use RWMutex for consensus state

allows multiple RPC requests to query consensus state

Refs #1772

consensus/state.go

@@ -81,7 +81,7 @@ type ConsensusState struct {
 	evpool     sm.EvidencePool
 
 	// internal state
-	mtx sync.Mutex
+	mtx sync.RWMutex
 	cstypes.RoundState
 	state sm.State // State until height-1.
 
@@ -192,15 +192,15 @@ func (cs *ConsensusState) String() string {
 
 // GetState returns a copy of the chain state.
 func (cs *ConsensusState) GetState() sm.State {
-	cs.mtx.Lock()
-	defer cs.mtx.Unlock()
+	cs.mtx.RLock()
+	defer cs.mtx.RUnlock()
 	return cs.state.Copy()
 }
 
 // GetRoundState returns a shallow copy of the internal consensus state.
 func (cs *ConsensusState) GetRoundState() *cstypes.RoundState {
-	cs.mtx.Lock()
-	defer cs.mtx.Unlock()
+	cs.mtx.RLock()
+	defer cs.mtx.RUnlock()
 
 	rs := cs.RoundState // copy
 	return &rs
@@ -208,24 +208,24 @@ func (cs *ConsensusState) GetRoundState() *cstypes.RoundState {
 
 // GetRoundStateJSON returns a json of RoundState, marshalled using go-amino.
 func (cs *ConsensusState) GetRoundStateJSON() ([]byte, error) {
-	cs.mtx.Lock()
-	defer cs.mtx.Unlock()
+	cs.mtx.RLock()
+	defer cs.mtx.RUnlock()
 
 	return cdc.MarshalJSON(cs.RoundState)
 }
 
 // GetRoundStateSimpleJSON returns a json of RoundStateSimple, marshalled using go-amino.
 func (cs *ConsensusState) GetRoundStateSimpleJSON() ([]byte, error) {
-	cs.mtx.Lock()
-	defer cs.mtx.Unlock()
+	cs.mtx.RLock()
+	defer cs.mtx.RUnlock()
 
 	return cdc.MarshalJSON(cs.RoundState.RoundStateSimple())
 }
 
 // GetValidators returns a copy of the current validators.
 func (cs *ConsensusState) GetValidators() (int64, []*types.Validator) {
-	cs.mtx.Lock()
-	defer cs.mtx.Unlock()
+	cs.mtx.RLock()
+	defer cs.mtx.RUnlock()
 	return cs.state.LastBlockHeight, cs.state.Validators.Copy().Validators
 }
 
@@ -245,8 +245,8 @@ func (cs *ConsensusState) SetTimeoutTicker(timeoutTicker TimeoutTicker) {
 
 // LoadCommit loads the commit for a given height.
 func (cs *ConsensusState) LoadCommit(height int64) *types.Commit {
-	cs.mtx.Lock()
-	defer cs.mtx.Unlock()
+	cs.mtx.RLock()
+	defer cs.mtx.RUnlock()
 	if height == cs.blockStore.Height() {
 		return cs.blockStore.LoadSeenCommit(height)
 	}