internal fun connectFailed(
    client: OkHttpClient,
    failedRoute: Route,
    failure: IOException,
  ) {
    // Tell the proxy selector when we fail to connect on a fresh connection.
    if (failedRoute.proxy.type() != Proxy.Type.DIRECT) {
      val address = failedRoute.address
      address.proxySelector.connectFailed(
        address.url.toUri(),

 *    we must send a `CONNECT` request, and handle authorization challenges from the proxy.
 *  * Optional [TLS handshake][connectTls].
 *
 * Each step may fail. If a retry is possible, a new instance is created with the next plan, which
 * will be configured differently.
 */
class ConnectPlan(
  private val taskRunner: TaskRunner,
  private val connectionPool: RealConnectionPool,

    connection.calls.add(CallReference(this, callStackTrace))
  }

  /**
   * Releases resources held with the request or response of [exchange]. This should be called when
   * the request completes normally or when it fails due to an exception, in which case [e] should
   * be non-null.
   *
   * If the exchange was canceled or timed out, this will wrap [e] in an exception that provides

   *
   * The deadline to respond to this ping attempts to limit the cost of being wrong. If it is too
   * long, streams created while we await the pong will reuse broken connections and inevitably
   * fail. If it is too short, slow connections will be marked as failed and extra TCP and TLS
   * handshakes will be required.
   *
   * The deadline is currently hardcoded. We may make this configurable in the future!
   */

      ) ?: return null

    // If we coalesced our connection, remember the replaced connection's route. That way if the
    // coalesced connection later fails we don't waste a valid route.
    if (planToReplace != null) {
      nextRouteToTry = planToReplace.route
      planToReplace.closeQuietly()
    }

    connectionUser.connectionAcquired(result)

    plan0.tcpConnectThrowable = IOException("boom!")
    val plan1 = routePlanner.addPlan()
    plan1.tcpConnectDelayNanos = 270.ms // Connect fail at time = 520 ms.
    plan1.tcpConnectThrowable = IOException("boom!")
    val plan2 = routePlanner.addPlan()
    plan2.tcpConnectDelayNanos = 30.ms // Connect fail at time = 530 ms.
    plan2.tcpConnectThrowable = IOException("boom!")
    val plan3 = routePlanner.addPlan()

    assertThat(rstStream.streamId).isEqualTo(2)
    assertThat(rstStream.errorCode).isEqualTo(ErrorCode.CANCEL)
  }

  /**
   * When writing a set of headers fails due to an `IOException`, make sure the writer is left
   * in a consistent state so the next writer also gets an `IOException` also instead of
   * something worse (like an [IllegalStateException].
   *
   *