Feat: trigger acceptance only after the winning state has been attested

pkg/core/acceptance/state.go

@@ -8,9 +8,6 @@ const (
 	// Pending is the state of pending spenders.
 	Pending State = iota
 
-	// PreAccepted is the state of pre-accepted spenders.
-	PreAccepted
-
 	// Accepted is the state of accepted spenders.
 	Accepted
 

pkg/core/weight/value.go

@@ -13,6 +13,9 @@ type Value struct {
 	// validatorsWeight is the second tier which tracks weight in a non-cumulative manner (BFT style).
 	validatorsWeight int64
 
+	// attestorsWeight is the third tier which tracks weight in a non-cumulative manner (BFT style).
+	attestorsWeight int64
+
 	// acceptanceState is the final tier which determines the decision of the spender.
 	acceptanceState acceptance.State
 }
@@ -55,6 +58,18 @@ func (v Value) SetValidatorsWeight(weight int64) Value {
 	return v
 }
 
+// AttestorsWeight returns the weight of the validators.
+func (v Value) AttestorsWeight() int64 {
+	return v.attestorsWeight
+}
+
+// SetAttestorsWeight sets the  weight of the attestors and returns the new Value.
+func (v Value) SetAttestorsWeight(weight int64) Value {
+	v.attestorsWeight = weight
+
+	return v
+}
+
 // AcceptanceState returns the acceptance state of the Value.
 func (v Value) AcceptanceState() acceptance.State {
 	return v.acceptanceState

pkg/core/weight/weight.go

@@ -17,6 +17,9 @@ type Weight struct {
 	// Voters is the set of voters contributing to the weight
 	Voters ds.Set[account.SeatIndex]
 
+	// Attestors is the set of attestors contributing to the weight.
+	Attestors ds.Set[account.SeatIndex]
+
 	// value is the current weight Value.
 	value Value
 
@@ -27,8 +30,9 @@ type Weight struct {
 // New creates a new Weight instance.
 func New() *Weight {
 	w := &Weight{
-		Voters:   ds.NewSet[account.SeatIndex](),
-		OnUpdate: event.New1[Value](),
+		Voters:    ds.NewSet[account.SeatIndex](),
+		Attestors: ds.NewSet[account.SeatIndex](),
+		OnUpdate:  event.New1[Value](),
 	}
 
 	return w
@@ -103,6 +107,41 @@ func (w *Weight) DeleteVoter(seat account.SeatIndex) *Weight {
 	return w
 }
 
+// AddAttestor adds the given voter to the list of Attestors, updates the weight and returns the Weight (for chaining).
+func (w *Weight) AddAttestor(seat account.SeatIndex) *Weight {
+	if added := w.Attestors.Add(seat); added {
+		if newValue, valueUpdated := w.updateAttestorsWeight(); valueUpdated {
+			w.OnUpdate.Trigger(newValue)
+		}
+	}
+
+	return w
+}
+
+// DeleteAttestor removes the given voter from the list of Attestors, updates the weight and returns the Weight (for chaining).
+func (w *Weight) DeleteAttestor(seat account.SeatIndex) *Weight {
+	if deleted := w.Attestors.Delete(seat); deleted {
+		if newValue, valueUpdated := w.updateAttestorsWeight(); valueUpdated {
+			w.OnUpdate.Trigger(newValue)
+		}
+	}
+
+	return w
+}
+
+// ResetAttestors removes all voters from the list of Attestors, updates the weight and returns the Weight (for chaining).
+func (w *Weight) ResetAttestors() *Weight {
+	if w.Attestors.Size() >= 1 {
+		w.Attestors.Clear()
+
+		if newValue, valueUpdated := w.updateAttestorsWeight(); valueUpdated {
+			w.OnUpdate.Trigger(newValue)
+		}
+	}
+
+	return w
+}
+
 func (w *Weight) updateValidatorsWeight() (Value, bool) {
 	w.mutex.Lock()
 	defer w.mutex.Unlock()
@@ -117,6 +156,20 @@ func (w *Weight) updateValidatorsWeight() (Value, bool) {
 	return w.value, false
 }
 
+func (w *Weight) updateAttestorsWeight() (Value, bool) {
+	w.mutex.Lock()
+	defer w.mutex.Unlock()
+
+	newAttestorsWeight := int64(w.Attestors.Size())
+	if w.value.AttestorsWeight() != newAttestorsWeight {
+		w.value = w.value.SetAttestorsWeight(newAttestorsWeight)
+
+		return w.value, true
+	}
+
+	return w.value, false
+}
+
 // AcceptanceState returns the acceptance state of the weight.
 func (w *Weight) AcceptanceState() acceptance.State {
 	w.mutex.RLock()

pkg/protocol/engine/mempool/spenddag/spenddagv1/spender.go

@@ -113,7 +113,7 @@ func NewSpender[SpenderID, ResourceID spenddag.IDType, VoteRank spenddag.VoteRan
 	c.preferredInstead = c
 
 	c.unhookAcceptanceMonitoring = c.Weight.OnUpdate.Hook(func(value weight.Value) {
-		if value.AcceptanceState().IsPending() && value.ValidatorsWeight() >= c.acceptanceThreshold() {
+		if value.AcceptanceState().IsPending() && value.ValidatorsWeight() >= c.acceptanceThreshold() && value.AttestorsWeight() >= c.acceptanceThreshold() {
 			c.setAcceptanceState(acceptance.Accepted)
 		}
 	}).Unhook
@@ -219,6 +219,17 @@ func (c *Spender[SpenderID, ResourceID, VoteRank]) ApplyVote(vote *vote.Vote[Vot
 	// update the latest vote
 	c.LatestVotes.Set(vote.Voter, vote)
 
+	// track attestors when we reach the acceptance threshold
+	if c.Weight.Value().ValidatorsWeight() > c.acceptanceThreshold() {
+		if vote.IsLiked() {
+			c.Weight.AddAttestor(vote.Voter)
+		} else {
+			c.Weight.DeleteAttestor(vote.Voter)
+		}
+	} else {
+		c.Weight.ResetAttestors()
+	}
+
 	// abort if the vote does not change the opinion of the validator
 	if exists && latestVote.IsLiked() == vote.IsLiked() {
 		return