feat(log): support generic configurable logger (#3705)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: ReneWerner87

client/client.go

@@ -662,7 +662,7 @@ func NewWithClient(c *fasthttp.Client) *Client {
 		cborMarshal:          cbor.Marshal,
 		cborUnmarshal:        cbor.Unmarshal,
 		xmlUnmarshal:         xml.Unmarshal,
-		logger:               log.DefaultLogger(),
+		logger:               log.DefaultLogger[*log.Logger](),
 	}
 }
 

docs/api/log.md

@@ -25,7 +25,7 @@ const (
 
 ## Custom Log
 
-Fiber provides the `AllLogger` interface for adapting various log libraries.
+Fiber provides the generic `AllLogger[T]` interface for adapting various log libraries.
 
 ```go
 type CommonLogger interface {
@@ -34,9 +34,20 @@ type CommonLogger interface {
     WithLogger
 }
 
-type AllLogger interface {
+type ConfigurableLogger[T any] interface {
+    // SetLevel sets logging level.
+    SetLevel(level Level)
+
+    // SetOutput sets the logger output.
+    SetOutput(w io.Writer)
+
+    // Logger returns the logger instance.
+    Logger() T
+}
+
+type AllLogger[T any] interface {
     CommonLogger
-    ConfigurableLogger
+    ConfigurableLogger[T]
     WithLogger
 }
 ```
@@ -106,7 +117,7 @@ import (
     fiberlog "github.com/gofiber/fiber/v3/log"
 )
 
-var _ fiberlog.AllLogger = (*customLogger)(nil)
+var _ fiberlog.AllLogger[*log.Logger] = (*customLogger)(nil)
 
 type customLogger struct {
     stdlog *log.Logger
@@ -115,9 +126,13 @@ type customLogger struct {
 // Implement required methods for the AllLogger interface...
 
 // Inject your custom logger
-fiberlog.SetLogger(&customLogger{
+fiberlog.SetLogger[*log.Logger](&customLogger{
     stdlog: log.New(os.Stdout, "CUSTOM ", log.LstdFlags),
 })
+
+// Retrieve the underlying *log.Logger for direct use
+std := fiberlog.DefaultLogger[*log.Logger]().Logger()
+std.Println("custom logging")
 ```
 
 ## Set Level
@@ -141,7 +156,7 @@ Setting the log level allows you to control the verbosity of the logs, filtering
 ### Writing Logs to Stderr
 
 ```go
-var logger fiberlog.AllLogger = &defaultLogger{
+var logger fiberlog.AllLogger[*log.Logger] = &defaultLogger{
     stdlog: log.New(os.Stderr, "", log.LstdFlags|log.Lshortfile|log.Lmicroseconds),
     depth:  4,
 }
@@ -193,12 +208,8 @@ You can use Logger to retrieve the logger instance. It is useful when you need t
 To retrieve the Logger instance, use the following method:
 
 ```go
-logger := fiberlog.DefaultLogger() // Call DefaultLogger to get the default logger instance
-
-stdlogger, ok := logger.Logger().(*log.Logger) // Get the logger instance and assert it to *log.Logger
-if !ok {
-    panic("logger is not *log.Logger")
-}
+logger := fiberlog.DefaultLogger[*log.Logger]() // Get the default logger instance
 
+stdlogger := logger.Logger() // stdlogger is *log.Logger
 stdlogger.SetFlags(0) // Hide timestamp by setting flags to 0
 ```

docs/whats_new.md

@@ -995,7 +995,7 @@ INFO Total process count:       1
 
 ## 📃 Log
 
-`fiber.AllLogger` interface now has a new method called `Logger`. This method can be used to get the underlying logger instance from the Fiber logger middleware. This is useful when you want to configure the logger middleware with a custom logger and still want to access the underlying logger instance.
+`fiber.AllLogger[T]` interface now has a new generic type parameter `T` and a method called `Logger`. This method can be used to get the underlying logger instance from the Fiber logger middleware. This is useful when you want to configure the logger middleware with a custom logger and still want to access the underlying logger instance with the appropriate type.
 
 You can find more details about this feature in [/docs/api/log.md](./api/log.md#logger).
 
