Many of answers you replied are reasonable and good.
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And I just want to add more comments for others.
1. SIEVE is not scan-resistant, so that, I think it should only be applied for web cache workloads (typlically follows power-law distribution)
2. SIEVE is somewhat scalalbe for read-intensive applications (e.g. blog, shop and etc), because it doesn't require to hold a lock on cahce hit.
3. The purpose of golang-fifo is to provide simple and efficient cache implementation (e.g. hashicorp-lru, groupcache).
-> I don't want to beat high-performant, bla-bla, specialized in-memory caches (bigcache, fastcache and etc).
-> Both S3-FIFO and SEIVE have O(n) worst-case cache eviction. and it only happens when all of objects in the cache are hit, which means, a perfect(100%) hit rate in sequences.
4. when increasing contention otter sacrifices 1-2 percent
-> I think that the statement is not enough. The hit rate varies depending on the total number of objects and the size of the cache, so it should be compared relatively. for example, otter's efficiency decreased by 5% compared to single-threaded when lock contention increased (decreased efficiency makes a mean network latency higher, because it may need to conduct heavy operation e.g. re-calculation, database access and so on)
-> Therefore, in certain situations, the efficiency of a cache library may be more important than its QPS. This is not a matter of which one is better, but rather that other people should be able to choose a cache library that suits the specific needs of their application.
5. ghost queue : honetly at that time of writing the code, I didn't deep dive into the bucket table implementation, it may not work same as actual bucket hash table (see here: https://github.com/scalalang2/golang-fifo/issues/16)
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