Avoid temporary String object creation in StreamMessageProducer

org.eclipse.lsp4j.jsonrpc/src/main/java/org/eclipse/lsp4j/jsonrpc/json/StreamMessageProducer.java

@@ -1,19 +1,21 @@
 /******************************************************************************
  * Copyright (c) 2016 TypeFox and others.
- * 
+ *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0 which is available at
  * http://www.eclipse.org/legal/epl-2.0,
  * or the Eclipse Distribution License v. 1.0 which is available at
  * http://www.eclipse.org/org/documents/edl-v10.php.
- * 
+ *
  * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
  ******************************************************************************/
 package org.eclipse.lsp4j.jsonrpc.json;
 
 import java.io.Closeable;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.Reader;
 import java.nio.charset.StandardCharsets;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -24,6 +26,7 @@
 import org.eclipse.lsp4j.jsonrpc.MessageIssueHandler;
 import org.eclipse.lsp4j.jsonrpc.MessageProducer;
 import org.eclipse.lsp4j.jsonrpc.messages.Message;
+import org.eclipse.lsp4j.jsonrpc.util.LimitedInputStream;
 
 /**
  * A message producer that reads from an input stream and parses messages from JSON.
@@ -43,7 +46,7 @@ public class StreamMessageProducer implements MessageProducer, Closeable, Messag
 	public StreamMessageProducer(InputStream input, MessageJsonHandler jsonHandler) {
 		this(input, jsonHandler, null);
 	}
-	
+
 	public StreamMessageProducer(InputStream input, MessageJsonHandler jsonHandler, MessageIssueHandler issueHandler) {
 		this.input = input;
 		this.jsonHandler = jsonHandler;
@@ -133,7 +136,7 @@ protected void fireError(Throwable error) {
 		String message = error.getMessage() != null ? error.getMessage() : "An error occurred while processing an incoming message.";
 		LOG.log(Level.SEVERE, message, error);
 	}
-	
+
 	/**
 	 * Report that the stream was closed through an exception.
 	 */
@@ -169,27 +172,15 @@ protected void parseHeader(String line, Headers headers) {
 
 	/**
 	 * Read the JSON content part of a message, parse it, and notify the callback.
-	 * 
+	 *
 	 * @return {@code true} if we should continue reading from the input stream, {@code false} if we should stop
 	 */
 	protected boolean handleMessage(InputStream input, Headers headers) throws IOException {
 		if (callback == null)
 			callback = message -> LOG.log(Level.INFO, "Received message: " + message);
-
-		try {
-			int contentLength = headers.contentLength;
-			byte[] buffer = new byte[contentLength];
-			int bytesRead = 0;
-
-			while (bytesRead < contentLength) {
-				int readResult = input.read(buffer, bytesRead, contentLength - bytesRead);
-				if (readResult == -1)
-					return false;
-				bytesRead += readResult;
-			}
 
-			String content = new String(buffer, headers.charset);
-			try {
+		try {
+			try (final Reader content = new InputStreamReader(new LimitedInputStream(input, headers.contentLength, false), headers.charset)) {
 				Message message = jsonHandler.parseMessage(content);
 				callback.consume(message);
 			} catch (MessageIssueException exception) {

org.eclipse.lsp4j.jsonrpc/src/main/java/org/eclipse/lsp4j/jsonrpc/util/LimitedInputStream.java

@@ -0,0 +1,101 @@
+/******************************************************************************
+ * Copyright (c) 2024 Sebastian Thomschke and others.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0,
+ * or the Eclipse Distribution License v. 1.0 which is available at
+ * http://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
+ ******************************************************************************/
+package org.eclipse.lsp4j.jsonrpc.util;
+
+import java.io.FilterInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+public class LimitedInputStream extends FilterInputStream {
+	private static final int EOF = -1;
+
+	private int bytesRemaining;
+	private final boolean closeWrapped;
+	private boolean isClosed;
+	private int mark = EOF;
+
+	/**
+	 * @param closeWrapped controls if the underlying {@link InputStream} should also be closed via {@link #close()}
+	 */
+	public LimitedInputStream(final InputStream wrapped, final int maxBytesToRead, final boolean closeWrapped) {
+		super(wrapped);
+		if (maxBytesToRead < 0)
+			throw new IllegalArgumentException("[maxBytesToRead] must be >= 0");
+		bytesRemaining = maxBytesToRead;
+		this.closeWrapped = closeWrapped;
+	}
+
+	@Override
+	public int available() throws IOException {
+		if (isClosed)
+			return 0;
+		final int availableBytes = in.available();
+		return Math.min(availableBytes, bytesRemaining);
+	}
+
+	@Override
+	public void close() throws IOException {
+		if (closeWrapped) {
+			in.close();
+		}
+		isClosed = true;
+	}
+
+	@Override
+	public int read() throws IOException {
+		if (isClosed || bytesRemaining < 1)
+			return EOF;
+
+		final int data = in.read();
+		if (data != EOF) {
+			bytesRemaining--;
+		}
+		return data;
+	}
+
+	@Override
+	public int read(final byte[] b, final int off, final int len) throws IOException {
+		if (isClosed || bytesRemaining < 1)
+			return EOF;
+
+		final int bytesRead = in.read(b, off, Math.min(len, bytesRemaining));
+		if (bytesRead != EOF) {
+			bytesRemaining -= bytesRead;
+		}
+		return bytesRead;
+	}
+
+	@Override
+	public synchronized void mark(final int readlimit) {
+		in.mark(readlimit);
+		mark = bytesRemaining;
+	}
+
+	@Override
+	public synchronized void reset() throws IOException {
+		if (!in.markSupported())
+			throw new IOException("mark/reset not supported");
+
+		if (mark == EOF)
+			throw new IOException("mark not set");
+
+		in.reset();
+		bytesRemaining = mark;
+	}
+
+	@Override
+	public long skip(final long n) throws IOException {
+		final long skipped = in.skip(Math.min(n, bytesRemaining));
+		bytesRemaining -= skipped;
+		return skipped;
+	}
+}