private long calculateHandlerUsageMsDiff() {
    long currentTime = EnvironmentEdgeManager.currentTime();
    long startTime = RpcServer.getCurrentCall().map(RpcCall::getStartTime).orElse(currentTime);
    long timeElapsed = currentTime - startTime;
    return handlerUsageTimeConsumed - timeElapsed;
  }
Update estimate quota(read/write size/capacityUnits) which will be consumed
@param scanRequest                     the scan to be executed
@param maxScannerResultSize            the maximum bytes to be returned by the scanner
@param maxBlockBytesScanned            the maximum bytes scanned in a single RPC call by the
                                       scanner
@param prevBlockBytesScannedDifference the difference between BBS of the previous two next
                                       calls
hbase-server/src/main/java/org/apache/hadoop/hbase/quotas/DefaultOperationQuota.java