Merge pull request #142 from renproject/feat/cosmos-estimate-gas

Fix the gas price for cosmos compat chains

chain/cosmos/tx.go

@@ -30,17 +30,27 @@ const (
 	DefaultChainID = pack.String("testnet")
 	// DefaultSignMode used in signing the tx
 	DefaultSignMode = 1
+	// DefaultDecimalsDivisor is used when estimating gas prices for some Cosmos
+	// chains, so that the result is an integer.
+	// For example, the recommended Terra gas price is currently 0.01133 uluna.
+	// To ensure we're only dealing with integers, the value can be represented
+	// as 1133. When the transaction builder is calculating fees, it will divide
+	// the total by the divisor (in this case 1e5), to calculate the actual
+	// value.
+	DefaultDecimalsDivisor = 1
 )
 
 // TxBuilderOptions only contains necessary options to build tx from tx builder
 type TxBuilderOptions struct {
-	ChainID pack.String
+	ChainID         pack.String
+	DecimalsDivisor pack.U256
 }
 
 // DefaultTxBuilderOptions returns TxBuilderOptions with the default settings.
 func DefaultTxBuilderOptions() TxBuilderOptions {
 	return TxBuilderOptions{
-		ChainID: DefaultChainID,
+		ChainID:         DefaultChainID,
+		DecimalsDivisor: pack.NewU256FromU64(DefaultDecimalsDivisor),
 	}
 }
 
@@ -50,20 +60,27 @@ func (opts TxBuilderOptions) WithChainID(chainID pack.String) TxBuilderOptions {
 	return opts
 }
 
+func (opts TxBuilderOptions) WithDecimalsDivisor(decimalDivisor pack.U256) TxBuilderOptions {
+	opts.DecimalsDivisor = decimalDivisor
+	return opts
+}
+
 type txBuilder struct {
-	client   *Client
-	chainID  pack.String
-	signMode int32
+	client          *Client
+	chainID         pack.String
+	signMode        int32
+	decimalsDivisor pack.U256
 }
 
 // NewTxBuilder returns an implementation of the transaction builder interface
 // from the Cosmos Compat API, and exposes the functionality to build simple
 // Cosmos based transactions.
 func NewTxBuilder(options TxBuilderOptions, client *Client) account.TxBuilder {
 	return txBuilder{
-		signMode: DefaultSignMode,
-		client:   client,
-		chainID:  options.ChainID,
+		signMode:        DefaultSignMode,
+		client:          client,
+		chainID:         options.ChainID,
+		decimalsDivisor: options.DecimalsDivisor,
 	}
 }
 
@@ -107,7 +124,7 @@ func (builder txBuilder) BuildTx(ctx context.Context, fromPubKey *id.PubKey, to
 
 	fees := Coins{Coin{
 		Denom:  builder.client.opts.CoinDenom,
-		Amount: pack.NewU64(gasPrice.Mul(gasLimit).Int().Uint64()),
+		Amount: pack.NewU64(gasPrice.Mul(gasLimit).Div(builder.decimalsDivisor).Int().Uint64()),
 	}}
 
 	accountNumber, err := builder.client.AccountNumber(ctx, from)

chain/ethereum/gas.go

@@ -29,7 +29,7 @@ var (
 )
 
 type feeHistoryResult struct {
-	Reward      [][]string `json:"reward"`
+	Reward [][]string `json:"reward"`
 }
 
 // GasOptions allow a user to configure the parameters used while heuristically recommending

chain/terra/terra.go

@@ -1,12 +1,21 @@
 package terra
 
 import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strconv"
+
 	"github.com/cosmos/cosmos-sdk/types"
 	"github.com/renproject/multichain/api/account"
 	"github.com/renproject/multichain/chain/cosmos"
+	"github.com/renproject/pack"
 	"github.com/terra-money/core/app"
 )
 
+const DefaultTerraDecimalsDivisor = 1e5
+
 type (
 	// Client re-exports cosmos.Client
 	Client = cosmos.Client
@@ -54,3 +63,40 @@ func NewClient(opts ClientOptions) *Client {
 func NewTxBuilder(opts TxBuilderOptions, client *Client) account.TxBuilder {
 	return cosmos.NewTxBuilder(opts, client)
 }
+
+type GasEstimator struct {
+	url         string
+	decimals    int
+	fallbackGas pack.U256
+}
+
+func NewHttpGasEstimator(url string, decimals int, fallbackGas pack.U256) GasEstimator {
+	return GasEstimator{
+		url:         url,
+		decimals:    decimals,
+		fallbackGas: fallbackGas,
+	}
+}
+
+func (gasEstimator GasEstimator) EstimateGas(ctx context.Context) (pack.U256, pack.U256, error) {
+	response, err := http.Get(gasEstimator.url)
+	if err != nil {
+		return gasEstimator.fallbackGas, gasEstimator.fallbackGas, err
+	}
+	defer response.Body.Close()
+
+	var results map[string]string
+	if err := json.NewDecoder(response.Body).Decode(&results); err != nil {
+		return gasEstimator.fallbackGas, gasEstimator.fallbackGas, err
+	}
+	gasPriceStr, ok := results["uluna"]
+	if !ok {
+		return gasEstimator.fallbackGas, gasEstimator.fallbackGas, fmt.Errorf("no uluna in response")
+	}
+	gasPriceFloat, err := strconv.ParseFloat(gasPriceStr, 64)
+	if err != nil {
+		return gasEstimator.fallbackGas, gasEstimator.fallbackGas, fmt.Errorf("invalid gas price, %v", err)
+	}
+	gasPrice := uint64(gasPriceFloat * float64(gasEstimator.decimals))
+	return pack.NewU256FromUint64(gasPrice), pack.NewU256FromUint64(gasPrice), nil
+}