reconciler: Fix max backoff calculation

With enough retry attempts the duration becomes too large
and overflows on conversion to time.Duration leading to negative
durations. Fix this by checking the bounds with a float64 before
conversion.

Signed-off-by: Jussi Maki <[email protected]>

reconciler/retries.go

@@ -18,11 +18,11 @@ type exponentialBackoff struct {
 }
 
 func (e *exponentialBackoff) Duration(attempt int) time.Duration {
-	dur := time.Duration(float64(e.min) * math.Pow(2, float64(attempt)))
-	if dur > e.max {
-		dur = e.max
+	dur := float64(e.min) * math.Pow(2, float64(attempt))
+	if dur > float64(e.max) {
+		return e.max
 	}
-	return dur
+	return time.Duration(dur)
 }
 
 func newRetries(minDuration, maxDuration time.Duration, objectToKey func(any) index.Key) *retries {

reconciler/retries_test.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 
 	"github.com/cilium/statedb/index"
 )
@@ -102,5 +103,18 @@ func TestRetries(t *testing.T) {
 	}
 	_, ok = rq.Top()
 	assert.False(t, ok)
+}
+
+func TestExponentialBackoff(t *testing.T) {
+	backoff := exponentialBackoff{
+		min: time.Millisecond,
+		max: time.Second,
+	}
 
+	for i := 0; i < 1000; i++ {
+		dur := backoff.Duration(i)
+		require.GreaterOrEqual(t, dur, backoff.min)
+		require.LessOrEqual(t, dur, backoff.max)
+	}
+	require.Equal(t, backoff.Duration(0)*2, backoff.Duration(1))
 }