[engine] optimization: use an unsynchronized string writer whenever possible

git-svn-id: https://svn.apache.org/repos/asf/velocity/engine/trunk@1773994 13f79535-47bb-0310-9956-ffa450edef68

4 files changed, 175 insertions, 6 deletions

diff --git a/velocity-engine-core/src/main/java/org/apache/velocity/runtime/directive/Block.java b/velocity-engine-core/src/main/java/org/apache/velocity/runtime/directive/Block.java
index 3f84fa48..5fccdaae 100755
--- a/velocity-engine-core/src/main/java/org/apache/velocity/runtime/directive/Block.java
+++ b/velocity-engine-core/src/main/java/org/apache/velocity/runtime/directive/Block.java
@@ -24,11 +24,11 @@ import org.apache.velocity.exception.TemplateInitException;
 import org.apache.velocity.runtime.Renderable;
 import org.apache.velocity.runtime.RuntimeServices;
 import org.apache.velocity.runtime.parser.node.Node;
+import org.apache.velocity.util.StringBuilderWriter;
 import org.apache.velocity.util.StringUtils;
 import org.slf4j.Logger;
 
 import java.io.IOException;
-import java.io.StringWriter;
 import java.io.Writer;
 
 /**
@@ -172,7 +172,7 @@ public abstract class Block extends Directive
 
         public String toString()
         {
-            Writer writer = new StringWriter();
+            Writer writer = new StringBuilderWriter();
             if (render(context, writer))
             {
                 return writer.toString();
diff --git a/velocity-engine-core/src/main/java/org/apache/velocity/runtime/parser/node/ASTStringLiteral.java b/velocity-engine-core/src/main/java/org/apache/velocity/runtime/parser/node/ASTStringLiteral.java
index 33e708e2..51179ee0 100644
--- a/velocity-engine-core/src/main/java/org/apache/velocity/runtime/parser/node/ASTStringLiteral.java
+++ b/velocity-engine-core/src/main/java/org/apache/velocity/runtime/parser/node/ASTStringLiteral.java
@@ -25,11 +25,12 @@ import org.apache.velocity.runtime.RuntimeConstants;
 import org.apache.velocity.runtime.parser.ParseException;
 import org.apache.velocity.runtime.parser.Parser;
 import org.apache.velocity.runtime.parser.Token;
+import org.apache.velocity.util.StringBuilderWriter;
 import org.apache.velocity.util.StringUtils;
 
 import java.io.IOException;
 import java.io.StringReader;
-import java.io.StringWriter;
+import java.io.Writer;
 
 /**
  * ASTStringLiteral support. Will interpolate!
@@ -306,7 +307,7 @@ public class ASTStringLiteral extends SimpleNode
                  * now render against the real context
                  */
 
-                StringWriter writer = new StringWriter();
+                Writer writer = new StringBuilderWriter();
                 nodeTree.render(context, writer);
 
                 /*
diff --git a/velocity-engine-core/src/main/java/org/apache/velocity/runtime/resource/ContentResource.java b/velocity-engine-core/src/main/java/org/apache/velocity/runtime/resource/ContentResource.java
index 7976fb4f..00b08c13 100644
--- a/velocity-engine-core/src/main/java/org/apache/velocity/runtime/resource/ContentResource.java
+++ b/velocity-engine-core/src/main/java/org/apache/velocity/runtime/resource/ContentResource.java
@@ -21,9 +21,10 @@ package org.apache.velocity.runtime.resource;
 
 import org.apache.velocity.exception.ResourceNotFoundException;
 import org.apache.velocity.exception.VelocityException;
+import org.apache.velocity.util.StringBuilderWriter;
 
 import java.io.BufferedReader;
-import java.io.StringWriter;
+import java.io.Writer;
 
