private async RecursiveCallResult <Commit?> ReferenceOrCopyCommitImpl(
Repository sourceRepo,
Commit commit,
Repository targetRepo,
int maxDepth)
{
if (maxDepth == 0)
{
return(null);
}
// fastest way: use copied commit
if (TryGetCopiedCommit(commit, targetRepo, out var newCommit))
{
return(newCommit);
}
switch (_callback.GetCommitCopyKind(commit))
{
case CommitCopyKind.NoCommit:
{
// if source tree not found: this commit will be parent of top commit.
newCommit = null;
}
break;
case CommitCopyKind.UseParent:
{
// if maxDepth == 1 means deepest commit: parent never exists so force copy commit
if (maxDepth == 1)
{
goto case CommitCopyKind.CopyCommit;
}
// if no difference: this commit is same as parent's commit
_progressHandler?.OnFoundNewCommit(1);
newCommit = await ReferenceOrCopyCommit(sourceRepo, commit.Parents.First(), targetRepo,
NextDepth(maxDepth));
}
break;
case CommitCopyKind.CopyCommit:
{
// otherwise: copies commit
// Count() will be fast because Parents implements Collection
var parentCount = commit.Parents.Count();
_progressHandler?.OnFoundNewCommit(parentCount);
Commit[] parentArray = new Commit[parentCount];
var parentsIndex = 0;
RecursiveCallResult <Commit?>[] promises = new RecursiveCallResult <Commit?> [parentCount];
var promisesIndex = 0;
foreach (var commitParent in commit.Parents)
{
promises[promisesIndex++] =
ReferenceOrCopyCommit(sourceRepo, commitParent, targetRepo, NextDepth(maxDepth));
}
foreach (var promise in promises)
{
var newParent = await promise;
if (newParent != null)
{
parentArray[parentsIndex++] = newParent;
}
}
Commit[] parents = parentArray.AsSpan().Slice(0, parentsIndex).ToArray();
targetRepo.Index.Clear();
var targetRepoIndexTree = _callback.CreateCommitTree(commit, parents, targetRepo);
var message = _callback.GenerateCommitMessage(commit);
var author = commit.Author;
var committer = commit.Committer;
newCommit = targetRepo.ObjectDatabase.CreateCommit(author, committer, message,
targetRepoIndexTree, parents, false);
_objectMapping[newCommit.Id] = commit.Id;
}
break;
default:
throw new ArgumentOutOfRangeException("", "result of GetCommitCopyKind");
}
_objectMapping[commit.Id] = newCommit?.Id ?? PreDefinedHash.EmptyTreeId;
return(newCommit);
}