState.READY);
693         state.setIncoming(null);
694 
695         final PipelineEntry pipelineEntry;
696         final HttpAsyncRequestConsumer<?> consumer = incoming.getConsumer();
697         try {
698             final HttpContext context = incoming.getContext();
699             consumer.requestCompleted(context);
700             pipelineEntry = new PipelineEntry(
701                     incoming.getRequest(),
702                     consumer.getResult(),
703                     consumer.getException(),
704                     incoming.getHandler(),
705                     context);
706         } finally {
707             consumer.close();
708         }
709         final Queue<PipelineEntry> pipeline = state.getPipeline();
710         pipeline.add(pipelineEntry);
711         if (state.getResponseState() == MessageState.READY) {
712             conn.requestOutput();
713         }
714     }
715 
716     private void commitFinalResponse(
717             final NHttpServerConnection conn,
718             final State state) throws IOException, HttpException {
719         final Outgoing outgoing = state.getOutgoing();
720         Asserts.notNull(outgoing, "Outgoing response");
721         final HttpRequest request = outgoing.getRequest();
722         final HttpResponse response = outgoing.getResponse();
723         final HttpContext context = outgoing.getContext();
724 
725         context.setAttribute(HttpCoreContext.HTTP_RESPONSE, response);
726         this.httpProcessor.process(response, context);
727 
728         HttpEntity entity = response.getEntity();
729         if (entity != null && !canResponseHaveBody(request, response)) {
730             response.setEntity(null);
731             entity = null;
732         }
733 
734         conn.submitResponse(response);
735 
736         if (entity == null) {
737             completeResponse(outgoing, conn, state);
738         } else {
739             state.setResponseState(MessageState.BODY_STREAM);
740         }
741     }
742 
743     private void completeResponse(
744             final Outgoing outgoing,
745             final NHttpServerConnection conn,
746             final State state) throws IOException, HttpException {
747         final HttpContext context = outgoing.getContext();
748         final HttpResponse response = outgoing.getResponse();
749         final HttpAsyncResponseProducer responseProducer = outgoing.getProducer();
750         try {
751             responseProducer.responseCompleted(context);
752             state.setOutgoing(null);
753             state.setCancellable(null);
754             state.setResponseState(MessageState.READY);
755         } finally {
756             responseProducer.close();
757         }
758         if (!this.connStrategy.keepAlive(response, context)) {
759             conn.close();
760         } else {
761             conn.requestInput();
762         }
763     }
764 
765     @SuppressWarnings("unchecked")
766     private HttpAsyncRequestHandler<Object> getRequestHandler(final HttpRequest request) {
767         HttpAsyncRequestHandler<Object> handler = null;
768         if (this.handlerMapper != null) {
769             handler = (HttpAsyncRequestHandler<Object>) this.handlerMapper.lookup(request);
770         }
771         if (handler == null) {
772             handler = NullRequestHandler.INSTANCE;
773         }
774         return handler;
775     }
776 
777     static class Incoming {
778 
779         private final HttpRequest request;
780         private final HttpAsyncRequestHandler<Object> handler;
781         private final HttpAsyncRequestConsumer<Object> consumer;
782         private final HttpContext context;
783 
784         Incoming(
785                 final HttpRequest request,
786                 final HttpAsyncRequestHandler<Object> handler,
787                 final HttpAsyncRequestConsumer<Object> consumer,
788                 final HttpContext context) {
789             this.request = request;
790             this.handler = handler;
791             this.consumer = consumer;
792             this.context = context;
793         }
794 
795         public HttpRequest getRequest() {
796             return this.request;
797         }
798 
799         public HttpAsyncRequestHandler<Object> getHandler() {
800             return this.handler;
801         }
802 
803         public HttpAsyncRequestConsumer<Object> getConsumer() {
804             return this.consumer;
805         }
806 
807         public HttpContext getContext() {
808             return this.context;
809         }
810     }
811 
812     static class Outgoing {
813 
814         private final HttpRequest request;
815         private final HttpResponse response;
816         private final HttpAsyncResponseProducer producer;
