fix: add ConnectionError to default retry (#571)

google/cloud/bigquery/retry.py

@@ -14,16 +14,19 @@
 
 from google.api_core import exceptions
 from google.api_core import retry
+import requests.exceptions
 
 
 _RETRYABLE_REASONS = frozenset(
     ["rateLimitExceeded", "backendError", "internalError", "badGateway"]
 )
 
 _UNSTRUCTURED_RETRYABLE_TYPES = (
+    ConnectionError,
     exceptions.TooManyRequests,
     exceptions.InternalServerError,
     exceptions.BadGateway,
+    requests.exceptions.ConnectionError,
 )
 
 
@@ -33,10 +36,7 @@ def _should_retry(exc):
     We retry if and only if the 'reason' is 'backendError'
     or 'rateLimitExceeded'.
     """
-    if not hasattr(exc, "errors"):
-        return False
-
-    if len(exc.errors) == 0:
+    if not hasattr(exc, "errors") or len(exc.errors) == 0:
         # Check for unstructured error returns, e.g. from GFE
         return isinstance(exc, _UNSTRUCTURED_RETRYABLE_TYPES)
 

setup.py

@@ -35,6 +35,7 @@
     "google-resumable-media >= 0.6.0, < 2.0dev",
     "packaging >= 14.3",
     "protobuf >= 3.12.0",
+    "requests >= 2.18.0, < 3.0.0dev",
 ]
 extras = {
     "bqstorage": [

testing/constraints-3.6.txt

@@ -17,5 +17,6 @@ pandas==0.23.0
 proto-plus==1.10.0
 protobuf==3.12.0
 pyarrow==1.0.0
+requests==2.18.0
 six==1.13.0
 tqdm==4.7.4

tests/unit/test_retry.py

@@ -15,6 +15,7 @@
 import unittest
 
 import mock
+import requests.exceptions
 
 
 class Test_should_retry(unittest.TestCase):
@@ -42,6 +43,14 @@ def test_w_rateLimitExceeded(self):
         exc = mock.Mock(errors=[{"reason": "rateLimitExceeded"}], spec=["errors"])
         self.assertTrue(self._call_fut(exc))
 
+    def test_w_unstructured_connectionerror(self):
+        exc = ConnectionError()
+        self.assertTrue(self._call_fut(exc))
+
+    def test_w_unstructured_requests_connectionerror(self):
+        exc = requests.exceptions.ConnectionError()
+        self.assertTrue(self._call_fut(exc))
+
     def test_w_unstructured_too_many_requests(self):
         from google.api_core.exceptions import TooManyRequests