mirror of
https://gitlab.com/pulsechaincom/prysm-pulse.git
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300 lines
11 KiB
Go
300 lines
11 KiB
Go
package beacon
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import (
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"bytes"
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"context"
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"io"
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"math"
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"time"
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"github.com/golang/protobuf/ptypes"
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"github.com/golang/protobuf/ptypes/empty"
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pb "github.com/prysmaticlabs/prysm/proto/beacon/rpc/v1"
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"github.com/prysmaticlabs/prysm/shared/event"
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"github.com/prysmaticlabs/prysm/validator/params"
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"github.com/prysmaticlabs/prysm/validator/utils"
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"github.com/sirupsen/logrus"
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)
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var log = logrus.WithField("prefix", "beacon")
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type rpcClientService interface {
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BeaconServiceClient() pb.BeaconServiceClient
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}
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// Service that interacts with a beacon node via RPC.
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type Service struct {
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ctx context.Context
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cancel context.CancelFunc
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pubKey []byte
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rpcClient rpcClientService
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assignedSlot uint64
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shardID uint64
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role pb.ValidatorRole
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attesterAssignmentFeed *event.Feed
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proposerAssignmentFeed *event.Feed
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processedAttestationFeed *event.Feed
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genesisTimestamp time.Time
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slotAlignmentDuration time.Duration
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}
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// NewBeaconValidator instantiates a service that interacts with a beacon node
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// via gRPC requests.
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func NewBeaconValidator(ctx context.Context, pubKey []byte, rpcClient rpcClientService) *Service {
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ctx, cancel := context.WithCancel(ctx)
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return &Service{
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ctx: ctx,
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pubKey: pubKey,
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cancel: cancel,
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rpcClient: rpcClient,
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attesterAssignmentFeed: new(event.Feed),
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proposerAssignmentFeed: new(event.Feed),
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processedAttestationFeed: new(event.Feed),
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slotAlignmentDuration: time.Duration(params.DefaultConfig().SlotDuration) * time.Second,
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}
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}
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// Start the main routine for a beacon client service.
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func (s *Service) Start() {
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log.Info("Starting service")
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beaconServiceClient := s.rpcClient.BeaconServiceClient()
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// First thing the validator does is request the current validator assignments
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// for the current beacon node cycle as well as the genesis timestamp
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// from the beacon node. From here, a validator can keep an internal
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// ticker that starts at the current slot the beacon node is in. This current slot
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// value is determined by taking the time differential between the genesis block
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// time and the current system time.
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//
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// Note: this does not validate the current system time against a global
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// NTP server, which will be important to do in production.
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// currently in a cycle we are supposed to participate in.
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s.fetchCurrentAssignmentsAndGenesisTime(beaconServiceClient)
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// Then, we kick off a routine that uses the begins a ticker based on the beacon node's
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// genesis timestamp and the validator will use this slot ticker to
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// determine when it is assigned to perform proposals or attestations.
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//
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// We block until the current time is a multiple of params.SlotDuration
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// so the validator and beacon node's internal tickers are aligned.
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utils.BlockingWait(s.slotAlignmentDuration)
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// We kick off a routine that listens for stream of validator assignment coming from
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// beacon node. This will update validator client on which slot, shard ID and what
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// responsbility to perform.
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go s.listenForAssignmentChange(beaconServiceClient)
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slotTicker := time.NewTicker(s.slotAlignmentDuration)
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go s.waitForAssignment(slotTicker.C, beaconServiceClient)
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go s.listenForProcessedAttestations(beaconServiceClient)
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}
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// Stop the main loop.
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func (s *Service) Stop() error {
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defer s.cancel()
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log.Info("Stopping service")
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return nil
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}
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// fetchCurrentAssignmentsAndGenesisTime fetches both the genesis timestamp as well
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// as the current assignments for the current cycle in the beacon node. This allows
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// the validator to do the following:
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//
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// (1) determine if it should act as an attester/proposer, at what slot,
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// and what shard
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//
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// (2) determine the seconds since genesis by using the latest crystallized
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// state recalc, then determine how many seconds have passed between that time
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// and the current system time.
