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# Weak Reference class that does not bother GCing.
#
# Usage:
# foo = Object.new
# foo = Object.new
# p foo.to_s # original's class
# foo = WeakRef.new(foo)
# p foo.to_s # should be same class
# ObjectSpace.garbage_collect
# p foo.to_s # should raise exception (recycled)
require "delegate"
class WeakRef<Delegator
class RefError<StandardError
end
ID_MAP = {} # obj -> [ref,...]
ID_REV_MAP = {} # ref -> obj
ObjectSpace.add_finalizer(lambda{|id|
rids = ID_MAP[id]
if rids
for rid in rids
ID_REV_MAP[rid] = nil
end
ID_MAP[id] = nil
end
rid = ID_REV_MAP[id]
if rid
ID_REV_MAP[id] = nil
ID_MAP[rid].delete(id)
ID_MAP[rid] = nil if ID_MAP[rid].empty?
end
})
def initialize(orig)
super
@__id = orig.__id__
ObjectSpace.call_finalizer orig
ObjectSpace.call_finalizer self
ID_MAP[@__id] = [] unless ID_MAP[@__id]
ID_MAP[@__id].push self.__id__
ID_REV_MAP[self.id] = @__id
end
def __getobj__
unless ID_MAP[@__id]
raise RefError, "Illegal Reference - probably recycled", caller(2)
end
ObjectSpace._id2ref(@__id)
end
def weakref_alive?
if ID_MAP[@__id]
true
else
false
end
end
def []
__getobj__
end
end
if __FILE__ == $0
require 'thread'
foo = Object.new
p foo.to_s # original's class
foo = WeakRef.new(foo)
p foo.to_s # should be same class
ObjectSpace.garbage_collect
p foo.to_s # should raise exception (recycled)
end
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