Issue #5368 - changes from review

Signed-off-by: Lachlan Roberts <lachlan@webtide.com>

jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/message/MessageInputStream.java

@@ -53,9 +53,24 @@ public class MessageInputStream extends InputStream implements MessageAppender
 
     private enum State
     {
+        /**
+         * Open and waiting for a frame to be delivered in {@link #appendFrame(ByteBuffer, boolean)}.
+         */
         RESUMED,
+
+        /**
+         * We have suspended the session after reading a websocket frame but have not reached the end of the message.
+         */
         SUSPENDED,
+
+        /**
+         * We have received a frame with fin==true and have suspended until we are signaled that onMessage method exited.
+         */
         COMPLETE,
+
+        /**
+         * We have read to EOF or someone has called InputStream.close(), any further reads will result in reading -1.
+         */
         CLOSED
     }
 
@@ -99,13 +114,17 @@ public void appendFrame(ByteBuffer framePayload, boolean fin) throws IOException
                             break;
 
                         default:
-                            throw new IllegalStateException();
+                            throw new IllegalStateException("Incorrect State: " + state.name());
                     }
 
                     // Put the payload into the queue, by copying it.
                     // Copying is necessary because the payload will
                     // be processed after this method returns.
-                    buffers.put(copy(framePayload));
+                    ByteBuffer copy = acquire(framePayload.remaining(), framePayload.isDirect());
+                    BufferUtil.clearToFill(copy);
+                    copy.put(framePayload);
+                    BufferUtil.flipToFlush(copy, 0);
+                    buffers.put(copy);
                 }
 
                 if (fin)
@@ -134,7 +153,7 @@ public void close()
                 (activeBuffer != null && activeBuffer.hasRemaining());
 
             if (remainingContent)
-                LOG.warn("MessageInputStream closed without fully consuming content");
+                LOG.warn("MessageInputStream closed without fully consuming content {}", session);
 
             state = State.CLOSED;
             buffers.clear();
@@ -187,7 +206,6 @@ public int read(byte[] b, int off, int len) throws IOException
                 return -1;
             }
 
-            // todo: what if we get a buffer with no content and we never resume
             // grab a fresh buffer
             while (activeBuffer == null || !activeBuffer.hasRemaining())
             {
@@ -245,7 +263,7 @@ public int read(byte[] b, int off, int len) throws IOException
                             break;
 
                         case RESUMED:
-                            throw new IllegalStateException();
+                            throw new IllegalStateException("Incorrect State: " + state.name());
                     }
                 }
 
@@ -289,15 +307,6 @@ public boolean markSupported()
         return false;
     }
 
-    private ByteBuffer copy(ByteBuffer buffer)
-    {
-        ByteBuffer copy = acquire(buffer.remaining(), buffer.isDirect());
-        BufferUtil.clearToFill(copy);
-        copy.put(buffer);
-        BufferUtil.flipToFlush(copy, 0);
-        return copy;
-    }
-
     private ByteBuffer acquire(int capacity, boolean direct)
     {
         ByteBuffer buffer;