Make queue.closest_notvisited() safe and update call sites#787
Merged
Conversation
Contributor
There was a problem hiding this comment.
Pull request overview
This PR makes neighbor-queue traversal safer by changing closest_notvisited() to return Option instead of panicking when no unvisited nodes remain, and updates search/ground-truth loops to consume that Option-based API.
Changes:
- Change
NeighborQueue::closest_notvisited()/NeighborPriorityQueue::closest_notvisited()to returnOption<Neighbor<_>>and tightenset_visited()bounds. - Update multihop and main index search loops to use
while ... && let Some(...) = ...instead of relying onhas_notvisited_node()+ non-optional returns. - Update ground-truth generation to iterate with
while let Some(...).
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.
| File | Description |
|---|---|
| diskann/src/neighbor/queue.rs | Makes closest_notvisited() optional and adjusts visited bounds + some tests. |
| diskann/src/graph/search/multihop_search.rs | Updates beam-frontier selection loop to stop on None. |
| diskann/src/graph/index.rs | Updates core search beam-frontier selection loop to stop on None. |
| diskann-tools/src/utils/ground_truth.rs | Updates ground-truth queue draining loop to stop on None. |
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
hildebrandmw
approved these changes
Feb 20, 2026
Contributor
hildebrandmw
left a comment
hildebrandmw
left a comment
There was a problem hiding this comment.
I love everything about this. Thanks @arrayka! This is also a good check to make sure our CI checks that the experimental_diverse_search code does not break 😄
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #787 +/- ##
==========================================
- Coverage 89.00% 89.00% -0.01%
==========================================
Files 431 431
Lines 78445 78455 +10
==========================================
+ Hits 69821 69828 +7
- Misses 8624 8627 +3
Flags with carried forward coverage won't be shown. Click here to find out more.
🚀 New features to boost your workflow:
|
added 2 commits
February 20, 2026 10:24
hildebrandmw
approved these changes
Feb 20, 2026
Contributor
There was a problem hiding this comment.
Pull request overview
Copilot reviewed 6 out of 6 changed files in this pull request and generated no new comments.
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
metajack
approved these changes
Feb 20, 2026
Merged
hildebrandmw
added a commit
that referenced
this pull request
Feb 23, 2026
# DiskANN v0.47.0
## Summary
* This version contains a major breaking change to the search interface
of `DiskANNIndex`. Please read the upgrade instructions below.
* An Aarch64 Neon has been added to `diskann-wide`.
* Various bug-fixes and code-quality improvements.
## Changes to Search
The search interface has been unified around a single `index.search()`
entry point using the `Search` trait.
The old per-search-type methods on `DiskANNIndex` (`search`,
`search_recorded`, `range_search`, `multihop_search`) have been removed
and replaced by typed parameter structs that carry their own search
logic.
### What Changed
| Removed | Replacement |
|------------------------------------------------------------|--------------------------------------------------------------|
| `SearchParams` struct | `diskann::graph::search::Knn` |
| `RangeSearchParams` struct | `diskann::graph::search::Range` |
| `SearchParamsError` | `diskann::graph::KnnSearchError` |
| `RangeSearchParamsError` | `diskann::graph::RangeSearchError` |
| `index.search(&strategy, &ctx, &query, ¶ms, &mut out)` |
`index.search(knn, &strategy, &ctx, &query, &mut out)` |
| `index.search_recorded(..., &mut recorder)` |
`index.search(RecordedKnn::new(knn, &mut recorder), ...)` |
| `index.range_search(&strategy, &ctx, &query, ¶ms)` |
`index.search(range, &strategy, &ctx, &query, &mut ())` |
| `index.multihop_search(..., &label_eval)` |
`index.search(MultihopSearch::new(knn, &label_eval), ...)` |
| `index.diverse_search(...)` | `index.search(Diverse::new(knn,
diverse_params), ...)` |
**`flat_search`** remains an inherent method on `DiskANNIndex`
Its `search_params` argument changed from `&SearchParams` to `&Knn`.
