presto-main/src/main/java/io/prestosql/operator/PartitionedLookupSource.java/PartitionedLookupSource/OuterPositionTracker
class PartitionedLookupSource:        private OuterPositionTracker(boolean[][] visitedPositions, AtomicBoolean finished, AtomicLong referenceCount)
        {
            this.visitedPositions = visitedPositions;
            this.finished = finished;
            this.referenceCount = referenceCount;
        }