 /**
  * This class represent a general text resource that may have been
@@ -60,7 +61,7 @@ public class ContentResource extends Resource
 
         try
         {
-            StringWriter sw = new StringWriter();
+            Writer sw = new StringBuilderWriter();
 
             reader = new BufferedReader(resourceLoader.getResourceReader(name, encoding));
 
diff --git a/velocity-engine-core/src/main/java/org/apache/velocity/util/StringBuilderWriter.java b/velocity-engine-core/src/main/java/org/apache/velocity/util/StringBuilderWriter.java
new file mode 100644
index 00000000..8a43649b
--- /dev/null
+++ b/velocity-engine-core/src/main/java/org/apache/velocity/util/StringBuilderWriter.java
@@ -0,0 +1,167 @@
+/*
+ * 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.velocity.util;
+
+import java.io.Serializable;
+import java.io.Writer;
+
+/**
+ * {@link Writer} implementation that outputs to a {@link StringBuilder}.
+ * <p>
+ * <strong>NOTE:</strong> This implementation, as an alternative to
+ * <code>java.io.StringWriter</code>, provides an <i>un-synchronized</i>
+ * (i.e. for use in a single thread) implementation for better performance.
+ * For safe usage with multiple {@link Thread}s then
+ * <code>java.io.StringWriter</code> should be used.</p>
+ *
+ * <p>(borrowed from commons.io project)</p>
+ *
+ * @version $Id$
+ * @since 2.0
+ */
+public class StringBuilderWriter extends Writer implements Serializable {
+
+    private static final long serialVersionUID = -146927496096066153L;
+    private final StringBuilder builder;
+
+    /**
+     * Constructs a new {@link StringBuilder} instance with default capacity.
+     */
+    public StringBuilderWriter() {
+        this.builder = new StringBuilder();
+    }
+
+    /**
+     * Constructs a new {@link StringBuilder} instance with the specified capacity.
+     *
+     * @param capacity The initial capacity of the underlying {@link StringBuilder}
+     */
+    public StringBuilderWriter(final int capacity) {
+        this.builder = new StringBuilder(capacity);
+    }
+
+    /**
+     * Constructs a new instance with the specified {@link StringBuilder}.
+     * 
+     * <p>If {@code builder} is null a new instance with default capacity will be created.</p>
+     *
+     * @param builder The String builder. May be null.
+     */
+    public StringBuilderWriter(final StringBuilder builder) {
+        this.builder = builder != null ? builder : new StringBuilder();
+    }
+
+    /**
+     * Appends a single character to this Writer.
+     *
+     * @param value The character to append
+     * @return This writer instance
+     */
+    @Override
+    public Writer append(final char value) {
+        builder.append(value);
+        return this;
+    }
+
+    /**
+     * Appends a character sequence to this Writer.
+     *
+     * @param value The character to append
+     * @return This writer instance
+     */
+    @Override
+    public Writer append(final CharSequence value) {
+        builder.append(value);
+        return this;
+    }
+
+    /**
+     * Appends a portion of a character sequence to the {@link StringBuilder}.
+     *
+     * @param value The character to append
+     * @param start The index of the first character
+     * @param end The index of the last character + 1
+     * @return This writer instance
+     */
+    @Override
+    public Writer append(final CharSequence value, final int start, final int end) {
+        builder.append(value, start, end);
+        return this;
+    }
+
+    /**
+     * Closing this writer has no effect. 
+     */
+    @Override
+    public void close() {
+        // no-op
+    }
+
+    /**
+     * Flushing this writer has no effect. 
+     */
+    @Override
+    public void flush() {
+        // no-op
+    }
+
+
+    /**
+     * Writes a String to the {@link StringBuilder}.
+     * 
+     * @param value The value to write
+     */
+    @Override
+    public void write(final String value) {
+        if (value != null) {
+            builder.append(value);
+        }
+    }
+
+    /**
+     * Writes a portion of a character array to the {@link StringBuilder}.
+     *
+     * @param value The value to write
+     * @param offset The index of the first character
+     * @param length The number of characters to write
+     */
+    @Override
+    public void write(final char[] value, final int offset, final int length) {
+        if (value != null) {
+            builder.append(value, offset, length);
+        }
+    }
+
+    /**
+     * Returns the underlying builder.
+     *
+     * @return The underlying builder
+     */
+    public StringBuilder getBuilder() {
+        return builder;
+    }
+
+    /**
+     * Returns {@link StringBuilder#toString()}.
+     *
+     * @return The contents of the String builder.
+     */
+    @Override
+    public String toString() {
+        return builder.toString();
+    }
+}