Clarified HttpReceiver.responseFailure().

Added javadocs to relevant methods in HttpChannel.

Signed-off-by: Simone Bordet <simone.bordet@gmail.com>

jetty-core/jetty-client/src/main/java/org/eclipse/jetty/client/HttpChannel.java

@@ -78,6 +78,12 @@ public abstract class HttpChannel implements CyclicTimeouts.Expirable
         return result;
     }
 
+    /**
+     * <p>Disassociates the exchange from this channel.</p>
+     *
+     * @param exchange the current exchange that must be already completed
+     * @return true if the exchange was disassociated, false otherwise
+     */
     public boolean disassociate(HttpExchange exchange)
     {
         boolean result = false;
@@ -97,6 +103,14 @@ public abstract class HttpChannel implements CyclicTimeouts.Expirable
         return result;
     }
 
+    /**
+     * <p>Returns the {@code HttpExchange} currently associated
+     * with this channel, possibly {@code null}.</p>
+     * <p>The exchange may be completed and disassociated concurrently,
+     * so callers must act atomically on the exchange.</p>
+     *
+     * @return the {@code HttpExchange} currently associated with this channel, possibly {@code null}.
+     */
     public HttpExchange getHttpExchange()
     {
         try (AutoLock l = _lock.lock())

jetty-core/jetty-client/src/main/java/org/eclipse/jetty/client/HttpReceiver.java

@@ -386,23 +386,19 @@ public abstract class HttpReceiver
             LOG.debug("Failing with {} on {}", failure, this);
 
         HttpExchange exchange = getHttpExchange();
-        // In case of a response error, the failure has already been notified
-        // and it is possible that a further attempt to read in the receive
-        // loop throws an exception that reenters here but without exchange;
-        // or, the server could just have timed out the connection.
-        if (exchange == null)
-        {
-            promise.succeeded(false);
-            return;
-        }
 
         // Mark atomically the response as completed, with respect
         // to concurrency between response success and response failure.
-        boolean completed = exchange.responseComplete(failure);
+        if (exchange != null && exchange.responseComplete(failure))
-        if (completed)
+        {
             abort(exchange, failure, promise);
+        }
         else
+        {
+            // The response was already completed (either successfully
+            // or with a failure) by a previous event, bail out.
             promise.succeeded(false);
+        }
     }
 
     private void terminateResponse(HttpExchange exchange)