feat(logger): implement slog.Handler

This implements slog.Handler interface. You can use Log as an slog
handler.

context_test.go

@@ -3,7 +3,7 @@ package log
 import (
  "bytes"
  "context"
- "io/ioutil"
+ "io"
  "testing"
 
  "github.com/stretchr/testify/require"
@@ -14,7 +14,7 @@ func TestLogContext_empty(t *testing.T) {
 }
 
 func TestLogContext_simple(t *testing.T) {
- l := New(ioutil.Discard)
+ l := New(io.Discard)
  ctx := WithContext(context.Background(), l)
  require.Equal(t, l, FromContext(ctx))
 }

go.mod

@@ -7,6 +7,7 @@ require (
  github.com/go-logfmt/logfmt v0.6.0
  github.com/muesli/termenv v0.15.2
  github.com/stretchr/testify v1.8.4
+ golang.org/x/exp v0.0.0-20231006140011-7918f672742d
 )
 
 require (
@@ -18,6 +19,6 @@ require (
  github.com/muesli/reflow v0.3.0 // indirect
  github.com/pmezard/go-difflib v1.0.0 // indirect
  github.com/rivo/uniseg v0.2.0 // indirect
- golang.org/x/sys v0.12.0 // indirect
+ golang.org/x/sys v0.13.0 // indirect
  gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -7,6 +7,7 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/go-logfmt/logfmt v0.6.0 h1:wGYYu3uicYdqXVgoYbvnkrPVXkuLM1p1ifugDMEdRi4=
 github.com/go-logfmt/logfmt v0.6.0/go.mod h1:WYhtIu8zTZfxdn5+rREduYbwxfcBr/Vr6KEVveWlfTs=
+github.com/google/go-cmp v0.5.8/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/lucasb-eyer/go-colorful v1.2.0 h1:1nnpGOrhyZZuNyfu1QjKiUICQ74+3FNCN69Aj6K7nkY=
 github.com/lucasb-eyer/go-colorful v1.2.0/go.mod h1:R4dSotOR9KMtayYi1e77YzuveK+i7ruzyGqttikkLy0=
 github.com/mattn/go-isatty v0.0.18 h1:DOKFKCQ7FNG2L1rbrmstDN4QVRdS89Nkh85u68Uwp98=
@@ -31,10 +32,60 @@ github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/crypto v0.13.0/go.mod h1:y6Z2r+Rw4iayiXXAIxJIDAJ1zMW4yaTpebo8fPOliYc=
+golang.org/x/crypto v0.14.0/go.mod h1:MVFd36DqK4CsrnJYDkBA3VC4m2GkXAM0PvzMCn4JQf4=
+golang.org/x/exp v0.0.0-20231006140011-7918f672742d h1:jtJma62tbqLibJ5sFQz8bKtEM8rJBtfilJ2qTU199MI=
+golang.org/x/exp v0.0.0-20231006140011-7918f672742d/go.mod h1:ldy0pHrwJyGW56pPQzzkH36rKxoZW1tw7ZJpeKx+hdo=
+golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
+golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
+golang.org/x/mod v0.12.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
+golang.org/x/mod v0.13.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
+golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
+golang.org/x/net v0.6.0/go.mod h1:2Tu9+aMcznHK/AK1HMvgo6xiTLG5rD5rZLDS+rp2Bjs=
+golang.org/x/net v0.10.0/go.mod h1:0qNGK6F8kojg2nk9dLZ2mShWaEBan6FAoqfSigmmuDg=
+golang.org/x/net v0.15.0/go.mod h1:idbUs1IY1+zTqbi8yxTbhexhEEk5ur9LInksu6HrEpk=
+golang.org/x/net v0.16.0/go.mod h1:NxSsAGuq816PNPmqtQdLE42eU2Fs7NoRIZrHJAlaCOE=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.3.0/go.mod h1:FU7BRWz2tNW+3quACPkgCx/L+uEAv1htQ0V83Z9Rj+Y=
+golang.org/x/sync v0.4.0/go.mod h1:FU7BRWz2tNW+3quACPkgCx/L+uEAv1htQ0V83Z9Rj+Y=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.7.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.12.0 h1:CM0HF96J0hcLAwsHPJZjfdNzs0gftsLfgKt57wWHJ0o=
+golang.org/x/sys v0.8.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.12.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.13.0 h1:Af8nKPmuFypiUBjVoU9V20FiaFXOcuZI21p0ycVYYGE=
+golang.org/x/sys v0.13.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
+golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k=
+golang.org/x/term v0.8.0/go.mod h1:xPskH00ivmX89bAKVGSKKtLOWNx2+17Eiy94tnKShWo=
+golang.org/x/term v0.12.0/go.mod h1:owVbMEjm3cBLCHdkQu9b1opXd4ETQWc3BhuQGKgXgvU=
+golang.org/x/term v0.13.0/go.mod h1:LTmsnFJwVN6bCy1rVCoS+qHT1HhALEFxKncY3WNNh4U=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
+golang.org/x/text v0.9.0/go.mod h1:e1OnstbJyHTd6l/uOt8jFFHp6TRDWZR/bV3emEE/zU8=
+golang.org/x/text v0.13.0/go.mod h1:TvPlkZtksWOMsz7fbANvkp4WM8x/WCo/om8BMLbz+aE=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
+golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU=
+golang.org/x/tools v0.13.0/go.mod h1:HvlwmtVNQAhOuCjW7xxvovg8wbNq7LwfXh/k7wXUl58=
+golang.org/x/tools v0.14.0/go.mod h1:uYBEerGOWcJyEORxN+Ek8+TT266gXkNlHdJBwexUsBg=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

