kachedb

High-Performance Python Client for KacheDB — The Zero-Copy Redis-Compatible & LLM KV-Cache Storage Engine

⚡ Installation

pip install kachedb

Installation Extras:

# PyTorch tensor zero-copy support (FP16, BF16, FP32, INT8)
pip install "kachedb[torch]"

# vLLM PagedAttention KV-transfer plugin
pip install "kachedb[vllm]"

# SGLang RadixAttention KV-cache plugin
pip install "kachedb[sglang]"

# Install all plugins & dependencies
pip install "kachedb[all]"

🚀 Quickstart

Synchronous Client

from kachedb import KacheClient

with KacheClient(host="127.0.0.1", port=6379) as client:
    # Standard Redis-compatible operations
    client.set("user:1", "alice", ex=3600)  # SET with 1-hour TTL
    print(client.get("user:1"))  # b"alice"

    # Batch operations
    client.set("user:2", "bob")
    result = client.mget("user:1", "user:2")  # [b"alice", b"bob"]

    # Check existence
    print(client.exists("user:1"))  # 1

    # Delete
    client.delete("user:1", "user:2")

Async Client

import asyncio
from kachedb import AsyncKacheClient


async def main():
    async with AsyncKacheClient(host="127.0.0.1", port=6379) as client:
        await client.set("key", "value", ex=60)
        result = await client.get("key")
        print(result)  # b"value"


asyncio.run(main())

Pipeline Batching

from kachedb import KacheClient

with KacheClient() as client:
    pipe = client.pipeline()
    pipe.set("a", "1")
    pipe.set("b", "2")
    pipe.set("c", "3")
    pipe.get("a")
    pipe.get("b")
    pipe.get("c")

    results = pipe.execute()
    # ["OK", "OK", "OK", b"1", b"2", b"3"]

🧠 LLM KV-Cache Acceleration (vLLM & SGLang)

KacheDB serves as a high-speed, zero-copy L1/L2 KV-Cache Tier for AI inference engines, bypassing quadratic transformer attention prefill passes via POSIX shared memory (/dev/shm):

1. 🔌 vLLM PagedAttention Integration

Launch vLLM with the KacheDB KV connector:

vllm serve meta-llama/Meta-Llama-3-8B-Instruct \
  --kv-transfer-config '{"kv_connector": "kachedb.vllm.KacheDBConnector", "kv_role": "kv_both"}'

Programmatic Usage:

from kachedb.vllm import KacheDBConnector

connector = KacheDBConnector(rank=0, local_rank=0, block_size=16)

# Restore prefix blocks directly into GPU PagedAttention buffers
matched_states, is_hit = connector.recv_kv_caches_and_hidden_states(
    model_executable=model,
    model_input=model_input,
    kv_caches=gpu_kv_caches,
)

👉 Read the full vLLM Production Integration Guide.

2. 🌳 SGLang RadixAttention Integration

Use KacheDBSGLangConnector to offload and restore dynamic Radix tree branches:

from kachedb.sglang import KacheDBSGLangConnector

connector = KacheDBSGLangConnector(rank=0, local_rank=0, pool_size_mb=2048)

# 1. Offload an evicted Radix tree node (Variable-length token slice)
desc = connector.offload_node(
    node_id=node.id,
    token_ids=node.token_ids,
    k_tensors=node_k_tensors,
    v_tensors=node_v_tensors,
    parent_hash=parent_hash,
)

# 2. Restore cached prefix subtree directly into target GPU/CPU memory
matched_tokens, is_hit = connector.restore_prefix(
    prompt_tokens=incoming_prompt_token_ids,
    target_k_buffers=target_k_buffers,
    target_v_buffers=target_v_buffers,
)

👉 Read the full SGLang Production Integration Guide.

⚡ Master Proof-of-Speed Benchmarks

Evaluated on Meta-Llama-3-8B Topology (32 Layers, 8 KV Heads, FP16) connected to the live KacheDB storage engine:

📋 Supported Commands

All commands follow the KacheDB RESP2/RESP3 wire protocol:

🏗️ Architecture

┌──────────────────────────────────────────────────────────┐
│                     Your Python App                      │
│             (vLLM / SGLang / FastAPI / etc.)             │
├──────────────────────────────────────────────────────────┤
│                   kachedb Python SDK                     │
│  ┌──────────────┐  ┌──────────────┐  ┌────────────────┐  │
│  │ KacheClient  │  │  AsyncKache  │  │    Pipeline    │  │
│  │  (sync TCP)  │  │    Client    │  │    Batching    │  │
│  └──────┬───────┘  └──────┬───────┘  └───────┬────────┘  │
│         │                 │                  │           │
│  ┌──────┴─────────────────┴──────────────────┴────────┐  │
│  │            RESP2/RESP3 Protocol Engine             │  │
│  │         (64KB buffered encoder + decoder)          │  │
│  └──────────────────────┬─────────────────────────────┘  │
│                         │                                │
│  ┌──────────────────────┴─────────────────────────────┐  │
│  │        ConnectionPool / AsyncConnectionPool        │  │
│  │    (Thread-safe / asyncio.Queue, health checks)    │  │
│  └──────────────────────┬─────────────────────────────┘  │
├─────────────────────────┼────────────────────────────────┤
│                   TCP + /dev/shm                         │
├──────────────────────────────────────────────────────────┤
│                  KacheDB Server (Rust)                   │
│         io_uring / kqueue │ POSIX SHM │ Megaslab         │
└──────────────────────────────────────────────────────────┘

🧪 Development & Quality Gates

# Clone
git clone https://github.com/vubon/kachedb-py.git
cd kachedb-py

# Install in editable dev mode with all extras
pip install -e ".[all,dev]"

# Run full unit test suite (85 tests)
pytest tests/ -v

# Code formatting & linting
ruff check src/ tests/
ruff format --check src/ tests/

# Strict type checking
mypy src/

🔗 Documentation & Guides

• 📘 vLLM Production Integration Guide
• 📗 SGLang Production Integration Guide
• 🏆 Master Proof-of-Speed Benchmarks
• 🦀 KacheDB Rust Server Engine

📄 License

Dual-licensed under either of:

• Apache License, Version 2.0 (LICENSE-APACHE)
• MIT license (LICENSE-MIT) at your option.