ReactorNettyWebSocketSession implements close properly

Issue: SPR-16774

spring-webflux/src/main/java/org/springframework/web/reactive/socket/adapter/ReactorNettyWebSocketSession.java

 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -15,10 +15,12 @@
  */
 package org.springframework.web.reactive.socket.adapter;
 
+import io.netty.handler.codec.http.websocketx.CloseWebSocketFrame;
 import io.netty.handler.codec.http.websocketx.WebSocketFrame;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
+import reactor.core.publisher.MonoProcessor;
 import reactor.ipc.netty.NettyInbound;
 import reactor.ipc.netty.NettyOutbound;
 import reactor.ipc.netty.NettyPipeline;
@@ -42,6 +44,8 @@ import org.springframework.web.reactive.socket.WebSocketSession;
 public class ReactorNettyWebSocketSession
 		extends NettyWebSocketSessionSupport<ReactorNettyWebSocketSession.WebSocketConnection> {
 
+	private final MonoProcessor<WebSocketFrame> closeMono = MonoProcessor.create();
+
 
 	public ReactorNettyWebSocketSession(WebsocketInbound inbound, WebsocketOutbound outbound,
 			HandshakeInfo info, NettyDataBufferFactory bufferFactory) {
@@ -69,11 +73,8 @@ public class ReactorNettyWebSocketSession
 
 	@Override
 	public Mono<Void> close(CloseStatus status) {
-		return Mono.error(new UnsupportedOperationException(
-				"Reactor Netty does not support closing the session from anywhere. " +
-						"You will need to work with the Flux returned from receive() method, " +
-						"either subscribing to it and using the returned Disposable, " +
-						"or using an operator that cancels (e.g. take)."));
+		WebSocketFrame closeFrame = new CloseWebSocketFrame(status.getCode(), status.getReason());
+		return getDelegate().getOutbound().sendObject(closeFrame).then();
 	}
 
 

spring-webflux/src/test/java/org/springframework/web/reactive/socket/WebSocketIntegrationTests.java

 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -127,6 +127,21 @@ public class WebSocketIntegrationTests extends AbstractWebSocketIntegrationTests
 		assertEquals("my-header:my-value", output.block(Duration.ofMillis(5000)));
 	}
 
+	@Test
+	public void sessionClosing() throws Exception {
+		this.client.execute(getUrl("/close"),
+				session -> {
+					logger.debug("Starting..");
+					return session.receive()
+							.doOnNext(s -> logger.debug("inbound " + s))
+							.then()
+							.doFinally(signalType -> {
+								logger.debug("Completed with: " + signalType);
+							});
+				})
+				.block(Duration.ofMillis(5000));
+	}
+
 
 	@Configuration
 	static class WebConfig {
@@ -137,6 +152,7 @@ public class WebSocketIntegrationTests extends AbstractWebSocketIntegrationTests
 			map.put("/echo", new EchoWebSocketHandler());
 			map.put("/sub-protocol", new SubProtocolWebSocketHandler());
 			map.put("/custom-header", new CustomHeaderHandler());
+			map.put("/close", new SessionClosingHandler());
 
 			SimpleUrlHandlerMapping mapping = new SimpleUrlHandlerMapping();
 			mapping.setUrlMap(map);
@@ -183,4 +199,12 @@ public class WebSocketIntegrationTests extends AbstractWebSocketIntegrationTests
 		}
 	}
 
+	private static class SessionClosingHandler implements WebSocketHandler {
+
+		@Override
+		public Mono<Void> handle(WebSocketSession session) {
+			return Flux.never().mergeWith(session.close(CloseStatus.GOING_AWAY)).then();
+		}
+	}
+
 }