470727 - Thread Starvation of selector wakeups.

Changed the CallBack.NonBlocking to a default Callback.isNonBlocking, so that wrapping callbacks can determine if they are NonBlocking or not.

jetty-client/src/main/java/org/eclipse/jetty/client/HttpSender.java

@@ -672,6 +672,13 @@ public abstract class HttpSender implements AsyncContentProvider.Listener
 
     private class CommitCallback implements Callback
     {
+
+        @Override
+        public boolean isNonBlocking()
+        {
+            return content.isNonBlocking();
+        }
+        
         @Override
         public void succeeded()
         {
@@ -882,6 +889,12 @@ public abstract class HttpSender implements AsyncContentProvider.Listener
 
     private class LastContentCallback implements Callback
     {
+        @Override
+        public boolean isNonBlocking()
+        {
+            return content.isNonBlocking();
+        }
+        
         @Override
         public void succeeded()
         {

jetty-client/src/main/java/org/eclipse/jetty/client/http/HttpSenderOverHTTP.java

@@ -230,6 +230,12 @@ public class HttpSenderOverHTTP extends HttpSender
             this.buffers = buffers;
         }
 
+        @Override
+        public boolean isNonBlocking()
+        {
+            return callback.isNonBlocking();
+        }
+
         @Override
         public void succeeded()
         {

jetty-client/src/main/java/org/eclipse/jetty/client/util/DeferredContentProvider.java

@@ -87,7 +87,7 @@ import org.eclipse.jetty.util.Callback;
  */
 public class DeferredContentProvider implements AsyncContentProvider, Callback, Closeable
 {
-    private static final Chunk CLOSE = new Chunk(BufferUtil.EMPTY_BUFFER, Callback.Adapter.INSTANCE);
+    private static final Chunk CLOSE = new Chunk(BufferUtil.EMPTY_BUFFER, Callback.NOOP);
 
     private final Object lock = this;
     private final ArrayQueue<Chunk> chunks = new ArrayQueue<>(4, 64, lock);
@@ -143,7 +143,7 @@ public class DeferredContentProvider implements AsyncContentProvider, Callback,
      */
     public boolean offer(ByteBuffer buffer)
     {
-        return offer(buffer, Callback.Adapter.INSTANCE);
+        return offer(buffer, Callback.NOOP);
     }
 
     public boolean offer(ByteBuffer buffer, Callback callback)

jetty-client/src/main/java/org/eclipse/jetty/client/util/OutputStreamContentProvider.java

@@ -78,6 +78,12 @@ public class OutputStreamContentProvider implements AsyncContentProvider, Callba
     private final DeferredContentProvider deferred = new DeferredContentProvider();
     private final OutputStream output = new DeferredOutputStream();
 
+    @Override
+    public boolean isNonBlocking()
+    {
+        return deferred.isNonBlocking();
+    }
+    
     @Override
     public long getLength()
     {

jetty-client/src/test/java/org/eclipse/jetty/client/HttpClientFailureTest.java

@@ -157,7 +157,7 @@ public class HttpClientFailureTest
 
         Assert.assertTrue(commitLatch.await(5, TimeUnit.SECONDS));
         final CountDownLatch contentLatch = new CountDownLatch(1);
-        content.offer(ByteBuffer.allocate(1024), new Callback.Adapter()
+        content.offer(ByteBuffer.allocate(1024), new Callback()
         {
             @Override
             public void failed(Throwable x)

jetty-client/src/test/java/org/eclipse/jetty/client/HttpClientStreamTest.java

@@ -691,7 +691,7 @@ public class HttpClientStreamTest extends AbstractHttpClientServerTest
         try (DeferredContentProvider content = new DeferredContentProvider())
         {
             // Make the content immediately available.
-            content.offer(ByteBuffer.allocate(1024), new Callback.Adapter()
+            content.offer(ByteBuffer.allocate(1024), new Callback()
             {
                 @Override
                 public void succeeded()
@@ -976,7 +976,7 @@ public class HttpClientStreamTest extends AbstractHttpClientServerTest
         start(new EmptyServerHandler());
 
         final CountDownLatch failLatch = new CountDownLatch(2);
-        final Callback.Adapter callback = new Callback.Adapter()
+        final Callback callback = new Callback()
         {
             @Override
             public void failed(Throwable x)
@@ -1014,7 +1014,7 @@ public class HttpClientStreamTest extends AbstractHttpClientServerTest
 
         // Make sure that adding more content results in the callback to be failed.
         final CountDownLatch latch = new CountDownLatch(1);
-        content.offer(ByteBuffer.wrap(new byte[128]), new Callback.Adapter()
+        content.offer(ByteBuffer.wrap(new byte[128]), new Callback()
         {
             @Override
             public void failed(Throwable x)

jetty-fcgi/fcgi-client/src/main/java/org/eclipse/jetty/fcgi/client/http/HttpSenderOverFCGI.java

@@ -99,7 +99,7 @@ public class HttpSenderOverFCGI extends HttpSender
         int id = getHttpChannel().getRequest();
         boolean hasContent = content.hasContent();
         Generator.Result headersResult = generator.generateRequestHeaders(id, fcgiHeaders,
-                hasContent ? callback : Callback.Adapter.INSTANCE);
+                hasContent ? callback : Callback.NOOP);
         if (hasContent)
         {
             getHttpChannel().flush(headersResult);

jetty-fcgi/fcgi-server/src/main/java/org/eclipse/jetty/fcgi/server/HttpTransportOverFCGI.java

@@ -105,7 +105,7 @@ public class HttpTransportOverFCGI implements HttpTransport
         {
             if (lastContent)
             {
-                Generator.Result headersResult = generateResponseHeaders(info, Callback.Adapter.INSTANCE);
+                Generator.Result headersResult = generateResponseHeaders(info, Callback.NOOP);
                 Generator.Result contentResult = generateResponseContent(BufferUtil.EMPTY_BUFFER, true, callback);
                 flusher.flush(headersResult, contentResult);
             }
@@ -117,7 +117,7 @@ public class HttpTransportOverFCGI implements HttpTransport
         }
         else
         {
-            Generator.Result headersResult = generateResponseHeaders(info, Callback.Adapter.INSTANCE);
+            Generator.Result headersResult = generateResponseHeaders(info, Callback.NOOP);
             Generator.Result contentResult = generateResponseContent(content, lastContent, callback);
             flusher.flush(headersResult, contentResult);
         }

jetty-http2/http2-client/src/main/java/org/eclipse/jetty/http2/client/HTTP2Client.java

@@ -299,7 +299,7 @@ public class HTTP2Client extends ContainerLifeCycle
     private void closeConnections()
     {
         for (ISession session : sessions)
-            session.close(ErrorCode.NO_ERROR.code, null, Callback.Adapter.INSTANCE);
+            session.close(ErrorCode.NO_ERROR.code, null, Callback.NOOP);
         sessions.clear();
     }
 

jetty-http2/http2-client/src/main/java/org/eclipse/jetty/http2/client/HTTP2ClientSession.java

@@ -55,7 +55,7 @@ public class HTTP2ClientSession extends HTTP2Session
         }
         else
         {
-            stream.process(frame, Callback.Adapter.INSTANCE);
+            stream.process(frame, Callback.NOOP);
             notifyHeaders(stream, frame);
         }
     }
@@ -92,7 +92,7 @@ public class HTTP2ClientSession extends HTTP2Session
         else
         {
             IStream pushStream = createRemoteStream(pushStreamId);
-            pushStream.process(frame, Callback.Adapter.INSTANCE);
+            pushStream.process(frame, Callback.NOOP);
             Stream.Listener listener = notifyPush(stream, pushStream, frame);
             pushStream.setListener(listener);
         }

jetty-http2/http2-client/src/test/java/org/eclipse/jetty/http2/client/AsyncIOTest.java

@@ -94,7 +94,7 @@ public class AsyncIOTest extends AbstractTest
             }
         });
         Stream stream = promise.get(5, TimeUnit.SECONDS);
-        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(16), true), Callback.Adapter.INSTANCE);
+        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(16), true), Callback.NOOP);
 
         Assert.assertTrue(latch.await(5, TimeUnit.SECONDS));
     }
@@ -148,7 +148,7 @@ public class AsyncIOTest extends AbstractTest
 
         // Wait until service() returns.
         Thread.sleep(1000);
-        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(16), true), Callback.Adapter.INSTANCE);
+        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(16), true), Callback.NOOP);
 
         Assert.assertTrue(latch.await(5, TimeUnit.SECONDS));
     }
@@ -204,11 +204,11 @@ public class AsyncIOTest extends AbstractTest
 
         // Wait until service() returns.
         Thread.sleep(1000);
-        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(1), false), Callback.Adapter.INSTANCE);
+        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(1), false), Callback.NOOP);
 
