Bloc: Must wait for first Event done before start second Event

[anticafe]

Describe the bug
I cannot start 2 Events simultaneously. Must wait for first Event done before start second Event.

To Reproduce
Steps to reproduce the behavior:

1. Create a sample to download file. I dispatch EventDownloadStart to the DownloadBloc in order to start downloading. Then in main UI, I receive StateDownloadProgress(double progress).
2. Touch on button Stop downloading to dispatch EventDownloadStop.
3. Watch to log and realize there is no log of EventDownloadStop yet but download is still in progress. Until download is done then I see the log of EventDownloadStop.

Expected behavior
It seems Bloc must wait for first Event done before can be able to process next Event. But I hope Bloc can also process second event simultaneously.

Additional context
Here is the sample app: https://drive.google.com/open?id=1WiUxT_danFVBSLwZmdxQha_mAEDKtxAU

[felangel]

Hey @anticafe 👋

Thanks for reporting this and linking to the example app! I’ll take a look later today 👍

[felangel]

Hi @anticafe,

I was able to achieve the desired functionality by modifying the download_bloc to maintain a StreamSubscription for the download progress instead of using await and blocking the mapEventToState loop.

If you update your bloc and flutter_bloc versions

bloc: ^0.12.0
flutter_bloc: ^0.11.0

then you can copy this version of download_bloc.dart into your application and it should work as expected.

You can also check out the flutter_bloc_with_stream example app for a simplified version.

In general, if you await on a stream in mapEventToState then you are blocking the event loop until the stream is closed.

Hope that helps and great question! 💯