#
# This module implements general purpose caching system
#
-from __future__ import with_statement
+
import time
import threading
import pickle
from datetime import datetime
-# maximum lifetime of cached data (in seconds)
-MAX_CACHE_TTL = 60 * 60
+# maximum lifetime of cached data (in seconds)
+DEFAULT_CACHE_TTL = 60 * 60
+
class CacheData:
expires = None
lock = None
- def __init__(self, data, ttl = MAX_CACHE_TTL):
+ def __init__(self, data, ttl=DEFAULT_CACHE_TTL):
self.lock = threading.RLock()
self.data = data
self.renew(ttl)
def get_expires_date(self):
return str(datetime.fromtimestamp(self.expires))
- def renew(self, ttl = MAX_CACHE_TTL):
+ def renew(self, ttl=DEFAULT_CACHE_TTL):
self.created = time.time()
- self.expires = self.created + ttl
-
- def set_data(self, data, renew=True, ttl = MAX_CACHE_TTL):
- with self.lock:
+ self.expires = self.created + ttl
+
+ def set_data(self, data, renew=True, ttl=DEFAULT_CACHE_TTL):
+ with self.lock:
self.data = data
if renew:
self.renew(ttl)
-
+
def get_data(self):
return self.data
-
def dump(self):
return self.__dict__
def __str__(self):
- return str(self.dump())
-
+ return str(self.dump())
+
def tostring(self):
return self.__str__()
def __setstate__(self, d):
self.__dict__.update(d)
self.lock = threading.RLock()
-
+
class Cache:
- cache = {}
+ cache = {}
lock = threading.RLock()
def __init__(self, filename=None):
if filename:
self.load_from_file(filename)
-
- def add(self, key, value, ttl = MAX_CACHE_TTL):
+
+ def add(self, key, value, ttl=DEFAULT_CACHE_TTL):
with self.lock:
- if self.cache.has_key(key):
+ if key in self.cache:
self.cache[key].set_data(value, ttl=ttl)
else:
self.cache[key] = CacheData(value, ttl)
-
+
def get(self, key):
data = self.cache.get(key)
- if not data:
+ if not data:
data = None
elif data.is_expired():
self.pop(key)
- data = None
+ data = None
else:
data = data.get_data()
return data
def pop(self, key):
if key in self.cache:
- self.cache.pop(key)
+ self.cache.pop(key)
def dump(self):
result = {}
return result
def __str__(self):
- return str(self.dump())
-
+ return str(self.dump())
+
def tostring(self):
- return self.__str()
+ return self.__str()
def save_to_file(self, filename):
- f = open(filename, 'w')
+ f = open(filename, 'wb')
pickle.dump(self.cache, f)
def load_from_file(self, filename):
- f = open(filename, 'r')
+ f = open(filename, 'rb')
self.cache = pickle.load(f)