Prepare librtcx for standalone usage

[vyasr]

Description

This PR makes a number of changes to rtcx's CMake to support using an out-of-tree version of it.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

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📥 Commits

Reviewing files that changed from the base of the PR and between 1972d88 and 8a14ff1.

📒 Files selected for processing (15)

• python/cudf_streaming/cudf_streaming/examples/ray_shuffle_example.py
• python/cudf_streaming/cudf_streaming/testing.py
• python/cudf_streaming/cudf_streaming/tests/test_allgather.py
• python/cudf_streaming/cudf_streaming/tests/test_bloom_filter.py
• python/cudf_streaming/cudf_streaming/tests/test_integration_partition.py
• python/cudf_streaming/cudf_streaming/tests/test_partition.py
• python/cudf_streaming/cudf_streaming/tests/test_shuffler.py
• python/cudf_streaming/cudf_streaming/tests/test_sparse_alltoall.py
• python/cudf_streaming/cudf_streaming/tests/test_streaming_allgather.py
• python/cudf_streaming/cudf_streaming/tests/test_streaming_define_actor.py
• python/cudf_streaming/cudf_streaming/tests/test_streaming_fanout.py
• python/cudf_streaming/cudf_streaming/tests/test_streaming_leaf_actor.py
• python/cudf_streaming/cudf_streaming/tests/test_streaming_shuffler.py
• python/cudf_streaming/cudf_streaming/tests/test_streaming_sparse_alltoall.py
• python/cudf_streaming/cudf_streaming/tests/test_table_chunk.py

✅ Files skipped from review due to trivial changes (4)

• python/cudf_streaming/cudf_streaming/tests/test_table_chunk.py
• python/cudf_streaming/cudf_streaming/tests/test_streaming_sparse_alltoall.py
• python/cudf_streaming/cudf_streaming/tests/test_shuffler.py
• python/cudf_streaming/cudf_streaming/examples/ray_shuffle_example.py

---

📝 Walkthrough

Summary by CodeRabbit

• Chores

  • Improved build/install integration with a configurable install option and package export so consumers can find the library from build or install locations.
  • Centralized version/branch references for more consistent configuration loading.

• Bug Fixes

  • Embedding no longer fails when optional compression is disabled; compression-related include/link checks now run only when enabled.

• New Features

  • Added a shared test assertion utility and updated tests to import and use it.

Walkthrough

Integrates RAPIDS CMake packaging into librtcx: local VERSION/RAPIDS_BRANCH resolution, switch to rapids_find_package for CUDA tied to an export set, add conditional install/export registration for rtcx, defer zstd validation into embed(), and add a local cudf_streaming.testing.assert_eq used by tests.

Changes

librtcx RAPIDS packaging

Layer / File(s)	Summary
Version and RAPIDS configuration cpp/librtcx/VERSION, cpp/librtcx/RAPIDS_BRANCH, cpp/librtcx/cmake/rapids_config.cmake	Adds local VERSION and RAPIDS_BRANCH references and updates rapids_config.cmake to read them from cpp/librtcx/cmake/.. instead of the repository root.
RAPIDS CMake integration and dependency management cpp/librtcx/CMakeLists.txt	Includes RAPIDS CMake modules and replaces find_package(CUDAToolkit REQUIRED) with rapids_find_package(... BUILD_EXPORT_SET rtcx-exports INSTALL_EXPORT_SET rtcx-exports).
Install and export configuration cpp/librtcx/CMakeLists.txt	Adds GNUInstallDirs, RTCX_INSTALL option, consumer configure-time code strings, conditional install of rtcx target/headers/embed assets, and registers install-time and unconditional build-tree exports via rapids_export.
Lazy zstd requirement validation cpp/librtcx/embed.cmake	Removes top-level zstd check; embed() now links ${CMAKE_DL_LIBS} always and only requires zstd (with fatal error) when COMPRESSION is not none.
cudf_streaming testing helper and imports python/cudf_streaming/cudf_streaming/testing.py, python/cudf_streaming/cudf_streaming/examples/*, python/cudf_streaming/cudf_streaming/tests/*	Adds assert_eq utility and switches tests/examples to import it from cudf_streaming.testing instead of rapidsmpf.testing; some import reordering.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• rapidsai/cudf#22744: Modifies the same librtcx CMake packaging layer and embed.cmake validation.
• rapidsai/cudf#22760: Adds cudf_streaming.testing.assert_eq and updates tests to use it.

Suggested labels

improvement

Suggested reviewers

• lamarrr
• davidwendt
• bdice
• igorpeshansky

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'Prepare librtcx for standalone usage' accurately summarizes the main change: updating rtcx's CMake configuration to support out-of-tree usage.
Description check	✅ Passed	The description is related to the changeset, explaining that the PR makes changes to rtcx's CMake to support out-of-tree usage and noting test coverage and documentation updates.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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---

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@cpp/librtcx/embed.cmake`:
- Around line 271-279: The embed() logic currently always requires and links
zstd (target_include_directories/target_link_libraries and the NOT TARGET zstd
check), which breaks when COMPRESSION is set to "none"; update the CMake snippet
to only perform the zstd include/check/link when the COMPRESSION variable is not
"none" (i.e., wrap the zstd-related target_include_directories, the NOT TARGET
zstd FATAL_ERROR check, and the target_link_libraries(... zstd) call in a
conditional that checks COMPRESSION != "none" while leaving
set_target_properties(${RUNNER} ...) unchanged; reference RUNNER and the zstd
target in the conditional).

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

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📥 Commits

Reviewing files that changed from the base of the PR and between b5588b6 and 9e2c29e.

📒 Files selected for processing (5)

• cpp/librtcx/CMakeLists.txt
• cpp/librtcx/RAPIDS_BRANCH
• cpp/librtcx/VERSION
• cpp/librtcx/cmake/rapids_config.cmake
• cpp/librtcx/embed.cmake

[KyleFromNVIDIA]

Is this a symlink? This and VERSION should be symlinks.

[vyasr]

I can change it for now, but it'll wind up getting copied as soon as we split this out into its own repo anyway.

[bdice]

All looks fine aside from the symlink question.

[vyasr]

rapidsai/rapidsmpf#1094 removed the rapidsmpf.testing.assert_eq utility, which it turns out cudf_streaming tests were still relying on. That was an oversight as part of the transition. Aside from that, CI was passing on this previous run on 1972d88. Normally I would make a separate PR to fix this kind of issue, and the fix I pushed here requires a review from rapidsmpf-python-codeowners, but cudf CI has been blocked enough lately and the change I made to get the cudf_streaming tests passing is pretty noncontroversial (just copying in a test helper), so I will admin-merge as soon as CI passes to get things unblocked.