1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
|
"Thread-safe in-memory cache backend."
import time
try:
import cPickle as pickle
except ImportError:
import pickle
from django.core.cache.backends.base import BaseCache
from django.utils.synch import RWLock
class CacheClass(BaseCache):
def __init__(self, _, params):
BaseCache.__init__(self, params)
self._cache = {}
self._expire_info = {}
max_entries = params.get('max_entries', 300)
try:
self._max_entries = int(max_entries)
except (ValueError, TypeError):
self._max_entries = 300
cull_frequency = params.get('cull_frequency', 3)
try:
self._cull_frequency = int(cull_frequency)
except (ValueError, TypeError):
self._cull_frequency = 3
self._lock = RWLock()
def add(self, key, value, timeout=None):
self._lock.writer_enters()
try:
exp = self._expire_info.get(key)
if exp is None or exp <= time.time():
try:
self._set(key, pickle.dumps(value), timeout)
return True
except pickle.PickleError:
pass
return False
finally:
self._lock.writer_leaves()
def get(self, key, default=None):
self._lock.reader_enters()
try:
exp = self._expire_info.get(key)
if exp is None:
return default
elif exp > time.time():
try:
return pickle.loads(self._cache[key])
except pickle.PickleError:
return default
finally:
self._lock.reader_leaves()
self._lock.writer_enters()
try:
try:
del self._cache[key]
del self._expire_info[key]
except KeyError:
pass
return default
finally:
self._lock.writer_leaves()
def _set(self, key, value, timeout=None):
if len(self._cache) >= self._max_entries:
self._cull()
if timeout is None:
timeout = self.default_timeout
self._cache[key] = value
self._expire_info[key] = time.time() + timeout
def set(self, key, value, timeout=None):
self._lock.writer_enters()
# Python 2.4 doesn't allow combined try-except-finally blocks.
try:
try:
self._set(key, pickle.dumps(value), timeout)
except pickle.PickleError:
pass
finally:
self._lock.writer_leaves()
def has_key(self, key):
self._lock.reader_enters()
try:
exp = self._expire_info.get(key)
if exp is None:
return False
elif exp > time.time():
return True
finally:
self._lock.reader_leaves()
self._lock.writer_enters()
try:
try:
del self._cache[key]
del self._expire_info[key]
except KeyError:
pass
return False
finally:
self._lock.writer_leaves()
def _cull(self):
if self._cull_frequency == 0:
self.clear()
else:
doomed = [k for (i, k) in enumerate(self._cache) if i % self._cull_frequency == 0]
for k in doomed:
self._delete(k)
def _delete(self, key):
try:
del self._cache[key]
except KeyError:
pass
try:
del self._expire_info[key]
except KeyError:
pass
def delete(self, key):
self._lock.writer_enters()
try:
self._delete(key)
finally:
self._lock.writer_leaves()
def clear(self):
self._cache.clear()
self._expire_info.clear()
|
