// `keep_alive_secs` of inactivity.
  virtual Status SetOrUpdateServerDef(const ServerDef& server_def,
                                      bool reset_context, int keep_alive_secs,
                                      int64_t init_timeout_in_ms, int retries,
                                      bool clear_existing_contexts = false) = 0;

  // Initializes context for the local worker and no contexts will be created

};

struct TFE_MonitoringBoolGauge0 : TFE_MonitoringGauge<bool, 0> {
  using TFE_MonitoringGauge::TFE_MonitoringGauge;
};
struct TFE_MonitoringBoolGauge1 : TFE_MonitoringGauge<bool, 1> {
  using TFE_MonitoringGauge::TFE_MonitoringGauge;
};
struct TFE_MonitoringBoolGauge2 : TFE_MonitoringGauge<bool, 2> {
  using TFE_MonitoringGauge::TFE_MonitoringGauge;
};

struct TFE_MonitoringBuckets {

  // Hint: use c.release()() to run early.
  F release() {
    released_ = true;
    return std::move(f_);
  }

  bool is_released() const { return released_; }

 private:
  static_assert(!std::is_reference<F>::value, "F must not be a reference");

  bool released_ = false;
  F f_;
};

template <int&... ExplicitParameterBarrier, typename F,
          typename DecayF = typename std::decay<F>::type>

namespace tensorflow {
namespace gradients {
namespace internal {

void CompareNumericalAndAutodiffGradients(
    Model model, Model grad_model, AbstractContext* ctx,
    absl::Span<AbstractTensorHandle* const> inputs, bool use_function,
    double abs_error = 1e-2);

void CheckTensorValue(AbstractTensorHandle* t, absl::Span<const float> manuals,
                      absl::Span<const int64_t> dims, double abs_error = 1e-2);

  absl::StatusOr<core::RefCountPtr<FunctionRecord>> GetFunctionRecord()
      override {
    return func_record_.GetNewRef();
  }

  // For LLVM style RTTI.
  static bool classof(const AbstractFunction* ptr) {
    return ptr->getKind() == kGraph;
  }

 private:
  core::RefCountPtr<FunctionRecord> func_record_;
};
}  // namespace graph
}  // namespace tracing

  virtual Status SetAttrInt(const char* attr_name, int64_t value) = 0;
  virtual Status SetAttrFloat(const char* attr_name, float value) = 0;
  virtual Status SetAttrBool(const char* attr_name, bool value) = 0;
  virtual Status SetAttrType(const char* attr_name, DataType value) = 0;
  virtual Status SetAttrShape(const char* attr_name, const int64_t* dims,
                              const int num_dims) = 0;

// be included in the output properties.
TF_CAPI_EXPORT extern void TF_InferStatically(
    TF_GraphProperties* graph_properties, TF_Bool assume_valid_feeds,
    TF_Bool aggressive_shape_inference, TF_Bool include_input_tensor_values,
    TF_Bool include_output_tensor_values, TF_Status* s);

// Get the size of input OpInfo::TensorProperties given node name.
TF_CAPI_EXPORT extern void TF_GetInputPropertiesListSize(

typedef struct TFE_MonitoringBoolGaugeCell TFE_MonitoringBoolGaugeCell;
TF_CAPI_EXPORT extern void TFE_MonitoringBoolGaugeCellSet(
    TFE_MonitoringBoolGaugeCell* cell, bool value);
TF_CAPI_EXPORT extern bool TFE_MonitoringBoolGaugeCellValue(
    TFE_MonitoringBoolGaugeCell* cell);

// APIs for Bool Gauge without label.
typedef struct TFE_MonitoringBoolGauge0 TFE_MonitoringBoolGauge0;
TF_CAPI_EXPORT extern TFE_MonitoringBoolGauge0* TFE_MonitoringNewBoolGauge0(

  // with key `key` existed after the call.
  bool Delete(const std::string& key) {
    absl::MutexLock lock(&mu_);
    return DeleteLocked(key);
  }

  /// Look up the entry with key `key` and copy it to `value` if found. Returns
  /// true if an entry was found for `key`, and its timestamp is not more than
  /// max_age_ seconds in the past.
  bool Lookup(const std::string& key, T* value) {
    if (max_age_ == 0) {

  // Following two methods are used to support custom device.
  // Return true if the inputs contain custom device tensor handle. It means
  // that the argument need to be handled by a custom device.
  virtual bool HasCustomDeviceInput() const = 0;

  virtual const tensorflow::OpDef* OpDef() const = 0;

  virtual Status InputLength(const char* input_name, int* length) = 0;