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
|
import functools
from .keys import hashkey
def cached(cache, key=hashkey, lock=None):
"""Decorator to wrap a function with a memoizing callable that saves
results in a cache.
"""
def decorator(func):
if cache is None:
def wrapper(*args, **kwargs):
return func(*args, **kwargs)
elif lock is None:
def wrapper(*args, **kwargs):
k = key(*args, **kwargs)
try:
return cache[k]
except KeyError:
pass # key not found
v = func(*args, **kwargs)
try:
cache[k] = v
except ValueError:
pass # value too large
return v
else:
def wrapper(*args, **kwargs):
k = key(*args, **kwargs)
try:
with lock:
return cache[k]
except KeyError:
pass # key not found
v = func(*args, **kwargs)
# in case of a race, prefer the item already in the cache
try:
with lock:
return cache.setdefault(k, v)
except ValueError:
return v # value too large
return functools.update_wrapper(wrapper, func)
return decorator
def cachedmethod(cache, key=hashkey, lock=None):
"""Decorator to wrap a class or instance method with a memoizing
callable that saves results in a cache.
"""
def decorator(method):
if lock is None:
def wrapper(self, *args, **kwargs):
c = cache(self)
if c is None:
return method(self, *args, **kwargs)
k = key(*args, **kwargs)
try:
return c[k]
except KeyError:
pass # key not found
v = method(self, *args, **kwargs)
try:
c[k] = v
except ValueError:
pass # value too large
return v
else:
def wrapper(self, *args, **kwargs):
c = cache(self)
if c is None:
return method(self, *args, **kwargs)
k = key(*args, **kwargs)
try:
with lock(self):
return c[k]
except KeyError:
pass # key not found
v = method(self, *args, **kwargs)
# in case of a race, prefer the item already in the cache
try:
with lock(self):
return c.setdefault(k, v)
except ValueError:
return v # value too large
return functools.update_wrapper(wrapper, method)
return decorator
|
