public double getEstimate ( final byte [ ] key ) { if ( key == null ) { return Double . NaN ; } checkMethodKeySize ( key ) ; final double est = maps_ [ 0 ] . getEstimate ( key ) ; if ( est >= 0.0 ) { return est ; } //key has been promoted final int level = - ( int ) est ; final Map map = maps_ [ level ] ; return map . getEstimate ( key ) ; }
Retrieves the current estimate of unique count for a given key .