A UniqueAccessExpireLRUCache combines LRU caching and time based per entry expire caching. One can define for each cache entry a separate timepoint but also limit the size of the cache (per default: 1024). Each TValue object must thus offer the following method:

const Poco::Timespan& getTimeout() const;

which returns the relative timespan for how long the entry should be valid without being accessed! The absolute expire timepoint is calculated as now() + getTimeout(). Accessing an object will update this absolute expire timepoint. You can use the Poco::AccessExpirationDecorator to add the getExpiration method to values that do not have a getExpiration function.