Caching interface specific for Plausible. Usage:

use Plausible.Cache

# - Implement the callbacks required
# - Optionally override `unwrap_cache_keys/1`
# - Populate the cache with `Plausible.Cache.Warmer`

Serves as a wrapper around Plausible.Cache.Adapter, where the underlying implementation can be transparently swapped.

Even though normally the relevant Adapter processes are started, cache access is disabled during tests via the :plausible, Elixir.Plausible.Cache, enabled: bool() application env key. This can be overridden on case by case basis, using the child specs options.

The base_db_query/0 callback is used to generate the base query that is executed on every cache refresh.

There are two modes of refresh operation: :all and :updated_recently; the former will invoke the query as is and clear all the existing entries, while the latter will attempt to limit the query to only the records that have been updated in the last 15 minutes and try to merge the new results with existing cache entries.

Both refresh modes are normally executed periodically from within a warmer process; see: Plausible.Cache.Warmer. The reason for two modes is that the latter is lighter on the database and can be executed more frequently.

When Cache is disabled via application env, the get/1 function falls back to pure database lookups (implemented via get_from_source/1 callback. This should help with introducing cached lookups in existing code, so that no existing tests should break.

Refreshing the cache emits telemetry event defined as per telemetry_event_refresh/2.