Various performance and correctness improvements.

transport/retry.go

@@ -9,12 +9,24 @@ import (
 type RetryManager struct {
 	config     *RetryConfig
 	retryCount int
+	saturation int
 }
 
 func NewRetryManager(config *RetryConfig) *RetryManager {
+	// saturationCount: retry count at which base delay meets or exceeds MaxDelay.
+	// Conservative by one to preserve jitter variance near the boundary.
+	saturation := 0
+	if config != nil &&
+		config.InitialDelay > 0 &&
+		config.InitialDelay <= config.MaxDelay {
+		ratio := float64(config.MaxDelay) / float64(config.InitialDelay)
+		saturation = int(math.Ceil(math.Log2(ratio))) + 2
+	}
+
 	return &RetryManager{
 		config:     config,
 		retryCount: 0,
+		saturation: saturation,
 	}
 }
 
@@ -40,8 +52,18 @@ func (r *RetryManager) CalculateDelay() time.Duration {
 		return 0
 	}
 
+	// if saturation is reached, calculated backoff will always be higher than
+	// the maximum delay
+	if r.config != nil && r.retryCount >= r.saturation {
+		return r.config.MaxDelay
+	}
+
 	// Exponential backoff: InitialDelay * 2^(attempts-1)
-	backoffMultiplier := math.Pow(2, float64(r.retryCount-1))
+	shift := r.retryCount - 1
+	if shift > 62 {
+		shift = 62
+	} // prevent overflow
+	backoffMultiplier := float64(int64(1) << shift)
 	baseDelay := float64(r.config.InitialDelay) * backoffMultiplier
 
 	// Apply jitter: delay * (1 + jitterFactor * (random - 0.5))