@@ -1436,6 +1436,7 @@ fiber migrate --to 3.0.0
 - [🧠 Context](#-context-1)
 - [📎 Binding (was Parser)](#-parser)
 - [🔄 Redirect](#-redirect-1)
+- [🧾 Log](#-log-1)
 - [🌎 Client package](#-client-package-1)
 - [🛠️ Utils](#utils-migration)
 - [🧬 Middlewares](#-middlewares-1)
@@ -1903,6 +1904,10 @@ Fiber v3 enhances the redirect functionality by introducing new methods and impr
 
     </details>
 
+#### 🧾 Log
+
+The `ConfigurableLogger` and `AllLogger` interfaces now use generics. You can specify the underlying logger type when implementing these interfaces. While `any` can be used for maximum flexibility in some contexts, when retrieving the concrete logger via `log.DefaultLogger`, you must specify the exact underlying logger type, for example `log.DefaultLogger[*MyLogger]().Logger()`.
+
 ### 🌎 Client package
 
 Fiber v3 introduces a completely rebuilt client package with numerous new features such as Cookiejar, request/response hooks, and more. Here is a guide to help you migrate from Fiber v2 to Fiber v3.

log/default.go

@@ -11,7 +11,7 @@ import (
 	"github.com/valyala/bytebufferpool"
 )
 
-var _ AllLogger = (*defaultLogger)(nil)
+var _ AllLogger[*log.Logger] = (*defaultLogger)(nil)
 
 type defaultLogger struct {
 	stdlog *log.Logger
@@ -211,11 +211,15 @@ func (l *defaultLogger) SetOutput(writer io.Writer) {
 }
 
 // Logger returns the logger instance. It can be used to adjust the logger configurations in case of need.
-func (l *defaultLogger) Logger() any {
+func (l *defaultLogger) Logger() *log.Logger {
 	return l.stdlog
 }
 
 // DefaultLogger returns the default logger.
-func DefaultLogger() AllLogger {
-	return logger
+func DefaultLogger[T any]() AllLogger[T] {
+	if l, ok := logger.(AllLogger[T]); ok {
+		return l
+	}
+
+	return nil
 }

log/default_test.go

@@ -230,9 +230,7 @@ func Test_Logger(t *testing.T) {
 
 	require.Equal(t, underlyingLogger, setLogger.Logger())
 
-	logger, ok := setLogger.Logger().(*log.Logger)
-	require.True(t, ok)
-
+	logger := setLogger.Logger()
 	logger.SetFlags(log.LstdFlags | log.Lshortfile | log.Lmicroseconds)
 	require.Equal(t, log.LstdFlags|log.Lshortfile|log.Lmicroseconds, setLogger.stdlog.Flags())
 }

log/fiberlog.go

@@ -123,8 +123,8 @@ func WithContext(ctx context.Context) CommonLogger {
 
 // SetLogger sets the default logger and the system logger.
 // Note that this method is not concurrent-safe and must not be called
-// after the use of DefaultLogger and global functions privateLog this package.
-func SetLogger(v AllLogger) {
+// after the use of DefaultLogger and global functions from this package.
+func SetLogger[T any](v AllLogger[T]) {
 	logger = v
 }
 

log/fiberlog_test.go

@@ -10,7 +10,7 @@ import (
 
 func Test_DefaultSystemLogger(t *testing.T) {
 	t.Parallel()
-	defaultL := DefaultLogger()
+	defaultL := DefaultLogger[*log.Logger]()
 	require.Equal(t, logger, defaultL)
 }
 
@@ -73,7 +73,7 @@ func Test_Fiberlog_SetLevel(t *testing.T) {
 func Benchmark_DefaultSystemLogger(b *testing.B) {
 	b.ReportAllocs()
 	for b.Loop() {
-		_ = DefaultLogger()
+		_ = DefaultLogger[*log.Logger]()
 	}
 }
 
@@ -141,7 +141,7 @@ func Benchmark_DefaultSystemLogger_Parallel(b *testing.B) {
 	b.ResetTimer()
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
-			_ = DefaultLogger()
+			_ = DefaultLogger[*log.Logger]()
 		}
 	})
 }

log/log.go

@@ -8,7 +8,16 @@ import (
 	"os"
 )
 
-var logger AllLogger = &defaultLogger{
+// baseLogger defines the minimal logger functionality required by the package.
+// It allows storing any logger implementation regardless of its generic type.
+type baseLogger interface {
+	CommonLogger
+	SetLevel(Level)
+	SetOutput(io.Writer)
+	WithContext(ctx context.Context) CommonLogger
+}
+
+var logger baseLogger = &defaultLogger{
 	stdlog: log.New(os.Stderr, "", log.LstdFlags|log.Lshortfile|log.Lmicroseconds),
 	depth:  4,
 }
@@ -53,7 +62,7 @@ type CommonLogger interface {
 }
 
