Nebulex is split into 2 main components:

• Nebulex.Cache - caches are wrappers around the in-memory data store. Via the cache, we can insert, retrieve, update and delete entries from the in-memory data store. A cache needs an adapter to communicate to the in-memory data store.

• Nebulex.Object - this is the struct used by caches to handle data back and forth, entries in cache are stored and retrieved as objects, but this is totally handled by the cache adapter.

In the following sections, we will provide an overview of those components and how they interact with each other. Feel free to access their respective module documentation for more specific examples, options and configuration.

If you want to quickly check a sample application using Nebulex, please check the getting started guide.

Caches

Nebulex.Cache is the wrapper around the Cache. We can define a cache as follows:

defmodule MyApp.MyCache do
  use Nebulex.Cache, otp_app: :my_app
end

Where the configuration for the Cache must be in your application environment, usually defined in your config/config.exs:

config :my_app, MyApp.MyCache,
  adapter: Nebulex.Adapters.Local,
  n_shards: 2,
  gc_interval: 3600,
  write_concurrency: true

Each cache in Nebulex defines a start_link/1 function that needs to be invoked before using the cache. In general, this function is not called directly, but used as part of your application supervision tree.

If your application was generated with a supervisor (by passing --sup to mix new) you will have a lib/my_app.ex file containing the application start callback that defines and starts your supervisor. You just need to edit the start/2 function to start the repo as a supervisor on your application’s supervisor:

defmodule MyApp do
  use Application

  def start(_type, _args) do
    import Supervisor.Spec

    children = [
      supervisor(MyApp.MyCache, [])
    ]

    ...
  end
end

Object

Nebulex.Object is the struct used by the caches to store and retrieve data.

By default, when you execute some operation (set, get, delete, etc.) over a cache entry, the cache returns only the value of that entry, but you can ask for return the whole object:

iex> MyCache.set "foo", "bar", return: :object
%Nebulex.Object{key: "foo", ttl: :infinity, value: "bar", version: 1493481403098321000}

iex> MyCache.get "foo", return: :object
%Nebulex.Object{key: "foo", ttl: :infinity, value: "bar", version: 1493481403098321000}

See Nebulex.Object to learn more about it.