gh-89850: Add default C implementations of persistent_id() and persistent_load() (GH-113579)

Previously the C implementation of pickle.Pickler and pickle.Unpickler
classes did not have such methods and they could only be used if
they were overloaded in subclasses or set as instance attributes.

Fixed calling super().persistent_id() and super().persistent_load() in
subclasses of the C implementation of pickle.Pickler and pickle.Unpickler
classes. It no longer causes an infinite recursion.

Author: serhiy-storchaka

Doc/library/pickle.rst

@@ -345,6 +345,10 @@ The :mod:`pickle` module exports three classes, :class:`Pickler`,
 
       See :ref:`pickle-persistent` for details and examples of uses.
 
+      .. versionchanged:: 3.13
+         Add the default implementation of this method in the C implementation
+         of :class:`!Pickler`.
+
    .. attribute:: dispatch_table
 
       A pickler object's dispatch table is a registry of *reduction
@@ -446,6 +450,10 @@ The :mod:`pickle` module exports three classes, :class:`Pickler`,
 
       See :ref:`pickle-persistent` for details and examples of uses.
 
+      .. versionchanged:: 3.13
+         Add the default implementation of this method in the C implementation
+         of :class:`!Unpickler`.
+
    .. method:: find_class(module, name)
 
       Import *module* if necessary and return the object called *name* from it,

Lib/test/test_pickle.py

@@ -122,6 +122,7 @@ class PyIdPersPicklerTests(AbstractIdentityPersistentPicklerTests,
 
     pickler = pickle._Pickler
     unpickler = pickle._Unpickler
+    persistent_load_error = pickle.UnpicklingError
 
     @support.cpython_only
     def test_pickler_reference_cycle(self):
@@ -176,7 +177,6 @@ class DispatchTable:
         support.gc_collect()
         self.assertIsNone(table_ref())
 
-
     @support.cpython_only
     def test_unpickler_reference_cycle(self):
         def check(Unpickler):
@@ -206,6 +206,28 @@ def persistent_load(pid):
                 return pid
         check(PersUnpickler)
 
+    def test_pickler_super(self):
+        class PersPickler(self.pickler):
+            def persistent_id(subself, obj):
+                self.assertIsNone(super().persistent_id(obj))
+                return obj
+
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            f = io.BytesIO()
+            pickler = PersPickler(f, proto)
+            pickler.dump('abc')
+            self.assertEqual(self.loads(f.getvalue()), 'abc')
+
+    def test_unpickler_super(self):
+        class PersUnpickler(self.unpickler):
+            def persistent_load(subself, pid):
+                with self.assertRaises(self.persistent_load_error):
+                    super().persistent_load(pid)
+                return pid
+
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            unpickler = PersUnpickler(io.BytesIO(self.dumps('abc', proto)))
+            self.assertEqual(unpickler.load(), 'abc')
 
 class PyPicklerUnpicklerObjectTests(AbstractPicklerUnpicklerObjectTests, unittest.TestCase):
 
@@ -256,6 +278,7 @@ class CPersPicklerTests(PyPersPicklerTests):
     class CIdPersPicklerTests(PyIdPersPicklerTests):
         pickler = _pickle.Pickler
         unpickler = _pickle.Unpickler
+        persistent_load_error = _pickle.UnpicklingError
 
     class CDumpPickle_LoadPickle(PyPicklerTests):
         pickler = _pickle.Pickler
@@ -326,7 +349,7 @@ class SizeofTests(unittest.TestCase):
         check_sizeof = support.check_sizeof
 
         def test_pickler(self):
-            basesize = support.calcobjsize('7P2n3i2n3i2P')
+            basesize = support.calcobjsize('6P2n3i2n3i2P')
             p = _pickle.Pickler(io.BytesIO())
             self.assertEqual(object.__sizeof__(p), basesize)
             MT_size = struct.calcsize('3nP0n')
@@ -343,7 +366,7 @@ def test_pickler(self):
                 0)  # Write buffer is cleared after every dump().
 
         def test_unpickler(self):
-            basesize = support.calcobjsize('2P2n2P 2P2n2i5P 2P3n8P2n2i')
+            basesize = support.calcobjsize('2P2nP 2P2n2i5P 2P3n8P2n2i')
             unpickler = _pickle.Unpickler
             P = struct.calcsize('P')  # Size of memo table entry.
             n = struct.calcsize('n')  # Size of mark table entry.

Misc/NEWS.d/next/Library/2023-12-29-22-29-34.gh-issue-89850.KnxiZA.rst

@@ -0,0 +1,5 @@
+Add default implementations of :meth:`pickle.Pickler.persistent_id` and
+:meth:`pickle.Unpickler.persistent_load` methods in the C implementation.
+Calling ``super().persistent_id()`` and ``super().persistent_load()`` in
+subclasses of the C implementation of :class:`pickle.Pickler` and
+:class:`pickle.Unpickler` classes no longer causes infinite recursion.