[Lucene - Improve the BSearch Performance] Add two conditions to improve the performance of Binary Search

[Fuxiang Chen]

Dear Lucene Developers,

In the source file "SortedIntDocSet.java", the code fragment that is used
for binary search can have its speed improved by adding two more conditions.

Original Code
--------------------
        if (docb < doca) {
          low = mid+1;
        }
        else if (docb > doca) {
          high = mid-1;
        }


Changed Code
----------------------
        if (docb < doca) {
          low = mid+1;
        }
        else if (docb > doca) {
          high = mid-1;
        else if (low != mid)     //Equal but range is not fully scanned
          high = mid; //Set upper bound to current number and rescan
        else //Equal and full range is scanned
          return mid;

Reference: http://stackoverflow.com/questions/6676360/


-- 
Warmest Regards,
    Fuxiang