refactor: add cache for NATS log subject calculation

faststream/nats/subscriber/usecase.py

@@ -215,10 +215,12 @@ def add_prefix(self, prefix: str) -> None:
                 for subject in (self.config.filter_subjects or ())
             ]
 
+    @cached_property
+    def _resolved_subject_string(self) -> str:
+        return self.subject or ", ".join(self.config.filter_subjects or ())
+
     def __hash__(self) -> int:
-        return self.get_routing_hash(
-            self.subject or "".join(self.config.filter_subjects or ())
-        )
+        return self.get_routing_hash(self._resolved_subject_string)
 
     @staticmethod
     def get_routing_hash(
@@ -558,7 +560,7 @@ def get_log_context(
         """Log context factory using in `self.consume` scope."""
         return self.build_log_context(
             message=message,
-            subject=self.subject or ", ".join(self.config.filter_subjects or ()),
+            subject=self._resolved_subject_string,
             queue=self.queue,
             stream=self.stream.name,
         )

tests/brokers/nats/test_consume.py

@@ -60,7 +60,6 @@ def subscriber(m):
             await br.start()
             await asyncio.wait(
                 (
-                    asyncio.create_task(br.publish(1, f"{queue}.b")),
                     asyncio.create_task(br.publish(2, f"{queue}.a")),
                     asyncio.create_task(event.wait()),
                 ),