use tickers instead of time.After to avoid memory leak (#5220)

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

plugin/azure/azure.go

@@ -84,12 +84,16 @@ func (h *Azure) Run(ctx context.Context) error {
 		return err
 	}
 	go func() {
+		delay := 1 * time.Minute
+		timer := time.NewTimer(delay)
+		defer timer.Stop()
 		for {
+			timer.Reset(delay)
 			select {
 			case <-ctx.Done():
 				log.Debugf("Breaking out of Azure update loop for %v: %v", h.zoneNames, ctx.Err())
 				return
-			case <-time.After(1 * time.Minute):
+			case <-timer.C:
 				if err := h.updateZones(ctx); err != nil && ctx.Err() == nil {
 					log.Errorf("Failed to update zones %v: %v", h.zoneNames, err)
 				}

plugin/clouddns/clouddns.go

@@ -82,12 +82,16 @@ func (h *CloudDNS) Run(ctx context.Context) error {
 		return err
 	}
 	go func() {
+		delay := 1 * time.Minute
+		timer := time.NewTimer(delay)
+		defer timer.Stop()
 		for {
+			timer.Reset(delay)
 			select {
 			case <-ctx.Done():
 				log.Debugf("Breaking out of CloudDNS update loop for %v: %v", h.zoneNames, ctx.Err())
 				return
-			case <-time.After(1 * time.Minute):
+			case <-timer.C:
 				if err := h.updateZones(ctx); err != nil && ctx.Err() == nil /* Don't log error if ctx expired. */ {
 					log.Errorf("Failed to update zones %v: %v", h.zoneNames, err)
 				}

plugin/dnstap/io.go

@@ -92,8 +92,10 @@ func (d *dio) write(payload *tap.Dnstap) error {
 }
 
 func (d *dio) serve() {
-	timeout := time.After(d.flushTimeout)
+	timeout := time.NewTimer(d.flushTimeout)
+	defer timeout.Stop()
 	for {
+		timeout.Reset(d.flushTimeout)
 		select {
 		case <-d.quit:
 			if d.enc == nil {
@@ -106,7 +108,7 @@ func (d *dio) serve() {
 			if err := d.write(&payload); err != nil {
 				d.dial()
 			}
-		case <-timeout:
+		case <-timeout.C:
 			if dropped := atomic.SwapUint32(&d.dropped, 0); dropped > 0 {
 				log.Warningf("Dropped dnstap messages: %d", dropped)
 			}
@@ -115,7 +117,6 @@ func (d *dio) serve() {
 			} else {
 				d.enc.flush()
 			}
-			timeout = time.After(d.flushTimeout)
 		}
 	}
 }

plugin/kubernetes/kubernetes.go

@@ -275,19 +275,25 @@ func (k *Kubernetes) InitKubeCache(ctx context.Context) (onStart func() error, o
 			k.APIConn.Run()
 		}()
 
-		timeout := time.After(5 * time.Second)
-		logWaiting := time.After(500 * time.Millisecond)
-		ticker := time.NewTicker(100 * time.Millisecond)
-		defer ticker.Stop()
+		timeout := 5 * time.Second
+		timeoutTicker := time.NewTicker(timeout)
+		defer timeoutTicker.Stop()
+		logDelay := 500 * time.Millisecond
+		logTicker := time.NewTicker(logDelay)
+		defer logTicker.Stop()
+		checkSyncTicker := time.NewTicker(100 * time.Millisecond)
+		defer checkSyncTicker.Stop()
 		for {
+			timeoutTicker.Reset(timeout)
+			logTicker.Reset(logDelay)
 			select {
-			case <-ticker.C:
+			case <-checkSyncTicker.C:
 				if k.APIConn.HasSynced() {
 					return nil
 				}
-			case <-logWaiting:
+			case <-logTicker.C:
 				log.Info("waiting for Kubernetes API before starting server")
-			case <-timeout:
+			case <-timeoutTicker.C:
 				log.Warning("starting server with unsynced Kubernetes API")
 				return nil
 			}

plugin/route53/route53.go

@@ -84,12 +84,15 @@ func (h *Route53) Run(ctx context.Context) error {
 		return err
 	}
 	go func() {
+		timer := time.NewTimer(h.refresh)
+		defer timer.Stop()
 		for {
+			timer.Reset(h.refresh)
 			select {
 			case <-ctx.Done():
 				log.Debugf("Breaking out of Route53 update loop for %v: %v", h.zoneNames, ctx.Err())
 				return
-			case <-time.After(h.refresh):
+			case <-timer.C:
 				if err := h.updateZones(ctx); err != nil && ctx.Err() == nil /* Don't log error if ctx expired. */ {
 					log.Errorf("Failed to update zones %v: %v", h.zoneNames, err)
 				}