* and duplex calls where the timeout only applies to the initial setup.
   */
  fun timeoutEarlyExit() {
    check(!timeoutEarlyExit)
    timeoutEarlyExit = true
    timeout.exit()
  }

  fun upgradeToSocket() {
    timeoutEarlyExit()

    withLock {
      check(exchange != null)
      check(!socketSinkOpen && !socketSourceOpen)
      check(!requestBodyOpen)