Behaviour specification for cache adapters in the Lotus framework.

All cache adapters must implement this behavior.

Cache adapters are only meant to be used internally by Lotus and should not be called directly by application code, as their implementation may change without notice.

Built-in Adapters

• Lotus.Cache.ETS - Default ETS-based local in-memory cache
• Lotus.Cache.Cachex - Cachex-based cache supporting local and distributed modes

Usage

Simply use the behavior in your adapter implementation:

defmodule MyApp.CustomCacheAdapter do
  use Lotus.Cache.Adapter

  # Implement required callbacks...
end

Configuration

Configure your chosen adapter in your application config:

config :lotus,
  cache: %{
    adapter: MyApp.CustomCacheAdapter,
    # adapter-specific options...
  }

Reach of each callback in a cluster

Every callback is called on the node that runs the query, with no attempt by Lotus to route it elsewhere. What the call reaches depends on the adapter's store:

scope/1 tells Lotus.Cache which of those two columns applies to delete/1 and to invalidate_tags/1, separately. For an operation the adapter answers :node, the facade relays the call to the other nodes over Lotus.Notifier, where Lotus.Cache.Relay applies the same call to that node's adapter. Values are never relayed: each node fills its own entries on its own misses. An operation the adapter answers :cluster for is trusted to reach every node by itself and is not relayed.

Tag bookkeeping is bounded by the entries it describes. An adapter drops a tag's record of a key once that key has expired, so a tag that is never invalidated does not grow for the life of the node.