トランザクションシミュレータ - Qiita

class Command end class Begin < Command end class Rollback < Command end class Commit < Command end class Read < Command attr_reader :var def initialize(var) @var = var end end class Write < Command attr_reader :var,:val def initialize(var,val) @var = var @val = val end end class Lock attr_reader :tr,:var,:type def initialize(tr,var,type) @tr=tr @var=var @type=type end end class Unlock attr_reader