shinken/load.py

   1 #!/usr/bin/env python
   2 #Copyright (C) 2009-2010 :
   3 #    Gabes Jean, naparuba@gmail.com
   4 #    Gerhard Lausser, Gerhard.Lausser@consol.de
   5 #    Gregory Starck, g.starck@gmail.com
   6 #
   7 #This file is part of Shinken.
   8 #
   9 #Shinken is free software: you can redistribute it and/or modify
  10 #it under the terms of the GNU Affero General Public License as published by
  11 #the Free Software Foundation, either version 3 of the License, or
  12 #(at your option) any later version.
  13 #
  14 #Shinken is distributed in the hope that it will be useful,
  15 #but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 #MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 #GNU Affero General Public License for more details.
  18 #
  19 #You should have received a copy of the GNU Affero General Public License
  20 #along with Shinken.  If not, see <http://www.gnu.org/licenses/>.
  21
  22
  23
  24 import time, math
  25 #EXP_1=1/math.exp(5/60.0)
  26 #EXP_5=1/math.exp(5/(5*60.0))
  27 #EXP_15=1/math.exp(5/(15*60.0))
  28
  29 #From advance load average's code (another of my projects :) )
  30 #def calc_load_load(load, exp,n):
  31 #        load = n + exp*(load - n)
  32 #        return (load, exp)
  33
  34
  35 #This class if for having a easy Load calculation
  36 #without having to send value at regular interval
  37 #(but it's more efficient if you do this :) ) and not
  38 #having a list and all. Just an object, an update and a get
  39 #You can define m : the average is for m minutes. The val is
  40 #the initial value. It's better if it's 0 but you can choice.
  41
  42
  43 class Load:
  44     #m = number of minutes for the average
  45     #val = initial_value
  46     def __init__(self, m=1, initial_value=0):
  47         self.exp = 0 #first exp
  48         self.m = m #Number of minute of the avg
  49         self.last_update = 0 #last update of the value
  50         self.val = initial_value #first value
  51
  52
  53     def update_load(self, new_val):
  54         #The first call do not change the value, just tag
  55         #the begining of last_update
  56         if self.last_update == 0:
  57             self.last_update = time.time()
  58             return
  59         now = time.time()
  60         try:
  61             diff = now - self.last_update
  62             self.exp = 1/math.exp(diff/ (self.m*60.0))
  63             self.val = new_val + self.exp*(self.val - new_val)
  64             self.last_update = now
  65         except OverflowError: #if the time change without notice, we overflow :(
  66             pass
  67         except ZeroDivisionError: #do not care
  68             pass
  69
  70
  71     def get_load(self):
  72         return self.val
  73
  74
  75 if __name__ == '__main__':
  76     l = Load()
  77     t = time.time()
  78     for i in xrange(1, 300):
  79         l.update_load(1)
  80         print '[', int(time.time() - t), ']', l.get_load(), l.exp
  81         time.sleep(5)