Call onAllDataRead when read() returns -1

When read returns -1, we know we've reached the end of input. Instead
of waiting for the onAllDataRead container callback, this commit
proactively calls onAllDataRead.

Issue: SPR-16521

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

@@ -1,5 +1,5 @@
 /*
- * 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.
@@ -38,6 +38,7 @@ import reactor.core.publisher.Flux;
 
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferFactory;
+import org.springframework.core.io.buffer.DefaultDataBufferFactory;
 import org.springframework.http.HttpCookie;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
@@ -60,6 +61,8 @@ class ServletServerHttpRequest extends AbstractServerHttpRequest {
 
 	private static final String SSL_SESSION_ID_ATTRIBUTE = "javax.servlet.request.ssl_session_id";
 
+	static final DataBuffer EOF_BUFFER = new DefaultDataBufferFactory().allocateBuffer(0);
+
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
@@ -197,7 +200,7 @@ class ServletServerHttpRequest extends AbstractServerHttpRequest {
 	 * Invoked only when {@link ServletInputStream#isReady()} returns "true".
 	 */
 	@Nullable
-	protected DataBuffer readFromInputStream() throws IOException {
+	DataBuffer readFromInputStream() throws IOException {
 		int read = this.request.getInputStream().read(this.buffer);
 		if (logger.isTraceEnabled()) {
 			logger.trace("InputStream read returned " + read + (read != -1 ? " bytes" : ""));
@@ -208,6 +211,9 @@ class ServletServerHttpRequest extends AbstractServerHttpRequest {
 			dataBuffer.write(this.buffer, 0, read);
 			return dataBuffer;
 		}
+		else if (read == -1) {
+			return EOF_BUFFER;
+		}
 
 		return null;
 	}
@@ -266,7 +272,14 @@ class ServletServerHttpRequest extends AbstractServerHttpRequest {
 		@Nullable
 		protected DataBuffer read() throws IOException {
 			if (this.inputStream.isReady()) {
-				return readFromInputStream();
+				DataBuffer dataBuffer = readFromInputStream();
+				if (dataBuffer != EOF_BUFFER) {
+					return dataBuffer;
+				}
+				else {
+					// No need to wait for container callback...
+					onAllDataRead();
+				}
 			}
 			return null;
 		}

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

@@ -1,5 +1,5 @@
 /*
- * 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.
@@ -93,6 +93,9 @@ public class TomcatHttpHandlerAdapter extends ServletHttpHandlerAdapter {
 					release = false;
 					return dataBuffer;
 				}
+				else if (read == -1) {
+					return EOF_BUFFER;
+				}
 				else {
 					return null;
 				}