Only cache IF conditional

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
35/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
python
Domain
api

Research direction

Start by tracing the st.cache_resource decorator and its existing cache behavior; the issue does not name specific implementation files or tests. Define how a cache_if callback should control storing the decorated function's return value, then add coverage for successful and None results.

Written by the indexing model from the issue text.

Description

feature:cache type:enhancement
Checklist
  • I have searched the existing issues for similar feature requests.
  • I added a descriptive title and summary to this issue.
Summary

It would be useful if there is more control over the st.cache_* decorators, such as only caching the the result based on a given condition.

Why?

I have a resource cache that loads a transformers deep learning model. This week, the HF services went down, which meant that the model could not be loaded and yielded None. So now the cache for that model has been set to None and subsequent users cannot run the app because the model is not defined.

How?

Perhaps by adding an argument cache_if, that is passed to the constructor which must be a function that returns a bool. If True, the cacher will cache, otherwise it will not. The argument that will be passed to the defined cache_if-function is the return value of the decorated function.


def model_downloaded(model) -> bool:
    if model is None:
        return False
    else:
        return True

@st.cache_resource(show_spinner=False, max_entries=6, cache_if=model_downloaded)
def get_model():
    model = model_download()
    return model
Additional Context

No response

Dominant language
Python
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