Implement Jitter()

cluster/bootstrap.go

@@ -112,7 +112,7 @@ func (b *Bootstrapper) SetBasicAuth(username, password string) {
 func (b *Bootstrapper) Boot(id, raftAddr string, done func() bool, timeout time.Duration) error {
 	timeoutT := time.NewTimer(timeout)
 	defer timeoutT.Stop()
-	tickerT := time.NewTimer(jitter(time.Millisecond))
+	tickerT := time.NewTimer(random.Jitter(time.Millisecond))
 	defer tickerT.Stop()
 
 	for {
@@ -127,7 +127,7 @@ func (b *Bootstrapper) Boot(id, raftAddr string, done func() bool, timeout time.
 				b.setBootStatus(BootDone)
 				return nil
 			}
-			tickerT.Reset(jitter(b.Interval)) // Move to longer-period polling
+			tickerT.Reset(random.Jitter(b.Interval)) // Move to longer-period polling
 
 			targets, err := b.provider.Lookup()
 			if err != nil {
@@ -251,10 +251,3 @@ func (s *stringAddressProvider) Lookup() ([]string, error) {
 func NewAddressProviderString(ss []string) AddressProvider {
 	return &stringAddressProvider{ss}
 }
-
-// jitter adds a little bit of randomness to a given duration. This is
-// useful to prevent nodes across the cluster performing certain operations
-// all at the same time.
-func jitter(duration time.Duration) time.Duration {
-	return duration + time.Duration(random.Float64()*float64(duration))
-}

disco/service.go

@@ -76,7 +76,7 @@ func (s *Service) Register(id, apiAddr, addr string) (bool, string, error) {
 			return true, apiAddr, nil
 		}
 
-		time.Sleep(jitter(s.RegisterInterval))
+		time.Sleep(random.Jitter(s.RegisterInterval))
 	}
 }
 
@@ -138,7 +138,3 @@ func (s *Service) updateContact(t time.Time) {
 	defer s.mu.Unlock()
 	s.lastContact = t
 }
-
-func jitter(duration time.Duration) time.Duration {
-	return duration + time.Duration(random.Float64()*float64(duration))
-}

random/random.go

@@ -41,3 +41,10 @@ func Intn(n int) int {
 	defer mu.Unlock()
 	return r.Intn(n)
 }
+
+// Jitter adds a little bit of randomness to a given duration. This is
+// useful to prevent nodes across the cluster performing certain operations
+// all at the same time.
+func Jitter(d time.Duration) time.Duration {
+	return d + time.Duration(Float64()*float64(d))
+}