Unsure if `golang::last_version()` caching will be a problem

[danielparks]

Shortly I’ll be adding golang::last_version() to get the latest stable version of Go from https://go.dev/dl/?mode=json.

I’m concerned about the potential to hit https://go.dev with too many requests (though it seems unlikely to me that this module will ever be used enough to cause a problem). So, I’m considering adding simple memoization to the function:

Puppet::Functions.create_function(:"golang::latest_version") do
  # ...
  def latest_version(url)
    @@golang_latest_version_cache ||= {}
    @@golang_latest_version_cache[url] ||= load_latest_version(url)
  end
  # ...
end

I imagine this will last longer than the catalog compilation, which seems like it might be an issue — if it lives as long as the Puppet server, then it could last quite a long time.

• I could add expiration to the cache.
• I’m not sure if there are other downsides I’m not seeing, or better ways to do this.
• Maybe this isn’t necessary at all?

[danielparks]

  def latest_version(url)
    time = Process.clock_gettime(Process::CLOCK_MONOTONIC)
    @@golang_latest_version_cache ||= {} # rubocop:disable Style/ClassVars

    if !@@golang_latest_version_cache[url] \
        || time - @@golang_latest_version_cache[url][:time] >= 60
      @@golang_latest_version_cache[url] = {
        time: time,
        version: load_latest_version(url),
      }
    end

    @@golang_latest_version_cache[url][:version]
  end