Merge branch '6.0.x'

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitter.java

@@ -128,9 +128,7 @@ public class ResponseBodyEmitter {
 		this.handler = handler;
 
 		try {
-			for (DataWithMediaType sendAttempt : this.earlySendAttempts) {
-				sendInternal(sendAttempt.getData(), sendAttempt.getMediaType());
-			}
+			sendInternal(this.earlySendAttempts);
 		}
 		finally {
 			this.earlySendAttempts.clear();
@@ -194,11 +192,7 @@ public class ResponseBodyEmitter {
 	 */
 	public synchronized void send(Object object, @Nullable MediaType mediaType) throws IOException {
 		Assert.state(!this.complete, () -> "ResponseBodyEmitter has already completed" +
-						(this.failure != null ? " with error: " + this.failure : ""));
-		sendInternal(object, mediaType);
-	}
-
-	private void sendInternal(Object object, @Nullable MediaType mediaType) throws IOException {
+				(this.failure != null ? " with error: " + this.failure : ""));
 		if (this.handler != null) {
 			try {
 				this.handler.send(object, mediaType);
@@ -217,6 +211,43 @@ public class ResponseBodyEmitter {
 		}
 	}
 
+	/**
+	 * Write a set of data and MediaType pairs in a batch.
+	 * <p>Compared to {@link #send(Object, MediaType)}, this batches the write operations
+	 * and flushes to the network at the end.
+	 * @param items the object and media type pairs to write
+	 * @throws IOException raised when an I/O error occurs
+	 * @throws java.lang.IllegalStateException wraps any other errors
+	 * @since 6.0.12
+	 */
+	public synchronized void send(Set<DataWithMediaType> items) throws IOException {
+		Assert.state(!this.complete, () -> "ResponseBodyEmitter has already completed" +
+				(this.failure != null ? " with error: " + this.failure : ""));
+		sendInternal(items);
+	}
+
+	private void sendInternal(Set<DataWithMediaType> items) throws IOException {
+		if (items.isEmpty()) {
+			return;
+		}
+		if (this.handler != null) {
+			try {
+				this.handler.send(items);
+			}
+			catch (IOException ex) {
+				this.sendFailed = true;
+				throw ex;
+			}
+			catch (Throwable ex) {
+				this.sendFailed = true;
+				throw new IllegalStateException("Failed to send " + items, ex);
+			}
+		}
+		else {
+			this.earlySendAttempts.addAll(items);
+		}
+	}
+
 	/**
 	 * Complete request processing by performing a dispatch into the servlet
 	 * container, where Spring MVC is invoked once more, and completes the
@@ -302,8 +333,17 @@ public class ResponseBodyEmitter {
 	 */
 	interface Handler {
 
+		/**
+		 * Immediately write and flush the given data to the network.
+		 */
 		void send(Object data, @Nullable MediaType mediaType) throws IOException;
 
+		/**
+		 * Immediately write all data items then flush to the network.
+		 * @since 6.0.12
+		 */
+		void send(Set<DataWithMediaType> items) throws IOException;
+
 		void complete();
 
 		void completeWithError(Throwable failure);

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterReturnValueHandler.java

@@ -20,6 +20,7 @@ import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Set;
 import java.util.function.Consumer;
 
 import jakarta.servlet.ServletRequest;
@@ -202,6 +203,15 @@ public class ResponseBodyEmitterReturnValueHandler implements HandlerMethodRetur
 		@Override
 		public void send(Object data, @Nullable MediaType mediaType) throws IOException {
 			sendInternal(data, mediaType);
+			this.outputMessage.flush();
+		}
+
+		@Override
+		public void send(Set<ResponseBodyEmitter.DataWithMediaType> items) throws IOException {
+			for (ResponseBodyEmitter.DataWithMediaType item : items) {
+				sendInternal(item.getData(), item.getMediaType());
+			}
+			this.outputMessage.flush();
 		}
 
 		@SuppressWarnings("unchecked")
@@ -209,7 +219,6 @@ public class ResponseBodyEmitterReturnValueHandler implements HandlerMethodRetur
 			for (HttpMessageConverter<?> converter : ResponseBodyEmitterReturnValueHandler.this.sseMessageConverters) {
 				if (converter.canWrite(data.getClass(), mediaType)) {
 					((HttpMessageConverter<T>) converter).write(data, mediaType, this.outputMessage);
-					this.outputMessage.flush();
 					return;
 				}
 			}

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/SseEmitter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -123,9 +123,7 @@ public class SseEmitter extends ResponseBodyEmitter {
 	public void send(SseEventBuilder builder) throws IOException {
 		Set<DataWithMediaType> dataToSend = builder.build();
 		synchronized (this) {
-			for (DataWithMediaType entry : dataToSend) {
-				super.send(entry.getData(), entry.getMediaType());
-			}
+			super.send(dataToSend);
 		}
 	}