blob: 327864f48c45946afd6088f3f27a27d636bd3da4 [file] [log] [blame]
// Copyright 2015 The Vanadium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package testutil
// TODO(sadovsky): RetryFor is not really testing-specific; maybe move it
// elsewhere.
import (
// TryAgain should be returned by the function provided to RetryFor to indicate
// that the function should be retried. If the function returns a non-TryAgain
// error, RetryFor will exit.
func TryAgain(err error) error {
return tryAgain{error: err}
type tryAgain struct{ error }
// TimeoutError is returned by RetryFor when the specified timeout is reached.
type TimeoutError struct {
// Timeout is the user-specified timeout.
Timeout time.Duration
// LastErr is the most recent TryAgain error returned by the user-provided
// function.
LastErr error
func (e *TimeoutError) Error() string {
return fmt.Sprintf("timed out after %v: %v", e.Timeout, e.LastErr)
// RetryFor calls fn repeatedly, with a brief delay after each invocation, until
// either (1) fn returns something other than TryAgain or (2) the specified
// timeout is reached. RetryFor returns nil, TimeoutError, or the non-TryAgain
// error returned by fn.
func RetryFor(timeout time.Duration, fn func() error) error {
deadline := time.Now().Add(timeout)
for {
err := fn()
tryAgainErr, ok := err.(tryAgain)
if !ok {
return err
if time.Now().After(deadline) {
return &TimeoutError{Timeout: timeout, LastErr: tryAgainErr.error}
time.Sleep(100 * time.Millisecond)