Enable customization of Tokio runtimes in diskann-benchmark-core

[hildebrandmw]

Enable caller customization of the runtimes built with two new methods:

• diskann_benchmark_core::tokio::runtime_with: Construct a new runtime allowing the caller to customize the builder before creation.
• diskann_benchmark_core::search::search_all_with: Allow the caller to customize each runtime that gets created during the bulk search operation.

Downstream work has revealed the need to enable timing in the tokio runtimes. Instead of forcing all consumers of diskann-benchmark-core to opt-in to timing, this PR allows callers to opt-in selectively.

[Copilot]

Pull request overview

Adds public extension points so consumers of diskann-benchmark-core can customize Tokio runtime creation (e.g., opt-in Builder::enable_time) without changing the default runtime configuration used by the crate.

Changes:

• Add diskann_benchmark_core::tokio::runtime_with to allow caller customization of a preconfigured multi-thread runtime Builder.
• Add diskann_benchmark_core::search::search_all_with to apply a caller-provided builder callback to each runtime created during search_all.
• Extend/adjust tests and docs to cover the new APIs.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
diskann-benchmark-core/src/tokio.rs	Introduces runtime_with and adds tests validating customization and worker count.
diskann-benchmark-core/src/search/api.rs	Adds search_all_with, routes search_all through it, and extends tests/docs accordingly.

Comments suppressed due to low confidence (1)

diskann-benchmark-core/src/tokio.rs:28

• runtime_with duplicates the base builder setup currently done in runtime(). To avoid the two functions drifting if the default runtime configuration changes in the future, consider implementing runtime() in terms of runtime_with(num_threads, |_| {}) (or factoring out a shared helper that returns the preconfigured Builder).

pub fn runtime_with<F>(num_threads: usize, f: F) -> anyhow::Result<tokio::runtime::Runtime>
where
    F: FnOnce(&mut tokio::runtime::Builder),
{
    let mut builder = tokio::runtime::Builder::new_multi_thread();
    builder.worker_threads(num_threads);
    f(&mut builder);
    Ok(builder.build()?)

---

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 98.66667% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 89.46%. Comparing base (f206264) to head (79031b9).

Files with missing lines	Patch %	Lines
diskann-benchmark-core/src/tokio.rs	96.55%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #809   +/-   ##
=======================================
  Coverage   89.45%   89.46%           
=======================================
  Files         432      432           
  Lines       79452    79514   +62     
=======================================
+ Hits        71075    71136   +61     
- Misses       8377     8378    +1     

Flag	Coverage Δ
miri	89.46% <98.66%> (+<0.01%)	⬆️
unittests	89.31% <98.66%> (+<0.01%)	⬆️

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

Files with missing lines	Coverage Δ
diskann-benchmark-core/src/search/api.rs	97.84% <100.00%> (+0.20%)	⬆️
diskann-benchmark-core/src/tokio.rs	97.50% <96.55%> (-2.50%)	⬇️

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