prysm-pulse/beacon-chain/attestation/service.go
2018-10-01 14:14:10 -05:00

110 lines
3.2 KiB
Go

// Package attestation defines the life-cycle and status of single and aggregated attestation.
package attestation
import (
"context"
"fmt"
"github.com/ethereum/go-ethereum/event"
"github.com/prysmaticlabs/prysm/beacon-chain/types"
"github.com/sirupsen/logrus"
)
var log = logrus.WithField("prefix", "attestation")
// Service represents a service that handles the internal
// logic of managing aggregated attestation.
type Service struct {
ctx context.Context
cancel context.CancelFunc
handler *Handler
broadcastFeed *event.Feed
broadcastChan chan *types.Attestation
incomingFeed *event.Feed
incomingChan chan *types.Attestation
}
// Config options for the service.
type Config struct {
Handler *Handler
ReceiveAttestationBuf int
BroadcastAttestationBuf int
}
// NewAttestService instantiates a new service instance that will
// be registered into a running beacon node.
func NewAttestService(ctx context.Context, cfg *Config) *Service {
ctx, cancel := context.WithCancel(ctx)
return &Service{
ctx: ctx,
cancel: cancel,
handler: cfg.Handler,
broadcastFeed: new(event.Feed),
broadcastChan: make(chan *types.Attestation, cfg.BroadcastAttestationBuf),
incomingFeed: new(event.Feed),
incomingChan: make(chan *types.Attestation, cfg.ReceiveAttestationBuf),
}
}
// Start an attestation service's main event loop.
func (a *Service) Start() {
log.Info("Starting service")
go a.aggregateAttestations()
}
// Stop the Attestation service's main event loop and associated goroutines.
func (a *Service) Stop() error {
defer a.cancel()
log.Info("Stopping service")
return nil
}
// IncomingAttestationFeed returns a feed that any service can send incoming p2p attestations into.
// The attestation service will subscribe to this feed in order to relay incoming attestations.
func (a *Service) IncomingAttestationFeed() *event.Feed {
return a.incomingFeed
}
// ContainsAttestation checks if an attestation has already been received and aggregated.
func (a *Service) ContainsAttestation(bitfield []byte, hash [32]byte) (bool, error) {
attestation, err := a.handler.getAttestation(hash)
if err != nil {
return false, fmt.Errorf("could not get attestation from DB: %v", err)
}
savedAttestationBitfield := attestation.AttesterBitfield()
for i := 0; i < len(bitfield); i++ {
if bitfield[i]&savedAttestationBitfield[i] != 0 {
return true, nil
}
}
return false, nil
}
// aggregateAttestations aggregates the newly broadcasted attestation that was
// received from sync service.
func (a *Service) aggregateAttestations() {
incomingSub := a.incomingFeed.Subscribe(a.incomingChan)
defer incomingSub.Unsubscribe()
for {
select {
case <-a.ctx.Done():
log.Debug("Attestation service context closed, exiting goroutine")
return
// Listen for a newly received incoming attestation from the sync service.
case attestation := <-a.incomingChan:
h, err := attestation.Hash()
if err != nil {
log.Errorf("Could not hash incoming attestation: %v", err)
continue
}
if err := a.handler.saveAttestation(attestation); err != nil {
log.Errorf("Could not save attestation: %v", err)
continue
}
log.Debugf("Forwarding aggregated attestation 0x%x to proposers through grpc", h)
}
}
}