prysm-pulse/shared/aggregation/attestations/attestations.go
terence tsao ee5d75732d
Add pkg crypto (#9603)
* Add pkg crypto

* Update go.yml

Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>
2021-09-15 22:55:11 +00:00

109 lines
3.7 KiB
Go

package attestations
import (
"github.com/pkg/errors"
"github.com/prysmaticlabs/prysm/config/features"
"github.com/prysmaticlabs/prysm/crypto/bls"
ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
"github.com/prysmaticlabs/prysm/shared/aggregation"
"github.com/sirupsen/logrus"
)
const (
// NaiveAggregation is an aggregation strategy without any optimizations.
NaiveAggregation AttestationAggregationStrategy = "naive"
// MaxCoverAggregation is a strategy based on Maximum Coverage greedy algorithm.
MaxCoverAggregation AttestationAggregationStrategy = "max_cover"
// OptMaxCoverAggregation is a strategy based on Maximum Coverage greedy algorithm.
// This new variant is optimized and relies on Bitlist64 (once fully tested, `max_cover`
// strategy will be replaced with this one).
OptMaxCoverAggregation AttestationAggregationStrategy = "opt_max_cover"
)
// AttestationAggregationStrategy defines attestation aggregation strategy.
type AttestationAggregationStrategy string
// attList represents list of attestations, defined for easier en masse operations (filtering, sorting).
type attList []*ethpb.Attestation
// BLS aggregate signature aliases for testing / benchmark substitution. These methods are
// significantly more expensive than the inner logic of AggregateAttestations so they must be
// substituted for benchmarks which analyze AggregateAttestations.
var aggregateSignatures = bls.AggregateSignatures
var signatureFromBytes = bls.SignatureFromBytes
var _ = logrus.WithField("prefix", "aggregation.attestations")
// ErrInvalidAttestationCount is returned when insufficient number
// of attestations is provided for aggregation.
var ErrInvalidAttestationCount = errors.New("invalid number of attestations")
// Aggregate aggregates attestations. The minimal number of attestations is returned.
// Aggregation occurs in-place i.e. contents of input array will be modified. Should you need to
// preserve input attestations, clone them before aggregating:
//
// clonedAtts := make([]*ethpb.Attestation, len(atts))
// for i, a := range atts {
// clonedAtts[i] = stateTrie.CopyAttestation(a)
// }
// aggregatedAtts, err := attaggregation.Aggregate(clonedAtts)
func Aggregate(atts []*ethpb.Attestation) ([]*ethpb.Attestation, error) {
strategy := AttestationAggregationStrategy(features.Get().AttestationAggregationStrategy)
switch strategy {
case "", NaiveAggregation:
return NaiveAttestationAggregation(atts)
case MaxCoverAggregation:
return MaxCoverAttestationAggregation(atts)
case OptMaxCoverAggregation:
return optMaxCoverAttestationAggregation(atts)
default:
return nil, errors.Wrapf(aggregation.ErrInvalidStrategy, "%q", strategy)
}
}
// AggregatePair aggregates pair of attestations a1 and a2 together.
func AggregatePair(a1, a2 *ethpb.Attestation) (*ethpb.Attestation, error) {
o, err := a1.AggregationBits.Overlaps(a2.AggregationBits)
if err != nil {
return nil, err
}
if o {
return nil, aggregation.ErrBitsOverlap
}
baseAtt := ethpb.CopyAttestation(a1)
newAtt := ethpb.CopyAttestation(a2)
if newAtt.AggregationBits.Count() > baseAtt.AggregationBits.Count() {
baseAtt, newAtt = newAtt, baseAtt
}
c, err := baseAtt.AggregationBits.Contains(newAtt.AggregationBits)
if err != nil {
return nil, err
}
if c {
return baseAtt, nil
}
newBits, err := baseAtt.AggregationBits.Or(newAtt.AggregationBits)
if err != nil {
return nil, err
}
newSig, err := signatureFromBytes(newAtt.Signature)
if err != nil {
return nil, err
}
baseSig, err := signatureFromBytes(baseAtt.Signature)
if err != nil {
return nil, err
}
aggregatedSig := aggregateSignatures([]bls.Signature{baseSig, newSig})
baseAtt.Signature = aggregatedSig.Marshal()
baseAtt.AggregationBits = newBits
return baseAtt, nil
}