Merge pull request #2040 from daspecster/retry-system3-tests

Playing with retries.

system_tests/bigquery.py

@@ -20,7 +20,9 @@
 from gcloud import _helpers
 from gcloud.environment_vars import TESTS_PROJECT
 from gcloud import bigquery
+from gcloud.exceptions import Forbidden
 
+from retry import Retry
 from system_test_utils import unique_resource_id
 
 
@@ -90,7 +92,15 @@ def test_update_dataset(self):
         after = [grant for grant in dataset.access_grants
                  if grant.entity_id != 'projectWriters']
         dataset.access_grants = after
-        dataset.update()
+
+        # We need to wait to stay within the rate limits.
+        # The alternative outcome is a 403 Forbidden response from upstream.
+        # See: https://cloud.google.com/bigquery/quota-policy
+        @Retry(Forbidden, tries=2, delay=30)
+        def update_dataset():
+            dataset.update()
+
+        update_dataset()
         self.assertEqual(len(dataset.access_grants), len(after))
         for found, expected in zip(dataset.access_grants, after):
             self.assertEqual(found.role, expected.role)
@@ -188,7 +198,15 @@ def test_patch_table(self):
     def test_update_table(self):
         dataset = Config.CLIENT.dataset(DATASET_NAME)
         self.assertFalse(dataset.exists())
-        dataset.create()
+
+        # We need to wait to stay within the rate limits.
+        # The alternative outcome is a 403 Forbidden response from upstream.
+        # See: https://cloud.google.com/bigquery/quota-policy
+        @Retry(Forbidden, tries=2, delay=30)
+        def create_dataset():
+            dataset.create()
+
+        create_dataset()
         self.to_delete.append(dataset)
         TABLE_NAME = 'test_table'
         full_name = bigquery.SchemaField('full_name', 'STRING',

system_tests/retry.py

@@ -0,0 +1,55 @@
+import time
+from functools import wraps
+
+import six
+
+
+class Retry(object):
+    """Retry class for retrying eventually consistent resources in testing."""
+
+    def __init__(self, exception, tries=4, delay=3, backoff=2, logger=None):
+        """Retry calling the decorated function using an exponential backoff.
+
+        :type exception: Exception or tuple of Exceptions
+        :param exception: The exception to check or may be a tuple of
+                          exceptions to check.
+
+        :type tries: int
+        :param tries: Number of times to try (not retry) before giving up.
+
+        :type delay: int
+        :param delay: Initial delay between retries in seconds.
+
+        :type backoff: int
+        :param backoff: Backoff multiplier e.g. value of 2 will double the
+                        delay each retry.
+
+        :type logger: logging.Logger instance
+        :param logger: Logger to use. If None, print.
+        """
+
+        self.exception = exception
+        self.tries = tries
+        self.delay = delay
+        self.backoff = backoff
+        self.logger = logger.warning if logger else six.print_
+
+    def __call__(self, to_wrap):
+        @wraps(to_wrap)
+        def wrapped_function(*args, **kwargs):
+            tries_counter = self.tries
+            delay = self.delay
+            while tries_counter > 0:
+                try:
+                    return to_wrap(*args, **kwargs)
+                except self.exception as caught_exception:
+                    msg = ("%s, Trying again in %d seconds..." %
+                           (str(caught_exception), delay))
+                    self.logger(msg)
+
+                    time.sleep(delay)
+                    tries_counter -= 1
+                    delay *= self.backoff
+            return to_wrap(*args, **kwargs)
+
+        return wrapped_function