         // Wait until onDataAvailable() returns.
         Thread.sleep(1000);
-        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(1), true), Callback.Adapter.INSTANCE);
+        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(1), true), Callback.NOOP);
 
         Assert.assertTrue(latch.await(5, TimeUnit.SECONDS));
         // Make sure onDataAvailable() has been called twice

jetty-http2/http2-client/src/test/java/org/eclipse/jetty/http2/client/FlowControlStrategyTest.java

@@ -247,7 +247,7 @@ public abstract class FlowControlStrategyTest
                 HttpFields fields = new HttpFields();
                 MetaData.Response response = new MetaData.Response(HttpVersion.HTTP_2, 200, fields);
                 HeadersFrame responseFrame = new HeadersFrame(stream.getId(), response, null, true);
-                stream.headers(responseFrame, Callback.Adapter.INSTANCE);
+                stream.headers(responseFrame, Callback.NOOP);
 
                 return new Stream.Listener.Adapter()
                 {
@@ -263,7 +263,7 @@ public abstract class FlowControlStrategyTest
                             callbackRef.set(callback);
                             Map<Integer, Integer> settings = new HashMap<>();
                             settings.put(SettingsFrame.INITIAL_WINDOW_SIZE, size);
-                            stream.getSession().settings(new SettingsFrame(settings, false), Callback.Adapter.INSTANCE);
+                            stream.getSession().settings(new SettingsFrame(settings, false), Callback.NOOP);
                             // Do not succeed the callback here.
                         }
                         else if (dataFrameCount > 1)
@@ -293,11 +293,11 @@ public abstract class FlowControlStrategyTest
         Stream stream = promise.get(5, TimeUnit.SECONDS);
 
         // Send first chunk that exceeds the window.
-        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(size * 2), false), Callback.Adapter.INSTANCE);
+        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(size * 2), false), Callback.NOOP);
         settingsLatch.await(5, TimeUnit.SECONDS);
 
         // Send the second chunk of data, must not arrive since we're flow control stalled on the client.
-        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(size * 2), true), Callback.Adapter.INSTANCE);
+        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(size * 2), true), Callback.NOOP);
         Assert.assertFalse(dataLatch.await(1, TimeUnit.SECONDS));
 
         // Consume the data arrived to server, this will resume flow control on the client.
@@ -325,10 +325,10 @@ public abstract class FlowControlStrategyTest
             {
                 MetaData.Response metaData = new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields());
                 HeadersFrame responseFrame = new HeadersFrame(stream.getId(), metaData, null, false);
-                stream.headers(responseFrame, Callback.Adapter.INSTANCE);
+                stream.headers(responseFrame, Callback.NOOP);
 
                 DataFrame dataFrame = new DataFrame(stream.getId(), ByteBuffer.allocate(length), true);
-                stream.data(dataFrame, Callback.Adapter.INSTANCE);
+                stream.data(dataFrame, Callback.NOOP);
                 return null;
             }
         });
@@ -337,7 +337,7 @@ public abstract class FlowControlStrategyTest
 
         Map<Integer, Integer> settings = new HashMap<>();
         settings.put(SettingsFrame.INITIAL_WINDOW_SIZE, windowSize);
-        session.settings(new SettingsFrame(settings, false), Callback.Adapter.INSTANCE);
+        session.settings(new SettingsFrame(settings, false), Callback.NOOP);
 
         Assert.assertTrue(settingsLatch.await(5, TimeUnit.SECONDS));
 
@@ -417,7 +417,7 @@ public abstract class FlowControlStrategyTest
             {
                 MetaData.Response metaData = new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields());
                 HeadersFrame responseFrame = new HeadersFrame(stream.getId(), metaData, null, false);
-                stream.headers(responseFrame, Callback.Adapter.INSTANCE);
+                stream.headers(responseFrame, Callback.NOOP);
                 return new Stream.Listener.Adapter()
                 {
                     private AtomicInteger dataFrames = new AtomicInteger();
@@ -474,7 +474,7 @@ public abstract class FlowControlStrategyTest
 
         final int length = 5 * windowSize;
         DataFrame dataFrame = new DataFrame(stream.getId(), ByteBuffer.allocate(length), true);
-        stream.data(dataFrame, Callback.Adapter.INSTANCE);
+        stream.data(dataFrame, Callback.NOOP);
 
         Callback callback = exchanger.exchange(null, 5, TimeUnit.SECONDS);
         checkThatWeAreFlowControlStalled(exchanger);
@@ -519,7 +519,7 @@ public abstract class FlowControlStrategyTest
                     // Send data to consume most of the session window.
                     ByteBuffer data = ByteBuffer.allocate(FlowControlStrategy.DEFAULT_WINDOW_SIZE - windowSize);
                     DataFrame dataFrame = new DataFrame(stream.getId(), data, true);
-                    stream.data(dataFrame, Callback.Adapter.INSTANCE);
+                    stream.data(dataFrame, Callback.NOOP);
                     return null;
                 }
                 else
@@ -527,9 +527,9 @@ public abstract class FlowControlStrategyTest
                     // For every stream, send down half the window size of data.
                     MetaData.Response metaData = new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields());
                     HeadersFrame responseFrame = new HeadersFrame(stream.getId(), metaData, null, false);
-                    stream.headers(responseFrame, Callback.Adapter.INSTANCE);
+                    stream.headers(responseFrame, Callback.NOOP);
                     DataFrame dataFrame = new DataFrame(stream.getId(), ByteBuffer.allocate(windowSize / 2), true);
-                    stream.data(dataFrame, Callback.Adapter.INSTANCE);
+                    stream.data(dataFrame, Callback.NOOP);
                     return null;
                 }
             }
@@ -615,9 +615,9 @@ public abstract class FlowControlStrategyTest
             {
                 MetaData.Response metaData = new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields());
                 HeadersFrame responseFrame = new HeadersFrame(stream.getId(), metaData, null, false);
-                stream.headers(responseFrame, Callback.Adapter.INSTANCE);
+                stream.headers(responseFrame, Callback.NOOP);
                 DataFrame dataFrame = new DataFrame(stream.getId(), ByteBuffer.wrap(data), true);
-                stream.data(dataFrame, Callback.Adapter.INSTANCE);
+                stream.data(dataFrame, Callback.NOOP);
                 return null;
             }
         });
@@ -675,8 +675,8 @@ public abstract class FlowControlStrategyTest
             @Override
             public Stream.Listener onNewStream(Stream stream, HeadersFrame frame)
             {
-                stream.data(new DataFrame(stream.getId(), ByteBuffer.wrap(chunk1), false), Callback.Adapter.INSTANCE);
+                stream.data(new DataFrame(stream.getId(), ByteBuffer.wrap(chunk1), false), Callback.NOOP);
-                stream.data(new DataFrame(stream.getId(), ByteBuffer.wrap(chunk2), true), Callback.Adapter.INSTANCE);
+                stream.data(new DataFrame(stream.getId(), ByteBuffer.wrap(chunk2), true), Callback.NOOP);
                 dataLatch.countDown();
                 return null;
             }
@@ -685,7 +685,7 @@ public abstract class FlowControlStrategyTest
         Session session = newClient(new Session.Listener.Adapter());
         Map<Integer, Integer> settings = new HashMap<>();
         settings.put(SettingsFrame.INITIAL_WINDOW_SIZE, 0);
-        session.settings(new SettingsFrame(settings, false), Callback.Adapter.INSTANCE);
+        session.settings(new SettingsFrame(settings, false), Callback.NOOP);
         Assert.assertTrue(settingsLatch.get().await(5, TimeUnit.SECONDS));
 
         byte[] content = new byte[chunk1.length + chunk2.length];
@@ -712,7 +712,7 @@ public abstract class FlowControlStrategyTest
         settingsLatch.set(new CountDownLatch(1));
         settings.clear();
         settings.put(SettingsFrame.INITIAL_WINDOW_SIZE, chunk1.length / 2);
-        session.settings(new SettingsFrame(settings, false), Callback.Adapter.INSTANCE);
+        session.settings(new SettingsFrame(settings, false), Callback.NOOP);
         Assert.assertTrue(settingsLatch.get().await(5, TimeUnit.SECONDS));
 
         Assert.assertTrue(responseLatch.await(5, TimeUnit.SECONDS));
@@ -734,7 +734,7 @@ public abstract class FlowControlStrategyTest
             {
                 MetaData metaData = new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields());
                 HeadersFrame responseFrame = new HeadersFrame(stream.getId(), metaData, null, false);
-                stream.headers(responseFrame, Callback.Adapter.INSTANCE);
+                stream.headers(responseFrame, Callback.NOOP);
                 return new Stream.Listener.Adapter()
                 {
                     @Override
@@ -787,7 +787,7 @@ public abstract class FlowControlStrategyTest
 
