[Tensorflow] Expose API to lookup TensorSlice.

Change: 150384503

tensorflow/core/util/tensor_bundle/tensor_bundle.cc

@@ -712,6 +712,18 @@ Status BundleReader::Lookup(StringPiece key, Tensor* val) {
   }
 }
 
+Status BundleReader::LookupTensorSlices(StringPiece key,
+                                        std::vector<TensorSlice>* slices) {
+  slices->clear();
+  BundleEntryProto entry;
+  TF_RETURN_IF_ERROR(GetBundleEntryProto(key, &entry));
+  slices->reserve(entry.slices_size());
+  for (const auto& slice : entry.slices()) {
+    slices->emplace_back(slice);
+  }
+  return Status::OK();
+}
+
 Status BundleReader::LookupSlice(StringPiece full_tensor_key,
                                  const TensorSlice& slice_spec, Tensor* val) {
   BundleEntryProto entry;

tensorflow/core/util/tensor_bundle/tensor_bundle.h

@@ -207,6 +207,12 @@ class BundleReader {
   // REQUIRES: status().ok()
   Status Lookup(StringPiece key, Tensor* val) TF_MUST_USE_RESULT;
 
+  // Looks up the slices of the tensor keyed by "key".  On OK, "slices"
+  // is non-empty if and only if the tensor is a partitioned tensor.
+  // REQUIRES: status().ok()
+  Status LookupTensorSlices(StringPiece key, std::vector<TensorSlice>* slices)
+      TF_MUST_USE_RESULT;
+
   // Looks up a specific slice of a partitioned tensor.
   // It is only required that the stored slices cover the requested slice,
   // namely "slice_spec" is a subset of the union of the stored slices.

tensorflow/core/util/tensor_bundle/tensor_bundle_test.cc

@@ -245,15 +245,14 @@ TEST(TensorBundleTest, PartitionedVariables) {
   // Adds two slices.
   // First slice: column 0, all zeros.
   // Second slice: column 1 to rest, all ones.
+  TensorSlice slice1 = TensorSlice::ParseOrDie("-:0,1");
+  TensorSlice slice2 = TensorSlice::ParseOrDie("-:1,9");
   {
     BundleWriter writer(Env::Default(), Prefix("foo"));
-    TensorSlice slice = TensorSlice::ParseOrDie("-:0,1");
 
-    TF_ASSERT_OK(writer.AddSlice("foo", kFullShape,
-                                 TensorSlice::ParseOrDie("-:0,1"),
+    TF_ASSERT_OK(writer.AddSlice("foo", kFullShape, slice1,
                                  Constant<float>(0., TensorShape({5, 1}))));
-    TF_ASSERT_OK(writer.AddSlice("foo", kFullShape,
-                                 TensorSlice::ParseOrDie("-:1,9"),
+    TF_ASSERT_OK(writer.AddSlice("foo", kFullShape, slice2,
                                  Constant<float>(1., TensorShape({5, 9}))));
     TF_ASSERT_OK(writer.Finish());
   }
@@ -274,6 +273,18 @@ TEST(TensorBundleTest, PartitionedVariables) {
     TF_ASSERT_OK(reader.Lookup("foo", &val));
     test::ExpectTensorEqual<float>(val, expected_val);
   }
+  // Reads all slices.
+  {
+    BundleReader reader(Env::Default(), Prefix("foo"));
+    TF_ASSERT_OK(reader.status());
+
+    std::vector<TensorSlice> slices;
+    TF_ASSERT_OK(reader.LookupTensorSlices("foo", &slices));
+
+    EXPECT_EQ(2, slices.size());
+    EXPECT_EQ(slice1.DebugString(), slices[0].DebugString());
+    EXPECT_EQ(slice2.DebugString(), slices[1].DebugString());
+  }
   // Reads a slice consisting of first two columns, "cutting" both slices.
   {
     BundleReader reader(Env::Default(), Prefix("foo"));