Move to vendor

Signed-off-by: Olivier Gambier <olivier@docker.com>

vendor/github.com/denverdino/aliyungo/util/attempt.go

@@ -0,0 +1,76 @@
+package util
+
+import (
+	"time"
+)
+
+// AttemptStrategy is reused from the goamz package
+
+// AttemptStrategy represents a strategy for waiting for an action
+// to complete successfully. This is an internal type used by the
+// implementation of other packages.
+type AttemptStrategy struct {
+	Total time.Duration // total duration of attempt.
+	Delay time.Duration // interval between each try in the burst.
+	Min   int           // minimum number of retries; overrides Total
+}
+
+type Attempt struct {
+	strategy AttemptStrategy
+	last     time.Time
+	end      time.Time
+	force    bool
+	count    int
+}
+
+// Start begins a new sequence of attempts for the given strategy.
+func (s AttemptStrategy) Start() *Attempt {
+	now := time.Now()
+	return &Attempt{
+		strategy: s,
+		last:     now,
+		end:      now.Add(s.Total),
+		force:    true,
+	}
+}
+
+// Next waits until it is time to perform the next attempt or returns
+// false if it is time to stop trying.
+func (a *Attempt) Next() bool {
+	now := time.Now()
+	sleep := a.nextSleep(now)
+	if !a.force && !now.Add(sleep).Before(a.end) && a.strategy.Min <= a.count {
+		return false
+	}
+	a.force = false
+	if sleep > 0 && a.count > 0 {
+		time.Sleep(sleep)
+		now = time.Now()
+	}
+	a.count++
+	a.last = now
+	return true
+}
+
+func (a *Attempt) nextSleep(now time.Time) time.Duration {
+	sleep := a.strategy.Delay - now.Sub(a.last)
+	if sleep < 0 {
+		return 0
+	}
+	return sleep
+}
+
+// HasNext returns whether another attempt will be made if the current
+// one fails. If it returns true, the following call to Next is
+// guaranteed to return true.
+func (a *Attempt) HasNext() bool {
+	if a.force || a.strategy.Min > a.count {
+		return true
+	}
+	now := time.Now()
+	if now.Add(a.nextSleep(now)).Before(a.end) {
+		a.force = true
+		return true
+	}
+	return false
+}