private var coordinatorWakeUpAt = 0L

  /**
   * When we need a new thread to run tasks, we call [Backend.execute]. A few microseconds later we
   * expect a newly-started thread to call [Runnable.run]. We shouldn't request new threads until
   * the already-requested ones are in service, otherwise we might create more threads than we need.
   *
   * We use [executeCallCount] and [runCallCount] to defend against starting more threads than we

 * test what OkHttp does when both are reachable, or if only one is reachable.
 *
 * This test only runs on host machines that have both IPv4 and IPv6 addresses for localhost.
 */
@Timeout(30)
class FastFallbackTest {
  @RegisterExtension
  val clientTestRule = OkHttpClientTestRule()

  // Don't use JUnit 5 test rules for these; otherwise we can't bind them to a single local IP.

    try {
      networkResponse = chain.proceed(networkRequest)
    } finally {
      // If we're crashing on I/O or otherwise, don't leak the cache body.
      if (networkResponse == null && cacheCandidate != null) {
        cacheCandidate.body.closeQuietly()
      }
    }

    // If we have a cache response too, then we're doing a conditional get.
    if (cacheResponse != null) {

      } catch (_: IOException) {
        // The cache cannot be written.
      }
      return null
    }

    if (requestMethod != "GET") {
      // Don't cache non-GET responses. We're technically allowed to cache HEAD requests and some
      // POST requests, but the complexity of doing so is high and the benefit is low.
      return null
    }

    if (response.hasVaryAll()) {
      return null

 * typically false on Windows.
 *
 * If this returns false we won't permit simultaneous reads and writes. When writes commit we need
 * to delete the previous snapshots, and that won't succeed if the file is open. (We do permit
 * multiple simultaneous reads.)
 *
 * @param file a file in the directory to check. This file shouldn't already exist!
 */

}

/**
 * Returns true if new reads and writes should be attempted on this.
 *
 * Unfortunately Java's networking APIs don't offer a good health check, so we go on our own by
 * attempting to read with a short timeout. If the fails immediately we know the socket is
 * unhealthy.
 *
 * @param source the source used to read bytes from the socket.
 */
internal fun Socket.isHealthy(source: BufferedSource): Boolean {

        }
        .build()

    executeSynchronously(request)
      .assertBody("body")

    assertThat(client.routeDatabase.failedRoutes).isEmpty()
    // TODO check if we expect a second request to server1, before attempting server2
    assertThat(server1.requestCount).isEqualTo(2)
    assertThat(server2.requestCount).isEqualTo(1)

 *  Breaking: Drop support for Kotlin Multiplatform.

    We planned to support multiplatform in OkHttp 5.0, but after building it, we weren't happy with
    the implementation trade-offs. We can't use our HTTP client engine on Kotlin/JS, and we weren't
    prepared to build a TLS API for Kotlin/Native.

    We'd prefer a multiplatform HTTP client API that's backed by OkHttp on Android and JVM, and

      .build()
  }

  private fun buildServerSslSocketFactory(): SSLSocketFactory {
    // The test uses JDK default SSL Context instead of the Platform provided one
    // as Conscrypt seems to have some differences, we only want to test client side here.
    return try {
      val keyManager =
        newKeyManager(
          null,
          serverCert,
          serverIntermediateCa.certificate,
        )

      if (retryRoute != null) {
        // Lock in the route because retryRoute() is racy and we don't want to call it twice.
        nextRouteToTry = retryRoute
        return true
      }
    }

    // If we have a routes left, use 'em.
    if (routeSelection?.hasNext() == true) return true

    // If we haven't initialized the route selector yet, assume it'll have at least one route.