Add FixedFeeMultiplier to rfq fee pricer (#1782)

* Feat: apply fixed fee multiplier

* Feat: add TestGetTotalFeeWithMultiplier

services/rfq/relayer/pricer/fee_pricer.go

@@ -118,8 +118,10 @@ func (f *feePricer) getFee(ctx context.Context, gasChain, denomChain uint32, gas
 	feeUSDC := new(big.Float).Mul(feeUSD, new(big.Float).SetFloat64(denomTokenPrice))
 	// Note that this rounds towards zero- we may need to apply rounding here if
 	// we want to be conservative and lean towards overestimating fees.
-	feeUSDCDecimals, _ := new(big.Float).Mul(feeUSDC, new(big.Float).SetInt(denomDecimalsFactor)).Int(nil)
-	return feeUSDCDecimals, nil
+	feeUSDCDecimals := new(big.Float).Mul(feeUSDC, new(big.Float).SetInt(denomDecimalsFactor))
+	// Apply the fixed fee multiplier.
+	feeUSDCDecimalsScaled, _ := new(big.Float).Mul(feeUSDCDecimals, new(big.Float).SetFloat64(f.config.GetFixedFeeMultiplier())).Int(nil)
+	return feeUSDCDecimalsScaled, nil
 }
 
 // getGasPrice returns the gas price for a given chainID in native units.

services/rfq/relayer/pricer/fee_pricer_test.go

@@ -139,3 +139,67 @@ func (s *PricerSuite) TestGetGasPrice() {
 		return expectedGasPrice.String() == gasPrice.String()
 	})
 }
+
+func (s *PricerSuite) TestGetTotalFeeWithMultiplier() {
+	// Override the fixed fee multiplier to greater than 1.
+	s.config.FeePricer.FixedFeeMultiplier = 2
+
+	// Build a new FeePricer with a mocked client for fetching gas price.
+	clientFetcher := new(fetcherMocks.ClientFetcher)
+	clientOrigin := new(clientMocks.EVM)
+	clientDestination := new(clientMocks.EVM)
+	headerOrigin := &types.Header{BaseFee: big.NewInt(100_000_000_000)}      // 100 gwei
+	headerDestination := &types.Header{BaseFee: big.NewInt(500_000_000_000)} // 500 gwei
+	clientOrigin.On(testsuite.GetFunctionName(clientOrigin.HeaderByNumber), mock.Anything, mock.Anything).Once().Return(headerOrigin, nil)
+	clientDestination.On(testsuite.GetFunctionName(clientDestination.HeaderByNumber), mock.Anything, mock.Anything).Once().Return(headerDestination, nil)
+	clientFetcher.On(testsuite.GetFunctionName(clientFetcher.GetClient), mock.Anything, big.NewInt(int64(s.origin))).Once().Return(clientOrigin, nil)
+	clientFetcher.On(testsuite.GetFunctionName(clientFetcher.GetClient), mock.Anything, big.NewInt(int64(s.destination))).Once().Return(clientDestination, nil)
+	feePricer := pricer.NewFeePricer(s.config, clientFetcher)
+	go func() { feePricer.Start(s.GetTestContext()) }()
+
+	// Calculate the total fee.
+	fee, err := feePricer.GetTotalFee(s.GetTestContext(), s.origin, s.destination, "USDC")
+	s.NoError(err)
+
+	// The expected fee should be the sum of the Origin and Destination fees, i.e. 200_500_000.
+	expectedFee := big.NewInt(200_500_000) // 200.50 usd
+	s.Equal(expectedFee, fee)
+
+	// Override the fixed fee multiplier to less than 1; should default to 1.
+	s.config.FeePricer.FixedFeeMultiplier = -1
+
+	// Build a new FeePricer with a mocked client for fetching gas price.
+	clientOrigin.On(testsuite.GetFunctionName(clientOrigin.HeaderByNumber), mock.Anything, mock.Anything).Once().Return(headerOrigin, nil)
+	clientDestination.On(testsuite.GetFunctionName(clientDestination.HeaderByNumber), mock.Anything, mock.Anything).Once().Return(headerDestination, nil)
+	clientFetcher.On(testsuite.GetFunctionName(clientFetcher.GetClient), mock.Anything, big.NewInt(int64(s.origin))).Once().Return(clientOrigin, nil)
+	clientFetcher.On(testsuite.GetFunctionName(clientFetcher.GetClient), mock.Anything, big.NewInt(int64(s.destination))).Once().Return(clientDestination, nil)
+	feePricer = pricer.NewFeePricer(s.config, clientFetcher)
+	go func() { feePricer.Start(s.GetTestContext()) }()
+
+	// Calculate the total fee.
+	fee, err = feePricer.GetTotalFee(s.GetTestContext(), s.origin, s.destination, "USDC")
+	s.NoError(err)
+
+	// The expected fee should be the sum of the Origin and Destination fees, i.e. 100_250_000.
+	expectedFee = big.NewInt(100_250_000) // 100.25 usd
+	s.Equal(expectedFee, fee)
+
+	// Reset the fixed fee multiplier to zero; should default to 1
+	s.config.FeePricer.FixedFeeMultiplier = 0
+
+	// Build a new FeePricer with a mocked client for fetching gas price.
+	clientOrigin.On(testsuite.GetFunctionName(clientOrigin.HeaderByNumber), mock.Anything, mock.Anything).Once().Return(headerOrigin, nil)
+	clientDestination.On(testsuite.GetFunctionName(clientDestination.HeaderByNumber), mock.Anything, mock.Anything).Once().Return(headerDestination, nil)
+	clientFetcher.On(testsuite.GetFunctionName(clientFetcher.GetClient), mock.Anything, big.NewInt(int64(s.origin))).Once().Return(clientOrigin, nil)
+	clientFetcher.On(testsuite.GetFunctionName(clientFetcher.GetClient), mock.Anything, big.NewInt(int64(s.destination))).Once().Return(clientDestination, nil)
+	feePricer = pricer.NewFeePricer(s.config, clientFetcher)
+	go func() { feePricer.Start(s.GetTestContext()) }()
+
+	// Calculate the total fee.
+	fee, err = feePricer.GetTotalFee(s.GetTestContext(), s.origin, s.destination, "USDC")
+	s.NoError(err)
+
+	// The expected fee should be the sum of the Origin and Destination fees, i.e. 100_250_000.
+	expectedFee = big.NewInt(100_250_000) // 100.25 usd
+	s.Equal(expectedFee, fee)
+}

