rapidsai/cudf

[FEA] Implement Java/JNI function `applyNullMask`

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#16,764 opened on Sep 6, 2024

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feature requestgood first issue

Description

We need a function in Java/JNI to apply a null mask onto some provided input column. This functionality is used a lot in Spark-rapids plugin.

Currently, we can achieve this using copy_if_else but we have to create and provide a null scalar for the else (if not valid) option, which is a bit inconvenient and incurs additional maintenance overhead.

Contributor guide

Tech stack
javacpp
Domain
backenddata
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
JavaC++JNIcuDF codebase
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Investigate existing JNI functions in the cudf Java bindings to understand the pattern. Look at the current use of copy if else to see how null mask is applied. Propose a new JNI function that applies null mask directly, possibly by modifying existing code. Discuss with maintainers on the issue thread for any design preferences.