Rename InputStreamSubscriber to SubscriberInputStream

It is both, but InputStream is what's exposed for public use,
in effect an InputStream backed by a Subscriber source.

See gh-31677

Author: rstoyanchev

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

@@ -472,16 +472,16 @@ public static Publisher<DataBuffer> outputStreamPublisher(
 	 * Note: {@link Subscription#request(long)} happens eagerly for the first time upon subscription
 	 * and then repeats every time {@code bufferSize - (bufferSize >> 2)} consumed.
 	 * @param publisher the source of {@link DataBuffer} which should be represented as an {@link InputStream}
-	 * @param bufferSize the maximum amount of {@link DataBuffer} prefetched in advance and stored inside {@link InputStream}
+	 * @param demand the maximum number of buffers to request from the Publisher and buffer on an ongoing basis
 	 * @return an {@link InputStream} instance representing given {@link Publisher} messages
 	 */
-	public static <T extends DataBuffer> InputStream subscribeAsInputStream(Publisher<T> publisher, int bufferSize) {
+	public static <T extends DataBuffer> InputStream subscriberInputStream(Publisher<T> publisher, int demand) {
 		Assert.notNull(publisher, "Publisher must not be null");
-		Assert.isTrue(bufferSize > 0, "Buffer size must be > 0");
+		Assert.isTrue(demand > 0, "maxBufferCount must be > 0");
 
-		InputStreamSubscriber inputStreamSubscriber = new InputStreamSubscriber(bufferSize);
-		publisher.subscribe(inputStreamSubscriber);
-		return inputStreamSubscriber;
+		SubscriberInputStream subscriber = new SubscriberInputStream(demand);
+		publisher.subscribe(subscriber);
+		return subscriber;
 	}
 
 

spring-core/src/main/java/org/springframework/core/io/buffer/InputStreamSubscriber.java renamed to spring-core/src/main/java/org/springframework/core/io/buffer/SubscriberInputStream.java

@@ -39,13 +39,13 @@
  * Bridges between {@link Publisher Publisher<DataBuffer>} and {@link InputStream}.
  *
  * <p>Note that this class has a near duplicate in
- * {@link org.springframework.http.client.InputStreamSubscriber}.
+ * {@link org.springframework.http.client.SubscriberInputStream}.
  *
  * @author Oleh Dokuka
  * @author Rossen Stoyanchev
  * @since 6.2
  */
-final class InputStreamSubscriber extends InputStream implements Subscriber<DataBuffer> {
+final class SubscriberInputStream extends InputStream implements Subscriber<DataBuffer> {
 
 	private static final Object READY = new Object();
 
@@ -82,10 +82,10 @@ final class InputStreamSubscriber extends InputStream implements Subscriber<Data
 	private Throwable error;
 
 
-	InputStreamSubscriber(int prefetch) {
-		this.prefetch = prefetch;
-		this.limit = (prefetch == Integer.MAX_VALUE ? Integer.MAX_VALUE : prefetch - (prefetch >> 2));
-		this.queue = new ArrayBlockingQueue<>(prefetch);
+	SubscriberInputStream(int demand) {
+		this.prefetch = demand;
+		this.limit = (demand == Integer.MAX_VALUE ? Integer.MAX_VALUE : demand - (demand >> 2));
+		this.queue = new ArrayBlockingQueue<>(demand);
 		this.lock = new ReentrantLock(false);
 	}
 

spring-core/src/test/java/org/springframework/core/io/buffer/DataBufferUtilsTests.java

@@ -754,7 +754,7 @@ void genericInputStreamSubscriberTest(
 		byte[] chunk = new byte[readChunkSize];
 		List<String> words = new ArrayList<>();
 
-		try (InputStream in = DataBufferUtils.subscribeAsInputStream(publisher, bufferSize)) {
+		try (InputStream in = DataBufferUtils.subscriberInputStream(publisher, bufferSize)) {
 			int read;
 			while ((read = in.read(chunk)) > -1) {
 				words.add(new String(chunk, 0, read, StandardCharsets.UTF_8));
@@ -791,7 +791,7 @@ void inputStreamSubscriberError(DataBufferFactory factory) {
 		byte[] chunk = new byte[4];
 		List<String> words = new ArrayList<>();
 
