test/packed/Benchmark.java

package packed;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.IntBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;
import java.util.Random;
import java.util.logging.Logger;

/**
 * This program runs a little benchmark to check reading speed on various data
 * representations.
 * 
 * Usage: java Benchmark PACKED_GRAMMAR_DIR TIMES
 */

public class Benchmark {
	private static final Logger	logger = Logger.getLogger(Benchmark.class.getName());

	private IntBuffer intBuffer;
	private MappedByteBuffer byteBuffer;
	private int[] intArray;

	public Benchmark(String dir) throws IOException {
		File file = new File(dir + "/slice_00000.source");
		
		FileChannel source_channel = new FileInputStream(file).getChannel();
		int byte_size = (int) source_channel.size();
		int int_size = byte_size / 4;
		
		byteBuffer = source_channel.map(MapMode.READ_ONLY, 0, byte_size); 
		intBuffer = byteBuffer.asIntBuffer();
		
		intArray = new int[int_size];
		intBuffer.get(intArray);
	}
	
	public void benchmark(int times) {
		logger.info("Beginning benchmark.");
		
		Random r = new Random();
		r.setSeed(1234567890);
		int[] positions = new int[1000];
		for (int i = 0; i < positions.length; i++)
			positions[i] = r.nextInt(intArray.length);
		
		long sum;
		
		long start_time = System.currentTimeMillis();
		
		sum = 0;
		for (int t = 0; t < times; t++)
			for (int i = 0; i < positions.length; i++)
				sum += byteBuffer.getInt(positions[i] * 4);
		logger.info("Sum: " + sum);
		long byte_time = System.currentTimeMillis();
		
		sum = 0;
		for (int t = 0; t < times; t++)
			for (int i = 0; i < positions.length; i++)
				sum += intBuffer.get(positions[i]);
		logger.info("Sum: " + sum);
		long int_time = System.currentTimeMillis();
		
		sum = 0;
		for (int t = 0; t < times; t++)
			for (int i = 0; i < positions.length; i++)
				sum += intArray[positions[i]];
		logger.info("Sum: " + sum);
		long array_time = System.currentTimeMillis();
		
		sum = 0;
		for (int t = 0; t < times; t++)
			for (int i = 0; i < (intArray.length / 8); i++)
				sum += intArray[i * 6] + intArray[i * 6 + 2];
		logger.info("Sum: " + sum);
		long mult_time = System.currentTimeMillis();

		sum = 0;
		for (int t = 0; t < times; t++) {
			int index = 0;
			for (int i = 0; i < (intArray.length / 8); i++) {
				sum += intArray[index] + intArray[index + 2];
				index += 6;
			}
		}
		logger.info("Sum: " + sum);
		long add_time = System.currentTimeMillis();
		
		logger.info("ByteBuffer: " + (byte_time - start_time));
		logger.info("IntBuffer:  " + (int_time - byte_time));
		logger.info("Array:      " + (array_time - int_time));
		logger.info("Multiply:   " + (mult_time - array_time));
		logger.info("Add:        " + (add_time - mult_time));
	}

	public static void main(String args[]) throws IOException {
		Benchmark pr = new Benchmark(args[0]);
		pr.benchmark( Integer.parseInt(args[1]));
	}
}