int midIdx = (leftIdx + rightIdx) / 2;
GridGgfsFileAffinityRange midRange = ranges.get(midIdx);
if (midRange.belongs(blockOff))
return midRange.status() != RANGE_STATUS_MOVED ? midRange.affinityKey() :
includeMoved ? leftRange.affinityKey() : null;
// If offset is less then block start, update right index.
if (midRange.less(blockOff))
rightIdx = midIdx;