[WIP] Add filtering support for IVF-PQ and BITMAP filtering for CAGRA

[jeremywgleeson]

Summary

This PR adds filter support to the IVF-PQ C API (which previously had no filtering capability) and adds BITMAP filter support to the CAGRA and IVF-Flat C API (which only supported BITSET filters). Additionally, it adds strong filter support to the Rust crate, which was previously not exposed.

Changes

1. IVF-PQ C API - Add Filter Support

   • Add cuvsFilter filter parameter to cuvsIvfPqSearch
   • Implement BITMAP (per-query) and BITSET (global) filter support
   • IVF-PQ previously had no filtering capability in the C API

2. IVF-Flat C API - Add BITMAP Filter Support

   • Add BITMAP filter support to cuvsIvfFlatSearch
   • IVF-Flat previously only supported BITSET filters, now supports both
   • Matches full filtering functionality available in the C++ API

3. CAGRA C API - Add BITMAP Filter Support

   • Add BITMAP filter support to cuvsCagraSearch
   • CAGRA previously only supported BITSET filters, now supports both
   • Matches full filtering functionality available in the C++ API

4. Comprehensive Test Coverage

   • Add filtered search tests for IVF-PQ (ann_ivf_pq_c.cu)
   • Add filtered search tests for IVF-Flat (ann_ivf_flat_c.cu)
   • Add filtered search tests for CAGRA (ann_cagra_c.cu)
   • Each test suite includes both BITSET and BITMAP filter validation
   • Tests verify that filtered results respect the exclusion criteria

5. Rust Language Bindings - Complete Filter Support

   • Add new filters.rs module with comprehensive filter utilities
   • BITSET Helpers:
     • bitset_from_excluded_indices() - Create global filter from excluded indices
     • bitset_from_included_indices() - Create global filter from included indices
   • BITMAP Helpers:
     • bitmap_from_excluded_indices() - Create per-query filters from excluded indices
     • bitmap_from_included_indices() - Create per-query filters from included indices
   • All functions follow idiomatic Rust patterns with proper error handling
   • Memory-safe wrappers around DLPack tensors for filter data
   • Comprehensive documentation and examples for each function

6. Other Language Bindings

   • Update Python bindings to accept optional filter parameter
   • Update Go bindings to pass NO_FILTER by default

Backward Compatibility

C API - Breaking Changes:

• ⚠️ BREAKING: cuvsIvfPqSearch now requires an additional trailing cuvsFilter filter parameter
• Existing C code calling IVF-PQ search must be updated to pass a filter parameter (use {.type = NO_FILTER, .addr = (uintptr_t)NULL} for no filtering)
• Note: IVF-Flat and CAGRA already had the filter parameter, so no breaking changes for those

(Based on #664 , it seems that this type of change is not considered breaking?)

Rust API - Breaking Changes:

• ⚠️ BREAKING: Search function signatures updated to include filter parameter
• Existing Rust code must be updated to pass a filter (use appropriate helper functions from new filters module or None)

Python API - Non-Breaking:

• Filter parameter is optional with default value filter=None
• Filter placed after resources parameter to maintain backward compatibility for positional arguments
• Existing Python code continues to work unchanged

Go API - Non-Breaking:

• Filter automatically initialized to NO_FILTER internally
• Existing Go code continues to work unchanged

Testing

All new functionality is covered by unit tests that:

• Create random datasets and queries
• Apply filters to exclude even-indexed vectors (pattern: 0xAAAAAAAA)
• Verify all returned neighbors are odd-indexed
• Test both BITMAP and BITSET filter modes for each index type

Closes #1464

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[cjnolet]

/ok to test 6ee63bf

[cjnolet]

Thanks so much for the contribution @jeremywgleeson! This is a few important features that we've had on our roadmap and we really appreciate your help here.

[cjnolet]

/ok to test 577d5de

[benfred]

/ok to test 760b3d1

[benfred]

/ok to test e6feca5