### EventListener.Factory

In the preceding example we used a field, `callStartNanos`, to track the elapsed time of each event. This is handy, but it won’t work if multiple calls are executing concurrently. To accommodate this, use a `Factory` to create a new `EventListener` instance for each `Call`. This allows each listener to keep call-specific state.

    ): Relay {
      val randomAccessFile = RandomAccessFile(file, "rw")
      val result = Relay(randomAccessFile, upstream, 0L, metadata, bufferMaxSize)

      // Write a dirty header. That way if we crash we won't attempt to recover this.
      randomAccessFile.setLength(0L)
      result.writeHeader(PREFIX_DIRTY, -1L, -1L)

      return result
    }

    /**

saves bandwidth but it costs CPU and memory! If you run into a problem you may need to adjust or
disable the `permessage-deflate` compression settings on your server.

Note that OkHttp won't use compression when sending messages smaller than 1 KiB.

 *  Fix: Don't crash when the URL hostname contains an underscore on Android.

          .build(),
      )
    }
  }

  private fun testServerClosesOutput(socketPolicy: SocketPolicy) {
    server.enqueue(
      MockResponse(
        body = "This connection won't pool properly",
        socketPolicy = socketPolicy,
      ),
    )
    val responseAfter = MockResponse(body = "This comes after a busted connection")
    server.enqueue(responseAfter)

 * this class separates _allocations_ from _streams_. An allocation is created by a call, used for
 * one or more streams, and then released. An allocated connection won't be stolen by other calls
 * while a redirect or authorization challenge is being handled.
 *
 * When the maximum concurrent streams limit is reduced, some allocations will be rescinded.

 *
 * ## Web Socket Lifecycle
 *
 * Upon normal operation each web socket progresses through a sequence of states:
 *
 *  * **Connecting:** the initial state of each web socket. Messages may be enqueued but they won't
 *    be transmitted until the web socket is open.
 *
 *  * **Open:** the web socket has been accepted by the remote peer and is fully operational.
 *    Messages in either direction are enqueued for immediate transmission.

    assertThat(server.takeRequest().sequenceNumber)
      .isEqualTo(0) // Fresh connection.
    assertThat(client.connectionPool.connectionCount()).isEqualTo(2)
  }

  /**
   * Won't coalesce if we can't clean certs e.g. a dev setup.
   */
  @Test
  fun redirectWithDevSetup() {
    val trustManager: X509TrustManager =
      object : X509TrustManager {
        override fun checkClientTrusted(

    assertThat(synStream.outFinished).isFalse()
    val ping = peer.takeFrame()
    assertThat(ping.type).isEqualTo(Http2.TYPE_PING)
  }

  /**
   * Test that the client sends a RST_STREAM if doing so won't disrupt the output stream.
   */
  @Test fun clientClosesClientInputStream() {
    // Write the mocking script.
    peer.sendFrame().settings(Settings())
    peer.acceptFrame() // ACK

0EBA          ; valid                                  # 12.0 LAO SIGN PALI VIRAMA
0EBB..0EBD    ; valid                                  # 1.1  LAO VOWEL SIGN MAI KON..LAO SEMIVOWEL SIGN NYO
0EBE..0EBF    ; disallowed                             # NA   <reserved-0EBE>..<reserved-0EBF>
0EC0..0EC4    ; valid                                  # 1.1  LAO VOWEL SIGN E..LAO VOWEL SIGN AI

        }

        if (connectResult.isSuccess) {
          // We have a connected TCP connection. Cancel and defer the racing connects that all lost.
          cancelInFlightConnects()

          // Finish connecting. We won't have to if the winner is from the connection pool.
          if (!connectResult.plan.isReady) {
            connectResult = connectResult.plan.connectTlsEtc()
          }

          if (connectResult.isSuccess) {