Merge pull request #1 from numberly/480-fix-concurrent-cache-access

fix aio-libs#480, concurrent cache access with ttl

async_lru/__init__.py

@@ -159,9 +159,8 @@ def _task_done_callback(
     ) -> None:
         self.__tasks.remove(task)
 
-        if self.__ttl is not None:
+        if self.__ttl is not None and (cache_item := self.__cache.get(key)):
             loop = asyncio.get_running_loop()
-            cache_item = self.__cache[key]
             cache_item.later_call = loop.call_later(
                 self.__ttl, self.__cache.pop, key, None
             )

tests/test_ttl.py

@@ -58,3 +58,12 @@ async def coro(val: int) -> int:
     # cache is not cleared after ttl expires because invalidate also should clear
     # the invalidation by timeout
     check_lru(coro, hits=0, misses=2, cache=1, tasks=0, maxsize=None)
+
+
+async def test_ttl_concurrent() -> None:
+    @alru_cache(maxsize=1, ttl=1)
+    async def coro(val: int) -> int:
+        return val
+
+    results = await asyncio.gather(*[coro(i) for i in range(2)])
+    assert results == list(range(2))