Pass static value into CalcPreVerificationGasFunc (#158)

Author: hazim-j

pkg/gas/overhead.go

@@ -48,6 +48,8 @@ func NewDefaultOverhead() *Overhead {
 	}
 }
 
+// SetCalcPreVerificationGasFunc allows a custom function to be defined that can control how it calculates
+// PVG. This is useful for networks that have different models for gas.
 func (ov *Overhead) SetCalcPreVerificationGasFunc(fn CalcPreVerificationGasFunc) {
 	ov.calcPVGFunc = fn
 }
@@ -68,29 +70,29 @@ func (ov *Overhead) CalcPreVerificationGas(op *userop.UserOperation) (*big.Int,
 		return nil, err
 	}
 
-	// Use value from CalcPreVerificationGasFunc if set
-	g, err := ov.calcPVGFunc(tmp)
-	if err != nil {
-		return nil, err
-	}
-	if g != nil {
-		return g, nil
-	}
-
+	// Calculate static value from pre-defined parameters
 	packed := tmp.Pack()
 	lengthInWord := float64(len(packed)+31) / 32
 	callDataCost := float64(0)
-
 	for _, b := range packed {
 		if b == byte(0) {
 			callDataCost += ov.zeroByte
 		} else {
 			callDataCost += ov.nonZeroByte
 		}
 	}
-
 	pvg := callDataCost + (ov.fixed / ov.minBundleSize) + ov.perUserOp + (ov.perUserOpWord * lengthInWord)
-	return big.NewInt(int64(math.Round(pvg))), nil
+	static := big.NewInt(int64(math.Round(pvg)))
+
+	// Use value from CalcPreVerificationGasFunc if set, otherwise return the static value.
+	g, err := ov.calcPVGFunc(tmp, static)
+	if err != nil {
+		return nil, err
+	}
+	if g != nil {
+		return g, nil
+	}
+	return static, nil
 }
 
 // NonZeroValueCall returns an expected gas cost of using the CALL opcode in the context of EIP-4337.

pkg/gas/pvg.go

@@ -14,10 +14,12 @@ import (
 	"github.com/stackup-wallet/stackup-bundler/pkg/userop"
 )
 
-type CalcPreVerificationGasFunc = func(op *userop.UserOperation) (*big.Int, error)
+// CalcPreVerificationGasFunc defines an interface for a function to calculate PVG given a userOp and a static
+// value. The static input is the value derived from the default overheads.
+type CalcPreVerificationGasFunc = func(op *userop.UserOperation, static *big.Int) (*big.Int, error)
 
 func calcPVGFuncNoop() CalcPreVerificationGasFunc {
-	return func(op *userop.UserOperation) (*big.Int, error) {
+	return func(op *userop.UserOperation, static *big.Int) (*big.Int, error) {
 		return nil, nil
 	}
 }
@@ -30,7 +32,7 @@ func CalcArbitrumPVGWithEthClient(
 ) CalcPreVerificationGasFunc {
 	pk, _ := crypto.GenerateKey()
 	dummy, _ := signer.New(hexutil.Encode(crypto.FromECDSA(pk))[2:])
-	return func(op *userop.UserOperation) (*big.Int, error) {
+	return func(op *userop.UserOperation, static *big.Int) (*big.Int, error) {
 		// Pack handleOps method inputs
 		ho, err := methods.HandleOpsMethod.Inputs.Pack(
 			[]entrypoint.UserOperation{entrypoint.UserOperation(*op)},
@@ -65,11 +67,11 @@ func CalcArbitrumPVGWithEthClient(
 			return nil, err
 		}
 
-		// Return GasEstimateForL1 as PVG
+		// Return static + GasEstimateForL1 as PVG
 		gas, err := nodeinterface.DecodeGasEstimateL1ComponentOutput(out)
 		if err != nil {
 			return nil, err
 		}
-		return big.NewInt(int64(gas.GasEstimateForL1)), nil
+		return big.NewInt(0).Add(static, big.NewInt(int64(gas.GasEstimateForL1))), nil
 	}
 }