Question

I know it looks like a silly question , but how am I supposed to fetch some data to ruby object periodically ? or after number of tries ,

Lets say I have :

 @variable = SomeModel.all 

and I don’t wanna fetch the results all the time so I can do

 @variable ||= SomeModel.all 

But how am I supposed to do that every periodic time without using something like memcache or 3rd party solution ? Any tricky way to do such a thing ?

Thanks .

Answer 1

untested:

Cache ={}
def fetch(key, ttl)
  obj, timestamp = Cache[key]
  now = Time.now
  if obj.nil? || now - timestamp > ttl
    obj = yield
    Cache[key]=[obj, now]
  end 
  obj
end

usage:

variable = fetch(:variable, 10.seconds) { SomeModel.all }

If nil is also a valid value, just use a default :no_value_stored as the default when reading from the cache and change the if block.

Sidenote: this will likely blow up on you if the keys are too many, as the hash grows indefinitely, so you should clean it up manually or use weak references.