get token ring for batch accumulation

token.go

func (t *tokenRing) GetIndexForPartitionKey(partitionKey []byte) int {
    if t == nil {
        return 0
    }

    hash := t.partitioner.Hash(partitionKey)
    l := len(t.tokens)
    // no host tokens, no available hosts
    if l == 0 {
        return 0
    }
    // find the primary replica
    ringIndex := sort.Search(
        l,
        func(i int) bool {
            return !t.tokens[i].Less(hash)
        },
    )

    if ringIndex == l {
        // wrap around to the first in the ring
        ringIndex = 0
    }
    return ringIndex
}