presto-main/src/main/java/io/prestosql/operator/aggregation/histogram/ValueStore.java/ValueStore/ValueStore
class ValueStore:    @VisibleForTesting
    public ValueStore(int expectedSize, BlockBuilder values)
    {
        bucketCount = computeBucketCount(expectedSize, MAX_FILL_RATIO);
        mask = bucketCount - 1;
        maxFill = calculateMaxFill(bucketCount, MAX_FILL_RATIO);
        this.values = values;
        buckets = new IntBigArray(-1);
        buckets.ensureCapacity(bucketCount);
        valueHashes = new LongBigArray(-1);
        valueHashes.ensureCapacity(bucketCount);
    }