From 60f7a43e94db9209e0e696dcde39f15b0e078bd7 Mon Sep 17 00:00:00 2001
From: Ashwin Srinath <shwina@users.noreply.github.com>
Date: Fri, 11 Feb 2022 13:33:42 -0500
Subject: [PATCH 1/3] Replace custom `cached_property` implementation with
 functools

---
 python/cudf/cudf/core/_base_index.py     |  2 +-
 python/cudf/cudf/core/column_accessor.py |  7 +++----
 python/cudf/cudf/core/frame.py           |  4 ++--
 python/cudf/cudf/core/groupby/groupby.py |  3 ++-
 python/cudf/cudf/core/index.py           |  3 ++-
 python/cudf/cudf/core/indexed_frame.py   |  2 +-
 python/cudf/cudf/core/join/join.py       |  4 ++--
 python/cudf/cudf/core/multiindex.py      |  7 ++-----
 python/cudf/cudf/utils/utils.py          | 22 ----------------------
 9 files changed, 15 insertions(+), 39 deletions(-)

diff --git a/python/cudf/cudf/core/_base_index.py b/python/cudf/cudf/core/_base_index.py
index 2e6f138d2e3..1d8d04e897b 100644
--- a/python/cudf/cudf/core/_base_index.py
+++ b/python/cudf/cudf/core/_base_index.py
@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import pickle
+from functools import cached_property
 from typing import Any, Set
 
 import pandas as pd
@@ -31,7 +32,6 @@
     is_mixed_with_object_dtype,
     numeric_normalize_types,
 )
-from cudf.utils.utils import cached_property
 
 
 class BaseIndex(Serializable):
diff --git a/python/cudf/cudf/core/column_accessor.py b/python/cudf/cudf/core/column_accessor.py
index 67976ac27d4..9cb86ca1cd2 100644
--- a/python/cudf/cudf/core/column_accessor.py
+++ b/python/cudf/cudf/core/column_accessor.py
@@ -4,7 +4,7 @@
 
 import itertools
 from collections.abc import MutableMapping
-from functools import reduce
+from functools import cached_property, reduce
 from typing import (
     TYPE_CHECKING,
     Any,
@@ -20,7 +20,6 @@
 
 import cudf
 from cudf.core import column
-from cudf.utils.utils import cached_property
 
 if TYPE_CHECKING:
     from cudf.core.column import ColumnBase
@@ -360,9 +359,9 @@ def select_by_index(self, index: Any) -> ColumnAccessor:
             start, stop, step = index.indices(len(self._data))
             keys = self.names[start:stop:step]
         elif pd.api.types.is_integer(index):
-            keys = [self.names[index]]
+            keys = (self.names[index],)
         else:
-            keys = (self.names[i] for i in index)
+            keys = tuple(self.names[i] for i in index)
         data = {k: self._data[k] for k in keys}
         return self.__class__(
             data, multiindex=self.multiindex, level_names=self.level_names,
diff --git a/python/cudf/cudf/core/frame.py b/python/cudf/cudf/core/frame.py
index a9e425f2012..1d207c7df6b 100644
--- a/python/cudf/cudf/core/frame.py
+++ b/python/cudf/cudf/core/frame.py
@@ -91,7 +91,7 @@ def _num_rows(self) -> int:
 
     @property
     def _column_names(self) -> List[Any]:  # TODO: List[str]?
-        return self._data.names
+        return list(self._data.names)
 
     @property
     def _index_names(self) -> List[Any]:  # TODO: List[str]?
@@ -105,7 +105,7 @@ def _index_names(self) -> List[Any]:  # TODO: List[str]?
 
     @property
     def _columns(self) -> List[Any]:  # TODO: List[Column]?
-        return self._data.columns
+        return list(self._data.columns)
 
     def serialize(self):
         header = {
diff --git a/python/cudf/cudf/core/groupby/groupby.py b/python/cudf/cudf/core/groupby/groupby.py
index ff700144bed..4bd14a2c47b 100644
--- a/python/cudf/cudf/core/groupby/groupby.py
+++ b/python/cudf/cudf/core/groupby/groupby.py
@@ -4,6 +4,7 @@
 import itertools
 import pickle
 import warnings
+from functools import cached_property
 
 import numpy as np
 import pandas as pd
@@ -16,7 +17,7 @@
 from cudf.core.abc import Serializable
 from cudf.core.column.column import arange, as_column
 from cudf.core.multiindex import MultiIndex
-from cudf.utils.utils import GetAttrGetItemMixin, cached_property
+from cudf.utils.utils import GetAttrGetItemMixin
 
