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iotaledger / iri

IOTA Reference Implementation
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Add aboveMinDepth() check to improve tip selection game theory #842

Open qriptau opened 6 years ago

qriptau commented 6 years ago

Description

Add aboveMinDepth() check in WalkValidatorImpl.java to disincentivise blowballs around most recent milestones

Motivation

Currently nodes (for example the one spamming 'TYPPI') have an incentive to use lowest depth when selecting tips. It improves their own confirmation rate but, particularly while they are still using IRI 1.4.2.4, hurts the overall network rate. In order to reward spammers for using higher depth, i am proposing the inclusion of an aboveMinDepth() function that checks to make sure at least one of the two tips a tx confirms indirectly references a milestone older than milestone.latestSolidSubtangleMilestoneIndex - minDepth. If both tips confirm only recent milestones it should be ignored and the random walk should continue on a different path

Requirements

Addition of function aboveMinDepth() in WalkValidatorImpl.java.

Open Questions

Is there any incentive to not choose a minimum depth in the current implementation?

Am I planning to do it myself with a PR?

No, not sure best way to implement if ok change

qriptau commented 6 years ago

btw i still think belowMaxDepth() should be removed ;)