@huggingface/xetchunk-wasm

Content-defined chunking and hashing for Hugging Face Xet storage, matching the Rust reference implementation.

Uses gearhash-jit for fast GEAR rolling hash boundary detection and @huggingface/blake3-jit for BLAKE3 chunk hashing.

Usage

import { createChunker, nextBlock, finalize, getChunks, hashToHex, xorbHash, fileHash } from '@huggingface/xetchunk-wasm';

// One-shot: chunk all data at once
const data = new Uint8Array(1_000_000);
const chunks = getChunks(data);

console.log(`${chunks.length} chunks`);
console.log('xorb hash:', hashToHex(xorbHash(chunks)));
console.log('file hash:', hashToHex(fileHash(chunks)));

// Streaming: process data incrementally
const chunker = createChunker();

for await (const buf of source) {
  const chunks = nextBlock(chunker, buf);
  for (const chunk of chunks) {
    console.log(hashToHex(chunk.hash), chunk.length);
  }
}

const lastChunk = finalize(chunker);

API

Chunking

• createChunker(targetChunkSize?: number) — Create a chunker (default 64KB target).
• nextBlock(chunker, data: Uint8Array): Chunk[] — Feed data, get complete chunks.
• finalize(chunker): Chunk | null — Flush remaining data as a final chunk.
• getChunks(data: Uint8Array, targetChunkSize?: number): Chunk[] — One-shot convenience.

Hash functions

All hash functions return Uint8Array (32 bytes). Use hashToHex() to convert to hex strings.

• xorbHash(chunks: Chunk[]): Uint8Array — Merkle tree hash over chunks (matches Rust xorb_hash).
• fileHash(chunks: Chunk[]): Uint8Array — File-level hash (matches Rust file_hash).
• hmac(hash: Uint8Array, key: Uint8Array): Uint8Array — BLAKE3 keyed hash (matches Rust DataHash::hmac).
• verificationHash(chunkHashes: Uint8Array[]): Uint8Array — Range verification hash (matches Rust range_hash_from_chunks).

Utilities

• hashToHex(hash: Uint8Array): string — Convert 32-byte hash to hex string.
• hexToBytes(hex: string): Uint8Array — Convert 64-char hex string to 32 bytes.

Benchmarking

pnpm --filter @huggingface/xetchunk-wasm bench
# or with a specific file:
pnpm --filter @huggingface/xetchunk-wasm bench path/to/large-file