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//
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// From this, the validator client can deduce what slot interval the beacon
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// node is in and determine when exactly it is time to propose or attest.
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func (s *Service) fetchCurrentAssignmentsAndGenesisTime(client pb.BeaconServiceClient) {
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// Currently fetches assignments for all validators.
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req := &pb.ValidatorAssignmentRequest{
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AllValidators: true,
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}
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res, err := client.CurrentAssignmentsAndGenesisTime(s.ctx, req)
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if err != nil {
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// If this RPC request fails, the entire system should fatal as it is critical for
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// the validator to begin this way.
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log.Fatalf("could not fetch genesis time and latest canonical state from beacon node: %v", err)
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}
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// Determine what slot the beacon node is in by checking the number of seconds
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// since the genesis block.
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genesisTimestamp, err := ptypes.Timestamp(res.GetGenesisTimestamp())
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if err != nil {
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log.Fatalf("cannot compute genesis timestamp: %v", err)
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}
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log.Infof("Setting validator genesis time to %s", genesisTimestamp.Format(time.UnixDate))
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s.genesisTimestamp = genesisTimestamp
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for _, assign := range res.Assignments {
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if bytes.Equal(assign.PublicKey.PublicKey, s.pubKey) {
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s.role = assign.Role
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// + 1 to account for the genesis block being slot 0.
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s.assignedSlot = s.CurrentCycleStartSlot(params.DemoConfig().CycleLength) + assign.AssignedSlot + 1
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s.shardID = assign.ShardId
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log.Infof("Validator shuffled. Pub key 0x%s re-assigned to shard ID %d for %v duty at slot %d",
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string(s.pubKey),
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s.shardID,
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s.role,
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s.assignedSlot)
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}
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}
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}
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// listenForAssignmentChange listens for validator assignment changes via a RPC stream.
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// when there's an assignment change, beacon service will update its shard ID, slot number and role.
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func (s *Service) listenForAssignmentChange(client pb.BeaconServiceClient) {
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req := &pb.ValidatorAssignmentRequest{PublicKeys: []*pb.PublicKey{{PublicKey: s.pubKey}}}
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stream, err := client.ValidatorAssignments(s.ctx, req)
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if err != nil {
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log.Errorf("could not fetch validator assigned slot and responsibility from beacon node: %v", err)
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return
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}
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for {
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assignment, err := stream.Recv()
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// If the stream is closed, we stop the loop.
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if err == io.EOF {
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break
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}
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// If context is canceled we stop the loop.
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if s.ctx.Err() != nil {
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log.Debugf("Context has been canceled so shutting down the loop: %v", s.ctx.Err())
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break
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}
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if err != nil {
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log.Errorf("Could not receive latest validator assignment from stream: %v", err)
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break
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}
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for _, assign := range assignment.Assignments {
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if bytes.Equal(assign.PublicKey.PublicKey, s.pubKey) {
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s.role = assign.Role
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if s.CurrentCycleStartSlot(params.DemoConfig().CycleLength) == 0 {
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// +1 to account for genesis block being slot 0.
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s.assignedSlot = params.DemoConfig().CycleLength + assign.AssignedSlot + 1
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} else {
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s.assignedSlot = s.CurrentCycleStartSlot(params.DemoConfig().CycleLength) + assign.AssignedSlot + 1
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}
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s.shardID = assign.ShardId
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log.Infof("Validator with pub key 0x%s re-assigned to shard ID %d for %v duty at slot %d",
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string(s.pubKey),
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s.shardID,
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s.role,
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s.assignedSlot)
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}
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}
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}
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}
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// waitForAssignment waits till it's validator's role to attest or propose. Then it forwards
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// the canonical block to the proposer service or attester service to process.
