Merge lp:~cjwatson/launchpad/git-optimise-empty-commits into lp:launchpad

[Colin Watson]

Optimise GitRepository.fetchRefCommits if there are no commits to fetch.

This seems rather common in practice (e.g. a push that just deletes refs), so we might as well save a request.

[William Grant (wgrant)]

review: Approve (code)

=== modified file 'lib/lp/code/model/gitrepository.py'
--- lib/lp/code/model/gitrepository.py	2018-07-13 09:17:40 +0000
+++ lib/lp/code/model/gitrepository.py	2018-07-24 12:25:11 +0000
@@ -676,6 +676,8 @@
     def fetchRefCommits(hosting_path, refs, logger=None):
         """See `IGitRepository`."""
         oids = sorted(set(info["sha1"] for info in refs.values()))
+        if not oids:
+            return
         commits = parse_git_commits(
             getUtility(IGitHostingClient).getCommits(
                 hosting_path, oids, logger=logger))

=== modified file 'lib/lp/code/model/tests/test_gitrepository.py'
--- lib/lp/code/model/tests/test_gitrepository.py	2017-11-06 09:32:45 +0000
+++ lib/lp/code/model/tests/test_gitrepository.py	2018-07-24 12:25:11 +0000
@@ -1337,6 +1337,13 @@
             }
         self.assertEqual(expected_refs, refs)
 
+    def test_fetchRefCommits_empty(self):
+        # If given an empty refs dictionary, fetchRefCommits returns early
+        # without contacting the hosting service.
+        hosting_fixture = self.useFixture(GitHostingFixture())
+        GitRepository.fetchRefCommits("dummy", {})
+        self.assertEqual([], hosting_fixture.getCommits.calls)
+
     def test_synchroniseRefs(self):
         # synchroniseRefs copes with synchronising a repository where some
         # refs have been created, some deleted, and some changed.