 
 # The three functions below return the quantiles [25%, 50%, 75%]
diff --git a/python/cudf/cudf/core/index.py b/python/cudf/cudf/core/index.py
index f71f930a21c..b776c0217b9 100644
--- a/python/cudf/cudf/core/index.py
+++ b/python/cudf/cudf/core/index.py
@@ -5,6 +5,7 @@
 import math
 import pickle
 import warnings
+from functools import cached_property
 from numbers import Number
 from typing import (
     Any,
@@ -54,7 +55,7 @@
 from cudf.core.single_column_frame import SingleColumnFrame
 from cudf.utils.docutils import copy_docstring
 from cudf.utils.dtypes import find_common_type
-from cudf.utils.utils import cached_property, search_range
+from cudf.utils.utils import search_range
 
 T = TypeVar("T", bound="Frame")
 
diff --git a/python/cudf/cudf/core/indexed_frame.py b/python/cudf/cudf/core/indexed_frame.py
index fab5d75f62b..1496808a4d1 100644
--- a/python/cudf/cudf/core/indexed_frame.py
+++ b/python/cudf/cudf/core/indexed_frame.py
@@ -6,6 +6,7 @@
 import operator
 import warnings
 from collections import Counter, abc
+from functools import cached_property
 from typing import Callable, Type, TypeVar
 from uuid import uuid4
 
@@ -30,7 +31,6 @@
 from cudf.core.index import Index, RangeIndex, _index_from_columns
 from cudf.core.multiindex import MultiIndex
 from cudf.core.udf.utils import _compile_or_get, _supported_cols_from_frame
-from cudf.utils.utils import cached_property
 
 doc_reset_index_template = """
         Reset the index of the {klass}, or a level of it.
diff --git a/python/cudf/cudf/core/join/join.py b/python/cudf/cudf/core/join/join.py
index 39ff4718550..960bfa155fb 100644
--- a/python/cudf/cudf/core/join/join.py
+++ b/python/cudf/cudf/core/join/join.py
@@ -1,7 +1,7 @@
 # Copyright (c) 2020-2021, NVIDIA CORPORATION.
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Callable, cast
+from typing import TYPE_CHECKING, Any, Callable, List, cast
 
 import cudf
 from cudf import _lib as libcudf
@@ -320,7 +320,7 @@ def _sort_result(self, result: Frame) -> Frame:
         # same order as given in 'on'. If the indices are used as
         # keys, the index will be sorted. If one index is specified,
         # the key columns on the other side will be used to sort.
-        by = []
+        by: List[Any] = []
         if self._using_left_index and self._using_right_index:
             if result._index is not None:
                 by.extend(result._index._data.columns)
diff --git a/python/cudf/cudf/core/multiindex.py b/python/cudf/cudf/core/multiindex.py
index 8581b97c217..56826b18d45 100644
--- a/python/cudf/cudf/core/multiindex.py
+++ b/python/cudf/cudf/core/multiindex.py
@@ -6,6 +6,7 @@
 import numbers
 import pickle
 from collections.abc import Sequence
+from functools import cached_property
 from numbers import Integral
 from typing import Any, List, MutableMapping, Optional, Tuple, Union
 
@@ -22,11 +23,7 @@
 from cudf.core._compat import PANDAS_GE_120
 from cudf.core.frame import Frame
 from cudf.core.index import BaseIndex, _lexsorted_equal_range, as_index
-from cudf.utils.utils import (
-    NotIterable,
-    _maybe_indices_to_slice,
-    cached_property,
-)
+from cudf.utils.utils import NotIterable, _maybe_indices_to_slice
 
 
 class MultiIndex(Frame, BaseIndex, NotIterable):
diff --git a/python/cudf/cudf/utils/utils.py b/python/cudf/cudf/utils/utils.py
index 8571d9ffed5..4143cbd1d66 100644
--- a/python/cudf/cudf/utils/utils.py
+++ b/python/cudf/cudf/utils/utils.py
@@ -144,28 +144,6 @@ def set_allocator(
 IS_NEP18_ACTIVE = _is_nep18_active()
 
 
-class cached_property:
-    """
-    Like @property, but only evaluated upon first invocation.
-    To force re-evaluation of a cached_property, simply delete
-    it with `del`.
-    """
-
-    # TODO: Can be replaced with functools.cached_property when we drop support
-    # for Python 3.7.
-
-    def __init__(self, func):
-        self.func = func
-
-    def __get__(self, instance, cls):
-        if instance is None:
-            return self
-        else:
-            value = self.func(instance)
-            object.__setattr__(instance, self.func.__name__, value)
-            return value
-
-
 class GetAttrGetItemMixin:
     """This mixin changes `__getattr__` to attempt a `__getitem__` call.
 

