drop-stream

Do you need to know when your stream is dropped, after you pass it off?

DropStream will send a message to a futures::channel::oneshot::Reciever upon being dropped. You can run cleanup code and close connections when your stream's consumer drops it. This is especially useful when using frameworks that consume data streams.

Example

struct MyDataService {
  db_ref: Arc<SqlDatabase> //Example database type here
}

impl MyDataService {
  async get_change_feed(&self, user_id: String) -> Pin<Box<dyn Stream<Item = User>>> {

    // I need to close this session when the consumer stops listening to my stream
    let session = self.db_ref.new_session(user_id).await;
    
    let data_stream = session.changes();
    
    // This new wrapped stream will send a message to `rx` when dropped
    let (wrapped_stream, rx) = DropStream::new(data_stream);
    
    // Since using futures::channel::oneshot::Reciever, I can `await` the message
    tokio::spawn(async move {
      let _ = rx.await; // No actual value is passed as the message. We only care that a send was intended
      log::debug!("Closing stream...");
      let _close_success = session.close().await;
    });
    
    // Now I know I will close the session when the consumer is done with this :)
    wrapped_stream.boxed()
    
  }
}