Don't log non-db error in retry wrapper

838e314a21fef9ca6cf99140b2400e0d3b68b109 changed the retry wrapper
code to not log exception traces for expected errors, like when
retrying on a DBDeadlock. It did, however, log an unexpected exception
but was not checking the type, like in the case of a nova OverQuota
exception.

Since _is_execption_expected already logs at debug level an expected
DB error, like DBDeadlock, during a retry loop, we don't need to log
it again. And if the exception is unexpected, like OverQuota from nova,
then we shouldn't trace that exception in the retry loop before
reraising but instead just let the caller handle it.

Adds a unit test to make sure that nothing is logged in the unexpected
exception case during the retry loop.

Co-Authored-By: Sean Dague <sean@dague.net>

Change-Id: Ic3e45029378dc96ce01398d9b55f51e20ef08189
Closes-Bug: #1532880

2 files changed, 12 insertions, 5 deletions

diff --git a/oslo_db/api.py b/oslo_db/api.py
index dcba2a3..ea1d41d 100644
--- a/oslo_db/api.py
+++ b/oslo_db/api.py
@@ -139,11 +139,6 @@ class wrap_db_retry(object):
                     with excutils.save_and_reraise_exception() as ectxt:
                         if remaining > 0:
                             ectxt.reraise = not self._is_exception_expected(e)
-                            if ectxt.reraise:
-                                # We got an unexpected exception so stop
-                                # retrying, log it and raise it up to the
-                                # caller.
-                                LOG.exception(_LE('DB error.'))
                         else:
                             LOG.exception(_LE('DB exceeded retry limit.'))
                             # if it's a RetryRequest, we need to unpack it
diff --git a/oslo_db/tests/test_api.py b/oslo_db/tests/test_api.py
index 56d5529..d3e9834 100644
--- a/oslo_db/tests/test_api.py
+++ b/oslo_db/tests/test_api.py
@@ -220,3 +220,15 @@ class DBRetryRequestCase(DBAPITestCase):
         dbapi.api_class_call1()
 
         self.assertFalse(mocked_wrap.called)
+
+    @mock.patch('oslo_db.api.LOG')
+    def test_retry_wrapper_non_db_error_not_logged(self, mock_log):
+        # Tests that if the retry wrapper hits a non-db error (raised from the
+        # wrapped function), then that exception is reraised but not logged.
+
+        @api.wrap_db_retry(max_retries=5, retry_on_deadlock=True)
+        def some_method():
+            raise AttributeError('test')
+
+        self.assertRaises(AttributeError, some_method)
+        self.assertFalse(mock_log.called)