doc: add example about profiler and visualizer

profiler.go

@@ -47,7 +47,7 @@ type span struct {
 }
 
 func (s *span) String() string {
-	return fmt.Sprintf("%s,%s,cost %vns", s.extra.typ, s.extra.name, s.end.Sub(s.begin).Microseconds())
+	return fmt.Sprintf("%s,%s,%vns", s.extra.typ, s.extra.name, s.end.Sub(s.begin).Nanoseconds())
 }
 
 func (t *Profiler) draw(w io.Writer) error {
@@ -61,7 +61,7 @@ func (t *Profiler) draw(w io.Writer) error {
 				path = cur.parent.String() + ";" + path
 				cur = cur.parent
 			}
-			msg := fmt.Sprintf("%s %v\n", path, s.end.Sub(s.begin).Microseconds())
+			msg := fmt.Sprintf("%s %v\n", path, s.end.Sub(s.begin).Nanoseconds())
 
 			if _, err := w.Write([]byte(msg)); err != nil {
 				return fmt.Errorf("write profile -> %w", err)

readme.md

@@ -100,20 +100,22 @@ func main() {
 	}
 }
 ```
-### How to use visualize taskflow
+### How to visualize a taskflow
 ```go
 if err := gotaskflow.Visualizer.Visualize(tf, os.Stdout); err != nil {
 		log.Fatal(err)
 }
 ```
-`Visualize` generate raw string in dot format, just use dot to draw a DAG svg.
-### How to use profile taskflow
+`Visualize` generate raw string in dot format, just use `dot` to draw a DAG svg.
+![example](https://raw.githubusercontent.com/noneback/images/00fb2d98005ff9213a2003e915caf9426725dcbc/graphviz.svg)
+### How to profile a taskflow
 ```go
 if err :=exector.Profile(os.Stdout);err != nil {
 		log.Fatal(err)
 }
 ```
-`Profile` alse generate raw string in flamegraph format, just use flamegraph to draw a flamegraph svg.
+`Profile` alse generate raw string in flamegraph format, just use `flamegraph` to draw a flamegraph svg.
+![example](https://raw.githubusercontent.com/noneback/images/ae31f3ea57f3f1b8d4cf94300a5ff502b2340214/t.svg)
 ## What's next
 - [ ] Taskflow Composition
 - [x] Taskflow Profiler

utils/utils_test.go

@@ -4,61 +4,51 @@ import (
 	"testing"
 )
 
-// UnsafeToString 测试
+
 func TestUnsafeToString(t *testing.T) {
 	original := "Hello, World!"
 	b := []byte(original)
-
-	// 将字节切片转换为字符串
 	s := UnsafeToString(b)
-
 	if s != original {
 		t.Errorf("Expected %q but got %q", original, s)
 	}
 }
 
-// UnsafeToBytes 测试
+
 func TestUnsafeToBytes(t *testing.T) {
 	original := "Hello, World!"
-	// 将字符串转换为字节切片
 	b := UnsafeToBytes(original)
 
 	if string(b) != original {
 		t.Errorf("Expected %q but got %q", original, string(b))
 	}
 }
 
-// RC 结构体测试
 func TestRC(t *testing.T) {
 	rc := &RC{}
 
-	// 测试初始值
 	if rc.Value() != 0 {
 		t.Errorf("Expected count to be 0, got %d", rc.Value())
 	}
 
-	// 测试增加计数
 	rc.Increase()
 	if rc.Value() != 1 {
 		t.Errorf("Expected count to be 1, got %d", rc.Value())
 	}
 
-	// 测试减少计数
 	rc.Decrease()
 	if rc.Value() != 0 {
 		t.Errorf("Expected count to be 0, got %d", rc.Value())
 	}
 
-	// 测试不能减少到负值
 	defer func() {
 		if r := recover(); r == nil {
 			t.Errorf("Expected panic when decreasing below zero, but did not")
 		}
 	}()
-	rc.Decrease() // 这里应该触发 panic
+	rc.Decrease() // should panic
 }
 
-// 测试 Set 和负值
 func TestSet(t *testing.T) {
 	rc := &RC{}
 	rc.Set(5)
@@ -67,7 +57,6 @@ func TestSet(t *testing.T) {
 		t.Errorf("Expected count to be 5, got %d", rc.Value())
 	}
 
-	// 测试负值情况
 	rc.Set(-1)
 
 	if rc.Value() != -1 {