Package pyxmpp :: Module expdict
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Source Code for Module pyxmpp.expdict

  1  # 
  2  # (C) Copyright 2003-2004 Jacek Konieczny <jajcus@jajcus.net> 
  3  # 
  4  # This program is free software; you can redistribute it and/or modify 
  5  # it under the terms of the GNU Lesser General Public License Version 
  6  # 2.1 as published by the Free Software Foundation. 
  7  # 
  8  # This program is distributed in the hope that it will be useful, 
  9  # but WITHOUT ANY WARRANTY; without even the implied warranty of 
 10  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 11  # GNU Lesser General Public License for more details. 
 12  # 
 13  # You should have received a copy of the GNU Lesser General Public 
 14  # License along with this program; if not, write to the Free Software 
 15  # Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 
 16  # 
 17   
 18  """Dictionary with item expiration.""" 
 19   
 20  __revision__="$Id: expdict.py 600 2005-08-19 10:45:03Z jajcus $" 
 21  __docformat__="restructuredtext en" 
 22   
 23  import time 
 24  import threading 
 25   
26 -class ExpiringDictionary(dict):
27 """An extension to standard Python dictionary objects which implements item 28 expiration. 29 30 Each item in ExpiringDictionary has its expiration time assigned, after 31 which the item is removed from the mapping. 32 33 :Ivariables: 34 - `_timeouts`: a dictionary with timeout values and timeout callback for 35 stored objects. 36 - `_default_timeout`: the default timeout value (in seconds from now). 37 - `_lock`: access synchronization lock. 38 :Types: 39 - `_timeouts`: `dict` 40 - `_default_timeout`: `int` 41 - `_lock`: `threading.RLock`""" 42 43 __slots__=['_timeouts','_default_timeout','_lock'] 44
45 - def __init__(self,default_timeout=300):
46 """Initialize an `ExpiringDictionary` object. 47 48 :Parameters: 49 - `default_timeout`: default timeout value for stored objects. 50 :Types: 51 - `default_timeout`: `int`""" 52 dict.__init__(self) 53 self._timeouts={} 54 self._default_timeout=default_timeout 55 self._lock=threading.RLock()
56
57 - def __delitem__(self,key):
58 self._lock.acquire() 59 try: 60 del self._timeouts[key] 61 return dict.__delitem__(self,key) 62 finally: 63 self._lock.release()
64
65 - def __getitem__(self,key):
66 self._lock.acquire() 67 try: 68 self._expire_item(key) 69 return dict.__getitem__(self,key) 70 finally: 71 self._lock.release()
72
73 - def __setitem__(self,key,value):
74 return self.set_item(key,value)
75
76 - def set_item(self,key,value,timeout=None,timeout_callback=None):
77 """Set item of the dictionary. 78 79 :Parameters: 80 - `key`: the key. 81 - `value`: the object to store. 82 - `timeout`: timeout value for the object (in seconds from now). 83 - `timeout_callback`: function to be called when the item expires. 84 The callback should accept none, one (the key) or two (the key 85 and the value) arguments. 86 :Types: 87 - `key`: any hashable value 88 - `value`: any python object 89 - `timeout`: `int` 90 - `timeout_callback`: callable""" 91 self._lock.acquire() 92 try: 93 if not timeout: 94 timeout=self._default_timeout 95 self._timeouts[key]=(time.time()+timeout,timeout_callback) 96 return dict.__setitem__(self,key,value) 97 finally: 98 self._lock.release()
99
100 - def expire(self):
101 """Do the expiration of dictionary items. 102 103 Remove items that expired by now from the dictionary.""" 104 self._lock.acquire() 105 try: 106 for k in self._timeouts.keys(): 107 self._expire_item(k) 108 finally: 109 self._lock.release()
110
111 - def _expire_item(self,key):
112 """Do the expiration of a dictionary item. 113 114 Remove the item if it has expired by now. 115 116 :Parameters: 117 - `key`: key to the object. 118 :Types: 119 - `key`: any hashable value""" 120 (timeout,callback)=self._timeouts[key] 121 if timeout<=time.time(): 122 if callback: 123 try: 124 callback(key,dict.__getitem__(self,key)) 125 except TypeError: 126 try: 127 callback(key) 128 except TypeError: 129 callback() 130 del self[key]
131 132 # vi: sts=4 et sw=4 133