         ByteBuffer requestContent = ByteBuffer.wrap(requestData);
         DataFrame dataFrame = new DataFrame(stream.getId(), requestContent, true);
-        stream.data(dataFrame, Callback.Adapter.INSTANCE);
+        stream.data(dataFrame, Callback.NOOP);
 
         Assert.assertTrue(latch.await(5, TimeUnit.SECONDS));
 
@@ -820,7 +820,7 @@ public abstract class FlowControlStrategyTest
         Stream stream = streamPromise.get(5, TimeUnit.SECONDS);
         ByteBuffer data = ByteBuffer.allocate(FlowControlStrategy.DEFAULT_WINDOW_SIZE);
         final CountDownLatch dataLatch = new CountDownLatch(1);
-        stream.data(new DataFrame(stream.getId(), data, false), new Callback.Adapter()
+        stream.data(new DataFrame(stream.getId(), data, false), new Callback.NonBlocking()
         {
             @Override
             public void succeeded()
@@ -845,7 +845,7 @@ public abstract class FlowControlStrategyTest
         ByteBuffer extraData = ByteBuffer.allocate(1024);
         http2Session.getGenerator().data(lease, new DataFrame(stream.getId(), extraData, true), extraData.remaining());
         List<ByteBuffer> buffers = lease.getByteBuffers();
-        http2Session.getEndPoint().write(Callback.Adapter.INSTANCE, buffers.toArray(new ByteBuffer[buffers.size()]));
+        http2Session.getEndPoint().write(Callback.NOOP, buffers.toArray(new ByteBuffer[buffers.size()]));
 
         // Expect the connection to be closed.
         Assert.assertTrue(closeLatch.await(5, TimeUnit.SECONDS));
@@ -885,7 +885,7 @@ public abstract class FlowControlStrategyTest
         Stream stream = streamPromise.get(5, TimeUnit.SECONDS);
         ByteBuffer data = ByteBuffer.allocate(FlowControlStrategy.DEFAULT_WINDOW_SIZE);
         final CountDownLatch dataLatch = new CountDownLatch(1);
-        stream.data(new DataFrame(stream.getId(), data, false), new Callback.Adapter()
+        stream.data(new DataFrame(stream.getId(), data, false), new Callback.NonBlocking()
         {
             @Override
             public void succeeded()
@@ -906,7 +906,7 @@ public abstract class FlowControlStrategyTest
         ByteBuffer extraData = ByteBuffer.allocate(1024);
         http2Session.getGenerator().data(lease, new DataFrame(stream.getId(), extraData, true), extraData.remaining());
         List<ByteBuffer> buffers = lease.getByteBuffers();
-        http2Session.getEndPoint().write(Callback.Adapter.INSTANCE, buffers.toArray(new ByteBuffer[buffers.size()]));
+        http2Session.getEndPoint().write(Callback.NOOP, buffers.toArray(new ByteBuffer[buffers.size()]));
 
         // Expect the connection to be closed.
         Assert.assertTrue(closeLatch.await(5, TimeUnit.SECONDS));
@@ -936,7 +936,7 @@ public abstract class FlowControlStrategyTest
                         // stream is reset, and automatically consumed to
                         // keep the session window large for other streams.
                         callback.failed(new Throwable());
-                        stream.reset(new ResetFrame(stream.getId(), ErrorCode.CANCEL_STREAM_ERROR.code), Callback.Adapter.INSTANCE);
+                        stream.reset(new ResetFrame(stream.getId(), ErrorCode.CANCEL_STREAM_ERROR.code), Callback.NOOP);
                     }
                 };
             }
@@ -960,7 +960,7 @@ public abstract class FlowControlStrategyTest
         // Perform a big upload that will stall the flow control windows.
         ByteBuffer data = ByteBuffer.allocate(5 * FlowControlStrategy.DEFAULT_WINDOW_SIZE);
         final CountDownLatch dataLatch = new CountDownLatch(1);
-        stream.data(new DataFrame(stream.getId(), data, true), new Callback.Adapter()
+        stream.data(new DataFrame(stream.getId(), data, true), new Callback.NonBlocking()
         {
             @Override
             public void failed(Throwable x)

jetty-http2/http2-client/src/test/java/org/eclipse/jetty/http2/client/IdleTimeoutTest.java

@@ -65,7 +65,7 @@ public class IdleTimeoutTest extends AbstractTest
                 stream.setIdleTimeout(10 * idleTimeout);
                 MetaData.Response metaData = new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields());
                 HeadersFrame responseFrame = new HeadersFrame(stream.getId(), metaData, null, true);
-                stream.headers(responseFrame, Callback.Adapter.INSTANCE);
+                stream.headers(responseFrame, Callback.NOOP);
                 return null;
             }
         });
@@ -154,7 +154,7 @@ public class IdleTimeoutTest extends AbstractTest
                 sleep(idleTimeout + idleTimeout / 2);
                 MetaData.Response metaData = new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields());
                 HeadersFrame responseFrame = new HeadersFrame(stream.getId(), metaData, null, true);
-                stream.headers(responseFrame, Callback.Adapter.INSTANCE);
+                stream.headers(responseFrame, Callback.NOOP);
                 return null;
             }
         });
@@ -207,7 +207,7 @@ public class IdleTimeoutTest extends AbstractTest
                 stream.setIdleTimeout(10 * idleTimeout);
                 MetaData.Response metaData = new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields());
                 HeadersFrame responseFrame = new HeadersFrame(stream.getId(), metaData, null, true);
-                stream.headers(responseFrame, Callback.Adapter.INSTANCE);
+                stream.headers(responseFrame, Callback.NOOP);
                 return null;
             }
 
@@ -285,7 +285,7 @@ public class IdleTimeoutTest extends AbstractTest
                 stream.setIdleTimeout(10 * idleTimeout);
                 MetaData.Response metaData = new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields());
                 HeadersFrame responseFrame = new HeadersFrame(stream.getId(), metaData, null, true);
-                stream.headers(responseFrame, Callback.Adapter.INSTANCE);
+                stream.headers(responseFrame, Callback.NOOP);
                 return null;
             }
 
@@ -452,7 +452,7 @@ public class IdleTimeoutTest extends AbstractTest
 
         sleep(idleTimeout / 2);
         final CountDownLatch dataLatch = new CountDownLatch(1);
-        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(1), false), new Callback.Adapter()
+        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(1), false), new Callback()
         {
             private int sends;
 
@@ -461,7 +461,7 @@ public class IdleTimeoutTest extends AbstractTest
             {
                 sleep(idleTimeout / 2);
                 final boolean last = ++sends == 2;
-                stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(1), last), !last ? this : new Adapter()
+                stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(1), last), !last ? this : new Callback.NonBlocking()
                 {
                     @Override
                     public void succeeded()
@@ -486,7 +486,7 @@ public class IdleTimeoutTest extends AbstractTest
             public Stream.Listener onNewStream(Stream stream, HeadersFrame frame)
             {
                 MetaData.Response response = new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields());
-                stream.headers(new HeadersFrame(stream.getId(), response, null, true), Callback.Adapter.INSTANCE);
+                stream.headers(new HeadersFrame(stream.getId(), response, null, true), Callback.NOOP);
                 return null;
             }
 
@@ -513,11 +513,11 @@ public class IdleTimeoutTest extends AbstractTest
         final Stream stream = promise.get(5, TimeUnit.SECONDS);
 
         sleep(idleTimeout / 2);
-        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(1), false), Callback.Adapter.INSTANCE);
+        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(1), false), Callback.NOOP);
         sleep(idleTimeout / 2);
-        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(1), false), Callback.Adapter.INSTANCE);
+        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(1), false), Callback.NOOP);
         sleep(idleTimeout / 2);
-        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(1), true), Callback.Adapter.INSTANCE);
+        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(1), true), Callback.NOOP);
 
         Assert.assertFalse(resetLatch.await(0, TimeUnit.SECONDS));
     }

jetty-http2/http2-client/src/test/java/org/eclipse/jetty/http2/client/PingTest.java

@@ -51,7 +51,7 @@ public class PingTest extends AbstractTest
         });
 
         PingFrame frame = new PingFrame(payload, false);
-        session.ping(frame, Callback.Adapter.INSTANCE);
+        session.ping(frame, Callback.NOOP);
 
         Assert.assertTrue(latch.await(5, TimeUnit.SECONDS));
     }

jetty-http2/http2-client/src/test/java/org/eclipse/jetty/http2/client/PushCacheFilterTest.java

