[wicket] branch wicket-8.x updated: WICKET-7041 Introduce `LazyStringResponse` to avoid unnecessary allocations for empty responses (#572)

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adelbene pushed a commit to branch wicket-8.x
in repository https://gitbox.apache.org/repos/asf/wicket.git


The following commit(s) were added to refs/heads/wicket-8.x by this push:
     new 71ae3b85d6 WICKET-7041 Introduce `LazyStringResponse` to avoid unnecessary allocations for empty responses (#572)
71ae3b85d6 is described below

commit 71ae3b85d6056dc67731de55942d08b9e86d8ddd
Author: Thomas Heigl <th...@gmail.com>
AuthorDate: Tue Apr 11 17:10:32 2023 +0200

    WICKET-7041 Introduce `LazyStringResponse` to avoid unnecessary allocations for empty responses (#572)
---
 .../src/main/java/org/apache/wicket/Component.java |   4 +-
 .../apache/wicket/response/LazyStringResponse.java | 116 +++++++++++++++++++++
 2 files changed, 118 insertions(+), 2 deletions(-)

diff --git a/wicket-core/src/main/java/org/apache/wicket/Component.java b/wicket-core/src/main/java/org/apache/wicket/Component.java
index c7dd922006..7097bb6bb9 100644
--- a/wicket-core/src/main/java/org/apache/wicket/Component.java
+++ b/wicket-core/src/main/java/org/apache/wicket/Component.java
@@ -77,7 +77,7 @@ import org.apache.wicket.request.component.IRequestablePage;
 import org.apache.wicket.request.cycle.RequestCycle;
 import org.apache.wicket.request.mapper.parameter.PageParameters;
 import org.apache.wicket.request.resource.ResourceReference;
-import org.apache.wicket.response.StringResponse;
+import org.apache.wicket.response.LazyStringResponse;
 import org.apache.wicket.settings.DebugSettings;
 import org.apache.wicket.settings.ExceptionSettings;
 import org.apache.wicket.util.IHierarchical;
@@ -2633,7 +2633,7 @@ public abstract class Component
 			// Allow component to contribute
 			if (response.wasRendered(this) == false)
 			{
-				StringResponse markupHeaderResponse = new StringResponse();
+				LazyStringResponse markupHeaderResponse = new LazyStringResponse();
 				Response oldResponse = getResponse();
 				RequestCycle.get().setResponse(markupHeaderResponse);
 				try
diff --git a/wicket-core/src/main/java/org/apache/wicket/response/LazyStringResponse.java b/wicket-core/src/main/java/org/apache/wicket/response/LazyStringResponse.java
new file mode 100644
index 0000000000..322e428383
--- /dev/null
+++ b/wicket-core/src/main/java/org/apache/wicket/response/LazyStringResponse.java
@@ -0,0 +1,116 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.wicket.response;
+
+import org.apache.wicket.request.Response;
+import org.apache.wicket.util.string.AppendingStringBuffer;
+
+
+/**
+ * Response object that writes to an AppendingStringBuffer. This class is functionally equivalent to
+ * {@link StringResponse}, but defers creating the buffer until it is needed.
+ * 
+ * @author Thomas Heigl
+ */
+public class LazyStringResponse extends Response
+{
+
+	private static final int DEFAULT_INITIAL_CAPACITY = 128;
+
+	/** Initial capacity of the buffer */
+	private final int initialCapacity;
+
+	/** Buffer to write to */
+	private AppendingStringBuffer out;
+
+	public LazyStringResponse()
+	{
+		this(DEFAULT_INITIAL_CAPACITY);
+	}
+
+	public LazyStringResponse(int initialCapacity)
+	{
+		this.initialCapacity = initialCapacity;
+	}
+
+	/**
+	 * @see Response#write(CharSequence)
+	 */
+	@Override
+	public void write(final CharSequence string)
+	{
+		if (out == null)
+		{
+			out = new AppendingStringBuffer(initialCapacity);
+		}
+		out.append(string);
+	}
+
+	/**
+	 * @see Response#reset()
+	 */
+	@Override
+	public void reset()
+	{
+		if (out != null)
+		{
+			out.clear();
+		}
+	}
+
+	/**
+	 * @see Object#toString()
+	 */
+	@Override
+	public String toString()
+	{
+		return getBuffer().toString();
+	}
+
+	/**
+	 * @return The internal buffer as a {@link CharSequence} or an empty string if no content has
+	 *         been written to the response
+	 */
+	public CharSequence getBuffer()
+	{
+		return out != null ? out : "";
+	}
+
+	@Override
+	public void write(byte[] array)
+	{
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public void write(byte[] array, int offset, int length)
+	{
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public String encodeURL(CharSequence url)
+	{
+		return url != null ? url.toString() : null;
+	}
+
+	@Override
+	public Object getContainerResponse()
+	{
+		return null;
+	}
+}