From 015a28338407940217ec89f22b980d9b48580045 Mon Sep 17 00:00:00 2001
From: Marcel Fest <marcel.fest@telekom.de>
Date: Tue, 23 Apr 2024 17:35:46 +0200
Subject: [PATCH] Remove go routines and hidden unlock

---
 pkg/monitoring/collector.go |  1 -
 pkg/monitoring/frr.go       | 24 +++++++++++-------------
 pkg/monitoring/nl.go        | 23 ++++++++++-------------
 3 files changed, 21 insertions(+), 27 deletions(-)

diff --git a/pkg/monitoring/collector.go b/pkg/monitoring/collector.go
index eb18302e..f98e3970 100644
--- a/pkg/monitoring/collector.go
+++ b/pkg/monitoring/collector.go
@@ -55,7 +55,6 @@ type basicCollector struct {
 
 // 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 {
diff --git a/pkg/monitoring/frr.go b/pkg/monitoring/frr.go
index abd2991d..be46462a 100644
--- a/pkg/monitoring/frr.go
+++ b/pkg/monitoring/frr.go
@@ -253,22 +253,20 @@ func (c *frrCollector) Update(ch chan<- prometheus.Metric) error {
 	if len(c.channels) == 1 {
 		c.wg = sync.WaitGroup{}
 		c.wg.Add(1)
-		// 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()
-			// unlock is done after return using defer.
-			defer c.wg.Done()
-			c.updateChannels(vrfs, routes, neighbors)
-		}(routes, neighbors, vrfs)
-		// unlock is done in this function.
-		defer c.clearChannels()
+
+		routes := c.getRoutes()
+		vrfs := c.getVrfs()
+		neighbors := c.getBGPNeighbors()
+
+		c.mu.Lock()
+		c.updateChannels(vrfs, routes, neighbors)
+		c.clearChannels()
+		c.wg.Done()
+		c.mu.Unlock()
 	} else {
 		c.mu.Unlock()
+		c.wg.Wait()
 	}
-	c.wg.Wait()
 	return nil
 }
diff --git a/pkg/monitoring/nl.go b/pkg/monitoring/nl.go
index 078b59f9..cb39c602 100644
--- a/pkg/monitoring/nl.go
+++ b/pkg/monitoring/nl.go
@@ -93,22 +93,19 @@ func (c *netlinkCollector) Update(ch chan<- prometheus.Metric) error {
 	if len(c.channels) == 1 {
 		c.wg = sync.WaitGroup{}
 		c.wg.Add(1)
-		// 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()
-			// unlock is done after return using defer.
-			defer c.wg.Done()
-			c.updateChannels(neighbors, routes)
-		}(routes, neighbors)
-		// unlock is done in this function.
-		defer c.clearChannels()
+
+		routes := c.getRoutes()
+		neighbors := c.getNeighbors()
+
+		c.mu.Lock()
+		c.updateChannels(neighbors, routes)
+		c.clearChannels()
+		c.wg.Done()
+		c.mu.Unlock()
 	} else {
 		c.mu.Unlock()
+		c.wg.Wait()
 	}
-	c.wg.Wait()
 	return nil
 }