jgit pack-indexing performance test

IndexPackPerformanceTest.java

package org.eclipse.jgit.transport;

import org.eclipse.jgit.lib.NullProgressMonitor;
import org.eclipse.jgit.lib.RepositoryTestCase;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import static java.util.Arrays.asList;

public class IndexPackPerformanceTest extends RepositoryTestCase {

    public void testIndexingPerformanceVsStreamThresholdSize() throws IOException {
        final String[] packFilePaths = {
                "/home/roberto/development/google-guice-git/.git/objects/pack/pack-7da01e4809d62bb98f271bb65c40f286edc20b48.pack",
                "/home/roberto/development/glug/.git/objects/pack/pack-eeb4b313214ece7599b8e778deb8b4c17b168f03.pack",
                "/home/roberto/development/jgit/org.eclipse.jgit.test/tst-rsrc/org/eclipse/jgit/test/resources/pack-cbdeda40019ae0e6e789088ea0f51f164f489d14.pack",
                "/home/roberto/kdenlive-upgrade/x264/.git/objects/pack/pack-cab2cef0f4b52ec3c137f1e2912877cf2230e3b9.pack",
                "/home/roberto/android-repos/.repo/projects/external/webkit.git/objects/pack/pack-cccd4f5de08fd45ef4fe3875649cae6db3052fdf.pack"
        };
        List<Integer> streamThresholdMagnitudes=asList(0, 2, 4, 6, 8, 10, 12, 14, 16, 20, 22 );
        int repeats=10;
        List<Integer> testList=new ArrayList<Integer>();
        for (int i=0;i<repeats;++i) {
            testList.addAll(streamThresholdMagnitudes);
        }
        Collections.shuffle(testList);
        System.out.print("testNum,magnitude");
        for (String packFilePath : packFilePaths) {
            final File file = new File(packFilePath);
            System.out.print(","+ file.getName()+" ("+file.length()+" bytes)");
        }
        System.out.println();
        for (int testNum=0;testNum<testList.size(); ++testNum) {
            final Integer magnitude = testList.get(testNum);
            System.out.print(testNum+","+magnitude);
            for (String packFilePath : packFilePaths) {
                long duration=execute(new File(packFilePath), testNum, magnitude);
                System.out.print(","+duration);
                try {
                    Thread.sleep(1000L); // allow any resulting GC to finish
                } catch (InterruptedException e) {}
            }
            System.out.println();
        }
	}

    private long execute(File packFile, int testNum, int streamThresholdMagnitude) throws IOException {
        InputStream is = new FileInputStream(packFile);
        try {
            long start=System.currentTimeMillis();

            IndexPack pack = new IndexPack(db, is, new File(trash,"tmp_pack_perf_"+packFile.getName()+"_run_" + streamThresholdMagnitude + "_" + testNum));
            pack.setStreamFileThreshold(1<<streamThresholdMagnitude);
            pack.index(NullProgressMonitor.INSTANCE);
            return System.currentTimeMillis()-start;
        } finally {
            is.close();
        }
    }
}

The data generated by this test is at https://spreadsheets.google.com/ccc?key=tLCQElyyd2RKN9QevfvgwGQ&hl=en_GB#gid=1

These performance tests relate to JGit Change I862afd4c - http://egit.eclipse.org/r/2040 (IndexPack: Use streaming for large whole blobs) - which is the fix for https://bugs.eclipse.org/bugs/show_bug.cgi?id=312868 (java.lang.OutOfMemoryError when fetching objects bigger than heap size)