From 5fed6e63c522255458fac1a40b53065411328a7f Mon Sep 17 00:00:00 2001
From: charliec <charliec@zetachain.com>
Date: Wed, 9 Aug 2023 15:37:43 -0500
Subject: [PATCH] use dynamic gas price for Ethereum chains

---
 common/chain.go          |  9 ++++++++-
 zetaclient/evm_signer.go | 42 +++++++++++++++++++++++++++++++---------
 2 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/common/chain.go b/common/chain.go
index 3c395b540b..f8509cb702 100644
--- a/common/chain.go
+++ b/common/chain.go
@@ -2,10 +2,11 @@ package common
 
 import (
 	"fmt"
+	"strings"
+
 	"github.com/btcsuite/btcd/chaincfg"
 	"github.com/btcsuite/btcutil"
 	ethcommon "github.com/ethereum/go-ethereum/common"
-	"strings"
 )
 
 var (
@@ -94,6 +95,12 @@ func IsBitcoinChain(chainID int64) bool {
 		chainID == 8332 // mainnet
 }
 
+func IsEthereumChain(chainID int64) bool {
+	return chainID == 1 || // eth mainnet
+		chainID == 5 || // Goerli
+		chainID == 1337 // eth privnet
+}
+
 // IsEmpty is to determinate whether the chain is empty
 func (chain Chain) IsEmpty() bool {
 	return strings.TrimSpace(chain.String()) == ""
diff --git a/zetaclient/evm_signer.go b/zetaclient/evm_signer.go
index 7a7028b2fc..6242c94c00 100644
--- a/zetaclient/evm_signer.go
+++ b/zetaclient/evm_signer.go
@@ -5,6 +5,12 @@ import (
 	"encoding/base64"
 	"encoding/hex"
 	"fmt"
+	"math/big"
+	"math/rand"
+	"strconv"
+	"strings"
+	"time"
+
 	"github.com/ethereum/go-ethereum/accounts/abi"
 	ethcommon "github.com/ethereum/go-ethereum/common"
 	ethtypes "github.com/ethereum/go-ethereum/core/types"
@@ -15,11 +21,6 @@ import (
 	"github.com/zeta-chain/zetacore/common"
 	"github.com/zeta-chain/zetacore/x/crosschain/types"
 	zetaObserverModuleTypes "github.com/zeta-chain/zetacore/x/observer/types"
-	"math/big"
-	"math/rand"
-	"strconv"
-	"strings"
-	"time"
 )
 
 type EVMSigner struct {
@@ -285,10 +286,23 @@ func (signer *EVMSigner) TryProcessOutTx(send *types.CrossChainTx, outTxMan *Out
 	}
 	var sendhash [32]byte
 	copy(sendhash[:32], sendHash[:32])
-	gasprice, ok := new(big.Int).SetString(send.GetCurrentOutTxParam().OutboundTxGasPrice, 10)
-	if !ok {
-		logger.Error().Err(err).Msgf("cannot convert gas price  %s ", send.GetCurrentOutTxParam().OutboundTxGasPrice)
-		return
+
+	// use dynamic gas price for ethereum chains
+	var gasprice *big.Int
+	if common.IsEthereumChain(toChain.ChainId) {
+		suggested, err := signer.client.SuggestGasPrice(context.Background())
+		if err != nil {
+			logger.Error().Err(err).Msgf("cannot get gas price from chain %s ", toChain)
+			return
+		}
+		gasprice = roundUpToNearestGwei(suggested)
+	} else {
+		specified, ok := new(big.Int).SetString(send.GetCurrentOutTxParam().OutboundTxGasPrice, 10)
+		if !ok {
+			logger.Error().Err(err).Msgf("cannot convert gas price  %s ", send.GetCurrentOutTxParam().OutboundTxGasPrice)
+			return
+		}
+		gasprice = specified
 	}
 
 	var tx *ethtypes.Transaction
@@ -423,3 +437,13 @@ func (signer *EVMSigner) SignWhitelistTx(action string, recipient ethcommon.Addr
 
 	return tx, nil
 }
+
+func roundUpToNearestGwei(gasPrice *big.Int) *big.Int {
+	oneGwei := big.NewInt(1_000_000_000) // 1 Gwei
+	mod := new(big.Int)
+	mod.Mod(gasPrice, oneGwei)
+	if mod.Cmp(big.NewInt(0)) == 0 { // gasprice is already a multiple of 1 Gwei
+		return gasPrice
+	}
+	return new(big.Int).Add(gasPrice, new(big.Int).Sub(oneGwei, mod))
+}