Linting fixes.

.golangci.yml

@@ -12,8 +12,8 @@ linters:
 linters-settings:
   lll:
     line-length: 120
-  gocyclo:
-    min-complexity: 40
+  cyclop:
+    max-complexity: 40
   gocognit:
     min-complexity: 40
   funlen:

cmd/metricator-client/main.go

@@ -25,6 +25,9 @@ var (
 	output            = flag.String("output", "json", "Output format. Can be 'json' or 'plain-by-line'.")
 )
 
+// This function uses fmt.Println to print lines without timestamps to make it easy
+// to parse output, so:
+// nolint:forbidigo
 func main() {
 	config := configuration.NewConfig()
 
@@ -83,17 +86,17 @@ func main() {
 		Timeout: *metricatorTimeout,
 	}
 
-	c := client.NewClient(clientConfig, logger)
+	clnt := client.NewClient(clientConfig, logger)
 
 	var data interface{}
 
 	switch {
 	case *appsList:
-		data = c.GetAppsList()
+		data = clnt.GetAppsList()
 	case *metricsList:
-		data = c.GetMetricsList(*application)
+		data = clnt.GetMetricsList(*application)
 	case *metric != "":
-		data = c.GetMetric(*application, *metric)
+		data = clnt.GetMetric(*application, *metric)
 	}
 
 	switch *output {

cmd/metricatord/main.go

@@ -29,8 +29,7 @@ func main() {
 	// Parse configuration.
 	flag.Parse()
 
-	err := config.Parse()
-	if err != nil {
+	if err := config.Parse(); err != nil {
 		log.Fatalln("Failed to parse configuration:", err.Error())
 	}
 

internal/application/application.go

@@ -28,16 +28,18 @@ type Application struct {
 
 // NewApplication creates new application.
 func NewApplication(ctx context.Context, name string, config *Config, logger *logger.Logger) *Application {
-	a := &Application{
+	// Some variables are initialized in initialize() function.
+	// nolint:exhaustivestruct
+	app := &Application{
 		config:   config,
 		ctx:      ctx,
 		doneChan: make(chan struct{}),
 		logger:   logger,
 		name:     name,
 	}
-	a.initialize()
+	app.initialize()
 
-	return a
+	return app
 }
 
 // GetDoneChan returns a channel which should be used to block execution until

internal/application/config.go

@@ -11,5 +11,6 @@ type Config struct {
 	Endpoint string `yaml:"endpoint"`
 	// TimeBetweenRequests is a minimal amount of time which should pass
 	// between requests.
+	// nolint:tagliatelle
 	TimeBetweenRequests time.Duration `yaml:"time_between_requests"`
 }

internal/application/fetcher.go

@@ -10,6 +10,9 @@ func (a *Application) fetch() {
 	// Do not do anything if fetching is running.
 	// ToDo: maybe another approach?
 	a.fetchIsRunningMutex.RLock()
+	// This is an optimization to avoid excessive waiting when using Lock().
+	// Most of time application will wait between fetches.
+	// nolint:ifshort
 	isFetching := a.fetchIsRunning
 	a.fetchIsRunningMutex.RUnlock()
 

internal/application/parser.go

@@ -143,8 +143,8 @@ func (a *Application) getParametersForPrometheusMetric(line string) []string {
 		paramNameFinished, paramValueStarted, paramValueFinished bool
 	)
 
-	for _, r := range valuesString {
-		if paramValueFinished && string(r) == "," {
+	for _, runeChar := range valuesString {
+		if paramValueFinished && string(runeChar) == "," {
 			params = append(params, paramName+":"+paramValue)
 			paramName, paramValue = "", ""
 			paramNameFinished, paramValueStarted, paramValueFinished = false, false, false
@@ -156,8 +156,8 @@ func (a *Application) getParametersForPrometheusMetric(line string) []string {
 		// "deeply nested"? I think not. So:
 		// nolint:nestif
 		if !paramNameFinished {
-			if string(r) != "=" {
-				paramName += string(r)
+			if string(runeChar) != "=" {
+				paramName += string(runeChar)
 
 				continue
 			} else {
@@ -166,19 +166,19 @@ func (a *Application) getParametersForPrometheusMetric(line string) []string {
 				continue
 			}
 		} else {
-			if string(r) == "\"" && !paramValueStarted {
+			if string(runeChar) == "\"" && !paramValueStarted {
 				paramValueStarted = true
 
