Add functools32 to TensorFlow dependencies.

This library is a backport for Python 2 of the Python 3 functools standard library. We want to use functools.lru_cache for caching opt_einsum results.

One other option is adding backports/functools_lru_cache. But functools also has other components which might be useful.

PiperOrigin-RevId: 257299040

tensorflow/opensource_only.files

@@ -212,6 +212,7 @@ tensorflow/third_party/nccl/BUILD
 tensorflow/third_party/boringssl/BUILD
 tensorflow/third_party/mpi/.gitignore
 tensorflow/third_party/mpi/BUILD
+tensorflow/third_party/functools32.BUILD
 tensorflow/third_party/tensorrt/LICENSE
 tensorflow/third_party/tensorrt/BUILD
 tensorflow/third_party/tensorrt/build_defs.bzl.tpl

tensorflow/python/BUILD

@@ -3555,6 +3555,7 @@ py_library(
         ":math_ops",
         ":platform",
         "//tensorflow/compiler/tf2xla/ops:gen_xla_ops",
+        "@functools32_archive//:functools32",
         "@opt_einsum_archive//:opt_einsum",
     ],
 )

tensorflow/tools/pip_package/BUILD

@@ -171,6 +171,7 @@ filegroup(
         "@farmhash_archive//:COPYING",
         "@fft2d//:fft2d/readme2d.txt",
         "@flatbuffers//:LICENSE.txt",
+        "@functools32_archive//:LICENSE",
         "@gast_archive//:PKG-INFO",
         "@gemmlowp//:LICENSE",
         "@gif_archive//:COPYING",

tensorflow/tools/pip_package/setup.py

@@ -88,6 +88,8 @@ else:
   REQUIRED_PACKAGES.append('wheel')
   # mock comes with unittest.mock for python3, need to install for python2
   REQUIRED_PACKAGES.append('mock >= 2.0.0')
+  # functools comes with python3, need to install the backport for python2
+  REQUIRED_PACKAGES.append('functools32 >= 3.2.3')
 
 # tf-nightly should depend on tb-nightly
 if 'tf_nightly' in project_name:

tensorflow/workspace.bzl

@@ -316,6 +316,17 @@ def tf_repositories(path_prefix = "", tf_repo_name = ""):
         ],
     )
 
+    tf_http_archive(
+        name = "functools32_archive",
+        build_file = clean_dep("//third_party:functools32.BUILD"),
+        sha256 = "f6253dfbe0538ad2e387bd8fdfd9293c925d63553f5813c4e587745416501e6d",
+        strip_prefix = "functools32-3.2.3-2",
+        urls = [
+            "http://mirror.tensorflow.org/pypi.python.org/packages/c5/60/6ac26ad05857c601308d8fb9e87fa36d0ebf889423f47c3502ef034365db/functools32-3.2.3-2.tar.gz",
+            "https://pypi.python.org/packages/c5/60/6ac26ad05857c601308d8fb9e87fa36d0ebf889423f47c3502ef034365db/functools32-3.2.3-2.tar.gz",
+        ],
+    )
+
     tf_http_archive(
         name = "gast_archive",
         build_file = clean_dep("//third_party:gast.BUILD"),

third_party/functools32.BUILD

@@ -0,0 +1,18 @@
+# Description:
+#   functools32 provides a backport of the functools module for Python 2.
+
+licenses(["notice"])  # Python 2.0
+
+exports_files(["LICENSE"])
+
+py_library(
+    name = "functools32",
+    srcs = [
+        "functools32/__init__.py",
+        "functools32/_dummy_thread32.py",
+        "functools32/functools32.py",
+        "functools32/reprlib32.py",
+    ],
+    srcs_version = "PY2AND3",
+    visibility = ["//visibility:public"],
+)