remove the stack library dependency (#10)

Signed-off-by: Mark Sagi-Kazar <mark.sagikazar@gmail.com>

go.mod

@@ -2,7 +2,4 @@ module github.com/go-kit/log
 
 go 1.17
 
-require (
-	github.com/go-logfmt/logfmt v0.5.1
-	github.com/go-stack/stack v1.8.1
-)
+require github.com/go-logfmt/logfmt v0.5.1

go.sum

@@ -1,4 +1,2 @@
 github.com/go-logfmt/logfmt v0.5.1 h1:otpy5pqBCBZ1ng9RQ0dPu4PN7ba75Y/aA+UpowDyNVA=
 github.com/go-logfmt/logfmt v0.5.1/go.mod h1:WYhtIu8zTZfxdn5+rREduYbwxfcBr/Vr6KEVveWlfTs=
-github.com/go-stack/stack v1.8.1 h1:ntEHSVwIt7PNXNpgPmVfMrNhLtgjlmnZha2kOpuRiDw=
-github.com/go-stack/stack v1.8.1/go.mod h1:dcoOX6HbPZSZptuspn9bctJ+N/CnF5gGygcUP3XYfe4=

internal/stack/stack.go

@@ -0,0 +1,38 @@
+package stack
+
+import "runtime"
+
+// Caller returns a frame from the stack of the current goroutine. The argument
+// skip is the number of frames to ascend, with 0 identifying the
+// calling function.
+func Caller(skip int) runtime.Frame {
+	var pcs [3]uintptr
+
+	n := runtime.Callers(skip+1, pcs[:])
+	frames := runtime.CallersFrames(pcs[:n])
+	frame, _ := frames.Next()
+	frame, _ = frames.Next()
+
+	return frame
+}
+
+// Trace returns a call stack for the current goroutine with element 0
+// identifying the calling function.
+func Trace() []runtime.Frame {
+	var pcs [512]uintptr
+	n := runtime.Callers(1, pcs[:])
+
+	frames := runtime.CallersFrames(pcs[:n])
+	cs := make([]runtime.Frame, 0, n)
+
+	// Skip extra frame retrieved just to make sure the runtime.sigpanic
+	// special case is handled.
+	frame, more := frames.Next()
+
+	for more {
+		frame, more = frames.Next()
+		cs = append(cs, frame)
+	}
+
+	return cs
+}

log_test.go

@@ -2,12 +2,11 @@ package log_test
 
 import (
 	"bytes"
-	"fmt"
 	"sync"
 	"testing"
 
 	"github.com/go-kit/log"
-	"github.com/go-stack/stack"
+	"github.com/go-kit/log/internal/stack"
 )
 
 func TestContext(t *testing.T) {
@@ -109,7 +108,7 @@ func TestWithPrefixAndSuffix(t *testing.T) {
 // Valuers, regardless of how many times With has been called.
 func TestContextStackDepth(t *testing.T) {
 	t.Parallel()
-	fn := fmt.Sprintf("%n", stack.Caller(0))
+	fn := stack.Caller(0).Function
 
 	var output []interface{}
 
@@ -119,8 +118,8 @@ func TestContextStackDepth(t *testing.T) {
 	}))
 
 	stackValuer := log.Valuer(func() interface{} {
-		for i, c := range stack.Trace() {
-			if fmt.Sprintf("%n", c) == fn {
+		for i, f := range stack.Trace() {
+			if f.Function == fn {
 				return i
 			}
 		}