# Introspection

> USearch for Rust

```rust
let description = index.describe()?;
println!("{} entries in {} bytes", description.size, description.memory_usage);
println!("dispatched to {} and {}", description.cpu_class, description.gpu_class);
println!("compiled for {}", usearch::capabilities_compiled());
println!("available here {}", usearch::capabilities_available());

let reachability = index.health()?;
println!("{} of {} entries reachable", reachability.reachable, reachability.audited);

println!("{} entries under {key}, contained: {}", index.count(key)?, index.contains(key)?);
```

`describe` reads the frozen metadata and the counters once each, so under concurrent insertions they may come from slightly different moments, and `memory_usage` excludes the executor's scratch.
`health` audits how much of the graph a search reaches from its landmarks; entries it misses stay unfound until a `refine` re-links them.
`contains` is the blocking shorthand for a nonzero `count`.

`use usearch::DenseIndexDescription;`

`use usearch::DenseReachability;`

`use usearch::CPUClass;`

`use usearch::GPUClass;`

`use usearch::*;`

## DenseIndexDescription

A live index's frozen metadata and current counters, each read once, so under concurrent insertions they may come from slightly different moments.

```rust
pub struct DenseIndexDescription
```

- `metadata` `DenseMetadata`: The frozen metric, quantization, dimensions and connectivity, as a checkpoint reports them.
- `size` `usize`: Stored entries.
- `capacity` `usize`: Entries hosted without growing again.
- `memory_usage` `usize`: Bytes the handle holds; traversal scratch is the executor's.
- `cpu_class` `&'static str`: The CPU class dispatch picked on this machine, as [`CPUClass`](#CPUClass) spells it.
- `gpu_class` `&'static str`: The GPU class dispatch picked on the index's devices; "unknown" for a host index.
- `shards_count` `usize`: Live shards.

Implements: `Clone`, `Copy`, `StructuralPartialEq`, `PartialEq`, `Eq`, `Debug`, `Hash`

## DenseReachability

One reachability audit: the population it judged, and how much of it a search reaches.

```rust
pub struct DenseReachability
```

- `audited` `usize`: Entries published when the audit started; compare `reachable` against this, never a later size.
- `reachable` `usize`: Of those, the entries a search reaches; the rest no search finds until a refinement re-links them.
- `sweeps` `usize`: Levels the sweep took to converge; the deepest shard's on a sharded handle.
- `back_sweeps` `usize`: Levels the sweep back toward the entry point took, where an audit sweeps both ways.

Implements: `Clone`, `Copy`, `StructuralPartialEq`, `PartialEq`, `Eq`, `Debug`, `Default`

## CPUClass

The CPU families USearch ships tuned variants for: dispatch reports its pick in this vocabulary, and a RAM or NVMe placement or executor may pin one.

```rust
pub enum CPUClass
```

- `Serial` = `1`: The portable floor: no SIMD assumptions.
- `IntelHaswell` = `2`: Haswell-class x86: AVX2 & FMA, the 256-bit floor.
- `IntelSierra` = `3`: Sierra Forest-class x86 - the E-core Xeons: AVX-VNNI and its successors without AVX-512.
- `IntelSkylake` = `4`: Skylake-class x86: the AVX-512 foundation tier.
- `IntelIcelake` = `5`: Icelake-class x86: AVX-512 VNNI & VPOPCNT.
- `AmdGenoa` = `6`: Genoa-class x86 - Zen 4 and newer: native bf16 dot products over AVX-512.
- `IntelSapphire` = `7`: Sapphire Rapids-class x86: the Genoa bundle plus AVX-512 FP16 and the AMX-BF16 & AMX-INT8
tiles.
- `IntelGranite` = `8`: Granite Rapids-class x86: the Sapphire Rapids bundle plus the AMX-FP16 tiles.
- `IntelDiamond` = `9`: Diamond Rapids-class x86: the Granite Rapids bundle plus AVX10.2's FP8 conversions.
- `AwsG2` = `10`: Graviton2-class Arm - Neoverse N1, the bare NEON floor.
- `AppleM2` = `11`: Armv8.6+ NEON: dot products, bf16 & f16 fused multiplies - Apple M2 class silicon.
- `AppleM4` = `12`: Apple M4-class Arm: the Armv8.6 NEON bundle plus the SME outer-product tiles.
- `AwsG5` = `13`: Graviton5-class Arm - Neoverse V3, Armv9.2.
- `NvidiaVera` = `14`: Vera-class Arm - NVIDIA's Armv9.2-generation cores with FP8 dot products.
- `AlibabaC930` = `15`: Alibaba C930-class RISC-V - T-Head's XuanTie core, RVA23 vectors.
- `Wasm32V128` = `16`: WebAssembly every engine loads: 32-bit, single-threaded, the fixed-width simd128 tier.
- `Wasm64Extended` = `17`: WebAssembly with relaxed SIMD, shared memory for real thread pools, and 64-bit
addressing.
- `Monoversioned` = `18`: The one class of a monoversioned build, with every capability its floor implies or its
preset vouches for.

Implements: `Clone`, `Copy`, `StructuralPartialEq`, `PartialEq`, `Eq`, `Debug`, `Hash`, `Display`

## GPUClass

The GPU families USearch ships tuned variants for, the device twin of [[`CPUClass`](#CPUClass)]: a VRAM placement or executor may pin one.

```rust
pub enum GPUClass
```

- `NvidiaAmpere` = `1`: Ampere-class NVIDIA and every GPU without a class of its own - A100, A10 & RTX 30.
- `NvidiaAda` = `2`: Ada-class NVIDIA - L4, L40S & RTX 40: the fp8 conversions.
- `NvidiaHopper` = `3`: Hopper-class NVIDIA - H100 & H200.
- `NvidiaBlackwell` = `4`: Blackwell-class NVIDIA - B200, B300 & GB300.
- `NvidiaBlackwellRtx` = `5`: Consumer Blackwell NVIDIA - RTX 50, RTX PRO 6000 & DGX Spark.
- `NvidiaRubin` = `6`: Rubin-class NVIDIA - the Vera-Rubin platform's device half.
- `AmdCdna3` = `7`: CDNA3 AMD - MI300X & MI325X: gfx942, FNUZ fp8.
- `AmdCdna4` = `8`: CDNA4 AMD - MI350X & MI355X: gfx950, OCP fp8.
- `AmdCdna5` = `9`: CDNA5 AMD - MI400: gfx1250.
- `AppleMetal7` = `10`: Apple7-family GPUs and every Apple GPU without a class of its own - M1 & M2.
- `AppleMetal9` = `11`: Apple9-family GPUs - M3 & M4.
- `AppleMetal10` = `12`: Apple10-family GPUs - M5.

Implements: `Clone`, `Copy`, `StructuralPartialEq`, `PartialEq`, `Eq`, `Debug`, `Hash`, `Display`

## version

The version of the linked library.

```rust
pub fn version() -> &'static str
```

## capabilities_compiled

Comma-separated hardware capabilities the library was compiled with.

```rust
pub fn capabilities_compiled() -> &'static str
```

## capabilities_available

Comma-separated hardware capabilities this machine offers at runtime.

```rust
pub fn capabilities_available() -> &'static str
```