Make BlockTransposed cloneable by partychen · Pull Request #1267 · microsoft/DiskANN

partychen · 2026-07-21T08:11:42Z

Does this PR have a descriptive title that could go in our release notes?
Does this PR add any new dependencies?
Does this PR modify any existing APIs?
Is the change to the API backwards compatible?
Should this result in any changes to our documentation, either updating existing docs or adding new ones?

Reference Issues/PRs

What does this implement/fix? Briefly explain your changes.

This makes diskann_quantization::multi_vector::BlockTransposed implement Clone.

The block-transposed representation now implements NewCloned by copying its complete backing allocation, including row, column, and packing padding. This lets the existing Mat<T> clone machinery provide a deep clone without reconstructing the logical matrix or changing its physical layout.

A regression test verifies that the clone preserves the complete backing storage, owns a distinct allocation, and can be mutated without affecting the original.

Any other comments?

Validated with:

cargo test -p diskann-quantization
cargo clippy -p diskann-quantization --all-targets -- -D warnings

Implement cloning for the block-transposed representation by copying its complete backing allocation, including padding, and verify cloned matrices own independent storage. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: e50cc67e-4fa3-4f9c-ac82-89c85f4182f3

Copilot

Pull request overview

Adds Clone support for diskann_quantization::multi_vector::BlockTransposed by teaching the underlying BlockTransposedRepr how to deep-clone its entire backing allocation (including padding), enabling Mat<T>’s existing Clone machinery to produce a layout-preserving clone.

Changes:

Implement NewCloned for BlockTransposedRepr by copying storage_len() elements from the raw backing allocation into a new owned Mat.
Derive Clone for BlockTransposed, making the owned wrapper cloneable.
Add a regression test intended to validate allocation independence and clone correctness.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Write sentinels into column padding, remainder-row padding, and their intersection before cloning so the regression test distinguishes a full backing-allocation copy from logical reconstruction. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: e50cc67e-4fa3-4f9c-ac82-89c85f4182f3

Copilot

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

codecov-commenter · 2026-07-21T08:49:30Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.48%. Comparing base (bacc7ef) to head (f18874e).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1267      +/-   ##
==========================================
- Coverage   91.06%   90.48%   -0.59%     
==========================================
  Files         500      498       -2     
  Lines       95938    95550     -388     
==========================================
- Hits        87369    86455     -914     
- Misses       8569     9095     +526

Flag	Coverage Δ
miri	`90.48% <100.00%> (-0.59%)`	⬇️
unittests	`90.14% <100.00%> (-0.89%)`	⬇️

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

Files with missing lines	Coverage Δ
...-quantization/src/multi_vector/block_transposed.rs	`96.96% <100.00%> (+0.08%)`	⬆️

... and 44 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

hildebrandmw · 2026-07-22T19:29:19Z

+        let repr = *v.repr();
+        // SAFETY: `v` points to an allocation described by `repr`, which contains
+        // exactly `storage_len` initialized elements.
+        let data =


This is probably slightly more efficient as it doesn't have to go through Vec, which potentially over-allocates.

let b: Box<[_]> = unsafe { std::slice::from_raw_parts(...) }.into();

Agreed, let's avoid the indirection through Vec here since this is potentially a large-ish allocation.

Thanks for your review. Fixed as suggestion.

hildebrandmw · 2026-07-22T19:30:15Z

+        // SAFETY: `v` points to an allocation described by `repr`, which contains
+        // exactly `storage_len` initialized elements.
+        let data =
+            unsafe { std::slice::from_raw_parts(v.as_raw_ptr().cast::<T>(), repr.storage_len()) };


You can probably do BlockTransposeRef::new(v).as_slice() to avoid the unsafe here. Or rather, we could if such a constructor existed ... which is probably needs to.

Thanks for your review. Fixed as suggestion.

Clone through BlockTransposedRef's safe slice API and convert the slice directly into a precisely sized Box allocation, avoiding both local unsafe code and Vec over-allocation. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: e50cc67e-4fa3-4f9c-ac82-89c85f4182f3

Copilot

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: e50cc67e-4fa3-4f9c-ac82-89c85f4182f3

Copilot

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

partychen · 2026-07-23T03:29:53Z

@hildebrandmw and @arkrishn94,could you please help to review the pr again? Thank you!

partychen requested review from a team and Copilot July 21, 2026 08:11

Copilot started reviewing on behalf of partychen July 21, 2026 08:12 View session

Copilot AI reviewed Jul 21, 2026

View reviewed changes

Comment thread diskann-quantization/src/multi_vector/block_transposed.rs

Copilot AI review requested due to automatic review settings July 21, 2026 08:34

Copilot started reviewing on behalf of partychen July 21, 2026 08:34 View session

Copilot AI reviewed Jul 21, 2026

View reviewed changes

hildebrandmw reviewed Jul 22, 2026

View reviewed changes

Copilot AI review requested due to automatic review settings July 23, 2026 02:04

Copilot started reviewing on behalf of partychen July 23, 2026 02:04 View session

Copilot AI reviewed Jul 23, 2026

View reviewed changes

Inline repr binding in new_cloned

f18874e

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: e50cc67e-4fa3-4f9c-ac82-89c85f4182f3

Copilot AI review requested due to automatic review settings July 23, 2026 02:10

Copilot started reviewing on behalf of partychen July 23, 2026 02:11 View session

Copilot AI reviewed Jul 23, 2026

View reviewed changes

Uh oh!

Conversation

partychen commented Jul 21, 2026

Reference Issues/PRs

What does this implement/fix? Briefly explain your changes.

Any other comments?

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

codecov-commenter commented Jul 21, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Codecov Report

Uh oh!

hildebrandmw Jul 22, 2026

Choose a reason for hiding this comment

Uh oh!

arkrishn94 Jul 22, 2026

Choose a reason for hiding this comment

Uh oh!

partychen Jul 23, 2026

Choose a reason for hiding this comment

Uh oh!

hildebrandmw Jul 22, 2026

Choose a reason for hiding this comment

Uh oh!

arkrishn94 Jul 22, 2026

Choose a reason for hiding this comment

Uh oh!

partychen Jul 23, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

partychen commented Jul 23, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

codecov-commenter commented Jul 21, 2026 •

edited

Loading