manager.addListener(listener, directExecutor());
    assertState(manager, Service.State.NEW, a, b);
    assertFalse(manager.isHealthy());
    manager.startAsync().awaitHealthy();
    assertState(manager, Service.State.RUNNING, a, b);
    assertTrue(manager.isHealthy());
    assertTrue(listener.healthyCalled);
    assertFalse(listener.stoppedCalled);
    assertTrue(listener.failedServices.isEmpty());

    }

    val http2Connection = this.http2Connection
    if (http2Connection != null) {
      return http2Connection.isHealthy(nowNs)
    }

    val idleDurationNs = withLock { nowNs - idleAtNs }
    if (idleDurationNs >= IDLE_CONNECTION_HEALTHY_NS && doExtensiveChecks) {
      return javaNetSocket.isHealthy(socket.source)
    }

    return true
  }

  /** Refuse incoming streams. */

 * 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 =
  try {
    val readTimeout = soTimeout
    try {
      soTimeout = 1
      !source.exhausted()
    } finally {
      soTimeout = readTimeout
    }

  private fun waitForConnectionShutdown(connection: RealConnection?) {
    if (connection!!.isHealthy(false)) {
      Thread.sleep(100L)
    }
    if (connection.isHealthy(false)) {
      Thread.sleep(2000L)
    }
    if (connection.isHealthy(false)) {
      throw TimeoutException("connection didn't shutdown within timeout")
    }
  }

  /**

    // When the timeout is sent the connection doesn't immediately go unhealthy.
    assertThat(connection.isHealthy(System.nanoTime())).isTrue()

    // But if the ping doesn't arrive, the connection goes unhealthy.
    Thread.sleep(TimeUnit.NANOSECONDS.toMillis(Http2Connection.DEGRADED_PONG_TIMEOUT_NS.toLong()))
    assertThat(connection.isHealthy(System.nanoTime())).isFalse()

    // When a pong does arrive, the connection becomes healthy again.

      withLock {
        if (isShutdown) {
          throw ConnectionShutdownException()
        }
        okHttpSettings.merge(settings)
      }
      writer.settings(settings)
    }
  }

  fun isHealthy(nowNs: Long): Boolean {
    withLock {
      if (isShutdown) return false

      // A degraded pong is overdue.
      if (degradedPongsReceived < degradedPingsSent && nowNs >= degradedPongDeadlineNs) return false