code: function(dirname, keydir, dataFile, cb1) {
    var fileId = Number(path.basename(dataFile, '.medea.data'));
    var file = new DataFileParser({ filename: dataFile });
    file.on('error', cb1);
    file.on('entry', function(entry) {
      var key = entry.key.toString();
  
      if (key.length === 0) {
        return;
      }
  
      if (!keydir.has(key) || (keydir.has(key) && keydir.get(key).fileId === fileId)) {
        var kEntry = new KeyDirEntry();
        kEntry.key = key;
        kEntry.fileId = fileId;
        kEntry.timestamp = entry.timestamp;
        kEntry.valueSize = entry.valueSize;
        kEntry.valuePosition = entry.valuePosition;
        keydir.set(key, kEntry);
      }
    });
    file.on('end', cb1);
    file.parse();
  }
docs: parse data file for keys when hint file is missing