git_remote_helpers/fastimport/head_tracker.py

   1
   2
   3 class HeadTracker(object):
   4     """
   5     Keep track of the heads in a fastimport stream.
   6     """
   7     def __init__(self):
   8         self.last_ref = None
   9
  10         # map git ref name (e.g. "refs/heads/master") to id of last
  11         # commit with that ref
  12         self.last_ids = {}
  13
  14         # the set of heads seen so far in the stream, as a mapping
  15         # from commit id of the head to set of ref names
  16         self.heads = {}
  17
  18     def track_heads(self, cmd):
  19         """Track the repository heads given a CommitCommand.
  20
  21         :param cmd: the CommitCommand
  22         :return: the list of parents in terms of commit-ids
  23         """
  24         # Get the true set of parents
  25         if cmd.from_ is not None:
  26             parents = [cmd.from_]
  27         else:
  28             last_id = self.last_ids.get(cmd.ref)
  29             if last_id is not None:
  30                 parents = [last_id]
  31             else:
  32                 parents = []
  33         parents.extend(cmd.merges)
  34
  35         # Track the heads
  36         self.track_heads_for_ref(cmd.ref, cmd.id, parents)
  37         return parents
  38
  39     def track_heads_for_ref(self, cmd_ref, cmd_id, parents=None):
  40         if parents is not None:
  41             for parent in parents:
  42                 if parent in self.heads:
  43                     del self.heads[parent]
  44         self.heads.setdefault(cmd_id, set()).add(cmd_ref)
  45         self.last_ids[cmd_ref] = cmd_id
  46         self.last_ref = cmd_ref
  47