Move ObjectPool from diskann to diskann-utils

[arkrishn94]

Relocates the object pool module so that it is available to crates that depend on diskann-utils but not diskann.

Warning: This a public API breaking change.

Motivation

Implement pool-aware distance-table allocation for PQ in diskann-quantization .

Direct importers in diskann-providers, diskann-disk, and diskann-garnet are switched to use diskann_utils::object_pool directly.

[Copilot]

Pull request overview

Relocates the ObjectPool implementation from diskann into diskann-utils so pooling utilities can be used by crates that depend on diskann-utils without pulling in diskann (e.g., upcoming quantization work).

Changes:

• Removed diskann::utils::object_pool module and updated diskann call sites to import pooling types from diskann_utils::object_pool.
• Added diskann-utils::object_pool module (including tests) and exported it from diskann-utils’s lib.rs.
• Updated direct importers in diskann-providers, diskann-disk, and diskann-garnet to use diskann_utils::object_pool.

Reviewed changes

Copilot reviewed 13 out of 14 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
diskann/src/utils/mod.rs	Stops exposing object_pool from diskann::utils (public API surface change).
diskann/src/graph/search/scratch.rs	Switches AsPooled import to diskann_utils::object_pool.
diskann/src/graph/index.rs	Switches ObjectPool/PooledRef import to diskann_utils::object_pool.
diskann-utils/src/object_pool.rs	New pooled-object implementation + tests moved into diskann-utils.
diskann-utils/src/lib.rs	Exposes the new object_pool module publicly.
diskann-providers/src/model/pq/distance/{common,dynamic,innerproduct,l2}.rs	Updates pooling imports to diskann_utils.
diskann-providers/src/model/graph/provider/async_/{memory_quant_vector_provider,fast_memory_quant_vector_provider,bf_tree/quant_vector_provider}.rs	Updates ObjectPool import to diskann_utils.
diskann-garnet/src/provider.rs	Updates pooling imports to diskann_utils.
diskann-disk/src/search/provider/disk_provider.rs	Updates pooling imports to diskann_utils.

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.42%. Comparing base (3a20042) to head (316e21f).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #975      +/-   ##
==========================================
- Coverage   89.43%   89.42%   -0.01%     
==========================================
  Files         449      449              
  Lines       83779    83779              
==========================================
- Hits        74926    74923       -3     
- Misses       8853     8856       +3     

Flag	Coverage Δ
miri	89.42% <ø> (-0.01%)	⬇️
unittests	89.27% <ø> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
diskann-disk/src/search/provider/disk_provider.rs	90.89% <ø> (ø)
diskann-garnet/src/provider.rs	83.36% <ø> (ø)
...ovider/async_/fast_memory_quant_vector_provider.rs	98.46% <ø> (ø)
...ph/provider/async_/memory_quant_vector_provider.rs	98.36% <ø> (ø)
diskann-providers/src/model/pq/distance/common.rs	100.00% <ø> (ø)
diskann-providers/src/model/pq/distance/dynamic.rs	86.91% <ø> (ø)
...nn-providers/src/model/pq/distance/innerproduct.rs	100.00% <ø> (ø)
diskann-providers/src/model/pq/distance/l2.rs	100.00% <ø> (ø)
diskann-utils/src/lib.rs	100.00% <ø> (ø)
diskann-utils/src/object_pool.rs	97.38% <ø> (ø)
... and 2 more

... and 1 file with indirect coverage changes

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