[Fix] Fix pickle the Python style config (#1241)

mmengine/config/config.py

@@ -261,6 +261,24 @@ class ConfigDict(Dict):
         for key, value in merged.items():
             self[key] = value
 
+    def __getstate__(self):
+        state = {}
+        for key, value in super().items():
+            state[key] = value
+        return state
+
+    def __setstate__(self, state):
+        for key, value in state.items():
+            self[key] = value
+
+    def __eq__(self, other):
+        if isinstance(other, ConfigDict):
+            return other.to_dict() == self.to_dict()
+        elif isinstance(other, dict):
+            return {k: v for k, v in self.items()} == other
+        else:
+            return False
+
     def _to_lazy_dict(self):
         """Convert the ConfigDict to a normal dictionary recursively, and keep
         the ``LazyObject`` or ``LazyAttr`` object not built."""
@@ -281,8 +299,8 @@ class ConfigDict(Dict):
         return _to_dict(self)
 
     def to_dict(self):
-        """Convert the ConfigDict to a normal dictionary recursively, and keep
+        """Convert the ConfigDict to a normal dictionary recursively, and
-        the ``LazyObject`` or ``LazyAttr`` object not built."""
+        convert the ``LazyObject`` or ``LazyAttr`` to string."""
         return _lazy2string(self, dict_type=dict)
 
 
@@ -363,12 +381,14 @@ class Config:
     .. _config tutorial: https://mmengine.readthedocs.io/en/latest/advanced_tutorials/config.html
     """  # noqa: E501
 
-    def __init__(self,
+    def __init__(
+        self,
         cfg_dict: dict = None,
         cfg_text: Optional[str] = None,
         filename: Optional[Union[str, Path]] = None,
         env_variables: Optional[dict] = None,
-                 format_python_code: bool = True):
+        format_python_code: bool = True,
+    ):
         filename = str(filename) if isinstance(filename, Path) else filename
         if cfg_dict is None:
             cfg_dict = dict()
@@ -384,6 +404,9 @@ class Config:
         super().__setattr__('_cfg_dict', cfg_dict)
         super().__setattr__('_filename', filename)
         super().__setattr__('_format_python_code', format_python_code)
+        if not hasattr(self, '_imported_names'):
+            super().__setattr__('_imported_names', set())
+
         if cfg_text:
             text = cfg_text
         elif filename:
@@ -445,7 +468,8 @@ class Config:
                 cfg_dict,
                 cfg_text=cfg_text,
                 filename=filename,
-                env_variables=env_variables)
+                env_variables=env_variables,
+            )
         else:
             # Enable lazy import when parsing the config.
             # Using try-except to make sure ``ConfigDict.lazy`` will be reset
@@ -457,15 +481,10 @@ class Config:
             except Exception as e:
                 raise e
             finally:
+                # disable lazy import to get the real type. See more details
+                # about lazy in the docstring of ConfigDict
                 ConfigDict.lazy = False
 
-            # delete builtin imported objects
-            for key, value in list(cfg_dict._to_lazy_dict().items()):
-                if isinstance(value, (types.FunctionType, types.ModuleType)):
-                    cfg_dict.pop(key)
-
-            # disable lazy import to get the real type. See more details about
-            # lazy in the docstring of ConfigDict
             cfg = Config(
                 cfg_dict,
                 filename=filename,
@@ -996,7 +1015,7 @@ class Config:
         #    accessed, but will not be dumped by default.
 
         with open(filename, encoding='utf-8') as f:
-            global_dict = {'LazyObject': LazyObject}
+            global_dict = {'LazyObject': LazyObject, '__file__': filename}
             base_dict = {}
 
             parsed_codes = ast.parse(f.read())
@@ -1470,9 +1489,13 @@ class Config:
     def __iter__(self):
         return iter(self._cfg_dict)
 
-    def __getstate__(self) -> Tuple[dict, Optional[str], Optional[str], dict]:
+    def __getstate__(
-        return (self._cfg_dict, self._filename, self._text,
+            self
-                self._env_variables)
+    ) -> Tuple[dict, Optional[str], Optional[str], dict, bool, set]:
+        state = (self._cfg_dict, self._filename, self._text,
+                 self._env_variables, self._format_python_code,
+                 self._imported_names)
+        return state
 
     def __deepcopy__(self, memo):
         cls = self.__class__
@@ -1495,12 +1518,13 @@ class Config:
     copy = __copy__
 
     def __setstate__(self, state: Tuple[dict, Optional[str], Optional[str],
-                                        dict]):
+                                        dict, bool, set]):
-        _cfg_dict, _filename, _text, _env_variables = state
+        super().__setattr__('_cfg_dict', state[0])
-        super().__setattr__('_cfg_dict', _cfg_dict)
+        super().__setattr__('_filename', state[1])
-        super().__setattr__('_filename', _filename)
+        super().__setattr__('_text', state[2])
-        super().__setattr__('_text', _text)
+        super().__setattr__('_env_variables', state[3])
-        super().__setattr__('_text', _env_variables)
+        super().__setattr__('_format_python_code', state[4])
+        super().__setattr__('_imported_names', state[5])
 
     def dump(self, file: Optional[Union[str, Path]] = None):
         """Dump config to file or return config text.
@@ -1616,8 +1640,8 @@ class Config:
         return False
 
     def _to_lazy_dict(self, keep_imported: bool = False) -> dict:
-        """Convert config object to dictionary and filter the imported
+        """Convert config object to dictionary with lazy object, and filter the
-        object."""
+        imported object."""
         res = self._cfg_dict._to_lazy_dict()
         if hasattr(self, '_imported_names') and not keep_imported:
             res = {
@@ -1637,7 +1661,14 @@ class Config:
         If you import third-party objects in the config file, all imported
         objects will be converted to a string like ``torch.optim.SGD``
         """
-        return self._cfg_dict.to_dict()
+        cfg_dict = self._cfg_dict.to_dict()
+        if hasattr(self, '_imported_names') and not keep_imported:
+            cfg_dict = {
+                key: value
+                for key, value in cfg_dict.items()
+                if key not in self._imported_names
+            }
+        return cfg_dict
 
 
 class DictAction(Action):

mmengine/config/lazy.py

@@ -121,6 +121,16 @@ class LazyObject:
 
