les/vflux/server: fix priority cornercase causing fuzzer timeout #22650
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…ereum#22650) * les/vflux/server: fix estimatePriority corner case * les/vflux/server: simplify inactiveAllowance == 0 case
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This PR fixes a cornercase that caused two nodes kicking each other out of the priority pool in an infinite loop when the connection bias was very low. There was an earlier attempted fix for this case that tried to ensure that
estimatePriorityalways returns a smaller priority thanpriorityfor the same node at the same moment. This was ensured by subtracting 1 fromestimatePriorityresult. However, the negative balanceExpiredValuecan change its exponent and lose some precision when adding the bias and in some rare cases this could create a situation when the future priority estimate still wasn't smaller than the current priority. Now the same condition is enforced directly.A second commit simplifies a
ClientPoolcondition whenInactiveAllowanceis zero. With the current design there is no need to handle this case separately and increase the risk of creating faulty cornercases in the future. This change is unrelated to the issue detected by the fuzzer, I just realized it during testing but I think it could be in this PR because it is a simple change.