import okhttp3.internal.ws.WebSocketProtocol.OPCODE_CONTINUATION
import okhttp3.internal.ws.WebSocketProtocol.OPCODE_CONTROL_CLOSE
import okhttp3.internal.ws.WebSocketProtocol.OPCODE_CONTROL_PING
import okhttp3.internal.ws.WebSocketProtocol.OPCODE_CONTROL_PONG
import okhttp3.internal.ws.WebSocketProtocol.OPCODE_FLAG_CONTROL
import okhttp3.internal.ws.WebSocketProtocol.OPCODE_TEXT
import okhttp3.internal.ws.WebSocketProtocol.PAYLOAD_BYTE_MAX

      awaitingPong = true
    }

    if (failedPing != -1) {
      failWebSocket(
        e =
          SocketTimeoutException(
            "sent ping but didn't receive pong within " +
              "${pingIntervalMillis}ms (after ${failedPing - 1} successful ping/pongs)",
          ),
        isWriter = true,
      )
      return
    }

    try {
      writer.writePing(ByteString.EMPTY)

    val settings1 = Settings()
    settings1[Settings.MAX_CONCURRENT_STREAMS] = maxConcurrentStreams
    peer.sendFrame().settings(settings1)
    peer.acceptFrame() // ACK
    peer.sendFrame().ping(false, 2, 0)
    peer.acceptFrame() // PING
    peer.play()

    // Play it back.
    val connection =
      Http2Connection.Builder(true, TaskRunner.INSTANCE)
        .socket(peer.openSocket())

    the request already contains an `Accept` header.

 *  Fix: Don't crash with a `NullPointerException` if a server sends a close while we're sending a
    ping. OkHttp had a race condition bug.


## Version 4.6.0

_2020-04-28_

 *  Fix: Follow HTTP 307 and 308 redirects on methods other than GET and POST. We're reluctant to

    Previously if you configured a ping interval that would cause OkHttp to send
    pings, but it did not track whether the reply pongs were received. With this
    update OkHttp requires that every ping receive a response: if it does not
    the connection will be closed and the listener's `onFailure()` method will
    be called.

    Web sockets have always been had pings, but pings on HTTP/2 connections is

    newWebSocket()
    clientListener.assertOpen()
    clientListener.assertFailure(
      SocketTimeoutException::class.java,
      "sent ping but didn't receive pong within 500ms (after 0 successful ping/pongs)",
    )
    latch.countDown()
    val elapsedUntilFailure = System.nanoTime() - openAtNanos
    assertThat(TimeUnit.NANOSECONDS.toMillis(elapsedUntilFailure).toDouble())
      .isCloseTo(1000.0, 250.0)
  }

#### Do-stuff-later pool

Sometimes there's an action required like calling the application layer or responding to a ping, and the thread discovering the action is not the thread that should do the work. We enqueue a runnable on this executor and it gets handled by one of the executor's threads.

### Locks

      }

    /**
     * Sets the interval between HTTP/2 and web socket pings initiated by this client. Use this to
     * automatically send ping frames until either the connection fails or it is closed. This keeps
     * the connection alive and may detect connectivity failures.
     *
     * If the server does not respond to each ping with a pong within `interval`, this client will

    peer.acceptFrame() // PING
    peer.sendFrame().ping(true, 99, 0) // This pong is silently ignored.
    peer.sendFrame().ping(false, 4, 0)
    peer.acceptFrame() // PING
    peer.play()

    // Play it back.
    connect(peer)

    // Verify the peer received what was expected.
    val ping2 = peer.takeFrame()
    assertThat(ping2.payload1).isEqualTo(2)
    val ping4 = peer.takeFrame()

  internal const val OPCODE_TEXT = 0x1
  internal const val OPCODE_BINARY = 0x2

  internal const val OPCODE_CONTROL_CLOSE = 0x8
  internal const val OPCODE_CONTROL_PING = 0x9
  internal const val OPCODE_CONTROL_PONG = 0xa

  /**
   * Maximum length of frame payload. Larger payloads, if supported by the frame type, can use the
   * special values [PAYLOAD_SHORT] or [PAYLOAD_LONG].
   */