openresty / openresty/lua-nginx-module
Feature request: conditional shdict:set
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- Dominant language
- C
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Description
Hi,
could you please implement this function:
ret=shdict:set_conditional(key, new_value, old_value)
Interpretation: only set "key" to "new_value" if currently "key" contains "old_value". If "new_value" is set return true, otherwise false.
Without such a function, re-caching leads to many parallel re-cache attempts as the "expired-condition" is true for too many concurrent requests resulting in load-peaks. To only allow ONE update one needs such a conditional set.
Thank you!
Thomas
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by locating the shdict:set implementation and any related tests in lua-nginx-module. Review how shared-dictionary values are read and written, then define coverage for matching and non-matching old values. Done means shdict:set_conditional returns true only when the current value matches old_value and otherwise returns false without updating the key.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- c, lua, nginx
- Domain
- api, backend
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100