Source Code for Module ZenUtils.Map

  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  import threading 
 15  import time 
 16   
 17 -class Timed: 
 18      "Store elements in a map for the given time" 
 19   
 20 -    def __init__(self, map, timeout): 
 21          self.map = map 
 22          self.timeout = timeout 
 23          self.lastClean = 0 
 24   
 25   
 26 -    def clean(self, now = None): 
 27          "remove old values" 
 28          # FIXME O(N) search 
 29          if now is None: 
 30              now = time.time() 
 31          if self.lastClean + self.timeout > now: 
 32              return 
 33          for k, (v, t) in self.map.items(): 
 34              if t + self.timeout < now: 
 35                  del self.map[k] 
 36          self.lastClean = now 
 37   
 38       
 39 -    def get(self, key, default): 
 40          now = time.time() 
 41          self.clean(now) 
 42          v, t = self.map.get(key, (default, None) ) 
 43          if t is None or t + self.timeout < now: 
 44              return default 
 45          return v 
 46   
 47   
 48 -    def __getitem__(self, key): 
 49          now = time.time() 
 50          v, t = self.map[key] 
 51          if t + self.timeout < now: 
 52              del self.map[key] 
 53              raise KeyError 
 54          return v 
 55   
 56   
 57 -    def __setitem__(self, key, value): 
 58          now = time.time() 
 59          self.clean(now) 
 60          self.map[key] = (value, now) 
 61   
 62   
 63 -    def update(self, d): 
 64          now = time.time() 
 65          self.clean(now) 
 66          for k, v in d.items(): 
 67              self.map[k] = (v, now) 
 68   
 69   
 70 -class Locked: 
 71      "Use a simple lock for all read/write access to a map" 
 72   
 73 -    def __init__(self, map): 
 74          self.map = map 
 75          self.lock = threading.Lock() 
 76   
 77   
 78 -    def impl(self, m, *args, **kw): 
 79          "call a method on the map, with the lock held" 
 80          self.lock.acquire() 
 81          try: 
 82              return m(*args, **kw) 
 83          finally: 
 84              self.lock.release() 
 85   
 86           
 87 -    def has_key(self, *args, **kw): 
 88          return self.impl(self.map.has_key, *args, **kw) 
 89   
 90   
 91 -    def get(self, *args, **kw): 
 92          return self.impl(self.map.get, *args, **kw) 
 93   
 94           
 95 -    def __setitem__(self, *args, **kw): 
 96          return self.impl(self.map.__setitem__, *args, **kw) 
 97   
 98   
 99 -    def __getitem__(self, *args, **kw): 
100          return self.impl(self.map.__getitem__, *args, **kw) 
101   
102   
103 -    def update(self, *args, **kw): 
104          return self.impl(self.map.update, *args, **kw) 
105