core/state: access trie through Database interface, track errors (#14589)

With this commit, core/state's access to the underlying key/value database is
mediated through an interface. Database errors are tracked in StateDB and
returned by CommitTo or the new Error method.

Motivation for this change: We can remove the light client's duplicated copy of
core/state. The light client now supports node iteration, so tracing and storage
enumeration can work with the light client (not implemented in this commit).

2 files changed, 16 insertions, 30 deletions

diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index da5dc5d58..c22c56dfb 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -447,8 +447,8 @@ func (s *PublicBlockChainAPI) GetBalance(ctx context.Context, address common.Add
 	if state == nil || err != nil {
 		return nil, err
 	}
-
-	return state.GetBalance(ctx, address)
+	b := state.GetBalance(address)
+	return b, state.Error()
 }
 
 // GetBlockByNumber returns the requested block. When blockNr is -1 the chain head is returned. When fullTx is true all
@@ -529,31 +529,25 @@ func (s *PublicBlockChainAPI) GetUncleCountByBlockHash(ctx context.Context, bloc
 }
 
 // GetCode returns the code stored at the given address in the state for the given block number.
-func (s *PublicBlockChainAPI) GetCode(ctx context.Context, address common.Address, blockNr rpc.BlockNumber) (string, error) {
+func (s *PublicBlockChainAPI) GetCode(ctx context.Context, address common.Address, blockNr rpc.BlockNumber) (hexutil.Bytes, error) {
 	state, _, err := s.b.StateAndHeaderByNumber(ctx, blockNr)
 	if state == nil || err != nil {
-		return "", err
-	}
-	res, err := state.GetCode(ctx, address)
-	if len(res) == 0 || err != nil { // backwards compatibility
-		return "0x", err
+		return nil, err
 	}
-	return common.ToHex(res), nil
+	code := state.GetCode(address)
+	return code, state.Error()
 }
 
 // GetStorageAt returns the storage from the state at the given address, key and
 // block number. The rpc.LatestBlockNumber and rpc.PendingBlockNumber meta block
 // numbers are also allowed.
-func (s *PublicBlockChainAPI) GetStorageAt(ctx context.Context, address common.Address, key string, blockNr rpc.BlockNumber) (string, error) {
+func (s *PublicBlockChainAPI) GetStorageAt(ctx context.Context, address common.Address, key string, blockNr rpc.BlockNumber) (hexutil.Bytes, error) {
 	state, _, err := s.b.StateAndHeaderByNumber(ctx, blockNr)
 	if state == nil || err != nil {
-		return "0x", err
-	}
-	res, err := state.GetState(ctx, address, common.HexToHash(key))
-	if err != nil {
-		return "0x", err
+		return nil, err
 	}
-	return res.Hex(), nil
+	res := state.GetState(address, common.HexToHash(key))
+	return res[:], state.Error()
 }
 
 // callmsg is the message type used for call transitions.
@@ -978,11 +972,8 @@ func (s *PublicTransactionPoolAPI) GetTransactionCount(ctx context.Context, addr
 	if state == nil || err != nil {
 		return nil, err
 	}
-	nonce, err := state.GetNonce(ctx, address)
-	if err != nil {
-		return nil, err
-	}
-	return (*hexutil.Uint64)(&nonce), nil
+	nonce := state.GetNonce(address)
+	return (*hexutil.Uint64)(&nonce), state.Error()
 }
 
 // getTransactionBlockData fetches the meta data for the given transaction from the chain database. This is useful to
diff --git a/internal/ethapi/backend.go b/internal/ethapi/backend.go
index 68b5069d0..d122b7915 100644
--- a/internal/ethapi/backend.go
+++ b/internal/ethapi/backend.go
@@ -24,6 +24,7 @@ import (
 	"github.com/ethereum/go-ethereum/accounts"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/eth/downloader"
@@ -47,11 +48,12 @@ type Backend interface {
 	SetHead(number uint64)
 	HeaderByNumber(ctx context.Context, blockNr rpc.BlockNumber) (*types.Header, error)
 	BlockByNumber(ctx context.Context, blockNr rpc.BlockNumber) (*types.Block, error)
-	StateAndHeaderByNumber(ctx context.Context, blockNr rpc.BlockNumber) (State, *types.Header, error)
+	StateAndHeaderByNumber(ctx context.Context, blockNr rpc.BlockNumber) (*state.StateDB, *types.Header, error)
 	GetBlock(ctx context.Context, blockHash common.Hash) (*types.Block, error)
 	GetReceipts(ctx context.Context, blockHash common.Hash) (types.Receipts, error)
 	GetTd(blockHash common.Hash) *big.Int
-	GetEVM(ctx context.Context, msg core.Message, state State, header *types.Header, vmCfg vm.Config) (*vm.EVM, func() error, error)
+	GetEVM(ctx context.Context, msg core.Message, state *state.StateDB, header *types.Header, vmCfg vm.Config) (*vm.EVM, func() error, error)
+
 	// TxPool API
 	SendTx(ctx context.Context, signedTx *types.Transaction) error
 	RemoveTx(txHash common.Hash)
@@ -65,13 +67,6 @@ type Backend interface {
 	CurrentBlock() *types.Block
 }
 
-type State interface {
-	GetBalance(ctx context.Context, addr common.Address) (*big.Int, error)
-	GetCode(ctx context.Context, addr common.Address) ([]byte, error)
-	GetState(ctx context.Context, a common.Address, b common.Hash) (common.Hash, error)
-	GetNonce(ctx context.Context, addr common.Address) (uint64, error)
-}
-
 func GetAPIs(apiBackend Backend) []rpc.API {
 	nonceLock := new(AddrLocker)
 	return []rpc.API{