connection: RealConnection,
  ): Boolean {
    val addressState = addressStates[connection.route.address] ?: return true
    val capacityWithoutIt = addressState.concurrentCallCapacity - connection.allocationLimit
    return capacityWithoutIt >= addressState.policy.minimumConcurrentCalls
  }

  /**
   * Prunes any leaked calls and then returns the number of remaining live calls on [connection].