Fixes race condition in EventStream

Locks the mutex for reading when getting Length(). Otherwise, a data race can occur. This can happen despite the previous atomic read because writes are non-atomic.

Signed-off-by: Emily Casey <[email protected]>

eventstream/eventstream.go

@@ -111,7 +111,9 @@ func (es *EventStream) Publish(evt interface{}) {
 
 // Returns an integer that represents the current number of subscribers to the stream
 func (es *EventStream) Length() int32 {
-	return atomic.LoadInt32(&es.counter)
+	es.RLock()
+	defer es.RUnlock()
+	return es.counter
 }
 
 // Subscription is returned from the Subscribe function.