Class: Mongrel::Stats

### Home Classes Methods

### In Files

- lib/mongrel/stats.rb

### Parent

Object

### Methods

- ::new
- #dump
- #mean
- #reset
- #sample
- #sd
- #tick
- #to_s

### Files

- CHANGELOG
- COPYING
- LICENSE
- README
- Makefile

### Class/Module Index

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No matching classes.

# Mongrel::Stats

### Attributes

max[R]
min[R]
n[R]
sum[R]
sumsq[R]

### Public Class Methods

new(name) click to toggle source

    # File lib/mongrel/stats.rb, line 19
    def initialize(name)
      @name = name
      reset
    end

### Public Instance Methods

dump(msg = "", out=STDERR) click to toggle source

Dump this Stats object with an optional additional message.

    # File lib/mongrel/stats.rb, line 48
    def dump(msg = "", out=STDERR)
      out.puts "#{msg}: #{self.to_s}"
    end

mean() click to toggle source

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

    # File lib/mongrel/stats.rb, line 59
    def mean
      @sum / @n
    end

reset() click to toggle source

Resets the internal counters so you can start sampling again.

    # 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) click to toggle source

Adds a sampling to the calculations.

    # 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

sd() click to toggle source

Calculates the standard deviation of the data so far.

    # 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

tick() click to toggle source

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")

    # File lib/mongrel/stats.rb, line 83
    def tick
      now = Time.now
      sample(now - @last_time)
      @last_time = now
    end

to_s() click to toggle source

Returns a common display (used by dump)

    # 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

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