Add some error logging in Listener.Serve(). (#303)

* Add some error logging in Listener.Serve().

* Remove error logging for TCP listener Accept() calls.

* Optimize code.

---------

Co-authored-by: JB <28275108+mochi-co@users.noreply.github.com>

listeners/http_sysinfo.go

@@ -25,6 +25,7 @@ type HTTPStats struct {
 	config  *Config      // configuration values for the listener
 	listen  *http.Server // the http server
 	sysInfo *system.Info // pointers to the server data
+	log     *slog.Logger // server logger
 	end     uint32       // ensure the close methods are only called once
 }
 
@@ -61,7 +62,8 @@ func (l *HTTPStats) Protocol() string {
 }
 
 // Init initializes the listener.
-func (l *HTTPStats) Init(_ *slog.Logger) error {
+func (l *HTTPStats) Init(log *slog.Logger) error {
+	l.log = log
 	mux := http.NewServeMux()
 	mux.HandleFunc("/", l.jsonHandler)
 	l.listen = &http.Server{
@@ -80,10 +82,17 @@ func (l *HTTPStats) Init(_ *slog.Logger) error {
 
 // Serve starts listening for new connections and serving responses.
 func (l *HTTPStats) Serve(establish EstablishFn) {
+
+	var err error
 	if l.listen.TLSConfig != nil {
-		_ = l.listen.ListenAndServeTLS("", "")
+		err = l.listen.ListenAndServeTLS("", "")
 	} else {
-		_ = l.listen.ListenAndServe()
+		err = l.listen.ListenAndServe()
+	}
+
+	// After the listener has been shutdown, no need to print the http.ErrServerClosed error.
+	if err != nil && atomic.LoadUint32(&l.end) == 0 {
+		l.log.Error("failed to serve.", "error", err, "listener", l.id)
 	}
 }
 

listeners/http_sysinfo_test.go

@@ -125,3 +125,28 @@ func TestHTTPStatsServeTLSAndClose(t *testing.T) {
 	time.Sleep(time.Millisecond)
 	l.Close(MockCloser)
 }
+
+func TestHTTPStatsFailedToServe(t *testing.T) {
+	sysInfo := &system.Info{
+		Version: "test",
+	}
+
+	// setup http stats listener
+	l := NewHTTPStats("t1", "wrong_addr", nil, sysInfo)
+	err := l.Init(logger)
+	require.NoError(t, err)
+
+	o := make(chan bool)
+	go func(o chan bool) {
+		l.Serve(MockEstablisher)
+		o <- true
+	}(o)
+
+	<-o
+	// ensure listening is closed
+	var closed bool
+	l.Close(func(id string) {
+		closed = true
+	})
+	require.Equal(t, true, closed)
+}

listeners/websocket.go

@@ -109,12 +109,18 @@ func (l *Websocket) handler(w http.ResponseWriter, r *http.Request) {
 // Serve starts waiting for new Websocket connections, and calls the connection
 // establishment callback for any received.
 func (l *Websocket) Serve(establish EstablishFn) {
+	var err error
 	l.establish = establish
 
 	if l.listen.TLSConfig != nil {
-		_ = l.listen.ListenAndServeTLS("", "")
+		err = l.listen.ListenAndServeTLS("", "")
 	} else {
-		_ = l.listen.ListenAndServe()
+		err = l.listen.ListenAndServe()
+	}
+
+	// After the listener has been shutdown, no need to print the http.ErrServerClosed error.
+	if err != nil && atomic.LoadUint32(&l.end) == 0 {
+		l.log.Error("failed to serve.", "error", err, "listener", l.id)
 	}
 }
 

listeners/websocket_test.go

@@ -92,6 +92,28 @@ func TestWebsocketServeTLSAndClose(t *testing.T) {
 		closed = true
 	})
 	require.Equal(t, true, closed)
+	<-o
+}
+
+func TestWebsocketFailedToServe(t *testing.T) {
+	l := NewWebsocket("t1", "wrong_addr", &Config{
+		TLSConfig: tlsConfigBasic,
+	})
+	err := l.Init(logger)
+	require.NoError(t, err)
+
+	o := make(chan bool)
+	go func(o chan bool) {
+		l.Serve(MockEstablisher)
+		o <- true
+	}(o)
+
+	<-o
+	var closed bool
+	l.Close(func(id string) {
+		closed = true
+	})
+	require.Equal(t, true, closed)
 }
 
 func TestWebsocketUpgrade(t *testing.T) {