Revert "remove for statement"

This reverts commit 1a4df04.

keeper.go

@@ -3,6 +3,7 @@ package keeper
 import (
 	"context"
 	"errors"
+	"time"
 )
 
 var FailedGetChannel = errors.New("failed to get Channel")
@@ -29,13 +30,17 @@ func ExecWithContext(ctx context.Context, f func() (interface{}, error)) (interf
 // wait channel result until context done
 func waitResult(ctx context.Context, ch chan result) (interface{}, error) {
 	var i result
-	select {
-	case <-ctx.Done():
-		return i.value, ctx.Err()
-	case i, ok := <-ch:
-		if !ok {
-			return nil, FailedGetChannel
+	for {
+		select {
+		case <-ctx.Done():
+			return i.value, ctx.Err()
+		case i, ok := <-ch:
+			if !ok {
+				return nil, FailedGetChannel
+			}
+			return i.value, i.err
+		default:
 		}
-		return i.value, i.err
+		time.Sleep(1 * time.Millisecond)
 	}
 }