BigText.java

/* Copyright 2004 Elliotte Rusty Harold
   
   This library is free software; you can redistribute it and/or modify
   it under the terms of version 2.1 of the GNU Lesser General Public 
   License as published by the Free Software Foundation.
   
   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
   GNU Lesser General Public License for more details.
   
   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, write to the 
   Free Software Foundation, Inc., 59 Temple Place, Suite 330, 
   Boston, MA 02111-1307  USA
   
   You can contact Elliotte Rusty Harold by sending e-mail to
   elharo@metalab.unc.edu. Please include the word "XOM" in the
   subject line. The XOM home page is located at http://www.xom.nu/
*/

package nu.xom.benchmarks;

import java.io.IOException;
import java.text.DecimalFormat;

import nu.xom.Builder;
import nu.xom.Document;
import nu.xom.Element;
import nu.xom.ParsingException;

/**
 * <p>
 * Simple memory benchmark focusing on a big document
 * with lots of text covering all of Unicode.
 * </p>
 * 
 * @author Elliotte Rusty Harold
 * @version 1.1.1b1
 *
 */
class BigText {

    static Document makeFullUnicode() {
        
        Element root = new Element("root");
        Document doc = new Document(root);           

        StringBuffer sb = new StringBuffer(65536);
        for (int i = 0x20; i <= 0xD7FF; i++) {
            sb.append((char) i);
        }
        
        // skip surrogates between 0xD800 and 0xDFFF
        
        for (int i = 0xE000; i <= 0xFFFD; i++) {
            sb.append((char) i);
        }
        
        System.gc();

        // Plane-1 characters are tricky because Java 
        // strings  encode them as surrogate pairs. First, fill  
        // a byte array with the characters from 1D100 to 1D1FF 
        // (the musical symbols)
        for (int i = 0; i < 256; i++) {
            // algorithm from RFC 2781
            int u = 0x1D100 + i;
            int uprime = u - 0x10000;
            int W1 = 0xD800;
            int W2 = 0xDC00;
            W2 = W2 | (uprime & 0x7FF );
            W1 = W1 | (uprime & 0xFF800);
            sb.append( ((char) W1) );
            sb.append( ((char) W2) );
        }
        
        root.appendChild(sb.toString());
        
        return doc;
        
    }

    public static void main(String[] args) 
      throws IOException, ParsingException {
        
        DecimalFormat format = new DecimalFormat();
        format.setMaximumFractionDigits(2);
        Runtime r = Runtime.getRuntime();
        System.gc(); System.gc(); System.gc();
        long before = r.totalMemory() - r.freeMemory();
        Document doc;
        if (args.length > 0) {
            Builder builder = new Builder();
            doc = builder.build(args[0]); 
            builder = null;  
        }
        else {
            doc = makeFullUnicode();
        }
        long after = r.totalMemory() - r.freeMemory();
        double usage = (after - before)/(1024.0*1024.0);
        System.out.println("Memory used: " 
          + format.format(usage) + "M");
        System.gc(); System.gc(); System.gc();
        long postGC = r.totalMemory() - r.freeMemory();
        usage = (postGC - before)/(1024.0*1024.0);
        System.out.println("Memory used after garbage collection: " 
          + format.format(usage) + "M");
       
        // Make sure the document isn't prematurely garbage collected
        System.out.println("Meaningless number: " 
          + doc.toXML().length());
    }

}