implement a prefix logger

internal/utils/log.go

@@ -28,6 +28,7 @@ const logEnv = "QUIC_GO_LOG_LEVEL"
 type Logger interface {
 	SetLogLevel(LogLevel)
 	SetLogTimeFormat(format string)
+	WithPrefix(prefix string) Logger
 	Debug() bool
 
 	Errorf(format string, args ...interface{})
@@ -39,6 +40,8 @@ type Logger interface {
 var DefaultLogger Logger
 
 type defaultLogger struct {
+	prefix string
+
 	logLevel   LogLevel
 	timeFormat string
 }
@@ -79,10 +82,25 @@ func (l *defaultLogger) Errorf(format string, args ...interface{}) {
 }
 
 func (l *defaultLogger) logMessage(format string, args ...interface{}) {
+	var pre string
+
 	if len(l.timeFormat) > 0 {
-		log.Printf(time.Now().Format(l.timeFormat)+" "+format, args...)
-	} else {
-		log.Printf(format, args...)
+		pre = time.Now().Format(l.timeFormat) + " "
+	}
+	if len(l.prefix) > 0 {
+		pre += l.prefix + " "
+	}
+	log.Printf(pre+format, args...)
+}
+
+func (l *defaultLogger) WithPrefix(prefix string) Logger {
+	if len(l.prefix) > 0 {
+		prefix = l.prefix + " " + prefix
+	}
+	return &defaultLogger{
+		logLevel:   l.logLevel,
+		timeFormat: l.timeFormat,
+		prefix:     prefix,
 	}
 }
 

internal/utils/log_test.go

@@ -35,7 +35,7 @@ var _ = Describe("Log", func() {
 		DefaultLogger.Debugf("debug")
 		DefaultLogger.Infof("info")
 		DefaultLogger.Errorf("err")
-		Expect(b.Bytes()).To(Equal([]byte("")))
+		Expect(b.String()).To(BeEmpty())
 	})
 
 	It("log level err", func() {
@@ -43,9 +43,9 @@ var _ = Describe("Log", func() {
 		DefaultLogger.Debugf("debug")
 		DefaultLogger.Infof("info")
 		DefaultLogger.Errorf("err")
-		Expect(b.Bytes()).To(ContainSubstring("err\n"))
-		Expect(b.Bytes()).ToNot(ContainSubstring("info"))
-		Expect(b.Bytes()).ToNot(ContainSubstring("debug"))
+		Expect(b.String()).To(ContainSubstring("err\n"))
+		Expect(b.String()).ToNot(ContainSubstring("info"))
+		Expect(b.String()).ToNot(ContainSubstring("debug"))
 	})
 
 	It("log level info", func() {
@@ -53,9 +53,9 @@ var _ = Describe("Log", func() {
 		DefaultLogger.Debugf("debug")
 		DefaultLogger.Infof("info")
 		DefaultLogger.Errorf("err")
-		Expect(b.Bytes()).To(ContainSubstring("err\n"))
-		Expect(b.Bytes()).To(ContainSubstring("info\n"))
-		Expect(b.Bytes()).ToNot(ContainSubstring("debug"))
+		Expect(b.String()).To(ContainSubstring("err\n"))
+		Expect(b.String()).To(ContainSubstring("info\n"))
+		Expect(b.String()).ToNot(ContainSubstring("debug"))
 	})
 
 	It("log level debug", func() {
@@ -63,16 +63,16 @@ var _ = Describe("Log", func() {
 		DefaultLogger.Debugf("debug")
 		DefaultLogger.Infof("info")
 		DefaultLogger.Errorf("err")
-		Expect(b.Bytes()).To(ContainSubstring("err\n"))
-		Expect(b.Bytes()).To(ContainSubstring("info\n"))
-		Expect(b.Bytes()).To(ContainSubstring("debug\n"))
+		Expect(b.String()).To(ContainSubstring("err\n"))
+		Expect(b.String()).To(ContainSubstring("info\n"))
+		Expect(b.String()).To(ContainSubstring("debug\n"))
 	})
 
 	It("doesn't add a timestamp if the time format is empty", func() {
 		DefaultLogger.SetLogLevel(LogLevelDebug)
 		DefaultLogger.SetLogTimeFormat("")
 		DefaultLogger.Debugf("debug")
-		Expect(b.Bytes()).To(Equal([]byte("debug\n")))
+		Expect(b.String()).To(Equal("debug\n"))
 	})
 
 	It("adds a timestamp", func() {
@@ -80,7 +80,7 @@ var _ = Describe("Log", func() {
 		DefaultLogger.SetLogTimeFormat(format)
 		DefaultLogger.SetLogLevel(LogLevelInfo)
 		DefaultLogger.Infof("info")
-		t, err := time.Parse(format, string(b.Bytes()[:b.Len()-6]))
+		t, err := time.Parse(format, string(b.String()[:b.Len()-6]))
 		Expect(err).ToNot(HaveOccurred())
 		Expect(t).To(BeTemporally("~", time.Now(), 25*time.Hour))
 	})
@@ -91,6 +91,23 @@ var _ = Describe("Log", func() {
 		Expect(DefaultLogger.Debug()).To(BeTrue())
 	})
 
+	It("adds a prefix", func() {
+		DefaultLogger.SetLogLevel(LogLevelDebug)
+		prefixLogger := DefaultLogger.WithPrefix("prefix")
+		prefixLogger.Debugf("debug")
+		Expect(b.String()).To(ContainSubstring("prefix"))
+		Expect(b.String()).To(ContainSubstring("debug"))
+	})
+
+	It("adds multiple prefixes", func() {
+		DefaultLogger.SetLogLevel(LogLevelDebug)
+		prefixLogger := DefaultLogger.WithPrefix("prefix1")
+		prefixPrefixLogger := prefixLogger.WithPrefix("prefix2")
+		prefixPrefixLogger.Debugf("debug")
+		Expect(b.String()).To(ContainSubstring("prefix"))
+		Expect(b.String()).To(ContainSubstring("debug"))
+	})
+
 	Context("reading from env", func() {
 		BeforeEach(func() {
 			Expect(DefaultLogger.(*defaultLogger).logLevel).To(Equal(LogLevelNothing))