Lock is evil.
This will actually affect the accuracy of GetDelta because
inboundDelta and outboundDelta may be calculated based on
the data collected at different time (eg. UpdateOutbound
get called before Interlocked.Read(ref _outbound)).
But that's not a problem. We can tolerate this little
inaccuracy. Besides, the _inbound, _outbound, _lastInbound
and _lastOutbound will be totally good because we use Interlocked.
noisyfox
0266ad9d59