added pre-wrapping to async client

Author: daniel-sanche

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

@@ -310,25 +310,7 @@ class {{ service.async_client_name }}:
 
         # Wrap the RPC method; this adds retry and timeout information,
         # and friendly error handling.
-        rpc = gapic_v1.method_async.wrap_method(
-            self._client._transport.{{ method.transport_safe_name|snake_case }},
-            {% if method.retry %}
-            default_retry=retries.Retry(
-                {% if method.retry.initial_backoff %}initial={{ method.retry.initial_backoff }},{% endif %}
-                {% if method.retry.max_backoff %}maximum={{ method.retry.max_backoff }},{% endif %}
-                {% if method.retry.backoff_multiplier %}multiplier={{ method.retry.backoff_multiplier }},{% endif %}
-                predicate=retries.if_exception_type(
-                    {% for ex in method.retry.retryable_exceptions|sort(attribute="__name__") %}
-                    core_exceptions.{{ ex.__name__ }},
-                    {% endfor %}
-                ),
-                deadline={{ method.timeout }},
-            ),
-            {% endif %}
-            default_timeout={{ method.timeout }},
-            client_info=DEFAULT_CLIENT_INFO,
-        )
-        {% if method.field_headers %}
+        rpc = self._client._transport._wrapped_methods[self._client._transport.{{ method.transport_safe_name|snake_case }}]
 
         # Certain fields should be provided within the metadata header;
         # add these here.

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

@@ -378,6 +378,32 @@ class {{ service.grpc_asyncio_transport_name }}({{ service.name }}Transport):
         return self._stubs["test_iam_permissions"]
     {% endif %}
 
+    def _prep_wrapped_messages(self, client_info):
+        # Precompute the wrapped methods.
+        # override base class to use async wrappers
+        self._wrapped_methods = {
+            {% for method in service.methods.values() %}
+            self.{{ method.transport_safe_name|snake_case }}: gapic_v1.method_async.wrap_method(
+                self.{{ method.transport_safe_name|snake_case }},
+                {% if method.retry %}
+                default_retry=retries.Retry(
+                    {% if method.retry.initial_backoff %}initial={{ method.retry.initial_backoff }},{% endif %}
+                    {% if method.retry.max_backoff %}maximum={{ method.retry.max_backoff }},{% endif %}
+                    {% if method.retry.backoff_multiplier %}multiplier={{ method.retry.backoff_multiplier }},{% endif %}
+                    predicate=retries.if_exception_type(
+                        {% for ex in method.retry.retryable_exceptions|sort(attribute='__name__') %}
+                        core_exceptions.{{ ex.__name__ }},
+                        {% endfor %}
+                    ),
+                    deadline={{ method.timeout }},
+                ),
+                {% endif %}
+                default_timeout={{ method.timeout }},
+                client_info=client_info,
+            ),
+            {% endfor %} {# precomputed wrappers loop #}
+        }
+
     def close(self):
         return self.grpc_channel.close()