EvmFeeEstimator return Optimistic Rollup's L1BaseFee

core/chains/evm/gas/chainoracles/l1_gas_price_oracle.go

@@ -0,0 +1,168 @@
+package chainoracles
+
+import (
+	"context"
+	"fmt"
+	"math/big"
+	"sync"
+	"time"
+
+	"github.com/ethereum/go-ethereum"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/pkg/errors"
+
+	"github.com/smartcontractkit/chainlink/v2/core/assets"
+	evmclient "github.com/smartcontractkit/chainlink/v2/core/chains/evm/client"
+	"github.com/smartcontractkit/chainlink/v2/core/config"
+	"github.com/smartcontractkit/chainlink/v2/core/logger"
+	"github.com/smartcontractkit/chainlink/v2/core/utils"
+)
+
+//go:generate mockery --quiet --name ethClient --output ./mocks/ --case=underscore --structname ETHClient
+type ethClient interface {
+	CallContract(ctx context.Context, msg ethereum.CallMsg, blockNumber *big.Int) ([]byte, error)
+}
+
+// Reads L2-specific precompiles and caches the l1GasPrice set by the L2.
+type l1GasPriceOracle struct {
+	client     ethClient
+	pollPeriod time.Duration
+	logger     logger.Logger
+	address    string
+	selector   string
+
+	l1GasPriceMu sync.RWMutex
+	l1GasPrice   *assets.Wei
+
+	chInitialised chan struct{}
+	chStop        utils.StopChan
+	chDone        chan struct{}
+	utils.StartStopOnce
+}
+
+const (
+	// ArbGasInfoAddress is the address of the "Precompiled contract that exists in every Arbitrum chain."
+	// https://github.com/OffchainLabs/nitro/blob/f7645453cfc77bf3e3644ea1ac031eff629df325/contracts/src/precompiles/ArbGasInfo.sol
+	ArbGasInfoAddress = "0x000000000000000000000000000000000000006C"
+	// ArbGasInfo_getL1BaseFeeEstimate is the a hex encoded call to:
+	// `function getL1BaseFeeEstimate() external view returns (uint256);`
+	ArbGasInfo_getL1BaseFeeEstimate = "f5d6ded7"
+
+	// GasOracleAddress is the address of the precompiled contract that exists on OP stack chain.
+	// This is the case for Optimism and Base.
+	OPGasOracleAddress = "0x420000000000000000000000000000000000000F"
+	// GasOracle_l1BaseFee is the a hex encoded call to:
+	// `function l1BaseFee() external view returns (uint256);`
+	OPGasOracle_l1BaseFee = "519b4bd3"
+
+	// Interval at which to poll for L1BaseFee. A good starting point is the L1 block time.
+	PollPeriod = 12 * time.Second
+)
+
+func NewL1GasPriceOracle(lggr logger.Logger, ethClient ethClient, chainType config.ChainType) L1Oracle {
+	var address, selector string
+	switch chainType {
+	case config.ChainArbitrum:
+		address = ArbGasInfoAddress
+		selector = ArbGasInfo_getL1BaseFeeEstimate
+	case config.ChainOptimismBedrock:
+		address = OPGasOracleAddress
+		selector = OPGasOracle_l1BaseFee
+	default:
+		return nil
+	}
+
+	return &l1GasPriceOracle{
+		client:        ethClient,
+		pollPeriod:    PollPeriod,
+		logger:        lggr.Named(fmt.Sprintf("L1GasPriceOracle(%s)", chainType)),
+		address:       address,
+		selector:      selector,
+		chInitialised: make(chan struct{}),
+		chStop:        make(chan struct{}),
+		chDone:        make(chan struct{}),
+	}
+}
+
+func (o *l1GasPriceOracle) Name() string {
+	return o.logger.Name()
+}
+
+func (o *l1GasPriceOracle) Start(ctx context.Context) error {
+	return o.StartOnce(o.Name(), func() error {
+		go o.run()
+		<-o.chInitialised
+		return nil
+	})
+}
+func (o *l1GasPriceOracle) Close() error {
+	return o.StopOnce(o.Name(), func() error {
+		close(o.chStop)
+		<-o.chDone
+		return nil
+	})
+}
+
+func (o *l1GasPriceOracle) Ready() error { return o.StartStopOnce.Ready() }
+
+func (o *l1GasPriceOracle) HealthReport() map[string]error {
+	return map[string]error{o.Name(): o.StartStopOnce.Healthy()}
+}
+
+func (o *l1GasPriceOracle) run() {
+	defer close(o.chDone)
+
+	t := o.refresh()
+	close(o.chInitialised)
+
+	for {
+		select {
+		case <-o.chStop:
+			return
+		case <-t.C:
+			t = o.refresh()
+		}
+	}
+}
+
+func (o *l1GasPriceOracle) refresh() (t *time.Timer) {
+	t = time.NewTimer(utils.WithJitter(o.pollPeriod))
+
+	ctx, cancel := o.chStop.CtxCancel(evmclient.ContextWithDefaultTimeout())
+	defer cancel()
+
+	precompile := common.HexToAddress(o.address)
+	b, err := o.client.CallContract(ctx, ethereum.CallMsg{
+		To:   &precompile,
+		Data: common.Hex2Bytes(o.selector),
+	}, big.NewInt(-1))
+	if err != nil {
+		return
+	}
+
+	if len(b) != 32 { // returns uint256;
+		o.logger.Warnf("return data length (%d) different than expected (%d)", len(b), 32)
+		return
+	}
+	price := new(big.Int).SetBytes(b)
+
+	o.l1GasPriceMu.Lock()
+	defer o.l1GasPriceMu.Unlock()
+	o.l1GasPrice = assets.NewWei(price)
+	return
+}
+
+func (o *l1GasPriceOracle) L1GasPrice(_ context.Context) (l1GasPrice *assets.Wei, err error) {
+	ok := o.IfStarted(func() {
+		o.l1GasPriceMu.RLock()
+		l1GasPrice = o.l1GasPrice
+		o.l1GasPriceMu.RUnlock()
+	})
+	if !ok {
+		return l1GasPrice, errors.New("L1GasPriceOracle is not started; cannot estimate gas")
+	}
+	if l1GasPrice == nil {
+		return l1GasPrice, errors.New("failed to get l1 gas price; gas price not set")
+	}
+	return
+}