 				continue
 			}
 
-			if paramValueStarted && string(r) != "\"" {
-				paramValue += string(r)
+			if paramValueStarted && string(runeChar) != "\"" {
+				paramValue += string(runeChar)
 
 				continue
 			}
 
-			if paramValueStarted && string(r) == "\"" {
+			if paramValueStarted && string(runeChar) == "\"" {
 				paramValueFinished = true
 
 				continue

internal/configuration/config.go

@@ -21,16 +21,18 @@ var (
 
 // Config is an application's configuration.
 type Config struct {
-	configPath string
 	// Applications describes configuration for remote application's endpoints.
 	// Key is an application's name.
 	Applications map[string]*application.Config `yaml:"applications"`
 	// Logger is a logging configuration.
-	Logger *logger.Config `yaml:"logger"`
+	Logger     *logger.Config `yaml:"logger"`
+	configPath string
 }
 
 // NewConfig returns new configuration.
 func NewConfig() *Config {
+	// Fields are initialized when parsing YAML file.
+	// nolint:exhaustivestruct
 	c := &Config{}
 	c.initialize()
 

internal/httpserver/handler.go

@@ -48,14 +48,14 @@ func (h *handler) getAppsList() ([]byte, error) {
 
 // Gets request information from URL. Returns a structure with filled request
 // info and error if it occurs.
-func (h *handler) getRequestInfo(r *http.Request) (*models.RequestInfo, error) {
+func (h *handler) getRequestInfo(req *http.Request) (*models.RequestInfo, error) {
 	// Request isn't for API or isn't versioned.
-	if !strings.HasPrefix(r.URL.Path, "/api/v") {
+	if !strings.HasPrefix(req.URL.Path, "/api/v") {
 		return nil, errInvalidPath
 	}
 
 	// Note: first element will always be empty!
-	pathSplitted := strings.Split(r.URL.Path, "/")
+	pathSplitted := strings.Split(req.URL.Path, "/")
 
 	// Request is for API but not enough items in URL was passed.
 	if len(pathSplitted) < 4 {
@@ -119,20 +119,20 @@ func (h *handler) register(appName string, hndl common.HTTPHandlerFunc) {
 }
 
 // ServeHTTP handles every HTTP request.
-func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+func (h *handler) ServeHTTP(writer http.ResponseWriter, req *http.Request) {
 	startTime := time.Now()
 
 	defer func() {
 		requestDuration := time.Since(startTime)
 
-		log.Printf("[HTTP Request] from %s to %s, duration %.4fs\n", r.RemoteAddr, r.URL.Path, requestDuration.Seconds())
+		log.Printf("[HTTP Request] from %s to %s, duration %.4fs\n", req.RemoteAddr, req.URL.Path, requestDuration.Seconds())
 	}()
 
 	// Validate request and extract needed info.
-	rInfo, err := h.getRequestInfo(r)
+	rInfo, err := h.getRequestInfo(req)
 	if err != nil {
-		w.WriteHeader(http.StatusBadRequest)
-		_, _ = w.Write([]byte("400 bad request - " + err.Error()))
+		writer.WriteHeader(http.StatusBadRequest)
+		_, _ = writer.Write([]byte("400 bad request - " + err.Error()))
 
 		return
 	}
@@ -144,14 +144,14 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	case "apps_list":
 		appsList, err := h.getAppsList()
 		if err != nil {
-			w.WriteHeader(http.StatusBadRequest)
-			_, _ = w.Write([]byte("400 bad request - " + err.Error()))
+			writer.WriteHeader(http.StatusBadRequest)
+			_, _ = writer.Write([]byte("400 bad request - " + err.Error()))
 
 			return
 		}
 
-		w.WriteHeader(http.StatusOK)
-		_, _ = w.Write(appsList)
+		writer.WriteHeader(http.StatusOK)
+		_, _ = writer.Write(appsList)
 
 		return
 	case "info":
@@ -169,15 +169,15 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 		infoBytes, _ := json.Marshal(infoData)
 
