*
 * Planning failures are not necessarily fatal. For example, even if we can't DNS lookup the first
 * proxy in a list, looking up a subsequent one may succeed.
 */
internal class FailedPlan(
  e: Throwable,
) : RoutePlanner.Plan {
  val result = RoutePlanner.ConnectResult(plan = this, throwable = e)

  override val isReady = false

  override fun connectTcp() = result

            routePlanner.plan()
          } catch (e: Throwable) {
            FailedPlan(e)
          }
        }
        else -> return null // Nothing further to try.
      }

    // Already connected. Return it immediately.
    if (plan.isReady) return ConnectResult(plan)

    // Already failed? Return it immediately.
    if (plan is FailedPlan) return plan.result

    // Connect TCP asynchronously.