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def find key, before_list, after_list
retry_tag = Class.new Exception
begin
pp = nil
p = @head
@level_max.downto(0){|level|
pp = p.links[level].get_link
loop {
ppp, mark = pp.links[level].get
while mark do
snip = p.links[level].compare_and_set pp, ppp,
false, false
unless snip then
raise retry_tag
end
pp = ppp
ppp, mark = pp.links[level].get
end
if pp.key.send(@cmp_op, key) == -1 then
p = pp
pp = ppp
else
break
end
}
before_list[level] = p
after_list[level] = pp
}
if pp.key.send(@cmp_op, key) == 0 then
pp
else
nil
end
rescue retry_tag
retry
end
end
private :find
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loop {|tag|
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}
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