From 94a73f439383defabce00ea3cffa20920c2a7dc6 Mon Sep 17 00:00:00 2001
From: Edward Loper <edloper@google.com>
Date: Fri, 5 Jun 2020 14:24:34 -0700
Subject: [PATCH] Replace the mechanism used to register & look up Python types
 from c code in tensorflow/python/util.h with one that supports non-type
 symbols as well.

PiperOrigin-RevId: 314996128
Change-Id: I8edca2552d5d45cf74a1f5fb00bc88996af033da
---
 tensorflow/python/util/util.cc         | 56 +++++++++++++++++---------
 tensorflow/python/util/util.h          | 15 ++++++-
 tensorflow/python/util/util_wrapper.cc |  4 ++
 3 files changed, 55 insertions(+), 20 deletions(-)

diff --git a/tensorflow/python/util/util.cc b/tensorflow/python/util/util.cc
index 1d0dd695d74..cf8581443e7 100644
--- a/tensorflow/python/util/util.cc
+++ b/tensorflow/python/util/util.cc
@@ -29,15 +29,25 @@ limitations under the License.
 namespace tensorflow {
 namespace swig {
 
-std::unordered_map<string, PyObject*>* PythonTypesMap() {
+namespace {
+string PyObjectToString(PyObject* o);
+}  // namespace
+
+std::unordered_map<string, PyObject*>* RegisteredPyObjectMap() {
   static auto* m = new std::unordered_map<string, PyObject*>();
   return m;
 }
 
-PyObject* GetRegisteredType(const string& key) {
-  auto* m = PythonTypesMap();
-  auto it = m->find(key);
-  if (it == m->end()) return nullptr;
+PyObject* GetRegisteredPyObject(const string& name) {
+  const auto* m = RegisteredPyObjectMap();
+  auto it = m->find(name);
+  if (it == m->end()) {
+    PyErr_SetString(PyExc_TypeError,
+                    tensorflow::strings::StrCat("No object with name ", name,
+                                                " has been registered.")
+                        .c_str());
+    return nullptr;
+  }
   return it->second;
 }
 
@@ -49,26 +59,35 @@ PyObject* RegisterType(PyObject* type_name, PyObject* type) {
                         .c_str());
     return nullptr;
   }
+  return RegisterPyObject(type_name, type);
+}
 
+PyObject* RegisterPyObject(PyObject* name, PyObject* value) {
   string key;
-  if (PyBytes_Check(type_name)) {
-    key = PyBytes_AsString(type_name);
-  }
+  if (PyBytes_Check(name)) {
+    key = PyBytes_AsString(name);
 #if PY_MAJOR_VERSION >= 3
-  if (PyUnicode_Check(type_name)) {
-    key = PyUnicode_AsUTF8(type_name);
-  }
+  } else if (PyUnicode_Check(name)) {
+    key = PyUnicode_AsUTF8(name);
 #endif
-
-  if (PythonTypesMap()->find(key) != PythonTypesMap()->end()) {
+  } else {
     PyErr_SetString(PyExc_TypeError, tensorflow::strings::StrCat(
-                                         "Type already registered for ", key)
+                                         "Expected name to be a str, got",
+                                         PyObjectToString(name))
                                          .c_str());
     return nullptr;
   }
 
-  Py_INCREF(type);
-  PythonTypesMap()->emplace(key, type);
+  auto* m = RegisteredPyObjectMap();
+  if (m->find(key) != m->end()) {
+    PyErr_SetString(PyExc_TypeError, tensorflow::strings::StrCat(
+                                         "Value already registered for ", key)
+                                         .c_str());
+    return nullptr;
+  }
+
+  Py_INCREF(value);
+  m->emplace(key, value);
 
   Py_RETURN_NONE;
 }
@@ -196,7 +215,7 @@ class CachedTypeCheck {
 // Returns 0 otherwise.
 // Returns -1 if an error occurred (e.g., if 'type_name' is not registered.)
 int IsInstanceOfRegisteredType(PyObject* obj, const char* type_name) {
-  PyObject* type_obj = GetRegisteredType(type_name);
+  PyObject* type_obj = GetRegisteredPyObject(type_name);
   if (TF_PREDICT_FALSE(type_obj == nullptr)) {
     PyErr_SetString(PyExc_RuntimeError,
                     tensorflow::strings::StrCat(
@@ -513,7 +532,8 @@ class AttrsValueIterator : public ValueIterator {
 };
 
 bool IsSparseTensorValueType(PyObject* o) {
-  PyObject* sparse_tensor_value_type = GetRegisteredType("SparseTensorValue");
+  PyObject* sparse_tensor_value_type =
+      GetRegisteredPyObject("SparseTensorValue");
   if (TF_PREDICT_FALSE(sparse_tensor_value_type == nullptr)) {
     return false;
   }
diff --git a/tensorflow/python/util/util.h b/tensorflow/python/util/util.h
index 23438b43c53..fc0b864416e 100644
--- a/tensorflow/python/util/util.h
+++ b/tensorflow/python/util/util.h
@@ -19,6 +19,8 @@ limitations under the License.
 
 #include <Python.h>
 
+#include <string>
+
 namespace tensorflow {
 namespace swig {
 
@@ -270,11 +272,20 @@ PyObject* FlattenForData(PyObject* nested);
 PyObject* AssertSameStructureForData(PyObject* o1, PyObject* o2,
                                      bool check_types);
 
-// RegisterType is used to pass PyTypeObject (which is defined in python) for an
-// arbitrary identifier `type_name` into C++.
+// Registers a Python object so it can be looked up from c++.  The set of
+// valid names, and the expected values for those names, are listed in
+// the documentation for `RegisteredPyObjects`.  Returns PyNone.
+PyObject* RegisterPyObject(PyObject* name, PyObject* value);
+
+// Variant of RegisterPyObject that requires the object's value to be a type.
 PyObject* RegisterType(PyObject* type_name, PyObject* type);
 
 }  // namespace swig
+
+// Returns a borrowed reference to an object that was registered with
+// RegisterPyObject.  (Do not call PY_DECREF on the result).
+PyObject* GetRegisteredPyObject(const std::string& name);
+
 }  // namespace tensorflow
 
 #endif  // TENSORFLOW_PYTHON_UTIL_UTIL_H_
diff --git a/tensorflow/python/util/util_wrapper.cc b/tensorflow/python/util/util_wrapper.cc
index dd74306413c..63c70d785cc 100644
--- a/tensorflow/python/util/util_wrapper.cc
+++ b/tensorflow/python/util/util_wrapper.cc
@@ -30,6 +30,10 @@ PYBIND11_MODULE(_pywrap_utils, m) {
           return tensorflow::PyoOrThrow(
               tensorflow::swig::RegisterType(type_name.ptr(), type.ptr()));
         });
+  m.def("RegisterPyObject", [](const py::handle& name, const py::handle& type) {
+    return tensorflow::PyoOrThrow(
+        tensorflow::swig::RegisterPyObject(name.ptr(), type.ptr()));
+  });
   m.def(
       "IsTensor",
       [](const py::handle& o) {