Enable dPoS

pkg/protocol/engine/consensus/blockgadget/thresholdblockgadget/confirmation_ratification.go

@@ -51,7 +51,7 @@ func (g *Gadget) trackConfirmationRatifierWeight(votingBlock *blocks.Block) {
 
 func (g *Gadget) shouldConfirm(block *blocks.Block) bool {
 	blockSeats := len(block.ConfirmationRatifiers())
-	totalCommitteeSeats := g.seatManager.SeatCount()
+	totalCommitteeSeats := g.seatManager.SeatCountInSlot(block.ID().Slot())
 
 	return votes.IsThresholdReached(blockSeats, totalCommitteeSeats, g.optsConfirmationThreshold)
 }

pkg/protocol/engine/consensus/blockgadget/thresholdblockgadget/witness_weight.go

@@ -87,7 +87,7 @@ func (g *Gadget) TrackWitnessWeight(votingBlock *blocks.Block) {
 }
 
 func (g *Gadget) shouldPreAcceptAndPreConfirm(block *blocks.Block) (preAccept bool, preConfirm bool) {
-	committeeTotalSeats := g.seatManager.SeatCount()
+	committeeTotalSeats := g.seatManager.SeatCountInSlot(block.ID().Slot())
 	blockSeats := len(block.Witnesses())
 
 	onlineCommitteeTotalSeats := g.seatManager.OnlineCommittee().Size()

pkg/protocol/engine/consensus/slotgadget/totalweightslotgadget/gadget.go

@@ -120,9 +120,9 @@ func (g *Gadget) trackVotes(block *blocks.Block) {
 }
 
 func (g *Gadget) refreshSlotFinalization(tracker *slottracker.SlotTracker, previousLatestSlotIndex iotago.SlotIndex, newLatestSlotIndex iotago.SlotIndex) (finalizedSlots []iotago.SlotIndex) {
-	committeeTotalSeats := g.seatManager.SeatCount()
 
 	for i := lo.Max(g.lastFinalizedSlot, previousLatestSlotIndex) + 1; i <= newLatestSlotIndex; i++ {
+		committeeTotalSeats := g.seatManager.SeatCountInSlot(i)
 		attestorsTotalSeats := len(tracker.Voters(i))
 
 		if !votes.IsThresholdReached(attestorsTotalSeats, committeeTotalSeats, g.optsSlotFinalizationThreshold) {

pkg/protocol/engine/upgrade/signalingupgradeorchestrator/orchestrator.go

@@ -263,7 +263,7 @@ func (o *Orchestrator) tryUpgrade(currentEpoch iotago.EpochIndex, lastSlotInEpoc
 	}
 
 	// Check whether the threshold for version was reached.
-	totalSeatCount := o.seatManager.SeatCount()
+	totalSeatCount := o.seatManager.SeatCountInEpoch(currentEpoch)
 	if !votes.IsThresholdReached(mostSupporters, totalSeatCount, votes.SuperMajority) {
 		return
 	}

pkg/protocol/sybilprotection/seatmanager/mock/mockseatmanager.go

@@ -159,7 +159,10 @@ func (m *ManualPOA) OnlineCommittee() ds.Set[account.SeatIndex] {
 	return m.online
 }
 
-func (m *ManualPOA) SeatCount() int {
+func (m *ManualPOA) SeatCountInSlot(_ iotago.SlotIndex) int {
+	return m.committee.SeatCount()
+}
+func (m *ManualPOA) SeatCountInEpoch(_ iotago.EpochIndex) int {
 	return m.committee.SeatCount()
 }
 

pkg/protocol/sybilprotection/seatmanager/poa/poa.go

@@ -146,7 +146,14 @@ func (s *SeatManager) OnlineCommittee() ds.Set[account.SeatIndex] {
 	return s.activityTracker.OnlineCommittee()
 }
 
-func (s *SeatManager) SeatCount() int {
+func (s *SeatManager) SeatCountInSlot(_ iotago.SlotIndex) int {
+	s.committeeMutex.RLock()
+	defer s.committeeMutex.RUnlock()
+
+	return s.committee.SeatCount()
+}
+
+func (s *SeatManager) SeatCountInEpoch(_ iotago.EpochIndex) int {
 	s.committeeMutex.RLock()
 	defer s.committeeMutex.RUnlock()
 
@@ -166,9 +173,11 @@ func (s *SeatManager) InitializeCommittee(epoch iotago.EpochIndex, activityTime
 		return ierrors.Wrapf(err, "failed to load PoA committee for epoch %d", epoch)
 	}
 
-	s.committee = committeeAccounts.SelectCommittee(committeeAccounts.IDs()...)
+	committeeAccountsIDs := committeeAccounts.IDs()
+	s.committee = committeeAccounts.SelectCommittee(committeeAccountsIDs...)
 
