Merge pull request #133 from violetagg/onwritepossible-concurrency

AbstractResponseBodySubscriber improvements

spring-web-reactive/src/main/java/org/springframework/http/server/reactive/AbstractResponseBodySubscriber.java

@@ -101,6 +101,16 @@ abstract class AbstractResponseBodySubscriber implements Subscriber<DataBuffer>
 	protected void receiveBuffer(DataBuffer dataBuffer) {
 		Assert.state(this.currentBuffer == null);
 		this.currentBuffer = dataBuffer;
+
+		checkOnWritePossible();
+	}
+
+	/**
+	 * Called when a {@link DataBuffer} is received via {@link Subscriber#onNext(Object)}
+	 * or when only partial data from the {@link DataBuffer} was written.
+	 */
+	protected void checkOnWritePossible() {
+		// no-op
 	}
 
 	/**
@@ -238,6 +248,7 @@ abstract class AbstractResponseBodySubscriber implements Subscriber<DataBuffer>
 						}
 						else {
 							subscriber.changeState(WRITING, RECEIVED);
+							subscriber.checkOnWritePossible(); 
 						}
 					}
 					catch (IOException ex) {

spring-web-reactive/src/main/java/org/springframework/http/server/reactive/ServletHttpHandlerAdapter.java

@@ -233,9 +233,7 @@ public class ServletHttpHandlerAdapter extends HttpServlet {
 		}
 
 		@Override
-		protected void receiveBuffer(DataBuffer dataBuffer) {
-			super.receiveBuffer(dataBuffer);
-
+		protected void checkOnWritePossible() {
 			try {
 				if (outputStream().isReady()) {
 					onWritePossible();