     __repr__ = __str__
 
+    # `pickle.dump` will try to get the `__getstate__` and `__setstate__`
+    # methods of the dumped object. If these two methods are not defined,
+    # LazyObject will return a `__getstate__` LazyObject` or `__setstate__`
+    # LazyObject.
+    def __getstate__(self):
+        return self.__dict__
+
+    def __setstate__(self, state):
+        self.__dict__ = state
+
 
 class LazyAttr:
     """The attribute of the LazyObject.
@@ -219,3 +229,13 @@ class LazyAttr:
         return self.name
 
     __repr__ = __str__
+
+    # `pickle.dump` will try to get the `__getstate__` and `__setstate__`
+    # methods of the dumped object. If these two methods are not defined,
+    # LazyAttr will return a `__getstate__` LazyAttr` or `__setstate__`
+    # LazyAttr.
+    def __getstate__(self):
+        return self.__dict__
+
+    def __setstate__(self, state):
+        self.__dict__ = state

mmengine/config/utils.py

@@ -165,6 +165,8 @@ def _is_builtin_module(module_name: str) -> bool:
         return False
     if module_name.startswith('mmengine.config'):
         return True
+    if module_name in sys.builtin_module_names:
+        return True
     spec = find_spec(module_name.split('.')[0])
     # Module not found
     if spec is None:
@@ -314,6 +316,15 @@ class ImportTransformer(ast.NodeTransformer):
         # Built-in modules will not be parsed as LazyObject
         module = f'{node.level*"."}{node.module}'
         if _is_builtin_module(module):
+            # Make sure builtin module will be added into `self.imported_obj`
+            for alias in node.names:
+                if alias.asname is not None:
+                    self.imported_obj.add(alias.asname)
+                elif alias.name == '*':
+                    raise ConfigParsingError(
+                        'Cannot import * from non-base config')
+                else:
+                    self.imported_obj.add(alias.name)
             return node
 
         if module in self.base_dict:
@@ -409,6 +420,8 @@ class ImportTransformer(ast.NodeTransformer):
         alias = alias_list[0]
         if alias.asname is not None:
             self.imported_obj.add(alias.asname)
+            if _is_builtin_module(alias.name.split('.')[0]):
+                return node
             return ast.parse(  # type: ignore
                 f'{alias.asname} = LazyObject('
                 f'"{alias.name}",'

tests/data/config/lazy_module_config/test_mix_builtin.py

@@ -0,0 +1,16 @@
+# Copyright (c) OpenMMLab. All rights reserved.
+import os.path as osp
+from functools import partial
+from itertools import chain
+from os.path import basename
+from os.path import exists as ex
+from os.path import splitext
+
+import numpy as np
+
+path = osp.join('a', 'b')
+name, suffix = splitext('a/b.py')
+chained = list(chain([1, 2], [3, 4]))
+existed = ex(__file__)
+cfgname = partial(basename, __file__)()
+

tests/test_config/test_config.py

@@ -3,6 +3,7 @@ import argparse
 import copy
 import os
 import os.path as osp
+import pickle
 import platform
 import sys
 import tempfile
@@ -951,6 +952,19 @@ class TestConfig:
         assert isinstance(model.roi_head.bbox_head.loss_cls, ToyLoss)
         DefaultScope._instance_dict.pop('test1')
 
+    def test_pickle(self):
+        # Text style config
+        cfg_path = osp.join(self.data_path, 'config/py_config/test_py_base.py')
+        cfg = Config.fromfile(cfg_path)
+        pickled = pickle.loads(pickle.dumps(cfg))
+        assert pickled.__dict__ == cfg.__dict__
+
+        cfg_path = osp.join(self.data_path,
+                            'config/lazy_module_config/toy_model.py')
+        cfg = Config.fromfile(cfg_path)
+        pickled = pickle.loads(pickle.dumps(cfg))
+        assert pickled.__dict__ == cfg.__dict__
+
     def test_lazy_import(self, tmp_path):
         lazy_import_cfg_path = osp.join(
             self.data_path, 'config/lazy_module_config/toy_model.py')
@@ -1036,6 +1050,26 @@ error_attr = mmengine.error_attr
                 osp.join(self.data_path,
                          'config/lazy_module_config/error_mix_using2.py'))
 
+        cfg = Config.fromfile(
+            osp.join(self.data_path,
+                     'config/lazy_module_config/test_mix_builtin.py'))
+        assert cfg.path == osp.join('a', 'b')
+        assert cfg.name == 'a/b'
+        assert cfg.suffix == '.py'
+        assert cfg.chained == [1, 2, 3, 4]
+        assert cfg.existed
+        assert cfg.cfgname == 'test_mix_builtin.py'
+
+        cfg_dict = cfg.to_dict()
+        dumped_cfg_path = tmp_path / 'test_dump_lazy.py'
+        cfg.dump(dumped_cfg_path)
+        dumped_cfg = Config.fromfile(dumped_cfg_path)
+
+        assert set(dumped_cfg.keys()) == {
+            'path', 'name', 'suffix', 'chained', 'existed', 'cfgname'
+        }
+        assert dumped_cfg.to_dict() == cfg.to_dict()
+
 
 class TestConfigDict(TestCase):