feat: miner minimum gas price

cmd/geth/main.go

@@ -19,6 +19,7 @@ package main
 
 import (
 	"fmt"
+	"math/big"
 	"os"
 	"sort"
 	"strconv"
@@ -428,6 +429,18 @@ func startNode(ctx *cli.Context, stack *node.Node, backend ethapi.Backend, isCon
 		}()
 	}
 
+	// CHANGE(MXC)
+	gasprice := flags.GlobalBig(ctx, utils.MinerGasPriceFlag.Name)
+	if gasprice.Cmp(big.NewInt(0)) > 0 {
+		ethBackend, ok := backend.(*eth.EthAPIBackend)
+		if !ok {
+			utils.Fatalf("Ethereum service not running")
+		}
+		// Set the gas price to the limits from the CLI and start mining
+		gasprice := flags.GlobalBig(ctx, utils.MinerGasPriceFlag.Name)
+		ethBackend.TxPool().SetGasPrice(gasprice)
+	}
+
 	// Start auxiliary services if enabled
 	if ctx.Bool(utils.MiningEnabledFlag.Name) || ctx.Bool(utils.DeveloperFlag.Name) {
 		// Mining only makes sense if a full Ethereum node is running

core/txpool/txpool.go

@@ -695,6 +695,13 @@ func (pool *TxPool) add(tx *types.Transaction, local bool) (replaced bool, err e
 	// the sender is marked as local previously, treat it as the local transaction.
 	isLocal := local || pool.locals.containsTx(tx)
 
+	// CHANGE(MXC): check if the transaction gas price is less than the minimum gas price
+	if tx.GasPrice().Cmp(pool.gasPrice) < 0 {
+		log.Trace("Discarding underpriced transaction", "hash", hash, "gasPrice", tx.GasPrice(), "local", isLocal)
+		underpricedTxMeter.Mark(1)
+		return false, ErrUnderpriced
+	}
+
 	// If the transaction fails basic validation, discard it
 	if err := pool.validateTx(tx, isLocal); err != nil {
 		log.Trace("Discarding invalid transaction", "hash", hash, "err", err)