helper/resource: RetryError for quitting quickly

helper/resource/wait.go

@@ -18,14 +18,29 @@ func Retry(timeout time.Duration, f RetryFunc) error {
  MinTimeout: 500 * time.Millisecond,
  Refresh: func() (interface{}, string, error) {
  err = f()
- if err != nil {
- return 42, "error", nil
+ if err == nil {
+ return 42, "success", nil
  }
 
- return 42, "success", nil
+ if rerr, ok := err.(RetryError); ok {
+ err = rerr.Err
+ return nil, "quit", err
+ }
+
+ return 42, "error", nil
  },
  }
 
  c.WaitForState()
  return err
 }
+
+// RetryError, if returned, will quit the retry immediately with the
+// Err.
+type RetryError struct {
+ Err error
+}
+
+func (e RetryError) Error() string {
+ return e.Err.Error()
+}

helper/resource/wait_test.go

@@ -37,3 +37,26 @@ func TestRetry_timeout(t *testing.T) {
  t.Fatal("should error")
  }
 }
+
+func TestRetry_error(t *testing.T) {
+ t.Parallel()
+
+ expected := fmt.Errorf("nope")
+ f := func() error {
+ return RetryError{expected}
+ }
+
+ errCh := make(chan error)
+ go func() {
+ errCh <- Retry(1*time.Second, f)
+ }()
+
+ select {
+ case err := <-errCh:
+ if err != expected {
+ t.Fatalf("bad: %#v", err)
+ }
+ case <-time.After(5 * time.Second):
+ t.Fatal("timeout")
+ }
+}