From 8f80cafa108cf0a762e0e34a6a4cd04021139bd1 Mon Sep 17 00:00:00 2001
From: gary rong <garyrong0905@gmail.com>
Date: Wed, 17 Jul 2019 18:39:41 +0800
Subject: core: fix write concurrency in txpool (#19835)

* core: fix write coucurrency in txpool

* core: add rlock for pendingState read access

* core: address comments
---
 core/tx_noncer.go | 26 ++++++++++++++++++++++++++
 core/tx_pool.go   | 12 +++---------
 2 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/core/tx_noncer.go b/core/tx_noncer.go
index 98a78e087..aa87c643a 100644
--- a/core/tx_noncer.go
+++ b/core/tx_noncer.go
@@ -17,6 +17,8 @@
 package core
 
 import (
+	"sync"
+
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/state"
 )
@@ -27,6 +29,7 @@ import (
 type txNoncer struct {
 	fallback *state.StateDB
 	nonces   map[common.Address]uint64
+	lock     sync.Mutex
 }
 
 // newTxNoncer creates a new virtual state database to track the pool nonces.
@@ -40,6 +43,11 @@ func newTxNoncer(statedb *state.StateDB) *txNoncer {
 // get returns the current nonce of an account, falling back to a real state
 // database if the account is unknown.
 func (txn *txNoncer) get(addr common.Address) uint64 {
+	// We use mutex for get operation is the underlying
+	// state will mutate db even for read access.
+	txn.lock.Lock()
+	defer txn.lock.Unlock()
+
 	if _, ok := txn.nonces[addr]; !ok {
 		txn.nonces[addr] = txn.fallback.GetNonce(addr)
 	}
@@ -49,5 +57,23 @@ func (txn *txNoncer) get(addr common.Address) uint64 {
 // set inserts a new virtual nonce into the virtual state database to be returned
 // whenever the pool requests it instead of reaching into the real state database.
 func (txn *txNoncer) set(addr common.Address, nonce uint64) {
+	txn.lock.Lock()
+	defer txn.lock.Unlock()
+
+	txn.nonces[addr] = nonce
+}
+
+// setIfLower updates a new virtual nonce into the virtual state database if the
+// the new one is lower.
+func (txn *txNoncer) setIfLower(addr common.Address, nonce uint64) {
+	txn.lock.Lock()
+	defer txn.lock.Unlock()
+
+	if _, ok := txn.nonces[addr]; !ok {
+		txn.nonces[addr] = txn.fallback.GetNonce(addr)
+	}
+	if txn.nonces[addr] <= nonce {
+		return
+	}
 	txn.nonces[addr] = nonce
 }
diff --git a/core/tx_pool.go b/core/tx_pool.go
index 43caf16b1..c41d3fbd4 100644
--- a/core/tx_pool.go
+++ b/core/tx_pool.go
@@ -854,9 +854,7 @@ func (pool *TxPool) removeTx(hash common.Hash, outofbound bool) {
 				pool.enqueueTx(tx.Hash(), tx)
 			}
 			// Update the account nonce if needed
-			if nonce := tx.Nonce(); pool.pendingNonces.get(addr) > nonce {
-				pool.pendingNonces.set(addr, nonce)
-			}
+			pool.pendingNonces.setIfLower(addr, tx.Nonce())
 			// Reduce the pending counter
 			pendingCounter.Dec(int64(1 + len(invalids)))
 			return
@@ -1232,9 +1230,7 @@ func (pool *TxPool) truncatePending() {
 						pool.all.Remove(hash)
 
 						// Update the account nonce to the dropped transaction
-						if nonce := tx.Nonce(); pool.pendingNonces.get(offenders[i]) > nonce {
-							pool.pendingNonces.set(offenders[i], nonce)
-						}
+						pool.pendingNonces.setIfLower(offenders[i], tx.Nonce())
 						log.Trace("Removed fairness-exceeding pending transaction", "hash", hash)
 					}
 					pool.priced.Removed(len(caps))
@@ -1261,9 +1257,7 @@ func (pool *TxPool) truncatePending() {
 					pool.all.Remove(hash)
 
 					// Update the account nonce to the dropped transaction
-					if nonce := tx.Nonce(); pool.pendingNonces.get(addr) > nonce {
-						pool.pendingNonces.set(addr, nonce)
-					}
+					pool.pendingNonces.setIfLower(addr, tx.Nonce())
 					log.Trace("Removed fairness-exceeding pending transaction", "hash", hash)
 				}
 				pool.priced.Removed(len(caps))
-- 
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