perf(recover): replace bytes with strings in function for better performance (#4252)

Co-authored-by: huangzw <huangzw@2345.com>

recovery.go

@@ -19,12 +19,9 @@ import (
 	"time"
 )
 
-var (
-	dunno     = []byte("???")
-	centerDot = []byte("·")
-	dot       = []byte(".")
-	slash     = []byte("/")
-)
+const dunno = "???"
+
+var dunnoBytes = []byte(dunno)
 
 // RecoveryFunc defines the function passable to CustomRecovery.
 type RecoveryFunc func(c *Context, err any)
@@ -138,18 +135,18 @@ func stack(skip int) []byte {
 func source(lines [][]byte, n int) []byte {
 	n-- // in stack trace, lines are 1-indexed but our array is 0-indexed
 	if n < 0 || n >= len(lines) {
-		return dunno
+		return dunnoBytes
 	}
 	return bytes.TrimSpace(lines[n])
 }
 
 // function returns, if possible, the name of the function containing the PC.
-func function(pc uintptr) []byte {
+func function(pc uintptr) string {
 	fn := runtime.FuncForPC(pc)
 	if fn == nil {
 		return dunno
 	}
-	name := []byte(fn.Name())
+	name := fn.Name()
 	// The name includes the path name to the package, which is unnecessary
 	// since the file name is already included.  Plus, it has center dots.
 	// That is, we see
@@ -158,13 +155,13 @@ func function(pc uintptr) []byte {
 	//	*T.ptrmethod
 	// Also the package path might contain dot (e.g. code.google.com/...),
 	// so first eliminate the path prefix
-	if lastSlash := bytes.LastIndex(name, slash); lastSlash >= 0 {
+	if lastSlash := strings.LastIndexByte(name, '/'); lastSlash >= 0 {
 		name = name[lastSlash+1:]
 	}
-	if period := bytes.Index(name, dot); period >= 0 {
+	if period := strings.IndexByte(name, '.'); period >= 0 {
 		name = name[period+1:]
 	}
-	name = bytes.ReplaceAll(name, centerDot, dot)
+	name = strings.ReplaceAll(name, "·", ".")
 	return name
 }
 

recovery_test.go

@@ -90,14 +90,14 @@ func TestPanicWithAbort(t *testing.T) {
 
 func TestSource(t *testing.T) {
 	bs := source(nil, 0)
-	assert.Equal(t, dunno, bs)
+	assert.Equal(t, dunnoBytes, bs)
 
 	in := [][]byte{
 		[]byte("Hello world."),
 		[]byte("Hi, gin.."),
 	}
 	bs = source(in, 10)
-	assert.Equal(t, dunno, bs)
+	assert.Equal(t, dunnoBytes, bs)
 
 	bs = source(in, 1)
 	assert.Equal(t, []byte("Hello world."), bs)