-		try (InputStream in = DataBufferUtils.subscribeAsInputStream(publisher, 1)) {
+		try (InputStream in = DataBufferUtils.subscriberInputStream(publisher, 1)) {
 			int read;
 			while ((read = in.read(chunk)) > -1) {
 				words.add(new String(chunk, 0, read, StandardCharsets.UTF_8));
@@ -830,7 +830,7 @@ void inputStreamSubscriberMixedReadMode(DataBufferFactory factory) {
 		byte[] chunk = new byte[3];
 		ArrayList<String> words = new ArrayList<>();
 
-		try (InputStream inputStream = DataBufferUtils.subscribeAsInputStream(publisher, 1)) {
+		try (InputStream inputStream = DataBufferUtils.subscriberInputStream(publisher, 1)) {
 			words.add(new String(chunk,0, inputStream.read(chunk), StandardCharsets.UTF_8));
 			assertThat(inputStream.read()).isEqualTo(' ' & 0xFF);
 			words.add(new String(chunk,0, inputStream.read(chunk), StandardCharsets.UTF_8));
@@ -874,7 +874,7 @@ void inputStreamSubscriberClose(DataBufferFactory bufferFactory) throws Interrup
 			byte[] chunk = new byte[3];
 			ArrayList<String> words = new ArrayList<>();
 
-			try (InputStream in = DataBufferUtils.subscribeAsInputStream(publisher, ThreadLocalRandom.current().nextInt(1, 4))) {
+			try (InputStream in = DataBufferUtils.subscriberInputStream(publisher, ThreadLocalRandom.current().nextInt(1, 4))) {
 				in.read(chunk);
 				String word = new String(chunk, StandardCharsets.UTF_8);
 				words.add(word);

spring-web/src/main/java/org/springframework/http/client/InputStreamSubscriber.java renamed to spring-web/src/main/java/org/springframework/http/client/SubscriberInputStream.java

@@ -42,16 +42,16 @@
  * Bridges between {@link Flow.Publisher Flow.Publisher<T>} and {@link InputStream}.
  *
  * <p>Note that this class has a near duplicate in
- * {@link org.springframework.core.io.buffer.InputStreamSubscriber}.
+ * {@link org.springframework.core.io.buffer.SubscriberInputStream}.
  *
  * @author Oleh Dokuka
  * @author Rossen Stoyanchev
  * @since 6.2
  * @param <T> the publisher byte buffer type
  */
-final class InputStreamSubscriber<T> extends InputStream implements Flow.Subscriber<T> {
+final class SubscriberInputStream<T> extends InputStream implements Flow.Subscriber<T> {
 
-	private static final Log logger = LogFactory.getLog(InputStreamSubscriber.class);
+	private static final Log logger = LogFactory.getLog(SubscriberInputStream.class);
 
 	private static final Object READY = new Object();
 
@@ -94,12 +94,12 @@ final class InputStreamSubscriber<T> extends InputStream implements Flow.Subscri
 	private Throwable error;
 
 
-	private InputStreamSubscriber(Function<T, byte[]> mapper, Consumer<T> onDiscardHandler, int prefetch) {
+	private SubscriberInputStream(Function<T, byte[]> mapper, Consumer<T> onDiscardHandler, int demand) {
 		this.mapper = mapper;
 		this.onDiscardHandler = onDiscardHandler;
-		this.prefetch = prefetch;
-		this.limit = (prefetch == Integer.MAX_VALUE ? Integer.MAX_VALUE : prefetch - (prefetch >> 2));
-		this.queue = new ArrayBlockingQueue<>(prefetch);
+		this.prefetch = demand;
+		this.limit = (demand == Integer.MAX_VALUE ? Integer.MAX_VALUE : demand - (demand >> 2));
+		this.queue = new ArrayBlockingQueue<>(demand);
 		this.lock = new ReentrantLock(false);
 	}
 
