Memoize

Memoize allows to cache certain expensive function calls and cache the result. The main advantage in Coraza is to memoize the regexes and aho-corasick dictionaries when the connects spins up more than one WAF in the same process and hence same regexes are being compiled over and over.

Currently it is opt-in under the memoize_builders build tag as under a misuse (e.g. using after build time) it could lead to a memory leak as currently the cache is global.

Important: Connectors with live reload functionality (e.g. Caddy) could lead to memory leaks which might or might not be negligible in most of the cases as usually config changes in a WAF are about a few rules, this is old objects will be still alive in memory until the program stops.