} else {
			$this->site_id = get_current_blog_id();
		}

		$this->role_key = $wpdb->get_blog_prefix( $this->site_id ) . 'user_roles';

		if ( ! empty( $this->roles ) && ! $this->use_db ) {
			return;
		}

		$this->roles = $this->get_roles_data();

		$this->init_roles();
	}

	/**
	 * Gets the ID of the site for which roles are currently initialized.
	 *
	 * @since 4.9.0
	 *
	 * @return int Site ID.
	 */
	public function get_site_id() {
		return $this->site_id;
	}

	/**
	 * Gets the available roles data.
	 *
	 * @since 4.9.0
	 *
	 * @global array $wp_user_roles Used to set the 'roles' property value.
	 *
	 * @return array Roles array.
	 */
	protected function get_roles_data() {
		global $wp_user_roles;

		if ( ! empty( $wp_user_roles ) ) {
			return $wp_user_roles;
		}

		if ( is_multisite() && get_current_blog_id() !== $this->site_id ) {
			remove_action( 'switch_blog', 'wp_switch_roles_and_user', 1 );

			$roles = get_blog_option( $this->site_id, $this->role_key, array() );

			add_action( 'switch_blog', 'wp_switch_roles_and_user', 1, 2 );

			return $roles;
		}

		return get_option( $this->role_key, array() );
	}
}