@Override
    public String toString() {
      return "RowLockContext{" + "row=" + row + ", readWriteLock=" + readWriteLock + ", count="
        + count + ", threadName=" + threadName + '}';
    }
Get an exclusive ( write lock ) lock on a given row.
@param row Which row to lock.
@return A locked RowLock. The lock is exclusive and already aqquired.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java