Source Code for Module yum.failover

  1  #!/usr/bin/python 
  2  # This program is free software; you can redistribute it and/or modify 
  3  # it under the terms of the GNU General Public License as published by 
  4  # the Free Software Foundation; either version 2 of the License, or 
  5  # (at your option) any later version. 
  6  # 
  7  # This program is distributed in the hope that it will be useful, 
  8  # but WITHOUT ANY WARRANTY; without even the implied warranty of 
  9  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 10  # GNU Library General Public License for more details. 
 11  # 
 12  # You should have received a copy of the GNU General Public License 
 13  # along with this program; if not, write to the Free Software 
 14  # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 
 15  # Copyright 2003 Jack Neely, NC State University 
 16   
 17  # Here we define a base class for failover methods.  The idea here is that each 
 18  # failover method uses a class derived from the base class so yum only has to 
 19  # worry about calling get_serverurl() and server_failed() and these classes will  
 20  # figure out which URL to cough up based on the failover method. 
 21   
 22  import random 
 23   
 24 -class baseFailOverMethod: 
 25   
 26 -    def __init__(self, repo): 
 27          self.repo = repo 
 28          self.failures = 0 
 29       
 30 -    def get_serverurl(self, i=None): 
 31          """Returns a serverurl based on this failover method or None  
 32             if complete failure.  If i is given it is a direct index 
 33             to pull a server URL from instead of using the failures  
 34             counter.""" 
 35          return None 
 36           
 37 -    def server_failed(self): 
 38          "Tells the failover method that the current server is failed." 
 39          self.failures = self.failures + 1 
 40           
 41 -    def reset(self, i=0): 
 42          "Reset the failures counter to a given index." 
 43          self.failures = i 
 44   
 45 -    def get_index(self): 
 46          """Returns the current number of failures which is also the 
 47             index into the list this object represents.  ger_serverurl() 
 48             should always be used to translate an index into a URL 
 49             as this object may change how indexs map.  (See RoundRobin)""" 
 50   
 51          return self.failures 
 52      
 53 -    def len(self): 
 54          """Returns the how many URLs we've got to cycle through.""" 
 55   
 56          return len(self.repo.urls) 
 57           
 58               
 59   
 60 -class priority(baseFailOverMethod): 
 61   
 62      """Chooses server based on the first success in the list.""" 
 63       
 64 -    def get_serverurl(self, i=None): 
 65          "Returns a serverurl based on this failover method or None if complete failure." 
 66           
 67          if i == None: 
 68              index = self.failures 
 69          else: 
 70              index = i 
 71           
 72          if index >= len(self.repo.urls): 
 73              return None 
 74           
 75          return self.repo.urls[index] 
 76           
 77           
 78       
 79 -class roundRobin(baseFailOverMethod): 
 80   
 81      """Chooses server based on a round robin.""" 
 82       
 83 -    def __init__(self, repo): 
 84          baseFailOverMethod.__init__(self, repo) 
 85          random.seed() 
 86          self.offset = random.randint(0, 37) 
 87       
 88 -    def get_serverurl(self, i=None): 
 89          "Returns a serverurl based on this failover method or None if complete failure." 
 90   
 91          if i == None: 
 92              index = self.failures 
 93          else: 
 94              index = i 
 95           
 96          if index >= len(self.repo.urls): 
 97              return None 
 98           
 99          rr = (index + self.offset) % len(self.repo.urls) 
100          return self.repo.urls[rr]    
101   
102  # SDG 
103