int64_t init_timeout_in_ms, int retries, TF_Status* status,
    bool clear_existing_contexts);

// Checks whether a remote worker is alive or not. This will return true even if
// the context doesn't exist on the remote worker.
TF_CAPI_EXPORT extern bool TFE_ContextCheckAlive(TFE_Context* ctx,
                                                 const char* worker_name,
                                                 TF_Status* status);

// it. This is accomplished by traversing the directory tree rooted at dirname
// and deleting entries as they are encountered.
//
// If dirname itself is not readable or does not exist, *undeleted_dir_count is
// set to 1, *undeleted_file_count is set to 0 and an appropriate status (e.g.
// TF_NOT_FOUND) is returned.
//
// If dirname and all its descendants were successfully deleted, TF_OK is

TF_CAPI_EXPORT extern void TF_ImportGraphDefOptionsRemapControlDependency(
    TF_ImportGraphDefOptions* opts, const char* src_name, TF_Operation* dst);

// Cause the imported graph to have a control dependency on `oper`. `oper`
// should exist in the graph being imported into.
TF_CAPI_EXPORT extern void TF_ImportGraphDefOptionsAddControlDependency(
    TF_ImportGraphDefOptions* opts, TF_Operation* oper);

namespace {

template <typename BackwardFunction, typename TapeTensor>
struct BackpropInitialState {
  OpTape<BackwardFunction, TapeTensor> op_tape;

  // Map from tensor ID to how many references still exist for this tensor in
  // the tape.
  std::unordered_map<int64_t, int64_t> tensor_usage_counts;

  // Maps from op ID to how many output tensors of this op still need to have
  // their gradients computed.

  /// Plugins:
  ///   * Must set `status` to `TF_OK` if rename was completed.
  ///   * Must set `status` to `TF_NOT_FOUND` if one of the parents entries in
  ///     either `src` or `dst` doesn't exist or if the specified `src` path
  ///     doesn't exist.
  ///   * Must set `status` to `TF_FAILED_PRECONDITION` if either `src` or
  ///     `dst` is a directory or if either of them is invalid.

               char* buffer, TF_Status* status);

  // Validate the given file signature with the existing file signature in the
  // cache. Returns true if the signature doesn't change or the file doesn't
  // exist before. If the signature changes, update the existing signature with
  // the new one and remove the file from cache.
  bool ValidateAndUpdateFileSignature(const std::string& filename,