Source Code for Module ZenUtils.PObjectCache

  1  ########################################################################### 
  2  # 
  3  # This program is part of Zenoss Core, an open source monitoring platform. 
  4  # Copyright (C) 2007, Zenoss Inc. 
  5  # 
  6  # This program is free software; you can redistribute it and/or modify it 
  7  # under the terms of the GNU General Public License version 2 as published by 
  8  # the Free Software Foundation. 
  9  # 
 10  # For complete information please visit: http://www.zenoss.com/oss/ 
 11  # 
 12  ########################################################################### 
 13   
 14  """PObjectCache 
 15   
 16  Persistent object cache that should be placed in a temp_folder 
 17   
 18  $Id: PObjectCache.py,v 1.2 2003/04/11 15:50:18 edahl Exp $""" 
 19   
 20  __version__ = "$Revision: 1.2 $"[11:-2] 
 21   
 22  import time 
 23   
 24  from Globals import DTMLFile 
 25  from AccessControl import ClassSecurityInfo 
 26   
 27  from OFS.SimpleItem import SimpleItem 
 28   
 29 -class PObjectCache(SimpleItem): 
 30      editCache = DTMLFile('dtml/editCache', globals()) 
 31      manage_options = ({'label':'Cache','action':'editCache'},) 
 32   
 33      security = ClassSecurityInfo() 
 34   
 35 -    def __init__(self, id, timeout=20, clearthresh=20): 
 36          self.id = id 
 37          self.timeout = timeout 
 38          self.clearcount = self.clearthresh = clearthresh 
 39          self.cache = {} 
 40   
 41       
 42 -    def checkCache(self, key): 
 43          """check to see if key is in cache return None if not""" 
 44          if self.cache.has_key(key): 
 45              cobj = self.cache[key] 
 46              if cobj.checkTime():  
 47                  return cobj.getObj() 
 48              else: 
 49                  del self.cache[key] 
 50                  self._p_changed = 1 
 51          return None 
 52   
 53   
 54 -    def addToCache(self, key, obj): 
 55          """add an object to the cache""" 
 56          cobj = CacheObj(obj, self.timeout) 
 57          self.cache[key] = cobj 
 58   
 59 -    def manage_clearCache(self, REQUEST=None): 
 60          self.cleanCache(force=1) 
 61          if REQUEST: 
 62              return self.editCache(self, REQUEST, "cleared cache")  
 63   
 64           
 65 -    def cleanCache(self, force=0): 
 66          """clean the cache if nessesary""" 
 67          cleared = 0 
 68          if self.cache: 
 69              self.clearcount -= 1 
 70              if force or self.clearcount < self.clearthresh: 
 71                  for key, value in self.cache.items(): 
 72                      if not value.checkTime(): 
 73                          cleared = 1 
 74                          del self.cache[key] 
 75                  self.clearcount = self.clearthresh 
 76          return cleared 
 77   
 78   
 79 -    def getCache(self): 
 80          return self.cache 
 81   
 82   
 83      security.declareProtected('View','getCacheTimeout') 
 84 -    def getCacheTimeout(self): 
 85          """return cache timeout""" 
 86          return self.timeout 
 87   
 88   
 89      security.declareProtected('View','getCacheClearthresh') 
 90 -    def getCacheClearthresh(self): 
 91          """return cache clearthresh""" 
 92          return self.clearthresh 
 93   
 94   
 95 -class CacheObj: 
 96       
 97 -    def __init__(self, obj, timeout): 
 98          self._obj = obj 
 99          self._timeout = timeout 
100          self._time = time.time() 
101   
102 -    def checkTime(self): 
103          if self._time + self._timeout < time.time(): 
104              return 0 
105          else: 
106              return 1   
107       
108 -    def getObj(self): 
109          return self._obj 
110   
111 -    def getTime(self): 
112          """Return the time at which this cache object was created""" 
113          return self._time 
114