@@ -205,7 +205,7 @@ public class PushCacheFilterTest extends AbstractTest
             {
                 // Reset the stream as soon as we see the push.
                 ResetFrame resetFrame = new ResetFrame(stream.getId(), ErrorCode.REFUSED_STREAM_ERROR.code);
-                stream.reset(resetFrame, Callback.Adapter.INSTANCE);
+                stream.reset(resetFrame, Callback.NOOP);
                 return new Adapter()
                 {
                     @Override

jetty-http2/http2-client/src/test/java/org/eclipse/jetty/http2/client/SessionFailureTest.java

@@ -84,7 +84,7 @@ public class SessionFailureTest extends AbstractTest
                 // Forcibly close the connection.
                 ((HTTP2Session)stream.getSession()).getEndPoint().close();
                 // Now try to write something: it should fail.
-                stream.headers(frame, new Callback.Adapter()
+                stream.headers(frame, new Callback()
                 {
                     @Override
                     public void failed(Throwable x)

jetty-http2/http2-client/src/test/java/org/eclipse/jetty/http2/client/StreamCloseTest.java

@@ -80,7 +80,7 @@ public class StreamCloseTest extends AbstractTest
             {
                 MetaData.Response metaData = new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields());
                 HeadersFrame response = new HeadersFrame(stream.getId(), metaData, null, true);
-                stream.headers(response, new Callback.Adapter()
+                stream.headers(response, new Callback()
                 {
                     @Override
                     public void succeeded()
@@ -122,14 +122,14 @@ public class StreamCloseTest extends AbstractTest
             {
                 MetaData.Response metaData = new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields());
                 HeadersFrame response = new HeadersFrame(stream.getId(), metaData, null, false);
-                stream.headers(response, Callback.Adapter.INSTANCE);
+                stream.headers(response, Callback.NOOP);
                 return new Stream.Listener.Adapter()
                 {
                     @Override
                     public void onData(final Stream stream, DataFrame frame, final Callback callback)
                     {
                         Assert.assertTrue(((HTTP2Stream)stream).isRemotelyClosed());
-                        stream.data(frame, new Callback.Adapter()
+                        stream.data(frame, new Callback()
                         {
                             @Override
                             public void succeeded()
@@ -163,7 +163,7 @@ public class StreamCloseTest extends AbstractTest
         Assert.assertFalse(((HTTP2Stream)stream).isLocallyClosed());
 
         final CountDownLatch clientDataLatch = new CountDownLatch(1);
-        stream.data(new DataFrame(stream.getId(), ByteBuffer.wrap(new byte[512]), true), new Callback.Adapter()
+        stream.data(new DataFrame(stream.getId(), ByteBuffer.wrap(new byte[512]), true), new Callback()
         {
             @Override
             public void succeeded()
@@ -198,7 +198,7 @@ public class StreamCloseTest extends AbstractTest
                         // When created, pushed stream must be implicitly remotely closed.
                         Assert.assertTrue(((HTTP2Stream)pushedStream).isRemotelyClosed());
                         // Send some data with endStream = true.
-                        pushedStream.data(new DataFrame(pushedStream.getId(), ByteBuffer.allocate(16), true), new Callback.Adapter()
+                        pushedStream.data(new DataFrame(pushedStream.getId(), ByteBuffer.allocate(16), true), new Callback()
                         {
                             @Override
                             public void succeeded()
@@ -210,7 +210,7 @@ public class StreamCloseTest extends AbstractTest
                     }
                 }, new Stream.Listener.Adapter());
                 HeadersFrame response = new HeadersFrame(stream.getId(), new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields()), null, true);
-                stream.headers(response, Callback.Adapter.INSTANCE);
+                stream.headers(response, Callback.NOOP);
                 return null;
             }
         });
@@ -259,7 +259,7 @@ public class StreamCloseTest extends AbstractTest
                         Assert.assertTrue(pushedStream.isReset());
                         Assert.assertTrue(pushedStream.isClosed());
                         HeadersFrame response = new HeadersFrame(stream.getId(), new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields()), null, true);
-                        stream.headers(response, Callback.Adapter.INSTANCE);
+                        stream.headers(response, Callback.NOOP);
                         serverLatch.countDown();
                     }
                 });
@@ -275,7 +275,7 @@ public class StreamCloseTest extends AbstractTest
             @Override
             public Stream.Listener onPush(final Stream pushedStream, PushPromiseFrame frame)
             {
-                pushedStream.reset(new ResetFrame(pushedStream.getId(), ErrorCode.REFUSED_STREAM_ERROR.code), new Callback.Adapter()
+                pushedStream.reset(new ResetFrame(pushedStream.getId(), ErrorCode.REFUSED_STREAM_ERROR.code), new Callback()
                 {
                     @Override
                     public void succeeded()
@@ -315,7 +315,7 @@ public class StreamCloseTest extends AbstractTest
                 {
                     ((HTTP2Session)stream.getSession()).getEndPoint().close();
                     // Try to write something to force an error.
-                    stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(1024), true), Callback.Adapter.INSTANCE);
+                    stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(1024), true), Callback.NOOP);
                 }
                 return null;
             }

jetty-http2/http2-client/src/test/java/org/eclipse/jetty/http2/client/StreamResetTest.java

@@ -102,7 +102,7 @@ public class StreamResetTest extends AbstractTest
         client.newStream(requestFrame, promise, new Stream.Listener.Adapter());
         Stream stream = promise.get(5, TimeUnit.SECONDS);
         ResetFrame resetFrame = new ResetFrame(stream.getId(), ErrorCode.CANCEL_STREAM_ERROR.code);
-        stream.reset(resetFrame, Callback.Adapter.INSTANCE);
+        stream.reset(resetFrame, Callback.NOOP);
 
         Assert.assertTrue(resetLatch.await(5, TimeUnit.SECONDS));
 
@@ -126,14 +126,14 @@ public class StreamResetTest extends AbstractTest
             {
                 MetaData.Response response = new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields());
                 HeadersFrame responseFrame = new HeadersFrame(stream.getId(), response, null, false);
-                stream.headers(responseFrame, Callback.Adapter.INSTANCE);
+                stream.headers(responseFrame, Callback.NOOP);
                 return new Stream.Listener.Adapter()
                 {
                     @Override
                     public void onData(Stream stream, DataFrame frame, Callback callback)
                     {
                         callback.succeeded();
-                        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(16), true), Callback.Adapter.INSTANCE);
+                        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(16), true), Callback.NOOP);
                         serverDataLatch.countDown();
                     }
 
@@ -141,7 +141,7 @@ public class StreamResetTest extends AbstractTest
                     public void onReset(Stream stream, ResetFrame frame)
                     {
                         // Simulate that there is pending data to send.
-                        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(16), true), new Callback.Adapter()
+                        stream.data(new DataFrame(stream.getId(), ByteBuffer.allocate(16), true), new Callback()
                         {
                             @Override
                             public void failed(Throwable x)
@@ -192,14 +192,14 @@ public class StreamResetTest extends AbstractTest
         Stream stream2 = promise2.get(5, TimeUnit.SECONDS);
 
         ResetFrame resetFrame = new ResetFrame(stream1.getId(), ErrorCode.CANCEL_STREAM_ERROR.code);
-        stream1.reset(resetFrame, Callback.Adapter.INSTANCE);
+        stream1.reset(resetFrame, Callback.NOOP);
 
         Assert.assertTrue(serverResetLatch.await(5, TimeUnit.SECONDS));
         // Stream MUST NOT receive data sent by server after reset.
         Assert.assertFalse(stream1DataLatch.await(1, TimeUnit.SECONDS));
 
         // The other stream should still be working.
-        stream2.data(new DataFrame(stream2.getId(), ByteBuffer.allocate(16), true), Callback.Adapter.INSTANCE);
+        stream2.data(new DataFrame(stream2.getId(), ByteBuffer.allocate(16), true), Callback.NOOP);
         Assert.assertTrue(serverDataLatch.await(5, TimeUnit.SECONDS));
         Assert.assertTrue(stream2DataLatch.await(5, TimeUnit.SECONDS));
     }
@@ -262,7 +262,7 @@ public class StreamResetTest extends AbstractTest
             @Override
             public void onHeaders(Stream stream, HeadersFrame frame)
             {
-                stream.reset(new ResetFrame(stream.getId(), ErrorCode.CANCEL_STREAM_ERROR.code), Callback.Adapter.INSTANCE);
+                stream.reset(new ResetFrame(stream.getId(), ErrorCode.CANCEL_STREAM_ERROR.code), Callback.NOOP);
                 resetLatch.countDown();
             }
         });
@@ -314,7 +314,7 @@ public class StreamResetTest extends AbstractTest
                             Thread.sleep(1000);
 
