class ChecksumTesting
    require 'digest/md5'
    require 'benchmark'
 
    def benchmark(label)
        seconds = Benchmark.realtime { yield }
        puts "%s in %0.2f seconds" % [label, seconds]
    end
 
    def initialize(file)
        @filename = file
    end
 
    def run
        [512, 1024, 1024*1024].each do |size|
            benchmark("Buffer size %s" % size) do
                5.times { md5(size) }
            end
        end
 
        benchmark("External md5") do
            5.times { test_external }
        end
    end
 
    def test_large
        md5(1024*1024*1024)
    end
 
    def test_small
        md5(512)
    end
 
    def test_external
        output = %x{md5sum #{@filename}}
    end
 
    private
 
    def md5(buffer)
        digest = Digest::MD5.new()
        File.open(@filename, 'r') do |file|
            while content = file.read(buffer)
                digest << content
            end
        end
 
        return digest.hexdigest
    end
end