oxiarc-snappy [Stable]

Pure Rust Snappy compression library, part of the OxiArc ecosystem.

Version: 0.3.3 (2026-06-06) | 112 tests passing

Features

Pure Rust — No C dependencies or unsafe FFI
Snappy block format — Fast in-memory compress/decompress
Snappy framing format — Streaming API with CRC32C checksums per chunk
Streaming API — FrameEncoder<W: Write> and FrameDecoder<R: Read> for incremental processing
SSE 4.2 CRC32C hardware acceleration — x86_64 builds use _mm_crc32_u64 intrinsics via runtime dispatch (OnceLock), falling back to pure-Rust software CRC32C automatically
Parallel frame compression — compress_parallel splits input into chunks and compresses them concurrently via Rayon (requires parallel feature flag)
Google Snappy interop — 16 integration tests validate wire-format compatibility against Google Snappy golden vectors

All features are implemented and tested. API is stable.

Quick Start

Add to your Cargo.toml:

[dependencies]
oxiarc-snappy = "0.3.3"

Block Format

use oxiarc_snappy::{compress, decompress};

let data = b"Hello, World! Hello, World!";
let compressed = compress(data);
let decompressed = decompress(&compressed)?;
assert_eq!(decompressed, data);

Framing Format (Streaming)

use oxiarc_snappy::{FrameEncoder, FrameDecoder};
use std::io::{Write, Read};

// Compress with streaming encoder
let mut compressed = Vec::new();
{
    let mut encoder = FrameEncoder::new(&mut compressed);
    encoder.write_all(b"Hello, streaming Snappy!")?;
    encoder.finish()?;
}

// Decompress with streaming decoder
let mut decoder = FrameDecoder::new(&compressed[..]);
let mut output = Vec::new();
decoder.read_to_end(&mut output)?;
assert_eq!(output, b"Hello, streaming Snappy!");

API Overview

Item	Kind	Description
`compress(data: &[u8]) -> Vec<u8>`	function	Snappy block compression
`decompress(data: &[u8]) -> Result<Vec<u8>, SnappyError>`	function	Snappy block decompression
`max_compress_len(input_len: usize) -> usize`	function	Upper bound on compressed size
`decompress_len(compressed: &[u8]) -> Result<usize, SnappyError>`	function	Decode uncompressed length from header
`crc32c(data: &[u8]) -> u32`	function	Castagnoli CRC32C checksum
`mask_checksum(crc: u32) -> u32`	function	Apply Snappy masking to CRC32C
`unmask_checksum(masked: u32) -> u32`	function	Remove Snappy masking from CRC32C
`masked_crc32c(data: &[u8]) -> u32`	function	Compute masked CRC32C in one step
`FrameEncoder<W>`	struct	Streaming framing encoder (implements `Write`)
`FrameDecoder<R>`	struct	Streaming framing decoder (implements `Read`)
`SnappyError`	enum	Error type for decompression and framing failures

Feature Flags

Feature	Default	Description
`parallel`	no	Multi-threaded frame compression via Rayon (`compress_parallel`)

All other functionality — block format, framing format, CRC32C (with SSE 4.2 hardware acceleration on x86_64) — is enabled by default.

[dependencies]
# Default (no parallel)
oxiarc-snappy = "0.3.3"

# With parallel compression
oxiarc-snappy = { version = "0.3.3", features = ["parallel"] }

CRC32C

The Snappy framing format requires a masked CRC32C checksum for each chunk. oxiarc-snappy includes a pure-Rust CRC32C implementation (Castagnoli polynomial, slicing-by-4 optimised).

Hardware Acceleration (SSE 4.2 on x86_64)

On x86_64 hosts, the CRC32C path is accelerated at runtime when SSE 4.2 is available:

Checks is_x86_feature_detected!("sse4.2") once at startup via OnceLock.
Fast path uses _mm_crc32_u64 (8 bytes/cycle), with _mm_crc32_u8 for trailing 1–7 bytes.
The output is bitwise-identical to the scalar path — no difference in correctness.
On non-x86_64 platforms (e.g. aarch64/macOS) and on x86_64 without SSE 4.2, the scalar fallback is used transparently.

What's new in 0.3.1

16 interop integration tests against Google Snappy wire-format golden vectors:

Empty input roundtrip
Single-byte roundtrip
64 KiB boundary roundtrip
64 KiB + 1 byte roundtrip
max_compress_len invariant verification
Arbitrary-data roundtrip
Crafted-stream decode
Truncated-varint rejection
Oversized-varint rejection
And 7 additional wire-format compatibility cases

Part of OxiArc

This crate is part of the OxiArc project — a Pure Rust archive and compression library ecosystem.

Documentation

Full API documentation: https://docs.rs/oxiarc-snappy

License

Apache-2.0

oxiarc-snappy 0.3.3