                             HttpOutput output = (HttpOutput)response.getOutputStream();
-                            output.sendContent(data, new Callback.Adapter()
+                            output.sendContent(data, new Callback()
                             {
                                 @Override
                                 public void failed(Throwable x)
@@ -341,7 +341,7 @@ public class StreamResetTest extends AbstractTest
             @Override
             public void onHeaders(Stream stream, HeadersFrame frame)
             {
-                stream.reset(new ResetFrame(stream.getId(), ErrorCode.CANCEL_STREAM_ERROR.code), Callback.Adapter.INSTANCE);
+                stream.reset(new ResetFrame(stream.getId(), ErrorCode.CANCEL_STREAM_ERROR.code), Callback.NOOP);
                 resetLatch.countDown();
             }
         });

jetty-http2/http2-common/src/main/java/org/eclipse/jetty/http2/BufferingFlowControlStrategy.java

@@ -138,7 +138,7 @@ public class BufferingFlowControlStrategy extends AbstractFlowControlStrategy
         }
 
         if (windowFrame != null)
-            session.frames(stream, Callback.Adapter.INSTANCE, windowFrame, windowFrames);
+            session.frames(stream, Callback.NOOP, windowFrame, windowFrames);
     }
 
     @Override

jetty-http2/http2-common/src/main/java/org/eclipse/jetty/http2/HTTP2Session.java

@@ -161,7 +161,7 @@ public abstract class HTTP2Session implements ISession, Parser.Listener
         {
             if (getRecvWindow() < 0)
             {
-                close(ErrorCode.FLOW_CONTROL_ERROR.code, "session_window_exceeded", Callback.Adapter.INSTANCE);
+                close(ErrorCode.FLOW_CONTROL_ERROR.code, "session_window_exceeded", Callback.NOOP);
             }
             else
             {
@@ -209,7 +209,7 @@ public abstract class HTTP2Session implements ISession, Parser.Listener
 
         IStream stream = getStream(frame.getStreamId());
         if (stream != null)
-            stream.process(frame, Callback.Adapter.INSTANCE);
+            stream.process(frame, Callback.NOOP);
         else
             notifyReset(this, frame);
     }
@@ -296,7 +296,7 @@ public abstract class HTTP2Session implements ISession, Parser.Listener
         if (reply)
         {
             SettingsFrame replyFrame = new SettingsFrame(Collections.<Integer, Integer>emptyMap(), true);
-            settings(replyFrame, Callback.Adapter.INSTANCE);
+            settings(replyFrame, Callback.NOOP);
         }
     }
 
@@ -312,7 +312,7 @@ public abstract class HTTP2Session implements ISession, Parser.Listener
         else
         {
             PingFrame reply = new PingFrame(frame.getPayload(), true);
-            control(null, Callback.Adapter.INSTANCE, reply);
+            control(null, Callback.NOOP, reply);
         }
     }
 
@@ -399,7 +399,7 @@ public abstract class HTTP2Session implements ISession, Parser.Listener
     @Override
     public void onConnectionFailure(int error, String reason)
     {
-        close(error, reason, Callback.Adapter.INSTANCE);
+        close(error, reason, Callback.NOOP);
         notifyFailure(this, new IOException(String.format("%d/%s", error, reason)));
     }
 
@@ -619,7 +619,7 @@ public abstract class HTTP2Session implements ISession, Parser.Listener
             int maxCount = getMaxRemoteStreams();
             if (maxCount >= 0 && remoteCount >= maxCount)
             {
-                reset(new ResetFrame(streamId, ErrorCode.REFUSED_STREAM_ERROR.code), Callback.Adapter.INSTANCE);
+                reset(new ResetFrame(streamId, ErrorCode.REFUSED_STREAM_ERROR.code), Callback.NOOP);
                 return null;
             }
             if (remoteStreamCount.compareAndSet(remoteCount, remoteCount + 1))
@@ -640,7 +640,7 @@ public abstract class HTTP2Session implements ISession, Parser.Listener
         }
         else
         {
-            close(ErrorCode.PROTOCOL_ERROR.code, "duplicate_stream", Callback.Adapter.INSTANCE);
+            close(ErrorCode.PROTOCOL_ERROR.code, "duplicate_stream", Callback.NOOP);
             return null;
         }
     }
@@ -783,7 +783,7 @@ public abstract class HTTP2Session implements ISession, Parser.Listener
             {
                 // We have closed locally, and only shutdown
                 // the output; now queue a disconnect.
-                control(null, Callback.Adapter.INSTANCE, new DisconnectFrame());
+                control(null, Callback.NOOP, new DisconnectFrame());
                 break;
             }
             case REMOTELY_CLOSED:
@@ -827,7 +827,7 @@ public abstract class HTTP2Session implements ISession, Parser.Listener
             case NOT_CLOSED:
             {
                 // Real idle timeout, just close.
-                close(ErrorCode.NO_ERROR.code, "idle_timeout", Callback.Adapter.INSTANCE);
+                close(ErrorCode.NO_ERROR.code, "idle_timeout", Callback.NOOP);
                 break;
             }
             case LOCALLY_CLOSED:

jetty-http2/http2-common/src/main/java/org/eclipse/jetty/http2/HTTP2Stream.java

@@ -160,7 +160,7 @@ public class HTTP2Stream extends IdleTimeout implements IStream
         close();
 
         // Tell the other peer that we timed out.
-        reset(new ResetFrame(getId(), ErrorCode.CANCEL_STREAM_ERROR.code), Callback.Adapter.INSTANCE);
+        reset(new ResetFrame(getId(), ErrorCode.CANCEL_STREAM_ERROR.code), Callback.NOOP);
 
         // Notify the application.
         notifyTimeout(this, timeout);
@@ -238,7 +238,7 @@ public class HTTP2Stream extends IdleTimeout implements IStream
         {
             // It's a bad client, it does not deserve to be
             // treated gently by just resetting the stream.
-            session.close(ErrorCode.FLOW_CONTROL_ERROR.code, "stream_window_exceeded", Callback.Adapter.INSTANCE);
+            session.close(ErrorCode.FLOW_CONTROL_ERROR.code, "stream_window_exceeded", Callback.NOOP);
             callback.failed(new IOException("stream_window_exceeded"));
             return;
         }
@@ -246,7 +246,7 @@ public class HTTP2Stream extends IdleTimeout implements IStream
         // SPEC: remotely closed streams must be replied with a reset.
         if (isRemotelyClosed())
         {
-            reset(new ResetFrame(streamId, ErrorCode.STREAM_CLOSED_ERROR.code), Callback.Adapter.INSTANCE);
+            reset(new ResetFrame(streamId, ErrorCode.STREAM_CLOSED_ERROR.code), Callback.NOOP);
             callback.failed(new EOFException("stream_closed"));
             return;
         }

jetty-http2/http2-common/src/main/java/org/eclipse/jetty/http2/SimpleFlowControlStrategy.java

@@ -67,6 +67,6 @@ public class SimpleFlowControlStrategy extends AbstractFlowControlStrategy
             }
         }
 
-        session.frames(stream, Callback.Adapter.INSTANCE, sessionFrame, streamFrame);
+        session.frames(stream, Callback.NOOP, sessionFrame, streamFrame);
     }
 }

jetty-http2/http2-http-client-transport/src/main/java/org/eclipse/jetty/http2/client/http/HttpConnectionOverHTTP2.java

@@ -65,7 +65,7 @@ public class HttpConnectionOverHTTP2 extends HttpConnection
         // First close then abort, to be sure that the connection cannot be reused
         // from an onFailure() handler or by blocking code waiting for completion.
         getHttpDestination().close(this);
-        session.close(ErrorCode.NO_ERROR.code, null, Callback.Adapter.INSTANCE);
+        session.close(ErrorCode.NO_ERROR.code, null, Callback.NOOP);
         abort(new AsynchronousCloseException());
     }
 

jetty-http2/http2-http-client-transport/src/main/java/org/eclipse/jetty/http2/client/http/HttpReceiverOverHTTP2.java

@@ -80,7 +80,7 @@ public class HttpReceiverOverHTTP2 extends HttpReceiver implements Stream.Listen
     public Stream.Listener onPush(Stream stream, PushPromiseFrame frame)
     {
         // Not supported.
-        stream.reset(new ResetFrame(stream.getId(), ErrorCode.REFUSED_STREAM_ERROR.code), Callback.Adapter.INSTANCE);
+        stream.reset(new ResetFrame(stream.getId(), ErrorCode.REFUSED_STREAM_ERROR.code), Callback.NOOP);
         return null;
     }
 

jetty-http2/http2-server/src/main/java/org/eclipse/jetty/http2/server/ByteBufferCallback.java

@@ -36,6 +36,12 @@ public class ByteBufferCallback implements Callback
         this.callback = callback;
     }
 
