fix(hybridcloud) Clear lookup state during initialization (#50166)

This avoids leaking state between instances of the SiloRouter which was
impacting getsentry tests.

src/sentry/db/router.py

@@ -39,6 +39,7 @@ class SiloRouter:
  """Whether or not we're operating in a simulated silo environment"""
 
  def __init__(self):
+ self.__table_to_silo = {}
  try:
  # By accessing the connections Django will raise
  # Use `assert` to appease linters
@@ -89,7 +90,9 @@ def _db_for_table(self, table, app_label):
  # have to scan through models more than once.
  self.__table_to_silo[table] = self._db_for_model(model)
 
- return self.__table_to_silo[table]
+ # All actively used tables should be in this map, but we also
+ # need to handle tables in migrations that no longer exist.
+ return self.__table_to_silo.get(table, "default")
 
  def db_for_read(self, model, **hints):
  return self._db_for_model(model)

tests/sentry/db/test_router.py

@@ -24,6 +24,11 @@ def test_for_control(self):
  assert router.allow_migrate("control", "sentry", User)
  assert not router.allow_migrate("region", "sentry", User)
 
+ # Ensure tables that no longer exist don't fail
+ assert router.allow_migrate(
+ "default", "sentry", model=None, hints={"tables": ["jira_ac_tenant"]}
+ )
+
  @override_settings(SILO_MODE="REGION")
  def test_for_region(self):
  router = SiloRouter()