kohakuvault 0.1.0

SQLite-backed KV store (Rust+PyO3) for large media blobs

KohakuVault

A high-performance, SQLite-backed key-value store for large media files. Rust core with a Pythonic dict-like interface.

Quick Start

from kohakuvault import KVault

# Dict-like interface for binary data
vault = KVault("media.db")
vault["thumbnail:123"] = image_bytes
vault["video:456"] = video_bytes

# Stream large files without loading into memory
with open("large_video.mp4", "rb") as f:
    vault.put_file("video:789", f)

# Write-back cache for bulk operations
vault.enable_cache(cap_bytes=64*1024*1024)
for i in range(1000):
    vault[f"frame:{i}"] = frame_data
vault.flush_cache()  # Batch commit to disk

Why KohakuVault?

• No external services: Single-file SQLite database, no Redis/memcached needed
• Memory efficient: Stream multi-GB files without loading into RAM
• Fast: Rust implementation with optional write-back caching
• Pythonic: Feels like a dict, works like a database

Installation

pip install kohakuvault  # When published to PyPI
pip install .            # From source

Development

Prerequisites: Python 3.10+, Rust (rustup.rs)

# Setup
git clone https://github.com/yourusername/kohakuvault.git
cd kohakuvault
python -m venv .venv && source .venv/bin/activate  # or .venv\Scripts\activate on Windows
pip install -e .[dev]
maturin develop  # Build Rust extension (once)

# Workflow
# - Edit Python files → changes live immediately
# - Edit Rust files → run `maturin develop` to rebuild

# Tools
pytest                  # Run tests
black src/kohakuvault   # Format Python
cargo fmt               # Format Rust
maturin build --release # Build production wheel

Usage

Basic Operations

vault = KVault("media.db")

# Dict-like interface
vault["key"] = b"value"
data = vault["key"]
del vault["key"]
if "key" in vault: ...

# Safe retrieval
data = vault.get("key", default=b"")

# Iteration
for key in vault:
    print(f"{key}: {len(vault[key])} bytes")

Streaming Large Files

vault = KVault("media.db", chunk_size=1024*1024)  # 1 MiB chunks

# Stream from file → vault
with open("large_video.mp4", "rb") as f:
    vault.put_file("video:789", f)

# Stream from vault → file
with open("output.mp4", "wb") as f:
    vault.get_to_file("video:789", f)

Bulk Operations with Caching

vault = KVault("media.db")
vault.enable_cache(cap_bytes=64*1024*1024, flush_threshold=16*1024*1024)

# Writes batched in memory
for i in range(1000):
    vault[f"item:{i}"] = data

vault.flush_cache()  # Commit all at once
vault.disable_cache()

Configuration

vault = KVault(
    path="media.db",
    chunk_size=2*1024*1024,   # Streaming chunk size
    retries=10,                # Retry attempts for busy DB
    enable_wal=True,           # Write-Ahead Logging
    cache_kb=20000,            # SQLite cache size
)

API Reference

Constructor

KVault(path, chunk_size=1048576, retries=4, backoff_base=0.02,
       table="kvault", enable_wal=True, page_size=4096,
       mmap_size=268435456, cache_kb=20000)

Methods

Storage

• put(key, value) - Store bytes
• put_file(key, reader, size=None, chunk_size=None) - Stream from file-like
• get(key, default=None) - Retrieve bytes
• get_to_file(key, writer, chunk_size=None) - Stream to file-like
• delete(key) - Remove key
• exists(key) - Check existence

Caching

• enable_cache(cap_bytes, flush_threshold) - Enable write-back cache
• disable_cache() - Disable and flush cache
• flush_cache() - Commit cached writes, returns count

Maintenance

• optimize() - VACUUM database
• close() - Flush and close

Dict Interface: vault[key], del vault[key], key in vault, len(vault), vault.keys(), vault.values(), vault.items(), etc.

Exceptions: KohakuVaultError, NotFound, DatabaseBusy, InvalidArgument, IoError

Architecture

Python wrapper (src/kohakuvault/proxy.py)
    ↓ PyO3 bindings
Rust core (src/kvault-rust/lib.rs)
    ↓ rusqlite
SQLite database (bundled)

Why hybrid? Rust handles SQLite operations safely and efficiently. Python provides the ergonomic dict-like interface.

Contributing

# Setup
git checkout -b feature-name
# Make changes
black src/kohakuvault && cargo fmt  # Format
pytest                               # Test
git commit && git push
# Open PR

Releasing

GitHub Actions automatically builds and publishes wheels to PyPI on git tags:

# 1. Update version in pyproject.toml and Cargo.toml
# 2. Create and push tag
git tag v0.1.0 && git push origin v0.1.0
# 3. Wheels auto-build for all platforms and publish to PyPI

See .github/RELEASE.md for detailed release instructions and required secrets setup.

License

MIT - see LICENSE