backoff strategy factory constructors take random seeds instead of random sources

backoff.go

@@ -3,6 +3,7 @@ package discovery
 import (
 	"math"
 	"math/rand"
+	"sync"
 	"time"
 )
 
@@ -90,7 +91,8 @@ func (b *fixedBackoff) Reset() {}
 // timeUnits are the units of time the polynomial is evaluated in
 // polyCoefs is the array of polynomial coefficients from [c0, c1, ... cn]
 func NewPolynomialBackoff(min, max time.Duration, jitter Jitter,
-	timeUnits time.Duration, polyCoefs []float64, rng *rand.Rand) BackoffFactory {
+	timeUnits time.Duration, polyCoefs []float64, rngSeed int64) BackoffFactory {
+	rng := rand.New(&lockedSource{src: rand.NewSource(rngSeed)})
 	return func() BackoffStrategy {
 		return &polynomialBackoff{
 			attemptBackoff: attemptBackoff{
@@ -138,7 +140,8 @@ func (b *polynomialBackoff) Delay() time.Duration {
 // jitter is the function for adding randomness around the backoff
 // timeUnits are the units of time the base^x is evaluated in
 func NewExponentialBackoff(min, max time.Duration, jitter Jitter,
-	timeUnits time.Duration, base float64, offset time.Duration, rng *rand.Rand) BackoffFactory {
+	timeUnits time.Duration, base float64, offset time.Duration, rngSeed int64) BackoffFactory {
+	rng := rand.New(&lockedSource{src: rand.NewSource(rngSeed)})
 	return func() BackoffStrategy {
 		return &exponentialBackoff{
 			attemptBackoff: attemptBackoff{
@@ -173,7 +176,8 @@ func (b *exponentialBackoff) Delay() time.Duration {
 // NewExponentialDecorrelatedJitter creates a BackoffFactory with backoff of the roughly of the form base^x where x is the attempt number.
 // Delays start at the minimum duration and after each attempt delay = rand(min, delay * base), bounded by the max
 // See https://aws.amazon.com/blogs/architecture/exponential-backoff-and-jitter/ for more information
-func NewExponentialDecorrelatedJitter(min, max time.Duration, base float64, rng *rand.Rand) BackoffFactory {
+func NewExponentialDecorrelatedJitter(min, max time.Duration, base float64, rngSeed int64) BackoffFactory {
+	rng := rand.New(&lockedSource{src: rand.NewSource(rngSeed)})
 	return func() BackoffStrategy {
 		return &exponentialDecorrelatedJitter{
 			randomizedBackoff: randomizedBackoff{
@@ -204,3 +208,21 @@ func (b *exponentialDecorrelatedJitter) Delay() time.Duration {
 }
 
 func (b *exponentialDecorrelatedJitter) Reset() { b.lastDelay = 0 }
+
+type lockedSource struct {
+	lk  sync.Mutex
+	src rand.Source
+}
+
+func (r *lockedSource) Int63() (n int64) {
+	r.lk.Lock()
+	n = r.src.Int63()
+	r.lk.Unlock()
+	return
+}
+
+func (r *lockedSource) Seed(seed int64) {
+	r.lk.Lock()
+	r.src.Seed(seed)
+	r.lk.Unlock()
+}

backoff_test.go

@@ -39,8 +39,7 @@ func TestFixedBackoff(t *testing.T) {
 }
 
 func TestPolynomialBackoff(t *testing.T) {
-	rng := rand.New(rand.NewSource(0))
-	bkf := NewPolynomialBackoff(time.Second, time.Second*33, NoJitter, time.Second, []float64{0.5, 2, 3}, rng)
+	bkf := NewPolynomialBackoff(time.Second, time.Second*33, NoJitter, time.Second, []float64{0.5, 2, 3}, 0)
 	b1 := bkf()
 	b2 := bkf()
 
@@ -59,8 +58,7 @@ func TestPolynomialBackoff(t *testing.T) {
 }
 
 func TestExponentialBackoff(t *testing.T) {
-	rng := rand.New(rand.NewSource(0))
-	bkf := NewExponentialBackoff(time.Millisecond*650, time.Second*7, NoJitter, time.Second, 1.5, -time.Millisecond*400, rng)
+	bkf := NewExponentialBackoff(time.Millisecond*650, time.Second*7, NoJitter, time.Second, 1.5, -time.Millisecond*400, 0)
 	b1 := bkf()
 	b2 := bkf()
 

backoffcache_test.go

@@ -67,7 +67,7 @@ func TestBackoffDiscoverySingleBackoff(t *testing.T) {
 	d2 := &mockDiscoveryClient{h2, discServer}
 
 	bkf := NewExponentialBackoff(time.Millisecond*100, time.Second*10, NoJitter,
-		time.Millisecond*100, 2.5, 0, nil)
+		time.Millisecond*100, 2.5, 0, 0)
 	dCache, err := NewBackoffDiscovery(d1, bkf)
 	if err != nil {
 		t.Fatal(err)
@@ -101,7 +101,7 @@ func TestBackoffDiscoveryMultipleBackoff(t *testing.T) {
 
 	// Startup delay is 0ms. First backoff after finding data is 100ms, second backoff is 250ms.
 	bkf := NewExponentialBackoff(time.Millisecond*100, time.Second*10, NoJitter,
-		time.Millisecond*100, 2.5, 0, nil)
+		time.Millisecond*100, 2.5, 0, 0)
 	dCache, err := NewBackoffDiscovery(d1, bkf)
 	if err != nil {
 		t.Fatal(err)