Fix race condition during Python library loading

wrappers/python/aries_askar/bindings/lib.py

@@ -340,6 +340,7 @@ def __new__(cls, *args):
         inst = cls.INSTANCE and cls.INSTANCE()
         if inst is None:
             inst = super().__new__(cls, *args)
+            inst._initlock = threading.Lock()
             inst._lib = None
             inst._objs = []
             # Keep a weak reference to the instance. This assumes that
@@ -351,10 +352,12 @@ def __new__(cls, *args):
 
     @property
     def loaded(self) -> LibLoad:
-        """Determine if the library has been loaded."""
+        """Access the loaded library instance, initializing it if necessary."""
         if not self._lib:
-            self._lib = LibLoad(self.__class__.LIB_NAME)
-            self._objs.append(self._lib)
+            with self._initlock:
+                if not self._lib:
+                    self._lib = LibLoad(self.__class__.LIB_NAME)
+                    self._objs.append(self._lib)
         return self._lib
 
     def invoke(self, name, argtypes, *args):

wrappers/python/aries_askar/store.py

@@ -5,10 +5,9 @@
 except ImportError:
     import json
 
+from functools import lru_cache
 from typing import Optional, Sequence, Union
 
-from cached_property import cached_property
-
 from . import bindings
 from .bindings import (
     EntryListHandle,
@@ -32,22 +31,26 @@ def __init__(self, lst: EntryListHandle, pos: int):
         self._list = lst
         self._pos = pos
 
-    @cached_property
+    @property
+    @lru_cache(maxsize=None)
     def category(self) -> str:
         """Accessor for the entry category."""
         return self._list.get_category(self._pos)
 
-    @cached_property
+    @property
+    @lru_cache(maxsize=None)
     def name(self) -> str:
         """Accessor for the entry name."""
         return self._list.get_name(self._pos)
 
     @property
+    @lru_cache(maxsize=None)
     def value(self) -> bytes:
         """Accessor for the entry value."""
         return bytes(self.raw_value)
 
-    @cached_property
+    @property
+    @lru_cache(maxsize=None)
     def raw_value(self) -> memoryview:
         """Accessor for the entry raw value."""
         return self._list.get_value(self._pos)
@@ -57,7 +60,8 @@ def value_json(self) -> dict:
         """Accessor for the entry value as JSON."""
         return json.loads(self.value)
 
-    @cached_property
+    @property
+    @lru_cache(maxsize=None)
     def tags(self) -> dict:
         """Accessor for the entry tags."""
         return self._list.get_tags(self._pos)
@@ -147,27 +151,32 @@ def __init__(self, lst: KeyEntryListHandle, pos: int):
         self._list = lst
         self._pos = pos
 
-    @cached_property
+    @property
+    @lru_cache(maxsize=None)
     def algorithm(self) -> str:
         """Accessor for the key entry algorithm."""
         return self._list.get_algorithm(self._pos)
 
-    @cached_property
+    @property
+    @lru_cache(maxsize=None)
     def name(self) -> str:
         """Accessor for the key entry name."""
         return self._list.get_name(self._pos)
 
-    @cached_property
+    @property
+    @lru_cache(maxsize=None)
     def metadata(self) -> str:
         """Accessor for the key entry metadata."""
         return self._list.get_metadata(self._pos)
 
-    @cached_property
+    @property
+    @lru_cache(maxsize=None)
     def key(self) -> Key:
         """Accessor for the entry metadata."""
         return Key(self._list.load_key(self._pos))
 
-    @cached_property
+    @property
+    @lru_cache(maxsize=None)
     def tags(self) -> dict:
         """Accessor for the entry tags."""
         return self._list.get_tags(self._pos)

wrappers/python/requirements.txt

@@ -1 +0,0 @@
-cached_property~=2.0.0