json_test.go

@@ -177,5 +177,5 @@ func TestJsonCustomKey(t *testing.T) {
  logger.SetFormatter(JSONFormatter)
  logger.SetReportTimestamp(true)
  logger.Info("info")
- require.Equal(t, "{\"lvl\":\"info\",\"msg\":\"info\",\"time\":\"0001/01/01 00:00:00\"}\n", buf.String())
+ require.Equal(t, "{\"lvl\":\"info\",\"msg\":\"info\",\"time\":\"0002/01/01 00:00:00\"}\n", buf.String())
 }

level.go

@@ -1,6 +1,10 @@
 package log
 
-import "strings"
+import (
+ "strings"
+
+ "golang.org/x/exp/slog"
+)
 
 // Level is a logging level.
 type Level int32
@@ -55,3 +59,21 @@ func ParseLevel(level string) Level {
  return InfoLevel
  }
 }
+
+// fromSlogLevel converts slog.Level to log.Level.
+var fromSlogLevel = map[slog.Level]Level{
+ slog.LevelDebug: DebugLevel,
+ slog.LevelInfo: InfoLevel,
+ slog.LevelWarn: WarnLevel,
+ slog.LevelError: ErrorLevel,
+ slog.Level(12): FatalLevel,
+}
+
+// toSlogLevel converts log.Level to slog.Level.
+var toSlogLevel = map[Level]slog.Level{
+ DebugLevel: slog.LevelDebug,
+ InfoLevel: slog.LevelInfo,
+ WarnLevel: slog.LevelWarn,
+ ErrorLevel: slog.LevelError,
+ FatalLevel: slog.Level(12),
+}

logger.go

@@ -2,17 +2,19 @@ package log
 
 import (
  "bytes"
+ "context"
  "fmt"
  "io"
- "io/ioutil"
  "os"
  "runtime"
  "strings"
  "sync"
  "sync/atomic"
+ "time"
 
