Source Code for Module Products.ZenUtils.ObjectCache

  1  ############################################################################## 
  2  #  
  3  # Copyright (C) Zenoss, Inc. 2007, all rights reserved. 
  4  #  
  5  # This content is made available according to terms specified in 
  6  # License.zenoss under the directory where your Zenoss product is installed. 
  7  #  
  8  ############################################################################## 
  9   
 10   
 11  """NcoProduct 
 12   
 13  Data connector for Micromuse Omnibus 
 14   
 15  $Id: ObjectCache.py,v 1.7 2003/04/14 21:08:25 edahl Exp $""" 
 16   
 17  __version__ = "$Revision: 1.7 $"[11:-2] 
 18   
 19  from Globals import Persistent 
 20  from Globals import DTMLFile 
 21  from AccessControl import ClassSecurityInfo 
 22  import time 
 23   
 24 -class ObjectCache(Persistent): 
 25      editCache = DTMLFile('dtml/editCache', globals()) 
 26      manage_options = ({'label':'Cache','action':'editCache'},) 
 27   
 28      security = ClassSecurityInfo() 
 29   
 30 -    def __init__(self, timeout=20, clearthresh=20): 
 31          self.timeout = timeout 
 32          self.clearthresh = clearthresh 
 33   
 34 -    def initCache(self): 
 35          """make sure that volitile attributes exist""" 
 36          if not hasattr(self, '_v_cache'): 
 37              self._v_cache = {} 
 38          if not hasattr(self, '_v_clearcount'): 
 39              self._v_clearcount = self.clearthresh 
 40   
 41 -    def checkCache(self, key): 
 42          """check to see if key is in cache return None if not""" 
 43          self.initCache() 
 44          if key in self._v_cache: 
 45              cobj = self._v_cache[key] 
 46              if cobj.checkTime():  
 47                  return cobj.getObj() 
 48              else: 
 49                  del self._v_cache[key] 
 50          return None 
 51   
 52   
 53 -    def addToCache(self, key, obj): 
 54          """add an object to the cache""" 
 55          self.initCache() 
 56          cobj = CacheObj(obj, self.timeout) 
 57          self._v_cache[key] = cobj 
 58   
 59   
 60 -    def clearCache(self, key=None): 
 61          """Clear the cache. 
 62          """ 
 63          self.initCache() 
 64          if key is not None: 
 65              try: 
 66                  del self._v_cache[key] 
 67              except KeyError: 
 68                  pass 
 69          else: 
 70              self._v_cache = {} 
 71   
 72   
 73 -    def cleanCache(self, force=0): 
 74          """clean the cache if nessesary""" 
 75          self.initCache() 
 76          cleared = 0 
 77          if self._v_cache: 
 78              self._v_clearcount -= 1 
 79              if force or self._v_clearcount < self.clearthresh: 
 80                  for key, value in self._v_cache.items(): 
 81                      if not value.checkTime(): 
 82                          cleared = 1 
 83                          del self._v_cache[key] 
 84                  self._v_clearcount = self.clearthresh 
 85          return cleared 
 86           
 87 -    def getCache(self): 
 88          self.initCache() 
 89          return self._v_cache 
 90   
 91      security.declareProtected('View','getCacheTimeout') 
 92 -    def getCacheTimeout(self): 
 93          """return cache timeout""" 
 94          return self.timeout 
 95   
 96      security.declareProtected('View','getCacheClearthresh') 
 97 -    def getCacheClearthresh(self): 
 98          """return cache clearthresh""" 
 99          return self.clearthresh 
100   
101 -class CacheObj: 
102       
103 -    def __init__(self, obj, timeout): 
104          self._obj = obj 
105          self._timeout = timeout 
106          self._time = time.time() 
107   
108 -    def checkTime(self): 
109          if self._time + self._timeout < time.time(): 
110              return 0 
111          else: 
112              return 1   
113       
114 -    def getObj(self): 
115          return self._obj 
116   
117 -    def getTime(self): 
118          """Return the time at which this cache object was created""" 
119          return self._time 
120