op-service/backoff: Refactor to use time.Duration instead of float/int. (#6823)

changed backoff/strategies.go and backoff/strategies_test.go, only types and a function changed

**Description**

No features added. Just refactored backoff package to allow only types from time.Duration on time related variables.

**Tests**

Only modified a single test to use time.Duration instead of int.

**Metadata**

- Fixes #[[Link to Issue](https://github.com/ethereum-optimism/optimism/issues/6730#issuecomment-1678950667)]
Co-authored-by: Rcontre360 <rcontreraspimentel@gmail.com>

op-node/sources/sync_client.go

@@ -131,9 +131,9 @@ func (s *SyncClient) eventLoop() {
 	s.log.Info("Starting sync client event loop")
 
 	backoffStrategy := &backoff.ExponentialStrategy{
-		Min:       1000,
-		Max:       20_000,
-		MaxJitter: 250,
+		Min:       1000 * time.Millisecond,
+		Max:       20_000 * time.Millisecond,
+		MaxJitter: 250 * time.Millisecond,
 	}
 
 	for {

op-service/backoff/strategies.go

@@ -16,35 +16,34 @@ type Strategy interface {
 // ExponentialStrategy performs exponential backoff. The exponential backoff
 // function is min(e.Min + (2^attempt * 1000) + randBetween(0, e.MaxJitter), e.Max)
 type ExponentialStrategy struct {
-	// Min is the minimum amount of time to wait between attempts in ms.
-	Min float64
+	// Min is the minimum amount of time to wait between attempts.
+	Min time.Duration
 
-	// Max is the maximum amount of time to wait between attempts in ms.
-	Max float64
+	// Max is the maximum amount of time to wait between attempts.
+	Max time.Duration
 
-	// MaxJitter is the maximum amount of random jitter to insert between
-	// attempts in ms.
-	MaxJitter int
+	// MaxJitter is the maximum amount of random jitter to insert between attempts.
+	MaxJitter time.Duration
 }
 
 func (e *ExponentialStrategy) Duration(attempt int) time.Duration {
-	var jitter int
+	var jitter time.Duration
 	if e.MaxJitter > 0 {
-		jitter = rand.Intn(e.MaxJitter)
+		jitter = time.Duration(rand.Int63n(e.MaxJitter.Nanoseconds()))
 	}
-	dur := e.Min + (math.Pow(2, float64(attempt)) * 1000)
-	dur += float64(jitter)
+	dur := e.Min + time.Duration(int(math.Pow(2, float64(attempt))*1000))*time.Millisecond
+	dur += jitter
 	if dur > e.Max {
-		return time.Millisecond * time.Duration(e.Max)
+		return e.Max
 	}
 
-	return time.Millisecond * time.Duration(dur)
+	return dur
 }
 
 func Exponential() Strategy {
 	return &ExponentialStrategy{
-		Max:       10000,
-		MaxJitter: 250,
+		Max:       time.Duration(10000 * time.Millisecond),
+		MaxJitter: time.Duration(250 * time.Millisecond),
 	}
 }
 

op-service/backoff/strategies_test.go

@@ -9,13 +9,13 @@ import (
 
 func TestExponential(t *testing.T) {
 	strategy := &ExponentialStrategy{
-		Min:       3000,
-		Max:       10000,
+		Min:       3000 * time.Millisecond,
+		Max:       10000 * time.Millisecond,
 		MaxJitter: 0,
 	}
 
-	durations := []int{4, 5, 7, 10, 10}
+	durations := []time.Duration{4, 5, 7, 10, 10}
 	for i, dur := range durations {
-		require.Equal(t, time.Millisecond*time.Duration(dur*1000), strategy.Duration(i))
+		require.Equal(t, dur*time.Second, strategy.Duration(i))
 	}
 }