feat: add client debug logging support for server side streaming REST calls (#2340)

Co-authored-by: Victor Chudnovsky <vchudnov@google.com>

Author: parthea

gapic/templates/%namespace/%name_%version/%sub/services/%service/transports/rest.py.j2

@@ -262,17 +262,24 @@ class {{service.name}}RestTransport(_Base{{ service.name }}RestTransport):
             resp = self._interceptor.post_{{ method.name|snake_case }}(resp)
             response_metadata = [(k, str(v)) for k, v in response.headers.items()]
             resp, _ = self._interceptor.post_{{ method.name|snake_case }}_with_metadata(resp, response_metadata)
-            {# TODO(https://github.com/googleapis/gapic-generator-python/issues/2279): Add logging support for rest streaming. #}
-            {% if not method.server_streaming %}
             if CLIENT_LOGGING_SUPPORTED and _LOGGER.isEnabledFor(logging.DEBUG):  # pragma: NO COVER
+                {# TODO(https://github.com/googleapis/gapic-generator-python/issues/2389): #}
+                {# Depending how we want to log (a) receiving a streaming response vs (b) exposing the next streamed item to the user, we could possibly want to log something here #}
+                {# (a) should always happen in api-core #}
+                {# (b) could happen in api-core, or it could happen here when we iterate to the next streamed item that was previously received. #}
+                {% if not method.server_streaming %}
                 try:
                     response_payload = {% if method.output.ident.is_proto_plus_type %}{{ method.output.ident }}.to_json(response){% else %}json_format.MessageToJson(resp){% endif %}
 
                 except:
                     {# TODO(https://github.com/googleapis/gapic-generator-python/issues/2283): Remove try/except once unit tests are updated. #}
                     response_payload = None
+                {% endif %}{# if not method.server_streaming #}
                 http_response = {
+                {# Not logging response payload for server streaming here. See comment above. #}
+                {% if not method.server_streaming %}
                 "payload": response_payload,
+                {% endif %}{# if not method.server_streaming #}
                 "headers":  dict(response.headers),
                 "status": response.status_code,
                 }
@@ -286,7 +293,6 @@ class {{service.name}}RestTransport(_Base{{ service.name }}RestTransport):
                         "httpResponse": http_response,
                     },
                 )
-            {% endif %}{# if not method.server_streaming #}
             return resp
 
             {% endif %}{# method.void #}

gapic/templates/%namespace/%name_%version/%sub/services/%service/transports/rest_asyncio.py.j2

@@ -222,17 +222,24 @@ class Async{{service.name}}RestTransport(_Base{{ service.name }}RestTransport):
             resp = await self._interceptor.post_{{ method.name|snake_case }}(resp)
             response_metadata = [(k, str(v)) for k, v in response.headers.items()]
             resp, _ = await self._interceptor.post_{{ method.name|snake_case }}_with_metadata(resp, response_metadata)
-            {# TODO(https://github.com/googleapis/gapic-generator-python/issues/2279): Add logging support for rest streaming. #}
-            {% if not method.server_streaming %}
             if CLIENT_LOGGING_SUPPORTED and _LOGGER.isEnabledFor(logging.DEBUG):  # pragma: NO COVER
+            {# TODO(https://github.com/googleapis/gapic-generator-python/issues/2389): #}
+            {# Depending how we want to log (a) receiving a streaming response vs (b) exposing the next streamed item to the user, we could possibly want to log something here #}
+            {# (a) should always happen in api-core #}
+            {# (b) could happen in api-core, or it could happen here when we iterate to the next streamed item that was previously received. #}
+            {% if not method.server_streaming %}
                 try:
                     response_payload = {% if method.output.ident.is_proto_plus_type %}{{ method.output.ident }}.to_json(response){% else %}json_format.MessageToJson(resp){% endif %}
 
                 except:
                     {# TODO(https://github.com/googleapis/gapic-generator-python/issues/2283): Remove try/except once unit tests are updated. #}
                     response_payload = None
+            {% endif %}{# if not method.server_streaming #}
                 http_response = {
+                {# Not logging response payload for server streaming here. See comment above. #}
+                {% if not method.server_streaming %}
                     "payload": response_payload,
+                {% endif %}{# if not method.server_streaming #}
                     "headers":  dict(response.headers),
                     "status": "OK", # need to obtain this properly
                 }
@@ -246,7 +253,6 @@ class Async{{service.name}}RestTransport(_Base{{ service.name }}RestTransport):
                     },
                 )
 
-            {% endif %}{# if not method.server_streaming #}
             return resp
 
             {% endif %}{# method.void #}