13c13
< require 'thread'
---
> require 'monitor'
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<   @@mutex = Mutex.new
<   @@final = lambda {|id|
<     @@mutex.synchronize {
<       rids = @@id_map[id]
<       if rids
< 	for rid in rids
< 	  @@id_rev_map.delete(rid)
< 	end
< 	@@id_map.delete(id)
---
>   @@monitor = Monitor.new
> 
>   @@object_finalizer = lambda do |id|
>     rids = @@id_map.delete(id)
>     if rids
>       rids.each do |rid|
>         @@id_rev_map.delete(rid)
>       end
>     end
>   end
>   
>   @@reference_finalizer = lambda do |id|
>     rid = @@id_rev_map.delete(id)
>     if rid
>       obj = ObjectSpace._id2ref(referenced_object_id) rescue nil
>       if obj
>         backreferences = obj.instance_variable_get(:@__weak_backreferences__) if obj.instance_variable_defined?(:@__weak_backreferences__)
>         if backreferences
>           backreferences.delete(object_id)
>           obj.send(:remove_instance_variable, :@__weak_backreferences__) if backreferences.empty?
>         end
32,36c44,47
<       rid = @@id_rev_map[id]
<       if rid
< 	@@id_rev_map.delete(id)
< 	@@id_map[rid].delete(id)
< 	@@id_map.delete(rid) if @@id_map[rid].empty?
---
>       refs = @@id_map[rid]
>       if refs
>         refs.delete(id)
>         @@id_map.delete(rid) if refs.empty?
38,39c49,50
<     }
<   }
---
>     end
>   end
42,45c53,56
<     @__id = orig.object_id
<     ObjectSpace.define_finalizer orig, @@final
<     ObjectSpace.define_finalizer self, @@final
<     @@mutex.synchronize {
---
>     @__id = orig.__id__
>     ObjectSpace.define_finalizer orig, @@object_finalizer
>     ObjectSpace.define_finalizer self, @@reference_finalizer
>     @@monitor.synchronize do
47,49c58,61
<     }
<     @@id_map[@__id].push self.object_id
<     @@id_rev_map[self.object_id] = @__id
---
>       @@id_map[@__id].push self.__id__
>       @@id_rev_map[__id__] = @__id
>       __add_weakref_backreference__(orig)
>     end
54,56c66
<     unless @@id_rev_map[self.object_id] == @__id
<       Kernel::raise RefError, "Invalid Reference - probably recycled", Kernel::caller(2)
<     end
---
>     obj = nil
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<       ObjectSpace._id2ref(@__id)
---
>       if @@id_rev_map[self.__id__] == @__id
>         obj = ObjectSpace._id2ref(@__id)
>         obj = nil unless __verify_weakref_backreference__(obj)
>       end
60c73
<       Kernel::raise RefError, "Invalid Reference - probably recycled", Kernel::caller(2)
---
>       # Object has been garbage collected.
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>     Kernel::raise(RefError, "Invalid Reference - probably recycled", Kernel::caller(1)) unless obj
>     obj
62a78
>   
67c83,90
<     @@id_rev_map[self.object_id] == @__id
---
>     if @@id_rev_map[self.__id__] == @__id
>       obj = ObjectSpace._id2ref(@__id)
>       __verify_weakref_backreference__(obj)
>     else
>       false
>     end
>   rescue RangeError
>     false
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>   
>   private
> 
>     # Add a backreference to the weakref object id in the referenced object to protect
>     # against the object id being recycled before the finalizers have a chance to run.
>     def __add_weakref_backreference__(obj)
>       backreferences = obj.instance_variable_get(:@__weak_backreferences__) if obj.instance_variable_defined?(:@__weak_backreferences__)
>       unless backreferences
>         backreferences = []
>         obj.instance_variable_set(:@__weak_backreferences__, backreferences)
>       end
>       backreferences << object_id
>     end
> 
>     # Verify that the object is the one the weakref thinks it is. On runtimes where
>     # object ids are recycled after garbage collection and reallocated to new objects,
>     # there is a chance that the reference could find an object at the specified
>     # location in the ObjectSpace that is not the one it originally referenced.
>     def __verify_weakref_backreference__(obj)
>       backreferences = obj.instance_variable_get(:@__weak_backreferences__) if obj.instance_variable_defined?(:@__weak_backreferences__)
>       backreferences && backreferences.include?(self.__id__)
>     end
72c117
< #  require 'thread'
---
>   #  require 'thread'