Make make_scalar_function() result candidate for inlining, by removing the Arc
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`make_scalar_function` serves as a template to implement functions, abstracting away processing of scalar values. While it's recommended to implement `ScalarUDFImpl` directly, a few functions still use the `make_scalar_function` helper, perhaps because it reduces code verbosity. While `make_scalar_function` is a template function, it's not eligible for effective inlining because of the `Arc<Fn>` return type. This commit removes `Arc` and unlocks inlining. The change impact was verified manually using `cargo rustc -p datafusion-functions-nested -- --emit asm -C opt-level=2` and comparing the generated for `ArrayDistance::invoke` exemplary function that uses `make_scalar_function`. Only after the changes can `ArrayDistance::invoke` call the `array_distance_inner` directly. The change saves some small overhead on each invocation of a UDF, but doesn't improve per-row performance.
alamb
changed the title
Arc
comphead
approved these changes
Sep 16, 2024
I think there some more usages of this type |
findepi
deleted the
findepi/make-make-scalar-function-result-candidate-for-inlining-bcdb1f
branch
FWIW with |
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make_scalar_functionserves as a template to implement functions, abstracting away processing of scalar values. While it's recommended to implementScalarUDFImpldirectly, a few functions still use themake_scalar_functionhelper, perhaps because it reduces code verbosity.While
make_scalar_functionis a template function, it's not eligible for effective inlining because of theArc<Fn>return type.This commit removes
Arcand unlocks inlining. The change impact wasverified manually using
cargo rustc -p datafusion-functions-nested -- --emit asm -C opt-level=2and comparing the generated forArrayDistance::invokeexemplary function that usesmake_scalar_function. Only after the changes canArrayDistance::invokecall thearray_distance_innerdirectly.The change saves some small overhead on each invocation of a UDF, but doesn't improve per-row performance.