General simplifications (#3887)

Another try as in #1516

cmd/prometheus/main.go

@@ -420,10 +420,7 @@ func main() {
 				// it needs to read a valid config for each job.
 				// It depends on the config being in sync with the discovery manager so
 				// we wait until the config is fully loaded.
-				select {
-				case <-reloadReady.C:
-					break
-				}
+				<-reloadReady.C
 
 				err := scrapeManager.Run(discoveryManagerScrape.SyncCh())
 				level.Info(logger).Log("msg", "Scrape manager stopped")
@@ -445,10 +442,7 @@ func main() {
 		cancel := make(chan struct{})
 		g.Add(
 			func() error {
-				select {
-				case <-reloadReady.C:
-					break
-				}
+				<-reloadReady.C
 
 				for {
 					select {
@@ -573,10 +567,8 @@ func main() {
 				// it needs to read a valid config for each job.
 				// It depends on the config being in sync with the discovery manager
 				// so we wait until the config is fully loaded.
-				select {
-				case <-reloadReady.C:
-					break
-				}
+				<-reloadReady.C
+
 				notifier.Run(discoveryManagerNotify.SyncCh())
 				level.Info(logger).Log("msg", "Notifier manager stopped")
 				return nil

discovery/kubernetes/node_test.go

@@ -65,7 +65,6 @@ func (i *fakeInformer) GetController() cache.Controller {
 }
 
 func (i *fakeInformer) Run(stopCh <-chan struct{}) {
-	return
 }
 
 func (i *fakeInformer) HasSynced() bool {

discovery/manager.go

@@ -90,13 +90,11 @@ type Manager struct {
 
 // Run starts the background processing
 func (m *Manager) Run() error {
-	for {
-		select {
-		case <-m.ctx.Done():
-			m.cancelDiscoverers()
-			return m.ctx.Err()
-		}
+	for range m.ctx.Done() {
+		m.cancelDiscoverers()
+		return m.ctx.Err()
 	}
+	return nil
 }
 
 // SyncCh returns a read only channel used by all Discoverers to send target updates.

discovery/manager_test.go

@@ -750,7 +750,7 @@ scrape_configs:
 	}
 	discoveryManager.ApplyConfig(c)
 
-	_ = <-discoveryManager.SyncCh()
+	<-discoveryManager.SyncCh()
 	verifyPresence(discoveryManager.targets, poolKey{setName: "prometheus", provider: "static/0"}, "{__address__=\"foo:9090\"}", true)
 	verifyPresence(discoveryManager.targets, poolKey{setName: "prometheus", provider: "static/0"}, "{__address__=\"bar:9090\"}", true)
 
@@ -769,7 +769,7 @@ scrape_configs:
 	}
 	discoveryManager.ApplyConfig(c)
 
-	_ = <-discoveryManager.SyncCh()
+	<-discoveryManager.SyncCh()
 	verifyPresence(discoveryManager.targets, poolKey{setName: "prometheus", provider: "static/0"}, "{__address__=\"foo:9090\"}", true)
 	verifyPresence(discoveryManager.targets, poolKey{setName: "prometheus", provider: "static/0"}, "{__address__=\"bar:9090\"}", false)
 }

documentation/examples/remote_storage/remote_storage_adapter/graphite/client.go

@@ -100,11 +100,7 @@ func (c *Client) Write(samples model.Samples) error {
 	}
 
 	_, err = conn.Write(buf.Bytes())
-	if err != nil {
-		return err
-	}
-
-	return nil
+	return err
 }
 
 // Name identifies the client as a Graphite client.

promql/parse.go

@@ -348,7 +348,6 @@ func (p *parser) recover(errp *error) {
 			*errp = e.(error)
 		}
 	}
-	return
 }
 
 // stmt parses any statement.

