From e2baf7277bdfa8b4a4da34fb0f0853413bec1a8f Mon Sep 17 00:00:00 2001
From: Rossen Stoyanchev <rstoyanchev@pivotal.io>
Date: Mon, 23 Sep 2019 13:32:28 +0100
Subject: [PATCH] Use metadata slice

Take a slice of the metadata if not using composite metadata to allow
reading it multiple times. For composite metadata this is not an isuse
as it is ensured by the underlying RSocket Java API.
---
 .../rsocket/DefaultMetadataExtractor.java     |  2 +-
 .../DefaultMetadataExtractorTests.java        | 44 +++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/spring-messaging/src/main/java/org/springframework/messaging/rsocket/DefaultMetadataExtractor.java b/spring-messaging/src/main/java/org/springframework/messaging/rsocket/DefaultMetadataExtractor.java
index b36a6fd83ea..1ce015f1814 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/rsocket/DefaultMetadataExtractor.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/rsocket/DefaultMetadataExtractor.java
@@ -116,7 +116,7 @@ public class DefaultMetadataExtractor implements MetadataExtractor, MetadataExtr
 			}
 		}
 		else {
-			extractEntry(payload.metadata(), metadataMimeType.toString(), result);
+			extractEntry(payload.metadata().slice(), metadataMimeType.toString(), result);
 		}
 		return result;
 	}
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultMetadataExtractorTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultMetadataExtractorTests.java
index cd1052a4ae6..c12a15160df 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultMetadataExtractorTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultMetadataExtractorTests.java
@@ -15,6 +15,7 @@
  */
 package org.springframework.messaging.rsocket;
 
+import java.nio.charset.StandardCharsets;
 import java.time.Duration;
 import java.util.Collections;
 import java.util.Map;
@@ -26,10 +27,14 @@ import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
+import org.springframework.core.ResolvableType;
+import org.springframework.core.codec.AbstractDataBufferDecoder;
 import org.springframework.core.codec.ByteArrayDecoder;
 import org.springframework.core.codec.StringDecoder;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferFactory;
+import org.springframework.core.io.buffer.DataBufferUtils;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.MimeType;
 import org.springframework.util.MimeTypeUtils;
@@ -156,6 +161,24 @@ public class DefaultMetadataExtractorTests {
 				.containsEntry("entry1", "text data");
 	}
 
+	@Test
+	public void nonCompositeMetadataCanBeReadTwice() {
+		DefaultMetadataExtractor extractor = new DefaultMetadataExtractor(new TestDecoder());
+		extractor.metadataToExtract(TEXT_PLAIN, String.class, "name");
+
+		MetadataEncoder encoder = new MetadataEncoder(TEXT_PLAIN, this.strategies).metadata("value", null);
+		DataBuffer metadata = encoder.encode();
+		Payload payload = createPayload(metadata);
+
+		Map<String, Object> result = extractor.extract(payload, TEXT_PLAIN);
+		assertThat(result).hasSize(1).containsEntry("name", "value");
+
+		result = extractor.extract(payload, TEXT_PLAIN);
+		assertThat(result).hasSize(1).containsEntry("name", "value");
+
+		payload.release();
+	}
+
 	@Test
 	public void noDecoder() {
 		DefaultMetadataExtractor extractor =
@@ -172,4 +195,25 @@ public class DefaultMetadataExtractorTests {
 		return PayloadUtils.createPayload(this.strategies.dataBufferFactory().allocateBuffer(), metadata);
 	}
 
+
+	/**
+	 * Like StringDecoder but consumes the reader index in order to prove that
+	 * extraction uses a slice and can be read twice.
+	 */
+	private static class TestDecoder extends AbstractDataBufferDecoder<String> {
+
+		public TestDecoder() {
+			super(TEXT_PLAIN);
+		}
+
+		@Override
+		public String decode(DataBuffer dataBuffer, ResolvableType elementType,
+				@Nullable MimeType mimeType, @Nullable Map<String, Object> hints) {
+
+			byte[] bytes = new byte[dataBuffer.readableByteCount()];
+			dataBuffer.read(bytes);
+			DataBufferUtils.release(dataBuffer);
+			return new String(bytes, StandardCharsets.UTF_8);
+		}
+	}
 }