client-go/rest: backoff with context support

The BackoffManager interface sleeps without considering the caller's context,
i.e. cancellation is not supported. This alone is reason enough to deprecate it
and to replace it with an interface that supports a context parameter.

The other reason is that contextual logging needs that parameter.

Kubernetes-commit: b15a1943d51adfb8c5e0185d58d25e038c3d6ade

rest/with_retry.go

@@ -209,18 +209,18 @@ func (r *withRetry) Before(ctx context.Context, request *Request) error {
 		// we do a backoff sleep before the first attempt is made,
 		// (preserving current behavior).
 		if request.backoff != nil {
-			request.backoff.Sleep(request.backoff.CalculateBackoff(url))
+			request.backoff.SleepWithContext(ctx, request.backoff.CalculateBackoffWithContext(ctx, url))
 		}
 		return nil
 	}
 
 	// if we are here, we have made attempt(s) at least once before.
 	if request.backoff != nil {
-		delay := request.backoff.CalculateBackoff(url)
+		delay := request.backoff.CalculateBackoffWithContext(ctx, url)
 		if r.retryAfter.Wait > delay {
 			delay = r.retryAfter.Wait
 		}
-		request.backoff.Sleep(delay)
+		request.backoff.SleepWithContext(ctx, delay)
 	}
 
 	// We are retrying the request that we already send to
@@ -258,9 +258,9 @@ func (r *withRetry) After(ctx context.Context, request *Request, resp *http.Resp
 
 	if request.c.base != nil {
 		if err != nil {
-			request.backoff.UpdateBackoff(request.URL(), err, 0)
+			request.backoff.UpdateBackoffWithContext(ctx, request.URL(), err, 0)
 		} else {
-			request.backoff.UpdateBackoff(request.URL(), err, resp.StatusCode)
+			request.backoff.UpdateBackoffWithContext(ctx, request.URL(), err, resp.StatusCode)
 		}
 	}
 }