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
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
|
#!/usr/bin/env python
# Copyright (c) 2009, Giampaolo Rodola'. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Module which provides compatibility with older Python versions."""
import collections
import functools
import sys
__all__ = ["PY3", "long", "xrange", "unicode", "callable", "lru_cache"]
PY3 = sys.version_info[0] == 3
if PY3:
long = int
xrange = range
unicode = str
def u(s):
return s
else:
long = long
xrange = xrange
unicode = unicode
def u(s):
return unicode(s, "unicode_escape")
# removed in 3.0, reintroduced in 3.2
try:
callable = callable
except NameError:
def callable(obj):
return any("__call__" in klass.__dict__ for klass in type(obj).__mro__)
# --- stdlib additions
# py 3.2 functools.lru_cache
# Taken from: http://code.activestate.com/recipes/578078
# Credit: Raymond Hettinger
try:
from functools import lru_cache
except ImportError:
try:
from threading import RLock
except ImportError:
from dummy_threading import RLock
_CacheInfo = collections.namedtuple(
"CacheInfo", ["hits", "misses", "maxsize", "currsize"])
class _HashedSeq(list):
__slots__ = 'hashvalue'
def __init__(self, tup, hash=hash):
self[:] = tup
self.hashvalue = hash(tup)
def __hash__(self):
return self.hashvalue
def _make_key(args, kwds, typed,
kwd_mark=(object(), ),
fasttypes=set((int, str, frozenset, type(None))),
sorted=sorted, tuple=tuple, type=type, len=len):
key = args
if kwds:
sorted_items = sorted(kwds.items())
key += kwd_mark
for item in sorted_items:
key += item
if typed:
key += tuple(type(v) for v in args)
if kwds:
key += tuple(type(v) for k, v in sorted_items)
elif len(key) == 1 and type(key[0]) in fasttypes:
return key[0]
return _HashedSeq(key)
def lru_cache(maxsize=100, typed=False):
"""Least-recently-used cache decorator, see:
http://docs.python.org/3/library/functools.html#functools.lru_cache
"""
def decorating_function(user_function):
cache = dict()
stats = [0, 0]
HITS, MISSES = 0, 1
make_key = _make_key
cache_get = cache.get
_len = len
lock = RLock()
root = []
root[:] = [root, root, None, None]
nonlocal_root = [root]
PREV, NEXT, KEY, RESULT = 0, 1, 2, 3
if maxsize == 0:
def wrapper(*args, **kwds):
result = user_function(*args, **kwds)
stats[MISSES] += 1
return result
elif maxsize is None:
def wrapper(*args, **kwds):
key = make_key(args, kwds, typed)
result = cache_get(key, root)
if result is not root:
stats[HITS] += 1
return result
result = user_function(*args, **kwds)
cache[key] = result
stats[MISSES] += 1
return result
else:
def wrapper(*args, **kwds):
if kwds or typed:
key = make_key(args, kwds, typed)
else:
key = args
lock.acquire()
try:
link = cache_get(key)
if link is not None:
root, = nonlocal_root
link_prev, link_next, key, result = link
link_prev[NEXT] = link_next
link_next[PREV] = link_prev
last = root[PREV]
last[NEXT] = root[PREV] = link
link[PREV] = last
link[NEXT] = root
stats[HITS] += 1
return result
finally:
lock.release()
result = user_function(*args, **kwds)
lock.acquire()
try:
root, = nonlocal_root
if key in cache:
pass
elif _len(cache) >= maxsize:
oldroot = root
oldroot[KEY] = key
oldroot[RESULT] = result
root = nonlocal_root[0] = oldroot[NEXT]
oldkey = root[KEY]
root[KEY] = root[RESULT] = None
del cache[oldkey]
cache[key] = oldroot
else:
last = root[PREV]
link = [last, root, key, result]
last[NEXT] = root[PREV] = cache[key] = link
stats[MISSES] += 1
finally:
lock.release()
return result
def cache_info():
"""Report cache statistics"""
lock.acquire()
try:
return _CacheInfo(stats[HITS], stats[MISSES], maxsize,
len(cache))
finally:
lock.release()
def cache_clear():
"""Clear the cache and cache statistics"""
lock.acquire()
try:
cache.clear()
root = nonlocal_root[0]
root[:] = [root, root, None, None]
stats[:] = [0, 0]
finally:
lock.release()
wrapper.__wrapped__ = user_function
wrapper.cache_info = cache_info
wrapper.cache_clear = cache_clear
return functools.update_wrapper(wrapper, user_function)
return decorating_function
|
