From: Eric Mahurin <eric.mahurin@...>
Date: 2008-02-04T01:40:37+09:00
Subject: Re: [QUIZ] Parsing JSON (#155)

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On Feb 1, 2008 11:30 AM, ara howard <ara.t.howard@gmail.com> wrote:

>
> On Feb 1, 2008, at 9:09 AM, Eric Mahurin wrote:
>
> >   Maybe just have a little ruby
> > script that generates a stream of repeatable random (but valid) JSON.
>
> cfp2:~ > cat a.rb
> require 'rubygems'
> require 'json'
>

The benchmark below has no gem dependencies, generates tests with deep
structures, and has self-checking.  It found a bug that the original unit
tested didn't.  By default, this benchmark keeps increasing the depth until
the runtime is >= 1s.

Also, I made some wrappers for the json and fjson gems to see how they
perform.  Here are the results on my machine:

fjson: 224823 chars/second
json(pure): 220289 chars/second
json(ext): 1522250 chars/second

require 'benchmark'

class RandomJSON
    def initialize(value=0)
        @number = -1
        @string = -1
        @boolean = -1
        @constant = -1
        @value = value-1
    end
    def number
        case (@number=(@number+1)%3)
        when 0 : 0
        when 1 : 1234
        when 2 : 3.75e+1
        end
    end
    def string
        case (@string=(@string+1)%3)
        when 0 : ""
        when 1 : "JSON"
        when 2 : "\"\\\/\b\f\r\t"
        end
    end
    def boolean
        case (@boolean=(@boolean+1)%3)
        when 0 : false
        when 1 : true
        when 2 : nil
        end
    end
    def constant
        case (@constant=(@constant+1)%3)
        when 0 : number
        when 1 : string
        when 2 : boolean
        end
    end
    def array(depth)
        a = []
        depth.times {
            a << value(depth-1)
        }
        a
    end
    def object(depth)
        o = {}
        depth.times {
            o[string] = value(depth-1)
        }
        o
    end
    def value(depth, v=nil)
        case (v||(@value=(@value+1)%3))
        when 0 : array(depth)
        when 1 : object(depth)
        else constant
        end
    end
end

generator = RandomJSON.new((ARGV[1]||0).to_i)

parser = JSONParser.new
Benchmark.bm { |b|
    l = nil; t = nil
    13.times { |depth|
        tree = generator.value(depth, depth%2)
        s = tree.inspect
        #puts s
        s.gsub!(/=>/, ':')
        s.gsub!(/nil/, 'null')
        tree2 = nil
        #puts s
        l = s.length
        t = b.report("#{depth} #{l}") { tree2 = parser.parse(s) }
        raise if tree2!=tree
        break if (t.real>=(ARGV[0]||1).to_f)
    }
    puts "#{(l/t.real).to_i} chars/second"
}

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