logger: add caller info to default implementation (#1575)

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

logger/default.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"runtime"
 	"sort"
 	"sync"
 	"time"
@@ -64,6 +65,10 @@ func (l *defaultLogger) Log(level Level, v ...interface{}) {
 
 	fields["level"] = level.String()
 
+	if _, file, line, ok := runtime.Caller(l.opts.CallerSkipCount); ok {
+		fields["caller"] = fmt.Sprintf("%s:%d", file, line)
+	}
+
 	rec := dlog.Record{
 		Timestamp: time.Now(),
 		Message:   fmt.Sprint(v...),
@@ -101,6 +106,10 @@ func (l *defaultLogger) Logf(level Level, format string, v ...interface{}) {
 
 	fields["level"] = level.String()
 
+	if _, file, line, ok := runtime.Caller(l.opts.CallerSkipCount); ok {
+		fields["caller"] = fmt.Sprintf("%s:%d", file, line)
+	}
+
 	rec := dlog.Record{
 		Timestamp: time.Now(),
 		Message:   fmt.Sprintf(format, v...),
@@ -134,10 +143,11 @@ func (n *defaultLogger) Options() Options {
 func NewLogger(opts ...Option) Logger {
 	// Default options
 	options := Options{
-		Level:   InfoLevel,
+		Level:           InfoLevel,
-		Fields:  make(map[string]interface{}),
+		Fields:          make(map[string]interface{}),
-		Out:     os.Stderr,
+		Out:             os.Stderr,
-		Context: context.Background(),
+		CallerSkipCount: 1,
+		Context:         context.Background(),
 	}
 
 	l := &defaultLogger{opts: options}

logger/logger_test.go

@@ -14,4 +14,5 @@ func TestLogger(t *testing.T) {
 	h2.Trace("trace_msg2")
 	h2.Warn("warn_msg2")
 
+	l.Fields(map[string]interface{}{"key3": "val4"}).Log(InfoLevel, "test_msg")
 }

logger/options.go

@@ -14,6 +14,8 @@ type Options struct {
 	Fields map[string]interface{}
 	// It's common to set this to a file, or leave it default which is `os.Stderr`
 	Out io.Writer
+	// Caller skip frame count for file:line info
+	CallerSkipCount int
 	// Alternative options
 	Context context.Context
 }
@@ -39,6 +41,13 @@ func WithOutput(out io.Writer) Option {
 	}
 }
 
+// WithCallerSkipCount set frame count to skip
+func WithCallerSkipCount(c int) Option {
+	return func(args *Options) {
+		args.CallerSkipCount = c
+	}
+}
+
 func SetOption(k, v interface{}) Option {
 	return func(o *Options) {
 		if o.Context == nil {