diff --git a/util/retry/util.go b/util/retry/util.go index c80ff087..15e2722f 100644 --- a/util/retry/util.go +++ b/util/retry/util.go @@ -42,43 +42,64 @@ var DefaultBackoff = wait.Backoff{ Jitter: 0.1, } -// OnError executes the provided function repeatedly, retrying if the server returns a specified -// error. Callers should preserve previous executions if they wish to retry changes. It performs an -// exponential backoff. -// -// var pod *api.Pod -// err := retry.OnError(DefaultBackoff, errors.IsConflict, func() (err error) { -// pod, err = c.Pods("mynamespace").UpdateStatus(podStatus) -// return -// }) -// if err != nil { -// // may be conflict if max retries were hit -// return err -// } -// ... -// -// TODO: Make Backoff an interface? -func OnError(backoff wait.Backoff, errorFunc func(error) bool, fn func() error) error { - var lastConflictErr error +// OnError allows the caller to retry fn in case the error returned by fn is retriable +// according to the provided function. backoff defines the maximum retries and the wait +// interval between two retries. +func OnError(backoff wait.Backoff, retriable func(error) bool, fn func() error) error { + var lastErr error err := wait.ExponentialBackoff(backoff, func() (bool, error) { err := fn() switch { case err == nil: return true, nil - case errorFunc(err): - lastConflictErr = err + case retriable(err): + lastErr = err return false, nil default: return false, err } }) if err == wait.ErrWaitTimeout { - err = lastConflictErr + err = lastErr } return err } -// RetryOnConflict executes the function function repeatedly, retrying if the server returns a conflicting +// RetryOnConflict is used to make an update to a resource when you have to worry about +// conflicts caused by other code making unrelated updates to the resource at the same +// time. fn should fetch the resource to be modified, make appropriate changes to it, try +// to update it, and return (unmodified) the error from the update function. On a +// successful update, RetryOnConflict will return nil. If the update function returns a +// "Conflict" error, RetryOnConflict will wait some amount of time as described by +// backoff, and then try again. On a non-"Conflict" error, or if it retries too many times +// and gives up, RetryOnConflict will return an error to the caller. +// +// err := retry.RetryOnConflict(retry.DefaultRetry, func() error { +// // Fetch the resource here; you need to refetch it on every try, since +// // if you got a conflict on the last update attempt then you need to get +// // the current version before making your own changes. +// pod, err := c.Pods("mynamespace").Get(name, metav1.GetOptions{}) +// if err ! nil { +// return err +// } +// +// // Make whatever updates to the resource are needed +// pod.Status.Phase = v1.PodFailed +// +// // Try to update +// _, err = c.Pods("mynamespace").UpdateStatus(pod) +// // You have to return err itself here (not wrapped inside another error) +// // so that RetryOnConflict can identify it correctly. +// return err +// }) +// if err != nil { +// // May be conflict if max retries were hit, or may be something unrelated +// // like permissions or a network error +// return err +// } +// ... +// +// TODO: Make Backoff an interface? func RetryOnConflict(backoff wait.Backoff, fn func() error) error { return OnError(backoff, errors.IsConflict, fn) }