/remote_code_exercise

Primary LanguageElixir

CodeExercise

This app listen to the port 3000 on http://localhost/ returning a json with a list of 2 users that matches a particular amount of points in the format of:

{
  "users": [{"id": 1, "points": 10}, {"id": 1, "points": 10}],
  "timestamp": "2021-12-07T06:57:00.00000"
}

The amount of points rotates every minute and are in a range of [0-100]

Each minute a process updates every user to add a random point to it.

Technical decisions

In order to comply with the initial requirements of seed 1_000_000 users, I opted to make the seeds use Ecto.Repo.insert_all/3 to insert the users in batches of 10_000, to speed up the process.

The same apply for the GenServer that updates every user to set a random value for points on each user. To be able to update the users in a timely way, I opted to use Ecto.Repo.insert_all/3 again with upsert clauses, to update the users in batches, and setting a different random number on the points field.

On the Genserver, I also opted to update the users inside a concurrent Task to not block the GenServer queue. The task will not be awaited as the results of this operation are not needed.

Setup

The app was built using Elixir ~> 1.12.2, Erlang 24.

  • Install dependencies with mix deps.get
  • Create and migrate your database with mix ecto.setup
  • Start Phoenix endpoint with mix phx.server or inside IEx with iex -S mix phx.server

Database dev/test

To connect to database on dev/test environment, the app expects to exist a PostgreSQL role with permission to create database with the following login:

  • username: remote_user
  • password: remote

Production Environment Variables

The app will look for the following environment variables when initializing on a prod environment

  • DATABASE_URL (mandatory) like postgres://user:pass@host/database
  • SECRET_KEY_BASE (mandatory)
  • POOL_SIZE (optional fallbacks to 10)
  • PORT (optional fallbacks to 3000)