protected static RevCommit resolveCommitIdByTagName(Repository repository, String tagName)
throws IOException, GitAPIException {
if (tagName == null || tagName.isEmpty()) return null;
RevCommit revCommit = null;
Map<String, Ref> tagMap = repository.getTags();
Ref ref = tagMap.get(tagName);
if (ref != null) {
RevWalk walk = new RevWalk(repository);
// some reduce memory effors as described in jgit user guide
walk.setRetainBody(false);
ObjectId from;
from = repository.resolve("refs/heads/master");
if (from == null) {
Git git = new Git(repository);
String lastTagName = git.describe().call();
from = repository.resolve("refs/tags/" + lastTagName);
}
ObjectId to = repository.resolve("refs/remotes/origin/master");
if (from == null) {
throw new IllegalStateException("cannot determinate start commit");
}
walk.markStart(walk.parseCommit(from));
walk.markUninteresting(walk.parseCommit(to));
try {
RevObject revObject = walk.parseAny(ref.getObjectId());
if (revObject != null) {
revCommit = walk.parseCommit(revObject.getId());
}
} finally {
walk.close();
}
}
return revCommit;
}
