Function CompressRepeatedField

tensorflow/core/framework/tensor_util.cc:269–310

template <typename T>
bool CompressRepeatedField(float min_compression_ratio,
                           const TensorShape& shape, TensorProto* tensor) {
  using TypeHelper = internal::TensorProtoHelper<T>;
  using FieldType = typename internal::TensorProtoHelper<T>::FieldType;
  const int64 num_tensor_values = shape.num_elements();
  // Notice that for complex types the tensor is stored as an array of up to
  // 2 * num_tensor_values real values (real and imaginary parts), possibly
  // truncated.
  const int64 num_proto_values = TypeHelper::NumValues(*tensor);
  if (num_proto_values != num_tensor_values) {
    // Already compressed or invalid.
    return false;
  }
  const T last_value = TypeHelper::GetValue(num_proto_values - 1, *tensor);
  int64 last_index = 0;
  for (int64 i = num_proto_values - 2; i >= 0 && last_index == 0; --i) {
    const T cur_value = TypeHelper::GetValue(i, *tensor);
    if (PackedValuesNotEqual(cur_value, last_value)) {
      last_index = i + 1;
    }
  }
  const int64 num_truncated_proto_values = last_index + 1;
  const int64 num_bytes_as_field =
      num_truncated_proto_values * sizeof(FieldType);
  const int64 num_bytes_as_tensor_content = num_tensor_values * sizeof(T);
  const int64 num_bytes_before = num_proto_values * sizeof(FieldType);
  if (std::min(num_bytes_as_field, num_bytes_as_tensor_content) >
      static_cast<int64>(num_bytes_before / min_compression_ratio)) {
    return false;
  }
  if (num_bytes_as_field <= num_bytes_as_tensor_content) {
    TypeHelper::Truncate(num_truncated_proto_values, tensor);
  } else {
    gtl::InlinedVector<T, 64> tmp(num_tensor_values);
    TypeHelper::CopyValues(tmp.begin(), *tensor);
    TypeHelper::Truncate(0, tensor);
    port::CopyFromArray(tensor->mutable_tensor_content(),
                        reinterpret_cast<const char*>(tmp.data()),
                        num_bytes_as_tensor_content);
  }
  return true;
}

template <typename T>
bool CompressTensorProtoInPlaceImpl(int64 min_num_elements,