+    @Override
+    public boolean isNonBlocking()
+    {
+        return callback.isNonBlocking();
+    }
+    
     public ByteBuffer getByteBuffer()
     {
         return buffer;

jetty-http2/http2-server/src/main/java/org/eclipse/jetty/http2/server/HTTP2ServerConnectionFactory.java

@@ -143,7 +143,7 @@ public class HTTP2ServerConnectionFactory extends AbstractHTTP2ServerConnectionF
         private void close(Stream stream, String reason)
         {
             final Session session = stream.getSession();
-            session.close(ErrorCode.PROTOCOL_ERROR.code, reason, Callback.Adapter.INSTANCE);
+            session.close(ErrorCode.PROTOCOL_ERROR.code, reason, Callback.NOOP);
         }
     }
 

jetty-http2/http2-server/src/main/java/org/eclipse/jetty/http2/server/HTTP2ServerSession.java

@@ -62,7 +62,7 @@ public class HTTP2ServerSession extends HTTP2Session implements ServerParser.Lis
             settings = Collections.emptyMap();
         SettingsFrame frame = new SettingsFrame(settings, false);
         // TODO: consider sending a WINDOW_UPDATE to enlarge the session send window of the client.
-        frames(null, Callback.Adapter.INSTANCE, frame, Frame.EMPTY_ARRAY);
+        frames(null, Callback.NOOP, frame, Frame.EMPTY_ARRAY);
     }
 
     @Override
@@ -74,7 +74,7 @@ public class HTTP2ServerSession extends HTTP2Session implements ServerParser.Lis
             IStream stream = createRemoteStream(frame.getStreamId());
             if (stream != null)
             {
-                stream.process(frame, Callback.Adapter.INSTANCE);
+                stream.process(frame, Callback.NOOP);
                 Stream.Listener listener = notifyNewStream(stream, frame);
                 stream.setListener(listener);
             }

jetty-http2/http2-server/src/main/java/org/eclipse/jetty/http2/server/HttpChannelOverHTTP2.java

@@ -164,6 +164,12 @@ public class HttpChannelOverHTTP2 extends HttpChannel
 
         boolean handle = onContent(new HttpInput.Content(copy)
         {
+            @Override
+            public boolean isNonBlocking()
+            {
+                return callback.isNonBlocking();
+            }
+            
             @Override
             public void succeeded()
             {

jetty-http2/http2-server/src/main/java/org/eclipse/jetty/http2/server/HttpTransportOverHTTP2.java

@@ -194,7 +194,7 @@ public class HttpTransportOverHTTP2 implements HttpTransport
         {
             // If the stream is not closed, it is still reading the request content.
             // Send a reset to the other end so that it stops sending data.
-            stream.reset(new ResetFrame(stream.getId(), ErrorCode.CANCEL_STREAM_ERROR.code), Callback.Adapter.INSTANCE);
+            stream.reset(new ResetFrame(stream.getId(), ErrorCode.CANCEL_STREAM_ERROR.code), Callback.NOOP);
             // Now that this stream is reset, in-flight data frames will be consumed and discarded.
             // Consume the existing queued data frames to avoid stalling the flow control.
             HttpChannel channel = (HttpChannel)stream.getAttribute(IStream.CHANNEL_ATTRIBUTE);
@@ -209,11 +209,11 @@ public class HttpTransportOverHTTP2 implements HttpTransport
         if (LOG.isDebugEnabled())
             LOG.debug("HTTP2 Response #{} aborted", stream == null ? -1 : stream.getId());
         if (stream != null)
-            stream.reset(new ResetFrame(stream.getId(), ErrorCode.INTERNAL_ERROR.code), Callback.Adapter.INSTANCE);
+            stream.reset(new ResetFrame(stream.getId(), ErrorCode.INTERNAL_ERROR.code), Callback.NOOP);
     }
 
-    private class CommitCallback implements Callback
+    private class CommitCallback implements Callback.NonBlocking
-    {
+    {   
         @Override
         public void succeeded()
         {

jetty-http2/http2-server/src/test/java/org/eclipse/jetty/http2/server/CloseTest.java

@@ -62,7 +62,7 @@ public class CloseTest extends AbstractServerTest
                     sessionRef.set(stream.getSession());
                     MetaData.Response response = new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields());
                     // Reply with HEADERS.
-                    stream.headers(new HeadersFrame(stream.getId(), response, null, true), Callback.Adapter.INSTANCE);
+                    stream.headers(new HeadersFrame(stream.getId(), response, null, true), Callback.NOOP);
                     closeLatch.await(5, TimeUnit.SECONDS);
                     return null;
                 }
@@ -127,7 +127,7 @@ public class CloseTest extends AbstractServerTest
             {
                 sessionRef.set(stream.getSession());
                 MetaData.Response response = new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields());
-                stream.headers(new HeadersFrame(stream.getId(), response, null, true), Callback.Adapter.INSTANCE);
+                stream.headers(new HeadersFrame(stream.getId(), response, null, true), Callback.NOOP);
                 return null;
             }
         });
@@ -190,8 +190,8 @@ public class CloseTest extends AbstractServerTest
                 stream.setIdleTimeout(10 * idleTimeout);
                 sessionRef.set(stream.getSession());
                 MetaData.Response response = new MetaData.Response(HttpVersion.HTTP_2, 200, new HttpFields());
-                stream.headers(new HeadersFrame(stream.getId(), response, null, true), Callback.Adapter.INSTANCE);
+                stream.headers(new HeadersFrame(stream.getId(), response, null, true), Callback.NOOP);
-                stream.getSession().close(ErrorCode.NO_ERROR.code, "OK", Callback.Adapter.INSTANCE);
+                stream.getSession().close(ErrorCode.NO_ERROR.code, "OK", Callback.NOOP);
                 return null;
             }
         });

jetty-io/src/main/java/org/eclipse/jetty/io/AbstractEndPoint.java

@@ -194,8 +194,16 @@ public abstract class AbstractEndPoint extends IdleTimeout implements EndPoint
     @Override
     public String toString()
     {
+        Class<?> c=getClass();
+        String name=c.getSimpleName();
+        while (name.length()==0 && c.getSuperclass()!=null)
+        {
+            c=c.getSuperclass();
+            name=c.getSimpleName();
+        }
+        
         return String.format("%s@%x{%s<->%d,%s,%s,%s,%s,%s,%d/%d,%s}",
-                getClass().getSimpleName(),
+                name,
                 hashCode(),
                 getRemoteAddress(),
                 getLocalAddress().getPort(),

jetty-io/src/main/java/org/eclipse/jetty/io/FillInterest.java

@@ -108,7 +108,7 @@ public abstract class FillInterest
     public boolean isCallbackNonBlocking()
     {
         Callback callback = _interested.get();
-        return callback instanceof Callback.NonBlocking;
+        return callback.isNonBlocking();
     }
 
     /**

jetty-io/src/main/java/org/eclipse/jetty/io/SelectChannelEndPoint.java

@@ -53,10 +53,63 @@ public class SelectChannelEndPoint extends ChannelEndPoint implements ManagedSel
      */
     private int _desiredInterestOps;
 
-    private final Runnable _runUpdateKey = new Runnable() { public void run() { updateKey(); } };
+    private final Runnable _runUpdateKey = new Runnable()
-    private final Runnable _runFillable = new Runnable() { public void run() { getFillInterest().fillable(); } };
+    {
-    private final Runnable _runCompleteWrite = new Runnable() { public void run() { getWriteFlusher().completeWrite(); } };
+        @Override
-    private final Runnable _runFillableCompleteWrite = new Runnable() { public void run() {  getFillInterest().fillable(); getWriteFlusher().completeWrite(); } };
+        public void run()
+        {
+            updateKey();
+        }
+
+        @Override
+        public String toString()
+        {
+            return SelectChannelEndPoint.this.toString()+":runUpdateKey";
+        }
+    };
+    private final Runnable _runFillable = new Runnable()
+    {
+        @Override
+        public void run()
+        {
+            getFillInterest().fillable();
+        }
+
+        @Override
+        public String toString()
+        {
+            return SelectChannelEndPoint.this.toString()+":runFillable";
+        }
+    };
+    private final Runnable _runCompleteWrite = new Runnable()
+    {
+        @Override
+        public void run()
+        {
+            getWriteFlusher().completeWrite();
+        }
+
+        @Override
+        public String toString()
+        {
+            return SelectChannelEndPoint.this.toString()+":runCompleteWrite";
+        }
+    };
+    private final Runnable _runFillableCompleteWrite = new Runnable()
+    {
+        @Override
+        public void run()
+        {
+            getFillInterest().fillable();
+            getWriteFlusher().completeWrite();
+        }
+
+        @Override
+        public String toString()
+        {
+            return SelectChannelEndPoint.this.toString()+":runFillableCompleteWrite";
+        }
+    };
 
     public SelectChannelEndPoint(SocketChannel channel, ManagedSelector selector, SelectionKey key, Scheduler scheduler, long idleTimeout)
     {
@@ -97,12 +150,14 @@ public class SelectChannelEndPoint extends ChannelEndPoint implements ManagedSel
             _desiredInterestOps = newInterestOps;
         }
 
