fix: loggers created with With() now inherit level changes on the parent

With() copies the Logger struct by value, which gave the wrapped logger its
own independent int64 for the log level. Subsequent SetLevel calls on the
parent had no effect on any wrapped child.

Fix: change the level field to *int64. New loggers allocate a fresh int64;
With() copies the pointer, so parent and all children share the same memory
cell. SetLevel anywhere in the hierarchy is visible everywhere.

Fixes #184

Author: troclaux

logger.go

@@ -29,7 +29,7 @@ type Logger struct {
 
 	isDiscard uint32
 
-	level           int64
+	level           *int64
 	prefix          string
 	timeFunc        TimeFunction
 	timeFormat      string
@@ -58,7 +58,7 @@ func (l *Logger) Log(level Level, msg any, keyvals ...any) {
 	}
 
 	// check if the level is allowed
-	if atomic.LoadInt64(&l.level) > int64(level) {
+	if atomic.LoadInt64(l.level) > int64(level) {
 		return
 	}
 
@@ -233,16 +233,12 @@ func (l *Logger) SetReportCaller(report bool) {
 
 // GetLevel returns the current level.
 func (l *Logger) GetLevel() Level {
-	l.mu.RLock()
-	defer l.mu.RUnlock()
-	return Level(l.level)
+	return Level(atomic.LoadInt64(l.level))
 }
 
 // SetLevel sets the current level.
 func (l *Logger) SetLevel(level Level) {
-	l.mu.Lock()
-	defer l.mu.Unlock()
-	atomic.StoreInt64(&l.level, int64(level))
+	atomic.StoreInt64(l.level, int64(level))
 }
 
 // GetPrefix returns the current prefix.

logger_121.go

@@ -24,7 +24,7 @@ const slogKindGroup = slog.KindGroup
 //
 // Implements slog.Handler.
 func (l *Logger) Enabled(_ context.Context, level slog.Level) bool {
-	return atomic.LoadInt64(&l.level) <= int64(level)
+	return atomic.LoadInt64(l.level) <= int64(level)
 }
 
 // Handle handles the Record. It will only be called if Enabled returns true.

logger_no121.go

@@ -25,7 +25,7 @@ const slogKindGroup = slog.KindGroup
 //
 // Implements slog.Handler.
 func (l *Logger) Enabled(_ context.Context, level slog.Level) bool {
-	return atomic.LoadInt64(&l.level) <= int64(level)
+	return atomic.LoadInt64(l.level) <= int64(level)
 }
 
 // Handle handles the Record. It will only be called if Enabled returns true.

logger_test.go

@@ -287,3 +287,18 @@ func TestCustomLevel(t *testing.T) {
 	l.Logf(level500, "foo")
 	assert.Equal(t, "foo\n", buf.String())
 }
+
+func TestWithInheritsLevel(t *testing.T) {
+	var buf bytes.Buffer
+	l := New(colorprofile.NewWriter(&buf, os.Environ()))
+	l.SetLevel(InfoLevel)
+	l.SetReportTimestamp(false)
+	l.SetReportCaller(false)
+
+	wrapped := l.With("k", "v")
+
+	// Level raised on parent after wrapped logger created — child must see it.
+	l.SetLevel(DebugLevel)
+	wrapped.Debug("debug msg")
+	assert.Equal(t, "DEBU debug msg k=v\n", buf.String())
+}

pkg.go

@@ -45,11 +45,12 @@ func New(w io.Writer) *Logger {
 
 // NewWithOptions returns a new logger using the provided options.
 func NewWithOptions(w io.Writer, o Options) *Logger {
+	lvl := int64(o.Level)
 	l := &Logger{
 		b:               bytes.Buffer{},
 		mu:              &sync.RWMutex{},
 		helpers:         &sync.Map{},
-		level:           int64(o.Level),
+		level:           &lvl,
 		reportTimestamp: o.ReportTimestamp,
 		reportCaller:    o.ReportCaller,
 		prefix:          o.Prefix,
@@ -64,7 +65,7 @@ func NewWithOptions(w io.Writer, o Options) *Logger {
 	l.SetOutput(w)
 	// Detect color profile from the writer and environment.
 	l.SetColorProfile(colorprofile.Detect(w, os.Environ()))
-	l.SetLevel(Level(l.level))
+	l.SetLevel(Level(*l.level))
 	l.SetStyles(DefaultStyles())
 
 	if l.callerFormatter == nil {