dispatcher.maxRequests = 2
    client.newCall(newRequest("http://a/1")).enqueue(callback)
    client.newCall(newRequest("http://b/1")).enqueue(callback)
    client.newCall(newRequest("http://c/1")).enqueue(callback)
    client.newCall(newRequest("http://a/2")).enqueue(callback)
    client.newCall(newRequest("http://b/2")).enqueue(callback)

    val dispatcherQueueStartC1 = eventRecorder.removeUpToEvent<DispatcherQueueStart>()

        ).build()

    // Set up a same-connection retry.
    serverIpv4.enqueue(
      MockResponse
        .Builder()
        .onRequestStart(CloseStream(ErrorCode.REFUSED_STREAM.httpCode))
        .build(),
    )
    serverIpv4.enqueue(
      MockResponse(body = "this was the 2nd request on IPv4"),
    )
    serverIpv6.enqueue(
      MockResponse(body = "unexpected call to IPv6"),
    )

  }

  @Test
  fun http2OneBadHostOneGoodRetryOnConnectionFailure() {
    enableProtocol(Protocol.HTTP_2)

    val request = Request(server1.url("/"))

    server1.enqueue(refusedStream)
    server1.enqueue(refusedStream)
    server2.enqueue(bodyResponse)

    dns[server1.hostName] = listOf(ipv6, ipv4)
    socketFactory[ipv6] = server1.socketAddress
    socketFactory[ipv4] = server2.socketAddress

    client =

   */
  public void enqueue(Event<L> event) {
    enqueueHelper(event, event);
  }

  /**
   * Enqueues an event to be run on currently known listeners, with a label.
   *
   * @param event the callback to execute on {@link #dispatch}
   * @param label a description of the event to use in the case of an error
   */
  public void enqueue(Event<L> event, String label) {
    enqueueHelper(event, label);

    // If take() returned because we're shutting down, then enqueue another dead letter so that any
    // other threads waiting on take() will also return.
    if (result == DEAD_LETTER) responseQueue.add(DEAD_LETTER)

    return result
  }

  public override fun peek(): MockResponse = responseQueue.peek() ?: failFastResponse ?: super.peek()

  public open fun enqueue(response: MockResponse) {
    responseQueue.add(response)
  }

          call: Call,
          response: Response,
        ) {
          response.close()
        }
      }
    repeat(10_000) {
      okhttp.newCall(Request.Builder().url(server.url("/")).build()).enqueue(callback)
    }
    okhttp.dispatcher.executorService.shutdown()
  }

 *    socket will continue to transmit already-enqueued messages but will refuse to enqueue new
 *    ones.
 *
 *  * **Closed:** the web socket has transmitted all of its messages and has received all messages
 *    from the peer.
 *
 * Web sockets may fail due to HTTP upgrade problems, connectivity problems, or if either peer
 * chooses to short-circuit the graceful shutdown process:
 *

  @Test
  fun connectionPooling_Async() {
    server.enqueue(MockResponse(body = "abc"))
    server.enqueue(MockResponse(body = "def"))
    server.enqueue(MockResponse(body = "ghi"))
    client.newCall(Request.Builder().url(server.url("/a")).build()).enqueue(callback)
    callback.await(server.url("/a")).assertBody("abc")
    client.newCall(Request.Builder().url(server.url("/b")).build()).enqueue(callback)

      if (existingCall.host == host) return existingCall
    }
    return null
  }

  /**
   * Cancel all calls currently enqueued or executing. Includes calls executed both
   * [synchronously][Call.execute] and [asynchronously][Call.enqueue].
   */
  @Synchronized
  fun cancelAll() {
    for (call in readyAsyncCalls) {
      call.call.cancel()
    }
    for (call in runningAsyncCalls) {

   * Attempts to remove a single frame from a queue and send it. This prefers to write urgent pongs
   * before less urgent messages and close frames. For example, it's possible that a caller will
   * enqueue messages followed by pongs, but this sends pongs followed by messages. Pongs are always
   * written in the order they were enqueued.
   *
   * If a frame cannot be sent - because there are none enqueued or because the web socket is not