Class: RFuzz::Sampler

Inherits:
Object
  • Object
show all
Defined in:
lib/rfuzz/stats.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name) ⇒ Sampler

Returns a new instance of Sampler.



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# File 'lib/rfuzz/stats.rb', line 19

def initialize(name)
  @name = name
  reset
end

Instance Attribute Details

#max ⇒ Object (readonly)

Returns the value of attribute max.



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# File 'lib/rfuzz/stats.rb', line 17

def max
  @max
end

#min ⇒ Object (readonly)

Returns the value of attribute min.



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# File 'lib/rfuzz/stats.rb', line 17

def min
  @min
end

#n ⇒ Object (readonly)

Returns the value of attribute n.



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# File 'lib/rfuzz/stats.rb', line 17

def n
  @n
end

#sum ⇒ Object (readonly)

Returns the value of attribute sum.



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# File 'lib/rfuzz/stats.rb', line 17

def sum
  @sum
end

#sumsq ⇒ Object (readonly)

Returns the value of attribute sumsq.



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# File 'lib/rfuzz/stats.rb', line 17

def sumsq
  @sumsq
end

Class Method Details

.keys ⇒ Object

Class method that returns the headers that a CSV file would have for the values that this stats object is using.



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# File 'lib/rfuzz/stats.rb', line 64

def self.keys
  ["name","sum","sumsq","n","mean","sd","min","max"]
end

Instance Method Details

#dump(msg = "", out = STDERR) ⇒ Object

Dump this Sampler object with an optional additional message.



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# File 'lib/rfuzz/stats.rb', line 48

def dump(msg = "", out=STDERR)
  out.puts "#{msg}: #{self.to_s}"
end

#mark ⇒ Object

You can just call tick repeatedly if you need the delta times between a set of sample periods, but many times you actually want to sample how long something takes between a start/end period. Call mark at the beginning and then tick at the end you’ll get this kind of measurement. Don’t mix mark/tick and tick sampling together or the measurement will be meaningless.



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# File 'lib/rfuzz/stats.rb', line 94

def mark
  @last_time = Time.now
end

#mean ⇒ Object

Calculates and returns the mean for the data passed so far.



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# File 'lib/rfuzz/stats.rb', line 74

def mean
  @sum / @n
end

#reset ⇒ Object

Resets the internal counters so you can start sampling again.



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# File 'lib/rfuzz/stats.rb', line 25

def reset
  @sum = 0.0
  @sumsq = 0.0
  @last_time = Time.new
  @n = 0.0
  @min = 0.0
  @max = 0.0
end

#sample(s) ⇒ Object

Adds a sampling to the calculations.



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# File 'lib/rfuzz/stats.rb', line 35

def sample(s)
  @sum += s
  @sumsq += s * s
  if @n == 0
    @min = @max = s
  else
    @min = s if @min > s
    @max = s if @max < s
  end
  @n+=1
end

#sd ⇒ Object

Calculates the standard deviation of the data so far.



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# File 'lib/rfuzz/stats.rb', line 79

def sd
  # (sqrt( ((s).sumsq - ( (s).sum * (s).sum / (s).n)) / ((s).n-1) ))
  begin
    return Math.sqrt( (@sumsq - ( @sum * @sum / @n)) / (@n-1) )
  rescue Errno::EDOM
    return 0.0
  end
end

#tick ⇒ Object

Adds a time delta between now and the last time you called this. This will give you the average time between two activities.

An example is:

t = Sampler.new("do_stuff")
10000.times { do_stuff(); t.tick }
t.dump("time")



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# File 'lib/rfuzz/stats.rb', line 107

def tick
  now = Time.now
  sample(now - @last_time)
  @last_time = now
end

#to_hash ⇒ Object 



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# File 'lib/rfuzz/stats.rb', line 68

def to_hash
  {"name" => @name, "sum" => @sum, "sumsq" => @sumsq, "mean" => mean,
    "sd" => sd, "min" => @min, "max" => @max}
end

#to_s ⇒ Object

Returns a common display (used by dump)



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# File 'lib/rfuzz/stats.rb', line 53

def to_s  
"[%s]: SUM=%0.6f, SUMSQ=%0.6f, N=%0.6f, MEAN=%0.6f, SD=%0.6f, MIN=%0.6f, MAX=%0.6f" % values
end

#values ⇒ Object

An array of the values minus the name: [sum,sumsq,n,mean,sd,min,max]



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# File 'lib/rfuzz/stats.rb', line 58

def values
  [@name, @sum, @sumsq, @n, mean, sd, @min, @max]
end