feat: add onlyUpdateCache option

[tw7613781]

provide an option to only update cache no matter cache be hit or missed to meet some business logic requirements.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (83df4de) 62.67% compared to head (b6d3788) 64.70%.
Report is 6 commits behind head on main.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main      #38      +/-   ##
==========================================
+ Coverage   62.67%   64.70%   +2.02%     
==========================================
  Files           5        5              
  Lines         284      289       +5     
==========================================
+ Hits          178      187       +9     
+ Misses         93       90       -3     
+ Partials       13       12       -1     

Flag	Coverage Δ
unittests	64.70% <100.00%> (+2.02%)	⬆️

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[chenyahui]

In your scenario, is the response not required in any case (regardless of requesting the backend or not)? Only used to refresh cache?

[tw7613781]

Thank you for prompt reply.
The response is required, it should be the latest result of requesting the backend service.

The full scenario is as follow:
the http service will have 2 endpoints.

• one endpoint cache the result (for eg: /cache/dataset?uid=1)
• one endpoint return the latest result from backend and refresh the cache of the above endpoint (for eg: /dataset?uid=1, it will refresh the cache of /cache/dataset?uid=1)

the code is as below

r.GET("/cache/dataset", cache.CacheByRequestURI(memoryStore, time.Hour*2, cache.IgnoreQueryOrder()), handlerFunc)
r.GET("/dataset", cache.CacheByRequestURI(memoryStore, time.Hour*2, cache.OnlyUpdateCache(), cache.IgnoreQueryOrder(), cache.WithPrefixKey("/cache")), handlerFunc)

[chenyahui]

I probably understand. Let me think about this scenario first and see if there is a more suitable solution.