Rework async resources callbacks to .add_done_callback() style (fixes pypy3 issue)

src/dependency_injector/providers.pyx

@@ -3,6 +3,7 @@
 from __future__ import absolute_import
 
 import copy
+import functools
 import inspect
 import os
 import re
@@ -2719,7 +2720,7 @@ cdef class Resource(Provider):
                 pass
             else:
                 if inspect.isawaitable(shutdown):
-                    return __async_resource_shutdown(self, shutdown)
+                    return self._create_shutdown_future(shutdown)
 
         self.__resource = None
         self.__initialized = False
@@ -2764,7 +2765,7 @@ cdef class Resource(Provider):
             )
             self.__initialized = True
             self.__async = True
-            return __async_resource_init(self, async_init, initializer.shutdown)
+            return self._create_init_future(async_init, initializer.shutdown)
         elif inspect.isgeneratorfunction(self.__initializer):
             initializer = __call(
                 self.__initializer,
@@ -2789,7 +2790,7 @@ cdef class Resource(Provider):
             )
             self.__initialized = True
             self.__async = True
-            return __async_resource_init(self, initializer)
+            return self._create_init_future(initializer)
         elif isasyncgenfunction(self.__initializer):
             initializer = __call(
                 self.__initializer,
@@ -2802,7 +2803,7 @@ cdef class Resource(Provider):
             )
             self.__initialized = True
             self.__async = True
-            return __async_resource_init(self, initializer.__anext__(), initializer.asend)
+            return self._create_init_future(initializer.__anext__(), initializer.asend)
         elif callable(self.__initializer):
             self.__resource = __call(
                 self.__initializer,
@@ -2819,6 +2820,43 @@ cdef class Resource(Provider):
         self.__initialized = True
         return self.__resource
 
+    def _create_init_future(self, future, shutdowner=None):
+        callback = self._async_init_callback
+        if shutdowner:
+            callback = functools.partial(callback, shutdowner=shutdowner)
+
+        future = asyncio.ensure_future(future)
+        future.add_done_callback(callback)
+        return future
+
+    def _async_init_callback(self, initializer, shutdowner=None):
+        try:
+            resource = initializer.result()
+        except Exception:
+            self.__initialized = False
+            raise
+        else:
+            self.__resource = resource
+            self.__shutdowner = shutdowner
+
+    def _create_shutdown_future(self, shutdown_future):
+        future = asyncio.Future()
+        shutdown_future = asyncio.ensure_future(shutdown_future)
+        shutdown_future.add_done_callback(functools.partial(self._async_shutdown_callback, future))
+        return future
+
+    def _async_shutdown_callback(self, future_result, shutdowner):
+        try:
+            shutdowner.result()
+        except StopAsyncIteration:
+            pass
+
+        self.__resource = None
+        self.__initialized = False
+        self.__shutdowner = None
+
+        future_result.set_result(None)
+
     @staticmethod
     def _is_resource_subclass(instance):
         if  sys.version_info < (3, 5):
@@ -3468,26 +3506,3 @@ def isasyncgenfunction(obj):
         return inspect.isasyncgenfunction(obj)
     except AttributeError:
         return False
-
-
-async def __async_resource_init(self: Resource, initializer: object, shutdowner: object = None) -> None:
-    try:
-        resource = await initializer
-    except Exception:
-        self.__initialized = False
-        raise
-    else:
-        self.__resource = resource
-        self.__shutdowner = shutdowner
-        return self.__resource
-
-
-async def __async_resource_shutdown(self: Resource, shutdowner: object) -> None:
-    try:
-        await shutdowner
-    except StopAsyncIteration:
-        pass
-
-    self.__resource = None
-    self.__initialized = False
-    self.__shutdowner = None