// https://daniel.haxx.se/blog/2016/08/18/http2-connection-coalescing/

    // 1. This connection must be HTTP/2.
    if (http2Connection == null) return false

    // 2. The routes must share an IP address.
    if (routes == null || !routeMatchesAny(routes)) return false

    // 3. This connection's server certificate's must cover the new host.
    if (address.hostnameVerifier !== OkHostnameVerifier) return false

    automatically retry on an unshared connection.
 *  Fix: Don't crash if a TLS tunnel's response body is truncated.
 *  Fix: Don't track unusable routes beyond their usefulness. We had a bug where we could track
    certain bad routes indefinitely; now we only track the ones that could be necessary.
 *  Fix: Defer proxy selection until a proxy is required. This saves calls to `ProxySelector` on

    val selection = routeSelector.next()
    dns.assertRequests(uriHost)
    val routes = selection.routes
    assertRoute(routes[0], address, Proxy.NO_PROXY, dns.lookup(uriHost, 0), uriPort)
    assertRoute(routes[1], address, Proxy.NO_PROXY, dns.lookup(uriHost, 1), uriPort)
    assertThat(selection.next()).isSameAs(routes[0])
    assertThat(selection.next()).isSameAs(routes[1])
    assertThat(selection.hasNext()).isFalse()

      pingIntervalMillis = pingIntervalMillis,
      retryOnConnectionFailure = retryOnConnectionFailure,
      user = user,
      routePlanner = routePlanner,
      route = route,
      routes = routes,
      attempt = attempt,
      tunnelRequest = tunnelRequest,
      connectionSpecIndex = connectionSpecIndex,
      isTlsFallback = isTlsFallback,
    )
  }

    assertFailsWith<InterruptedIOException> {
      // If this succeeds, too many requests were made.
      client.newCall(request).execute()
    }
  }

  /**
   * Make a request with two routes. The first route will time out because it's connecting to a
   * special address that never connects. The automatic retry will succeed.
   */
  @Test
  fun connectTimeoutsAttemptsAlternateRoute() {

    // Compute the next set of routes to attempt.
    val routes = mutableListOf<Route>()
    while (hasNextProxy()) {
      // Postponed routes are always tried last. For example, if we have 2 proxies and all the
      // routes for proxy1 should be postponed, we'll move to proxy2. Only after we've exhausted
      // all the good routes will we attempt the postponed routes.
      val proxy = nextProxy()

    assertThat(response.body.string()).isEqualTo("abc")
    assertThat(server.takeRequest().sequenceNumber).isEqualTo(0)

    // Note that although we have two routes available, we only use one. The retry is permitted
    // because there are routes available, but it chooses the existing connection since it isn't
    // yet considered unhealthy.
    assertThat(server.takeRequest().sequenceNumber).isEqualTo(1)
  }

    planToReplace: ConnectPlan? = null,
    routes: List<Route>? = null,
  ): ReusePlan? {
    val result =
      connectionPool.callAcquirePooledConnection(
        doExtensiveHealthChecks = connectionUser.doExtensiveHealthChecks(),
        address = address,
        connectionUser = connectionUser,
        routes = routes,
        requireMultiplexed = planToReplace != null && planToReplace.isReady,

    if (requestSendStarted && requestIsOneShot(e, userRequest)) return false

    // This exception is fatal.
    if (!isRecoverable(e, requestSendStarted)) return false

    // No more routes to attempt.
    if (!call.retryAfterFailure()) return false

    // For failure recovery, use the same route selector with a new connection.
    return true
  }

  private fun requestIsOneShot(

release is the version name.


[Ktor]: https://ktor.io/
[assertk]: https://github.com/willowtreeapps/assertk
[graalvm]: https://www.graalvm.org/
[graalvm_21]: https://www.graalvm.org/release-notes/21_0/
[graalvm_22]: https://www.graalvm.org/release-notes/22_2/
[idna_15_1_0]: https://www.unicode.org/reports/tr46/#Modifications
[kotlin_1_4_20]: https://github.com/JetBrains/kotlin/releases/tag/v1.4.20