Advanced usage

Three thresholds for cache invalidation

It’s possible to employ three threshold times to control cache behaviour:

1. A time after which the cached item is considered ‘stale’. When a stale item is returned, an async job is triggered to refresh the item but the stale item is returned. This is controlled by the lifetime attribute of the Job class - the default value is 600 seconds (10 minutes).

2. A time after which the cached item is removed (a cache miss). If you have fetch_on_miss=True, then this will trigger a synchronous data fetch. This is controlled by the cache_ttl attribute of the Job class - the default value is 2592000 seconds, which is the maximum ttl that memcached supports.

3. A timeout value for the refresh job. If the cached item is not refreshed after this time, then another async refresh job will be triggered. This is controlled by the refresh_timeout attribute of the Job class and defaults to 60 seconds.