Serialize FunctionSpec as proto instead of a tuple.

PiperOrigin-RevId: 229174621

tensorflow/python/eager/function.py

@@ -866,14 +866,6 @@ def _deterministic_dict_values(dictionary):
 class FunctionSpec(object):
   """Specification of how to bind arguments to a function."""
 
-  def as_tuple(self):
-    return (self._fullargspec, self._is_method, self._args_to_prepend,
-            self._kwargs_to_include, self.input_signature)
-
-  @staticmethod
-  def from_tuple(spec_tuple):
-    return FunctionSpec(*spec_tuple)
-
   @staticmethod
   def from_function_and_signature(python_function, input_signature):
     """Create a FunctionSpec instance given a python function and signature."""
@@ -920,7 +912,7 @@ class FunctionSpec(object):
     }
     self._default_values_start_index = offset
     if input_signature is None:
-      self.input_signature = None
+      self._input_signature = None
     else:
       if fullargspec.varkw is not None or fullargspec.kwonlyargs:
         raise ValueError("Cannot define a TensorFlow function from a Python "
@@ -931,8 +923,32 @@ class FunctionSpec(object):
         raise TypeError("input_signature must be either a tuple or a "
                         "list, received " + str(type(input_signature)))
 
-      self.input_signature = tuple(input_signature)
-      self.flat_input_signature = tuple(nest.flatten(input_signature))
+      self._input_signature = tuple(input_signature)
+      self._flat_input_signature = tuple(nest.flatten(input_signature))
+
+  @property
+  def fullargspec(self):
+    return self._fullargspec
+
+  @property
+  def is_method(self):
+    return self._is_method
+
+  @property
+  def args_to_prepend(self):
+    return self._args_to_prepend
+
+  @property
+  def kwargs_to_include(self):
+    return self._kwargs_to_include
+
+  @property
+  def input_signature(self):
+    return self._input_signature
+
+  @property
+  def flat_input_signature(self):
+    return self._flat_input_signature
 
   def canonicalize_function_inputs(self, *args, **kwargs):
     """Canonicalizes `args` and `kwargs`.
@@ -980,7 +996,7 @@ class FunctionSpec(object):
         if index is not None:
           arg_indices_to_values[index] = value
           consumed_args.append(arg)
-        elif self.input_signature is not None:
+        elif self._input_signature is not None:
           raise ValueError("Cannot define a TensorFlow function from a Python "
                            "function with keyword arguments when "
                            "input_signature is provided.")
@@ -1003,12 +1019,13 @@ class FunctionSpec(object):
     if need_packing:
       inputs = nest.pack_sequence_as(
           structure=inputs, flat_sequence=flat_inputs)
-    if self.input_signature is None:
+    if self._input_signature is None:
       return inputs, kwargs
     else:
       assert not kwargs
-      signature_relevant_inputs = inputs[:len(self.input_signature)]
-      if not is_same_structure(self.input_signature, signature_relevant_inputs):
+      signature_relevant_inputs = inputs[:len(self._input_signature)]
+      if not is_same_structure(self._input_signature,
+                               signature_relevant_inputs):
         raise ValueError("Structure of Python function inputs does not match "
                          "input_signature.")
       signature_inputs_flat = nest.flatten(signature_relevant_inputs)
@@ -1017,10 +1034,10 @@ class FunctionSpec(object):
         raise ValueError("When input_signature is provided, all inputs to "
                          "the Python function must be Tensors.")
       if any(not spec.is_compatible_with(other) for spec, other in zip(
-          self.flat_input_signature, signature_inputs_flat)):
+          self._flat_input_signature, signature_inputs_flat)):
         raise ValueError("Python inputs incompatible with input_signature: "
                          "inputs (%s), input_signature (%s)" %
-                         (str(inputs), str(self.input_signature)))
+                         (str(inputs), str(self._input_signature)))
       return inputs, {}
 