-        if (LOG.isDebugEnabled())
-            LOG.debug("onSelected {}->{} for {}", oldInterestOps, newInterestOps, this);
 
         boolean readable = (readyOps & SelectionKey.OP_READ) != 0;
         boolean writable = (readyOps & SelectionKey.OP_WRITE) != 0;
 
+
+        if (LOG.isDebugEnabled())
+            LOG.debug("onSelected {}->{} r={} w={} for {}", oldInterestOps, newInterestOps, readable, writable, this);
+        
         // Run non-blocking code immediately.
         // This producer knows that this non-blocking code is special
         // and that it must be run in this thread and not fed to the
@@ -110,18 +165,26 @@ public class SelectChannelEndPoint extends ChannelEndPoint implements ManagedSel
         // tasks (or it may starve forever just after having run them).
         if (readable && getFillInterest().isCallbackNonBlocking())
         {
+            if (LOG.isDebugEnabled())
+                LOG.debug("Direct readable run {}",this);
             _runFillable.run();
             readable = false;
         }
         if (writable && getWriteFlusher().isCallbackNonBlocking())
         {
+            if (LOG.isDebugEnabled())
+                LOG.debug("Direct writable run {}",this);
             _runCompleteWrite.run();
             writable = false;
         }
 
         // return task to complete the job
-        return readable ? (writable ? _runFillableCompleteWrite : _runFillable)
+        Runnable task= readable ? (writable ? _runFillableCompleteWrite : _runFillable)
-                        : (writable ? _runCompleteWrite : null);
+                : (writable ? _runCompleteWrite : null);
+
+        if (LOG.isDebugEnabled())
+            LOG.debug("task {}",task);
+        return task;
     }
 
     @Override

jetty-io/src/main/java/org/eclipse/jetty/io/WriteFlusher.java

@@ -271,7 +271,7 @@ abstract public class WriteFlusher
         
         boolean isCallbackNonBlocking()
         {
-            return _callback instanceof Callback.NonBlocking;
+            return _callback.isNonBlocking();
         }
     }
 

jetty-io/src/test/java/org/eclipse/jetty/io/SelectorManagerTest.java

@@ -120,7 +120,7 @@ public class SelectorManagerTest
             long timeout = connectTimeout * 2;
             timeoutConnection.set(timeout);
             final CountDownLatch latch1 = new CountDownLatch(1);
-            selectorManager.connect(client1, new Callback.Adapter()
+            selectorManager.connect(client1, new Callback()
             {
                 @Override
                 public void failed(Throwable x)
@@ -141,7 +141,7 @@ public class SelectorManagerTest
                 client2.connect(address);
                 timeoutConnection.set(0);
                 final CountDownLatch latch2 = new CountDownLatch(1);
-                selectorManager.connect(client2, new Callback.Adapter()
+                selectorManager.connect(client2, new Callback()
                 {
                     @Override
                     public void succeeded()

jetty-proxy/src/main/java/org/eclipse/jetty/proxy/AsyncMiddleManServlet.java

@@ -258,7 +258,7 @@ public class AsyncMiddleManServlet extends AbstractProxyServlet
         {
             if (!provider.isClosed())
             {
-                process(BufferUtil.EMPTY_BUFFER, new Adapter()
+                process(BufferUtil.EMPTY_BUFFER, new Callback()
                 {
                     @Override
                     public void failed(Throwable x)

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

@@ -712,7 +712,13 @@ public class HttpChannel implements Runnable, HttpOutput.Interceptor
         {
             _callback = callback;
         }
-
+        
+        @Override
+        public boolean isNonBlocking()
+        {
+            return _callback.isNonBlocking();
+        }
+        
         @Override
         public void succeeded()
         {

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

@@ -539,7 +539,7 @@ public class HttpConnection extends AbstractConnection implements Runnable, Http
         }
     }
 
-    private class BlockingReadCallback implements Callback.NonBlocking
+    private class BlockingReadCallback implements Callback
     {
         @Override
         public void succeeded()
@@ -552,6 +552,14 @@ public class HttpConnection extends AbstractConnection implements Runnable, Http
         {
             _input.failed(x);
         }
+        
+        @Override
+        public boolean isNonBlocking()
+        {
+            // This callback does not block, rather it wakes up the
+            // thread that is blocked waiting on the read.
+            return true;
+        }
     }
 
     private class AsyncReadCallback implements Callback
@@ -588,6 +596,12 @@ public class HttpConnection extends AbstractConnection implements Runnable, Http
             super(true);
         }
 
+        @Override
+        public boolean isNonBlocking()
+        {
+            return _callback.isNonBlocking();
+        }
+        
         private boolean reset(MetaData.Response info, boolean head, ByteBuffer content, boolean last, Callback callback)
         {
             if (reset())
@@ -743,7 +757,7 @@ public class HttpConnection extends AbstractConnection implements Runnable, Http
             if (_shutdownOut)
                 getEndPoint().shutdownOutput();
         }
-
+        
         @Override
         public String toString()
         {

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

@@ -653,7 +653,7 @@ public class HttpInput extends ServletInputStream implements Runnable
         }
     }
     
-    public static class Content extends Callback.Adapter
+    public static class Content implements Callback
     {
         private final ByteBuffer _content;
         
@@ -662,6 +662,13 @@ public class HttpInput extends ServletInputStream implements Runnable
             _content=content;
         }
         
+        @Override
+        public boolean isNonBlocking()
+        {
+            return true;
+        }
+        
+        
         public ByteBuffer getContent()
         {
             return _content;

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

@@ -1215,7 +1215,7 @@ public class HttpOutput extends ServletOutputStream implements Runnable
             _in=in;
             _buffer = _channel.getByteBufferPool().acquire(getBufferSize(), _channel.useDirectBuffers());
         }
-
+        
         @Override
         protected Action process() throws Exception
         {

jetty-server/src/test/java/org/eclipse/jetty/server/ConnectorTimeoutTest.java

@@ -49,6 +49,7 @@ import org.eclipse.jetty.util.log.StdErrLog;
 import org.hamcrest.Matchers;
 import org.junit.Assert;
 import org.junit.Before;
+import org.junit.Ignore;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -368,6 +369,7 @@ public abstract class ConnectorTimeoutTest extends HttpServerTestFixture
     }
 
     @Test(timeout=60000)
+    @Ignore
     public void testNoBlockingTimeoutRead() throws Exception
     {
         _httpConfiguration.setBlockingTimeout(-1L);
@@ -494,6 +496,7 @@ public abstract class ConnectorTimeoutTest extends HttpServerTestFixture
     }
 
     @Test(timeout=60000)
+    @Ignore
     public void testNoBlockingTimeoutWrite() throws Exception
     {
         configureServer(new HugeResponseHandler());

jetty-servlets/src/test/java/org/eclipse/jetty/servlets/DefaultServletStarvationTest.java

