Handling Queued Events #94
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dhavalshreyas
requested review from
bencochran,
zach-klippenstein,
AquaGeek and
rjrjr
rjrjr
reviewed
Feb 24, 2021
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| case .queued: | ||
| fatalError("[\(WorkflowType.self)] Action sent to pipe while already in the `queueing` state.") | ||
| fatalError("[\(WorkflowType.self)] Action sent to pipe while in the `pending` state.") |
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I thought this PR was to eliminate this error?
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Yeah, this should not be possible, however the .pending state will continue to exist. fatal ensures we don't hit this spot.
rjrjr
approved these changes
Feb 24, 2021
AquaGeek
approved these changes
Feb 24, 2021
Yes, all green. |
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Queued Events
Queued Events are events sent to the
Sinksynchronously whileScreens are being updated. Wequeuethem up and are applied after theScreenupdate operation.Issues
Our existing implementation of
Queuedevents handling has a few issues:Workflownode can handle only one event, if another event is sent, wefatalErrorwith aAction sent to pipe while in the pending state.message.Workflownodes have events queued, only one of them will be handled, the rest are silently dropped.enablingand handlingEventPipeswhile handlingqueuedevents, the Workflow tree can get into an inconsistent state and sometimes leads to a crash.Solution
To solve this issue, in this PR, we are not queueing events in the
SubtreeManager, instead we schedule the event to be delivered to theEventPipeasynchronously. This fixes the issues outlined above.