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).

1 files changed, 13 insertions, 19 deletions

diff --git a/light/txpool.go b/light/txpool.go
index 7276874b8..0430b280f 100644
--- a/light/txpool.go
+++ b/light/txpool.go
@@ -24,6 +24,7 @@ import (
 
 	"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/ethdb"
 	"github.com/ethereum/go-ethereum/event"
@@ -100,17 +101,18 @@ func NewTxPool(config *params.ChainConfig, eventMux *event.TypeMux, chain *Light
 }
 
 // currentState returns the light state of the current head header
-func (pool *TxPool) currentState() *LightState {
-	return NewLightState(StateTrieID(pool.chain.CurrentHeader()), pool.odr)
+func (pool *TxPool) currentState(ctx context.Context) *state.StateDB {
+	return NewState(ctx, pool.chain.CurrentHeader(), pool.odr)
 }
 
 // GetNonce returns the "pending" nonce of a given address. It always queries
 // the nonce belonging to the latest header too in order to detect if another
 // client using the same key sent a transaction.
 func (pool *TxPool) GetNonce(ctx context.Context, addr common.Address) (uint64, error) {
-	nonce, err := pool.currentState().GetNonce(ctx, addr)
-	if err != nil {
-		return 0, err
+	state := pool.currentState(ctx)
+	nonce := state.GetNonce(addr)
+	if state.Error() != nil {
+		return 0, state.Error()
 	}
 	sn, ok := pool.nonce[addr]
 	if ok && sn > nonce {
@@ -357,13 +359,9 @@ func (pool *TxPool) validateTx(ctx context.Context, tx *types.Transaction) error
 		return core.ErrInvalidSender
 	}
 	// Last but not least check for nonce errors
-	currentState := pool.currentState()
-	if n, err := currentState.GetNonce(ctx, from); err == nil {
-		if n > tx.Nonce() {
-			return core.ErrNonceTooLow
-		}
-	} else {
-		return err
+	currentState := pool.currentState(ctx)
+	if n := currentState.GetNonce(from); n > tx.Nonce() {
+		return core.ErrNonceTooLow
 	}
 
 	// Check the transaction doesn't exceed the current
@@ -382,12 +380,8 @@ func (pool *TxPool) validateTx(ctx context.Context, tx *types.Transaction) error
 
 	// Transactor should have enough funds to cover the costs
 	// cost == V + GP * GL
-	if b, err := currentState.GetBalance(ctx, from); err == nil {
-		if b.Cmp(tx.Cost()) < 0 {
-			return core.ErrInsufficientFunds
-		}
-	} else {
-		return err
+	if b := currentState.GetBalance(from); b.Cmp(tx.Cost()) < 0 {
+		return core.ErrInsufficientFunds
 	}
 
 	// Should supply enough intrinsic gas
@@ -395,7 +389,7 @@ func (pool *TxPool) validateTx(ctx context.Context, tx *types.Transaction) error
 		return core.ErrIntrinsicGas
 	}
 
-	return nil
+	return currentState.Error()
 }
 
 // add validates a new transaction and sets its state pending if processable.