Avoid modifying actual cache while recording optimistic transactions. #5484
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This is potentially an observable breaking change for code that accesses the real cache during optimistic updates, rather than using the provided proxy object. Previously, the real InMemoryCache would also have its cache.data and cache.optimisticData properties temporarily updated to point to the new optimistic layer, so it would behave like the proxy cache for the duration of the transaction. Now, only the proxy object is updated, and the real cache is left untouched. If this change causes any problems, the most likely solution is to make sure optimistic update functions only access the provided proxy object, if they are expecting to read or write optimistic data. See the tests that were updated in this commit for examples of this correction. However, if the goal is to access non-optimistic data, using the real cache should now work more predictably than before, since the real cache is no longer modified during the transaction. As a side benefit, we no longer need the try-finally block in performTransaction, because the proxy object can simply be forgotten once the transaction is done, so we no longer have to worry about resetting any temporarily modified properties of the real cache.
benjamn
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Feb 21, 2020
This essentially undoes #5484, so that reactive variables (which have access to the InMemoryCache object but know nothing about proxy objects) can benefit from transactional broadcast batching when calling cache.broadcastWatches().
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This is potentially an observable breaking change for code that accesses the real (as opposed to optimistic) cache during optimistic updates, rather than using the provided
proxyobject.Previously, the real
InMemoryCachewould also have itscache.dataandcache.optimisticDataproperties temporarily updated to point to the new optimistic layer, so it would behave like theproxycache for the duration of the transaction. Now, only theproxyobject is updated, and the real cache is left untouched.If this change causes any problems, the most likely solution is to make sure optimistic update functions only access the provided
proxyobject, if they are expecting to read or write optimistic data. See the tests that were updated in this commit for examples of this correction.However, if the goal is to access non-optimistic data, using the real cache should now work more predictably than before, since the real cache is no longer modified during the transaction.
As a side benefit, we no longer need the
try-finallyblock inperformTransaction, because theproxyobject can simply be forgotten once the transaction is done, so we no longer have to worry about resetting any temporarily modified properties of the real cache.