Getting Started

Starting Your Cache

To start a cache you can use either start/2 or start_link/2, and in general you should place it into your Supervision trees for fault tolerance. The first argument is the name of the cache and defines how you will communicate with your cache.

Supervisor.start_link(
  [ {Cachex, name: :my_cache} ]
)

The second and third arguments are both optional and represent cache and server options respectively. Cache options can be set on a cache at startup and cannot be modified. They're defined on a per-cache basis and control the features available to the cache. This table contains a summary of most of the available options, but please look at the module documentation either in GitHub or on Hexdocs for full documentation on what each one can configure.

OptionsValuesDescription
commandsmap or keywordA collection of custom commands to attach to the cache.
expirationexpiration()An expiration options record imported from Cachex.Spec.
fallbackfunction or fallback()A fallback record imported from Cachex.Spec.
hookslist of hook()A list of execution hooks to listen on cache actions.
limita limit() recordAn integer or Limit struct to define the bounds of this cache.
statsbooleanWhether to track statistics for this cache or not.
transactionalbooleanWhether to turn on transactions at cache start.
warmerslist of warmer()A list of cache warmers to enable on the cache.

Main Interface

The Cachex interface follows a specific standard to make it easier to predict and more user friendly. All calls should follow the pattern of having the cache argument first, followed by any required arguments and ending with an optional list of options (even if no options are currently used). All calls should result in a value in the format of { status, result } where status is usually :ok or :error (however this differs depending on the call). The result can basically be anything, as there are a number of custom controlled return values available inside Cachex.

In the interest of convenience all Cachex actions have an automatically generated "unsafe" equivalent (appended with !) which unwraps these result Tuples. This unwrapping assumes that :error status means that the result should be raised, and that any other status should just return the result itself.

iex(1)> Cachex.get(:my_cache, "key")
{:ok, nil}
iex(2)> Cachex.get!(:my_cache, "key")
nil
iex(3)> Cachex.get(:missing_cache, "key")
{:error, :no_cache}
iex(4)> Cachex.get!(:missing_cache, "key")
** (Cachex.ExecutionError) Specified cache not running
    (cachex) lib/cachex.ex:249: Cachex.get!/3

In production code I would typically recommend the safer versions to be explicit but the ! version exists for both convenience and unit test code to make assertions easier.