Ticket #3241: memcached.py

File memcached.py, 1.6 KB (added by recalcitrare@…, 18 years ago)

revision of memcached backend that can handle keys > 250 characters or containing spaces

Line 
1"Memcached cache backend"
2
3from django.core.cache.backends.base import BaseCache, InvalidCacheBackendError
4
5try:
6 import memcache
7except ImportError:
8 raise InvalidCacheBackendError, "Memcached cache backend requires the 'memcache' library"
9
10#
11# The memcache module refuses to use keys longer than 250 characters or containing
12# "control characters", which it defines as anything with a decimal ASCII code below
13# 33. This definition includes the non-printable ASCII characters and the space character,
14# so to allow caching of very long URLs or URLs containing spaces we'll hash them.
15#
16try:
17 import hashlib
18 key_hasher = hashlib.sha1
19except ImportError:
20 import sha
21 key_hasher = sha.new
22
23class CacheClass(BaseCache):
24 def __init__(self, server, params):
25 BaseCache.__init__(self, params)
26 self._cache = memcache.Client(server.split(';'))
27
28 def hash_key(self, key):
29 if ' ' not in key and len(key) < memcache.SERVER_MAX_KEY_LENGTH:
30 return key
31
32 key_hash = key_hasher()
33 key_hash.update(key)
34 return key_hash.hexdigest()
35
36 def get(self, key, default=None):
37 val = self._cache.get(self.hash_key(key))
38 if val is None:
39 return default
40 else:
41 return val
42
43 def set(self, key, value, timeout=0):
44 self._cache.set(self.hash_key(key), value, timeout or self.default_timeout)
45
46 def delete(self, key):
47 self._cache.delete(self.hash_key(key))
48
49 def get_many(self, keys):
50 keys = [self.hash_key(key) for key in keys]
51 return self._cache.get_multi(keys)
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