prysm-pulse/beacon-chain/core/balances/rewards_penalties.go
2019-03-27 08:52:34 -07:00

424 lines
16 KiB
Go

// Package balances contains libraries to calculate reward and
// penalty quotients. It computes new validator balances
// for justifications, crosslinks and attestation inclusions. It
// also computes penalties for the inactive validators.
package balances
import (
"context"
"errors"
"fmt"
"github.com/prysmaticlabs/prysm/beacon-chain/core/epoch"
"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
"github.com/prysmaticlabs/prysm/shared/params"
"github.com/prysmaticlabs/prysm/shared/sliceutil"
"go.opencensus.io/trace"
)
// ExpectedFFGSource applies rewards or penalties
// for an expected FFG source. It uses total justified
// attesting balances, total validator balances and base
// reward quotient to calculate the reward amount.
// Validators who voted for previous justified hash
// will get a reward, everyone else will get a penalty.
//
// Spec pseudocode definition:
// Any validator index in previous_epoch_justified_attester_indices
// gains base_reward(state, index) * previous_epoch_justified_attesting_balance // total_balance.
// Any active validator v not in previous_epoch_justified_attester_indices
// loses base_reward(state, index).
func ExpectedFFGSource(
ctx context.Context,
state *pb.BeaconState,
justifiedAttesterIndices []uint64,
justifiedAttestingBalance uint64,
totalBalance uint64) *pb.BeaconState {
baseRewardQuotient := helpers.BaseRewardQuotient(totalBalance)
ctx, span := trace.StartSpan(ctx, "beacon-chain.ChainService.state.ProcessEpoch.ExpectedFFGSourceRewards")
defer span.End()
for _, index := range justifiedAttesterIndices {
state.ValidatorBalances[index] +=
helpers.BaseReward(state, index, baseRewardQuotient) *
justifiedAttestingBalance /
totalBalance
}
activeValidatorIndices := helpers.ActiveValidatorIndices(state.ValidatorRegistry, helpers.CurrentEpoch(state))
didNotAttestIndices := sliceutil.Not(justifiedAttesterIndices, activeValidatorIndices)
for _, index := range didNotAttestIndices {
state.ValidatorBalances[index] -=
helpers.BaseReward(state, index, baseRewardQuotient)
}
return state
}
// ExpectedFFGTarget applies rewards or penalties
// for an expected FFG target. It uses total boundary
// attesting balances, total validator balances and base
// reward quotient to calculate the reward amount.
// Validators who voted for epoch boundary block
// will get a reward, everyone else will get a penalty.
//
// Spec pseudocode definition:
// Any validator index in previous_epoch_boundary_attester_indices gains
// base_reward(state, index) * previous_epoch_boundary_attesting_balance // total_balance.
// Any active validator index not in previous_epoch_boundary_attester_indices loses
// base_reward(state, index).
func ExpectedFFGTarget(
ctx context.Context,
state *pb.BeaconState,
boundaryAttesterIndices []uint64,
boundaryAttestingBalance uint64,
totalBalance uint64) *pb.BeaconState {
ctx, span := trace.StartSpan(ctx, "beacon-chain.ChainService.state.ProcessEpoch.ExpectedFFGTargetRewards")
defer span.End()
baseRewardQuotient := helpers.BaseRewardQuotient(totalBalance)
for _, index := range boundaryAttesterIndices {
state.ValidatorBalances[index] +=
helpers.BaseReward(state, index, baseRewardQuotient) *
boundaryAttestingBalance /
totalBalance
}
activeValidatorIndices := helpers.ActiveValidatorIndices(state.ValidatorRegistry, helpers.CurrentEpoch(state))
didNotAttestIndices := sliceutil.Not(boundaryAttesterIndices, activeValidatorIndices)
for _, index := range didNotAttestIndices {
state.ValidatorBalances[index] -=
helpers.BaseReward(state, index, baseRewardQuotient)
}
return state
}
// ExpectedBeaconChainHead applies rewards or penalties
// for an expected beacon chain head. It uses total head
// attesting balances, total validator balances and base
// reward quotient to calculate the reward amount.
// Validators who voted for the canonical head block
// will get a reward, everyone else will get a penalty.
//
// Spec pseudocode definition:
// Any validator index in previous_epoch_head_attester_indices gains
// base_reward(state, index) * previous_epoch_head_attesting_balance // total_balance).
