[Bugfix] Prevent DiffusionResultPump crash on cancelled futures (#5793) (#5983)

Signed-off-by: ANURAG KANADE <anuragkanade6@gmail.com>

vllm_omni/diffusion/utils/future_utils.py

@@ -0,0 +1,27 @@
+"""Helpers for resolving ``concurrent.futures.Future`` objects shared across threads."""
+
+import concurrent.futures
+from typing import Any, TypeVar
+
+from vllm.logger import init_logger
+
+logger = init_logger(__name__)
+
+_ResultT = TypeVar("_ResultT")
+
+
+def try_set_result(fut: concurrent.futures.Future[_ResultT], result: _ResultT) -> None:
+    # fut may be cancelled concurrently (e.g. asyncio.wait_for timeout) between
+    # the caller's fut.done() check and this call; drop the late result instead
+    # of crashing the pump thread.
+    try:
+        fut.set_result(result)
+    except concurrent.futures.InvalidStateError:
+        logger.debug("Dropping late result for already-resolved/cancelled future")
+
+
+def try_set_exception(fut: concurrent.futures.Future[Any], exc: BaseException) -> None:
+    try:
+        fut.set_exception(exc)
+    except concurrent.futures.InvalidStateError:
+        logger.debug("Dropping late exception for already-resolved/cancelled future")