public static RequestQueue getRequestQueue(Context context) {
    if (sRequestQueue == null) {
      File cacheDir = new File(context.getCacheDir(), VOLLEY_CACHE_DIR);
      sRequestQueue =
          new RequestQueue(
              new DiskBasedCache(cacheDir, ConfigConstants.MAX_DISK_CACHE_SIZE),
              new BasicNetwork(new HurlStack()));
      sRequestQueue.start();
    }
    return sRequestQueue;
  }
Creates singletons of relevant volley classes
samples/comparison/src/main/java/com/facebook/samples/comparison/configs/volley/SampleVolleyFactory.java