code: void initialize() {
          Preconditions.checkState(this.database.get() == null, "%s has already been initialized.", this.logId);
  
          try {
              clear(true);
              this.database.set(openDatabase());
          } catch (Exception ex) {
              // Make sure we cleanup anything we may have created in case of failure.
              try {
                  close();
              } catch (Exception closeEx) {
                  ex.addSuppressed(closeEx);
              }
  
              throw ex;
          }
  
          log.info("{}: Initialized.", this.logId);
      }
docs: Initializes this instance of the RocksDB cache. This method must be invoked before the cache can be used.