move inspect.signature out of subscriber loop

src/ezmsg/core/backendprocess.py

@@ -301,34 +301,27 @@ async def perf_publish(stream: Stream, obj: Any) -> None:
             )
 
         pub_fn = perf_publish if hasattr(task, TIMEIT_ATTR) else publish
+
+        call_fn = lambda _: task(unit)
+        signature = inspect.signature(task)
+        if len(signature.parameters) == 1:
+            call_fn = lambda _: task(unit)
+        elif len(signature.parameters) == 2:
+            call_fn = lambda msg: task(unit, msg)
+        else:
+            logger.error(f'Incompatible call signature on task: {task.__name__}')
 
         @wraps(task)
         async def wrapped_task(msg: Any = None) -> None:
             try:
-
-                result = None
-                signature = inspect.signature(task)
-                if len(signature.parameters) == 1:
-                    # Task does not accept incoming messages
-                    result = task(unit)
-                elif len(signature.parameters) == 2:
-                    # Task requires an incoming message
-                    if not getattr(task, ZERO_COPY_ATTR, False):
-                        msg = deepcopy(msg)
-                    result = task(unit, msg)
-                else:
-                    logger.error(f'Incompatible call signature on task: {task.__name__}')
-
+                result = call_fn(msg)
                 if inspect.isasyncgen(result):
-                    # Task returned an async generator
-                    # it must want to publish stuff
                     async for stream, obj in result:
                         if obj and getattr(task, ZERO_COPY_ATTR, False) and obj is msg:
                             obj = deepcopy(obj)
                         await pub_fn(stream, obj)
 
                 elif asyncio.iscoroutine(result):
-                    # Task returned a simple coroutine
                     await result
 
             except Complete: