Synchronize message sending

Issue: SPR-12516
(backport for commit b796c1)

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/AbstractHttpSockJsSession.java

@@ -70,7 +70,7 @@ public abstract class AbstractHttpSockJsSession extends AbstractSockJsSession {
 
 	private final Object responseLock = new Object();
 
-	private volatile boolean requestInitialized;
+	private volatile boolean readyToSend;
 
 
 	private final Queue<String> messageCache;
@@ -195,18 +195,24 @@ public abstract class AbstractHttpSockJsSession extends AbstractSockJsSession {
 		this.localAddress = request.getLocalAddress();
 		this.remoteAddress = request.getRemoteAddress();
 
+		synchronized (this.responseLock) {
+			try {
 				this.response = response;
 				this.frameFormat = frameFormat;
 				this.asyncRequestControl = request.getAsyncRequestControl(response);
+				this.asyncRequestControl.start(-1);
 
-		synchronized (this.responseLock) {
-			try {
 				// Let "our" handler know before sending the open frame to the remote handler
 				delegateConnectionEstablished();
+
+				if (isStreaming()) {
 					writePrelude(request, response);
 					writeFrame(SockJsFrame.openFrame());
-				if (isStreaming() && !isClosed()) {
-					startAsyncRequest();
+					flushCache();
+					this.readyToSend = true;
+				}
+				else {
+					writeFrame(SockJsFrame.openFrame());
 				}
 			}
 			catch (Throwable ex) {
@@ -219,17 +225,6 @@ public abstract class AbstractHttpSockJsSession extends AbstractSockJsSession {
 	protected void writePrelude(ServerHttpRequest request, ServerHttpResponse response) throws IOException {
 	}
 
-	private void startAsyncRequest() {
-		this.asyncRequestControl.start(-1);
-		if (this.messageCache.size() > 0) {
-			flushCache();
-		}
-		else {
-			scheduleHeartbeat();
-		}
-		this.requestInitialized = true;
-	}
-
 	/**
 	 * Handle all requests, except the first one, to receive messages on a SockJS
 	 * HTTP transport based session.
@@ -249,12 +244,27 @@ public abstract class AbstractHttpSockJsSession extends AbstractSockJsSession {
 			try {
 				if (isClosed()) {
 					response.getBody().write(SockJsFrame.closeFrameGoAway().getContentBytes());
+					return;
 				}
 				this.response = response;
 				this.frameFormat = frameFormat;
 				this.asyncRequestControl = request.getAsyncRequestControl(response);
+				this.asyncRequestControl.start(-1);
+
+				if (isStreaming()) {
 					writePrelude(request, response);
-				startAsyncRequest();
+					flushCache();
+					this.readyToSend = true;
+				}
+				else {
+					if (this.messageCache.isEmpty()) {
+						scheduleHeartbeat();
+						this.readyToSend = true;
+					}
+					else {
+						flushCache();
+					}
+				}
 			}
 			catch (Throwable ex) {
 				tryCloseWithSockJsTransportError(ex, CloseStatus.SERVER_ERROR);
@@ -266,32 +276,24 @@ public abstract class AbstractHttpSockJsSession extends AbstractSockJsSession {
 
 	@Override
 	protected final void sendMessageInternal(String message) throws SockJsTransportFailureException {
-		this.messageCache.add(message);
-		tryFlushCache();
-	}
-
-	private boolean tryFlushCache() throws SockJsTransportFailureException {
 		synchronized (this.responseLock) {
-			if (this.messageCache.isEmpty()) {
-				logger.trace("Nothing to flush in session=" + this.getId());
-				return false;
-			}
+			this.messageCache.add(message);
 			if (logger.isTraceEnabled()) {
 				logger.trace(this.messageCache.size() + " message(s) to flush in session " + this.getId());
 			}
-			if (isActive() && this.requestInitialized) {
+			if (isActive() && this.readyToSend) {
 				if (logger.isTraceEnabled()) {
 					logger.trace("Session is active, ready to flush.");
 				}
 				cancelHeartbeat();
 				flushCache();
-				return true;
+				return;
 			}
 			else {
 				if (logger.isTraceEnabled()) {
 					logger.trace("Session is not active, not ready to flush.");
 				}
-				return false;
+				return;
 			}
 		}
 	}
@@ -312,7 +314,7 @@ public abstract class AbstractHttpSockJsSession extends AbstractSockJsSession {
 
