Creates a module to wrap cache operations. This is the preferred way to create a cache as it performs better.

    defmodule App.Cache do
        require DCache
        DCache.define(Users, 100_000)  # creates an App.Cache.Users module
    end

opts:

cache: Module
    The name of the module to create. This will be nested within the calling module

max: integer
    The maximum number of items to hold in the cache

opts:
    segments: integer
        The number of segments to create (defaults to 10)

Delets the value from the cache, safe to call even if the key is not in the cache

Same as fetch, but unwraps the returned value or raises on error.

Gets the value from the cache. Executes fun/1 if the value is not found. fun/1 receives the cache key being looked up and should return one of:

* `{:ok, value}`
* `{:ok, value, ttl}`
* `{:skip, value}`
* `{:error, term}`

Gets the value from the cache, returning nil if not found or expired

Puts the value in the cache. TTL is a relative time in second. For example, 300 would mean that the value would expire in 5 minutes

Creates the cache opts:

cache: atom
    The name of the cache

max: integer
    The maximum number of items to hold in the cache

opts:
    segments: integer
        The number of segments to create (defaults to 10)

Returns the total number of items in the cache, including expired items. This is O(N) over the number of segments

Gets the unix time in seconds when the value will be considered expired. Rrturns nil if the value is not found. The return value can be in the past