rpc, feemarket: store base fee in event (#673)

* store base fee in event

* update changelog

rpc/ethereum/backend/backend.go

@@ -826,22 +826,24 @@ func (e *EVMBackend) BaseFee(height int64) (*big.Int, error) {
 		return nil, nil
 	}
 
-	res, err := e.queryClient.FeeMarket.BaseFee(types.ContextWithHeight(height), &feemarkettypes.QueryBaseFeeRequest{})
+	blockRes, err := e.clientCtx.Client.BlockResults(e.ctx, &height)
 	if err != nil {
 		return nil, err
 	}
 
-	if res.BaseFee != nil {
+	baseFee := types.BaseFeeFromEvents(blockRes.EndBlockEvents)
+	if baseFee != nil {
+		return baseFee, nil
+	}
+
+	// If we cannot find in events, we tried to get it from the state.
+	// It will return feemarket.baseFee if london is activated but feemarket is not enable
+	res, err := e.queryClient.FeeMarket.BaseFee(types.ContextWithHeight(height), &feemarkettypes.QueryBaseFeeRequest{})
+	if err == nil && res.BaseFee != nil {
 		return res.BaseFee.BigInt(), nil
 	}
 
-	resParams, err := e.queryClient.FeeMarket.Params(types.ContextWithHeight(height), &feemarkettypes.QueryParamsRequest{})
-	if err != nil {
-		return nil, err
-	}
-
-	baseFee := big.NewInt(resParams.Params.InitialBaseFee)
-	return baseFee, nil
+	return nil, nil
 }
 
 // GetFilteredBlocks returns the block height list match the given bloom filters.

rpc/ethereum/namespaces/eth/filters/api.go

@@ -3,7 +3,6 @@ package filters
 import (
 	"context"
 	"fmt"
-	"math/big"
 	"sync"
 	"time"
 
@@ -18,7 +17,6 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	ethtypes "github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/eth/filters"
-	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rpc"
 
 	evmtypes "github.com/tharsis/ethermint/x/evm/types"
@@ -239,9 +237,6 @@ func (api *PublicFilterAPI) NewBlockFilter() rpc.ID {
 		return rpc.ID(fmt.Sprintf("error creating block filter: %s", err.Error()))
 	}
 
-	// TODO: use events to get the base fee amount
-	baseFee := big.NewInt(params.InitialBaseFee)
-
 	api.filters[headerSub.ID()] = &filter{typ: filters.BlocksSubscription, deadline: time.NewTimer(deadline), hashes: []common.Hash{}, s: headerSub}
 
 	go func(headersCh <-chan coretypes.ResultEvent, errCh <-chan error) {
@@ -263,6 +258,8 @@ func (api *PublicFilterAPI) NewBlockFilter() rpc.ID {
 					continue
 				}
 
+				baseFee := types.BaseFeeFromEvents(data.ResultEndBlock.Events)
+
 				header := types.EthHeaderFromTendermint(data.Header, baseFee)
 				api.filtersMu.Lock()
 				if f, found := api.filters[headerSub.ID()]; found {
@@ -296,9 +293,6 @@ func (api *PublicFilterAPI) NewHeads(ctx context.Context) (*rpc.Subscription, er
 		return &rpc.Subscription{}, err
 	}
 
-	// TODO: use events to get the base fee amount
-	baseFee := big.NewInt(params.InitialBaseFee)
-
 	go func(headersCh <-chan coretypes.ResultEvent) {
 		defer cancelSubs()
 
@@ -316,6 +310,8 @@ func (api *PublicFilterAPI) NewHeads(ctx context.Context) (*rpc.Subscription, er
 					continue
 				}
 
+				baseFee := types.BaseFeeFromEvents(data.ResultEndBlock.Events)
+
 				header := types.EthHeaderFromTendermint(data.Header, baseFee)
 				err = notifier.Notify(rpcSub.ID, header)
 				if err != nil {

rpc/ethereum/types/utils.go

@@ -1,11 +1,15 @@
 package types
 
 import (
+	"bytes"
 	"context"
 	"encoding/hex"
 	"fmt"
 	"math/big"
 
+	abci "github.com/tendermint/tendermint/abci/types"
+	feemarkettypes "github.com/tharsis/ethermint/x/feemarket/types"
+
 	tmbytes "github.com/tendermint/tendermint/libs/bytes"
 	tmtypes "github.com/tendermint/tendermint/types"
 
@@ -244,3 +248,24 @@ func NewRPCTransaction(
 	}
 	return result, nil
 }
+
+// BaseFeeFromEvents parses the feemarket basefee from cosmos events
+func BaseFeeFromEvents(events []abci.Event) *big.Int {
+	for _, event := range events {
+		if event.Type != feemarkettypes.EventTypeFeeMarket {
+			continue
+		}
+
+		for _, attr := range event.Attributes {
+			if bytes.Equal(attr.Key, []byte(feemarkettypes.AttributeKeyBaseFee)) {
+				result, success := new(big.Int).SetString(string(attr.Value), 10)
+				if success {
+					return result
+				}
+
+				return nil
+			}
+		}
+	}
+	return nil
+}