[FBcode->GH] Support opt mode for torchvision ops (#4080)

torchvision/_register_extension.py

+import os
+import importlib.machinery
+
+
+def _get_extension_path(lib_name):
+
+    lib_dir = os.path.dirname(__file__)
+    if os.name == 'nt':
+        # Register the main torchvision library location on the default DLL path
+        import ctypes
+        import sys
+
+        kernel32 = ctypes.WinDLL('kernel32.dll', use_last_error=True)
+        with_load_library_flags = hasattr(kernel32, 'AddDllDirectory')
+        prev_error_mode = kernel32.SetErrorMode(0x0001)
+
+        if with_load_library_flags:
+            kernel32.AddDllDirectory.restype = ctypes.c_void_p
+
+        if sys.version_info >= (3, 8):
+            os.add_dll_directory(lib_dir)
+        elif with_load_library_flags:
+            res = kernel32.AddDllDirectory(lib_dir)
+            if res is None:
+                err = ctypes.WinError(ctypes.get_last_error())
+                err.strerror += f' Error adding "{lib_dir}" to the DLL directories.'
+                raise err
+
+        kernel32.SetErrorMode(prev_error_mode)
+
+    loader_details = (
+        importlib.machinery.ExtensionFileLoader,
+        importlib.machinery.EXTENSION_SUFFIXES
+    )
+
+    extfinder = importlib.machinery.FileFinder(lib_dir, loader_details)
+    ext_specs = extfinder.find_spec(lib_name)
+    if ext_specs is None:
+        raise ImportError
+
+    return ext_specs.origin

torchvision/extension.py

-_HAS_OPS = False
-
-
-def _has_ops():
-    return False
-
-
-def _register_extensions():
-    import os
-    import importlib
-    import torch
-
-    # load the custom_op_library and register the custom ops
-    lib_dir = os.path.dirname(__file__)
-    if os.name == 'nt':
-        # Register the main torchvision library location on the default DLL path
-        import ctypes
-        import sys
+import torch
 
-        kernel32 = ctypes.WinDLL('kernel32.dll', use_last_error=True)
-        with_load_library_flags = hasattr(kernel32, 'AddDllDirectory')
-        prev_error_mode = kernel32.SetErrorMode(0x0001)
+from ._register_extension import _get_extension_path
 
-        if with_load_library_flags:
-            kernel32.AddDllDirectory.restype = ctypes.c_void_p
 
-        if sys.version_info >= (3, 8):
-            os.add_dll_directory(lib_dir)
-        elif with_load_library_flags:
-            res = kernel32.AddDllDirectory(lib_dir)
-            if res is None:
-                err = ctypes.WinError(ctypes.get_last_error())
-                err.strerror += f' Error adding "{lib_dir}" to the DLL directories.'
-                raise err
+_HAS_OPS = False
 
-        kernel32.SetErrorMode(prev_error_mode)
 
-    loader_details = (
-        importlib.machinery.ExtensionFileLoader,
-        importlib.machinery.EXTENSION_SUFFIXES
-    )
-
-    extfinder = importlib.machinery.FileFinder(lib_dir, loader_details)
-    ext_specs = extfinder.find_spec("_C")
-    if ext_specs is None:
-        raise ImportError
-    torch.ops.load_library(ext_specs.origin)
+def _has_ops():
+    return False
 
 
 try:
-    _register_extensions()
+    lib_path = _get_extension_path('_C')
+    torch.ops.load_library(lib_path)
     _HAS_OPS = True
 
     def _has_ops():  # noqa: F811

torchvision/io/_video_opt.py

 
-import importlib
 import math
 import os
 import warnings
@@ -9,47 +8,15 @@ from typing import List, Tuple
 import numpy as np
 import torch
 
+from .._register_extension import _get_extension_path
 
-_HAS_VIDEO_OPT = False
 
 try:
-    lib_dir = os.path.abspath(os.path.join(os.path.dirname(__file__), ".."))
-
-    loader_details = (
-        importlib.machinery.ExtensionFileLoader,
-        importlib.machinery.EXTENSION_SUFFIXES
-    )
-
-    extfinder = importlib.machinery.FileFinder(lib_dir, loader_details)
-    ext_specs = extfinder.find_spec("video_reader")
-
-    if os.name == 'nt':
-        # Load the video_reader extension using LoadLibraryExW
-        import ctypes
-
-        kernel32 = ctypes.WinDLL('kernel32.dll', use_last_error=True)
-        with_load_library_flags = hasattr(kernel32, 'AddDllDirectory')
-        prev_error_mode = kernel32.SetErrorMode(0x0001)
-
-        if with_load_library_flags:
-            kernel32.LoadLibraryExW.restype = ctypes.c_void_p
-
-        if ext_specs is not None:
-            res = kernel32.LoadLibraryExW(ext_specs.origin, None, 0x00001100)
-            if res is None:
-                err = ctypes.WinError(ctypes.get_last_error())
-                err.strerror += (f' Error loading "{ext_specs.origin}" or any or '
-                                 'its dependencies.')
-                raise err
-
-        kernel32.SetErrorMode(prev_error_mode)
-
-    if ext_specs is not None:
-        torch.ops.load_library(ext_specs.origin)
+    lib_path = _get_extension_path('video_reader')
+    torch.ops.load_library(lib_path)
     _HAS_VIDEO_OPT = True
 except (ImportError, OSError):
-    pass
-
+    _HAS_VIDEO_OPT = False
 
 default_timebase = Fraction(0, 1)
 

torchvision/io/image.py

 import torch
-
-import os
-import os.path as osp
-import importlib.machinery
-
 from enum import Enum
 
-_HAS_IMAGE_OPT = False
-
-try:
-    lib_dir = osp.abspath(osp.join(osp.dirname(__file__), ".."))
-
-    loader_details = (
-        importlib.machinery.ExtensionFileLoader,
-        importlib.machinery.EXTENSION_SUFFIXES
-    )
-
-    extfinder = importlib.machinery.FileFinder(lib_dir, loader_details)  # type: ignore[arg-type]
-    ext_specs = extfinder.find_spec("image")
+from .._register_extension import _get_extension_path
 
-    if os.name == 'nt':
-        # Load the image extension using LoadLibraryExW
-        import ctypes
 
-        kernel32 = ctypes.WinDLL('kernel32.dll', use_last_error=True)
-        with_load_library_flags = hasattr(kernel32, 'AddDllDirectory')
-        prev_error_mode = kernel32.SetErrorMode(0x0001)
-
-        kernel32.LoadLibraryW.restype = ctypes.c_void_p
-        if with_load_library_flags:
-            kernel32.LoadLibraryExW.restype = ctypes.c_void_p
-
-        if ext_specs is not None:
-            res = kernel32.LoadLibraryExW(ext_specs.origin, None, 0x00001100)
-            if res is None:
-                err = ctypes.WinError(ctypes.get_last_error())
-                err.strerror += (f' Error loading "{ext_specs.origin}" or any or '
-                                 'its dependencies.')
-                raise err
-
-        kernel32.SetErrorMode(prev_error_mode)
-
-    if ext_specs is not None:
-        torch.ops.load_library(ext_specs.origin)
-        _HAS_IMAGE_OPT = True
+try:
+    lib_path = _get_extension_path('image')
+    torch.ops.load_library(lib_path)
 except (ImportError, OSError):
     pass