// Any active validator index not in previous_epoch_head_attester_indices loses
// base_reward(state, index).
func ExpectedBeaconChainHead(
ctx context.Context,
state *pb.BeaconState,
headAttesterIndices []uint64,
headAttestingBalance uint64,
totalBalance uint64) *pb.BeaconState {
ctx, span := trace.StartSpan(ctx, "beacon-chain.ChainService.state.ProcessEpoch.ExpectedBeaconChainHeadRewards")
defer span.End()
baseRewardQuotient := helpers.BaseRewardQuotient(totalBalance)
for _, index := range headAttesterIndices {
state.ValidatorBalances[index] +=
helpers.BaseReward(state, index, baseRewardQuotient) *
headAttestingBalance /
totalBalance
}
activeValidatorIndices := helpers.ActiveValidatorIndices(state.ValidatorRegistry, helpers.CurrentEpoch(state))
didNotAttestIndices := sliceutil.Not(headAttesterIndices, activeValidatorIndices)
for _, index := range didNotAttestIndices {
state.ValidatorBalances[index] -=
helpers.BaseReward(state, index, baseRewardQuotient)
}
return state
}
// InclusionDistance applies rewards based on
// inclusion distance. It uses calculated inclusion distance
// and base reward quotient to calculate the reward amount.
//
// Spec pseudocode definition:
// Any validator index in previous_epoch_attester_indices gains
// base_reward(state, index) * MIN_ATTESTATION_INCLUSION_DELAY //
// inclusion_distance(state, index)
func InclusionDistance(
ctx context.Context,
state *pb.BeaconState,
attesterIndices []uint64,
totalBalance uint64) (*pb.BeaconState, error) {
ctx, span := trace.StartSpan(ctx, "beacon-chain.ChainService.state.ProcessEpoch.ExpectedInclusionDistanceRewards")
defer span.End()
baseRewardQuotient := helpers.BaseRewardQuotient(totalBalance)
for _, index := range attesterIndices {
inclusionDistance, err := epoch.InclusionDistance(state, index)
if err != nil {
return nil, fmt.Errorf("could not get inclusion distance: %v", err)
}
if inclusionDistance == 0 {
return nil, errors.New("could not process inclusion distance: 0")
}
state.ValidatorBalances[index] +=
helpers.BaseReward(state, index, baseRewardQuotient) *
params.BeaconConfig().MinAttestationInclusionDelay /
inclusionDistance
}
return state, nil
}
// InactivityFFGSource applies penalties to inactive
// validators that missed to vote FFG source over an
// extended of time. (epochs_since_finality > 4)
//
// Spec pseudocode definition:
// Any active validator index not in previous_epoch_justified_attester_indices,
// loses inactivity_penalty(state, index, epochs_since_finality)
func InactivityFFGSource(
ctx context.Context,
state *pb.BeaconState,
justifiedAttesterIndices []uint64,
totalBalance uint64,
epochsSinceFinality uint64) *pb.BeaconState {
ctx, span := trace.StartSpan(ctx, "beacon-chain.ChainService.state.ProcessEpoch.InactivityFFGSourcePenalties")
defer span.End()
baseRewardQuotient := helpers.BaseRewardQuotient(totalBalance)
activeValidatorIndices := helpers.ActiveValidatorIndices(state.ValidatorRegistry, helpers.CurrentEpoch(state))
didNotAttestIndices := sliceutil.Not(justifiedAttesterIndices, activeValidatorIndices)
for _, index := range didNotAttestIndices {
state.ValidatorBalances[index] -=
helpers.InactivityPenalty(state, index, baseRewardQuotient, epochsSinceFinality)
}
return state
}
// InactivityFFGTarget applies penalties to inactive
// validators that missed to vote FFG target over an
// extended of time. (epochs_since_finality > 4)
//
// Spec pseudocode definition:
// Any active validator index not in previous_epoch_boundary_attester_indices,
// loses inactivity_penalty(state, index, epochs_since_finality)
func InactivityFFGTarget(
ctx context.Context,
state *pb.BeaconState,
boundaryAttesterIndices []uint64,
totalBalance uint64,
epochsSinceFinality uint64) *pb.BeaconState {
ctx, span := trace.StartSpan(ctx, "beacon-chain.ChainService.state.ProcessEpoch.InactivityFFGTargetPenalties")
defer span.End()
baseRewardQuotient := helpers.BaseRewardQuotient(totalBalance)
activeValidatorIndices := helpers.ActiveValidatorIndices(state.ValidatorRegistry, helpers.CurrentEpoch(state))
didNotAttestIndices := sliceutil.Not(boundaryAttesterIndices, activeValidatorIndices)
for _, index := range didNotAttestIndices {
state.ValidatorBalances[index] -=
helpers.InactivityPenalty(state, index, baseRewardQuotient, epochsSinceFinality)
}
return state
}
// InactivityChainHead applies penalties to inactive validators
// that missed to vote on canonical head over an extended of time.
