Viewing file:  failover.py (3.29 KB) -rw-r--r--
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#!/usr/bin/python
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Library General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
# Copyright 2003 Jack Neely, NC State University
# Here we define a base class for failover methods. The idea here is that each
# failover method uses a class derived from the base class so yum only has to
# worry about calling get_serverurl() and server_failed() and these classes will
# figure out which URL to cough up based on the failover method.
import random
class baseFailOverMethod:
def __init__(self, repo):
self.repo = repo
self.failures = 0
def get_serverurl(self, i=None):
"""Returns a serverurl based on this failover method or None
if complete failure. If i is given it is a direct index
to pull a server URL from instead of using the failures
counter."""
return None
def server_failed(self):
"Tells the failover method that the current server is failed."
self.failures = self.failures + 1
def reset(self, i=0):
"Reset the failures counter to a given index."
self.failures = i
def get_index(self):
"""Returns the current number of failures which is also the
index into the list this object represents. ger_serverurl()
should always be used to translate an index into a URL
as this object may change how indexs map. (See RoundRobin)"""
return self.failures
def len(self):
"""Returns the how many URLs we've got to cycle through."""
return len(self.repo.urls)
class priority(baseFailOverMethod):
"""Chooses server based on the first success in the list."""
def get_serverurl(self, i=None):
"Returns a serverurl based on this failover method or None if complete failure."
if i == None:
index = self.failures
else:
index = i
if index >= len(self.repo.urls):
return None
return self.repo.urls[index]
class roundRobin(baseFailOverMethod):
"""Chooses server based on a round robin."""
def __init__(self, repo):
baseFailOverMethod.__init__(self, repo)
random.seed()
self.offset = random.randint(0, 37)
def get_serverurl(self, i=None):
"Returns a serverurl based on this failover method or None if complete failure."
if i == None:
index = self.failures
else:
index = i
if index >= len(self.repo.urls):
return None
rr = (index + self.offset) % len(self.repo.urls)
return self.repo.urls[rr]
# SDG
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