trait RedisPrefixTrait in Redis 8

trait RedisPrefixTrait {

  /**
   * @var string
   */
  protected $prefix;

  /**
   * Get global default prefix
   *
   * @param string $suffix
   *
   * @return string
   */
  protected function getDefaultPrefix($suffix = NULL) {
    $ret = NULL;
    if ($test_prefix = drupal_valid_test_ua()) {
      $ret = $test_prefix;
    }
    else {
      $prefixes = Settings::get('cache_prefix', '');
      if (is_string($prefixes)) {

        // Variable can be a string which then considered as a default
        // behavior.
        $ret = $prefixes;
      }
      else {
        if (NULL !== $suffix && isset($prefixes[$suffix])) {
          if (FALSE !== $prefixes[$suffix]) {

            // If entry is set and not false an explicit prefix is set
            // for the bin.
            $ret = $prefixes[$suffix];
          }
          else {

            // If we have an explicit false it means no prefix whatever
            // is the default configuration.
            $ret = '';
          }
        }
        else {

          // Key is not set, we can safely rely on default behavior.
          if (isset($prefixes['default']) && FALSE !== $prefixes['default']) {
            $ret = $prefixes['default'];
          }
          else {

            // When default is not set or an explicit false this means
            // no prefix.
            $ret = '';
          }
        }
      }
    }
    if (empty($ret)) {

      // If no prefix is given, use the same logic as core for APCu caching.
      $ret = Settings::getApcuPrefix('redis', DRUPAL_ROOT);
    }
    return $ret;
  }

  /**
   * Set prefix
   *
   * @param string $prefix
   */
  public function setPrefix($prefix) {
    $this->prefix = $prefix;
  }

  /**
   * Get prefix
   *
   * @return string
   */
  protected function getPrefix() {
    if (!isset($this->prefix)) {
      $this->prefix = $this
        ->getDefaultPrefix();
    }
    return $this->prefix;
  }

}