[Refactor] Simplify FutureWrapper in MultiprocExecutor (#38644)

Signed-off-by: Yifan <yzong@redhat.com>
Signed-off-by: Yifan Zong <yzong@redhat.com>

vllm/v1/executor/multiproc_executor.py

@@ -67,25 +67,29 @@ logger = init_logger(__name__)
 class FutureWrapper(Future):
     def __init__(
         self,
-        futures_queue: deque[tuple["FutureWrapper", Callable]],
+        futures_queue: deque["FutureWrapper"],
+        get_response: Callable[[], Any],
         aggregate: Callable = lambda x: x,
     ):
         self.futures_queue = futures_queue
+        self.get_response = get_response
         self.aggregate = aggregate
         super().__init__()
+        self.futures_queue.appendleft(self)
 
     def result(self, timeout=None):
         if timeout is not None:
             raise RuntimeError("timeout not implemented")
+
         # Drain any futures ahead of us in the queue.
         while not self.done():
-            future, get_response = self.futures_queue.pop()
-            future.wait_for_response(get_response)
+            future = self.futures_queue.pop()
+            future._wait_for_response()
         return super().result()
 
-    def wait_for_response(self, get_response: Callable):
+    def _wait_for_response(self):
         try:
-            response = self.aggregate(get_response())
+            response = self.aggregate(self.get_response())
             with suppress(InvalidStateError):
                 self.set_result(response)
         except Exception as e:
@@ -218,7 +222,7 @@ class MultiprocExecutor(Executor):
             for response_mq in self.response_mqs:
                 response_mq.wait_until_ready()
 
-            self.futures_queue = deque[tuple[FutureWrapper, Callable]]()
+            self.futures_queue = deque[FutureWrapper]()
 
             self._post_init_executor()
 
@@ -384,17 +388,13 @@ class MultiprocExecutor(Executor):
                 responses.append(result)
             return responses[0] if output_rank is not None else responses
 
-        if non_block:
-            future = FutureWrapper(self.futures_queue, aggregate=aggregate)
-            self.futures_queue.appendleft((future, get_response))
-            return future
+        future = FutureWrapper(
+            self.futures_queue,
+            get_response=get_response,
+            aggregate=aggregate,
+        )
 
-        # First drain any pending futures in the queue.
-        while self.futures_queue:
-            future, get_fut_response = self.futures_queue.pop()
-            future.wait_for_response(get_fut_response)
-
-        return aggregate(get_response())
+        return future if non_block else future.result()
 
     @staticmethod
     def _ensure_worker_termination(worker_procs: list[BaseProcess]):