code: public IpcLogEntry markStart() {
      if (registry != null) {
        inflightId = getInflightId();
        int n = logger.inflightRequests(inflightId).incrementAndGet();
        registry.distributionSummary(inflightId).record(n);
      }
  
      startTime = clock.wallTime();
      startNanos = clock.monotonicTime();
      return this;
    }
docs: Record the starting time for the request and update the number of inflight requests.
  This should be called just before starting the execution of the request. As soon as
  the request completes it is recommended to call {@link #markEnd()}.