-		w.WriteHeader(http.StatusOK)
-		_, _ = w.Write(infoBytes)
+		writer.WriteHeader(http.StatusOK)
+		_, _ = writer.Write(infoBytes)
 
 		return
 	case "metrics":
 		handler, found := h.handlers[rInfo.Application]
 		if !found {
-			w.WriteHeader(http.StatusBadRequest)
-			_, _ = w.Write([]byte("400 bad request - " + errInvalidApplication.Error()))
+			writer.WriteHeader(http.StatusBadRequest)
+			_, _ = writer.Write([]byte("400 bad request - " + errInvalidApplication.Error()))
 
 			return
 		}
@@ -185,16 +185,16 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		// Get data from handler.
 		data := handler(rInfo)
 		if data == "" {
-			w.WriteHeader(http.StatusBadRequest)
-			_, _ = w.Write([]byte("400 bad request - " + errNoData.Error()))
+			writer.WriteHeader(http.StatusBadRequest)
+			_, _ = writer.Write([]byte("400 bad request - " + errNoData.Error()))
 		}
 
-		w.WriteHeader(http.StatusOK)
-		_, _ = w.Write([]byte(data))
+		writer.WriteHeader(http.StatusOK)
+		_, _ = writer.Write([]byte(data))
 
 		return
 	}
 
-	w.WriteHeader(http.StatusBadRequest)
-	_, _ = w.Write([]byte("400 bad request - " + errInvalidPath.Error()))
+	writer.WriteHeader(http.StatusBadRequest)
+	_, _ = writer.Write([]byte("400 bad request - " + errInvalidPath.Error()))
 }

internal/httpserver/httpserver.go

@@ -25,15 +25,16 @@ type HTTPServer struct {
 // NewHTTPServer creates HTTP server and executes preliminary initialization
 // (HTTP server structure initialized but it doesn't start).
 func NewHTTPServer(ctx context.Context, cfg *configuration.Config, logger *logger.Logger) (*HTTPServer, chan struct{}) {
-	h := &HTTPServer{
+	// nolint:exhaustivestruct
+	httpServer := &HTTPServer{
 		config:   cfg,
 		ctx:      ctx,
 		doneChan: make(chan struct{}),
 		logger:   logger,
 	}
-	h.initialize()
+	httpServer.initialize()
 
-	return h, h.doneChan
+	return httpServer, httpServer.doneChan
 }
 
 // Returns request's context based on main context of application.

internal/storage/memory/memory.go

@@ -14,25 +14,27 @@ var ErrMetricNotFound = errors.New("metric not found")
 
 // Storage is an in-memory storage.
 type Storage struct {
+	dataMutex sync.RWMutex
 	ctx       context.Context
 	doneChan  chan struct{}
 	logger    *logger.Logger
 	data      map[string]schema.Metric
 	name      string
-	dataMutex sync.RWMutex
 }
 
 // NewStorage creates new in-memory storage to use.
 func NewStorage(ctx context.Context, name string, logger *logger.Logger) (*Storage, chan struct{}) {
-	s := &Storage{
+	// nolint:exhaustivestruct
+	storage := &Storage{
 		ctx:      ctx,
 		doneChan: make(chan struct{}),
 		logger:   logger,
 		name:     name,
+		data:     make(map[string]schema.Metric),
 	}
-	s.initialize()
+	storage.initialize()
 
-	return s, s.doneChan
+	return storage, storage.doneChan
 }
 
 // Get returns data from storage by key.

pkg/client/client.go

@@ -23,13 +23,14 @@ type Client struct {
 
 // NewClient creates new Metricator client.
 func NewClient(config *Config, logger *logger.Logger) *Client {
-	c := &Client{
+	// nolint:exhaustivestruct
+	client := &Client{
 		config: config,
 		logger: logger,
 	}
-	c.initialize()
+	client.initialize()
 
-	return c
+	return client
 }
 
 // Executes request and parses it's contents.

pkg/schema/metric.go

@@ -18,7 +18,7 @@ type Metric struct {
 
 // NewMetric creates new structure for storing single metric data.
 func NewMetric(name, mType, description string, params []string) Metric {
-	m := Metric{
+	metric := Metric{
 		BaseName:    name,
 		Name:        name,
 		Description: description,
@@ -27,7 +27,7 @@ func NewMetric(name, mType, description string, params []string) Metric {
 		Value:       "",
 	}
 
-	return m
+	return metric
 }
 
 // GetValue returns metric's value.