Refetch should not happen if no active subscribers

[AlexanderArvidsson]

Fixes #1530

All logic that checks if there are active subscriptions in the code does a falsey check as well as a keys length check on the subscription sub state, except for the code that refetches valid queries.
Here is an example from the handleUnsubscribe function.
Here is another from invalidateTags.
This PR includes the same check to resolve this issue. See #1530 for more information.
Attempting a refetch for data that has no subscribers should remove it from the cache, similar to invalidateTags, because the data would become stale relative to other cache data which would be refetched on focus / reconnect.

[phryneas]

Ha, timing ^^

What I said in the other thread pretty much applies here - "not fetching" in that case is not really an option, as that would leave stale data in the cache. In this case, the data would need to be removed from the cache, like it is in the case of cache invalidation.
Could you please adjust the PR accordingly?

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[AlexanderArvidsson]

I will adjust the PR tomorrow with the fixes, as per our discussion in the issue.

[AlexanderArvidsson]

@phryneas I changed the logic now and wrote a test for it. I considered placing the logic in cleanup.test.tsx but since refetchValidQueries is only run when refetching on focus or reconnect, I added it in refetchBehaviors.test.tsx.

Is it necessary to also include the same test for reconnect? They run the same function, so if the other tests for reconnect passes, and my new test passes, then it should be guaranteed to pass on reconnect too.

[AlexanderArvidsson]

@phryneas That should be the last changes. If there is anything else you'd like me to include, I'll be glad to.

When we can we expect this to be published? The current logic (where the data is refetched) results in quite a high performance impact on both backend and frontend in our current project. I am sure however we could work around it for now by disabling refetching on our specific endpoints.

[phryneas]

I'l try tol take a look at it this evening or tomorrow.
Afaik, @markerikson wanted to do a patch release soon so we should be able to get this in.

[phryneas]

Looks good to me. Let's get this in.

[phryneas]

Released in https://github.com/reduxjs/redux-toolkit/releases/tag/v1.7.2