Hobbes

A Bitcask-like log-structured key-value store with an in-memory index, written in Rust

Link to the blog

Usage

• Clone and install the project

git clone https://github.com/anirudhsudhir/hobbes.git
cargo install --path .

• Start the server

./hobbes-server -h
Usage: hobbes-server [OPTIONS]

Options:
      --addr <addr>      set the server endpoint [default: 127.0.0.1:4000]
      --engine <engine>  set the storage engine [default: hobbes] [possible values: hobbes, sled]
  -h, --help             Print help
  -V, --version          Print version

hobbes-server

• Use the client to issue commands to the server

./hobbes -h
A Bitcask-like log structured key-value store written in Rust

Usage: hobbes [OPTIONS] <COMMAND>

Commands:
  get   return the value associated with a key
  set   store a key-value pair
  rm    delete a key-value pair from the store
  help  Print this message or the help of the given subcommand(s)

Options:
      --addr <addr>  set the endpoint to connect to [default: 127.0.0.1:4000]
  -h, --help         Print help
  -V, --version      Print version

hobbes set foo bar
hobbes get foo
hobbes rm foo

Features

• Single mutable and multiple immutable logs: The store uses the Bitcask architecture. At any instance, the storage directory contains a mutable write-ahead log as well as several immutable logs
• Log Compaction: The store compacts logs when the filesize hits a certain threshold for efficient disk utilisation

Storage engines

Hobbes offers pluggable storage backends. Currently, there are two choices:

• hobbes: The default engine with a Bitcask-like architecture, built from scratch
• sled: An alternate production engine with features such as ACID transactions (Github)

Client-server architecture

The key-value store is a server that listens for commands on the specified address. You may use a tool such as netcat instead of the hobbes client to send commands

echo "<length_of_cmd>\r\nSET\r\n<key>\r\n<val>\r\n" | nc <addr> <port>
echo "10\r\nGET\r\nfoo\r\n" | nc localhost 4000
echo "15\r\nSET\r\nfoo\r\nbar\r\n" | nc localhost 4000
echo "9\r\nRM\r\nfoo\r\n" | nc localhost 4000

The length of the command is prepended before being sent. For instance, GET\r\nfoo\r\n is 10 bytes long. 10\r\n is prefixed to the command and sent.

The command and arguments are separated and terminated by a carriage return line feed (CRLF)(\r\n).