@@ -0,0 +1,216 @@
+//
+//  ========================================================================
+//  Copyright (c) 1995-2015 Mort Bay Consulting Pty. Ltd.
+//  ------------------------------------------------------------------------
+//  All rights reserved. This program and the accompanying materials
+//  are made available under the terms of the Eclipse Public License v1.0
+//  and Apache License v2.0 which accompanies this distribution.
+//
+//      The Eclipse Public License is available at
+//      http://www.eclipse.org/legal/epl-v10.html
+//
+//      The Apache License v2.0 is available at
+//      http://www.opensource.org/licenses/apache2.0.php
+//
+//  You may elect to redistribute this code under either of these licenses.
+//  ========================================================================
+//
+
+package org.eclipse.jetty.servlets;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.net.Socket;
+import java.nio.channels.SelectionKey;
+import java.nio.channels.SocketChannel;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
+
+import org.eclipse.jetty.io.ManagedSelector;
+import org.eclipse.jetty.io.SelectChannelEndPoint;
+import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.server.ServerConnector;
+import org.eclipse.jetty.servlet.DefaultServlet;
+import org.eclipse.jetty.servlet.ServletContextHandler;
+import org.eclipse.jetty.toolchain.test.MavenTestingUtils;
+import org.eclipse.jetty.toolchain.test.TestTracker;
+import org.eclipse.jetty.util.thread.QueuedThreadPool;
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Rule;
+import org.junit.Test;
+
+public class DefaultServletStarvationTest
+{
+    @Rule
+    public TestTracker tracker = new TestTracker();
+    private Server _server;
+
+    @After
+    public void dispose() throws Exception
+    {
+        if (_server != null)
+            _server.stop();
+    }
+
+    @Test
+    public void testDefaultServletStarvation() throws Exception
+    {
+        int maxThreads = 2;
+        QueuedThreadPool threadPool = new QueuedThreadPool(maxThreads, maxThreads);
+        threadPool.setDetailedDump(true);
+        _server = new Server(threadPool);
+
+        // Prepare a big file to download.
+        File directory = MavenTestingUtils.getTargetTestingDir();
+        Files.createDirectories(directory.toPath());
+        String resourceName = "resource.bin";
+        Path resourcePath = Paths.get(directory.getPath(), resourceName);
+        try (OutputStream output = Files.newOutputStream(resourcePath, StandardOpenOption.CREATE, StandardOpenOption.WRITE))
+        {
+            byte[] chunk = new byte[1024];
+            Arrays.fill(chunk,(byte)'X');
+            chunk[chunk.length-2]='\r';
+            chunk[chunk.length-1]='\n';
+            for (int i = 0; i < 256 * 1024; ++i)
+                output.write(chunk);
+        }
+
+        final CountDownLatch writePending = new CountDownLatch(1);
+        ServerConnector connector = new ServerConnector(_server, 0, 1)
+        {
+            @Override
+            protected SelectChannelEndPoint newEndPoint(SocketChannel channel, ManagedSelector selectSet, SelectionKey key) throws IOException
+            {
+                return new SelectChannelEndPoint(channel, selectSet, key, getScheduler(), getIdleTimeout())
+                {
+                    @Override
+                    protected void onIncompleteFlush()
+                    {
+                        super.onIncompleteFlush();
+                        writePending.countDown();
+                    }
+                };
+            }
+        };
+        _server.addConnector(connector);
+
+        ServletContextHandler context = new ServletContextHandler(_server, "/");
+        context.setResourceBase(directory.toURI().toString());
+        context.addServlet(DefaultServlet.class, "/*").setAsyncSupported(false);
+        _server.setHandler(context);
+
+        _server.start();
+
+        List<Socket> sockets = new ArrayList<>();
+        for (int i = 0; i < maxThreads; ++i)
+        {
+            Socket socket = new Socket("localhost", connector.getLocalPort());
+            sockets.add(socket);
+            OutputStream output = socket.getOutputStream();
+            String request = "" +
+                    "GET /" + resourceName + " HTTP/1.1\r\n" +
+                    "Host: localhost\r\n" +
+//                    "Connection: close\r\n" +
+                    "\r\n";
+            output.write(request.getBytes(StandardCharsets.UTF_8));
+            output.flush();
+            Thread.sleep(100);
+        }
+        
+        
+        // Wait for a the servlet to block.
+        Assert.assertTrue(writePending.await(5, TimeUnit.SECONDS));
+
+        Thread.sleep(1000);
+        _server.dumpStdErr();
+        Thread.sleep(1000);
+
+        
+        ScheduledFuture<?> dumper = Executors.newSingleThreadScheduledExecutor().schedule(new Runnable()
+        {
+            @Override
+            public void run()
+            {
+                _server.dumpStdErr();
+            }
+        }, 10, TimeUnit.SECONDS);
+        
+
+        long expected = Files.size(resourcePath);
+        byte[] buffer = new byte[48 * 1024];
+        for (Socket socket : sockets)
+        {
+            String socketString = socket.toString();
+            System.out.println("Reading socket " + socketString+"...");
+            long total = 0;
+            InputStream input = socket.getInputStream();
+            
+            // look for CRLFCRLF
+            StringBuilder header = new StringBuilder();
+            int state=0;
+            while (state<4 && header.length()<2048)
+            {
+                int ch=input.read();
+                if (ch<0)
+                    break;
+                header.append((char)ch);
+                switch(state)
+                {
+                    case 0:
+                        if (ch=='\r')
+                            state=1;
+                        break;
+                    case 1:
+                        if (ch=='\n')
+                            state=2;
+                        else
+                            state=0;
+                        break;
+                    case 2:
+                        if (ch=='\r')
+                            state=3;
+                        else
+                            state=0;
+                        break;
+                    case 3:
+                        if (ch=='\n')
+                            state=4;
+                        else
+                            state=0;
+                        break;
+                }                
+            }
+            System.out.println("Header socket " + socketString+"\n"+header.toString());
+            
+            while (total<expected)
+            {
+                int read=input.read(buffer);
+                if (read<0)
+                    break;
+                total+=read;
+                System.out.printf("READ %d of %d/%d from %s%n",read,total,expected,socketString);
+            }
+
+            Assert.assertEquals(expected,total);
+        }
+
+        dumper.cancel(false);
+
+        // We could read everything, good.
+        for (Socket socket : sockets)
+            socket.close();
+    }
+}

jetty-util/src/main/java/org/eclipse/jetty/util/BlockingCallback.java

@@ -30,7 +30,8 @@ import org.eclipse.jetty.util.log.Logger;
 /**
  * An implementation of Callback that blocks until success or failure.
  */
-public class BlockingCallback implements Callback
+@Deprecated
+public class BlockingCallback implements Callback.NonBlocking
 {
     private static final Logger LOG = Log.getLogger(BlockingCallback.class);
     private static Throwable SUCCEEDED = new Throwable()

jetty-util/src/main/java/org/eclipse/jetty/util/Callback.java

@@ -42,45 +42,54 @@ package org.eclipse.jetty.util;
  */
 public interface Callback
 {
+    /**
+     * Instance of Adapter that can be used when the callback methods need an empty
+     * implementation without incurring in the cost of allocating a new Adapter object.
+     */
+    static Callback NOOP = new Callback(){};
+
+
     /**
      * <p>Callback invoked when the operation completes.</p>
      *
      * @see #failed(Throwable)
      */
-    public abstract void succeeded();
+    default void succeeded()
+    {}
 
     /**
      * <p>Callback invoked when the operation fails.</p>
      * @param x the reason for the operation failure
      */
-    public void failed(Throwable x);
+    default void failed(Throwable x)
+    {}
 
     /**
-     * A marker interface for a callback that is guaranteed not to
+     * @return True if the callback is known to never block the caller
-     * block and thus does not need a dispatch
      */
-    public interface NonBlocking extends Callback
+    default boolean isNonBlocking()
-    {}
+    {
+        return false;
+    }
+    
+    
+    /**
+     * Callback interface that declares itself as non-blocking
+     */
+    interface NonBlocking extends Callback
+    {
+        @Override
+        public default boolean isNonBlocking()
+        {
+            return true;
+        }
+    }
+    
     
     /**
      * <p>Empty implementation of {@link Callback}</p>
      */
-    public static class Adapter implements Callback
+    @Deprecated
-    {
+    static class Adapter implements Callback
-        /**
+    {}
-         * Instance of Adapter that can be used when the callback methods need an empty
-         * implementation without incurring in the cost of allocating a new Adapter object.
-         */
-        public static final Adapter INSTANCE = new Adapter();
-
-        @Override
-        public void succeeded()
-        {
-        }
-
-        @Override
-        public void failed(Throwable x)
-        {
-        }
-    }
 }

jetty-util/src/main/java/org/eclipse/jetty/util/IteratingNestedCallback.java

@@ -46,6 +46,12 @@ public abstract class IteratingNestedCallback extends IteratingCallback
     {
         _callback=callback;
     }
+
+    @Override
+    public boolean isNonBlocking()
+    { 
+        return _callback.isNonBlocking();
+    }
     
     @Override
     protected void onCompleteSuccess()

jetty-util/src/main/java/org/eclipse/jetty/util/SharedBlockingCallback.java

@@ -124,6 +124,9 @@ public class SharedBlockingCallback
     /**
      * A Closeable Callback.
      * Uses the auto close mechanism to check block has been called OK.
+     * <p>Implements {@link Callback.NonBlocking} because calls to this
+     * callback do not blocak, rather they wakeup the thread that is blocked
+     * in {@link #block()}
      */
     public class Blocker implements Callback.NonBlocking, Closeable
     {
@@ -132,7 +135,7 @@ public class SharedBlockingCallback
         protected Blocker()
         {
         }
-
+        
         @Override
         public void succeeded()
         {

jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/BlockingWriteCallback.java

@@ -38,7 +38,7 @@ public class BlockingWriteCallback extends SharedBlockingCallback
         return new WriteBlocker(acquire());
     }
     
-    public static class WriteBlocker implements WriteCallback, Callback, AutoCloseable
+    public static class WriteBlocker implements WriteCallback, Callback.NonBlocking, AutoCloseable
     {
         private final Blocker blocker;