fix: Prevent async deadlock on circular dependency

Author: remimd

injection/_core/common/threading.py

@@ -3,9 +3,11 @@
 from threading import RLock
 from typing import Any, ContextManager, Final
 
-_PYTHON_INJECTION_THREADSAFE: Final[bool] = bool(getenv("PYTHON_INJECTION_THREADSAFE"))
+_PYTHON_INJECTION_THREADSAFE: Final[bool] = bool(
+    int(getenv("PYTHON_INJECTION_THREADSAFE", 0))
+)
 
 
 def get_lock(threadsafe: bool | None = None) -> ContextManager[Any]:
-    cond = _PYTHON_INJECTION_THREADSAFE if threadsafe is None else threadsafe
-    return RLock() if cond else nullcontext()
+    threadsafe = _PYTHON_INJECTION_THREADSAFE if threadsafe is None else threadsafe
+    return RLock() if threadsafe else nullcontext()

injection/_core/injectables.py

@@ -1,6 +1,6 @@
 from abc import ABC, abstractmethod
-from collections.abc import Awaitable, Callable, MutableMapping
-from contextlib import suppress
+from collections.abc import Awaitable, Callable, Iterator, MutableMapping
+from contextlib import contextmanager, suppress
 from dataclasses import dataclass, field
 from functools import partial
 from typing import (
@@ -53,11 +53,13 @@ def get_instance(self) -> T:
 
 
 class CacheLogic[T]:
-    __slots__ = ("__semaphore",)
+    __slots__ = ("__is_instantiating", "__semaphore")
 
+    __is_instantiating: bool
     __semaphore: AsyncContextManager[Any]
 
     def __init__(self) -> None:
+        self.__is_instantiating = False
         self.__semaphore = AsyncSemaphore(1)
 
     async def aget_or_create[K](
@@ -66,11 +68,14 @@ async def aget_or_create[K](
         key: K,
         factory: Callable[..., Awaitable[T]],
     ) -> T:
+        self.__fail_if_instantiating()
         async with self.__semaphore:
             with suppress(KeyError):
                 return cache[key]
 
-            instance = await factory()
+            with self.__instantiating():
+                instance = await factory()
+
             cache[key] = instance
 
         return instance
@@ -81,13 +86,29 @@ def get_or_create[K](
         key: K,
         factory: Callable[..., T],
     ) -> T:
+        self.__fail_if_instantiating()
         with suppress(KeyError):
             return cache[key]
 
-        instance = factory()
+        with self.__instantiating():
+            instance = factory()
+
         cache[key] = instance
         return instance
 
+    def __fail_if_instantiating(self) -> None:
+        if self.__is_instantiating:
+            raise RecursionError("Recursive call detected during instantiation.")
+
+    @contextmanager
+    def __instantiating(self) -> Iterator[None]:
+        self.__is_instantiating = True
+
+        try:
+            yield
+        finally:
+            self.__is_instantiating = False
+
 
 @dataclass(repr=False, eq=False, frozen=True, slots=True)
 class SingletonInjectable[T](Injectable[T]):

injection/_core/locator.py

@@ -61,6 +61,7 @@ def make_injected_function[**P, T](
         self,
         wrapped: Callable[P, T],
         /,
+        threadsafe: bool | None = ...,
     ) -> Callable[P, T]:
         raise NotImplementedError
 
@@ -108,24 +109,24 @@ def request(self, provider: InjectionProvider) -> Injectable[T]:
 
         injectable = _make_injectable(
             self.factory,
-            provider.make_injected_function(self.recipe),  # type: ignore[misc]
+            provider.make_injected_function(self.recipe, threadsafe=False),  # type: ignore[misc]
         )
         self.injectables[provider] = injectable
         return injectable
 
 
 @dataclass(repr=False, eq=False, frozen=True, slots=True)
 class StaticInjectableBroker[T](InjectableBroker[T]):
-    value: Injectable[T]
+    injectable: Injectable[T]
 
     def get(self, provider: InjectionProvider) -> Injectable[T] | None:
-        return self.value
+        return self.injectable
 
     def is_locked(self, provider: InjectionProvider) -> bool:
         return False
 
     def request(self, provider: InjectionProvider) -> Injectable[T]:
-        return self.value
+        return self.injectable
 
     @classmethod
     def from_factory(

injection/_core/scope.py

@@ -191,7 +191,6 @@ def _bind_scope(
     kind: ScopeKind | ScopeKindStr,
     threadsafe: bool | None,
 ) -> Iterator[ScopeFacade]:
-    kind = ScopeKind(kind)
     lock = get_lock(threadsafe)
 
     with lock: