Recommended handling in ConcurrencyDictionary<string, Task<T>> when task fails

[passuied]

Hi @davidfowl,

Trying to get rid of Task.Result in our code and follow your approach in AsyncGuidance.md#concurrentdictionarygetoradd by storing the Task instead of the actual value.
In our tests, it causes issue when the task fails (e.g. HTTP Exception) but the task obviously still gets added to the cache...

Any recommendations here?

Thanks,
Patrick

[davidfowl]

@passuied Just saw this. This is a tricky one. If you want to remove the entry from the dictionary when it fails then you might need something like GetOrAddAsync (https://gist.github.com/davidfowl/3dac8f7b3d141ae87abf770d5781feed#file-concurrentdictionaryextensions-cs-L53).

[bartelink]

Another approach might be to wrap it like this: https://stackoverflow.com/a/33942013/11635
There's an evolution of that with expiration semantics too (there are some tests if one wanted to port it to C#)