Ticket #6847: filebased.py

File filebased.py, 2.5 KB (added by xinbin <xinbin@…>, 17 years ago)
Line 
1"File-based cache backend"
2
3from django.core.cache.backends.simple import CacheClass as SimpleCacheClass
4import os, time, urllib
5try:
6 import cPickle as pickle
7except ImportError:
8 import pickle
9
10class CacheClass(SimpleCacheClass):
11 def __init__(self, dir, params):
12 self._dir = dir
13 if not os.path.exists(self._dir):
14 self._createdir()
15 SimpleCacheClass.__init__(self, dir, params)
16 del self._cache
17 del self._expire_info
18
19 def get(self, key, default=None):
20 fname = self._key_to_file(key)
21 try:
22 f = open(fname, 'rb')
23 exp = pickle.load(f)
24 now = time.time()
25 if exp < now:
26 f.close()
27 os.remove(fname)
28 else:
29 return pickle.load(f)
30 except (IOError, OSError, EOFError, pickle.PickleError):
31 pass
32 return default
33
34 def set(self, key, value, timeout=None):
35 fname = self._key_to_file(key)
36 if timeout is None:
37 timeout = self.default_timeout
38
39 namespacedir = os.path.dirname(fname)
40 try:
41 filelist = os.listdir(namespacedir)
42 except (IOError, OSError):
43 self._createdir(namespacedir)
44 filelist = []
45 if len(filelist) > self._max_entries:
46 self._cull(filelist)
47
48 try:
49 f = open(fname, 'wb')
50 now = time.time()
51 pickle.dump(now + timeout, f, 2)
52 pickle.dump(value, f, 2)
53 except (IOError, OSError):
54 pass
55
56 def delete(self, key):
57 try:
58 os.remove(self._key_to_file(key))
59 except (IOError, OSError):
60 pass
61
62 def has_key(self, key):
63 return os.path.exists(self._key_to_file(key))
64
65 def _cull(self, filelist):
66 if self._cull_frequency == 0:
67 doomed = filelist
68 else:
69 doomed = [k for (i, k) in enumerate(filelist) if i % self._cull_frequency == 0]
70 for fname in doomed:
71 try:
72 os.remove(os.path.join(self._dir, fname))
73 except (IOError, OSError):
74 pass
75
76 def _createdir(self, dir = None):
77 if dir == None:
78 dir = self._dir
79 try:
80 os.makedirs(dir)
81 except OSError:
82 raise EnvironmentError, "Cache directory '%s' does not exist and could not be created'" % self._dir
83
84 def _key_to_file(self, key):
85 return os.path.join(self._dir, (key))
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