Cacher

Cacher is an in-memory database server. It's not meant for production usage; I've created this for learning purposes. The project has two programs, a server you can make TCP requests to and a CLI that can make requests to the server. Both are written in Go.

The server stores key-value pairs in memory using a hash table (Golang's built-in map). You can get, set, delete, and expire keys using four supported operations: GET, SET, DEL and EXP.

Running

You can run the server by compiling it or by running a Docker container:

• Building
  • make run/server
• Docker
  • make build/docker
  • make run/docker

Your can pass some arguments at server startup.

• -address=HOST:PORT changes the address the server listen. Default: :8595
• -persist=BOOL if true persists the data on disk on server shutdown. Default: false

Making requests

You can make requests to the server by opening a TCP connection to :8595 using any tool you prefer or the CLI.

• Building
  • make build/cli
  • ./bin/cli -operation SET -key foo -value bar
• Docker
  • make build/docker
  • make up/docker
  • docker exec -it cacher /usr/local/bin/cacher/cli -operation SET -key foo -value bar

How the protocol works

The protocol works in a simple way, there is a format to the request, and another format to the response. A request expects at least two values: an operation, a key and optionally a value. Example: SET foo bar Valid operations are:

• GET
  • retrieve a key from the store
  • expects a KEY
• SET
  • store a key-value pair
  • expects a KEY and a VALUE
• DEL
  • delete a key from the store
  • expects a KEY
• EXP
  • set an expiration date to a key
  • expects a KEY and a Unix timestamp

A response is expected to include two values: a status and a message. Example: ERROR should provide a value when operation is SET Valid statuses are:

• OK
• ERROR

To Do:

• TCP server
• In memory store
• ttl
• Gracefull shutdown
• CLI client
• Docker
• Persistence
• Logging level
• Configuration arguments