schema-agreement: cap mismatch retry sleep

Author: dkropachev

cassandra/cluster.py

@@ -4270,7 +4270,9 @@ def wait_for_schema_agreement(self, connection=None, preloaded_results=None, wai
                     return True
 
                 log.debug("[control connection] Schemas mismatched, trying again")
-                self._time.sleep(0.2)
+                remaining = total_timeout - elapsed
+                if remaining > 0:
+                    self._time.sleep(min(0.2, remaining))
                 elapsed = self._time.time() - start
 
             log.warning("Node %s is reporting a schema disagreement: %s",

tests/unit/test_control_connection.py

@@ -370,19 +370,12 @@ def test_schema_change_refresh_does_not_session_fallback_after_mismatch_then_con
         assert not response_future.is_schema_agreed
         response_future._set_final_result.assert_called_once_with(None)
 
-    def test_wait_for_schema_agreement_does_not_exceed_configured_wait_with_session_fallback(self):
-        session = Mock(is_shutdown=False)
-
-        def wait_for_schema_agreement(wait_time=None):
-            self.time.sleep(wait_time)
-            return False
-
-        session.wait_for_schema_agreement.side_effect = wait_for_schema_agreement
-        self.cluster.sessions = [session]
+    def test_wait_for_schema_agreement_does_not_sleep_past_deadline_after_mismatch(self):
+        self.cluster.max_schema_agreement_wait = 0.1
         self.connection.peer_results[1][1][2] = 'b'
 
         assert not self.control_connection.wait_for_schema_agreement()
-        assert self.time.clock < self.cluster.max_schema_agreement_wait + 0.2
+        assert self.time.clock == self.cluster.max_schema_agreement_wait
 
     def test_wait_for_schema_agreement_skipping(self):
         """