We want to increase our throughput for downtime estimation. This commit
adds the ability to reach out to multiple nodes concurrently for downtime
estimation. The number of concurrent routines is determined by a new config
flag, EstimationConcurrencyLimit. It also increases the default
EstimationBatchSize to 1000.
Change-Id: I800ce7ec1035885afa194c3c3f64eedd4f6f61eb
more trustworthy downtime tracking
Detection chore: Do not update downtime at all from the detection chore.
We only want to include downtime between two explicitly failed ping attempts
(the duration between last contact success and the first failed ping is no longer
included in downtime calculation)
Estimation chore: If the satellite started after the last failed ping for a node,
do not include offline time since the last failed ping time - only
estimate based on two failed pings with no satellite downtime in
between.
This protects us from including satellite downtime in our storagenode downtime calculations.
Change-Id: I1fddc9f7255a7023e02474255d70c64faae75b8a
