TF_Status* status);

// Retrieves the next item from the given TF_StringStream and places a pointer
// to it in *result. If no more items are in the list, *result is set to NULL
// and false is returned.
//
// Ownership of the items retrieved with this function remains with the library.
// Item points are invalidated after a call to TF_StringStreamDone.

TF_CAPI_EXPORT extern void TF_GetNodesToPreserveList(
    const TF_GrapplerItem* item, char** values, size_t* lengths, int num_values,
    void* storage, size_t storage_size, TF_Status* status);

// Get a set of node names for fetch nodes. Fills in `values` and `lengths`,
// they will be used in `TF_GetFetchNodesList`
TF_CAPI_EXPORT extern void TF_GetFetchNodesListSize(const TF_GrapplerItem* item,
                                                    int* num_values,

#include "absl/synchronization/mutex.h"
#include "tensorflow/c/env.h"
#include "tensorflow/c/tf_status.h"

namespace tf_gcs_filesystem {

/// \brief An LRU cache of string keys and arbitrary values, with configurable
/// max item age (in seconds) and max entries.
///
/// This class is thread safe.
template <typename T>
class ExpiringLRUCache {
 public:
  /// A `max_age` of 0 means that nothing is cached. A `max_entries` of 0 means

  Status Init(
      const tensorflow::RewriterConfig_CustomGraphOptimizer* config) override {
    return OkStatus();
  }
  Status Optimize(Cluster* cluster, const GrapplerItem& item,
                  GraphDef* optimized_graph_def) override;

  ~CGraphOptimizer() override {
    if (optimizer_.destroy_func != nullptr) {
      (*optimizer_.destroy_func)(c_optimizer_);
    }
  }

 private:

typedef enum TF_Filesystem_Option_Type {
  TF_Filesystem_Option_Type_Int = 0,
  TF_Filesystem_Option_Type_Real,
  TF_Filesystem_Option_Type_Buffer,
  TF_Filesystem_Num_Option_Types,  // must always be the last item
} TF_Filesystem_Option_Type;

typedef struct TF_Filesystem_Option {
  char* name;                         // null terminated, owned
  char* description;                  // null terminated, owned