def _handle_quorum(self, quorum: int, quorum_timeout: int,
options: dict) -> Iterator[bool]:
"""
Context manager that handles migration application quorum by only
allowing a single caller to proceed with application and preventing
exit attempts until the application is completes.
This ensures only a single invocation is allowed to proceed once
quorum is reached and that context can only be exited once the
invocation application succeeds.
"""
if quorum < 2:
yield True
return
verbosity = options["verbosity"]
plan = self._get_plan(**options)
if not plan:
yield True
return
database = options["database"]
plan_hash = hash_plan(plan)
pre_namespace = f"pre:{database}:{plan_hash}"
post_namespace = f"post:{database}:{plan_hash}"
if join_quorum(pre_namespace, quorum):
if verbosity:
self.stdout.write(
"Reached pre-migrate quorum, proceeding with planned migrations..."
)
yield True
if verbosity:
self.stdout.write("Waiting for post-migrate quorum...")
duration = self._join_or_poll_until_quorum(post_namespace, quorum,
quorum_timeout)
if verbosity:
self.stdout.write(
f"Reached post-migrate quorum after {duration:.2f}s...")
return
yield False
if verbosity:
self.stdout.write("Waiting for pre-migrate quorum...")
duration = self._poll_until_quorum(pre_namespace, quorum,
quorum_timeout)
if verbosity:
self.stdout.write(
f"Reached pre-migrate quorum after {duration:.2f}s...")
self.stdout.write(
"Waiting for migrations to be applied by remote party...")
duration = self._join_or_poll_until_quorum(post_namespace, quorum,
quorum_timeout)
if verbosity:
self.stdout.write(
f"Reached post-migrate quorum after {duration:.2f}s...")
self.stdout.write("Migrations applied by remote party")
return
def test_app_label(self):
test_app = (Migration("0001_initial", "tests"), True)
other_app = (Migration("0001_initial", "other"), True)
self.assertNotEqual(hash_plan([test_app]), hash_plan([other_app]))
def test_backward(self):
forward = (Migration("0001_initial", "tests"), True)
backward = (Migration("0001_initial", "tests"), False)
self.assertNotEqual(hash_plan([forward]), hash_plan([backward]))
def test_migration_name(self):
first = (Migration("0001_initial", "tests"), True)
second = (Migration("0002_second", "tests"), True)
self.assertNotEqual(hash_plan([first]), hash_plan([second]))
def test_stable(self):
plan = [(Migration("0001_initial", "tests"), True)]
self.assertEqual(hash_plan(plan),
"a4a35230c7d1942265f1bc8f9ce53e05a50848be")