Multiste Purge Transients Per Site

I have a bit of a complex scenario, I want to create a function to purge all transients for a single site within a multisite install using object-cache backend and HHVM.

Currently I am able to do a cachedump to list all keys and then clear the keys as needed following Scott Taylors method here – https://scotty-t.com/2012/01/20/wordpress-memcached/

$memcache = new Memcache();
$memcache->connect( $server, '11211' );
$list = array();
$allSlabs = $memcache->getExtendedStats( 'slabs' );
$items = $memcache->getExtendedStats( 'items' );
foreach ( $allSlabs as $server => $slabs ) {
    foreach( $slabs as $slabId => $slabMeta ) {
        $cdump = $memcache->getExtendedStats( 'cachedump', (int) $slabId );
        foreach( $cdump as $keys => $arrVal ) {
            if ( !is_array( $arrVal ) ) continue;
            foreach( $arrVal as $k => $v ) {
                $list[] = $k;
            }
        }
    }
}

Here is the catch, in HHVM cachedump has been removed, ref – https://docs.hhvm.com/manual/en/memcache.getextendedstats.php

Does anyone have any idea how to “Purge Transients Per Site” any other way?

I feel like there is something I am missing, any advice?