Optimize request buffer release #12239

jetty-core/jetty-http/src/main/java/org/eclipse/jetty/http/HttpParser.java

@@ -422,6 +422,11 @@ public State getState()
         return _state;
     }
 
+    public boolean hasContent()
+    {
+        return _endOfContent != EndOfContent.NO_CONTENT;
+    }
+
     public boolean inContentState()
     {
         return _state.ordinal() >= State.CONTENT.ordinal() && _state.ordinal() < State.END.ordinal();

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/internal/HttpConnection.java

@@ -398,6 +398,15 @@ public void onFillable()
                     if (LOG.isDebugEnabled())
                         LOG.debug("HANDLE {} {}", request, this);
 
+                    // If the buffer is empty and no body is expected, then release the buffer
+                    if (isRequestBufferEmpty() && !_parser.hasContent())
+                    {
+                        // try parsing now to the end of the message
+                        parseRequestBuffer();
+                        if (_parser.isComplete())
+                            releaseRequestBuffer();
+                    }
+
                     // Handle the request by running the task.
                     _handling.set(true);
                     Runnable onRequest = _onRequest;
@@ -424,7 +433,15 @@ public void onFillable()
                     {
                         if (LOG.isDebugEnabled())
                             LOG.debug("upgraded {} -> {}", this, getEndPoint().getConnection());
-                        releaseRequestBuffer();
+                        if (_requestBuffer != null)
+                            releaseRequestBuffer();
+                        break;
+                    }
+
+                    // If we have already released the request buffer, then use fill interest before allocating another
+                    if (_requestBuffer == null)
+                    {
+                        fillInterested();
                         break;
                     }
                 }