Cache API

This is a Cache API application implemented using Node.js, TypeScript, Express, and Jest. The application provides two types of caches: an LRU (Least Recently Used) cache and a TTL (Time to Live) cache. The caches can store any type of data such as strings, numbers, or objects. It can be accessed via RESTful endpoints.

Features

• Least Recently Used (LRU) Cache: Stores a maximum of N records and discards the least recently used entry when a new record is added beyond the limit.
• Time To Live (TTL) Cache: Stores records with a time-to-live of N seconds and discards entries that haven't been accessed within this period.
• Persistent Storage: Cache data files are saved to disk at regular intervals under the ./data directory and reloaded when the application starts.

Installation and Usage

Clone the repository

git clone git@github.com:joechoi-git/cache-api.git
cd cache-api

Install dependencies

npm install

Start the server

npm start

Run tests

npm test

Formats files

npm run format

Run the linter

npm run lint
npm run lint:fix

File Structure

cache-api/
│
├── src/
│ ├── cache/
│ │ ├── leastRecentlyUsedCache.ts
│ │ ├── timeToLiveCache.ts
│ │ └── types.ts
│ ├── controllers/
│ │ └── cache.ts
│ ├── utils/
│ │ └── file.ts
│ └── server.ts
│
├── tests/
│ ├── cache.test.ts
│ └── cacheEndpoints.test.ts
│
├── .eslintrc.json
├── .gitignore
├── .prettierrc
├── jest.config.js
├── package-lock.json
├── package.json
├── README.md
└── tsconfig.json

src/cache/

• leastRecentlyUsedCache.ts

  • Implements the LRU (Least Recently Used) cache. This cache holds a maximum of N items and removes the least recently used item when the limit is exceeded.
  • Ensures that cache data is loaded from disk on startup and saved to disk at regular intervals.

• timeToLiveCache.ts

  • Implements the TTL (Time to Live) cache. This cache stores items for a specified duration of N seconds, and removes items that have not been accessed within this period.
  • Ensures that cache data is loaded from disk on startup and saved to disk at regular intervals.

• types.ts

  • Defines a TypeScript interface for the cache operations, ensuring a consistent API for different cache types.

src/controllers/cache.ts

• Exports the cache methods from cache classes to be used in the routes.

src/utils/file.ts

• Contains utility functions for saving cache data to disk and loading it back, ensuring data persistence across application restarts.

src/server.ts

• Sets up the Express server and routes.
• Ensures that cache data is saved to disk on any failure.

tests/

• cache.test.ts

  • Contains unit tests for the leastRecentlyUsedCache and timeToLiveCache classes, ensuring they function correctly with multiple data types, including strings and numbers.

• cacheEndpoints.test.ts

  • Contains integration tests for the Express routes, ensuring that the API endpoints for creating, retrieving, updating, searching, and deleting cache entries work as expected.

API Documentation

POST /cache/:type

Create or update a cache entry

curl -X POST http://localhost:3000/cache/lru -H "Content-Type: application/json" -d '{"key": "testKey", "value": "testValue"}'
curl -X POST http://localhost:3000/cache/ttl -H "Content-Type: application/json" -d '{"key": "testKey", "value": "testValue"}'

GET /cache/:type/:key

Retrieve a cache entry

curl -X GET http://localhost:3000/cache/lru/testKey
curl -X GET http://localhost:3000/cache/ttl/testKey

PUT /cache/:type/:key

Update a cache entry

curl -X PUT http://localhost:3000/cache/lru/testKey -H "Content-Type: application/json" -d '{"value": "newValue"}'
curl -X PUT http://localhost:3000/cache/ttl/testKey -H "Content-Type: application/json" -d '{"value": "newValue"}'

GET /cache/:type/search

Search cache entries

curl -X GET http://localhost:3000/cache/lru/search?value=value
curl -X GET http://localhost:3000/cache/ttl/search?value=value

DELETE /cache/:type/:key

Delete a cache entry

curl -X DELETE http://localhost:3000/cache/lru/testKey
curl -X DELETE http://localhost:3000/cache/ttl/testKey