Renamed DataBufferUtils/DataBufferFactory.compose to join

Issue: SPR-16365

spring-core/src/main/java/org/springframework/core/codec/AbstractDataBufferDecoder.java

@@ -63,7 +63,7 @@ public abstract class AbstractDataBufferDecoder<T> extends AbstractDecoder<T> {
 	public Mono<T> decodeToMono(Publisher<DataBuffer> inputStream, ResolvableType elementType,
 			@Nullable MimeType mimeType, @Nullable Map<String, Object> hints) {
 
-		return DataBufferUtils.compose(inputStream)
+		return DataBufferUtils.join(inputStream)
 				.map(buffer -> decodeDataBuffer(buffer, elementType, mimeType, hints));
 	}
 

spring-core/src/main/java/org/springframework/core/io/buffer/DataBufferFactory.java

@@ -63,13 +63,15 @@ public interface DataBufferFactory {
 	DataBuffer wrap(byte[] bytes);
 
 	/**
-	 * Create a composite data buffer from the list of provided data buffers. Depending on the
-	 * implementation, the returned buffer may be a single buffer containing all data of the
-	 * provided buffers, or it may be a true composite that contains references to the buffers.
+	 * Return a new {@code DataBuffer} composed of the {@code dataBuffers} elements joined together.
+	 * Depending on the implementation, the returned buffer may be a single buffer containing all
+	 * data of the provided buffers, or it may be a true composite that contains references to the
+	 * buffers.
 	 * <p>Note that the given data buffers do <strong>not</strong> have to be released, as they are
 	 * released as part of the returned composite.
 	 * @param dataBuffers the data buffers to be composed
-	 * @return a buffer that composes {@code dataBuffers} into one
+	 * @return a buffer that is composed from the {@code dataBuffers} argument
+	 * @since 5.0.3
 	 */
-	DataBuffer compose(List<DataBuffer> dataBuffers);
+	DataBuffer join(List<? extends DataBuffer> dataBuffers);
 }

spring-core/src/main/java/org/springframework/core/io/buffer/DataBufferUtils.java

@@ -507,23 +507,23 @@ public abstract class DataBufferUtils {
 	}
 
 	/**
-	 * Composes the buffers in the given {@link Publisher} into a single data buffer. Depending on
-	 * the {@code DataBuffer} implementation, the returned buffer may be a single buffer containing
-	 * all data of the provided buffers, or it may be a true composite that contains references to
-	 * the buffers.
-	 * @param publisher the data buffers that are to be composed
-	 * @return the composed data buffer
+	 * Return a new {@code DataBuffer} composed of the {@code dataBuffers} elements joined together.
+	 * Depending on the {@link DataBuffer} implementation, the returned buffer may be a single
+	 * buffer containing all data of the provided buffers, or it may be a true composite that
+	 * contains references to the buffers.
+	 * @param dataBuffers the data buffers that are to be composed
+	 * @return a buffer that is composed from the {@code dataBuffers} argument
+	 * @since 5.0.3
 	 */
-	public static Mono<DataBuffer> compose(Publisher<DataBuffer> publisher) {
-		Assert.notNull(publisher, "'publisher' must not be null");
+	public static Mono<DataBuffer> join(Publisher<? extends DataBuffer> dataBuffers) {
+		Assert.notNull(dataBuffers, "'dataBuffers' must not be null");
 
-		Flux<DataBuffer> source = Flux.from(publisher);
-
-		return source.collectList()
-				.filter(dataBuffers -> !dataBuffers.isEmpty())
-				.map(dataBuffers -> {
-					DataBufferFactory bufferFactory = dataBuffers.get(0).factory();
-					return bufferFactory.compose(dataBuffers);
+		return Flux.from(dataBuffers)
+				.collectList()
+				.filter(list -> !list.isEmpty())
+				.map(list -> {
+					DataBufferFactory bufferFactory = list.get(0).factory();
+					return bufferFactory.join(list);
 				});
 	}
 

spring-core/src/main/java/org/springframework/core/io/buffer/DefaultDataBufferFactory.java

@@ -109,15 +109,18 @@ public class DefaultDataBufferFactory implements DataBufferFactory {
 	 * in {@code dataBuffers}.
 	 */
 	@Override
-	public DataBuffer compose(List<DataBuffer> dataBuffers) {
+	public DataBuffer join(List<? extends DataBuffer> dataBuffers) {
 		Assert.notEmpty(dataBuffers, "'dataBuffers' must not be empty");
 
 		int capacity = dataBuffers.stream()
 				.mapToInt(DataBuffer::readableByteCount)
 				.sum();
 		DefaultDataBuffer dataBuffer = allocateBuffer(capacity);
-		return dataBuffers.stream()
+		DataBuffer result = dataBuffers.stream()
+				.map(o -> (DataBuffer) o)
 				.reduce(dataBuffer, DataBuffer::write);
+		dataBuffers.forEach(DataBufferUtils::release);
+		return result;
 	}
 
 	@Override

spring-core/src/main/java/org/springframework/core/io/buffer/NettyDataBufferFactory.java

@@ -87,7 +87,7 @@ public class NettyDataBufferFactory implements DataBufferFactory {
 	 * <p>This implementation uses Netty's {@link CompositeByteBuf}.
 	 */
 	@Override
-	public DataBuffer compose(List<DataBuffer> dataBuffers) {
+	public DataBuffer join(List<? extends DataBuffer> dataBuffers) {
 		Assert.notNull(dataBuffers, "'dataBuffers' must not be null");
 		CompositeByteBuf composite = this.byteBufAllocator.compositeBuffer(dataBuffers.size());
 		for (DataBuffer dataBuffer : dataBuffers) {