ruby Pico dabase , ACID

datatase.rb

def sql 
  fn="rdb.db"
  if defined?($data)
    ( yield( a=Marshal.load(Marshal.dump($data)) ) ;
      $data=a ; File.open(fn,"rb+") { |f| Marshal.dump($data,f) }
    ) rescue p $!
    return
  end
  File.exists?(fn) || File.write(fn,"")
  File.open(fn,"rb+") do |f|
    data= File.size(fn)>0 ? Marshal.load(f) : {}
    f.rewind
    begin
      yield(data)
      $data=data
      Marshal.dump($data,f) 
    rescue Exception => e
      p $!
    end
  end
end


sql { |db| db[:table1]=(0..1000).map {|i| {id: i, body:""} } unless db[:table1] }

22.upto(25) { |i| sql { |db| p db[:table1][i][:body]="Hello #{i}" } }
sql { |db| p db[:table1][23] }

sql { |db|  db[:table1][23]={junk:[]} ; raise("error") }
sql { |db| p db[:table1][23] }
sql { |db| p db[:table1].select {|rec| rec[:id]%343==0 } }