0 will * effectively disable early expiration, and by extension disable stampede * mitigation altogether. * * A greater value may be suitable if a source has a highly variable * generation duration, but most implementations should simply return * 1.0. * * @link https://en.wikipedia.org/wiki/Cache_stampede#Probabilistic_early_expiration * @link https://cseweb.ucsd.edu/~avattani/papers/cache_stampede.pdf * * Optimal Probabilistic Cache Stampede Prevention * Vattani, A.; Chierichetti, F.; Lowenstein, K. (2015), "Optimal * Probabilistic Cache Stampede Prevention" (PDF), Proceedings of the VLDB * Endowment, VLDB, 8 (8): 886–897, doi:10.14778/2757807.2757813, ISSN * 2150-8097 https://cseweb.ucsd.edu/~avattani/papers/cache_stampede.pdf * * @return float */ public function getExpiryWeight(): float; /** * Returns a deterministically computed key for use in caching settings * from this source. * * @return string */ public function getHashKey(): string; }