services/rfq/relayer/relconfig/config.go

@@ -71,6 +71,8 @@ type FeePricerConfig struct {
 	OriginGasEstimate int `yaml:"origin_gas_estimate"`
 	// DestinationGasEstimate is the gas required to execute relay transaction on destination chain.
 	DestinationGasEstimate int `yaml:"destination_gas_estimate"`
+	// FixedFeeMultiplier is the multiplier for the fixed fee.
+	FixedFeeMultiplier float64 `yaml:"fixed_fee_multiplier"`
 	// GasPriceCacheTTLSeconds is the TTL for the gas price cache.
 	GasPriceCacheTTLSeconds int `yaml:"gas_price_cache_ttl"`
 	// TokenPriceCacheTTLSeconds is the TTL for the token price cache.
@@ -193,4 +195,14 @@ func (c Config) GetTokenName(chain uint32, addr string) (string, error) {
 	return "", fmt.Errorf("no tokenName found for chain %d and address %s", chain, addr)
 }
 
+const defaultFixedFeeMultiplier = 1
+
+// GetFixedFeeMultiplier returns the fixed fee multiplier.
+func (c Config) GetFixedFeeMultiplier() float64 {
+	if c.FeePricer.FixedFeeMultiplier <= 0 {
+		return defaultFixedFeeMultiplier
+	}
+	return c.FeePricer.FixedFeeMultiplier
+}
+
 var _ IConfig = &Config{}