817         private final HttpContext context;
818 
819         Outgoing(
820                 final HttpRequest request,
821                 final HttpResponse response,
822                 final HttpAsyncResponseProducer producer,
823                 final HttpContext context) {
824             this.request = request;
825             this.response = response;
826             this.producer = producer;
827             this.context = context;
828         }
829 
830         public HttpRequest getRequest() {
831             return this.request;
832         }
833 
834         public HttpResponse getResponse() {
835             return this.response;
836         }
837 
838         public HttpAsyncResponseProducer getProducer() {
839             return this.producer;
840         }
841 
842         public HttpContext getContext() {
843             return this.context;
844         }
845     }
846 
847     static class PipelineEntry {
848 
849         private final HttpRequest request;
850         private final Object result;
851         private final Exception exception;
852         private final HttpAsyncRequestHandler<Object> handler;
853         private final HttpContext context;
854 
855         PipelineEntry(
856                 final HttpRequest request,
857                 final Object result,
858                 final Exception exception,
859                 final HttpAsyncRequestHandler<Object> handler,
860                 final HttpContext context) {
861             this.request = request;
862             this.result = result;
863             this.exception = exception;
864             this.handler = handler;
865             this.context = context;
866         }
867 
868         public HttpRequest getRequest() {
869             return this.request;
870         }
871 
872         public Object getResult() {
873             return this.result;
874         }
875 
876         public Exception getException() {
877             return this.exception;
878         }
879 
880         public HttpAsyncRequestHandler<Object> getHandler() {
881             return this.handler;
882         }
883 
884         public HttpContext getContext() {
885             return this.context;
886         }
887 
888     }
889 
890     static class State {
891 
892         private final Queue<PipelineEntry> pipeline;
893         private volatile boolean terminated;
894         private volatile MessageState requestState;
895         private volatile MessageState responseState;
896         private volatile Incoming incoming;
897         private volatile Outgoing outgoing;
898         private volatile Cancellable cancellable;
899 
900         State() {
901             super();
902             this.pipeline = new ConcurrentLinkedQueue<PipelineEntry>();
903             this.requestState = MessageState.READY;
904             this.responseState = MessageState.READY;
905         }
906 
907         public boolean isTerminated() {
908             return this.terminated;
909         }
910 
911         public void setTerminated() {
912             this.terminated = true;
913         }
914 
915         public MessageState getRequestState() {
916             return this.requestState;
917         }
918 
919         public void setRequestState(final MessageState state) {
920             this.requestState = state;
921         }
922 
923         public MessageState getResponseState() {
924             return this.responseState;
925         }
926 
927         public void setResponseState(final MessageState state) {
928             this.responseState = state;
929         }
930 
931         public Incoming getIncoming() {
932             return this.incoming;
933         }
934 
935         public void setIncoming(final Incoming incoming) {
936             this.incoming = incoming;
937         }
938 
939         public Outgoing getOutgoing() {
940             return this.outgoing;
941         }
942 
943         public void setOutgoing(final Outgoing outgoing) {
944             this.outgoing = outgoing;
945         }
946 
947         public Cancellable getCancellable() {
948             return this.cancellable;
949         }
950 
951         public void setCancellable(final Cancellable cancellable) {
952             this.cancellable = cancellable;
953         }
954 
955         public Queue<PipelineEntry> getPipeline() {
956             return this.pipeline;
957         }
958 
959         @Override
960         public String toString() {
961             final StringBuilder buf = new StringBuilder();
962             buf.append("[incoming ");
963             buf.append(this.requestState);
964             if (this.incoming != null) {
965                 buf.append(" ");
966                 buf.append(this.incoming.getRequest().getRequestLine());
