fix: Stop FeatureStoreClientWrapper poller on close (#397)

Author: jsonbailey

ldclient/impl/datasystem/fdv2.py

@@ -130,6 +130,7 @@ def __init__(self, store: FeatureStore, store_update_sink: DataStoreStatusProvid
         self.__lock = ReadWriteLock()
         self.__last_available = True
         self.__poller: Optional[RepeatingTask] = None
+        self.__closed = False
 
     def init(self, all_data: Mapping[VersionedDataKind, Mapping[str, Dict[Any, Any]]]):
         return self.__wrapper(lambda: self.store.init(_FeatureStoreDataSetSorter.sort_all_collections(all_data)))
@@ -164,6 +165,8 @@ def __update_availability(self, available: bool):
         task_to_start = None
 
         with self.__lock.write():
+            if self.__closed:
+                return
             if available == self.__last_available:
                 return
 
@@ -229,6 +232,26 @@ def is_monitoring_enabled(self) -> bool:
 
         return monitoring_enabled()
 
+    def close(self):
+        """
+        Close the wrapper and stop the repeating task poller if it's running.
+        Also forwards the close call to the underlying store if it has a close method.
+        """
+        poller_to_stop = None
+
+        with self.__lock.write():
+            if self.__closed:
+                return
+            self.__closed = True
+            poller_to_stop = self.__poller
+            self.__poller = None
+
+        if poller_to_stop is not None:
+            poller_to_stop.stop()
+
+        if hasattr(self.store, "close"):
+            self.store.close()
+
 
 class FDv2(DataSystem):
     """

ldclient/interfaces.py

@@ -189,6 +189,28 @@ def initialized(self) -> bool:
     #     :return: true if the underlying data store is reachable
     #     """
 
+    # WARN: This isn't a required method on a FeatureStore. The SDK will
+    # check if the provided store responds to this method, and if it does,
+    # will call it during shutdown to release any resources (such as database
+    # connections or connection pools) that the store may be using.
+    #
+    # @abstractmethod
+    # def close(self):
+    #     """
+    #     Releases any resources used by the data store implementation.
+    #
+    #     This method will be called by the SDK during shutdown to ensure proper
+    #     cleanup of resources such as database connections, connection pools,
+    #     network sockets, or other resources that should be explicitly released.
+    #
+    #     Implementations should be idempotent - calling close() multiple times
+    #     should be safe and have no additional effect after the first call.
+    #
+    #     This is particularly important for persistent data stores that maintain
+    #     connection pools or other long-lived resources that should be properly
+    #     cleaned up when the SDK is shut down.
+    #     """
+
 
 class FeatureStoreCore:
     """