-	onlineValidators := committeeAccounts.IDs()
+	// Set validators that are part of the committee as active.
+	onlineValidators := committeeAccountsIDs
 	if len(s.optsOnlineCommitteeStartup) > 0 {
 		onlineValidators = s.optsOnlineCommitteeStartup
 	}

pkg/protocol/sybilprotection/seatmanager/seatmanager.go

@@ -33,7 +33,9 @@ type SeatManager interface {
 	OnlineCommittee() ds.Set[account.SeatIndex]
 
 	// SeatCount returns the number of seats in the SeatManager.
-	SeatCount() int
+	SeatCountInSlot(slot iotago.SlotIndex) int
+
+	SeatCountInEpoch(epoch iotago.EpochIndex) int
 
 	// Interface embeds the required methods of the module.Interface.
 	module.Interface

pkg/protocol/sybilprotection/seatmanager/topstakers/options.go

@@ -19,9 +19,3 @@ func WithOnlineCommitteeStartup(optsOnlineCommittee ...iotago.AccountID) options
 		p.optsOnlineCommitteeStartup = optsOnlineCommittee
 	}
 }
-
-func WithSeatCount(optsSeatCount uint32) options.Option[SeatManager] {
-	return func(p *SeatManager) {
-		p.optsSeatCount = optsSeatCount
-	}
-}

pkg/protocol/sybilprotection/seatmanager/topstakers/topstakers.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/iotaledger/hive.go/ds"
 	"github.com/iotaledger/hive.go/ierrors"
+	"github.com/iotaledger/hive.go/lo"
 	"github.com/iotaledger/hive.go/runtime/module"
 	"github.com/iotaledger/hive.go/runtime/options"
 	"github.com/iotaledger/hive.go/runtime/syncutils"
@@ -30,7 +31,6 @@ type SeatManager struct {
 	committeeMutex  syncutils.RWMutex
 	activityTracker activitytracker.ActivityTracker
 
-	optsSeatCount              uint32
 	optsActivityWindow         time.Duration
 	optsOnlineCommitteeStartup []iotago.AccountID
 
@@ -85,42 +85,21 @@ func (s *SeatManager) RotateCommittee(epoch iotago.EpochIndex, candidates accoun
 	s.committeeMutex.Lock()
 	defer s.committeeMutex.Unlock()
 
-	// If there are fewer candidates than required for epoch 0, then the previous committee cannot be copied.
-	if len(candidates) < s.SeatCount() && epoch == 0 {
-		return nil, ierrors.Errorf("at least %d candidates are required for committee in epoch 0, got %d", s.SeatCount(), len(candidates))
+	if len(candidates) == 0 {
+		return nil, ierrors.New("candidates must not be empty")
 	}
 
-	// If there are fewer candidates than required, then re-use the previous committee.
-	if len(candidates) < s.SeatCount() {
-		// TODO: what if staking period of a committee member ends in the next epoch?
-		committee, exists := s.committeeInEpoch(epoch - 1)
-		if !exists {
-			return nil, ierrors.Errorf("cannot re-use previous committee from epoch %d as it does not exist", epoch-1)
-		}
-
-		accounts, err := committee.Accounts()
-		if err != nil {
-			return nil, ierrors.Wrapf(err, "error while getting accounts from committee for epoch %d", epoch-1)
-		}
-
-		if err := s.committeeStore.Store(epoch, accounts); err != nil {
-			return nil, ierrors.Wrapf(err, "error while storing committee for epoch %d", epoch)
-		}
-
-		return committee, nil
-	}
-
-	committee, err := s.selectNewCommittee(candidates)
+	committee, err := s.selectNewCommittee(epoch, candidates)
 	if err != nil {
 		return nil, ierrors.Wrap(err, "error while selecting new committee")
 	}
 
