Simplified code in various places (#6176)

All these changes should have no side-effects or change behavior:

- Use bytes.Buffer's String() instead of a conversion
- Use time.Since and time.Until where fitting
- Drop unnecessary returns and assignment

agent/agent_endpoint.go

@@ -141,7 +141,7 @@ func (s *HTTPServer) AgentReload(resp http.ResponseWriter, req *http.Request) (i
 	}
 
 	// Trigger the reload
-	errCh := make(chan error, 0)
+	errCh := make(chan error)
 	select {
 	case <-s.agent.shutdownCh:
 		return nil, fmt.Errorf("Agent was shutdown before reload could be completed")

agent/agent_endpoint_test.go

@@ -532,7 +532,7 @@ func TestAgent_Service(t *testing.T) {
 			}
 			start := time.Now()
 			obj, err := a.srv.AgentService(resp, req)
-			elapsed := time.Now().Sub(start)
+			elapsed := time.Since(start)
 
 			if tt.wantErr != "" {
 				require.Error(err)
@@ -5298,7 +5298,7 @@ func TestAgentConnectProxyConfig_Blocking(t *testing.T) {
 			}
 			start := time.Now()
 			obj, err := a.srv.AgentConnectProxyConfig(resp, req)
-			elapsed := time.Now().Sub(start)
+			elapsed := time.Since(start)
 
 			if tt.wantErr {
 				require.Error(err)

agent/cache/cache.go

@@ -703,7 +703,7 @@ func (c *Cache) runExpiryLoop() {
 		c.entriesLock.RLock()
 		if len(c.entriesExpiryHeap.Entries) > 0 {
 			entry = c.entriesExpiryHeap.Entries[0]
-			expiryTimer = time.NewTimer(entry.Expires.Sub(time.Now()))
+			expiryTimer = time.NewTimer(time.Until(entry.Expires))
 			expiryCh = expiryTimer.C
 		}
 		c.entriesLock.RUnlock()

agent/catalog_endpoint.go

@@ -151,7 +151,7 @@ RETRY_ONCE:
 
 	// Use empty map instead of nil
 	if out.Services == nil {
-		out.Services = make(structs.Services, 0)
+		out.Services = make(structs.Services)
 	}
 	metrics.IncrCounterWithLabels([]string{"client", "api", "success", "catalog_services"}, 1,
 		[]metrics.Label{{Name: "node", Value: s.nodeName()}})

agent/connect/ca/provider_consul_test.go

@@ -178,7 +178,7 @@ func TestConsulCAProvider_SignLeaf(t *testing.T) {
 		require.Equal(parsed.SerialNumber.Uint64(), uint64(2))
 
 		// Ensure the cert is valid now and expires within the correct limit.
-		require.True(parsed.NotAfter.Sub(time.Now()) < 3*24*time.Hour)
+		require.True(time.Until(parsed.NotAfter) < 3*24*time.Hour)
 		require.True(parsed.NotBefore.Before(time.Now()))
 	}
 

agent/connect/ca/provider_vault_test.go

@@ -186,7 +186,7 @@ func TestVaultCAProvider_SignLeaf(t *testing.T) {
 		require.NotEqual(firstSerial, parsed.SerialNumber.Uint64())
 
 		// Ensure the cert is valid now and expires within the correct limit.
-		require.True(parsed.NotAfter.Sub(time.Now()) < time.Hour)
+		require.True(time.Until(parsed.NotAfter) < time.Hour)
 		require.True(parsed.NotBefore.Before(time.Now()))
 	}
 }

agent/consul/acl_replication_types.go

@@ -316,7 +316,7 @@ func (r *aclRoleReplicator) FetchUpdated(srv *Server, updates []string) (int, er
 				delete(keep, role.ID)
 			}
 			missing := make([]string, 0, len(keep))
-			for id, _ := range keep {
+			for id := range keep {
 				missing = append(missing, id)
 			}
 			return 0, fmt.Errorf("role replication trying to replicated uncached roles with IDs: %v", missing)

agent/consul/kvs_endpoint_test.go

@@ -596,11 +596,7 @@ key "zip" {
 		t.Fatalf("err: %v", err)
 	}
 
-	actualKeys = []string{}
-
-	for _, key := range keyList.Keys {
-		actualKeys = append(actualKeys, key)
-	}
+	actualKeys = keyList.Keys
 