// (epochs_since_finality > 4)
//
// Spec pseudocode definition:
// Any active validator index not in previous_epoch_head_attester_indices,
// loses base_reward(state, index)
func InactivityChainHead(
ctx context.Context,
state *pb.BeaconState,
headAttesterIndices []uint64,
totalBalance uint64) *pb.BeaconState {
ctx, span := trace.StartSpan(ctx, "beacon-chain.ChainService.state.ProcessEpoch.InactivityChainHeadPenalties")
defer span.End()
baseRewardQuotient := helpers.BaseRewardQuotient(totalBalance)
activeValidatorIndices := helpers.ActiveValidatorIndices(state.ValidatorRegistry, helpers.CurrentEpoch(state))
didNotAttestIndices := sliceutil.Not(headAttesterIndices, activeValidatorIndices)
for _, index := range didNotAttestIndices {
state.ValidatorBalances[index] -=
helpers.BaseReward(state, index, baseRewardQuotient)
}
return state
}
// InactivityExitedPenalties applies additional (2x) penalties
// to inactive validators with status EXITED_WITH_PENALTY.
//
// Spec pseudocode definition:
// Any active_validator index with validator.slashed_epoch <= current_epoch,
// loses 2 * inactivity_penalty(state, index, epochs_since_finality) +
// base_reward(state, index).
func InactivityExitedPenalties(
ctx context.Context,
state *pb.BeaconState,
totalBalance uint64,
epochsSinceFinality uint64) *pb.BeaconState {
ctx, span := trace.StartSpan(ctx, "beacon-chain.ChainService.state.ProcessEpoch.InactivityExitedPenalties")
defer span.End()
baseRewardQuotient := helpers.BaseRewardQuotient(totalBalance)
currentEpoch := helpers.CurrentEpoch(state)
activeValidatorIndices := helpers.ActiveValidatorIndices(state.ValidatorRegistry, currentEpoch)
for _, index := range activeValidatorIndices {
if state.ValidatorRegistry[index].SlashedEpoch <= currentEpoch {
state.ValidatorBalances[index] -=
2*helpers.InactivityPenalty(state, index, baseRewardQuotient, epochsSinceFinality) +
helpers.BaseReward(state, index, baseRewardQuotient)
}
}
return state
}
// InactivityInclusionDistance applies penalties in relation with
// inclusion delay to inactive validators.
//
// Spec pseudocode definition:
// Any validator index in previous_epoch_attester_indices loses
// base_reward(state, index) - base_reward(state, index) *
// MIN_ATTESTATION_INCLUSION_DELAY // inclusion_distance(state, index)
func InactivityInclusionDistance(
ctx context.Context,
state *pb.BeaconState,
attesterIndices []uint64,
totalBalance uint64) (*pb.BeaconState, error) {
ctx, span := trace.StartSpan(ctx, "beacon-chain.ChainService.state.ProcessEpoch.InactivityInclusionDistancePenalties")
defer span.End()
baseRewardQuotient := helpers.BaseRewardQuotient(totalBalance)
for _, index := range attesterIndices {
inclusionDistance, err := epoch.InclusionDistance(state, index)
if err != nil {
return nil, fmt.Errorf("could not get inclusion distance: %v", err)
}
baseReward := helpers.BaseReward(state, index, baseRewardQuotient)
state.ValidatorBalances[index] -= baseReward -
baseReward*params.BeaconConfig().MinAttestationInclusionDelay/
inclusionDistance
}
return state, nil
}
// AttestationInclusion awards the the beacon
// proposers who included previous epoch attestations.