 			ServerHttpAsyncRequestControl control = this.asyncRequestControl;
 			this.asyncRequestControl = null;
-			this.requestInitialized = false;
+			this.readyToSend = false;
 			this.response = null;
 
 			updateLastActiveTime();

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/StreamingSockJsSession.java

@@ -18,13 +18,9 @@ package org.springframework.web.socket.sockjs.transport.session;
 
 import java.util.Map;
 
-import org.springframework.http.server.ServerHttpRequest;
-import org.springframework.http.server.ServerHttpResponse;
 import org.springframework.web.socket.WebSocketHandler;
-import org.springframework.web.socket.sockjs.SockJsException;
 import org.springframework.web.socket.sockjs.SockJsTransportFailureException;
 import org.springframework.web.socket.sockjs.frame.SockJsFrame;
-import org.springframework.web.socket.sockjs.frame.SockJsFrameFormat;
 import org.springframework.web.socket.sockjs.frame.SockJsMessageCodec;
 import org.springframework.web.socket.sockjs.transport.SockJsServiceConfig;
 
@@ -53,7 +49,7 @@ public class StreamingSockJsSession extends AbstractHttpSockJsSession {
 
 	@Override
 	protected void flushCache() throws SockJsTransportFailureException {
-		do {
+		while (!getMessageCache().isEmpty()) {
 			String message = getMessageCache().poll();
 			SockJsMessageCodec messageCodec = getSockJsServiceConfig().getMessageCodec();
 			SockJsFrame frame = SockJsFrame.messageFrame(messageCodec, message);
@@ -73,7 +69,6 @@ public class StreamingSockJsSession extends AbstractHttpSockJsSession {
 				break;
 			}
 		}
-		while (!getMessageCache().isEmpty());
 		scheduleHeartbeat();
 	}
 

spring-websocket/src/test/java/org/springframework/web/socket/sockjs/transport/handler/HttpSendingTransportHandlerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,25 +16,27 @@
 
 package org.springframework.web.socket.sockjs.transport.handler;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Matchers.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+
 import java.sql.Date;
 
 import org.junit.Before;
 import org.junit.Test;
-
 import org.springframework.scheduling.TaskScheduler;
 import org.springframework.web.socket.AbstractHttpRequestTests;
 import org.springframework.web.socket.WebSocketHandler;
-import org.springframework.web.socket.sockjs.frame.SockJsFrameFormat;
 import org.springframework.web.socket.sockjs.frame.SockJsFrame;
+import org.springframework.web.socket.sockjs.frame.SockJsFrameFormat;
 import org.springframework.web.socket.sockjs.transport.session.AbstractSockJsSession;
 import org.springframework.web.socket.sockjs.transport.session.PollingSockJsSession;
 import org.springframework.web.socket.sockjs.transport.session.StreamingSockJsSession;
 import org.springframework.web.socket.sockjs.transport.session.StubSockJsServiceConfig;
 
-import static org.junit.Assert.*;
-import static org.mockito.Matchers.any;
-import static org.mockito.Mockito.*;
-
 /**
  * Test fixture for {@link AbstractHttpSendingTransportHandler} and sub-classes.
  *
@@ -75,7 +77,7 @@ public class HttpSendingTransportHandlerTests  extends AbstractHttpRequestTests
 		assertFalse("Polling request should complete after open frame", this.servletRequest.isAsyncStarted());
 		verify(this.webSocketHandler).afterConnectionEstablished(session);
 
-		resetResponse();
+		resetRequestAndResponse();
 		transportHandler.handleRequest(this.request, this.response, this.webSocketHandler, session);
 
 		assertTrue("Polling request should remain open", this.servletRequest.isAsyncStarted());

spring-websocket/src/test/java/org/springframework/web/socket/sockjs/transport/session/HttpSockJsSessionTests.java

@@ -82,7 +82,7 @@ public class HttpSockJsSessionTests extends AbstractSockJsSessionTests<TestAbstr
 		this.session.handleInitialRequest(this.request, this.response, this.frameFormat);
 
 		assertEquals("hhh\no", this.servletResponse.getContentAsString());
-		assertFalse(this.servletRequest.isAsyncStarted());
+		assertTrue(this.servletRequest.isAsyncStarted());
 
 		verify(this.webSocketHandler).afterConnectionEstablished(this.session);
 	}
@@ -119,7 +119,7 @@ public class HttpSockJsSessionTests extends AbstractSockJsSessionTests<TestAbstr
 
 		@Override
 		protected boolean isStreaming() {
-			return false;
+			return true;
 		}
 
 		@Override