Move emptiness check to the receivers.

main.go

@@ -218,11 +218,9 @@ func (p *prometheus) Serve() {
 	}()
 
 	for samples := range p.unwrittenSamples {
-		if len(samples) > 0 {
-			p.storage.AppendSamples(samples)
-			if p.remoteTSDBQueue != nil {
-				p.remoteTSDBQueue.Queue(samples)
-			}
+		p.storage.AppendSamples(samples)
+		if p.remoteTSDBQueue != nil {
+			p.remoteTSDBQueue.Queue(samples)
 		}
 	}
 

storage/remote/queue_manager.go

@@ -115,6 +115,9 @@ func NewTSDBQueueManager(tsdb TSDBClient, queueCapacity int) *TSDBQueueManager {
 // Queue queues a sample batch to be sent to the TSDB. It drops the most
 // recently queued samples on the floor if the queue is full.
 func (t *TSDBQueueManager) Queue(s clientmodel.Samples) {
+	if len(s) == 0 {
+		return
+	}
 	select {
 	case t.queue <- s:
 	default: