49 lines
711 B
Ruby
49 lines
711 B
Ruby
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class File
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def exclusive_lock
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flock File::LOCK_EX
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end
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def shared_lock
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flock File::LOCK_SH
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end
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def unblock
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flock File::LOCK_UN
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end
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end
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class FileQueue
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attr_reader :file, :size
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alias to_io file
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def initialize file, size = 16
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@file = case file
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when File then file
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else File.open file, 'a+'
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end
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@size, @pack = size, "A#{size}"
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end
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def push *a
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f = @file
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f.seek 0, IO::SEEK_END
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f.exclusive_lock
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f.write a.pack( @pack*a.length)
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f.unblock
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end
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def pop
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f = @file
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f.rewind
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f.exclusive_lock
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s = f.read( @size).unpack( 'L')[0]
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f.rewind
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f.write [s.succ].pack( 'L')
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f.sync
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f.shared_lock
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f.pos = s
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f.read( @size).unpack( 'L')[0]
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f.unblock
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end
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end
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