HexagonDB

HexagonDB is a fast, in-memory key-value database written in Rust.
It supports concurrent client connections and provides Redis-like commands over TCP using the RESP (Redis Serialization Protocol).

Use with caution: this project is in early development and not yet stable.

Features

• In-Memory Key-Value Store: Fast read/write operations.
• RESP Protocol Support: Compatible with standard Redis clients (e.g., redis-cli).
• Data Types:
  • String: Basic key-value pairs.
  • List: Linked list operations (LPUSH, RPUSH, LPOP, RPOP, LLEN, LRANGE).
  • Hash: Field-value maps (HSET, HGET, HGETALL, HDEL).
• TTL & Expiration: Set expiration times on keys (EXPIRE, TTL, PERSIST).
• Persistence (AOF): Append-Only File persistence ensures data durability across restarts.
• Concurrency: Handles multiple clients simultaneously using a thread-per-connection model.
• Thread Safety: Uses Arc<Mutex<DB>> for safe concurrent access.

Commands

String Operations

• SET key value: Set the value of a key.
• GET key: Get the value of a key.
• DEL key: Delete a key.
• EXISTS key: Check if a key exists.
• INCR key: Increment the integer value of a key.
• DECR key: Decrement the integer value of a key.

List Operations

• LPUSH key value [value ...]: Prepend one or multiple values to a list.
• RPUSH key value [value ...]: Append one or multiple values to a list.
• LPOP key: Remove and get the first element in a list.
• RPOP key: Remove and get the last element in a list.
• LLEN key: Get the length of a list.
• LRANGE key start stop: Get a range of elements from a list.

Hash Operations

• HSET key field value: Set the string value of a hash field.
• HGET key field: Get the value of a hash field.
• HGETALL key: Get all fields and values in a hash.
• HDEL key field: Delete one or more hash fields.

Key Management

• KEYS pattern: Find all keys matching the given pattern.
• EXPIRE key seconds: Set a key's time to live in seconds.
• TTL key: Get the time to live for a key.
• PERSIST key: Remove the expiration from a key.

Usage

Starting the Server

cargo run --release

The server listens on 127.0.0.1:2112.

Connecting with redis-cli

You can use the standard redis-cli tool to connect:

redis-cli -p 2112

Example Session

$ redis-cli -p 2112
127.0.0.1:2112> SET mykey "Hello"
OK
127.0.0.1:2112> GET mykey
"Hello"
127.0.0.1:2112> EXPIRE mykey 10
(integer) 1
127.0.0.1:2112> TTL mykey
(integer) 8
127.0.0.1:2112> LPUSH mylist a b c
(integer) 3
127.0.0.1:2112> LRANGE mylist 0 -1
1) "c"
2) "b"
3) "a"
127.0.0.1:2112> HSET myhash field1 "value1"
(integer) 1
127.0.0.1:2112> HGETALL myhash
1) "field1"
2) "value1"

Architecture

• Thread-per-connection: Each client runs in a dedicated thread.
• Shared database access: Database wrapped in Arc<Mutex<>> for thread safety.
• RESP Protocol: Implements Redis Serialization Protocol for broad client compatibility.
• AOF Persistence: Writes all state-changing commands to database.aof for durability.
• Lazy Expiration: Keys are checked for expiration on access.

License

MIT