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 Persistent 
 25  from Globals import DTMLFile 
 26  from AccessControl import ClassSecurityInfo 
 27   
 28  from OFS.SimpleItem import SimpleItem 
 29   
 30 -class PObjectCache(SimpleItem): 
 31      editCache = DTMLFile('dtml/editCache', globals()) 
 32      manage_options = ({'label':'Cache','action':'editCache'},) 
 33   
 34      security = ClassSecurityInfo() 
 35   
 36 -    def __init__(self, id, timeout=20, clearthresh=20): 
 37          self.id = id 
 38          self.timeout = timeout 
 39          self.clearcount = self.clearthresh = clearthresh 
 40          self.cache = {} 
 41   
 42       
 43 -    def checkCache(self, key): 
 44          """check to see if key is in cache return None if not""" 
 45          if self.cache.has_key(key): 
 46              cobj = self.cache[key] 
 47              if cobj.checkTime():  
 48                  return cobj.getObj() 
 49              else: 
 50                  del self.cache[key] 
 51                  self._p_changed = 1 
 52          return None 
 53   
 54   
 55 -    def addToCache(self, key, obj): 
 56          """add an object to the cache""" 
 57          cobj = CacheObj(obj, self.timeout) 
 58          self.cache[key] = cobj 
 59   
 60 -    def manage_clearCache(self, REQUEST=None): 
 61          self.cleanCache(force=1) 
 62          if REQUEST: 
 63              return self.editCache(self, REQUEST, "cleared cache")  
 64   
 65           
 66 -    def cleanCache(self, force=0): 
 67          """clean the cache if nessesary""" 
 68          cleared = 0 
 69          if self.cache: 
 70              self.clearcount -= 1 
 71              if force or self.clearcount < self.clearthresh: 
 72                  for key, value in self.cache.items(): 
 73                      if not value.checkTime(): 
 74                          cleared = 1 
 75                          del self.cache[key] 
 76                  self.clearcount = self.clearthresh 
 77          return cleared 
 78   
 79   
 80 -    def getCache(self): 
 81          return self.cache 
 82   
 83   
 84      security.declareProtected('View','getCacheTimeout') 
 85 -    def getCacheTimeout(self): 
 86          """return cache timeout""" 
 87          return self.timeout 
 88   
 89   
 90      security.declareProtected('View','getCacheClearthresh') 
 91 -    def getCacheClearthresh(self): 
 92          """return cache clearthresh""" 
 93          return self.clearthresh 
 94   
 95   
 96 -class CacheObj: 
 97       
 98 -    def __init__(self, obj, timeout): 
 99          self._obj = obj 
100          self._timeout = timeout 
101          self._time = time.time() 
102   
103 -    def checkTime(self): 
104          if self._time + self._timeout < time.time(): 
105              return 0 
106          else: 
107              return 1   
108       
109 -    def getObj(self): 
110          return self._obj 
111   
112 -    def getTime(self): 
113          """Return the time at which this cache object was created""" 
114          return self._time 
115