remove currentStateLock (#741)

Author: Darioush Jalali

core/txpool/legacypool/legacypool.go

@@ -227,9 +227,6 @@ type LegacyPool struct {
 	signer      types.Signer
 	mu          sync.RWMutex
 
-	// [currentStateLock] is required to allow concurrent access to address nonces
-	// and balances during reorgs and gossip handling.
-	currentStateLock sync.Mutex
 	// closed when the transaction pool is stopped. Any goroutine can listen
 	// to this to be notified if it should shut down.
 	generalShutdownChan chan struct{}
@@ -685,9 +682,6 @@ func (pool *LegacyPool) validateTxBasics(tx *types.Transaction, local bool) erro
 // validateTx checks whether a transaction is valid according to the consensus
 // rules and adheres to some heuristic limits of the local node (price and size).
 func (pool *LegacyPool) validateTx(tx *types.Transaction, local bool) error {
-	pool.currentStateLock.Lock()
-	defer pool.currentStateLock.Unlock()
-
 	opts := &txpool.ValidationOptionsWithState{
 		State: pool.currentState,
 		Rules: pool.chainconfig.Rules(
@@ -1500,9 +1494,7 @@ func (pool *LegacyPool) reset(oldHead, newHead *types.Header) {
 		return
 	}
 	pool.currentHead.Store(newHead)
-	pool.currentStateLock.Lock()
 	pool.currentState = statedb
-	pool.currentStateLock.Unlock()
 	pool.pendingNonces = newNoncer(statedb)
 
 	// Inject any transactions discarded due to reorgs
@@ -1515,9 +1507,6 @@ func (pool *LegacyPool) reset(oldHead, newHead *types.Header) {
 // future queue to the set of pending transactions. During this process, all
 // invalidated transactions (low nonce, low balance) are deleted.
 func (pool *LegacyPool) promoteExecutables(accounts []common.Address) []*types.Transaction {
-	pool.currentStateLock.Lock()
-	defer pool.currentStateLock.Unlock()
-
 	// Track the promoted transactions to broadcast them at once
 	var promoted []*types.Transaction
 
@@ -1724,9 +1713,6 @@ func (pool *LegacyPool) truncateQueue() {
 // is always explicitly triggered by SetBaseFee and it would be unnecessary and wasteful
 // to trigger a re-heap is this function
 func (pool *LegacyPool) demoteUnexecutables() {
-	pool.currentStateLock.Lock()
-	defer pool.currentStateLock.Unlock()
-
 	// Iterate over all accounts and demote any non-executable transactions
 	gasLimit := pool.currentHead.Load().GasLimit
 	for addr, list := range pool.pending {