Add erigon_getBalanceChangesInBlock RPC endpoint (#4609)

* Add eth_getBalanceChangesInBlock RPC endpoint

* Fix lints

* added assertion for one test

* moved balance change api from eth to erigon

Co-authored-by: fatemebagherii <fa.bagheri.a@gmail.com>

cmd/rpcdaemon/commands/erigon_api.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/ledgerwatch/erigon-lib/kv"
 	"github.com/ledgerwatch/erigon/common"
+	"github.com/ledgerwatch/erigon/common/hexutil"
 	"github.com/ledgerwatch/erigon/core/types"
 	"github.com/ledgerwatch/erigon/p2p"
 	"github.com/ledgerwatch/erigon/rpc"
@@ -20,6 +21,7 @@ type ErigonAPI interface {
 	GetHeaderByNumber(ctx context.Context, number rpc.BlockNumber) (*types.Header, error)
 	GetHeaderByHash(_ context.Context, hash common.Hash) (*types.Header, error)
 	GetBlockByTimestamp(ctx context.Context, timeStamp rpc.Timestamp, fullTx bool) (map[string]interface{}, error)
+	GetBalanceChangesInBlock(ctx context.Context, blockNrOrHash rpc.BlockNumberOrHash) (map[common.Address]*hexutil.Big, error)
 
 	// Receipt related (see ./erigon_receipts.go)
 	GetLogsByHash(ctx context.Context, hash common.Hash) ([][]*types.Log, error)

cmd/rpcdaemon/commands/erigon_block.go

@@ -1,15 +1,21 @@
 package commands
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
 	"sort"
 
+	"github.com/holiman/uint256"
 	"github.com/ledgerwatch/erigon-lib/kv"
 	"github.com/ledgerwatch/erigon/common"
+	"github.com/ledgerwatch/erigon/common/changeset"
+	"github.com/ledgerwatch/erigon/common/dbutils"
+	"github.com/ledgerwatch/erigon/common/hexutil"
 	"github.com/ledgerwatch/erigon/core/rawdb"
 	"github.com/ledgerwatch/erigon/core/types"
+	"github.com/ledgerwatch/erigon/core/types/accounts"
 	"github.com/ledgerwatch/erigon/internal/ethapi"
 	"github.com/ledgerwatch/erigon/rpc"
 	"github.com/ledgerwatch/erigon/turbo/rpchelper"
@@ -168,3 +174,65 @@ func buildBlockResponse(db kv.Tx, blockNum uint64, fullTx bool) (map[string]inte
 	}
 	return response, err
 }
+
+func (api *ErigonImpl) GetBalanceChangesInBlock(ctx context.Context, blockNrOrHash rpc.BlockNumberOrHash) (map[common.Address]*hexutil.Big, error) {
+	tx, err := api.db.BeginRo(ctx)
+	if err != nil {
+		return nil, err
+	}
+	defer tx.Rollback()
+
+	blockNumber, _, _, err := rpchelper.GetBlockNumber(blockNrOrHash, tx, api.filters)
+	if err != nil {
+		return nil, err
+	}
+
+	c, err := tx.Cursor(kv.AccountChangeSet)
+	if err != nil {
+		return nil, err
+	}
+	defer c.Close()
+
+	startkey := dbutils.EncodeBlockNumber(blockNumber)
+
+	decodeFn := changeset.Mapper[kv.AccountChangeSet].Decode
+
+	balancesMapping := make(map[common.Address]*hexutil.Big)
+
+	newReader, err := rpchelper.CreateStateReader(ctx, tx, blockNrOrHash, api.filters, api.stateCache)
+	if err != nil {
+		return nil, err
+	}
+
+	for dbKey, dbValue, _ := c.Seek(startkey); bytes.Equal(dbKey, startkey) && dbKey != nil; dbKey, dbValue, _ = c.Next() {
+		_, addressBytes, v, err := decodeFn(dbKey, dbValue)
+		if err != nil {
+			return nil, err
+		}
+
+		var oldAcc accounts.Account
+		if err = oldAcc.DecodeForStorage(v); err != nil {
+			return nil, err
+		}
+		oldBalance := oldAcc.Balance
+
+		address := common.BytesToAddress(addressBytes)
+
+		newAcc, err := newReader.ReadAccountData(address)
+		if err != nil {
+			return nil, err
+		}
+
+		newBalance := uint256.NewInt(0)
+		if newAcc != nil {
+			newBalance = &newAcc.Balance
+		}
+
+		if !oldBalance.Eq(newBalance) {
+			newBalanceDesc := (*hexutil.Big)(newBalance.ToBig())
+			balancesMapping[address] = newBalanceDesc
+		}
+	}
+
+	return balancesMapping, nil
+}

cmd/rpcdaemon/commands/eth_api_test.go

@@ -5,6 +5,8 @@ import (
 	"fmt"
 	"testing"
 
+	"github.com/holiman/uint256"
+	"github.com/ledgerwatch/erigon/common/hexutil"
 	"github.com/ledgerwatch/erigon/core"
 	"github.com/ledgerwatch/erigon/internal/ethapi"
 	"github.com/ledgerwatch/erigon/rpc"
@@ -16,6 +18,29 @@ import (
 	"github.com/ledgerwatch/erigon/common"
 )
 
+func TestGetBalanceChangesInBlock(t *testing.T) {
+	assert := assert.New(t)
+	myBlockNum := rpc.BlockNumberOrHashWithNumber(0)
+
+	db := rpcdaemontest.CreateTestKV(t)
+	stateCache := kvcache.New(kvcache.DefaultCoherentConfig)
+	api := NewErigonAPI(NewBaseApi(nil, stateCache, snapshotsync.NewBlockReader(), false), db, nil)
+	balances, err := api.GetBalanceChangesInBlock(context.Background(), myBlockNum)
+	if err != nil {
+		t.Errorf("calling GetBalanceChangesInBlock resulted in an error: %v", err)
+	}
+	expected := map[common.Address]*hexutil.Big{
+		common.HexToAddress("0x0D3ab14BBaD3D99F4203bd7a11aCB94882050E7e"): (*hexutil.Big)(uint256.NewInt(200000000000000000).ToBig()),
+		common.HexToAddress("0x703c4b2bD70c169f5717101CaeE543299Fc946C7"): (*hexutil.Big)(uint256.NewInt(300000000000000000).ToBig()),
+		common.HexToAddress("0x71562b71999873DB5b286dF957af199Ec94617F7"): (*hexutil.Big)(uint256.NewInt(9000000000000000000).ToBig()),
+	}
+	assert.Equal(len(expected), len(balances))
+	for i := range balances {
+		assert.Contains(expected, i, "%s is not expected to be present in the output.", i)
+		assert.Equal(balances[i], expected[i], "the value for %s is expected to be %v, but got %v.", i, expected[i], balances[i])
+	}
+}
+
 func TestGetTransactionReceipt(t *testing.T) {
 	db := rpcdaemontest.CreateTestKV(t)
 	stateCache := kvcache.New(kvcache.DefaultCoherentConfig)