 // ConfigurableLogger provides methods to config a logger.
-type ConfigurableLogger interface {
+type ConfigurableLogger[T any] interface {
 	// SetLevel sets logging level.
 	//
 	// Available levels: Trace, Debug, Info, Warn, Error, Fatal, Panic.
@@ -63,14 +72,14 @@ type ConfigurableLogger interface {
 	SetOutput(w io.Writer)
 
 	// Logger returns the logger instance. It can be used to adjust the logger configurations in case of need.
-	Logger() any
+	Logger() T
 }
 
 // AllLogger is the combination of Logger, FormatLogger, CtxLogger and ConfigurableLogger.
 // Custom extensions can be made through AllLogger
-type AllLogger interface {
+type AllLogger[T any] interface {
 	CommonLogger
-	ConfigurableLogger
+	ConfigurableLogger[T]
 
 	// WithContext returns a new logger with the given context.
 	WithContext(ctx context.Context) CommonLogger

middleware/logger/logger_test.go

@@ -341,10 +341,8 @@ func Test_Logger_LoggerToWriter(t *testing.T) {
 		bytebufferpool.Put(buf)
 	})
 
-	logger := fiberlog.DefaultLogger()
-	stdlogger, ok := logger.Logger().(*log.Logger)
-	require.True(t, ok)
-
+	logger := fiberlog.DefaultLogger[*log.Logger]()
+	stdlogger := logger.Logger()
 	stdlogger.SetFlags(0)
 	logger.SetOutput(buf)
 
@@ -404,7 +402,7 @@ func Test_Logger_LoggerToWriter(t *testing.T) {
 		})
 
 		require.Panics(t, func() {
-			LoggerToWriter(nil, fiberlog.LevelFatal)
+			LoggerToWriter[any](nil, fiberlog.LevelFatal)
 		})
 	}
 }
@@ -1104,7 +1102,7 @@ func Benchmark_Logger(b *testing.B) {
 
 	b.Run("DefaultFormatWithFiberLog", func(bb *testing.B) {
 		app := fiber.New()
-		logger := fiberlog.DefaultLogger()
+		logger := fiberlog.DefaultLogger[*log.Logger]()
 		logger.SetOutput(io.Discard)
 		app.Use(New(Config{
 			Stream: LoggerToWriter(logger, fiberlog.LevelDebug),
@@ -1260,7 +1258,7 @@ func Benchmark_Logger_Parallel(b *testing.B) {
 
 	b.Run("DefaultFormatWithFiberLog", func(bb *testing.B) {
 		app := fiber.New()
-		logger := fiberlog.DefaultLogger()
+		logger := fiberlog.DefaultLogger[*log.Logger]()
 		logger.SetOutput(io.Discard)
 		app.Use(New(Config{
 			Stream: LoggerToWriter(logger, fiberlog.LevelDebug),

middleware/logger/utils.go

@@ -42,12 +42,12 @@ func statusColor(code int, colors fiber.Colors) string {
 	}
 }
 
-type customLoggerWriter struct {
-	loggerInstance fiberlog.AllLogger
+type customLoggerWriter[T any] struct {
+	loggerInstance fiberlog.AllLogger[T]
 	level          fiberlog.Level
 }
 
-func (cl *customLoggerWriter) Write(p []byte) (int, error) {
+func (cl *customLoggerWriter[T]) Write(p []byte) (int, error) {
 	switch cl.level {
 	case fiberlog.LevelTrace:
 		cl.loggerInstance.Trace(utils.UnsafeString(p))
@@ -70,7 +70,7 @@ func (cl *customLoggerWriter) Write(p []byte) (int, error) {
 // You can integrate 3rd party loggers such as zerolog, logrus, etc. to logger middleware using this function.
 //
 // Valid levels: fiberlog.LevelInfo, fiberlog.LevelTrace, fiberlog.LevelWarn, fiberlog.LevelDebug, fiberlog.LevelError
-func LoggerToWriter(logger fiberlog.AllLogger, level fiberlog.Level) io.Writer {
+func LoggerToWriter[T any](logger fiberlog.AllLogger[T], level fiberlog.Level) io.Writer {
 	// Check if customLogger is nil
 	if logger == nil {
 		fiberlog.Panic("LoggerToWriter: customLogger must not be nil")
@@ -81,7 +81,7 @@ func LoggerToWriter(logger fiberlog.AllLogger, level fiberlog.Level) io.Writer {
 		fiberlog.Panic("LoggerToWriter: invalid level")
 	}
 
-	return &customLoggerWriter{
+	return &customLoggerWriter[T]{
 		level:          level,
 		loggerInstance: logger,
 	}