Homekv

HOMEKV - Highly Optimized & Memory Efficient Key Value Store

Basic

HomeKV is a Rust key-value store which support Atomicity. Atomicity is implemented by a MVCC storage, which also make Reading and Writing don't block each other so that they can run in parallel.

The core MVCC storage of HomeKV acts as RWLock<T>, but it's better. Because writes and multiple reads can be performed simultaneously, which means they are not block each other to reduce contention.

To make the implementation easier, HomeKV only use the BTreeMap in Rust standard lib. The drawback of it is that MVCC needs to clone the whole tree to maintain multiple versions. An improvement could be change the underlying data structure to B+Tree. But it will be more complicated and can not be done in a short time.

WIP: Making HomeKV a distributed system for large-scale data.

• Built-in Service Discovery - Gossip & Phi Accrual Failure Detector
• Efficiently Distributing Keys - Consistent Hashing
• Replication Strong Consistence - Raft
• More Storage Types - Fragmented LSM

Server Concurrency Model

HomeKV uses Rust Tonic as the GRPC package, which handles concurrent requests in Asynchronous Programming way to achieve high performance.

ProtoBuf service definition is at api/proto/homekv_service.proto

API

HomeKV provides a RPC service through GRPC, which includes the following APIs,

• get: get values for multiple keys
• set: set multiple key-value pairs transactionally
• del: del values for multiple keys transactionally
• metrics: show storage metrics, number of keys, size of total values, and number of commands

Build

# homekv/
.
├── Cargo.lock
├── Cargo.toml
├── README.md
├── api
│   └── proto
│       └── homekv_service.proto
├── build.rs
└── src
    ├── bin
    │   ├── hkvctl.rs
    │   └── homekv.rs
    ├── common
    │   ├── error.rs
    │   └── mod.rs
    ├── lib.rs
    └── storage
        ├── btree_store.rs
        ├── mod.rs
        └── mvcc.rs

Rust has a versatile build tool, Cargo, which make our building is very easy.

Rust ENV Preparation

Please follow the Official Rust Installation to use rustup tool to install Rust and Cargo.

Cargo Build

HomeKV provides a command-line client tool called hkvctl, and a server starter called homekv. They are both under the src/bin folder, which will be built as binary executable files under target/release when we build this repo.

We just need to run the following command under the root folder of this repo.

# switch pwd to homekv
cargo build --release

Run

Start homekv server

# switch pwd to homekv
./target/release/homekv -h 127.0.0.1 -p 20001

Play with the cli

# switch pwd to homekv

# Set key/keys by specifying `cmd` as `set` and `kvs` as 1/n key-value pairs
./target/release/hkvctl -h 127.0.0.1 -p 20001  --cmd set --kvs dummy_key=🦫
./target/release/hkvctl -h 127.0.0.1 -p 20001  --cmd set --kvs trail=big_cedder people=5 start_time=12:00

# Get key/keys by specifying `cmd` as `get` and `keys` as 1/n keys
./target/release/hkvctl -h 127.0.0.1 -p 20001  --cmd get --keys dummy_key
./target/release/hkvctl -h 127.0.0.1 -p 20001  --cmd get --keys trail people
# Not existing keys
./target/release/hkvctl -h 127.0.0.1 -p 20001  --cmd get --keys end_time

# Delete key/keys by specifying `cmd` as `del` and `keys` as 1/n keys
./target/release/hkvctl -h 127.0.0.1 -p 20001  --cmd del --keys dummy_key
./target/release/hkvctl -h 127.0.0.1 -p 20001  --cmd del --keys people start_time
# Not existing keys
./target/release/hkvctl -h 127.0.0.1 -p 20001  --cmd del --keys end_time

# Observability
./target/release/hkvctl -h 127.0.0.1 -p 20001  --cmd metrics