Safeguard efficiency score calculation

consensus/blake3pow/consensus.go

@@ -361,7 +361,10 @@ func (blake3pow *Blake3pow) verifyHeader(chain consensus.ChainHeaderReader, head
 				return fmt.Errorf("invalid threshold count: have %v, want %v", header.ThresholdCount(), 0)
 			}
 		} else {
-			expectedEfficiencyScore := chain.ComputeEfficiencyScore(parent)
+			expectedEfficiencyScore, err := chain.ComputeEfficiencyScore(parent)
+			if err != nil {
+				return err
+			}
 			if header.EfficiencyScore() != expectedEfficiencyScore {
 				return fmt.Errorf("invalid efficiency score: have %v, want %v", header.EfficiencyScore(), expectedEfficiencyScore)
 			}

consensus/consensus.go

@@ -93,7 +93,7 @@ type ChainHeaderReader interface {
 	ProcessingState() bool
 
 	// ComputeEfficiencyScore returns the efficiency score computed at each prime block
-	ComputeEfficiencyScore(header *types.WorkObject) uint16
+	ComputeEfficiencyScore(header *types.WorkObject) (uint16, error)
 
 	// ComputeExpansionNumber returns the expansion number of the block
 	ComputeExpansionNumber(parent *types.WorkObject) (uint8, error)

consensus/progpow/consensus.go

@@ -357,7 +357,10 @@ func (progpow *Progpow) verifyHeader(chain consensus.ChainHeaderReader, header,
 				return fmt.Errorf("invalid threshold count: have %v, want %v", header.ThresholdCount(), 0)
 			}
 		} else {
-			expectedEfficiencyScore := chain.ComputeEfficiencyScore(parent)
+			expectedEfficiencyScore, err := chain.ComputeEfficiencyScore(parent)
+			if err != nil {
+				return err
+			}
 			if header.EfficiencyScore() != expectedEfficiencyScore {
 				return fmt.Errorf("invalid efficiency score: have %v, want %v", header.EfficiencyScore(), expectedEfficiencyScore)
 			}

core/core.go

@@ -998,7 +998,7 @@ func (c *Core) SubscribeChainSideEvent(ch chan<- ChainSideEvent) event.Subscript
 // ComputeEfficiencyScore computes the efficiency score for the given prime
 // block This data is is only valid if called from Prime context, otherwise
 // there is no guarantee for this data to be accurate
-func (c *Core) ComputeEfficiencyScore(header *types.WorkObject) uint16 {
+func (c *Core) ComputeEfficiencyScore(header *types.WorkObject) (uint16, error) {
 	return c.sl.hc.ComputeEfficiencyScore(header)
 }
 

core/headerchain.go

@@ -35,6 +35,10 @@ const (
 	c_calcOrderCacheLimit = 10000
 )
 
+var (
+	errInvalidEfficiencyScore = errors.New("unable to compute efficiency score")
+)
+
 type calcOrderResponse struct {
 	intrinsicEntropy *big.Int
 	order            int
@@ -1225,17 +1229,21 @@ func (hc *HeaderChain) ComputeExpansionNumber(parent *types.WorkObject) (uint8,
 }
 
 // ComputeEfficiencyScore calculates the efficiency score for the given header
-func (hc *HeaderChain) ComputeEfficiencyScore(parent *types.WorkObject) uint16 {
+func (hc *HeaderChain) ComputeEfficiencyScore(parent *types.WorkObject) (uint16, error) {
 	deltaEntropy := new(big.Int).Add(parent.ParentDeltaEntropy(common.REGION_CTX), parent.ParentDeltaEntropy(common.ZONE_CTX))
 	uncledDeltaEntropy := new(big.Int).Add(parent.ParentUncledDeltaEntropy(common.REGION_CTX), parent.ParentUncledDeltaEntropy(common.ZONE_CTX))
 
 	// Take the ratio of deltaEntropy to the uncledDeltaEntropy in percentage
 	efficiencyScore := uncledDeltaEntropy.Mul(uncledDeltaEntropy, big.NewInt(100))
+	if deltaEntropy.Cmp(common.Big0) == 0 {
+		hc.logger.Error(errInvalidEfficiencyScore)
+		return 0, errInvalidEfficiencyScore
+	}
 	efficiencyScore.Div(efficiencyScore, deltaEntropy)
 
 	// Calculate the exponential moving average
 	ewma := (uint16(efficiencyScore.Uint64()) + parent.EfficiencyScore()*params.TREE_EXPANSION_FILTER_ALPHA) / 10
-	return ewma
+	return ewma, nil
 }
 
 // UpdateEtxEligibleSlices returns the updated etx eligible slices field

core/worker.go

@@ -1461,7 +1461,10 @@ func (w *worker) prepareWork(genParams *generateParams, wo *types.WorkObject) (*
 			newWo.Header().SetThresholdCount(0)
 		} else {
 			// compute the efficiency score at each prime block
-			efficiencyScore := w.hc.ComputeEfficiencyScore(parent)
+			efficiencyScore, err := w.hc.ComputeEfficiencyScore(parent)
+			if err != nil {
+				return nil, err
+			}
 			newWo.Header().SetEfficiencyScore(efficiencyScore)
 
 			// If the threshold count is zero we have not started considering for the

quai/api_backend.go

@@ -629,7 +629,7 @@ func (b *QuaiAPIBackend) IsBlockHashABadHash(hash common.Hash) bool {
 	return b.quai.core.IsBlockHashABadHash(hash)
 }
 
-func (b *QuaiAPIBackend) ComputeEfficiencyScore(header *types.WorkObject) uint16 {
+func (b *QuaiAPIBackend) ComputeEfficiencyScore(header *types.WorkObject) (uint16, error) {
 	return b.quai.core.ComputeEfficiencyScore(header)
 }