try to fix akward behaviour on parallel http calls

pkg/monitoring/collector.go

@@ -53,7 +53,9 @@ type basicCollector struct {
 	logger   logr.Logger
 }
 
+// only use with Lock called before
 func (c *basicCollector) clearChannels() {
+	defer c.mu.Unlock()
 	c.channels = []chan<- prometheus.Metric{}
 }
 func (d *typedFactoryDesc) mustNewConstMetric(value float64, labels ...string) prometheus.Metric {

pkg/monitoring/frr.go

@@ -253,18 +253,22 @@ func (c *frrCollector) Update(ch chan<- prometheus.Metric) error {
 	if len(c.channels) == 1 {
 		c.wg = sync.WaitGroup{}
 		c.wg.Add(1)
-		go func() {
-			defer c.wg.Done()
-			vrfs := c.getVrfs()
-			neighbors := c.getBGPNeighbors()
-			routes := c.getRoutes()
+		// Ensure all other function calls will wait
+		c.mu.Unlock()
+		routes, neighbors, vrfs := func() ([]route.Information, frr.BGPVrfSummary, []frr.VrfVniSpec) {
+			return c.getRoutes(), c.getBGPNeighbors(), c.getVrfs()
+		}()
+		go func(routes []route.Information, neighbors frr.BGPVrfSummary, vrfs []frr.VrfVniSpec) {
 			c.mu.Lock()
-			defer c.mu.Unlock()
+			// unlock is done after return using defer
+			defer c.wg.Done()
 			c.updateChannels(vrfs, routes, neighbors)
-			c.clearChannels()
-		}()
+		}(routes, neighbors, vrfs)
+		// unlock is done in this function.
+		defer c.clearChannels()
+	} else {
+		c.mu.Unlock()
 	}
-	c.mu.Unlock()
 	c.wg.Wait()
 	return nil
 }

pkg/monitoring/nl.go

@@ -93,17 +93,22 @@ func (c *netlinkCollector) Update(ch chan<- prometheus.Metric) error {
 	if len(c.channels) == 1 {
 		c.wg = sync.WaitGroup{}
 		c.wg.Add(1)
-		go func() {
-			defer c.wg.Done()
-			routes := c.getRoutes()
-			neighbors := c.getNeighbors()
+		// Ensure all other function calls will wait
+		c.mu.Unlock()
+		routes, neighbors := func() ([]route.Information, []nl.NeighborInformation) {
+			return c.getRoutes(), c.getNeighbors()
+		}()
+		go func(routes []route.Information, neighbors []nl.NeighborInformation) {
 			c.mu.Lock()
-			defer c.mu.Unlock()
+			// unlock is done after return using defer
+			defer c.wg.Done()
 			c.updateChannels(neighbors, routes)
-			c.clearChannels()
-		}()
+		}(routes, neighbors)
+		// unlock is done in this function.
+		defer c.clearChannels()
+	} else {
+		c.mu.Unlock()
 	}
-	c.mu.Unlock()
 	c.wg.Wait()
 	return nil
 }