# `ExDataSketch.Backend.Rust`
[🔗](https://github.com/thanos/ex_data_sketch/blob/main/lib/ex_data_sketch/backend/rust.ex#L1)

Rust NIF-accelerated backend for ExDataSketch.

Delegates batch and full-state traversal operations to Rust NIFs for
performance, while falling back to `ExDataSketch.Backend.Pure` for
lightweight operations like `new`, single `update`, and point queries.

## Availability

This backend is only available when the Rust NIF has been compiled.
Check with `ExDataSketch.Backend.Rust.available?/0`.

## Dirty Scheduler Thresholds

Batch operations automatically use dirty CPU schedulers when the input
size exceeds configurable thresholds. Defaults:

- `hll_update_many`: 10,000 hashes
- `ull_update_many`: 10,000 hashes
- `ull_merge`: 50,000 registers (m = 2^p)
- `ull_estimate`: 50,000 registers (m = 2^p)
- `cms_update_many`: 10,000 pairs
- `theta_update_many`: 10,000 hashes
- `cms_merge`: 100,000 total counters
- `theta_compact`: 50,000 entries
- `theta_merge`: 50,000 combined entries
- `kll_update_many`: 10,000 values
- `kll_merge`: 50,000 combined items
- `ddsketch_update_many`: 10,000 values
- `ddsketch_merge`: 50,000 combined count
- `fi_update_many`: 10,000 items
- `fi_merge`: 50,000 combined entries
- `fi_nif_query`: 256 (k threshold for `fi_top_k`/`fi_estimate`; below this, Pure is used)

Override globally via application config:

    config :ex_data_sketch, :dirty_thresholds, %{
      hll_update_many: 5_000,
      cms_update_many: 20_000
    }

Or per-call via the `:dirty_threshold` option.

# `available?`

```elixir
@spec available?() :: boolean()
```

Returns `true` if the Rust NIF is loaded and available.

## Examples

    iex> is_boolean(ExDataSketch.Backend.Rust.available?())
    true

# `cms_update_many_raw`

# `hll_update_many_raw`

# `theta_update_many_raw`

# `ull_update_many_raw`

---

*Consult [api-reference.md](api-reference.md) for complete listing*