Always call wg.Add(1) before starting goroutine

While it felt prettier to do both wg.Add(1) and wg.Done() inside the
goroutine functions this is inherently causing a race between starting
the goroutine and the later call to wg.Wait().

While things seems to have worked fine this way lets do it correctly
everywhere to not lead by poor example for future work.

pkg/runner/runner.go

@@ -280,7 +280,6 @@ func (edm *dnstapMinimiser) reverseLabelsBounded(labels []string, maxLen int) []
 
 func (edm *dnstapMinimiser) diskCleaner(wg *sync.WaitGroup, sentDir string) {
 	// We will scan the directory each tick for sent files to remove.
-	wg.Add(1)
 	defer wg.Done()
 
 	ticker := time.NewTicker(time.Second * 60)
@@ -682,15 +681,20 @@ func Run() {
 	labelLimit := 10
 
 	// Start record writers and data senders in the background
+	wg.Add(1)
 	go edm.sessionWriter(dataDir, &wg)
+	wg.Add(1)
 	go edm.histogramWriter(labelLimit, outboxDir, &wg)
 	if !edm.histogramSenderDisabled {
+		wg.Add(1)
 		go edm.histogramSender(outboxDir, sentDir, &wg)
 	}
 	if !edm.mqttDisabled {
+		wg.Add(1)
 		go edm.newQnamePublisher(&wg)
 	}
 
+	wg.Add(1)
 	go edm.diskCleaner(&wg, sentDir)
 
 	dawgFile := viper.GetString("well-known-domains")
@@ -733,6 +737,7 @@ func Run() {
 	}
 
 	// Start data collector
+	wg.Add(1)
 	go edm.dataCollector(&wg, wkdTracker, dawgFile)
 
 	var minimiserWg sync.WaitGroup
@@ -978,7 +983,6 @@ func (wkd *wellKnownDomainsTracker) lookup(ipBytes []byte, msg *dns.Msg) (int, b
 }
 
 func (wkd *wellKnownDomainsTracker) updateRetryer(edm *dnstapMinimiser, wg *sync.WaitGroup) {
-	wg.Add(1)
 	defer wg.Done()
 
 	for wu := range wkd.retryCh {
@@ -1345,7 +1349,6 @@ func (edm *dnstapMinimiser) newSession(dt *dnstap.Dnstap, msg *dns.Msg, isQuery
 }
 
 func (edm *dnstapMinimiser) sessionWriter(dataDir string, wg *sync.WaitGroup) {
-	wg.Add(1)
 	defer wg.Done()
 
 	edm.log.Info("sessionStructWriter: starting")
@@ -1361,7 +1364,6 @@ func (edm *dnstapMinimiser) sessionWriter(dataDir string, wg *sync.WaitGroup) {
 }
 
 func (edm *dnstapMinimiser) histogramWriter(labelLimit int, outboxDir string, wg *sync.WaitGroup) {
-	wg.Add(1)
 	defer wg.Done()
 
 	edm.log.Info("histogramWriter: starting")
@@ -1436,7 +1438,6 @@ func (edm *dnstapMinimiser) createFile(dst string) (*os.File, error) {
 }
 
 func (edm *dnstapMinimiser) histogramSender(outboxDir string, sentDir string, wg *sync.WaitGroup) {
-	wg.Add(1)
 	defer wg.Done()
 
 	edm.log.Info("histogramSender: starting")
@@ -1509,7 +1510,6 @@ func timestampsFromFilename(name string) (time.Time, time.Time, error) {
 }
 
 func (edm *dnstapMinimiser) newQnamePublisher(wg *sync.WaitGroup) {
-	wg.Add(1)
 	defer wg.Done()
 
 	edm.log.Info("newQnamePublisher: starting")
@@ -1918,7 +1918,6 @@ func timeUntilNextMinute() time.Duration {
 
 // runMinimiser generates data and it is collected into datasets here
 func (edm *dnstapMinimiser) dataCollector(wg *sync.WaitGroup, wkd *wellKnownDomainsTracker, dawgFile string) {
-	wg.Add(1)
 	defer wg.Done()
 
 	// Keep track of if we have recorded any dnstap packets in session data
@@ -1927,6 +1926,7 @@ func (edm *dnstapMinimiser) dataCollector(wg *sync.WaitGroup, wkd *wellKnownDoma
 	// Start retryer, handles instances where the received update has a
 	// dawgModTime that is no longer valid becuase it has been rotated.
 	var retryerWg sync.WaitGroup
+	retryerWg.Add(1)
 	go wkd.updateRetryer(edm, &retryerWg)
 
 	sessions := []*sessionData{}