EvmFeeEstimator return Optimistic Rollup's L1BaseFee

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

@@ -0,0 +1,151 @@
+package chainoracles
+
+import (
+	"context"
+	"fmt"
+	"math/big"
+	"sync"
+	"time"
+
+	"github.com/ethereum/go-ethereum"
+	"github.com/ethereum/go-ethereum/common"
+
+	"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"
+)
+
+type OracleType string
+
+// Reads L2-specific precompiles and caches the l1GasPrice set by the L2.
+type l1GasPriceOracle struct {
+	client     evmclient.Client
+	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 in every OP stack chain."
+	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 evmclient.Client, 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("%d L1GasPriceOracle", chainType)),
+		address:    address,
+		selector:   selector,
+	}
+}
+
+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() (err error) {
+		close(o.chStop)
+		<-o.chDone
+		return
+	})
+}
+
+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) (*assets.Wei, error) {
+	o.l1GasPriceMu.RLock()
+	defer o.l1GasPriceMu.RUnlock()
+	return o.l1GasPrice, nil
+}

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

@@ -0,0 +1,18 @@
+package chainoracles
+
+import (
+	"context"
+
+	"github.com/smartcontractkit/chainlink/v2/core/assets"
+	"github.com/smartcontractkit/chainlink/v2/core/services"
+)
+
+// L1Oracle provides interface for fetching L1-specific fee components if the chain is an L2.
+// For example, on Optimistic Rollups, this oracle can return rollup-specific l1BaseFee
+//
+//go:generate mockery --quiet --name L1Oracle --output ./mocks/ --case=underscore
+type L1Oracle interface {
+	services.ServiceCtx
+
+	L1GasPrice(ctx context.Context) (*assets.Wei, error)
+}

core/chains/evm/gas/fixed_price_estimator.go

@@ -4,6 +4,7 @@ import (
 	"context"
 
 	"github.com/pkg/errors"
+
 	commonfee "github.com/smartcontractkit/chainlink/v2/common/fee"
 	feetypes "github.com/smartcontractkit/chainlink/v2/common/fee/types"
 	"github.com/smartcontractkit/chainlink/v2/core/assets"