replace _ExternalRef logic with persistent_id (#365)

Co-authored-by: Alexander Guschin <[email protected]>

mlem/contrib/callable.py

@@ -1,13 +1,11 @@
-import pickle
 import posixpath
 from collections import defaultdict
 from importlib import import_module
 from io import BytesIO
-from pickle import _Unpickler  # type: ignore
 from typing import Any, Callable, ClassVar, Dict, Optional, Tuple
 from uuid import uuid4
 
-from dill import Pickler
+from dill import Pickler, Unpickler
 
 from mlem.core.artifacts import Artifacts, Storage
 from mlem.core.hooks import LOW_PRIORITY_VALUE
@@ -146,38 +144,12 @@ def __init__(self, model, *args, **kwargs):
         self.model = model
         self.refs: Dict[str, Tuple[ModelIO, Any]] = {}
 
-        # we couldn't import hook and analyzer at top as it leads to circular import failure
         known_types = set()
         for hook in ModelAnalyzer.hooks:
             if not isinstance(hook, CallableModelType) and hook.valid_types:
                 known_types.update(hook.valid_types)
         self.known_types = tuple(known_types)
 
-    # pickle "hook" for overriding serialization of objects
-    def save(self, obj, save_persistent_id=True):
-        """
-        Checks if obj has IO.
-        If it does, serializes object with `ModelIO.dump`
-        and creates a ref to it. Otherwise, saves object as default pickle would do
-        :param obj: obj to save
-        :param save_persistent_id:
-        :return:
-        """
-        if obj is self.model:
-            # at starting point, follow usual path not to fall into infinite loop
-            return super().save(obj, save_persistent_id)
-
-        io = self._get_non_pickle_io(obj)
-        if io is None:
-            # no non-Pickle IO found, follow usual path
-            return super().save(obj, save_persistent_id)
-
-        # found model with non-pickle serialization:
-        # replace with `_ExternalRef` stub and memorize IO to serialize model aside later
-        obj_uuid = str(uuid4())
-        self.refs[obj_uuid] = (io, obj)
-        return super().save(_ExternalRef(obj_uuid), save_persistent_id)
-
     def _get_non_pickle_io(self, obj):
         """
         Checks if obj has non-Pickle IO and returns it
@@ -200,49 +172,22 @@ def _get_non_pickle_io(self, obj):
             # non-model object
             return None
 
+    def persistent_id(self, obj: Any) -> Any:
+        io = self._get_non_pickle_io(obj)
+        if io is None:
+            return None
+        obj_uuid = str(uuid4())
+        self.refs[obj_uuid] = (io, obj)
+        return obj_uuid
 
-# `Unpickler`, unlike `_Unpickler`, doesn't support `load_build` overriding
-class _ModelUnpickler(_Unpickler):
-    """
-    A class to unpickle model saved with :class:`_ModelPickler`
-    :param refs: dict of object uuid -> ref_obj
-    :param args: pickle._Unpickler args
-    :param kwargs: pickle._Unpickle kwargs
-    """
-
-    dispatch = _Unpickler.dispatch.copy()
 
+class _ModelUnpickler(Unpickler):
     def __init__(self, refs, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.refs = refs
 
-    # pickle "hook" for overriding deserialization of objects
-    def load_build(self):
-        """
-        Checks if last builded object is :class:`_ExternalRef` and if it is, swaps it with referenced object
-        :return:
-        """
-        super().load_build()
-
-        # this is the last deserialized object for now
-        obj = self.stack[-1]
-        if not isinstance(obj, _ExternalRef):
-            return
-
-        # replace `_ExternalRef` with a real model it references
-        self.stack.pop()
-        self.stack.append(self.refs[obj.ref])
-
-    dispatch[pickle.BUILD[0]] = load_build  # type: ignore
-
-
-class _ExternalRef:
-    """
-    A class to mark objects dumped their own :class:`ModelIO`
-    """
-
-    def __init__(self, ref: str):
-        self.ref = ref
+    def persistent_load(self, pid: str) -> Any:
+        return self.refs[pid]
 
 
 class CallableModelType(ModelType, ModelHook):