@Override
  protected void doEnqueue(Callback<V> callback) {
    class CallbackRunnable implements Runnable {
      @Override
      public void run() {
        try {
          callback.onSuccess(doExecute());
        } catch (IOException e) {
          // unwrap the exception
          if (e.getCause() instanceof SQLException) {
            callback.onError(e.getCause());
          } else {
            callback.onError(e);
          }
        } catch (Throwable t) {
          propagateIfFatal(t);
          callback.onError(t);
        }
      }
    }
    factory.executor.execute(new CallbackRunnable());
  }
Uncancelable call built with an executor
zipkin-storage/mysql-v1/src/main/java/zipkin2/storage/mysql/v1/DataSourceCall.java