Playing with retries.

Author: daspecster

system_tests/bigquery.py

@@ -21,6 +21,7 @@
 from gcloud.environment_vars import TESTS_PROJECT
 from gcloud import bigquery
 
+from retry import retry
 from system_test_utils import unique_resource_id
 
 
@@ -81,6 +82,7 @@ def test_patch_dataset(self):
         self.assertEqual(dataset.friendly_name, 'Friendly')
         self.assertEqual(dataset.description, 'Description')
 
+    @retry(Exception, tries=3, delay=30)
     def test_update_dataset(self):
         dataset = Config.CLIENT.dataset(DATASET_NAME)
         self.assertFalse(dataset.exists())
@@ -185,6 +187,7 @@ def test_patch_table(self):
         self.assertEqual(table.friendly_name, 'Friendly')
         self.assertEqual(table.description, 'Description')
 
+    @retry(Exception, tries=3, delay=20)
     def test_update_table(self):
         dataset = Config.CLIENT.dataset(DATASET_NAME)
         self.assertFalse(dataset.exists())

system_tests/retry.py

@@ -0,0 +1,45 @@
+import time
+from functools import wraps
+
+
+def retry(ExceptionToCheck, tries=4, delay=3, backoff=2, logger=None):
+    """Retry calling the decorated function using an exponential backoff.
+
+    http://www.saltycrane.com/blog/2009/11/trying-out-retry-decorator-python/
+    original from: http://wiki.python.org/moin/PythonDecoratorLibrary#Retry
+
+    :param ExceptionToCheck: the exception to check. may be a tuple of
+        exceptions to check
+    :type ExceptionToCheck: Exception or tuple
+    :param tries: number of times to try (not retry) before giving up
+    :type tries: int
+    :param delay: initial delay between retries in seconds
+    :type delay: int
+    :param backoff: backoff multiplier e.g. value of 2 will double the delay
+        each retry
+    :type backoff: int
+    :param logger: logger to use. If None, print
+    :type logger: logging.Logger instance
+    """
+    def deco_retry(f):
+
+        @wraps(f)
+        def f_retry(*args, **kwargs):
+            mtries, mdelay = tries, delay
+            while mtries > 1:
+                try:
+                    return f(*args, **kwargs)
+                except ExceptionToCheck as e:
+                    msg = "%s, Retrying in %d seconds..." % (str(e), mdelay)
+                    if logger:
+                        logger.warning(msg)
+                    else:
+                        print(msg)
+                    time.sleep(mdelay)
+                    mtries -= 1
+                    mdelay *= backoff
+            return f(*args, **kwargs)
+
+        return f_retry  # true decorator
+
+    return deco_retry