private var writer = Http2Writer(bytesOut, client)
  private val outFrames: MutableList<OutFrame> = ArrayList()
  private val inFrames: BlockingQueue<InFrame> = LinkedBlockingQueue()
  private var port = 0
  private val executor = Executors.newSingleThreadExecutor(threadFactory("MockHttp2Peer"))
  private var serverSocket: ServerSocket? = null
  private var socket: Socket? = null

  fun setClient(client: Boolean) {
    if (this.client == client) return

      get() = originalRequest

    val call: RealCall
      get() = this@RealCall

    /**
     * Attempt to enqueue this async call on [executorService]. This will attempt to clean up
     * if the executor has been shut down by reporting the call as failed.
     */
    fun executeOn(executorService: ExecutorService) {
      client.dispatcher.assertThreadDoesntHoldLock()

      var success = false
      try {

      .build()

  @After
  fun tearDown() {
    engine.shutdown()
    cacheDir.deleteRecursively()
  }

  @Test
  fun get() {
    val executor = Executors.newCachedThreadPool()

    val completableFuture = execute(engine, executor, "https://google.com/robots.txt")

    try {
      val response = completableFuture.get(10, TimeUnit.SECONDS)

      assertEquals(200, response.code)

class RelayTest {
  @TempDir
  var tempDir: File? = null
  private val executor = Executors.newCachedThreadPool(threadFactory("RelayTest"))
  private val metadata: ByteString = "great metadata!".encodeUtf8()
  private lateinit var file: File

  @BeforeEach
  fun setUp() {
    file = File(tempDir, "test")
  }

  @AfterEach
  fun tearDown() {
    executor.shutdown()
  }

  @Test
  fun singleSource() {

    dispatcher.maxRequestsPerHost = 4
    executor.assertJobs("http://a/1", "http://a/2", "http://a/3", "http://a/4")
  }

  @Test
  fun oldJobFinishesNewJobCanRunDifferentHost() {
    dispatcher.maxRequests = 1
    client.newCall(newRequest("http://a/1")).enqueue(callback)
    client.newCall(newRequest("http://b/1")).enqueue(callback)
    executor.finishJob("http://a/1")
    executor.assertJobs("http://b/1")
  }

  @Test

    )
  }

  fun connectionCount(): Int = connectionCount.get()

  fun shutdown() {
    serverSocket!!.close()
    executor.shutdown()
    if (!executor.awaitTermination(5, TimeUnit.SECONDS)) {
      throw IOException("Gave up waiting for executor to shut down")
    }
  }

  private fun service(from: Socket) {
    val name = "SocksProxy ${from.remoteSocketAddress}"
    threadName(name) {

  }

  private void parallelDrainQueue(int threadCount) {
    ExecutorService executor = Executors.newFixedThreadPool(threadCount);
    for (int i = 0; i < threadCount; i++) {
      executor.execute(() -> {
        try {
          drainQueue();
        } catch (Exception e) {
          e.printStackTrace();
        }
      });
    }
    executor.shutdown();
  }

  private void drainQueue() throws Exception {

    val flags: Int,
    val callback: DnsResolver.Callback<List<InetAddress>>,
  )

  @Implementation
  fun query(
    network: Network?,
    domain: String,
    nsType: Int,
    flags: Int,
    executor: Executor,
    cancellationSignal: CancellationSignal?,
    callback: DnsResolver.Callback<List<InetAddress>>,
  ) {
    responder(Request(network, domain, nsType, flags, callback))
  }

  companion object {

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

We have 3 different things that we synchronize on.

#### Http2Connection

package okhttp3.recipes;

import java.io.IOException;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import okhttp3.Call;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class CancelCall {
  private final ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);