Golang 库: golang slog 怎么设置日志 Debug 等级

func main() {
 slog.Debug("debug")
 slog.Info("info")
 slog.Warn("warn")
 slog.Error("err", fmt.Errorf("game over"))
 // slog.Fatal("don't support")
}

// 2023/01/06 07:41:50 INFO info
// 2023/01/06 07:41:50 WARN warn
// 2023/01/06 07:41:50 ERROR err err="game over"

func main() {
 slog.Debug("debug")
}

// Debug calls Logger.Debug on the default logger.
func Debug(msg string, args ...any) {
 Default().LogDepth(1, LevelDebug, msg, args...)
}

func (l *Logger) LogDepth(calldepth int, level Level, msg string, args ...any) {
 if !l.Enabled(level) {
  return
 }
 var pcs [1]uintptr
 runtime.Callers(calldepth+2, pcs[:])
 l.logPC(nil, pcs[0], level, msg, args...)
}

var defaultLogger atomic.Value

func init() {
 defaultLogger.Store(New(newDefaultHandler(log.Output)))
}

// Default returns the default Logger.
func Default() *Logger { return defaultLogger.Load().(*Logger) }

func newDefaultHandler(output func(int, string) error) *defaultHandler {
 return &defaultHandler{
  ch:     &commonHandler{json: false},
  output: output,
 }
}

func (*defaultHandler) Enabled(l Level) bool {
 return l >= LevelInfo
}

// To create a new Logger, call [New] or a Logger method
// that begins "With".
type Logger struct {
 handler Handler // for structured logging
 ctx     context.Context
}

// New creates a new Logger with the given non-nil Handler and a nil context.
func New(h Handler) *Logger {
 if h == nil {
  panic("nil Handler")
 }
 return &Logger{handler: h}
}

// Any of the Handler's methods may be called concurrently with itself
// or with other methods. It is the responsibility of the Handler to
// manage this concurrency.
type Handler interface {
 // Enabled reports whether the handler handles records at the given level.
 // The handler ignores records whose level is lower.
 // Enabled is called early, before any arguments are processed,
 // to save effort if the log event should be discarded.
 Enabled(Level) bool
 Handle(r Record) error
 WithAttrs(attrs []Attr) Handler
 WithGroup(name string) Handler
}

// 定义了自己的 debugHanlder
type debugHandler struct {
 slog.Handler
}

// newDebugLogger 使用 slog Default Handler 作为实际载体
func newDebugLogger() *slog.Logger {
 dh := &debugHandler{
  // handler 使用 slog 默认的 Handler
  slog.Default().Handler(),
 }

 return slog.New(dh)
}

// Enabled 重写了默认的日志登记的判断方法，支持 Debug 日志
func (dh *debugHandler) Enabled(l slog.Level) bool {
 return l >= slog.LevelDebug
}

func main() {

 // 创建 debugLogger 对象
 log := newDebugLogger()

 log.Debug("debug")
 log.Info("info")
 log.Warn("warn")
 log.Error("err", fmt.Errorf("game over"))
 // log.Fatal("don't support")
}

// 2023/01/06 09:15:18 DEBUG debug
// 2023/01/06 09:15:18 INFO info
// 2023/01/06 09:15:18 WARN warn
// 2023/01/06 09:15:18 ERROR err err="game over"

package main

import (
 "os"

 "golang.org/x/exp/slog"
)

// A LevelHandler wraps a Handler with an Enabled method
// that returns false for levels below a minimum.
type LevelHandler struct {
 level   slog.Leveler
 handler slog.Handler
}

// NewLevelHandler returns a LevelHandler with the given level.
// All methods except Enabled delegate to h.
func NewLevelHandler(level slog.Leveler, h slog.Handler) *LevelHandler {
 // Optimization: avoid chains of LevelHandlers.
 if lh, ok := h.(*LevelHandler); ok {
  h = lh.Handler()
 }
 return &LevelHandler{level, h}
}

// Enabled implements Handler.Enabled by reporting whether
// level is at least as large as h's level.
func (h *LevelHandler) Enabled(level slog.Level) bool {
 return level >= h.level.Level()
}

// Handle implements Handler.Handle.
func (h *LevelHandler) Handle(r slog.Record) error {
 return h.handler.Handle(r)
}

// WithAttrs implements Handler.WithAttrs.
func (h *LevelHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
 return NewLevelHandler(h.level, h.handler.WithAttrs(attrs))
}

// WithGroup implements Handler.WithGroup.
func (h *LevelHandler) WithGroup(name string) slog.Handler {
 return NewLevelHandler(h.level, h.handler.WithGroup(name))
}

// Handler returns the Handler wrapped by h.
func (h *LevelHandler) Handler() slog.Handler {
 return h.handler
}

func main() {
 th := slog.HandlerOptions{
  // Remove time from the output.
  ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
   if a.Key == slog.TimeKey {
    return slog.Attr{}
   }
   return a
  },
 }.NewTextHandler(os.Stdout)

 logger := slog.New(NewLevelHandler(slog.LevelWarn, th))
 logger.Info("not printed")
 logger.Warn("printed")

}

// level=WARN msg=printed

func TestDefault(t *testing.T) {

 log := Default().SetLevel(DebugLevel)
 err := errors.New("New_ERROR")

 log = log.With(
  "kk", "vv",
  "caller", CallerFile(4, false),
  "gg",
 )

 log.Debug("number=%d", 1)
 log.Info("number=%d", 1)
 log.Warn(err)
 log.Error(err)

 ctx := WithLogger(context.Background(), log)
 subcaller(ctx)
}


func subcaller(ctx context.Context) {
 log := FromContext(ctx)

 log = log.Start() // time cost
 defer log.Stop()

 time.Sleep(532 * time.Millisecond)
 log.Info("account=%d", 100)
}

// 2023/01/06 10:31:53 DEBUG number=1 kk=vv caller=logr_test.go:21#TestDefault gg=LACK_Unknown
// 2023/01/06 10:31:53 INFO number=1 kk=vv caller=logr_test.go:22#TestDefault gg=LACK_Unknown
// 2023/01/06 10:31:53 WARN New_ERROR kk=vv caller=logr_test.go:23#TestDefault gg=LACK_Unknown
// 2023/01/06 10:31:53 ERROR New_ERROR kk=vv caller=logr_test.go:24#TestDefault gg=LACK_Unknown
// 2023/01/06 10:31:53 INFO account=100 kk=vv caller=logr_test.go:37#subcaller gg=LACK_Unknown
// 2023/01/06 10:31:53 INFO time-cost kk=vv caller=logr.go:101#Stop gg=LACK_Unknown cost=533ms cost_caller=logr_test.go:38#subcaller