@@ -122,17 +122,16 @@ private InputStreamSubscriber(Function<T, byte[]> mapper, Consumer<T> onDiscardH
 	 * @param publisher the source of {@link DataBuffer} which should be represented as an {@link InputStream}
 	 * @param mapper function to transform &lt;T&gt; element to {@code byte[]}. Note, &lt;T&gt; should be released during the mapping if needed.
 	 * @param onDiscardHandler &lt;T&gt; element consumer if returned {@link InputStream} is closed prematurely.
-	 * @param bufferSize the maximum amount of &lt;T&gt; elements prefetched in advance and stored inside {@link InputStream}
+	 * @param demand the maximum number of buffers to request from the Publisher and buffer on an ongoing basis
 	 * @return an {@link InputStream} instance representing given {@link Flow.Publisher} messages
 	 */
-	public static <T> InputStream subscribeTo(Flow.Publisher<T> publisher, Function<T, byte[]> mapper, Consumer<T> onDiscardHandler, int bufferSize) {
-
+	public static <T> InputStream subscribeTo(Flow.Publisher<T> publisher, Function<T, byte[]> mapper, Consumer<T> onDiscardHandler, int demand) {
 		Assert.notNull(publisher, "Flow.Publisher must not be null");
 		Assert.notNull(mapper, "mapper must not be null");
 		Assert.notNull(onDiscardHandler, "onDiscardHandler must not be null");
-		Assert.isTrue(bufferSize > 0, "bufferSize must be greater than 0");
+		Assert.isTrue(demand > 0, "demand must be greater than 0");
 
-		InputStreamSubscriber<T> iss = new InputStreamSubscriber<>(mapper, onDiscardHandler, bufferSize);
+		SubscriberInputStream<T> iss = new SubscriberInputStream<>(mapper, onDiscardHandler, demand);
 		publisher.subscribe(iss);
 		return iss;
 	}

spring-web/src/test/java/org/springframework/http/client/InputStreamSubscriberTests.java renamed to spring-web/src/test/java/org/springframework/http/client/SubscriberInputStreamTests.java

@@ -36,12 +36,12 @@
 import static org.assertj.core.api.Assertions.assertThatIOException;
 
 /**
- * Unit tests for {@link InputStreamSubscriber}.
+ * Unit tests for {@link SubscriberInputStream}.
  *
  * @author Arjen Poutsma
  * @author Oleh Dokuka
  */
-class InputStreamSubscriberTests {
+class SubscriberInputStreamTests {
 
 	private static final byte[] FOO = "foo".getBytes(UTF_8);
 
@@ -98,7 +98,7 @@ void flush() throws IOException {
 				this.byteMapper, this.executor, null);
 
 
-		try (InputStream is = InputStreamSubscriber.subscribeTo(
+		try (InputStream is = SubscriberInputStream.subscribeTo(
 				toStringPublisher(publisher), s -> s.getBytes(UTF_8), s -> {}, 1)) {
 
 			byte[] chunk = new byte[3];
@@ -123,7 +123,7 @@ void chunkSize() {
 				},
 				this.byteMapper, this.executor, 2);
 
-		try (InputStream is = InputStreamSubscriber.subscribeTo(
+		try (InputStream is = SubscriberInputStream.subscribeTo(
 				toStringPublisher(publisher), s -> s.getBytes(UTF_8), s -> {}, 1)) {
 
 			StringBuilder stringBuilder = new StringBuilder();
@@ -167,7 +167,7 @@ void cancel() throws InterruptedException {
 
 		List<String> discarded = new ArrayList<>();
 
-		try (InputStream is = InputStreamSubscriber.subscribeTo(
+		try (InputStream is = SubscriberInputStream.subscribeTo(
 				toStringPublisher(publisher), s -> s.getBytes(UTF_8), discarded::add, 1)) {
 
 			byte[] chunk = new byte[3];
@@ -198,7 +198,7 @@ void closed() throws InterruptedException {
 				},
 				this.byteMapper, this.executor, null);
 
-		try (InputStream is = InputStreamSubscriber.subscribeTo(
+		try (InputStream is = SubscriberInputStream.subscribeTo(
 				toStringPublisher(publisher), s -> s.getBytes(UTF_8), s -> {}, 1)) {
 
 			byte[] chunk = new byte[3];
@@ -234,7 +234,7 @@ void mapperThrowsException() throws InterruptedException {
 		Throwable savedEx = null;
 
 		StringBuilder sb = new StringBuilder();
-		try (InputStream is = InputStreamSubscriber.subscribeTo(
+		try (InputStream is = SubscriberInputStream.subscribeTo(
 				publisher, s -> { throw new NullPointerException("boom"); }, s -> {}, 1)) {
 
 			byte[] chunk = new byte[3];