rules/manager.go

@@ -286,12 +286,12 @@ func (g *Group) copyState(from *Group) {
 	ruleMap := make(map[string][]int, len(from.rules))
 
 	for fi, fromRule := range from.rules {
-		l, _ := ruleMap[fromRule.Name()]
+		l := ruleMap[fromRule.Name()]
 		ruleMap[fromRule.Name()] = append(l, fi)
 	}
 
 	for i, rule := range g.rules {
-		indexes, _ := ruleMap[rule.Name()]
+		indexes := ruleMap[rule.Name()]
 		if len(indexes) == 0 {
 			continue
 		}

scrape/manager.go

@@ -139,9 +139,7 @@ func (m *Manager) DroppedTargets() []*Target {
 	var droppedTargets []*Target
 	for _, p := range m.scrapePools {
 		p.mtx.RLock()
-		for _, tt := range p.droppedTargets {
-			droppedTargets = append(droppedTargets, tt)
-		}
+		droppedTargets = append(droppedTargets, p.droppedTargets...)
 		p.mtx.RUnlock()
 	}
 	return droppedTargets

storage/remote/queue_manager.go

@@ -196,8 +196,7 @@ func NewQueueManager(logger log.Logger, cfg config.QueueConfig, externalLabels m
 // sample on the floor if the queue is full.
 // Always returns nil.
 func (t *QueueManager) Append(s *model.Sample) error {
-	var snew model.Sample
-	snew = *s
+	snew := *s
 	snew.Metric = s.Metric.Clone()
 
 	for ln, lv := range t.externalLabels {

storage/remote/storage.go

@@ -99,8 +99,7 @@ func (s *Storage) ApplyConfig(conf *config.Config) error {
 			return err
 		}
 
-		var q storage.Queryable
-		q = QueryableClient(c)
+		q := QueryableClient(c)
 		q = ExternablLabelsHandler(q, conf.GlobalConfig.ExternalLabels)
 		if len(rrConf.RequiredMatchers) > 0 {
 			q = RequiredMatchersFilter(q, labelsToEqualityMatchers(rrConf.RequiredMatchers))

util/httputil/client_test.go

@@ -157,7 +157,7 @@ func TestNewClientFromConfig(t *testing.T) {
 			},
 			handler: func(w http.ResponseWriter, r *http.Request) {
 				username, password, ok := r.BasicAuth()
-				if ok == false {
+				if !ok {
 					fmt.Fprintf(w, "The Authorization header wasn't set")
 				} else if ExpectedUsername != username {
 					fmt.Fprintf(w, "The expected username (%s) differs from the obtained username (%s).", ExpectedUsername, username)
@@ -336,7 +336,7 @@ func TestBasicAuthRoundTripper(t *testing.T) {
 
 	fakeRoundTripper := testutil.NewRoundTripCheckRequest(func(req *http.Request) {
 		username, password, ok := req.BasicAuth()
-		if ok == false {
+		if !ok {
 			t.Errorf("The Authorization header wasn't set")
 		}
 		if ExpectedUsername != username {

util/stats/stats_test.go

@@ -45,8 +45,7 @@ func TestQueryStatsWithTimers(t *testing.T) {
 	time.Sleep(2 * time.Millisecond)
 	timer.Stop()
 
-	var qs *QueryStats
-	qs = NewQueryStats(tg)
+	qs := NewQueryStats(tg)
 	actual, err := json.Marshal(qs)
 	if err != nil {
 		t.Fatalf("Unexpected error during serialization: %v", err)

util/testutil/error.go

@@ -20,11 +20,7 @@ func ErrorEqual(left, right error) bool {
 	}
 
 	if left != nil && right != nil {
-		if left.Error() == right.Error() {
-			return true
-		}
-
-		return false
+		return left.Error() == right.Error()
 	}
 
 	return false

web/web.go

@@ -346,10 +346,7 @@ func (h *Handler) Ready() {
 // Verifies whether the server is ready or not.
 func (h *Handler) isReady() bool {
 	ready := atomic.LoadUint32(&h.ready)
-	if ready == 0 {
-		return false
-	}
-	return true
+	return ready > 0
 }
 
 // Checks if server is ready, calls f if it is, returns 503 if it is not.