fix: resume read stream on Unknown transport-layer exception (#263)

Author: tswast

google/cloud/bigquery_storage_v1/reader.py

@@ -39,7 +39,12 @@
     pyarrow = None
 
 
-_STREAM_RESUMPTION_EXCEPTIONS = (google.api_core.exceptions.ServiceUnavailable,)
+_STREAM_RESUMPTION_EXCEPTIONS = (
+    google.api_core.exceptions.ServiceUnavailable,
+    # Caused by transport-level error. No status code was received.
+    # https://github.com/googleapis/python-bigquery-storage/issues/262
+    google.api_core.exceptions.Unknown,
+)
 
 # The Google API endpoint can unexpectedly close long-running HTTP/2 streams.
 # Unfortunately, this condition is surfaced to the caller as an internal error

tests/unit/test_reader_v1.py

@@ -103,6 +103,12 @@ def _pages_w_unavailable(pages):
     raise google.api_core.exceptions.ServiceUnavailable("test: please reconnect")
 
 
+def _pages_w_unknown(pages):
+    for page in pages:
+        yield page
+    raise google.api_core.exceptions.Unknown("No status received")
+
+
 def _avro_blocks_w_deadline(avro_blocks):
     for block in avro_blocks:
         yield block
@@ -237,14 +243,19 @@ def test_rows_w_reconnect(class_under_test, mock_gapic_client):
     ]
     avro_blocks_1 = _pages_w_unavailable(_bq_to_avro_blocks(bq_blocks_1, avro_schema))
     bq_blocks_2 = [[{"int_col": 1024}, {"int_col": 512}], [{"int_col": 256}]]
-    avro_blocks_2 = _bq_to_avro_blocks(bq_blocks_2, avro_schema)
     avro_blocks_2 = _pages_w_resumable_internal_error(
         _bq_to_avro_blocks(bq_blocks_2, avro_schema)
     )
-    bq_blocks_3 = [[{"int_col": 567}, {"int_col": 789}], [{"int_col": 890}]]
-    avro_blocks_3 = _bq_to_avro_blocks(bq_blocks_3, avro_schema)
-
-    mock_gapic_client.read_rows.side_effect = (avro_blocks_2, avro_blocks_3)
+    bq_blocks_3 = [[{"int_col": -1}, {"int_col": -2}], [{"int_col": -4}]]
+    avro_blocks_3 = _pages_w_unknown(_bq_to_avro_blocks(bq_blocks_3, avro_schema))
+    bq_blocks_4 = [[{"int_col": 567}, {"int_col": 789}], [{"int_col": 890}]]
+    avro_blocks_4 = _bq_to_avro_blocks(bq_blocks_4, avro_schema)
+
+    mock_gapic_client.read_rows.side_effect = (
+        avro_blocks_2,
+        avro_blocks_3,
+        avro_blocks_4,
+    )
 
     reader = class_under_test(
         avro_blocks_1,
@@ -260,16 +271,20 @@ def test_rows_w_reconnect(class_under_test, mock_gapic_client):
             itertools.chain.from_iterable(bq_blocks_1),
             itertools.chain.from_iterable(bq_blocks_2),
             itertools.chain.from_iterable(bq_blocks_3),
+            itertools.chain.from_iterable(bq_blocks_4),
         )
     )
 
     assert tuple(got) == expected
     mock_gapic_client.read_rows.assert_any_call(
         read_stream="teststream", offset=4, metadata={"test-key": "test-value"}
     )
-    mock_gapic_client.read_rows.assert_called_with(
+    mock_gapic_client.read_rows.assert_any_call(
         read_stream="teststream", offset=7, metadata={"test-key": "test-value"}
     )
+    mock_gapic_client.read_rows.assert_called_with(
+        read_stream="teststream", offset=10, metadata={"test-key": "test-value"}
+    )
 
 
 def test_rows_w_reconnect_by_page(class_under_test, mock_gapic_client):