[VOL-3210] Added Retry feature in BBSim for EAPOL and DHCP
Change-Id: If0586c804f906998ebc09b7770fd6a749a3a2762
diff --git a/vendor/github.com/jpillora/backoff/backoff.go b/vendor/github.com/jpillora/backoff/backoff.go
new file mode 100644
index 0000000..d113e68
--- /dev/null
+++ b/vendor/github.com/jpillora/backoff/backoff.go
@@ -0,0 +1,100 @@
+// Package backoff provides an exponential-backoff implementation.
+package backoff
+
+import (
+ "math"
+ "math/rand"
+ "sync/atomic"
+ "time"
+)
+
+// Backoff is a time.Duration counter, starting at Min. After every call to
+// the Duration method the current timing is multiplied by Factor, but it
+// never exceeds Max.
+//
+// Backoff is not generally concurrent-safe, but the ForAttempt method can
+// be used concurrently.
+type Backoff struct {
+ attempt uint64
+ // Factor is the multiplying factor for each increment step
+ Factor float64
+ // Jitter eases contention by randomizing backoff steps
+ Jitter bool
+ // Min and Max are the minimum and maximum values of the counter
+ Min, Max time.Duration
+}
+
+// Duration returns the duration for the current attempt before incrementing
+// the attempt counter. See ForAttempt.
+func (b *Backoff) Duration() time.Duration {
+ d := b.ForAttempt(float64(atomic.AddUint64(&b.attempt, 1) - 1))
+ return d
+}
+
+const maxInt64 = float64(math.MaxInt64 - 512)
+
+// ForAttempt returns the duration for a specific attempt. This is useful if
+// you have a large number of independent Backoffs, but don't want use
+// unnecessary memory storing the Backoff parameters per Backoff. The first
+// attempt should be 0.
+//
+// ForAttempt is concurrent-safe.
+func (b *Backoff) ForAttempt(attempt float64) time.Duration {
+ // Zero-values are nonsensical, so we use
+ // them to apply defaults
+ min := b.Min
+ if min <= 0 {
+ min = 100 * time.Millisecond
+ }
+ max := b.Max
+ if max <= 0 {
+ max = 10 * time.Second
+ }
+ if min >= max {
+ // short-circuit
+ return max
+ }
+ factor := b.Factor
+ if factor <= 0 {
+ factor = 2
+ }
+ //calculate this duration
+ minf := float64(min)
+ durf := minf * math.Pow(factor, attempt)
+ if b.Jitter {
+ durf = rand.Float64()*(durf-minf) + minf
+ }
+ //ensure float64 wont overflow int64
+ if durf > maxInt64 {
+ return max
+ }
+ dur := time.Duration(durf)
+ //keep within bounds
+ if dur < min {
+ return min
+ }
+ if dur > max {
+ return max
+ }
+ return dur
+}
+
+// Reset restarts the current attempt counter at zero.
+func (b *Backoff) Reset() {
+ atomic.StoreUint64(&b.attempt, 0)
+}
+
+// Attempt returns the current attempt counter value.
+func (b *Backoff) Attempt() float64 {
+ return float64(atomic.LoadUint64(&b.attempt))
+}
+
+// Copy returns a backoff with equals constraints as the original
+func (b *Backoff) Copy() *Backoff {
+ return &Backoff{
+ Factor: b.Factor,
+ Jitter: b.Jitter,
+ Min: b.Min,
+ Max: b.Max,
+ }
+}