为什么jGit的RevWalk.reset（）方法行为不端？

Question

假设我们在git存储库中有两个文件，path / to / file1.txt和path / to / file2.txt。 file1.txt首先提交，然后是file2.txt，因此它们属于具有不同SHA1的提交。我想使用jGit检索与每个文件对应的SHA1。这是我到目前为止的代码：

String localPath = "/path/to/repo";
Repository localRepo = new FileRepository(localPath + "/.git");

Ref headRef = localRepo.getRef("refs/heads/master");
RevWalk revWalk = new RevWalk(localRepo);
RevCommit headCommit = revWalk.parseCommit(headRef.getObjectId());
TreeWalk tw = new TreeWalk(localRepo);
tw.addTree(headCommit.getTree());
tw.setRecursive(true);

HashMap<String, String> fileShas = new HashMap<String, String>();
RevWalk commitFinder = new RevWalk(localRepo);

while (tw.next()) {
  ArrayList<PathFilter> filters = new ArrayList<PathFilter>();
  filters.add(PathFilter.create(tw.getPathString()));

  commitFinder.reset();
  RevCommit iterHead = commitFinder.lookupCommit(headRef.getObjectId());
  commitFinder.markStart(iterHead);
  commitFinder.setTreeFilter(AndTreeFilter.create(PathFilterGroup.create(filters), TreeFilter.ANY_DIFF));
  commitFinder.setRevFilter(MaxCountRevFilter.create(1));

  RevCommit commit = commitFinder.next();
  fileShas.put(tw.getPathString(), commit.getId().getName());
}

不幸的是，这不起作用。我得到第一个文件的正确SHA1，但不是第二个文件。看来commitFinder.reset();没有做好自己的工作。如果我在每次迭代时创建一个新的RevWalk，它可以工作，但速度非常慢。有什么想法reset()无效？

Answer 1

虽然这并没有回答这个问题，但我把调查结果放在这里是为了提高可读性。下面显示的测试中的getLatestModification方法返回上次修改给定文件的提交的id。

虽然代码比原始代码段短，但问题仍然是reset显然无法正常工作。

public class RevWalkResetLearningTest {

  @Rule
  public final TemporaryFolder tempFolder = new TemporaryFolder();

  private Repository repository;

  @Test
  public void testReset() throws Exception {
    RevWalk revWalk = new RevWalk( repository );
    RevCommit beerCommit = getLastModification( revWalk, "plugins/emoji/public/images/beer.png" );
//    RevCommit discourseCommit = getLastModification( new RevWalk( repository ), "images/discourse.png" );
    RevCommit discourseCommit = getLastModification( revWalk, "images/discourse.png" );

    assertEquals( "8278fdb9ddbc61eea9f6e6045b705106678ce532", beerCommit.name() );
    assertEquals( "50cd44df2dec27c0834be4a2975fe175c3fac64f", discourseCommit.name() );
  }

  private RevCommit getLastModification( RevWalk revWalk, String path ) throws IOException {
    revWalk.reset();
    revWalk.markStart( revWalk.parseCommit( repository.resolve( "refs/heads/master" ) ) );
    revWalk.setTreeFilter( AndTreeFilter.create( PathFilter.create( path ), TreeFilter.ANY_DIFF ) );
    return revWalk.next();
  }

  @Before
  public void setUp() throws Exception {
//    Git git = Git.cloneRepository().setURI( "https://github.com/discourse/discourse.git" ).setDirectory( tempFolder.getRoot() ).call();
//    repository = git.getRepository();
    repository = new FileRepositoryBuilder().setMustExist( true ).setGitDir( new File( "/path/to/discourse/.git" ) ).build();
  }

  @After
  public void tearDown() {
    repository.close();
  }
}

测试失败，因为discourseCommit的commit-id与beerCommit相同。如果我更改代码以便每次调用getLastModification获得RevWalk的新实例（请参阅注释行），则测试成功。

我建议打开bug report或向JGit mailing list寻求帮助。