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
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
|
"""
LFU cache Written by Shane Wang
https://medium.com/@epicshane/a-python-implementation-of-lfu-least-frequently-used-cache-with-o-1-time-complexity-e16b34a3c49b
https://github.com/luxigner/lfu_cache
Modified by Sep Dehpour
"""
from collections import defaultdict
from threading import Lock
from statistics import mean
from deepdiff.helper import not_found, dict_, SetOrdered
class CacheNode:
def __init__(self, key, report_type, value, freq_node, pre, nxt):
self.key = key
if report_type:
self.content = defaultdict(SetOrdered)
self.content[report_type].add(value)
else:
self.content = value
self.freq_node = freq_node
self.pre = pre # previous CacheNode
self.nxt = nxt # next CacheNode
def free_myself(self):
if self.freq_node.cache_head == self.freq_node.cache_tail: # type: ignore
self.freq_node.cache_head = self.freq_node.cache_tail = None # type: ignore
elif self.freq_node.cache_head == self: # type: ignore
self.nxt.pre = None # type: ignore
self.freq_node.cache_head = self.nxt # type: ignore
elif self.freq_node.cache_tail == self: # type: ignore
self.pre.nxt = None # type: ignore
self.freq_node.cache_tail = self.pre # type: ignore
else:
self.pre.nxt = self.nxt # type: ignore
self.nxt.pre = self.pre # type: ignore
self.pre = None
self.nxt = None
self.freq_node = None
class FreqNode:
def __init__(self, freq, pre, nxt):
self.freq = freq
self.pre = pre # previous FreqNode
self.nxt = nxt # next FreqNode
self.cache_head = None # CacheNode head under this FreqNode
self.cache_tail = None # CacheNode tail under this FreqNode
def count_caches(self):
if self.cache_head is None and self.cache_tail is None:
return 0
elif self.cache_head == self.cache_tail:
return 1
else:
return '2+'
def remove(self):
if self.pre is not None:
self.pre.nxt = self.nxt
if self.nxt is not None:
self.nxt.pre = self.pre
pre = self.pre
nxt = self.nxt
self.pre = self.nxt = self.cache_head = self.cache_tail = None
return (pre, nxt)
def pop_head_cache(self):
if self.cache_head is None and self.cache_tail is None:
return None
elif self.cache_head == self.cache_tail:
cache_head = self.cache_head
self.cache_head = self.cache_tail = None
return cache_head
else:
cache_head = self.cache_head
self.cache_head.nxt.pre = None # type: ignore
self.cache_head = self.cache_head.nxt # type: ignore
return cache_head
def append_cache_to_tail(self, cache_node):
cache_node.freq_node = self
if self.cache_head is None and self.cache_tail is None:
self.cache_head = self.cache_tail = cache_node
else:
cache_node.pre = self.cache_tail
cache_node.nxt = None
self.cache_tail.nxt = cache_node # type: ignore
self.cache_tail = cache_node
def insert_after_me(self, freq_node):
freq_node.pre = self
freq_node.nxt = self.nxt
if self.nxt is not None:
self.nxt.pre = freq_node
self.nxt = freq_node
def insert_before_me(self, freq_node):
if self.pre is not None:
self.pre.nxt = freq_node
freq_node.pre = self.pre
freq_node.nxt = self
self.pre = freq_node
class LFUCache:
def __init__(self, capacity):
self.cache = dict_() # {key: cache_node}
if capacity <= 0:
raise ValueError('Capacity of LFUCache needs to be positive.') # pragma: no cover.
self.capacity = capacity
self.freq_link_head = None
self.lock = Lock()
def get(self, key):
with self.lock:
if key in self.cache:
cache_node = self.cache[key]
freq_node = cache_node.freq_node
content = cache_node.content
self.move_forward(cache_node, freq_node)
return content
else:
return not_found
def set(self, key, report_type=None, value=None):
with self.lock:
if key in self.cache:
cache_node = self.cache[key]
if report_type:
cache_node.content[report_type].add(value)
else:
cache_node.content = value
else:
if len(self.cache) >= self.capacity:
self.dump_cache()
self.create_cache_node(key, report_type, value)
def __contains__(self, key):
return key in self.cache
def move_forward(self, cache_node, freq_node):
if freq_node.nxt is None or freq_node.nxt.freq != freq_node.freq + 1:
target_freq_node = FreqNode(freq_node.freq + 1, None, None)
target_empty = True
else:
target_freq_node = freq_node.nxt
target_empty = False
cache_node.free_myself()
target_freq_node.append_cache_to_tail(cache_node)
if target_empty:
freq_node.insert_after_me(target_freq_node)
if freq_node.count_caches() == 0:
if self.freq_link_head == freq_node:
self.freq_link_head = target_freq_node
freq_node.remove()
def dump_cache(self):
head_freq_node = self.freq_link_head
self.cache.pop(head_freq_node.cache_head.key) # type: ignore
head_freq_node.pop_head_cache() # type: ignore
if head_freq_node.count_caches() == 0: # type: ignore
self.freq_link_head = head_freq_node.nxt # type: ignore
head_freq_node.remove() # type: ignore
def create_cache_node(self, key, report_type, value):
cache_node = CacheNode(
key=key, report_type=report_type,
value=value, freq_node=None, pre=None, nxt=None)
self.cache[key] = cache_node
if self.freq_link_head is None or self.freq_link_head.freq != 0:
new_freq_node = FreqNode(0, None, None)
new_freq_node.append_cache_to_tail(cache_node)
if self.freq_link_head is not None:
self.freq_link_head.insert_before_me(new_freq_node)
self.freq_link_head = new_freq_node
else:
self.freq_link_head.append_cache_to_tail(cache_node)
def get_sorted_cache_keys(self):
result = [(i, freq.freq_node.freq) for i, freq in self.cache.items()]
result.sort(key=lambda x: -x[1])
return result
def get_average_frequency(self):
return mean(freq.freq_node.freq for freq in self.cache.values())
class DummyLFU:
def __init__(self, *args, **kwargs):
pass
set = __init__
get = __init__
def __contains__(self, key):
return False
|
