uint64_t Length(const TF_ReadOnlyMemoryRegion* region);
}  // namespace tf_read_only_memory_region

namespace tf_gcs_filesystem {
typedef struct GcsFileStat {
  TF_FileStatistics base;
  int64_t generation_number;
} GcsFileStat;

typedef struct GCSFile {
  google::cloud::storage::Client gcs_client;  // owned
  bool compose;
  absl::Mutex block_cache_lock;

    int64_t read = 0;
    if (is_cache_enabled) {
      absl::ReaderMutexLock l(&gcs_file->block_cache_lock);
      GcsFileStat stat;
      gcs_file->stat_cache->LookupOrCompute(
          path, &stat,
          [gcs_file, bucket, object](const std::string& path, GcsFileStat* stat,
                                     TF_Status* status) {
            UncachedStatForObject(bucket, object, stat, &gcs_file->gcs_client,