[jgit-dev] question about commits/trees/parents

[Markus Duft <markus.duft@xxxxxxxxxx>]

Hi!

I'm writing a short peace of code, that should give me the size of all files touched in the last commit. for this reason i'm using a treewalk with an ANY_DIFF filter (is this the right approach?) and intend to pass the trees of the current and the parent RevCommit.

walk.setFilter(TreeFilter.ANY_DIFF);
walk.reset(commit.getParent(0).getTree(), commit.getTree());

now, in this case i have these evaluations when hitting the reset() line:

 commit = commit 4e408bb4f8e84240c19ddfe4ea2d97fdc6996856 1336045390 -----p
 commit.getParent(0) = commit 6c88f48e66c953e0c50167378377e8e3273d2ffe 0 ------

calling any getter on the parent (like getTree()) yields null or NPE... what am i doing wrong? i'm using plain jgit as library in a plain java application. the whole code looks like this:

    /**
     * Investigates files changed by the commit referenced by the patchset of the given event, and
     * returns a map of paths to file sizes for files that are too large.
     */
    public Map<String, Long> getInvalidSizedFiles(GerritBaseChangeEvent e) {
        try {
            RevCommit commit = getCommit(e);
            if (commit == null) {
                throw new IllegalStateException("cannot find commit for event " + e);
            }

            if (commit.getParentCount() != 1) {
                throw new IllegalStateException("commit " + commit + " has not exactly one parent!");
            }

            // since the actual commit is added as second tree, from now on, index '1' refers to the
            // actual commit.
            TreeWalk walk = new TreeWalk(repo);
            walk.setFilter(TreeFilter.ANY_DIFF);
            walk.reset(commit.getParent(0).getTree(), commit.getTree());
            walk.setRecursive(true);

            ObjectReader reader = walk.getObjectReader();

            Map<String, Long> result = new TreeMap<String, Long>();

            try {
                while (walk.next()) {
                    String path = walk.getPathString();

                    FileMode newMode = walk.getFileMode(1);
                    if (newMode.equals(FileMode.TYPE_FILE)) {
                        long size = reader.getObjectSize(walk.getObjectId(1), Constants.OBJ_BLOB);

                        if (size > config.getValidationFszWarn()
                                || size > config.getValidationFszError()) {
                            result.put(path, size);
                        }
                    }
                }
            } finally {
                reader.release();
            }

            return result;
        } catch (Exception ex) {
            log.error("failed to get file sizes for " + e, ex);
            return Collections.emptyMap();
        }
    }

    /**
     * Searches for the commit object associated with the given Gerrit event. If no commit can be
     * found, <code>null</code> is returned.
     */
    public RevCommit getCommit(GerritBaseChangeEvent e) {
        GerritPatchset p = e.getPatchset();

        if (p == null) {
            return null;
        }

        String rev = p.getRevision();
        try {
            RevWalk walk = new RevWalk(repo);
            return walk.parseCommit(getOidForRev(rev));
        } catch (Exception ex) {
            log.error("cannot find commit with id " + rev, ex);
            return null;
        }
    }


    /**
     * Returns the {@link ObjectId} for the given RevString, which may be any valid GIT revision ID.
     * If the given revision is not found in the repository, <code>null</code> is returned.
     * 
     * @param rev
     *            the revision to resolve
     * @return the {@link ObjectId} or <code>null</code> if not found.
     */
    public ObjectId getOidForRev(String rev) {
        try {
            return repo.resolve(rev);
        } catch (Exception e) {
            log.error("cannot resolve rev " + rev, e);
        }

        return null;
    }

Thanks for helping in advance :)

Regards,
Markus