 	verify.Values(t, "", actualKeys, expectedKeys)
 

agent/consul/leader.go

@@ -1192,7 +1192,7 @@ func (s *Server) pruneCARoots() error {
 
 	var newRoots structs.CARoots
 	for _, r := range roots {
-		if !r.Active && !r.RotatedOutAt.IsZero() && time.Now().Sub(r.RotatedOutAt) > common.LeafCertTTL*2 {
+		if !r.Active && !r.RotatedOutAt.IsZero() && time.Since(r.RotatedOutAt) > common.LeafCertTTL*2 {
 			s.logger.Printf("[INFO] connect: pruning old unused root CA (ID: %s)", r.ID)
 			continue
 		}

agent/consul/server_lookup.go

@@ -51,8 +51,7 @@ func (sl *ServerLookup) ServerAddr(id raft.ServerID) (raft.ServerAddress, error)
 func (sl *ServerLookup) Server(addr raft.ServerAddress) *metadata.Server {
 	sl.lock.RLock()
 	defer sl.lock.RUnlock()
-	svr, _ := sl.addressToServer[addr]
-	return svr
+	return sl.addressToServer[addr]
 }
 
 func (sl *ServerLookup) Servers() []*metadata.Server {

agent/consul/server_test.go

@@ -820,7 +820,6 @@ func TestServer_BadExpect(t *testing.T) {
 type fakeGlobalResp struct{}
 
 func (r *fakeGlobalResp) Add(interface{}) {
-	return
 }
 
 func (r *fakeGlobalResp) New() interface{} {

agent/consul/state/acl_test.go

@@ -3824,11 +3824,11 @@ func stripIrrelevantTokenFields(token *structs.ACLToken) *structs.ACLToken {
 	// When comparing the tokens disregard the policy link names.  This
 	// data is not cleanly updated in a variety of scenarios and should not
 	// be relied upon.
-	for i, _ := range tokenCopy.Policies {
+	for i := range tokenCopy.Policies {
 		tokenCopy.Policies[i].Name = ""
 	}
 	// Also do the same for Role links.
-	for i, _ := range tokenCopy.Roles {
+	for i := range tokenCopy.Roles {
 		tokenCopy.Roles[i].Name = ""
 	}
 	// The raft indexes won't match either because the requester will not

agent/http.go

@@ -293,7 +293,7 @@ func (s *HTTPServer) handler(enableDebug bool) http.Handler {
 	mux.HandleFunc("/", s.Index)
 	for pattern, fn := range endpoints {
 		thisFn := fn
-		methods, _ := allowedMethods[pattern]
+		methods := allowedMethods[pattern]
 		bound := func(resp http.ResponseWriter, req *http.Request) (interface{}, error) {
 			return thisFn(s, resp, req)
 		}

agent/router/manager.go

@@ -342,8 +342,6 @@ func (m *Manager) RebalanceServers() {
 		// continue to use the existing connection until the next
 		// rebalance occurs.
 	}
-
-	return
 }
 
 // reconcileServerList returns true when the first server in serverList

agent/ui_endpoint_test.go

@@ -60,7 +60,7 @@ func TestUiIndex(t *testing.T) {
 	// Verify the body
 	out := bytes.NewBuffer(nil)
 	io.Copy(out, resp.Body)
-	if string(out.Bytes()) != "test" {
+	if out.String() != "test" {
 		t.Fatalf("bad: %s", out.Bytes())
 	}
 }

command/debug/debug.go

@@ -302,7 +302,7 @@ func (c *cmd) captureStatic() error {
 	var errors error
 
 	// Collect the named outputs here
-	outputs := make(map[string]interface{}, 0)
+	outputs := make(map[string]interface{})
 
 	// Capture host information
 	if c.configuredTarget("host") {

lib/telemetry.go

@@ -225,7 +225,7 @@ func (c *TelemetryConfig) MergeDefaults(defaults *TelemetryConfig) {
 				continue
 			}
 		case reflect.Bool:
-			if f.Bool() != false {
+			if f.Bool() {
 				continue
 			}
 		default:

sdk/testutil/retry/retry.go

@@ -110,7 +110,7 @@ func dedup(a []string) string {
 			delete(m, s)
 		}
 	}
-	return string(b.Bytes())
+	return b.String()
 }
 
 func run(r Retryer, t Failer, f func(r *R)) {