region: notify about enter/exit, unregion on exception

kvmd/aiotools.py

@@ -35,6 +35,7 @@ from typing import Coroutine
 from typing import AsyncGenerator
 from typing import Type
 from typing import TypeVar
+from typing import Optional
 from typing import Any
 
 import aiofiles
@@ -126,10 +127,31 @@ async def afile_write_now(afile: aiofiles.base.AiofilesContextManager, data: byt
     await run_async(os.fsync, afile.fileno())
 
 
+# =====
+class AioNotifier:
+    def __init__(self) -> None:
+        self.__queue: asyncio.queues.Queue = asyncio.Queue()
+
+    async def notify(self) -> None:
+        await self.__queue.put(None)
+
+    async def wait(self) -> None:
+        await self.__queue.get()
+        while not self.__queue.empty():
+            await self.__queue.get()
+
+
 # =====
 class AioExclusiveRegion:
-    def __init__(self, exc_type: Type[Exception]) -> None:
+    def __init__(
+        self,
+        exc_type: Type[Exception],
+        notifier: Optional[AioNotifier]=None,
+    ) -> None:
+
         self.__exc_type = exc_type
+        self.__notifier = notifier
+
         self.__busy = False
 
     def is_busy(self) -> bool:
@@ -138,11 +160,19 @@ class AioExclusiveRegion:
     async def enter(self) -> None:
         if not self.__busy:
             self.__busy = True
+            try:
+                if self.__notifier:
+                    await self.__notifier.notify()
+            except:  # noqa: E722
+                self.__busy = False
+                raise
             return
         raise self.__exc_type()
 
     async def exit(self) -> None:
         self.__busy = False
+        if self.__notifier:
+            await self.__notifier.notify()
 
     @contextlib.asynccontextmanager
     async def exit_only_on_exception(self) -> AsyncGenerator[None, None]:
@@ -162,18 +192,5 @@ class AioExclusiveRegion:
         _exc: BaseException,
         _tb: types.TracebackType,
     ) -> None:
+
         await self.exit()
-
-
-# =====
-class AioNotifier:
-    def __init__(self) -> None:
-        self.__queue: asyncio.queues.Queue = asyncio.Queue()
-
-    async def notify(self) -> None:
-        await self.__queue.put(None)
-
-    async def wait(self) -> None:
-        await self.__queue.get()
-        while not self.__queue.empty():
-            await self.__queue.get()