//
// Spec pseudocode definition:
// For each index in previous_epoch_attester_indices,
// we determine the proposer proposer_index =
// get_beacon_proposer_index(state, inclusion_slot(state, index))
// and set state.validator_balances[proposer_index] +=
// base_reward(state, index) // ATTESTATION_INCLUSION_REWARD_QUOTIENT
func AttestationInclusion(
ctx context.Context,
state *pb.BeaconState,
totalBalance uint64,
prevEpochAttesterIndices []uint64) (*pb.BeaconState, error) {
ctx, span := trace.StartSpan(ctx, "beacon-chain.ChainService.state.ProcessEpoch.AttestationInclusion")
defer span.End()
baseRewardQuotient := helpers.BaseRewardQuotient(totalBalance)
for _, index := range prevEpochAttesterIndices {
slot, err := epoch.InclusionSlot(state, index)
if err != nil {
return nil, fmt.Errorf("could not get inclusion slot: %v", err)
}
proposerIndex, err := helpers.BeaconProposerIndex(state, slot)
if err != nil {
return nil, fmt.Errorf("could not get propoer index: %v", err)
}
state.ValidatorBalances[proposerIndex] +=
helpers.BaseReward(state, proposerIndex, baseRewardQuotient) /
params.BeaconConfig().AttestationInclusionRewardQuotient
}
return state, nil
}
// Crosslinks awards or slashs attesters
// for attesting shard cross links.
//
// Spec pseudocode definition:
// For slot in range(get_epoch_start_slot(previous_epoch), get_epoch_start_slot(current_epoch)),
// let crosslink_committees_at_slot = get_crosslink_committees_at_slot(slot).
// For every (crosslink_committee, shard) in crosslink_committee_at_slot,
// and every index in crosslink_committee:
// If index in attesting_validators(crosslink_committee),
// state.validator_balances[index] += base_reward(state, index) *
// total_attesting_balance(crosslink_committee) //
// get_total_balance(state, crosslink_committee)).
// If index not in attesting_validators(crosslink_committee),
// state.validator_balances[index] -= base_reward(state, index).
func Crosslinks(
ctx context.Context,
state *pb.BeaconState,
thisEpochAttestations []*pb.PendingAttestation,
prevEpochAttestations []*pb.PendingAttestation) (*pb.BeaconState, error) {
ctx, span := trace.StartSpan(ctx, "beacon-chain.ChainService.state.ProcessEpoch.CrosslinkBalances")
defer span.End()
prevEpoch := helpers.PrevEpoch(state)
currentEpoch := helpers.CurrentEpoch(state)
startSlot := helpers.StartSlot(prevEpoch)
endSlot := helpers.StartSlot(currentEpoch)
for i := startSlot; i < endSlot; i++ {
// RegistryChange is a no-op when requesting slot in current and previous epoch.
// Process crosslinks rewards will never request crosslink committees of next epoch.
crosslinkCommittees, err := helpers.CrosslinkCommitteesAtSlot(state, i, false /* registryChange */)
if err != nil {
return nil, fmt.Errorf("could not get shard committees for slot %d: %v",
i-params.BeaconConfig().GenesisSlot, err)
}
for _, crosslinkCommittee := range crosslinkCommittees {
shard := crosslinkCommittee.Shard
committee := crosslinkCommittee.Committee
totalAttestingBalance, err :=
epoch.TotalAttestingBalance(ctx, state, shard, thisEpochAttestations, prevEpochAttestations)
if err != nil {
return nil,
fmt.Errorf("could not get attesting balance for shard committee %d: %v", shard, err)
}
totalBalance := epoch.TotalBalance(ctx, state, committee)
baseRewardQuotient := helpers.BaseRewardQuotient(totalBalance)
attestingIndices, err := epoch.AttestingValidators(
ctx,
state,
shard,
thisEpochAttestations,
prevEpochAttestations)
if err != nil {
return nil,
fmt.Errorf("could not get attesting indices for shard committee %d: %v", shard, err)
}
for _, index := range committee {
baseReward := helpers.BaseReward(state, index, baseRewardQuotient)
if sliceutil.IsIn(index, attestingIndices) {
state.ValidatorBalances[index] +=
baseReward * totalAttestingBalance / totalBalance
} else {
state.ValidatorBalances[index] -= baseReward
}
}
}
}
return state, nil
}