update cadvisor to v0.31.0

vendor/github.com/Rican7/retry/retry.go

@@ -0,0 +1,36 @@
+// Package retry provides a simple, stateless, functional mechanism to perform
+// actions repetitively until successful.
+//
+// Copyright © 2016 Trevor N. Suarez (Rican7)
+package retry
+
+import "github.com/Rican7/retry/strategy"
+
+// Action defines a callable function that package retry can handle.
+type Action func(attempt uint) error
+
+// Retry takes an action and performs it, repetitively, until successful.
+//
+// Optionally, strategies may be passed that assess whether or not an attempt
+// should be made.
+func Retry(action Action, strategies ...strategy.Strategy) error {
+	var err error
+
+	for attempt := uint(0); (0 == attempt || nil != err) && shouldAttempt(attempt, strategies...); attempt++ {
+		err = action(attempt)
+	}
+
+	return err
+}
+
+// shouldAttempt evaluates the provided strategies with the given attempt to
+// determine if the Retry loop should make another attempt.
+func shouldAttempt(attempt uint, strategies ...strategy.Strategy) bool {
+	shouldAttempt := true
+
+	for i := 0; shouldAttempt && i < len(strategies); i++ {
+		shouldAttempt = shouldAttempt && strategies[i](attempt)
+	}
+
+	return shouldAttempt
+}