From a3edb8b921e029e2c03d33302d408ad5d4e9d4ad Mon Sep 17 00:00:00 2001
From: Tim Swast <swast@google.com>
Date: Tue, 23 Mar 2021 15:06:24 -0500
Subject: [PATCH] fix: add ConnectionError to default retry (#571)

---
 google/cloud/bigquery/retry.py | 8 ++++----
 setup.py                       | 1 +
 testing/constraints-3.6.txt    | 1 +
 tests/unit/test_retry.py       | 9 +++++++++
 4 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/google/cloud/bigquery/retry.py b/google/cloud/bigquery/retry.py
index 4bc4b757f..20a8e7b13 100644
--- a/google/cloud/bigquery/retry.py
+++ b/google/cloud/bigquery/retry.py
@@ -14,6 +14,7 @@
 
 from google.api_core import exceptions
 from google.api_core import retry
+import requests.exceptions
 
 
 _RETRYABLE_REASONS = frozenset(
@@ -21,9 +22,11 @@
 )
 
 _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)
 
diff --git a/setup.py b/setup.py
index 99d3804ed..12a9bde31 100644
--- a/setup.py
+++ b/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": [
diff --git a/testing/constraints-3.6.txt b/testing/constraints-3.6.txt
index c4a5c51be..322373eba 100644
--- a/testing/constraints-3.6.txt
+++ b/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
diff --git a/tests/unit/test_retry.py b/tests/unit/test_retry.py
index d9f867cb3..318a54d34 100644
--- a/tests/unit/test_retry.py
+++ b/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