[C++] Caching pre computed data based on FunctionOptions in the kernel state

[asfimport]

See discussion here:

#8621 (comment)

 

A kernel might need to pre-compute something based on the function options passed. Since the Kernel-FunctionOptions mapping is not 1-to-1, it does not make sense to store this in the function option object. 

Currently, match_substring calculates a prefix_table on each Exec call. In trim (#8621 we compute a vector on each Exec call. This should be done only once and cached in the kernel state instead.

 

Reporter: Maarten Breddels / @maartenbreddels

Related issues:

• [C++] Persist SetLookupState in between usages of IsIn when filtering dataset batches (relates to)
• [C++] Implement string space trimming kernels: trim, ltrim, and rtrim (is related to)
• [C++] Add LRU cache facility (depends upon)

_{Note: This issue was originally created as ARROW-10556. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Isn't this what the init function is for?

https://github.com/apache/arrow/blob/master/cpp/src/arrow/compute/kernels/scalar_set_lookup.cc#L160