proper usage of asyncio.wait() for first completed

kvmd/aiotools.py

@@ -28,8 +28,11 @@ import types
 
 import typing
 
+from typing import Tuple
 from typing import List
+from typing import Set
 from typing import Callable
+from typing import Awaitable
 from typing import Coroutine
 from typing import Type
 from typing import TypeVar
@@ -86,6 +89,10 @@ async def wait_infinite() -> None:
     await asyncio.get_event_loop().create_future()
 
 
+async def wait_first(*aws: Awaitable) -> Tuple[Set[asyncio.Future], Set[asyncio.Future]]:
+    return (await asyncio.wait(list(aws), return_when=asyncio.FIRST_COMPLETED))
+
+
 # =====
 async def afile_write_now(afile: aiofiles.base.AiofilesContextManager, data: bytes) -> None:
     await afile.write(data)

kvmd/apps/kvmd/streamer.py

@@ -207,6 +207,7 @@ class Streamer:  # pylint: disable=too-many-instance-attributes
         get_logger(0).info("Installing SIGUSR2 streamer handler ...")
         asyncio.get_event_loop().add_signal_handler(signal.SIGUSR2, signal_handler)
 
+        waiter_task: Optional[asyncio.Task] = None
         prev_state: Dict = {}
         while True:
             state = await self.get_state()
@@ -214,10 +215,10 @@ class Streamer:  # pylint: disable=too-many-instance-attributes
                 yield state
                 prev_state = state
 
-            await asyncio.wait([
-                asyncio.sleep(self.__state_poll),
-                notifier.wait(),
-            ], return_when=asyncio.FIRST_COMPLETED)
+            if waiter_task is None:
+                waiter_task = asyncio.create_task(notifier.wait())
+            if waiter_task in (await aiotools.wait_first(asyncio.sleep(self.__state_poll), waiter_task))[0]:
+                waiter_task = None
 
     async def get_info(self) -> Dict:
         proc = await asyncio.create_subprocess_exec(

kvmd/plugins/msd/otg/__init__.py

@@ -206,6 +206,7 @@ class Plugin(BaseMsd):  # pylint: disable=too-many-instance-attributes
 
     async def poll_state(self) -> AsyncGenerator[Dict, None]:
         inotify_task = asyncio.create_task(self.__watch_inotify())
+        waiter_task: Optional[asyncio.Task] = None
         prev_state: Dict = {}
         try:
             while True:
@@ -219,10 +220,10 @@ class Plugin(BaseMsd):  # pylint: disable=too-many-instance-attributes
                     yield state
                     prev_state = state
 
-                await asyncio.wait([
-                    inotify_task,
-                    self.__state_notifier.wait(),
-                ], return_when=asyncio.FIRST_COMPLETED)
+                if waiter_task is None:
+                    waiter_task = asyncio.create_task(self.__state_notifier.wait())
+                if waiter_task in (await aiotools.wait_first(inotify_task, waiter_task))[0]:
+                    waiter_task = None
         finally:
             if not inotify_task.done():
                 inotify_task.cancel()