Hi All, Ahmed's comments the other day got me thinking about performance issues. One change we made to the Click Framework was to introduce a HtmlStringBuffer class, which is basically a traditional StringBuffer class but without the synchronization. This removes the need for synchronization checks, this provided a measurable performance improvement.
I did a quick search on Velocities code base and there are about 29 classes which have references to the class, some of them many be significant in terms of performance. Are their any performance related Velocity test cases, which could be used to evaluate a change? Are there threading issues with the Velocity engine which such a change could affect? regards Malcolm Edgar
/* * Copyright 2004-2005 Malcolm A. Edgar * * 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 net.sf.click.util; import java.util.Iterator; import java.util.Map; /** * Provides a HTML element StringBuffer for rendering, automatically * escaping string values. HtmlStringBuffer is used by Click controls * for HTML rendering. * <p/> * For example the following code: * <pre class="codeJava"> * <span class="kw">public</span> String toString() { * HtmlStringBuffer buffer = <span class="kw">new</span> HtmlStringBuffer(); * * buffer.elementStart(<span class="st">"input"</span>); * buffer.appendAttribute(<span class="st">"type"</span>, <span class="st">"text"</span>); * buffer.appendAttribute(<span class="st">"name"</span>, getName()); * buffer.appendAttribute(<span class="st">"value"</span>, getValue()); * buffer.elementEnd(); * * <span class="kw">return</span> buffer.toString(); * } </pre> * * Would render: * * <pre class="codeHtml"> * <input type="text" name="address" value="23 Holt's Street"/> </pre> * * <h4>Synchronization</h4> * * To improve performance in Click's thread safe environment this * class does not synchronize append operations. Internally this class uses * a character buffer adapted from the JDK 1.5 <tt>AbstractStringBuilder</tt>. * * @author Malcolm Edgar */ public class HtmlStringBuffer { // -------------------------------------------------------------- Constants /** JavaScript attribute names. */ static final String[] JS_ATTRIBUTES = { "onload", "onunload", "onclick", "ondblclick", "onmousedown", "onmouseup", "onmouseover", "onmousemove", "onmouseout", "onfocus", "onblur", "onkeypress", "onkeydown", "onkeyup", "onsubmit", "onreset", "onselect", "onchange" }; // ----------------------------------------------------- Instance Variables /** The character storage array. */ protected char[] characters; /** The count is the number of characters used. */ protected int count; // ----------------------------------------------------------- Constructors /** * Create a new HTML StringBuffer with the specified initial * capacity. * * @param length the initial capacity */ public HtmlStringBuffer(int length) { characters = new char[length]; } /** * Create a new HTML StringBuffer with an initial capacity of 128 * characters. */ public HtmlStringBuffer() { characters = new char[128]; } // --------------------------------------------------------- Public Methods /** * Append the char value to the buffer. * * @param value the char value to append */ public void append(char value) { int newcount = count + 1; if (newcount > characters.length) { expandCapacity(newcount); } characters[count++] = value; } /** * Append the integer value to the buffer. * * @param value the integer value to append */ public void append(int value) { append(String.valueOf(value)); } /** * Append the long value to the buffer. * * @param value the long value to append */ public void append(long value) { append(String.valueOf(value)); } /** * Append the raw object value of the given object to the buffer. * * @param value the object value to append */ public void append(Object value) { String string = String.valueOf(value); int length = string.length(); int newCount = count + length; if (newCount > characters.length) { expandCapacity(newCount); } string.getChars(0, length, characters, count); count = newCount; } /** * Append the raw string value of the given object to the buffer. * * @param value the string value to append */ public void append(String value) { String string = (value != null) ? value : "null"; int length = string.length(); int newCount = count + length; if (newCount > characters.length) { expandCapacity(newCount); } string.getChars(0, length, characters, count); count = newCount; } /** * Append the given value to the buffer and escape its HMTL value. * * @param value the object value to append * @throws IllegalArgumentException if the value is null */ public void appendEscaped(Object value) { if (value == null) { throw new IllegalArgumentException("Null value parameter"); } String string = value.toString(); int length = string.length(); char aChar; for (int i = 0; i < length; i++) { aChar = string.charAt(i); if (ClickUtils.requiresEscape(aChar)) { append(ClickUtils.escapeChar(aChar)); } else { append(aChar); } } } /** * Append the given attribute name and value to the buffer, if the value * is not null. * <p/> * For example: * <pre class="javaCode"> * appendAttribute(<span class="st">"class"</span>, <span class="st">"required"</span>) <span class="green">-></span> <span class="st">class="required"</span> </pre> * * The attribute value will be HMTL escaped. If the attribute name is a * JavaScript event handler the value will not be escaped. * * @param name the HTML attribute name * @param value the object value to append * @throws IllegalArgumentException if name is null */ public void appendAttribute(String name, Object value) { if (name == null) { throw new IllegalArgumentException("Null name