  "github.com/charmbracelet/lipgloss"
  "github.com/muesli/termenv"
+ "golang.org/x/exp/slog"
 )
 
 var (
@@ -48,6 +50,53 @@ type Logger struct {
  helpers *sync.Map
 }
 
+// Enabled reports whether the logger is enabled for the given level.
+//
+// Implements slog.Handler.
+func (l *Logger) Enabled(_ context.Context, level slog.Level) bool {
+ return atomic.LoadInt32(&l.level) <= int32(fromSlogLevel[level])
+}
+
+// Handle handles the Record. It will only be called if Enabled returns true.
+//
+// Implements slog.Handler.
+func (l *Logger) Handle(_ context.Context, record slog.Record) error {
+ fields := make([]interface{}, 0, record.NumAttrs()*2)
+ record.Attrs(func(a slog.Attr) bool {
+ fields = append(fields, a.Key, a.Value.String())
+ return true
+ })
+ // Get the caller frame using the record's PC.
+ frames := runtime.CallersFrames([]uintptr{record.PC})
+ frame, _ := frames.Next()
+ l.handle(fromSlogLevel[record.Level], record.Time, []runtime.Frame{frame}, record.Message, fields...)
+ return nil
+}
+
+// WithAttrs returns a new Handler with the given attributes added.
+//
+// Implements slog.Handler.
+func (l *Logger) WithAttrs(attrs []slog.Attr) slog.Handler {
+ fields := make([]interface{}, 0, len(attrs)*2)
+ for _, attr := range attrs {
+ fields = append(fields, attr.Key, attr.Value)
+ }
+ return l.With(fields...)
+}
+
+// WithGroup returns a new Handler with the given group name prepended to the
+// current group name or prefix.
+//
+// Implements slog.Handler.
+func (l *Logger) WithGroup(name string) slog.Handler {
+ if l.prefix != "" {
+ name = l.prefix + "." + name
+ }
+ return l.WithPrefix(name)
+}
+
+var _ slog.Handler = (*Logger)(nil)
+
 func (l *Logger) log(level Level, msg interface{}, keyvals ...interface{}) {
  if atomic.LoadUint32(&l.isDiscard) != 0 {
  return
@@ -58,20 +107,40 @@ func (l *Logger) log(level Level, msg interface{}, keyvals ...interface{}) {
  return
  }
 
+ var frame runtime.Frame
+ if l.reportCaller {
+ // Skip log.log, the caller, and any offset added.
+ frames := l.frames(l.callerOffset + 2)
+ for {
+ f, more := frames.Next()
+ _, helper := l.helpers.Load(f.Function)
+ if !helper || !more {
+ // Found a frame that wasn't a helper function.
+ // Or we ran out of frames to check.
+ frame = f
+ break
+ }
+ }
+ }
+ l.handle(level, l.timeFunc(), []runtime.Frame{frame}, msg, keyvals...)
+}
+
+func (l *Logger) handle(level Level, ts time.Time, frames []runtime.Frame, msg interface{}, keyvals ...interface{}) {
  var kvs []interface{}
- if l.reportTimestamp {
- kvs = append(kvs, TimestampKey, l.timeFunc())
+ if l.reportTimestamp && !ts.IsZero() {
+ kvs = append(kvs, TimestampKey, ts)
  }
 
  if level != noLevel {
  kvs = append(kvs, LevelKey, level)
  }
 
- if l.reportCaller {
- // Call stack is log.Error -> log.log (2)
- file, line, fn := l.fillLoc(l.callerOffset + 2)
- caller := l.callerFormatter(file, line, fn)
- kvs = append(kvs, CallerKey, caller)
+ if l.reportCaller && len(frames) > 0 && frames[0].PC != 0 {
+ file, line, fn := l.location(frames)
+ if file != "" {
+ caller := l.callerFormatter(file, line, fn)
+ kvs = append(kvs, CallerKey, caller)
+ }
  }
 
  if l.prefix != "" {
@@ -117,34 +186,32 @@ func (l *Logger) Helper() {
 }
 
 func (l *Logger) helper(skip int) {
- _, _, fn := location(skip + 1)
- l.helpers.LoadOrStore(fn, struct{}{})
+ var pcs [1]uintptr
+ // Skip runtime.Callers, and l.helper
+ n := runtime.Callers(skip+2, pcs[:])
+ frames := runtime.CallersFrames(pcs[:n])
+ frame, _ := frames.Next()
+ l.helpers.LoadOrStore(frame.Function, struct{}{})
 }
 
