fix data races on spammer

packages/transactionspammer/transactionspammer.go

@@ -14,22 +14,24 @@ import (
 )
 
 var spamming = false
+var spammingMutex sync.Mutex
 
-var startMutex sync.Mutex
-
-var shutdownSignal chan int
+var shutdownSignal chan struct{}
+var done chan struct{}
 
 var sentCounter = uint(0)
 
-func Start(tps uint) {
-	startMutex.Lock()
+func init() {
+	shutdownSignal = make(chan struct{})
+	done = make(chan struct{})
+}
 
-	if !spamming {
-		shutdownSignal = make(chan int, 1)
+func Start(tps uint) {
+	spammingMutex.Lock()
+	spamming = true
+	spammingMutex.Unlock()
 
-		func(shutdownSignal chan int) {
 	daemon.BackgroundWorker("Transaction Spammer", func() {
-				for {
 		start := time.Now()
 		totalSentCounter := int64(0)
 
@@ -39,6 +41,7 @@ func Start(tps uint) {
 				return
 
 			case <-shutdownSignal:
+				done <- struct{}{}
 				return
 
 			default:
@@ -69,24 +72,16 @@ func Start(tps uint) {
 				}
 			}
 		}
-				}
 	})
-		}(shutdownSignal)
-
-		spamming = true
-	}
-
-	startMutex.Unlock()
 }
 
 func Stop() {
-	startMutex.Lock()
-
+	spammingMutex.Lock()
 	if spamming {
-		close(shutdownSignal)
-
+		shutdownSignal <- struct{}{}
+		// wait for spammer to be done
+		<-done
 		spamming = false
 	}
-
-	startMutex.Unlock()
+	spammingMutex.Unlock()
 }