Use os.add_dll_directory on Windows

This makes DPCTLSyclInterface.dll library findable with Python 3.10

Python 3.10 modifies the behavior on how it looks for DLLs to make it
more secure. Library provides must add it to DLL search path using
'add_dll_directory' utility for Python's internal dynamic library opener
to be able to find it.

This affects loading of native extensions as well, since if native extension
depends on the DLL which can not be found by Python's library loader,
ModuleNotFoundError is raised

Author: oleksandr-pavlyk

dpctl/__init__.py

@@ -32,13 +32,17 @@
 """
 __author__ = "Intel Corp."
 
-from dpctl._sycl_context import SyclContext, SyclContextCreationError
-from dpctl._sycl_device import (
+import os
+import os.path
+
+from ._device_selection import select_device_with_aspects
+from ._sycl_context import SyclContext, SyclContextCreationError
+from ._sycl_device import (
     SyclDevice,
     SyclDeviceCreationError,
     SyclSubDeviceCreationError,
 )
-from dpctl._sycl_device_factory import (
+from ._sycl_device_factory import (
     get_devices,
     get_num_devices,
     has_accelerator_devices,
@@ -51,15 +55,15 @@
     select_gpu_device,
     select_host_device,
 )
-from dpctl._sycl_event import SyclEvent
-from dpctl._sycl_platform import SyclPlatform, get_platforms, lsplatform
-from dpctl._sycl_queue import (
+from ._sycl_event import SyclEvent
+from ._sycl_platform import SyclPlatform, get_platforms, lsplatform
+from ._sycl_queue import (
     SyclKernelInvalidRangeError,
     SyclKernelSubmitError,
     SyclQueue,
     SyclQueueCreationError,
 )
-from dpctl._sycl_queue_manager import (
+from ._sycl_queue_manager import (
     device_context,
     get_current_backend,
     get_current_device_type,
@@ -69,8 +73,6 @@
     nested_context_factories,
     set_global_queue,
 )
-
-from ._device_selection import select_device_with_aspects
 from ._sycl_timer import SyclTimer
 from ._version import get_versions
 from .enum_types import (
@@ -145,6 +147,10 @@
     "utils",
 ]
 
+if hasattr(os, "add_dll_directory"):
+    # Include folder containing DPCTLSyclInterface.dll to search path
+    os.add_dll_directory(os.path.dirname(__file__))
+
 
 def get_include():
     r"""
@@ -153,8 +159,6 @@ def get_include():
     Extension modules that need to be compiled against dpctl should use
     this function to locate the appropriate include directory.
     """
-    import os.path
-
     return os.path.join(os.path.dirname(__file__), "include")