} catch (e: IOException) {
      eventListener.responseFailed(call, e)
      trackFailure(e)
      throw e
    }
  }

  @Throws(IOException::class)
  fun peekTrailers(): Headers? = codec.peekTrailers()

  fun upgradeToSocket(): Socket {
    call.timeoutEarlyExit()
    (codec.carrier as RealConnection).useAsSocket()

    eventListener.requestBodyStart(call)

      !response.promisesBody() -> 0L
      else -> response.headersContentLength()
    }

  override fun openResponseBodySource(response: Response): Source = stream!!.source

  override fun peekTrailers(): Headers? = stream!!.peekTrailers()

  override fun cancel() {
    canceled = true
    stream?.closeLater(ErrorCode.CANCEL)
  }

  companion object {
    private const val CONNECTION = "connection"

  @Throws(IOException::class)
  fun openResponseBodySource(response: Response): Source

  /** Returns the trailers after the HTTP response if they're ready. May be empty. */
  @Throws(IOException::class)
  fun peekTrailers(): Headers?

  /**
   * Cancel this stream. Resources held by this stream will be cleaned up, though not synchronously.
   * That may happen later by the connection pool thread.
   */
  fun cancel()

  /**

            response
              .newBuilder()
              .body(responseBody)
              .trailers(
                object : TrailersSource {
                  override fun peek() = exchange.peekTrailers()

                  override fun get(): Headers {
                    val source = responseBody.source()
                    if (source.isOpen) {
                      source.skipAll()
                    }

    val stream = connection.newStream(headerEntries("a", "artichaut"), false)
    connection.writePingAndAwaitPong()
    assertThat(stream.takeHeaders()).isEqualTo(headersOf("headers", "bam"))
    assertThat(stream.peekTrailers()).isEqualTo(Headers.EMPTY)
    assertThat(connection.openStreamCount()).isEqualTo(0)

    // Verify the peer received what was expected.
    val synStream = peer.takeFrame()

          newFixedLengthSource(response.request.url, contentLength)
        } else {
          newUnknownLengthSource(response.request.url)
        }
      }
    }

  override fun peekTrailers(): Headers? {
    if (trailers === TRAILERS_RESPONSE_BODY_TRUNCATED) {
      throw IOException("Trailers cannot be read because the response body was truncated")
    }

   *
   * @throws IOException if the trailers cannot be loaded, such as if the network connection is
   *     dropped.
   */
  @Throws(IOException::class)
  fun peekTrailers(): Headers? = trailersSource.peek()

  /**
   * Peeks up to [byteCount] bytes from the response body and returns them as a new response

	public final fun networkResponse ()Lokhttp3/Response;
	public final fun newBuilder ()Lokhttp3/Response$Builder;
	public final fun peekBody (J)Lokhttp3/ResponseBody;
	public final fun peekTrailers ()Lokhttp3/Headers;
	public final fun priorResponse ()Lokhttp3/Response;
	public final fun protocol ()Lokhttp3/Protocol;
	public final fun receivedResponseAtMillis ()J
	public final fun request ()Lokhttp3/Request;

	public final fun networkResponse ()Lokhttp3/Response;
	public final fun newBuilder ()Lokhttp3/Response$Builder;
	public final fun peekBody (J)Lokhttp3/ResponseBody;
	public final fun peekTrailers ()Lokhttp3/Headers;
	public final fun priorResponse ()Lokhttp3/Response;
	public final fun protocol ()Lokhttp3/Protocol;
	public final fun receivedResponseAtMillis ()J
	public final fun request ()Lokhttp3/Request;