NIXL/EP/WHEEL: pack cu in diff namespace

[ofirfarjun7]

What?

Take only CUDA related from #1646

Summary by CodeRabbit

• New Features

  • Added intelligent CUDA-versioned backend selection for the nixl_ep Python package, automatically loading the matching CUDA backend and exposing its public APIs.

• Chores

  • Build and packaging updated to install Python package files under CUDA-versioned subdirectories and include the nixl_ep package in the published wheel.
  • Added mypy configuration tweaks for package-base handling and improved build-stage packaging of Python sources.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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📥 Commits

Reviewing files that changed from the base of the PR and between 94d25b7 and 97b53d2.

📒 Files selected for processing (1)

• src/bindings/python/nixl-meta/nixl_ep/__init__.py

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📝 Walkthrough

Walkthrough

Adds a nixl_ep meta-dispatcher that selects a CUDA-versioned backend at import time, updates builds to install EP extension and sources into CUDA-versioned subdirectories, and integrates nixl_ep into the nixl-meta wheel and mypy configuration.

Changes

CUDA-versioned nixl_ep Meta-dispatcher and Packaging

Layer / File(s)	Summary
nixl_ep meta-dispatcher module src/bindings/python/nixl-meta/nixl_ep/__init__.py, src/bindings/python/nixl-meta/nixl_ep/meson.build	Detects CUDA major version from torch.version.cuda, imports the matching nixl_ep_cu{major} backend (with fallback to nixl_ep_cu13/nixl_ep_cu12), registers buffer and utils submodules in sys.modules, attaches them to the nixl_ep namespace, and re-exports public symbols.
CUDA-versioned extension installation examples/device/ep/meson.build	Defines nixl_ep_install_dir as a CUDA-versioned subdirectory, sets the extension subdir to that dir, updates a custom copy target to mkdir/copy Python sources and the built extension into the CUDA-versioned path, and installs sources into the same subdir.
Meta-wheel packaging and build integration src/bindings/python/nixl-meta/meson.build, src/bindings/python/nixl-meta/nixl/meson.build, src/bindings/python/nixl-meta/nixl_ep/meson.build, src/bindings/python/nixl-meta/pyproject.toml.in	Adds nixl_ep traversal to the meta-wheel build, changes meta-wheel inputs to use generated build-dir copies for init/API/logging and nixl_ep init, assigns fs.copyfile results to variables for reuse, and adds nixl_ep to tool.setuptools.packages.
Type checking configuration pyproject.toml	Adds explicit_package_bases = true under [tool.mypy] to influence mypy package-base detection for the meta-dispatcher and EP sources.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

A rabbit hums by torchlight bright,
choosing cu paths in silent night,
packages hop to versioned homes,
extensions nest where CUDA roams,
a tiny stamp marks where it roamed. 🐇

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The PR description is incomplete; it only provides 'What?' but omits the required 'Why?' and 'How?' sections entirely.	Complete the description by adding a 'Why?' section explaining the motivation/justification and optionally a 'How?' section detailing the design approach for complex implementation details.
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'NIXL/EP/WHEEL: pack cu in diff namespace' accurately summarizes the main change: organizing CUDA-related wheels into separate namespaces based on CUDA versions.
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.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 2

🤖 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 `@src/bindings/python/nixl-meta/nixl_ep/__init__.py`:
- Around line 43-51: The loop in
src/bindings/python/nixl-meta/nixl_ep/__init__.py currently only continues
probing on ModuleNotFoundError, so ImportError/OSError from a failed extension
load blocks trying the next backend; change the try/except in the for mod_name
loop around importlib.import_module(mod_name) to handle ModuleNotFoundError
specially (re-raise if e.name != mod_name, otherwise continue) but also catch
ImportError and OSError and treat them as non-fatal (log/ignore and continue to
the next mod_name), ensuring the code will try "nixl_ep_cu12" if "nixl_ep_cu13"
fails to load at import time.
- Around line 56-73: The code is hoisting every non-underscore name from
submodules and the backend (_pkg) into the nixl_ep package, changing export
semantics; fix by mirroring the backend's declared exports instead of
indiscriminately copying all names: read export lists (use getattr(_pkg,
"__all__", None) and for each submodule use getattr(module, "__all__", None)),
build a single __all__ for nixl_ep from those declared export lists (fall back
to an explicit whitelist if neither provides __all__), and only setattr names
that appear in that computed __all__; update the loops that currently iterate
over dir(module) and dir(_pkg) to iterate over the chosen export lists and avoid
overwriting existing attributes on sys.modules[__name__].

🪄 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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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

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📥 Commits

Reviewing files that changed from the base of the PR and between 669eff6 and 94d25b7.

📒 Files selected for processing (7)

• examples/device/ep/meson.build
• pyproject.toml
• src/bindings/python/nixl-meta/meson.build
• src/bindings/python/nixl-meta/nixl/meson.build
• src/bindings/python/nixl-meta/nixl_ep/__init__.py
• src/bindings/python/nixl-meta/nixl_ep/meson.build
• src/bindings/python/nixl-meta/pyproject.toml.in

[ofirfarjun7]

/build

[ofirfarjun7]

/build