[Access] Properly handle subscription errors in data providers #7046
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Distinguish between `context.Canceled` errors originating from the streamer and those triggered by the DataProvider’s `Close()` method. Use `wasClosedByClient()` to suppress expected cancellations while propagating unexpected ones
illia-malachyn
requested review from
UlyanaAndrukhiv,
AndriiDiachuk,
Guitarheroua and
peterargue
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Additional details and impacted files@@ Coverage Diff @@
## master #7046 +/- ##
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- Coverage 41.23% 41.19% -0.04%
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Files 2138 2149 +11
Lines 188585 189056 +471
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+ Hits 77764 77884 +120
- Misses 104327 104666 +339
- Partials 6494 6506 +12
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After discussing with Yurii, we agreed to use a different approach here. |
illia-malachyn
changed the title
Guitarheroua
dismissed
their stale review
As this will changed, will re-aprove final implementation
We use it to distinguish place where cxt.Canceled error comes from. Also, I refactored each data provider's Run() function. Now it's more readable and clear.
illia-malachyn
changed the title
Hey. I updated PR's description. Added a context of what has been done and why. |
engine/access/rest/websockets/data_providers/account_statuses_provider.go
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| } | ||
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| var accountStatusesPayload models.AccountStatusesResponse | ||
| defer messageIndex.Increment() |
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all places with messageIndex increment were refactored
| @@ -15,6 +17,9 @@ type baseDataProvider struct { | |||
| cancel context.CancelFunc | |||
| send chan<- interface{} | |||
| subscription subscription.Subscription | |||
| // Ensures the closedChan has been closed once. | |||
| closedFlag sync.Once | |||
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Added closedChan channel
| ) error { | ||
| for { | ||
| select { | ||
| case <-closedChan: |
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run() is aware of closedChan and returns nil if it was closed
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@peterargue I also pointed out the most important lines of code |
Distinguish between
context.Cancelederrors originating from the streamer and those triggered by the DataProvider’sClose()method.closeChanthat is used inDataProvider.Close()method to indicateDataProvider.Run()that users of data providers (WebSocket controller in our case) want to finish receiving data.HandleSubscription()function is replaced byrun()function that is aware ofcloseChan. I made a new function for it becauseHandleSubscription()is widely used in the access package (HandleRPCSubscriptionhas 22 usages atm).run()returns nil ifcloseChanwas closed.HandleSubscriptionreturnedctx.Canceledwhich lead to confusion asctx.Canceledcould come from 2 sources (streamer and websocket controller).sendResponse()functions to make it more readable.Closes #7040 #7047