-	accounts, err := committee.Accounts()
+	committeeAccounts, err := committee.Accounts()
 	if err != nil {
-		return nil, ierrors.Wrapf(err, "error while getting accounts for newly selected committee for epoch %d", epoch)
+		return nil, ierrors.Wrapf(err, "error while getting committeeAccounts for newly selected committee for epoch %d", epoch)
 	}
 
-	if err := s.committeeStore.Store(epoch, accounts); err != nil {
+	if err := s.committeeStore.Store(epoch, committeeAccounts); err != nil {
 		return nil, ierrors.Wrapf(err, "error while storing committee for epoch %d", epoch)
 	}
 
@@ -161,8 +140,22 @@ func (s *SeatManager) OnlineCommittee() ds.Set[account.SeatIndex] {
 	return s.activityTracker.OnlineCommittee()
 }
 
-func (s *SeatManager) SeatCount() int {
-	return int(s.optsSeatCount)
+func (s *SeatManager) SeatCountInSlot(slot iotago.SlotIndex) int {
+	epoch := s.apiProvider.APIForSlot(slot).TimeProvider().EpochFromSlot(slot)
+
+	return s.SeatCountInEpoch(epoch)
+}
+
+func (s *SeatManager) SeatCountInEpoch(epoch iotago.EpochIndex) int {
+	s.committeeMutex.RLock()
+	defer s.committeeMutex.RUnlock()
+
+	// TODO: this function is a hot path as it is called for every single block. Maybe accessing the storage is too slow.
+	if committee, exists := s.committeeInEpoch(epoch); exists {
+		return committee.SeatCount()
+	}
+
+	return int(s.apiProvider.APIForEpoch(epoch).ProtocolParameters().TargetCommitteeSize())
 }
 
 func (s *SeatManager) Shutdown() {
@@ -202,8 +195,8 @@ func (s *SeatManager) SetCommittee(epoch iotago.EpochIndex, validators *account.
 	s.committeeMutex.Lock()
 	defer s.committeeMutex.Unlock()
 
-	if validators.Size() != int(s.optsSeatCount) {
-		return ierrors.Errorf("invalid number of validators: %d, expected: %d", validators.Size(), s.optsSeatCount)
+	if validators.Size() == 0 {
+		return ierrors.New("committee must not be empty")
 	}
 
 	err := s.committeeStore.Store(epoch, validators)
@@ -214,7 +207,7 @@ func (s *SeatManager) SetCommittee(epoch iotago.EpochIndex, validators *account.
 	return nil
 }
 
-func (s *SeatManager) selectNewCommittee(candidates accounts.AccountsData) (*account.SeatedAccounts, error) {
+func (s *SeatManager) selectNewCommittee(epoch iotago.EpochIndex, candidates accounts.AccountsData) (*account.SeatedAccounts, error) {
 	sort.Slice(candidates, func(i int, j int) bool {
 		// Prioritize the candidate that has a larger pool stake.
 		if candidates[i].ValidatorStake+candidates[i].DelegationStake != candidates[j].ValidatorStake+candidates[j].DelegationStake {
@@ -240,10 +233,14 @@ func (s *SeatManager) selectNewCommittee(candidates accounts.AccountsData) (*acc
 		return bytes.Compare(candidates[i].ID[:], candidates[j].ID[:]) > 0
 	})
 
+	// We try to select up to targetCommitteeSize candidates to be part of the committee. If there are fewer candidates
+	// than required, then we select all of them and the committee size will be smaller than targetCommitteeSize.
+	committeeSize := lo.Min(len(candidates), int(s.apiProvider.APIForEpoch(epoch).ProtocolParameters().TargetCommitteeSize()))
+
 	// Create new Accounts instance that only included validators selected to be part of the committee.
 	newCommitteeAccounts := account.NewAccounts()
 
-	for _, candidateData := range candidates[:s.optsSeatCount] {
+	for _, candidateData := range candidates[:committeeSize] {
 		if err := newCommitteeAccounts.Set(candidateData.ID, &account.Pool{
 			PoolStake:      candidateData.ValidatorStake + candidateData.DelegationStake,
 			ValidatorStake: candidateData.ValidatorStake,