[Borges-users] Re: and some more on caching

[Слепнев Владимир]

Well, it seems I just wrote a StateRegistry that uses WeakRef's, not 
Weak::.

I do not attach finalizers to anything, it's too buggy. Instead, I 
delete references to GC'd objects when I iterate over the cache making 
a snapshot.


require 'weakref'

class Borges::StateRegistry

   def initialize
     @wrefs = []
   end

   def register(obj)
     wref = WeakRef.new(obj)
     @wrefs << wref
   end

   ##
   # Restore the state of all objects in the registry from a
   # previously recorded snapshot.

   def restore_snapshot(snap)
     snap.each do |obj, copy|
       restore_object_from_snapshot(obj, copy)
     end
   end

   ##
   # Returns a snapshot of the current state of all registered
   # objects.

   def snapshot
     snapshot = {}
     removed = []
     gcWasDisabled = GC.disable
     @wrefs.each do |wref|
       if wref.weakref_alive? then
         obj = wref.__getobj__
         snapshot[obj] = obj.clone
       else removed<<wref 
       end
     end
     GC.enable unless gcWasDisabled

     @wrefs = @wrefs-removed
     return snapshot
   end

   private

   ##
   # Restore an individual object's state from a copy.

   def restore_object_from_snapshot(obj, copy)
     obj.instance_variables.each do |var|
       obj.instance_variable_set(var, copy.instance_variable_get(var))
     end
   end

end


What do you think? At least it works with my app... SushiNet is still 
buggy, but it's a SushiNet problem I think.

Vladimir Slepnev.