require "delegate"
class WeakRef<Delegator
class RefError<StandardError
end
@@id_map = {} @@id_rev_map = {} @@final = lambda{|id|
__old_status = Thread.critical
Thread.critical = true
begin
rids = @@id_map[id]
if rids
for rid in rids
@@id_rev_map.delete(rid)
end
@@id_map.delete(id)
end
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?
end
ensure
Thread.critical = __old_status
end
}
def initialize(orig)
super
__setobj__(orig)
end
def __getobj__
unless @@id_rev_map[self.__id__] == @__id
raise RefError, "Illegal Reference - probably recycled", caller(2)
end
begin
ObjectSpace._id2ref(@__id)
rescue RangeError
raise RefError, "Illegal Reference - probably recycled", caller(2)
end
end
def __setobj__(obj)
@__id = obj.__id__
__old_status = Thread.critical
begin
Thread.critical = true
unless @@id_rev_map.key?(self)
ObjectSpace.define_finalizer obj, @@final
ObjectSpace.define_finalizer self, @@final
end
@@id_map[@__id] = [] unless @@id_map[@__id]
ensure
Thread.critical = __old_status
end
@@id_map[@__id].push self.__id__
@@id_rev_map[self.__id__] = @__id
end
def weakref_alive?
@@id_rev_map[self.__id__] == @__id
end
end
if __FILE__ == $0
require 'thread'
foo = Object.new
p foo.to_s foo = WeakRef.new(foo)
p foo.to_s ObjectSpace.garbage_collect
p foo.to_s end