fixed race condition reported in issue #881

p2p/trust/trustmetric.go

@@ -144,6 +144,7 @@ func (tms *TrustMetricStore) loadFromDB() bool {
 	for key, p := range peers {
 		tm := NewMetricWithConfig(tms.config)
 
+		tm.mtx.Lock()
 		// Restore the number of time intervals we have previously tracked
 		if p.NumIntervals > tm.maxIntervals {
 			p.NumIntervals = tm.maxIntervals
@@ -168,6 +169,8 @@ func (tms *TrustMetricStore) loadFromDB() bool {
 		}
 		// Calculate the history value based on the loaded history data
 		tm.historyValue = tm.calcHistoryValue()
+		tm.mtx.Unlock()
+
 		// Load the peer trust metric into the store
 		tms.peerMetrics[key] = tm
 	}
@@ -181,11 +184,13 @@ func (tms *TrustMetricStore) saveToDB() {
 	peers := make(map[string]peerHistoryJSON, 0)
 
 	for key, tm := range tms.peerMetrics {
+		tm.mtx.Lock()
 		// Add an entry for the peer identified by key
 		peers[key] = peerHistoryJSON{
 			NumIntervals: tm.numIntervals,
 			History:      tm.history,
 		}
+		tm.mtx.Unlock()
 	}
 
 	// Write all the data back to the DB
@@ -236,6 +241,9 @@ const (
 // TrustMetric - keeps track of peer reliability
 // See tendermint/docs/architecture/adr-006-trust-metric.md for details
 type TrustMetric struct {
+	// Mutex that protects the metric from concurrent access
+	mtx sync.Mutex
+
 	// Determines the percentage given to current behavior
 	proportionalWeight float64
 
@@ -277,24 +285,6 @@ type TrustMetric struct {
 
 	// Sending true on this channel stops tracking, while false pauses tracking
 	stop chan bool
-
-	// For sending information about new good/bad events to be recorded
-	update chan *updateBadGood
-
-	// The channel to request a newly calculated trust value
-	trustValue chan *reqTrustValue
-}
-
-// For the TrustMetric update channel
-type updateBadGood struct {
-	IsBad bool
-	Add   int
-}
-
-// For the TrustMetric trustValue channel
-type reqTrustValue struct {
-	// The requested trust value is sent back on this channel
-	Resp chan float64
 }
 
 // Pause tells the metric to pause recording data over time intervals.
@@ -310,20 +300,44 @@ func (tm *TrustMetric) Stop() {
 
 // BadEvents indicates that an undesirable event(s) took place
 func (tm *TrustMetric) BadEvents(num int) {
-	tm.update <- &updateBadGood{IsBad: true, Add: num}
+	tm.mtx.Lock()
+	defer tm.mtx.Unlock()
+
+	// Check if this is the first experience with
+	// what we are tracking since being paused
+	if tm.paused {
+		tm.good = 0
+		tm.bad = 0
+		// New events cause us to unpause the metric
+		tm.paused = false
+	}
+
+	tm.bad += float64(num)
 }
 
 // GoodEvents indicates that a desirable event(s) took place
 func (tm *TrustMetric) GoodEvents(num int) {
-	tm.update <- &updateBadGood{IsBad: false, Add: num}
+	tm.mtx.Lock()
+	defer tm.mtx.Unlock()
+
+	// Check if this is the first experience with
+	// what we are tracking since being paused
+	if tm.paused {
+		tm.good = 0
+		tm.bad = 0
+		// New events cause us to unpause the metric
+		tm.paused = false
+	}
+
+	tm.good += float64(num)
 }
 
 // TrustValue gets the dependable trust value; always between 0 and 1
 func (tm *TrustMetric) TrustValue() float64 {
-	resp := make(chan float64, 1)
+	tm.mtx.Lock()
+	defer tm.mtx.Unlock()
 
-	tm.trustValue <- &reqTrustValue{Resp: resp}
-	return <-resp
+	return tm.calcTrustValue()
 }
 
 // TrustScore gets a score based on the trust value always between 0 and 100
@@ -381,9 +395,7 @@ func NewMetricWithConfig(tmc TrustMetricConfig) *TrustMetric {
 	tm.historyMaxSize = intervalToHistoryOffset(tm.maxIntervals) + 1
 	// This metric has a perfect history so far
 	tm.historyValue = 1.0
-	// Setup the channels
-	tm.update = make(chan *updateBadGood, defaultUpdateChanCapacity)
-	tm.trustValue = make(chan *reqTrustValue, defaultRequestChanCapacity)
+	// Setup the stop channel
 	tm.stop = make(chan bool, 1)
 
 	go tm.processRequests()
@@ -516,24 +528,8 @@ func (tm *TrustMetric) processRequests() {
 loop:
 	for {
 		select {
-		case bg := <-tm.update:
-			// Check if this is the first experience with
-			// what we are tracking since being paused
-			if tm.paused {
-				tm.good = 0
-				tm.bad = 0
-				// New events cause us to unpause the metric
-				tm.paused = false
-			}
-
-			if bg.IsBad {
-				tm.bad += float64(bg.Add)
-			} else {
-				tm.good += float64(bg.Add)
-			}
-		case rtv := <-tm.trustValue:
-			rtv.Resp <- tm.calcTrustValue()
 		case <-t.C:
+			tm.mtx.Lock()
 			if !tm.paused {
 				// Add the current trust value to the history data
 				newHist := tm.calcTrustValue()
@@ -563,13 +559,17 @@ loop:
 				tm.good = 0
 				tm.bad = 0
 			}
+			tm.mtx.Unlock()
 		case stop := <-tm.stop:
+			tm.mtx.Lock()
 			if stop {
 				// Stop all further tracking for this metric
+				tm.mtx.Unlock()
 				break loop
 			}
 			// Pause the metric for now
 			tm.paused = true
+			tm.mtx.Unlock()
 		}
 	}
 }

p2p/trust/trustmetric_test.go

@@ -210,7 +210,10 @@ func TestTrustMetricStopPause(t *testing.T) {
 	// Give the pause some time to take place
 	time.Sleep(10 * time.Millisecond)
 
+	tm.mtx.Lock()
 	first := tm.numIntervals
+	tm.mtx.Unlock()
+
 	// Allow more time to pass and check the intervals are unchanged
 	time.Sleep(50 * time.Millisecond)
 	assert.Equal(t, first, tm.numIntervals)
@@ -223,7 +226,10 @@ func TestTrustMetricStopPause(t *testing.T) {
 	// Give the stop some time to take place
 	time.Sleep(10 * time.Millisecond)
 
+	tm.mtx.Lock()
 	second := tm.numIntervals
+	tm.mtx.Unlock()
+
 	// Allow more time to pass and check the intervals are unchanged
 	time.Sleep(50 * time.Millisecond)
 	assert.Equal(t, second, tm.numIntervals)