Problem

We need to cache large json objects to decrease number db calls and to reduce cpu and memory usage

Solution

Use lru cache in band with hashed objects as a keys

Why lru?

• very scalable solution (instead of widely used memoization libs), it allows to control size of the cache, ttl for keys
• we need lru to avoid redundant db calls and heavy weight ops for most recently used set of args (least recently used would be removed from the cache)

Why crypto module is changed?

• i am using blake2b512 cause it is prefered for large json objects hashing and it is presented in default js crypto lib see

Todo

• probably lodash.memoize lib could be replaced with this implementation
• tests
• lint

Risks

• probably hashing of large jsons could be the bottleneck (we could spend more resources for hashing than for db calls) — higher cpu usage
• higher memo usage (cause we store ~50 large objects for each memoized method of the worker)

all of the risks could be solved by the configuration of the cache max elements (i've set to 50 just for example, should be descussed), maybe we can use maxSize of the lru-cache and allow dynamically decide whenever to add a new object to the cache or not

also ttl value should be discussed, but it is placed in env