967             }
968             buf.append("; outgoing ");
969             buf.append(this.responseState);
970             if (this.outgoing != null) {
971                 buf.append(" ");
972                 buf.append(this.outgoing.getResponse().getStatusLine());
973             }
974             buf.append("]");
975             return buf.toString();
976         }
977 
978     }
979 
980     class HttpAsyncExchangeImpl implements HttpAsyncExchange {
981 
982         private final AtomicBoolean completed = new AtomicBoolean();
983         private final HttpRequest request;
984         private final HttpResponse response;
985         private final State state;
986         private final NHttpServerConnection conn;
987         private final HttpContext context;
988 
989         public HttpAsyncExchangeImpl(
990                 final HttpRequest request,
991                 final HttpResponse response,
992                 final State state,
993                 final NHttpServerConnection conn,
994                 final HttpContext context) {
995             super();
996             this.request = request;
997             this.response = response;
998             this.state = state;
999             this.conn = conn;
1000             this.context = context;
1001         }
1002 
1003         @Override
1004         public HttpRequest getRequest() {
1005             return this.request;
1006         }
1007 
1008         @Override
1009         public HttpResponse getResponse() {
1010             return this.response;
1011         }
1012 
1013         @Override
1014         public void setCallback(final Cancellable cancellable) {
1015             if (this.completed.get()) {
1016                 handleAlreadySubmittedResponse(cancellable, context);
1017             } else if (this.state.isTerminated() && cancellable != null) {
1018                 cancellable.cancel();
1019             } else {
1020                 this.state.setCancellable(cancellable);
1021             }
1022         }
1023 
1024         @Override
1025         public void submitResponse(final HttpAsyncResponseProducer responseProducer) {
1026             Args.notNull(responseProducer, "Response producer");
1027             if (this.completed.getAndSet(true)) {
1028                 handleAlreadySubmittedResponse(responseProducer, context);
1029             } else if (!this.state.isTerminated()) {
1030                 final HttpResponse response = responseProducer.generateResponse();
1031                 final Outgoing outgoing = new Outgoing(
1032                         this.request, response, responseProducer, this.context);
1033 
1034                 synchronized (this.state) {
1035                     this.state.setOutgoing(outgoing);
1036                     this.state.setCancellable(null);
1037                     this.conn.requestOutput();
1038                 }
1039 
1040             } else {
1041                 try {
1042                     responseProducer.close();
1043                 } catch (final IOException ex) {
1044                     log(ex);
1045                 }
1046             }
1047         }
1048 
1049         @Override
1050         public void submitResponse() {
1051             submitResponse(new BasicAsyncResponseProducer(this.response));
1052         }
1053 
1054         @Override
1055         public boolean isCompleted() {
1056             return this.completed.get();
1057         }
1058 
1059         @Override
1060         public void setTimeout(final int timeout) {
1061             this.conn.setSocketTimeout(timeout);
1062         }
1063 
1064         @Override
1065         public int getTimeout() {
1066             return this.conn.getSocketTimeout();
1067         }
1068 
1069     }
1070 
1071     /**
1072      * Adaptor class to transition from HttpAsyncRequestHandlerResolver to HttpAsyncRequestHandlerMapper.
1073      */
1074     @Deprecated
1075     private static class HttpAsyncRequestHandlerResolverAdapter implements HttpAsyncRequestHandlerMapper {
1076 
1077         private final HttpAsyncRequestHandlerResolver resolver;
1078 
1079         public HttpAsyncRequestHandlerResolverAdapter(final HttpAsyncRequestHandlerResolver resolver) {
1080             this.resolver = resolver;
1081         }
1082 
1083         @Override
1084         public HttpAsyncRequestHandler<?> lookup(final HttpRequest request) {
1085             return resolver.lookup(request.getRequestLine().getUri());
1086         }
1087 
1088     }
1089 
1090     /**
1091      * Gets the HttpResponseFactory for this service.
1092      *
1093      * @since 4.4.8
1094      */
1095     protected HttpResponseFactory getResponseFactory() {
1096       return responseFactory;
1097     }
1098 
1099 }