### Upgrade Instructions
#### 1. k-NN Search (`search`)
**Before:**
```rust
use diskann::graph::SearchParams;
let params = SearchParams::new(10, 100, None)?;
let stats = index.search(&strategy, &ctx, &query, ¶ms, &mut output).await?;
```
**After:**
```rust
use diskann::graph::{Search, search::Knn};
let params = Knn::new(10, 100, None)?;
// Note: params is now the FIRST argument (moved before strategy)
let stats = index.search(params, &strategy, &ctx, &query, &mut output).await?;
```
Key differences:
- `SearchParams` -> `Knn` (import from `diskann::graph::search::Knn`)
- `SearchParamsError` -> `KnnSearchError` (import from
`diskann::graph::KnnSearchError`)
- Search params moved to the **first** argument of `index.search()`
- `k_value`, `l_value` fields are now private; use `.k_value()`,
`.l_value()` accessors (return `NonZeroUsize`)
#### 2. Recorded/Debug Search (`search_recorded`)
**Before:**
```rust
use diskann::graph::SearchParams;
let params = SearchParams::new(10, 100, None)?;
let stats = index
.search_recorded(&strategy, &ctx, &query, ¶ms, &mut output, &mut recorder)
.await?;
```
**After:**
```rust
use diskann::graph::{Search, search::{Knn, RecordedKnn}};
let params = Knn::new(10, 100, None)?;
let recorded = RecordedKnn::new(params, &mut recorder);
let stats = index.search(recorded, &strategy, &ctx, &query, &mut output).await?;
```
#### 3. Range Search (`range_search`)
**Before:**
```rust
use diskann::graph::RangeSearchParams;
let params = RangeSearchParams::new(None, 100, None, 0.5, None, 1.0, 1.0)?;
let (stats, ids, distances) = index
.range_search(&strategy, &ctx, &query, ¶ms)
.await?;
```
**After:**
```rust
use diskann::graph::{
Search,
search::Range,
RangeSearchOutput,
};
// Simple form:
let params = Range::new(100, 0.5)?;
// Or full options form:
let params = Range::with_options(None, 100, None, 0.5, None, 1.0, 1.0)?;
// Note: output buffer is `&mut ()` — results come back in the return type
let result: RangeSearchOutput<_> = index
.search(params, &strategy, &ctx, &query, &mut ())
.await?;
// Access results:
let stats = result.stats;
let ids = result.ids; // Vec<O>
let distances = result.distances; // Vec<f32>
```
Key differences:
- `RangeSearchParams` -> `Range` (import from
`diskann::graph::search::Range`)
- `RangeSearchParamsError` -> `RangeSearchError` (import from
`diskann::graph::RangeSearchError`)
- Return type changed from `(SearchStats, Vec<O>, Vec<f32>)` to
`RangeSearchOutput<O>` (a struct with `.stats`, `.ids`, `.distances`
fields)
- Pass `&mut ()` as the output buffer
- Field `starting_l_value` -> constructor arg `starting_l` (accessor:
`.starting_l()`)
- Field `initial_search_slack` -> constructor arg `initial_slack`
(accessor: `.initial_slack()`)
- Field `range_search_slack` -> constructor arg `range_slack` (accessor:
`.range_slack()`)
#### 4. Multihop / Label-Filtered Search (`multihop_search`)
**Before:**
```rust
use diskann::graph::SearchParams;
let params = SearchParams::new(10, 100, None)?;
let stats = index
.multihop_search(&strategy, &ctx, &query, ¶ms, &mut output, &label_eval)
.await?;
```
**After:**
```rust
use diskann::graph::{Search, search::{Knn, MultihopSearch}};
let knn = Knn::new(10, 100, None)?;
let params = MultihopSearch::new(knn, &label_eval);
let stats = index.search(params, &strategy, &ctx, &query, &mut output).await?;
```
Key differences:
- `MultihopSearch` wraps a `Knn` -> label evaluator into a single params
object
- The label evaluator is part of the params, not a separate argument
#### 5. Flat Search (unchanged method, new param type)
**Before:**
```rust
use diskann::graph::SearchParams;
let params = SearchParams::new(10, 100, None)?;
index.flat_search(&strategy, &ctx, &query, &filter, ¶ms, &mut output).await?;
```
**After:**
```rust
use diskann::graph::search::Knn;
let params = Knn::new(10, 100, None)?;
index.flat_search(&strategy, &ctx, &query, &filter, ¶ms, &mut output).await?;
```
Only the parameter type changed (`SearchParams` -> `Knn`).
### Import Path Changes
| Old | New |
|------------------------------------------|--------------------------------------------------------|
| `diskann::graph::SearchParams` | `diskann::graph::search::Knn` |
| `diskann::graph::RangeSearchParams` | `diskann::graph::search::Range`
|
| `diskann::graph::SearchParamsError` | `diskann::graph::KnnSearchError`
|
| `diskann::graph::RangeSearchParamsError` |
`diskann::graph::RangeSearchError` |
| — | `diskann::graph::search::MultihopSearch` (new) |
| — | `diskann::graph::search::RecordedKnn` (new) |
| — | `diskann::graph::search::Diverse` (new, feature-gated) |
| — | `diskann::graph::Search` (trait, re-exported) |
| — | `diskann::graph::RangeSearchOutput` (re-exported) |
## Change List
* copy bftrees from the snapshot location to the save location by
@backurs in #783
* (RFC) Refactor search interface with unified SearchDispatch trait by
@narendatha in #773
* Make queue.closest_notvisited() safe and update call sites by @arrayka
in #787
* git ignore: Ignore local settings for claude code AI agent by @arrayka
in #789
* Enabling flag support in codecov by @arrayka in
#790
* Increase unit test coverage for diskann-tools crate by @Copilot in
#763
* Neon MVP by @hildebrandmw in
#777
* Adding GraphParams to be able to save graph parameters of index to
SavedParams by @backurs in #786
## New Contributors
* @narendatha made their first contribution in
#773
**Full Changelog**:
0.46.0...v0.47.0
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
4 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Why
closest_notvisited()assumes there is always at least one unvisited element. If that’s not true, it can perform an unsafe out‑of‑bounds access (whencursor == size). Today, callers must explicitly checkhas_notvisited_node()before callingclosest_notvisited()to uphold this assumption. The risk exists becauseassert!(index <= self.size)is not strict enough.set_visited()to avoid out‑of‑bounds access (whencursor == size).closest_notvisited()returnOptionto avoid panics when no unvisited nodes remain.What
closest_notvisited()now returnsOption, guard against empty, fixset_visitedbounds, update tests.has_notvisited_node()loops withOption-basedclosest_notvisited()handling in search loops.while let Some(...)forclosest_notvisited().