vallejoj / cache-rules-everything-around-me

caching exercise for dev league students

DRAFT

Cache Rules Everything Around Me

Route: /slow is very slow (takes 5 seconds to respond)

Solution: implement caching using Redis!

Cache Miss flow

Implement a caching approach so that when the initial GET request to /api, it takes 5 seconds as usual with the exception that the response value will be saved to the cache.

Cache Hit flow

But all subsequent GET requests to /api should be served from the cache. This request should be instant, e.g. not take 5 seconds to respond. The cache should expire after 1 minute. After that the first GET request to /api will take 5 seconds to respond and the cache miss flow will occur

Implementation

A Express middleware module that can be imported onto any route on our server. The middleware function will check the cache store for the cached data for a route and serves the data in the cache back (cache hit) to the client. Otherwise, if the data has not been cached, the middleware lets the request fall-through and hit the route.

Module should have:

• a method which returns a function that can be mounted as middleware
• a method to save a key-value pair to the cache
• a method to retrieve a value from the cache

Testing

How does a non-cached request differ from a request served from cache? This is your baseline for your test specifications.

• request assertions with supertest
• test runner: mocha

Final Boss

Is there a way to achieve the goal without the getter and setter methods? Yes, but it might require some spoon-bending. After this step you will have built a caching middlware with base similarity to other popular express middlware modules. \o/ :sparkles:

Hint: "fall-through middlware"