WIP

eth/backend.go

@@ -47,9 +47,11 @@ type backend struct {
 	abiMap       map[string]*abi.ABI
 	nonceManager *NonceManager
 	signer       types.Signer
+
+	maxGasPrice *big.Int
 }
 
-func NewBackend(client *ethclient.Client, signer types.Signer) (Backend, error) {
+func NewBackend(client *ethclient.Client, signer types.Signer, maxGasPrice *big.Int) (Backend, error) {
 	abiMap, err := makeABIMap()
 	if err != nil {
 		return nil, err
@@ -60,6 +62,7 @@ func NewBackend(client *ethclient.Client, signer types.Signer) (Backend, error)
 		abiMap,
 		NewNonceManager(client),
 		signer,
+		maxGasPrice,
 	}, nil
 }
 
@@ -99,6 +102,19 @@ func (b *backend) SendTransaction(ctx context.Context, tx *types.Transaction) er
 	return nil
 }
 
+func (b *backend) SuggestGasPrice(ctx context.Context) (*big.Int, error) {
+	gp, err := b.Client.SuggestGasPrice(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	if b.maxGasPrice != nil && gp.Cmp(b.maxGasPrice) >= 0 {
+		return nil, fmt.Errorf("current gas price exceeds maximum gas price")
+	}
+
+	return gp, nil
+}
+
 type txLog struct {
 	method string
 	inputs string

eth/backend_test.go

@@ -80,7 +80,7 @@ func TestSendTransaction_SendErr_DontUpdateNonce(t *testing.T) {
 	signedTx, err := types.SignTx(tx, signer, privateKey)
 	require.Nil(t, err)
 
-	bi, err := NewBackend(client, signer)
+	bi, err := NewBackend(client, signer, nil)
 	require.Nil(t, err)
 
 	nonceLockBefore := bi.(*backend).nonceManager.getNonceLock(fromAddress)

eth/client.go

@@ -158,7 +158,7 @@ func NewClient(accountAddr ethcommon.Address, keystoreDir string, eth *ethclient
 
 	signer := types.NewEIP155Signer(chainID)
 
-	backend, err := NewBackend(eth, signer)
+	backend, err := NewBackend(eth, signer, nil)
 	if err != nil {
 		return nil, err
 	}