Benchmark.java

// BenchMark.java -- 
// Copyright (c)2008 Christopher League <league@contrapunctus.net>

// This is free software, but it comes with ABSOLUTELY NO WARRANTY.
// GNU Lesser General Public License 2.1 or Common Public License 1.0

package net.contrapunctus.lzma;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Random;
import java.util.zip.Adler32;
import java.util.zip.Checksum;

public class Benchmark
{
    private static byte[][]       data       = null;
    private static final Random   rnd        = new Random(0xCAFEBABE);
    private static final Checksum ck         = new Adler32();
    private static final int      EXPONENT   = 18;
    private static final int      ITERATIONS = 512;
    private static final int      BUFSIZE    = 8192;
    
    static
    {
        data = new byte[EXPONENT][];
        int num = 1;
        for (int i = 0; i < data.length; i++, num *= 2)
        {
            data[i] = new byte[num];
            rnd.nextBytes(data[i]);
        }
    }
    
    public static void doit() throws IOException
    {
        final ByteArrayOutputStream baos = new ByteArrayOutputStream();
        final LzmaOutputStream lo = new LzmaOutputStream(baos);
        int byteCount = 0;
        for (int i = 0; i < ITERATIONS; i++)
        {
            final int k = rnd.nextInt(data.length);
            lo.write(data[k]);
            ck.update(data[k], 0, data[k].length);
            byteCount += data[k].length;
        }
        lo.close();
        byte[] buf = baos.toByteArray();
        final long sum = ck.getValue();
        System.out.printf(
                "%d bytes written, %d bytes compressed, checksum %X\n",
                byteCount, buf.length, sum);
        
        // and back again
        final ByteArrayInputStream bais = new ByteArrayInputStream(buf);
        final LzmaInputStream li = new LzmaInputStream(bais);
        buf = new byte[BUFSIZE];
        ck.reset();
        int k = li.read(buf);
        byteCount = 0;
        while (k > 0)
        {
            byteCount += k;
            ck.update(buf, 0, k);
            k = li.read(buf);
        }
        System.out.printf("%d bytes decompressed, checksum %X\n", byteCount,
                ck.getValue());
        li.close();
        assert sum == ck.getValue();
    }
    
    public static void main(String[] args) throws IOException
    {
        final long start = System.nanoTime();
        doit();
        long elapsed = System.nanoTime() - start;
        elapsed /= 1000;
        System.out.printf("%d us elapsed\n", elapsed);
    }
}