feat(bitmap): support DIFF, DIFF1, ANDOR, ONE for BITOP command

[nkroker]

Summary

• Implements Redis 8.2+ BITOP operations: DIFF, DIFF1, ANDOR, ONE
• DIFF: bits set in X but not in any Y key (X & ~Y1 & ~Y2 & ...)
• DIFF1: bits set in any Y key but not in X ((Y1 | Y2 | ...) & ~X)
• ANDOR: bits set in X and in at least one Y key (X & (Y1 | Y2 | ...))
• ONE: bits set in exactly one key across all inputs

Changes

• src/types/redis_bitmap.h — 4 new BitOpFlags enum values
• src/types/redis_bitmap.cc — byte-loop logic for new ops + excluded from 64-bit fast path
• src/commands/cmd_bit.cc — parse diff/diff1/andor/one op name strings
• tests/gocase/unit/type/bitmap/bitmap_test.go — 9 targeted tests + fuzzing for all 4 ops

Test plan

• Basic correctness tests for each op
• Multi-key scenarios
• Missing key treated as zero bytes
• Fuzzing across random bitmaps with simulated reference implementation
• All existing BITOP tests pass

Ai Tools Used

• Claude Opus 4.6

Closes #3132

[jihuayu]

Hi @nkroker. Thanks for your contribution. Please read our guidelines for AI-assisted code contributions: https://kvrocks.apache.org/community/contributing#guidelines-for-ai-assisted-contributions

If you used AI-assisted coding, please let me know which software and model you used. This will help us review the code more effectively.

[nkroker]

Hi @jihuayu, I have used the Claude Opus 4.6 to make changes to the codebase, but I have also reviewed and checked the code by performing a build locally. I'll mention this in the description as well.

[jihuayu]

1. DIFF, DIFF1, and ANDOR produce incorrect results when the first source key does not exist, which is inconsistent with Redis semantics.

BITFIELD y SET u8 #0 15
BITOP DIFF dest nosuch y
BITFIELD dest GET u8 #0

In this PR
BITOP return length 1
BITFIELD dest GET u8 #0 return 15

But in Redis：

BITOP return length 1
BITFIELD dest GET u8 #0 return 0

It is also in DIFF、DIFF1、ANDOR

2. DIFF, DIFF1, and ANDOR lack minimum source key validation and do not align with Redis semantics.

BITFIELD x SET u8 #0 170

BITOP DIFF dest x
BITFIELD dest GET u8 #0

it will throw error in redis.

PS: You can explicitly require your AI tools to follow Redis semantics when coding to avoid these types of issues.

[jihuayu]

Also, you need to format the code (use clang-format) to ensure the GitHub Actions pass.

[jihuayu]

Hi @nkroker , just checking in on this PR since it's been quiet for a bit. Are you still planning to work on this? Let me know if you run into any issues and feel free to ping me.

[nkroker]

Hi @nkroker , just checking in on this PR since it's been quiet for a bit. Are you still planning to work on this? Let me know if you run into any issues and feel free to ping me.

Yes I'll update it actually I'm travelling that's why it's been open from few days

[jihuayu]

Yes I'll update it actually I'm travelling that's why it's been open from few days

Wow, thanks for your reply. Hope you have a great trip!

[jihuayu]

It looks like there may have been an issue while updating the code. Do you need any help?

[nkroker]

Hey @jihuayu is this PR still required or should I close it?

[jihuayu]

Hi @nkroker. Welcome back—we need you. I’ll find some time to take a look at the code.

[Copilot]

Pull request overview

This PR extends Kvrocks’ bitmap implementation to support additional Redis 8.2+ BITOP operations (DIFF, DIFF1, ANDOR, ONE). It updates command parsing, implements the new byte-wise operation semantics in the bitmap type layer (excluding them from the existing 64-bit fast path), and adds Go unit tests (including fuzzing) to validate correctness and Redis-compatible missing-key behavior.

Changes:

• Add new bitmap operation flags (DIFF, DIFF1, ANDOR, ONE) and wire them into BITOP parsing.
• Implement the new ops in Bitmap::BitOp with correct handling of missing keys (including Redis semantics for missing first key).
• Add targeted unit tests plus fuzzing to validate multi-key and missing-key cases for all new operations.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/types/redis_bitmap.h	Adds new BitOpFlags values for the four new operations.
src/types/redis_bitmap.cc	Implements new BITOP semantics in the bitmap engine and gates the 64-bit fast path for these ops.
src/commands/cmd_bit.cc	Extends BITOP op-name parsing and validates minimum arity for DIFF/DIFF1/ANDOR.
tests/gocase/unit/type/bitmap/bitmap_test.go	Adds correctness tests and fuzz coverage for the new operations and missing-key semantics.

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