🤗 xet-core - xet client tech, used in huggingface_hub

Welcome

xet-core enables huggingface_hub to utilize xet storage for uploading and downloading to HF Hub. Xet storage provides chunk-based deduplication, efficient storage/retrieval with local disk caching, and backwards compatibility with Git LFS. This library is not meant to be used directly, and is instead intended to be used from huggingface_hub.

Key features

♻ chunk-based deduplication implementation: avoid transferring and storing chunks that are shared across binary files (models, datasets, etc).

🤗 Python bindings: bindings for huggingface_hub package.

↔ network communications: concurrent communication to HF Hub Xet backend services (CAS).

🔖 local disk caching: chunk-based cache that sits alongside the existing huggingface_hub disk cache.

Local Development

Repo Organization - Rust Crates

• cas_client: communication with CAS backend services, which include APIs for Xorbs and Shards.
• cas_object: CAS object (Xorb) format and associated APIs, including chunks (ranges within Xorbs).
• cas_types: common types shared across crates in xet-core and xetcas.
• chunk_cache: local disk cache of Xorb chunks.
• chunk_cache_bench: benchmarking crate for chunk_cache.
• data: main driver for client operations - FilePointerTranslator drives hydrating or shrinking files, chunking + deduplication here.
• error_printer: utility for printing errors conveniently.
• file_utils: SafeFileCreator utility, used by chunk_cache.
• hf_xet: Python integration with Rust code, uses maturin to build hfxet Python package. Main integration with HF Hub Python package.
• mdb_shard: Shard operations, including Shard format, dedupe probing, benchmarks, and utilities.
• merkledb: Xorb hash creation.
• merklehash: DataHash type, 256-bit hash, widely used across many crates.
• parutils: Provides parallel execution utilities relying on Tokio (ex. parallel foreach).
• progress_reporting: offers ReportedWriter so progress for Writer operations can be displayed.
• utils: general utilities, including singleflight, progress, serialization_utils and threadpool.

Build, Test & Benchmark

To build xet-core, look at requirements in GitHub Actions CI Workflow for the Rust toolchain to install. Follow Rust documentation for installing rustup and that version of the toolchain. Use the following steps for building, testing, benchmarking.

Many of us on the team use VSCode, so we have checked in some settings in the .vscode directory. Install the rust-analyzer extension.

Build:

cargo build

Test:

cargo test

Benchmark:

cargo bench

Linting:

cargo clippy -r --verbose -- -D warnings

Formatting (requires nightly toolchain):

cargo +nightly fmt --manifest-path ./Cargo.toml --all

Building Python package and running locally (on *nix systems):

1. Create Python3 virtualenv: python3 -mvenv ~/venv
2. Activate virtualenv: source ~/venv/bin/activate
3. Install maturin: pip3 install maturin ipython
4. Go to hf_xet crate: cd hf_xet
5. Build: maturin develop
6. Test:

ipython
import hfxet 
hfxet.upload_files()
hfxet.download_files()

Building universal whl for MacOS:

From hf_xet directory:

MACOSX_DEPLOYMENT_TARGET=10.9 maturin build --release --target universal2-apple-darwin --features openssl_vendored

Note: You may need to install x86_64: rustup target add x86_64-apple-darwin

Testing

Unit-tests are run with cargo test, benchmarks are run with cargo bench. Some crates have a main.rs that can be run for manual testing.

Contributions (feature requests, bugs, etc.) are encouraged & appreciated 💙💚💛💜🧡❤️

Please join us in making xet-core better. We value everyone's contributions. Code is not the only way to help. Answering questions, helping each other, improving documentation, filing issues all help immensely. If you are interested in contributing (please do!), check out the contribution guide for this repository.

Debugging

To limit the size our our built binaries, we are releasing python wheels with binaries that are stripped of debugging symbols. If you encounter a panic while running hf-xet, you can use the debug symbols to help identify the part of the library that failed.

Here are the recommended steps:

1. Download and unzip our debug symbols package.
2. Determine the location of the hf-xet package using pip show hf-xet. The Location field will show the location of all the site packages. The hf_xet package will be within that directory.
3. Determine the symbols to copy based on the system you are running:
   • Windows: use hf_xet.pdb
   • Mac: use libhf_xet-macosx-x86_64.dylib.dSYM for Intel based Macs and libhf_xet-macosx-aarch64.dylib.dSYM for Apple Silicon.
   • Linux: the choice will depend on the architecture and wheel distribution used. To get this information, cat the WHEEL file name within the hf_xet.dist-info directory in your site packages. The wheel file will have the linux build and architecture in the file name. Eg: cat /home/ubuntu/.venv/lib/python3.12/site-packages/hf_xet-*.dist-info/WHEEL. You will use the file named hf_xet-<manylinux | musllinux>-<x86_64 | arm64>.abi3.so.dbg choosing the distribution and platform that matches your wheel. Eg: hf_xet-manylinux-x86_64.abi3.so.dbg.
4. Copy the symbols to the site package path from step 2 above + hf_xet. Eg: cp -r hf_xet-1.1.2-manylinux-x86_64.abi3.so.dbg /home/ubuntu/.venv/lib/python3.12/site-packages/hf_xet
5. Run your python binary with RUST_BACKTRACE=full and recreate your failure.

References & History

• Technical Blog posts
• Git is for Data 'CIDR paper
• History: xet-core is adapted from xet-core, which contains deep git integration, along with very different backend services implementation.