@Override
  public long incMemStoreSize(long dataSizeDelta, long heapSizeDelta, long offHeapSizeDelta,
    int cellsCountDelta) {
    this.offHeapSize.addAndGet(offHeapSizeDelta);
    this.heapSize.addAndGet(heapSizeDelta);
    this.cellsCount.addAndGet(cellsCountDelta);
    return this.dataSize.addAndGet(dataSizeDelta);
  }
Accounting of current heap and data sizes. Thread-safe. Many threads can do updates against this
single instance.
@see NonThreadSafeMemStoreSizing
@see MemStoreSize
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/ThreadSafeMemStoreSizing.java