fn default_session_surb_balance_notify_period() -> Option<Duration>Expand description
Transport-layer default for the SURB balance notification period; this is the effective default
for SessionGlobalConfig::surb_balance_notify_period (15s). It deliberately overrides the
lower-level fallback in SessionManagerConfig (whose own field default is 60s) with a tighter
15s cadence, so the Entry’s dead-reckoned estimate of the Exit’s SURB buffer is corrected often
enough to keep the SURB balancer from under-producing (and starving the Exit) under drift,
without the per-session keep-alive overhead of the previous 2s cadence. The 1s floor is enforced
downstream by SessionManager::new (MIN_SURB_BUFFER_NOTIFICATION_PERIOD).