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

  1  # 
  2  # (C) Copyright 2003-2010 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 714 2010-04-05 10:20:10Z jajcus $" 
 21  __docformat__="restructuredtext en" 
 22   
 23  import time 
 24  import threading 
 25   
 26  __all__ = ['ExpiringDictionary'] 
 27   
 28  sentinel = object() 
 29   
30 -class ExpiringDictionary(dict):
31 """An extension to standard Python dictionary objects which implements item 32 expiration. 33 34 Each item in ExpiringDictionary has its expiration time assigned, after 35 which the item is removed from the mapping. 36 37 :Ivariables: 38 - `_timeouts`: a dictionary with timeout values and timeout callback for 39 stored objects. 40 - `_default_timeout`: the default timeout value (in seconds from now). 41 - `_lock`: access synchronization lock. 42 :Types: 43 - `_timeouts`: `dict` 44 - `_default_timeout`: `int` 45 - `_lock`: `threading.RLock`""" 46 47 __slots__=['_timeouts','_default_timeout','_lock'] 48
49 - def __init__(self,default_timeout=300):
50 """Initialize an `ExpiringDictionary` object. 51 52 :Parameters: 53 - `default_timeout`: default timeout value for stored objects. 54 :Types: 55 - `default_timeout`: `int`""" 56 dict.__init__(self) 57 self._timeouts={} 58 self._default_timeout=default_timeout 59 self._lock=threading.RLock()
60
61 - def __delitem__(self,key):
62 self._lock.acquire() 63 try: 64 del self._timeouts[key] 65 return dict.__delitem__(self,key) 66 finally: 67 self._lock.release()
68
69 - def __getitem__(self,key):
70 self._lock.acquire() 71 try: 72 self._expire_item(key) 73 return dict.__getitem__(self,key) 74 finally: 75 self._lock.release()
76
77 - def pop(self,key,default=sentinel):
78 self._lock.acquire() 79 try: 80 self._expire_item(key) 81 del self._timeouts[key] 82 if default is not sentinel: 83 return dict.pop(self,key,default) 84 else: 85 return dict.pop(self,key) 86 finally: 87 self._lock.release()
88
89 - def __setitem__(self,key,value):
90 return self.set_item(key,value)
91
92 - def set_item(self,key,value,timeout=None,timeout_callback=None):
93 """Set item of the dictionary. 94 95 :Parameters: 96 - `key`: the key. 97 - `value`: the object to store. 98 - `timeout`: timeout value for the object (in seconds from now). 99 - `timeout_callback`: function to be called when the item expires. 100 The callback should accept none, one (the key) or two (the key 101 and the value) arguments. 102 :Types: 103 - `key`: any hashable value 104 - `value`: any python object 105 - `timeout`: `int` 106 - `timeout_callback`: callable""" 107 self._lock.acquire() 108 try: 109 if not timeout: 110 timeout=self._default_timeout 111 self._timeouts[key]=(time.time()+timeout,timeout_callback) 112 return dict.__setitem__(self,key,value) 113 finally: 114 self._lock.release()
115
116 - def expire(self):
117 """Do the expiration of dictionary items. 118 119 Remove items that expired by now from the dictionary.""" 120 self._lock.acquire() 121 try: 122 for k in self._timeouts.keys(): 123 self._expire_item(k) 124 finally: 125 self._lock.release()
126
127 - def _expire_item(self,key):
128 """Do the expiration of a dictionary item. 129 130 Remove the item if it has expired by now. 131 132 :Parameters: 133 - `key`: key to the object. 134 :Types: 135 - `key`: any hashable value""" 136 (timeout,callback)=self._timeouts[key] 137 if timeout<=time.time(): 138 item = dict.pop(self, key) 139 del self._timeouts[key] 140 if callback: 141 try: 142 callback(key,item) 143 except TypeError: 144 try: 145 callback(key) 146 except TypeError: 147 callback()
148 149 # vi: sts=4 et sw=4 150