From 92ada55e5ab539ad8a45e22eb8abb2d8035ec312 Mon Sep 17 00:00:00 2001
From: Ethan Buchman <ethan@coinculture.info>
Date: Wed, 9 Aug 2017 14:55:21 -0400
Subject: [PATCH] make conR.FastSync() thread safe

---
 consensus/reactor.go | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/consensus/reactor.go b/consensus/reactor.go
index 801e010ce..27d1537ad 100644
--- a/consensus/reactor.go
+++ b/consensus/reactor.go
@@ -29,9 +29,11 @@ const (
 type ConsensusReactor struct {
 	p2p.BaseReactor // BaseService + p2p.Switch
 
-	conS     *ConsensusState
+	conS *ConsensusState
+	evsw types.EventSwitch
+
+	mtx      sync.RWMutex
 	fastSync bool
-	evsw     types.EventSwitch
 }
 
 func NewConsensusReactor(consensusState *ConsensusState, fastSync bool) *ConsensusReactor {
@@ -44,14 +46,14 @@ func NewConsensusReactor(consensusState *ConsensusState, fastSync bool) *Consens
 }
 
 func (conR *ConsensusReactor) OnStart() error {
-	conR.Logger.Info("ConsensusReactor ", "fastSync", conR.fastSync)
+	conR.Logger.Info("ConsensusReactor ", "fastSync", conR.FastSync())
 	conR.BaseReactor.OnStart()
 
 	// callbacks for broadcasting new steps and votes to peers
 	// upon their respective events (ie. uses evsw)
 	conR.registerEventCallbacks()
 
-	if !conR.fastSync {
+	if !conR.FastSync() {
 		_, err := conR.conS.Start()
 		if err != nil {
 			return err
@@ -73,7 +75,11 @@ func (conR *ConsensusReactor) SwitchToConsensus(state *sm.State) {
 	// NOTE: The line below causes broadcastNewRoundStepRoutine() to
 	// broadcast a NewRoundStepMessage.
 	conR.conS.updateToState(state)
+
+	conR.mtx.Lock()
 	conR.fastSync = false
+	conR.mtx.Unlock()
+
 	conR.conS.Start()
 }
 
@@ -124,7 +130,7 @@ func (conR *ConsensusReactor) AddPeer(peer *p2p.Peer) {
 
 	// Send our state to peer.
 	// If we're fast_syncing, broadcast a RoundStepMessage later upon SwitchToConsensus().
-	if !conR.fastSync {
+	if !conR.FastSync() {
 		conR.sendNewRoundStepMessages(peer)
 	}
 }
@@ -204,7 +210,7 @@ func (conR *ConsensusReactor) Receive(chID byte, src *p2p.Peer, msgBytes []byte)
 		}
 
 	case DataChannel:
-		if conR.fastSync {
+		if conR.FastSync() {
 			conR.Logger.Info("Ignoring message received during fastSync", "msg", msg)
 			return
 		}
@@ -222,7 +228,7 @@ func (conR *ConsensusReactor) Receive(chID byte, src *p2p.Peer, msgBytes []byte)
 		}
 
 	case VoteChannel:
-		if conR.fastSync {
+		if conR.FastSync() {
 			conR.Logger.Info("Ignoring message received during fastSync", "msg", msg)
 			return
 		}
@@ -244,7 +250,7 @@ func (conR *ConsensusReactor) Receive(chID byte, src *p2p.Peer, msgBytes []byte)
 		}
 
 	case VoteSetBitsChannel:
-		if conR.fastSync {
+		if conR.FastSync() {
 			conR.Logger.Info("Ignoring message received during fastSync", "msg", msg)
 			return
 		}
@@ -292,6 +298,8 @@ func (conR *ConsensusReactor) SetEventSwitch(evsw types.EventSwitch) {
 
 // FastSync returns whether the consensus reactor is currently fast syncing
 func (conR *ConsensusReactor) FastSync() bool {
+	conR.mtx.RLock()
+	defer conR.mtx.RUnlock()
 	return conR.fastSync
 }