address comment

Author: georgehao

eth/gasprice/feehistory.go

@@ -84,7 +84,7 @@ func (s sortGasAndReward) Less(i, j int) bool {
 // processBlock takes a blockFees structure with the blockNumber, the header and optionally
 // the block field filled in, retrieves the block from the backend if not present yet and
 // fills in the rest of the fields.
-func (oracle *Oracle) processBlock(bf *blockFees, percentiles []float64, headHeader *types.Header) {
+func (oracle *Oracle) processBlock(bf *blockFees, percentiles []float64, nonCongestedPrice *big.Int) {
 	chainconfig := oracle.backend.ChainConfig()
 	if bf.results.baseFee = bf.header.BaseFee; bf.results.baseFee == nil {
 		bf.results.baseFee = new(big.Int)
@@ -122,15 +122,8 @@ func (oracle *Oracle) processBlock(bf *blockFees, percentiles []float64, headHea
 	sorter := make(sortGasAndReward, len(bf.block.Transactions()))
 	for i, tx := range bf.block.Transactions() {
 		var reward *big.Int
-		pendingTxCount, _ := oracle.backend.StatsWithMinBaseFee(headHeader.BaseFee)
-		if pendingTxCount < oracle.congestedThreshold {
-			// Before Curie (EIP-1559), we need to return the total suggested gas price. After Curie we return defaultGasTipCap wei as the tip cap,
-			// as the base fee is set separately or added manually for legacy transactions.
-			price := oracle.defaultGasTipCap
-			if !oracle.backend.ChainConfig().IsCurie(headHeader.Number) {
-				price = oracle.defaultBasePrice
-			}
-			reward = price
+		if nonCongestedPrice != nil {
+			reward = nonCongestedPrice
 		} else {
 			reward, _ = tx.EffectiveGasTip(bf.block.BaseFee())
 		}
@@ -251,6 +244,20 @@ func (oracle *Oracle) FeeHistory(ctx context.Context, blocks int, unresolvedLast
 	}
 	oldestBlock := lastBlock + 1 - uint64(blocks)
 
+	// If pending txs are less than oracle.congestedThreshold, we consider the network to be non-congested and suggest
+	// a minimal tip cap. This is to prevent users from overpaying for gas when the network is not congested and a few
+	// high-priced txs are causing the suggested tip cap to be high.
+	var nonCongestedPrice *big.Int
+	pendingTxCount, _ := oracle.backend.StatsWithMinBaseFee(headHeader.BaseFee)
+	if pendingTxCount < oracle.congestedThreshold {
+		// Before Curie (EIP-1559), we need to return the total suggested gas price. After Curie we return defaultGasTipCap wei as the tip cap,
+		// as the base fee is set separately or added manually for legacy transactions.
+		nonCongestedPrice = oracle.defaultGasTipCap
+		if !oracle.backend.ChainConfig().IsCurie(headHeader.Number) {
+			nonCongestedPrice = oracle.defaultBasePrice
+		}
+	}
+
 	var (
 		next    = oldestBlock
 		results = make(chan *blockFees, blocks)
@@ -259,6 +266,7 @@ func (oracle *Oracle) FeeHistory(ctx context.Context, blocks int, unresolvedLast
 	for i, p := range rewardPercentiles {
 		binary.LittleEndian.PutUint64(percentileKey[i*8:(i+1)*8], math.Float64bits(p))
 	}
+
 	for i := 0; i < maxBlockFetchers && i < blocks; i++ {
 		go func() {
 			for {
@@ -272,7 +280,7 @@ func (oracle *Oracle) FeeHistory(ctx context.Context, blocks int, unresolvedLast
 				if pendingBlock != nil && blockNumber >= pendingBlock.NumberU64() {
 					fees.block, fees.receipts = pendingBlock, pendingReceipts
 					fees.header = fees.block.Header()
-					oracle.processBlock(fees, rewardPercentiles, headHeader)
+					oracle.processBlock(fees, rewardPercentiles, nonCongestedPrice)
 					results <- fees
 				} else {
 					cacheKey := struct {
@@ -294,7 +302,7 @@ func (oracle *Oracle) FeeHistory(ctx context.Context, blocks int, unresolvedLast
 							fees.header, fees.err = oracle.backend.HeaderByNumber(ctx, rpc.BlockNumber(blockNumber))
 						}
 						if fees.header != nil && fees.err == nil {
-							oracle.processBlock(fees, rewardPercentiles, headHeader)
+							oracle.processBlock(fees, rewardPercentiles, nonCongestedPrice)
 							if fees.err == nil {
 								oracle.historyCache.Add(cacheKey, fees.results)
 							}