Implement Variant changes suggested by Manjunath Kudlur; simplify API.

1. Remove the self-mutating MaybeDecodeAndGet<>() in favor of the simple,
   original get<>().
2. Remove mutexes and locks from everything.

To allow tensorflow RPC to continue working transparently:

3. Add a registration mechanism for Variant decoding -- used by
   variant_coding within TensorFlow.
4. Add a MaybeDecodeAndCopy<>() const; for use by callers of Session::Run
   that get Tensors back which may contain encoded Variants.
5. Small bugfixes to Variant Encode impls and tensor FromProtoField and
   variant_coding.

PiperOrigin-RevId: 166383211

1 files changed, 7 insertions, 8 deletions

diff --git a/tensorflow/core/framework/variant_op_copy_test.cc b/tensorflow/core/framework/variant_op_copy_test.cc
index ff3415cb50..f02c572681 100644
--- a/tensorflow/core/framework/variant_op_copy_test.cc
+++ b/tensorflow/core/framework/variant_op_copy_test.cc
@@ -28,6 +28,7 @@ limitations under the License.
 #include "tensorflow/core/framework/types.h"
 #include "tensorflow/core/framework/variant.h"
 #include "tensorflow/core/framework/variant_encode_decode.h"
+#include "tensorflow/core/framework/variant_op_registry.h"
 #include "tensorflow/core/framework/variant_tensor_data.h"
 #include "tensorflow/core/graph/node_builder.h"
 #include "tensorflow/core/lib/core/status_test_util.h"
@@ -48,6 +49,8 @@ struct StoredTensorValue {
   }
 };
 
+REGISTER_UNARY_VARIANT_DECODE_FUNCTION(StoredTensorValue, "StoredTensorValue");
+
 REGISTER_OP("CreateTestVariant")
     .Output("output: variant")
     .SetShapeFn(shape_inference::UnknownShape);
@@ -112,16 +115,12 @@ TEST(VariantOpCopyTest, CreateCopyCPUToCPU) {
   std::vector<Tensor> outputs;
   TF_EXPECT_OK(session.Run({create_op, identity}, &outputs));
   EXPECT_EQ(2, outputs.size());
-  Variant& r1 = outputs[1].scalar<Variant>()();
+  const Variant& r1 = outputs[1].scalar<Variant>()();
 
-  // Accessing the object more than once does not change its behavior (even
-  // though the first access performed a deserialization step).
-  EXPECT_EQ("StoredTensorValue", r1.TypeName());
-  EXPECT_EQ(42, CHECK_NOTNULL(r1.MaybeDecodeAndGet<StoredTensorValue>())
-                    ->stored.scalar<int32>()());
   EXPECT_EQ("StoredTensorValue", r1.TypeName());
-  EXPECT_EQ(42, CHECK_NOTNULL(r1.MaybeDecodeAndGet<StoredTensorValue>())
-                    ->stored.scalar<int32>()());
+  const StoredTensorValue* v1 = r1.get<StoredTensorValue>();
+  EXPECT_NE(v1, nullptr);
+  EXPECT_EQ(42, v1->stored.scalar<int32>()());
 }
 
 }  // end namespace tensorflow