From 1c73cc0bc7c88735210b58b7e6acc477d391786b Mon Sep 17 00:00:00 2001
From: Ashwin Srinath <shwina@users.noreply.github.com>
Date: Fri, 11 Feb 2022 16:29:22 -0500
Subject: [PATCH 2/3] Update copyright years

---
 python/cudf/cudf/core/_base_index.py   | 2 +-
 python/cudf/cudf/core/index.py         | 2 +-
 python/cudf/cudf/core/indexed_frame.py | 2 +-
 python/cudf/cudf/core/join/join.py     | 2 +-
 python/cudf/cudf/core/multiindex.py    | 2 +-
 5 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/python/cudf/cudf/core/_base_index.py b/python/cudf/cudf/core/_base_index.py
index 1d8d04e897b..08ef159ec54 100644
--- a/python/cudf/cudf/core/_base_index.py
+++ b/python/cudf/cudf/core/_base_index.py
@@ -1,4 +1,4 @@
-# Copyright (c) 2021, NVIDIA CORPORATION.
+# Copyright (c) 2021-2022, NVIDIA CORPORATION.
 
 from __future__ import annotations
 
diff --git a/python/cudf/cudf/core/index.py b/python/cudf/cudf/core/index.py
index b776c0217b9..5b60e8dbd1c 100644
--- a/python/cudf/cudf/core/index.py
+++ b/python/cudf/cudf/core/index.py
@@ -1,4 +1,4 @@
-# Copyright (c) 2018-2021, NVIDIA CORPORATION.
+# Copyright (c) 2018-2022, NVIDIA CORPORATION.
 
 from __future__ import annotations
 
diff --git a/python/cudf/cudf/core/indexed_frame.py b/python/cudf/cudf/core/indexed_frame.py
index 1496808a4d1..6d1f375b68c 100644
--- a/python/cudf/cudf/core/indexed_frame.py
+++ b/python/cudf/cudf/core/indexed_frame.py
@@ -1,4 +1,4 @@
-# Copyright (c) 2021, NVIDIA CORPORATION.
+# Copyright (c) 2021-2022, NVIDIA CORPORATION.
 """Base class for Frame types that have an index."""
 
 from __future__ import annotations
diff --git a/python/cudf/cudf/core/join/join.py b/python/cudf/cudf/core/join/join.py
index 960bfa155fb..c7e46cf0165 100644
--- a/python/cudf/cudf/core/join/join.py
+++ b/python/cudf/cudf/core/join/join.py
@@ -1,4 +1,4 @@
-# Copyright (c) 2020-2021, NVIDIA CORPORATION.
+# Copyright (c) 2020-2022, NVIDIA CORPORATION.
 from __future__ import annotations
 
 from typing import TYPE_CHECKING, Any, Callable, List, cast
diff --git a/python/cudf/cudf/core/multiindex.py b/python/cudf/cudf/core/multiindex.py
index 56826b18d45..5e0cd2ca8cb 100644
--- a/python/cudf/cudf/core/multiindex.py
+++ b/python/cudf/cudf/core/multiindex.py
@@ -1,4 +1,4 @@
-# Copyright (c) 2019-2021, NVIDIA CORPORATION.
+# Copyright (c) 2019-2022, NVIDIA CORPORATION.
 
 from __future__ import annotations
 

From 67688259cb3302483ba70af3262fb4fc399b10c9 Mon Sep 17 00:00:00 2001
From: Ashwin Srinath <shwina@users.noreply.github.com>
Date: Mon, 14 Feb 2022 14:32:01 -0500
Subject: [PATCH 3/3] Return a Tuple, not a List

---
 python/cudf/cudf/core/frame.py | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/python/cudf/cudf/core/frame.py b/python/cudf/cudf/core/frame.py
index dad41712679..be556d005ea 100644
--- a/python/cudf/cudf/core/frame.py
+++ b/python/cudf/cudf/core/frame.py
@@ -90,22 +90,22 @@ def _num_rows(self) -> int:
         return len(self._data.columns[0])
 
     @property
-    def _column_names(self) -> List[Any]:  # TODO: List[str]?
-        return list(self._data.names)
+    def _column_names(self) -> Tuple[Any, ...]:  # TODO: Tuple[str]?
+        return tuple(self._data.names)
 
     @property
-    def _index_names(self) -> List[Any]:  # TODO: List[str]?
+    def _index_names(self) -> Optional[Tuple[Any, ...]]:  # TODO: Tuple[str]?
         # TODO: Temporarily suppressing mypy warnings to avoid introducing bugs
         # by returning an empty list where one is not expected.
         return (
             None  # type: ignore
             if self._index is None
-            else self._index._data.names
+            else tuple(self._index._data.names)
         )
 
     @property
-    def _columns(self) -> List[Any]:  # TODO: List[Column]?
-        return list(self._data.columns)
+    def _columns(self) -> Tuple[Any, ...]:  # TODO: Tuple[Column]?
+        return tuple(self._data.columns)
 
     def serialize(self):
         header = {