Calculate exponential backoff iff current backoff is lower than maxBa…

…ckoff

config/retry.go

@@ -114,14 +114,19 @@ func (c *RetryConfig) RetryFunc() RetryFunc {
 			return false, 0
 		}
 
-		base := math.Pow(2, float64(retry))
-		sleep := time.Duration(base) * TimeDurationVal(c.Backoff)
-
+		baseSleep := TimeDurationVal(c.Backoff)
 		maxSleep := TimeDurationVal(c.MaxBackoff)
-		if maxSleep > 0 && maxSleep < sleep {
-			return true, maxSleep
+
+		if maxSleep > 0 {
+			attemptsTillMaxBackoff := int(math.Log2(maxSleep.Seconds() / baseSleep.Seconds()))
+			if retry > attemptsTillMaxBackoff {
+				return true, maxSleep
+			}
 		}
 
+		base := math.Pow(2, float64(retry))
+		sleep := time.Duration(base) * baseSleep
+
 		return true, sleep
 	}
 }

config/retry_test.go

@@ -127,6 +127,17 @@ func TestRetryFunc(t *testing.T) {
 			Bool(true),
 			TimeDuration(5 * time.Second),
 		},
+		{
+			"max backoff, attempt 100",
+			&RetryConfig{
+			Attempts:   Int(0),
+			Backoff:    TimeDuration(1 * time.Millisecond),
+			MaxBackoff: TimeDuration(2 * time.Millisecond),
+		},
+			Int(100),
+			Bool(true),
+			TimeDuration(2 * time.Millisecond),
+		},
 	}
 
 	for i, tc := range cases {