-func (l *Logger) fillLoc(skip int) (file string, line int, fn string) {
+// frames returns the runtime.Frames for the caller.
+func (l *Logger) frames(skip int) *runtime.Frames {
  // Copied from testing.T
  const maxStackLen = 50
  var pc [maxStackLen]uintptr
 
- // Skip two extra frames to account for this function
- // and runtime.Callers itself.
+ // Skip runtime.Callers, and l.frame
  n := runtime.Callers(skip+2, pc[:])
  frames := runtime.CallersFrames(pc[:n])
- for {
- frame, more := frames.Next()
- _, helper := l.helpers.Load(frame.Function)
- if !helper || !more {
- // Found a frame that wasn't a helper function.
- // Or we ran out of frames to check.
- return frame.File, frame.Line, frame.Function
- }
- }
+ return frames
 }
 
-func location(skip int) (file string, line int, fn string) {
- pc, file, line, _ := runtime.Caller(skip + 1)
- f := runtime.FuncForPC(pc)
- return file, line, f.Name()
+func (l *Logger) location(frames []runtime.Frame) (file string, line int, fn string) {
+ if len(frames) == 0 {
+ return "", 0, ""
+ }
+ f := frames[0]
+ return f.File, f.Line, f.Function
 }
 
 // Cleanup a path by returning the last n segments of the path only.
@@ -248,7 +315,7 @@ func (l *Logger) SetOutput(w io.Writer) {
  }
  l.w = w
  var isDiscard uint32
- if w == ioutil.Discard {
+ if w == io.Discard {
  isDiscard = 1
  }
  atomic.StoreUint32(&l.isDiscard, isDiscard)

options_test.go

@@ -3,7 +3,7 @@ package log
 import (
  "bytes"
  "fmt"
- "io/ioutil"
+ "io"
  "testing"
 
  "github.com/stretchr/testify/require"
@@ -15,7 +15,7 @@ func TestOptions(t *testing.T) {
  ReportCaller: true,
  Fields: []interface{}{"foo", "bar"},
  }
- logger := NewWithOptions(ioutil.Discard, opts)
+ logger := NewWithOptions(io.Discard, opts)
  require.Equal(t, ErrorLevel, logger.GetLevel())
  require.True(t, logger.reportCaller)
  require.False(t, logger.reportTimestamp)
@@ -28,7 +28,9 @@ func TestOptions(t *testing.T) {
 func TestCallerFormatter(t *testing.T) {
  var buf bytes.Buffer
  l := NewWithOptions(&buf, Options{ReportCaller: true})
- file, line, fn := l.fillLoc(0)
+ frames := l.frames(0)
+ frame, _ := frames.Next()
+ file, line, fn := frame.File, frame.Line, frame.Function
  hi := func() { l.Info("hi") }
  cases := []struct {
  name string
@@ -37,12 +39,12 @@ func TestCallerFormatter(t *testing.T) {
  }{
  {
  name: "short caller formatter",
- expected: fmt.Sprintf("INFO <log/options_test.go:%d> hi\n", line+1),
+ expected: fmt.Sprintf("INFO <log/options_test.go:%d> hi\n", line+3),
  format: ShortCallerFormatter,
  },
  {
  name: "long caller formatter",
- expected: fmt.Sprintf("INFO <%s:%d> hi\n", file, line+1),
+ expected: fmt.Sprintf("INFO <%s:%d> hi\n", file, line+3),
  format: LongCallerFormatter,
  },
  {
@@ -54,7 +56,7 @@ func TestCallerFormatter(t *testing.T) {
  },
  {
  name: "custom caller formatter",
- expected: fmt.Sprintf("INFO <%s:%d:%s.func1> hi\n", file, line+1, fn),
+ expected: fmt.Sprintf("INFO <%s:%d:%s.func1> hi\n", file, line+3, fn),
  format: func(file string, line int, fn string) string {
  return fmt.Sprintf("%s:%d:%s", file, line, fn)
  },

pkg.go

@@ -151,7 +151,6 @@ func WithPrefix(prefix string) *Logger {
 // and skips it for source location information.
 // It's the equivalent of testing.TB.Helper().
 func Helper() {
- // skip this function frame
  defaultLogger.helper(1)
 }