Push pending tag and synthesized commit in a single git push operation.

infra/services/gnumbd/gnumbd.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Gnumd (Git NUMber Daemon): Adds metadata to git commits as they land in
 a primary repo.
 
 This is a simple daemon which takes commits pushed to a pending ref, alters
 their message with metadata, and then pushes the altered commits to a parallel
 ref.
@@ skipping 244 matching lines @@
     i += 1
 
   if i > 0:
     logging.warn('Catching up pending_tag %r (was %d behind)', pending_tag, i)
     new_tag_val = new_commits[i-1]
     if content_of(new_tag_val) != content_of(real_ref.commit):
       LOGGER.error('Content of new tag %r does not match content of %r!',
                    new_tag_val.hsh, real_ref.commit.hsh)
       return []
     new_commits = new_commits[i:]
-    pending_tag.fast_forward_push(new_tag_val)
+    pending_tag.repo.fast_forward_push({pending_tag: new_tag_val})
 
   if not new_commits:
     LOGGER.warn('Tag was lagging for %r by %d, but no new commits are pending',
                 real_ref, len(new_commits))
     return []
 
   return new_commits
 
 
 def process_ref(real_ref, pending_tag, new_commits, clock=time):
@@ skipping 19 matching lines @@
   @type real_ref: git2.Ref
   @type pending_tag: git2.Ref
   @type new_commits: [git2.Commit]
   @kind clock: implements .time(), used for testing determinisim.
   """
   # TODO(iannucci): use push --force-with-lease to reset pending to the real
   # ref?
   # TODO(iannucci): The ACL rejection message for the real ref should point
   # users to the pending ref.
   assert content_of(pending_tag.commit) == content_of(real_ref.commit)
+  assert real_ref.repo == pending_tag.repo
+  repo = real_ref.repo
   real_parent = real_ref.commit
   for commit in new_commits:
     assert content_of(commit.parent) == content_of(real_parent)
     synth_commit = synthesize_commit(commit, real_parent, real_ref, clock)
 
-    # TODO(iannucci):  do multi-ref atomic push here.
-    logging.info('Pushing synthesized commit %r for %r', synth_commit.hsh,
-                 commit.hsh)
-    real_ref.fast_forward_push(synth_commit)
+    logging.info(
+        'Pushing synthesized commit %r for %r and pending_tag %r',
+        synth_commit.hsh, commit.hsh, pending_tag)
+    repo.fast_forward_push({
+      real_ref: synth_commit,
+      pending_tag: commit,
+    })
 
-    logging.debug('Pushing pending_tag %r', pending_tag)
-    pending_tag.fast_forward_push(commit)
     real_parent = synth_commit
 
 
 def process_repo(repo, cref, clock=time):
   """Execute a single pass over a fetched Repo.
 
   Will call |process_ref| for every branch indicated by the enabled_refglobs
   config option.
   """
   pending_tag_prefix = cref['pending_tag_prefix']
@@ skipping 36 matching lines @@
         LOGGER.error('%s %s', e.__class__.__name__, e)
       except Exception:  # pragma: no cover
         LOGGER.exception('Uncaught exception while processing %r', real_ref)
 
 
 def inner_loop(repo, cref, clock=time):
   LOGGER.debug('fetching %r', repo)
   repo.run('fetch', stdout=sys.stdout, stderr=sys.stderr)
   cref.evaluate()
   process_repo(repo, cref, clock)