Module polkadot_runtime_parachains::disputes::slashing

Dispute slashing pallet.

Once a dispute is concluded, we want to slash validators who were on the wrong side of the dispute. The slashing amount depends on whether the candidate was valid (none at the moment) or invalid (big). In addition to that, we might want to kick out the validators from the active set. Currently, we limit slashing to the backing group for invalid disputes.

The offences pallet from Substrate provides us with a way to do both. Currently, the interface expects us to provide staking information including nominator exposure in order to submit an offence.

Normally, we’d able to fetch this information from the runtime as soon as the dispute is concluded. This is also what im-online pallet does. However, since a dispute can conclude several sessions after the candidate was backed (see dispute_period in HostConfiguration), we can’t rely on this information being available in the context of the current block. The babe and grandpa equivocation handlers also have to deal with this problem.

Our implementation looks like a hybrid of im-online and grandpa equivocation handlers. Meaning, we submit an offence for the concluded disputes about the current session candidate directly from the runtime. If, however, the dispute is about a past session, we record unapplied slashes on chain, without FullIdentification of the offenders. Later on, a block producer can submit an unsigned transaction with KeyOwnershipProof of an offender and submit it to the runtime to produce an offence.

Re-exports

• pub use pallet::*;

Modules

• benchmarking
• pallet
  The pallet module in each FRAME pallet hosts the most important items needed to construct this pallet.

Structs

• BenchConfig
• SlashValidatorsForDisputes
  This type implements SlashingHandler.
• SlashingOffence
  An offence that is filed when a series of validators lost a dispute.
• SlashingReportHandler
  Actual HandleReports implementation.
• TestWeightInfo

Traits

• BenchmarkingConfiguration
  The benchmarking configuration.
• HandleReports
  A trait that defines methods to report an offence (after the slashing report has been validated) and for submitting a transaction to report a slash (from an offchain context).
• WeightInfo