in src/filtered_log_processor.rs [68:77]
fn force_flush(&self) -> LogResult<()> {
let (res_sender, res_receiver) = oneshot::channel();
self.message_sender
.try_send(BatchMessage::Flush(Some(res_sender)))
.map_err(|err| LogError::Other(err.into()))?;
futures_executor::block_on(res_receiver)
.map_err(|err| LogError::Other(err.into()))
.and_then(std::convert::identity)
}