core/chains/evm/gas/chainoracles/l1_gas_price_oracle_test.go

@@ -0,0 +1,83 @@
+package chainoracles
+
+import (
+	"fmt"
+	"math/big"
+	"testing"
+
+	"github.com/ethereum/go-ethereum"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+
+	"github.com/smartcontractkit/chainlink/v2/core/assets"
+	"github.com/smartcontractkit/chainlink/v2/core/chains/evm/gas/chainoracles/mocks"
+	"github.com/smartcontractkit/chainlink/v2/core/config"
+	"github.com/smartcontractkit/chainlink/v2/core/internal/testutils"
+	"github.com/smartcontractkit/chainlink/v2/core/logger"
+)
+
+func TestL1GasPriceOracle(t *testing.T) {
+	t.Parallel()
+
+	t.Run("Unsupported ChainType returns nil", func(t *testing.T) {
+		ethClient := mocks.NewETHClient(t)
+
+		oracle := NewL1GasPriceOracle(logger.TestLogger(t), ethClient, config.ChainCelo)
+		assert.Nil(t, oracle)
+	})
+
+	t.Run("Calling L1GasPrice on unstarted L1Oracle returns error", func(t *testing.T) {
+		ethClient := mocks.NewETHClient(t)
+
+		oracle := NewL1GasPriceOracle(logger.TestLogger(t), ethClient, config.ChainOptimismBedrock)
+
+		_, err := oracle.L1GasPrice(testutils.Context(t))
+		assert.EqualError(t, err, "L1GasPriceOracle is not started; cannot estimate gas")
+	})
+
+	t.Run("Calling L1GasPrice on started Arbitrum L1Oracle returns Arbitrum l1GasPrice", func(t *testing.T) {
+		l1BaseFee := big.NewInt(100)
+
+		ethClient := mocks.NewETHClient(t)
+		ethClient.On("CallContract", mock.Anything, mock.IsType(ethereum.CallMsg{}), mock.IsType(&big.Int{})).Run(func(args mock.Arguments) {
+			callMsg := args.Get(1).(ethereum.CallMsg)
+			blockNumber := args.Get(2).(*big.Int)
+			assert.Equal(t, ArbGasInfoAddress, callMsg.To.String())
+			assert.Equal(t, ArbGasInfo_getL1BaseFeeEstimate, fmt.Sprintf("%x", callMsg.Data))
+			assert.Equal(t, big.NewInt(-1), blockNumber)
+		}).Return(common.BigToHash(l1BaseFee).Bytes(), nil)
+
+		oracle := NewL1GasPriceOracle(logger.TestLogger(t), ethClient, config.ChainArbitrum)
+		require.NoError(t, oracle.Start(testutils.Context(t)))
+		t.Cleanup(func() { assert.NoError(t, oracle.Close()) })
+
+		gasPrice, err := oracle.L1GasPrice(testutils.Context(t))
+		require.NoError(t, err)
+
+		assert.Equal(t, assets.NewWei(l1BaseFee), gasPrice)
+	})
+
+	t.Run("Calling L1GasPrice on started OPStack L1Oracle returns OPStack l1GasPrice", func(t *testing.T) {
+		l1BaseFee := big.NewInt(200)
+
+		ethClient := mocks.NewETHClient(t)
+		ethClient.On("CallContract", mock.Anything, mock.IsType(ethereum.CallMsg{}), mock.IsType(&big.Int{})).Run(func(args mock.Arguments) {
+			callMsg := args.Get(1).(ethereum.CallMsg)
+			blockNumber := args.Get(2).(*big.Int)
+			assert.Equal(t, OPGasOracleAddress, callMsg.To.String())
+			assert.Equal(t, OPGasOracle_l1BaseFee, fmt.Sprintf("%x", callMsg.Data))
+			assert.Equal(t, big.NewInt(-1), blockNumber)
+		}).Return(common.BigToHash(l1BaseFee).Bytes(), nil)
+
+		oracle := NewL1GasPriceOracle(logger.TestLogger(t), ethClient, config.ChainOptimismBedrock)
+		require.NoError(t, oracle.Start(testutils.Context(t)))
+		t.Cleanup(func() { assert.NoError(t, oracle.Close()) })
+
+		gasPrice, err := oracle.L1GasPrice(testutils.Context(t))
+		require.NoError(t, err)
+
+		assert.Equal(t, assets.NewWei(l1BaseFee), gasPrice)
+	})
+}