Issue #841 support reset in buffering interceptors

Added resetBuffers to the output interceptor.

jetty-server/src/main/java/org/eclipse/jetty/server/HttpChannel.java

@@ -765,6 +765,13 @@ public class HttpChannel implements Runnable, HttpOutput.Interceptor
         sendResponse(null,content,complete,callback);
     }
     
+    @Override 
+    public void resetBuffer()
+    {
+        if(isCommitted())
+            throw new IllegalStateException("Committed");
+    }
+
     public HttpOutput.Interceptor getNextInterceptor()
     {
         return null;

jetty-server/src/main/java/org/eclipse/jetty/server/HttpOutput.java

@@ -55,11 +55,65 @@ import org.eclipse.jetty.util.log.Logger;
  */
 public class HttpOutput extends ServletOutputStream implements Runnable
 {   
+    
+    /**
+     * The HttpOutput.Inteceptor is a single intercept point for all 
+     * output written to the HttpOutput: via writer; via output stream; 
+     * asynchronously; or blocking.
+     * <p>
+     * The Interceptor can be used to implement translations (eg Gzip) or 
+     * additional buffering that acts on all output.  Interceptors are 
+     * created in a chain, so that multiple concerns may intercept.
+     * <p>
+     * The {@link HttpChannel} is an {@link Interceptor} and is always the 
+     * last link in any Interceptor chain.
+     * <p>
+     * Responses are committed by the first call to 
+     * {@link #write(ByteBuffer, boolean, Callback)}
+     * and closed by a call to {@link #write(ByteBuffer, boolean, Callback)} 
+     * with the last boolean set true.  If no content is available to commit 
+     * or close, then a null buffer is passed.
+     */
     public interface Interceptor
     {
-        void write(ByteBuffer content, boolean complete, Callback callback);
+        /** 
+         * Write content.
+         * The response is committed by the first call to write and is closed by
+         * a call with last == true. Empty content buffers may be passed to 
+         * force a commit or close.
+         * @param content The content to be written or an empty buffer.
+         * @param last True if this is the last call to write 
+         * @param callback The callback to use to indicate {@link Callback#succeeded()} 
+         * or {@link Callback#failed(Throwable)}.
+         */
+        void write(ByteBuffer content, boolean last, Callback callback);
+        
+        /**
+         * @return The next Interceptor in the chain or null if this is the 
+         * last Interceptor in the chain.
+         */
         Interceptor getNextInterceptor();
+        
+        /**
+         * @return True if the Interceptor is optimized to receive direct 
+         * {@link ByteBuffer}s in the {@link #write(ByteBuffer, boolean, Callback)}
+         * method.   If false is returned, then passing direct buffers may cause 
+         * inefficiencies.
+         */
         boolean isOptimizedForDirectBuffers();
+        
+        /**
+         * Reset the buffers.
+         * <p>If the Interceptor contains buffers then reset them.
+         * @throws IllegalStateException Thrown if the response has been 
+         * committed and buffers and/or headers cannot be reset.
+         */
+        default void resetBuffer() throws IllegalStateException
+        {
+            Interceptor next = getNextInterceptor();
+            if (next!=null)
+                next.resetBuffer();
+        };
     }
 
     private static Logger LOG = Log.getLogger(HttpOutput.class);
@@ -820,15 +874,19 @@ public class HttpOutput extends ServletOutputStream implements Runnable
 
     public void recycle()
     {
-        resetBuffer();
         _interceptor=_channel;
+        if (BufferUtil.hasContent(_aggregate))
+            BufferUtil.clear(_aggregate);
+        _written = 0;
+        reopen();
     }
 
     public void resetBuffer()
     {
-        _written = 0;
+        _interceptor.resetBuffer();
         if (BufferUtil.hasContent(_aggregate))
             BufferUtil.clear(_aggregate);
+        _written = 0;
         reopen();
     }
 

jetty-server/src/main/java/org/eclipse/jetty/server/Response.java

@@ -543,8 +543,9 @@ public class Response implements HttpServletResponse
 
         if (isCommitted())
             LOG.warn("cannot sendError("+code+", "+message+") response already committed");
-
+        else
             resetBuffer();
+        
         _characterEncoding=null;
         setHeader(HttpHeader.EXPIRES,null);
         setHeader(HttpHeader.LAST_MODIFIED,null);
@@ -1255,9 +1256,6 @@ public class Response implements HttpServletResponse
     @Override
     public void resetBuffer()
     {
-        if (isCommitted())
-            throw new IllegalStateException("cannot reset buffer on committed response");
-
         _out.resetBuffer();
     }
 

jetty-server/src/main/java/org/eclipse/jetty/server/handler/BufferedResponseHandler.java

@@ -202,6 +202,14 @@ public class BufferedResponseHandler extends HandlerWrapper
             _channel=httpChannel;
         }
         
+        @Override
+        public void resetBuffer() 
+        {
+            _buffers.clear();
+            _aggregating=null;
+            _aggregate=null;
+        };
+
         @Override
         public void write(ByteBuffer content, boolean last, Callback callback)
         {

jetty-server/src/test/java/org/eclipse/jetty/server/handler/BufferedResponseHandlerTest.java

@@ -41,8 +41,6 @@ import org.junit.Test;
 
 /**
  * Resource Handler test
- * 
- * TODO: increase the testing going on here
  */
 public class BufferedResponseHandlerTest
 {
@@ -95,6 +93,7 @@ public class BufferedResponseHandlerTest
         _test._writes=10;
         _test._flush=false;
         _test._close=false;
+        _test._reset=false;
     }
 
     @Test
@@ -219,6 +218,18 @@ public class BufferedResponseHandlerTest
         assertThat(response,containsString("Written: true"));
     }
 
+    @Test
+    public void testReset() throws Exception
+    {
+        _test._reset=true;
+        String response = _local.getResponse("GET /ctx/include/path HTTP/1.1\r\nHost: localhost\r\n\r\n");
+        assertThat(response,containsString(" 200 OK"));
+        assertThat(response,containsString("Write: 0"));
+        assertThat(response,containsString("Write: 9"));
+        assertThat(response,containsString("Written: true"));
+        assertThat(response,not(containsString("RESET")));
+    }
+    
     public static class TestHandler extends AbstractHandler
     {
         int _bufferSize;
@@ -227,16 +238,25 @@ public class BufferedResponseHandlerTest
         int _writes;
         boolean _flush;
         boolean _close;
+        boolean _reset;
 
         @Override
         public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
         {
             baseRequest.setHandled(true);
+            
             if (_bufferSize>0)
                 response.setBufferSize(_bufferSize);
             if (_mimeType!=null)
                 response.setContentType(_mimeType);
 
+            if (_reset)
+            {
+                response.getOutputStream().print("THIS WILL BE RESET");
+                response.getOutputStream().flush();
+                response.getOutputStream().print("THIS WILL BE RESET");
+                response.resetBuffer();
+            }
             for (int i=0;i<_writes;i++)
             {
                 response.addHeader("Write",Integer.toString(i));
@@ -249,6 +269,5 @@ public class BufferedResponseHandlerTest
                 response.getOutputStream().close();
             response.addHeader("Written","true");
         }  
-        
     }
 }