Calls are executed in one of two ways:

 * **Synchronous:** your thread blocks until the response is readable.
 * **Asynchronous:** you enqueue the request on any thread, and get [called back](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-callback/) on another thread when the response is readable.

    return null
  }

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

  }

  @Override public void callStart(Call call) {
    printEvent("callStart");
  }

  @Override public void callEnd(Call call) {
    printEvent("callEnd");
  }

  @Override public void dnsStart(Call call, String domainName) {
    printEvent("dnsStart");
  }

  @Override public void dnsEnd(Call call, String domainName, List<InetAddress> inetAddressList) {
    printEvent("dnsEnd");

	}
	return ok, err
}

// RLock calls read lock REST API.
func (c *lockRESTClient) RLock(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
	return c.call(ctx, lockRPCRLock, &args)
}

// Lock calls lock REST API.
func (c *lockRESTClient) Lock(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
	return c.call(ctx, lockRPCLock, &args)
}

// RUnlock calls read unlock REST API.

	globalServiceFreezeMu.Lock()
	// If multiple calls, first one creates channel.
	globalServiceFreezeCnt++
	if globalServiceFreezeCnt == 1 {
		globalServiceFreeze.Store(make(chan struct{}))
	}
	globalServiceFreezeMu.Unlock()
}

// unfreezeServices will unfreeze all incoming S3 API calls.
// For each call, unfreezeServices must be called once.
func unfreezeServices() {

@ElementTypesAreNonnullByDefault
@GwtCompatible(emulated = true)
public class SuppliersTest extends TestCase {

  static class CountingSupplier implements Supplier<Integer> {
    int calls = 0;

    @Override
    public Integer get() {
      calls++;
      return calls * 10;
    }

    @Override
    public String toString() {
      return "CountingSupplier";
    }
  }

@ElementTypesAreNonnullByDefault
@GwtCompatible(emulated = true)
public class SuppliersTest extends TestCase {

  static class CountingSupplier implements Supplier<Integer> {
    int calls = 0;

    @Override
    public Integer get() {
      calls++;
      return calls * 10;
    }

    @Override
    public String toString() {
      return "CountingSupplier";
    }
  }

    return copy(writeTimeoutMillis = checkDuration("writeTimeout", timeout.toLong(), unit))
  }

  override fun call(): Call = call

  override fun request(): Request = request

  @Throws(IOException::class)
  override fun proceed(request: Request): Response {
    check(index < interceptors.size)

    calls++

    if (exchange != null) {
      check(exchange.finder.routePlanner.sameHostAndPort(request.url)) {

    }
    return result
  }

  /**
   * Remove this call from the connection's list of allocations. Returns a socket that the caller
   * should close.
   */
  internal fun releaseConnectionNoEvents(): Socket? {
    val connection = this.connection!!
    connection.lock.assertHeld()

    val calls = connection.calls
    val index = calls.indexOfFirst { it.get() == this@RealCall }
    check(index != -1)

   *
   * <p>The objects returned by consecutive calls to {@link #peek()} then {@link #next()} are
   * guaranteed to be equal to each other.
   */
  @CanIgnoreReturnValue
  @Override
  @ParametricNullness
  E next();

  /**
   * {@inheritDoc}
   *
   * <p>Implementations may or may not support removal when a call to {@link #peek()} has occurred
   * since the most recent call to {@link #next()}.
   *