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func (s *Service) waitForAssignment(ticker <-chan time.Time, client pb.BeaconServiceClient) {
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for {
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select {
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case <-s.ctx.Done():
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return
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case <-ticker:
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currentSlot := s.CurrentBeaconSlot()
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log.Infof("role: %v, assigned slot: %d, current slot: %d", s.role, s.assignedSlot, currentSlot)
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if s.role == pb.ValidatorRole_ATTESTER && s.assignedSlot == currentSlot {
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log.WithField("slotNumber", s.CurrentBeaconSlot()).Info("Assigned attest slot number reached")
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block, err := client.CanonicalHead(s.ctx, &empty.Empty{})
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if err != nil {
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log.Errorf("Could not fetch canonical head via gRPC from beacon node: %v", err)
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continue
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}
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// We forward the latest canonical block to the attester service a feed.
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s.attesterAssignmentFeed.Send(block)
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} else if s.role == pb.ValidatorRole_PROPOSER && s.assignedSlot == currentSlot {
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log.WithField("slotNumber", s.CurrentBeaconSlot()).Info("Assigned proposal slot number reached")
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block, err := client.CanonicalHead(s.ctx, &empty.Empty{})
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if err != nil {
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log.Errorf("Could not fetch canonical head via gRPC from beacon node: %v", err)
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continue
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}
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// We forward the latest canonical block to the proposer service a feed.
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s.proposerAssignmentFeed.Send(block)
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}
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}
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}
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}
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// listenForProcessedAttestations receives processed attestations from the
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// the beacon node's RPC server via gRPC streams.
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func (s *Service) listenForProcessedAttestations(client pb.BeaconServiceClient) {
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stream, err := client.LatestAttestation(s.ctx, &empty.Empty{})
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if err != nil {
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log.Errorf("Could not setup beacon chain attestation streaming client: %v", err)
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return
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}
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for {
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attestation, err := stream.Recv()
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// If the stream is closed, we stop the loop.
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if err == io.EOF {
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break
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}
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// If context is canceled we stop the loop.
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if s.ctx.Err() != nil {
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log.Debugf("Context has been canceled so shutting down the loop: %v", s.ctx.Err())
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break
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}
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if err != nil {
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log.Errorf("Could not receive latest attestation from stream: %v", err)
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continue
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}
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log.WithField("slotNumber", attestation.GetSlot()).Info("Latest attestation slot number")
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s.processedAttestationFeed.Send(attestation)
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}
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}
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// AttesterAssignmentFeed returns a feed that is written to whenever it is the validator's
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// slot to perform attestations.
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func (s *Service) AttesterAssignmentFeed() *event.Feed {
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return s.attesterAssignmentFeed
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}
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// ProposerAssignmentFeed returns a feed that is written to whenever it is the validator's
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// slot to proposer blocks.
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func (s *Service) ProposerAssignmentFeed() *event.Feed {
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return s.proposerAssignmentFeed
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}
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// ProcessedAttestationFeed returns a feed that is written to whenever an attestation
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// is processed by a beacon node.
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func (s *Service) ProcessedAttestationFeed() *event.Feed {
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return s.processedAttestationFeed
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}
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// PublicKey returns validator's public key.
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func (s *Service) PublicKey() []byte {
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return s.pubKey
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}
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// CurrentBeaconSlot based on the genesis timestamp of the protocol.
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func (s *Service) CurrentBeaconSlot() uint64 {
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secondsSinceGenesis := time.Since(s.genesisTimestamp).Seconds()
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if secondsSinceGenesis-params.DefaultConfig().SlotDuration < 0 {
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return 0
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}
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return uint64(math.Floor(secondsSinceGenesis/params.DefaultConfig().SlotDuration)) - 1
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}
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// CurrentCycleStartSlot returns the slot at which the current cycle started.
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func (s *Service) CurrentCycleStartSlot(cycleLength uint64) uint64 {
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currentSlot := s.CurrentBeaconSlot()
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cycleNum := currentSlot / cycleLength
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return uint64(cycleNum) * cycleLength
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}
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