Class: Mongrel::Stats

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name) ⇒ Stats

Returns a new instance of Stats.


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

def initialize(name)
  @name = name
  reset
end

Instance Attribute Details

#maxObject (readonly)

Returns the value of attribute max


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

def max
  @max
end

#minObject (readonly)

Returns the value of attribute min


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

def min
  @min
end

#nObject (readonly)

Returns the value of attribute n


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

def n
  @n
end

#sumObject (readonly)

Returns the value of attribute sum


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

def sum
  @sum
end

#sumsqObject (readonly)

Returns the value of attribute sumsq


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

def sumsq
  @sumsq
end

Instance Method Details

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

Dump this Stats object with an optional additional message.


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

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

#meanObject

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


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# File 'lib/mongrel/stats.rb', line 59

def mean
  @sum / @n
end

#resetObject

Resets the internal counters so you can start sampling again.


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# File 'lib/mongrel/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/mongrel/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

#sdObject

Calculates the standard deviation of the data so far.


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

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

#tickObject

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

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# File 'lib/mongrel/stats.rb', line 83

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

#to_sObject

Returns a common display (used by dump)


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

def to_s  
"[#{@name}]: SUM=%0.4f, SUMSQ=%0.4f, N=%0.4f, MEAN=%0.4f, SD=%0.4f, MIN=%0.4f, MAX=%0.4f" % [@sum, @sumsq, @n, mean, sd, @min, @max]
end