 

tensorflow/python/saved_model/function_deserialization.py

@@ -60,6 +60,17 @@ def _inputs_compatible(args, stored_inputs):
   return True
 
 
+def _deserialize_function_spec(function_spec_proto, coder):
+  """Deserialize a FunctionSpec object from its proto representation."""
+  fullargspec = coder.decode_proto(function_spec_proto.fullargspec)
+  is_method = function_spec_proto.is_method
+  args_to_prepend = coder.decode_proto(function_spec_proto.args_to_prepend)
+  kwargs_to_include = coder.decode_proto(function_spec_proto.kwargs_to_include)
+  input_signature = coder.decode_proto(function_spec_proto.input_signature)
+  return function_lib.FunctionSpec(fullargspec, is_method, args_to_prepend,
+                                   kwargs_to_include, input_signature)
+
+
 def recreate_polymorphic_function(
     saved_polymorphic_function, functions):
   """Creates a PolymorphicFunction from a SavedPolymorphicFunction.
@@ -77,9 +88,8 @@ def recreate_polymorphic_function(
   # serialization cycle.
 
   coder = nested_structure_coder.StructureCoder()
-  function_spec_tuple = coder.decode_proto(
-      saved_polymorphic_function.function_spec_tuple)
-  function_spec = function_lib.FunctionSpec.from_tuple(function_spec_tuple)
+  function_spec = _deserialize_function_spec(
+      saved_polymorphic_function.function_spec, coder)
 
   # TODO(mdan): We may enable autograph once exceptions are supported.
   @def_function.function(autograph=False)

tensorflow/python/saved_model/function_serialization.py

@@ -25,13 +25,28 @@ from tensorflow.python.saved_model import saved_object_graph_pb2
 from tensorflow.python.util import nest
 
 
+def _serialize_function_spec(function_spec, coder):
+  """Serialize a FunctionSpec object into its proto representation."""
+  proto = saved_object_graph_pb2.FunctionSpec()
+  proto.fullargspec.CopyFrom(coder.encode_structure(function_spec.fullargspec))
+  proto.is_method = function_spec.is_method
+  proto.args_to_prepend.CopyFrom(
+      coder.encode_structure(function_spec.args_to_prepend))
+  proto.kwargs_to_include.CopyFrom(
+      coder.encode_structure(function_spec.kwargs_to_include))
+  proto.input_signature.CopyFrom(
+      coder.encode_structure(function_spec.input_signature))
+  return proto
+
+
 def serialize_polymorphic_function(polymorphic_function, node_ids):
   """Build a SavedPolymorphicProto."""
   coder = nested_structure_coder.StructureCoder()
   proto = saved_object_graph_pb2.SavedPolymorphicFunction()
 
-  proto.function_spec_tuple.CopyFrom(
-      coder.encode_structure(polymorphic_function.function_spec.as_tuple()))  # pylint: disable=protected-access
+  function_spec_proto = _serialize_function_spec(
+      polymorphic_function.function_spec, coder)
+  proto.function_spec.CopyFrom(function_spec_proto)
   for signature, concrete_function in list_all_concrete_functions(
       polymorphic_function):
     bound_inputs = []

tensorflow/python/saved_model/saved_object_graph.proto

@@ -86,9 +86,7 @@ message SavedAsset {
 // A function with multiple signatures, possibly with non-Tensor arguments.
 message SavedPolymorphicFunction {
   repeated SavedMonomorphicFunction monomorphic_function = 1;
-  // Tuple representing a `FunctionSpec`.
-  // TODO(vbardiovsky): Make this a proto.
-  StructuredValue function_spec_tuple = 2;
+  FunctionSpec function_spec = 2;
 }
 
 message SavedMonomorphicFunction {
@@ -118,3 +116,20 @@ message SavedVariable {
 
   // TODO(andresp): Add save_slice_info_def?
 }
+
+// Represents FunctionSpec used in PolymorphicFunction. This represents a
+// function that has been wrapped as a PolymorphicFunction.
+message FunctionSpec {
+  // Full arg spec from inspect.getfullargspec().
+  StructuredValue fullargspec = 1;
+  // Whether this represents a class method.
+  bool is_method = 2;
+  // Which arguments to always prepend, in case the original function is based
+  // on a functools.partial.
+  StructuredValue args_to_prepend = 3;
+  // Which kwargs to always include, in case the original function is based on a
+  // functools.partial.
+  StructuredValue kwargs_to_include = 4;
+  // The input signature, if specified.
+  StructuredValue input_signature = 5;
+}