[oleksandr-pavlyk]

Description

This PR is the first in the sequence of more focused chunks comprising #10898

It splits c2h headers into parts to prepare ground for use of cuda::buffer with checked allocators analogous to what is used by c2h::device_vector and c2h::host_vector.

closes #11337

Checklist

• New or existing tests cover these changes.
• The documentation is up to date with these changes.

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• c2h/include/c2h/detail/env.cuh

🚧 Files skipped from review as they are similar to previous changes (1)

• c2h/include/c2h/detail/env.cuh

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📝 Summary

Summary by CodeRabbit

• New Features

  • Added device-vector generators for custom and scalar values, cyclic sequences, uniform offsets, and key-segment initialization.
  • Added configurable checked CUDA memory handling with allocation limits and diagnostics.
  • Added cross-platform environment-variable support and NVTX tracing for tests.

• Refactor

  • Reorganized generator, seed, tracing, and checked-allocation utilities into focused headers.

• Breaking Changes

  • Generator and seed APIs were moved from their previous public headers to dedicated interfaces.

Walkthrough

The change splits C2H testing, memory, environment, and generator code into dedicated headers. Public generator APIs move to vector_generators.h, while shared types and declarations move to generator_common.h.

Changes

C2H header refactor

Layer / File(s)	Summary
Extract detail utilities c2h/include/c2h/detail/..., c2h/include/c2h/checked_allocator.cuh, c2h/include/c2h/catch2_test_helper.h	Environment lookup, checked-memory utilities, NVTX fixtures, and seed helpers move to detail headers. The allocator and Catch2 macros use the new implementations.
Split generator contracts and implementations c2h/include/c2h/generator_common.h, c2h/include/c2h/vector_generators.h, c2h/include/c2h/generators.h, c2h/include/c2h/detail/generators.cuh	Generator wrapper types and declarations move to generator_common.h. Device-vector generator APIs move to vector_generators.h. Existing includes are rewired, and the old declarations are removed from generators.h.

Assessment against linked issues

Objective	Addressed	Explanation
Move and split existing C2H declarations and implementation headers, including detail-only utilities [#11337]	✅
Avoid behavior changes while preparing the header split [#11337]	❓	The checked-memory implementation changes free-memory clamping and subtraction behavior in c2h/include/c2h/detail/checked_memory.cuh:43-63. The generator APIs and Catch2 seed helpers also move while their declarations are reorganized.

Out-of-scope changes

Code Change	Explanation
Changed free-memory clamping and subtraction behavior (c2h/include/c2h/detail/checked_memory.cuh)	The linked objective requests a header-only refactor with no behavior changes.
Added conditional CUDA type support and new vector generator implementation structure (c2h/include/c2h/vector_generators.h)	The linked objective explicitly excludes generator changes.

Suggested reviewers: bernhardmgruber, jacobfaib

Priority: ➖ Normal

Change: Refactor

Merge Risk: ⚪ Minimal · up to e733d

The header-only refactor has no identified merge-blocking risk.

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Actionable comments posted: 1

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Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

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Run ID: 366d9dd1-bf1e-474a-b763-f7d44039f8eb

📥 Commits

Reviewing files that changed from the base of the PR and between 2d7377c and 2e69367.

📒 Files selected for processing (10)

• c2h/include/c2h/catch2_test_helper.h
• c2h/include/c2h/checked_allocator.cuh
• c2h/include/c2h/detail/catch2_nvtx.h
• c2h/include/c2h/detail/catch2_seed.h
• c2h/include/c2h/detail/checked_memory.cuh
• c2h/include/c2h/detail/env.cuh
• c2h/include/c2h/detail/generators.cuh
• c2h/include/c2h/generator_types.h
• c2h/include/c2h/generators.h
• c2h/include/c2h/vector_generators.h

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