PiPNN 4/6: integrate disk build pipeline

[SeliMeli]

Integrates PiPNN graph output into the production disk-index build and serialization pipeline.

Review key points

• Explicit PiPNN selection is never silently replaced by Vamana.
• Existing graph policy, PQ/disk layout, and canonical serializer remain authoritative.
• Cross-crate serialization uses a narrow adjacency entry point; real-point/start metadata is validated.

Stack 4/6: #1290 → #1294

[Copilot]

Pull request overview

This PR integrates PiPNN graph construction into the DiskANN disk-index build pipeline and exposes it through the benchmark CLI inputs, including automated fixture-based tests to validate the new JSON configuration and execution paths.

Changes:

• Add a BuildAlgorithm selector (Vamana vs PiPNN) with JSON-facing PiPNN parameters, plus memory-estimate-based fallback to Vamana for disk builds.
• Implement PiPNN graph building adapters for disk builds and in-memory benchmark builds, including vector-store “flat prefix” access for dense layouts.
• Add a shared cached CLI fixture runner and new PiPNN benchmark fixtures (disk + in-memory) to validate end-to-end CLI wiring.

Reviewed changes

Copilot reviewed 33 out of 37 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
diskann-providers/src/utils/rayon_util.rs	Exposes underlying Rayon pool reference for APIs that need &rayon::ThreadPool.
diskann-providers/src/storage/mod.rs	Re-exports new adjacency-graph save helper.
diskann-providers/src/storage/bin.rs	Adds save_adjacency_graph for canonical adjacency graph serialization.
diskann-providers/src/model/graph/provider/async_/fast_memory_vector_provider.rs	Exposes unsafe dense-prefix slice access to support PiPNN build path.
diskann-providers/src/model/graph/provider/async_/common.rs	Implements AlignedMemoryVectorStore::flat_prefix and adds a contiguous-prefix test.
diskann-disk/src/lib.rs	Re-exports PiPNN parameters (feature-gated) and exposes build-algorithm selection.
diskann-disk/src/build/mod.rs	Re-exports BuildAlgorithm and (feature-gated) PiPNN parameters.
diskann-disk/src/build/configuration/mod.rs	Introduces build-algorithm configuration module and re-exports its types.
diskann-disk/src/build/configuration/disk_index_build_parameter.rs	Adds build_algorithm, PiPNN constructor, PiPNN config conversion, and memory-estimate-based fallback.
diskann-disk/src/build/configuration/build_algorithm.rs	New: serde-driven BuildAlgorithm enum and PiPNN JSON parameter struct.
diskann-disk/src/build/builder/build/pipnn.rs	New: PiPNN graph build adapter producing a canonical on-disk adjacency graph.
diskann-disk/src/build/builder/build/pipnn/tests.rs	New: disk-build integration tests for PiPNN selection, fallback, and header correctness.
diskann-disk/src/build/builder/build.rs	Routes graph construction to PiPNN (when selected) while keeping existing Vamana pipeline as default.
diskann-disk/Cargo.toml	Adds optional diskann-pipnn dependency + feature, plus test deps for new tests.
diskann-benchmark/src/main.rs	Refactors registry creation and adds PiPNN fixture test hook (feature-gated).
diskann-benchmark/src/inputs/graph_index.rs	Adds PiPNN build-algorithm selection for graph-index build inputs (feature-gated).
diskann-benchmark/src/inputs/disk.rs	Adds alpha, makes quantization_type optional, and adds disk build-algorithm selection + validation.
diskann-benchmark/src/index/build.rs	Adds PiPNN in-memory build path leveraging dense flat-prefix when possible.
diskann-benchmark/src/index/benchmarks.rs	Wires PiPNN build path selection into benchmark build flow.
diskann-benchmark/src/disk_index/build.rs	Wires disk BuildAlgorithm into disk-index build parameter construction.
diskann-benchmark/Cargo.toml	Adds optional PiPNN dependency/feature and enables fixture runner for dev-tests.
diskann-benchmark/tests/pipnn/inmemory/stdout.txt	New: expected output for in-memory PiPNN CLI fixture.
diskann-benchmark/tests/pipnn/inmemory/stdin.txt	New: commands for in-memory PiPNN CLI fixture.
diskann-benchmark/tests/pipnn/inmemory/input.json	New: PiPNN in-memory input JSON fixture.
diskann-benchmark/tests/pipnn/disk/stdout.txt	New: expected output for disk PiPNN CLI fixture.
diskann-benchmark/tests/pipnn/disk/stdin.txt	New: commands for disk PiPNN CLI fixture.
diskann-benchmark/tests/pipnn/disk/input.json	New: PiPNN disk input JSON fixture.
diskann-benchmark-runner/src/lib.rs	Exposes new fixture runner module for tests/downstream crates (feature-gated).
diskann-benchmark-runner/src/fixture.rs	New: shared cached CLI fixture runner implementation.
diskann-benchmark-runner/src/fixture/tests.rs	New: unit tests for fixture runner behavior.
diskann-benchmark-runner/src/app.rs	Updates integration-test documentation and switches tests to the shared fixture runner.
diskann-benchmark-runner/Cargo.toml	Adds test-fixtures feature + optional tempfile dep for downstream fixture usage.
Cargo.lock	Adds/records diskann-pipnn and serde_json dependency changes.
.cargo/mutants.toml	Excludes new fixture overwrite behavior from mutation testing.

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[Copilot]

Pull request overview

Copilot reviewed 12 out of 13 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (2)

diskann-disk/src/build/configuration/disk_index_build_parameter.rs:17

• estimate_pipnn_peak_memory uses size_of::<...>() unqualified, but this module doesn’t import std::mem::size_of. This will fail to compile under the repo’s Rust toolchain.

use std::num::NonZeroUsize;

use diskann::ANNError;
#[cfg(feature = "pipnn")]
use diskann::ANNResult;
use thiserror::Error;

#[cfg(feature = "pipnn")]
use super::PiPNNParameters;
use super::{BuildAlgorithm, QuantizationType};

diskann-disk/src/build/configuration/disk_index_build_parameter.rs:113

• DiskIndexBuildParameters is publicly re-exported (via diskann-disk’s public API) and this change removes Copy from its derives. That is a breaking API change for downstream users that relied on implicit copies; if this is intentional, it should be called out explicitly (and potentially gated or versioned accordingly).

/// Parameters specific for disk index construction.
#[derive(Clone, PartialEq, Debug)]
pub struct DiskIndexBuildParameters {

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[Copilot]

Pull request overview

Copilot reviewed 12 out of 13 changed files in this pull request and generated 1 comment.