parameter"); } if (value != null) { append(" "); append(name); append("=\""); if (isJavaScriptAttribute(name)) { append(value); } else { appendEscaped(value.toString()); } append("\""); } } /** * Append the given HTML attribute name and value to the string buffer. * <p/> * For example: * <pre class="javaCode"> * appendAttribute(<span class="st">"size"</span>, 10) <span class="green">-></span> <span class="st">size="10"</span> </pre> * * @param name the HTML attribute name * @param value the HTML attribute value * @throws IllegalArgumentException if name is null */ public void appendAttribute(String name, int value) { if (name == null) { throw new IllegalArgumentException("Null name parameter"); } append(" "); append(name); append("=\""); append(value); append("\""); } /** * Append the HTML "disabled" attribute to the string buffer. * <p/> * For example: * <pre class="javaCode"> * appendAttributeDisabled() <span class="green">-></span> <span class="st">disabled="disabled"</span> </pre> */ public void appendAttributeDisabled() { append(" disabled=\"disabled\""); } /** * Append the HTML "readonly" attribute to the string buffer. * <p/> * For example: * <pre class="javaCode"> * appendAttributeReadonly() <span class="green">-></span> <span class="st">readonly="readonly"</span> </pre> */ public void appendAttributeReadonly() { append(" readonly=\"readonly\""); } /** * Append the given map of attribute names and values to the string buffer. * * @param attributes the map of attribute names and values * @throws IllegalArgumentException if attributes is null */ public void appendAttributes(Map attributes) { if (attributes == null) { throw new IllegalArgumentException("Null attributes parameter"); } for (Iterator i = attributes.entrySet().iterator(); i.hasNext();) { Map.Entry entry = (Map.Entry) i.next(); String name = entry.getKey().toString(); if (!name.equals("id")) { Object value = entry.getValue(); appendAttribute(name, value); } } } /** * Append the given map of CSS style name and value pairs as a style * attribute to the string buffer. * * @param attributes the map of CSS style names and values * @throws IllegalArgumentException if attributes is null */ public void appendStyleAttributes(Map attributes) { if (attributes == null) { throw new IllegalArgumentException("Null attributes parameter"); } if (!attributes.isEmpty()) { append(" style=\""); for (Iterator i = attributes.entrySet().iterator(); i.hasNext();) { Map.Entry entry = (Map.Entry) i.next(); String name = entry.getKey().toString(); String value = entry.getValue().toString(); append(name); append(":"); append(value); append(";"); } append("\""); } } /** * Append a HTML element end to the string buffer. * <p/> * For example: * <pre class="javaCode"> * elementEnd(<span class="st">"textarea"</span>) <span class="green">-></span> <span class="st"></textarea></span> </pre> * * @param name the HTML element name to end * @throws IllegalArgumentException if name is null */ public void elementEnd(String name) { if (name == null) { throw new IllegalArgumentException("Null name parameter"); } append("</"); append(name); append(">"); } /** * Append a HTML element end to the string buffer. * <p/> * For example: * <pre class="javaCode"> * closeTag() <span class="green">-></span> <span class="st">></span> </pre> * */ public void closeTag() { append(">"); } /** * Append a HTML element end to the string buffer. * <p/> * For example: * <pre class="javaCode"> * elementEnd() <span class="green">-></span> <span class="st">/></span> </pre> * */ public void elementEnd() { append("/>"); } /** * Append a HTML element start to the string buffer. * <p/> * For example: * <pre class="javaCode"> * elementStart(<span class="st">"input"</span>) <span class="green">-></span> <span class="st"><input</span> </pre> * * @param name the HTML element name to start */ public void elementStart(String name) { append("<"); append(name); } /** * Return true if the given attribute name is a JavaScript attribute, * or false otherwise. * * @param name the HTML attribute name to test * @return true if the HTML attribute is a JavaScript attribute */ public boolean isJavaScriptAttribute(String name) { if (name.length() < 6 || name.length() > 11) { return false; } if (!name.startsWith("on")) { return false; } for (int i = 0; i < JS_ATTRIBUTES.length; i++) { if (JS_ATTRIBUTES[i].equalsIgnoreCase(name)) { return true; } } return false; } /** * Return the length of the string buffer. * * @return the length of the string buffer */ public int length() { return count; } /** * @see Object#toString() * * @return a string representation of the string buffer */ public String toString() { return new String(characters, 0, count); } // ------------------------------------------------------ Protected Methods /** * Ensures that the capacity is at least equal to the specified minimum. * If the current capacity is less than the argument, then a new internal * array is allocated with greater capacity. The new capacity is the * larger of: * <ul> * <li>The <code>minimumCapacity</code> argument. * <li>Twice the old capacity, plus <code>2</code>. * </ul> * If the <code>minimumCapacity</code> argument is nonpositive, this method * takes no action and simply returns. * * @param minimumCapacity the minimum desired capacity */ protected void expandCapacity(int minimumCapacity) { int newCapacity = (characters.length + 1) * 2; if (newCapacity < 0) { newCapacity = Integer.MAX_VALUE; } else if (minimumCapacity > newCapacity) { newCapacity = minimumCapacity; } char newValue[] = new char[newCapacity]; System.arraycopy(characters, 0, newValue, 0, count); characters = newValue; } }
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