From 0c9f7c2d3c79fa39839a9b4d93ee26afa9be6029 Mon Sep 17 00:00:00 2001
From: Santiago Pericas-Geertsen <santiago.pericasgeertsen@oracle.com>
Date: Wed, 2 Oct 2024 10:04:45 -0400
Subject: [PATCH] Allows the webserver's write buffer size to be set to 0 (or
 less). The underlying output stream shall not be wrapped into a buffered
 output stream one unless this value is greater than 0.

---
 .../tests/OutputStreamBufferSizeTest.java     | 35 +++++++++++++++++++
 .../webserver/tests/OutputStreamTest.java     |  4 +--
 .../webserver/http1/Http1ServerResponse.java  |  8 +++--
 3 files changed, 43 insertions(+), 4 deletions(-)
 create mode 100644 webserver/tests/webserver/src/test/java/io/helidon/webserver/tests/OutputStreamBufferSizeTest.java

diff --git a/webserver/tests/webserver/src/test/java/io/helidon/webserver/tests/OutputStreamBufferSizeTest.java b/webserver/tests/webserver/src/test/java/io/helidon/webserver/tests/OutputStreamBufferSizeTest.java
new file mode 100644
index 00000000000..966e1a54549
--- /dev/null
+++ b/webserver/tests/webserver/src/test/java/io/helidon/webserver/tests/OutputStreamBufferSizeTest.java
@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.helidon.webserver.tests;
+
+import io.helidon.webclient.http1.Http1Client;
+import io.helidon.webserver.WebServerConfig;
+import io.helidon.webserver.testing.junit5.ServerTest;
+import io.helidon.webserver.testing.junit5.SetUpServer;
+
+@ServerTest
+class OutputStreamBufferSizeTest extends OutputStreamTest {
+
+    OutputStreamBufferSizeTest(Http1Client client) {
+        super(client);
+    }
+
+    @SetUpServer
+    static void setup(WebServerConfig.Builder builder) {
+        builder.writeBufferSize(0);         // should accept buffer size of 0
+    }
+}
diff --git a/webserver/tests/webserver/src/test/java/io/helidon/webserver/tests/OutputStreamTest.java b/webserver/tests/webserver/src/test/java/io/helidon/webserver/tests/OutputStreamTest.java
index 2411e420644..3733604eda5 100644
--- a/webserver/tests/webserver/src/test/java/io/helidon/webserver/tests/OutputStreamTest.java
+++ b/webserver/tests/webserver/src/test/java/io/helidon/webserver/tests/OutputStreamTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, 2023 Oracle and/or its affiliates.
+ * Copyright (c) 2022, 2024 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -59,7 +59,7 @@ void verifyAutoFlush() {
         }
     }
 
-    private static class Service {
+    protected static class Service {
 
         public static void outputStream(ServerRequest req, ServerResponse res) throws IOException {
             InputStream in = new ByteArrayInputStream("Hello World".getBytes(StandardCharsets.UTF_8));
diff --git a/webserver/webserver/src/main/java/io/helidon/webserver/http1/Http1ServerResponse.java b/webserver/webserver/src/main/java/io/helidon/webserver/http1/Http1ServerResponse.java
index 330611ae76b..cd1194e2440 100644
--- a/webserver/webserver/src/main/java/io/helidon/webserver/http1/Http1ServerResponse.java
+++ b/webserver/webserver/src/main/java/io/helidon/webserver/http1/Http1ServerResponse.java
@@ -753,15 +753,19 @@ private void writeContent(BufferData buffer) throws IOException {
      * A special stream that provides buffering for a delegate and special handling
      * of close logic. Note that due to some locking issues in the JDK, this class
      * must use delegation with {@link BufferedOutputStream} instead of subclassing.
+     *
+     * <p>If the buffer size is less or equal to zero, it will not wrap the
+     * {@link io.helidon.webserver.http1.Http1ServerResponse.BlockingOutputStream}
+     * with a {@link java.io.BufferedOutputStream}.
      */
     static class ClosingBufferedOutputStream extends OutputStream {
 
         private final BlockingOutputStream delegate;
-        private final BufferedOutputStream bufferedDelegate;
+        private final OutputStream bufferedDelegate;
 
         ClosingBufferedOutputStream(BlockingOutputStream out, int size) {
             this.delegate = out;
-            this.bufferedDelegate = new BufferedOutputStream(out, size);
+            this.bufferedDelegate = size <= 0 ? out : new BufferedOutputStream(out, size);
         }
 
         @Override