feat(misc/timer): time cost func

misc/timer/timer.go

@@ -0,0 +1,10 @@
+package timer
+
+import "time"
+
+func Span() func() time.Duration {
+	t := time.Now()
+	return func() time.Duration {
+		return time.Since(t)
+	}
+}

misc/timer/timer_test.go

@@ -0,0 +1,14 @@
+package timer_test
+
+import (
+	"testing"
+	"time"
+
+	"github.com/xoctopus/x/misc/timer"
+)
+
+func TestSpan(t *testing.T) {
+	cost := timer.Span()
+	time.Sleep(time.Second)
+	t.Log(cost())
+}