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
|
import random
import socket
import time
from collections import OrderedDict
from django.conf import settings
from redis.exceptions import ConnectionError, ResponseError, TimeoutError
from ..exceptions import ConnectionInterrupted
from .default import DEFAULT_TIMEOUT, DefaultClient
_main_exceptions = (ConnectionError, ResponseError, TimeoutError, socket.timeout)
class Marker:
"""
Dummy class for use as
marker for herded keys.
"""
pass
def _is_expired(x, herd_timeout: int) -> bool:
if x >= herd_timeout:
return True
val = x + random.randint(1, herd_timeout)
if val >= herd_timeout:
return True
return False
class HerdClient(DefaultClient):
def __init__(self, *args, **kwargs):
self._marker = Marker()
self._herd_timeout = getattr(settings, "CACHE_HERD_TIMEOUT", 60)
super().__init__(*args, **kwargs)
def _pack(self, value, timeout):
herd_timeout = (timeout or self._backend.default_timeout) + int(time.time())
return self._marker, value, herd_timeout
def _unpack(self, value):
try:
marker, unpacked, herd_timeout = value
except (ValueError, TypeError):
return value, False
if not isinstance(marker, Marker):
return value, False
now = int(time.time())
if herd_timeout < now:
x = now - herd_timeout
return unpacked, _is_expired(x, self._herd_timeout)
return unpacked, False
def set(
self,
key,
value,
timeout=DEFAULT_TIMEOUT,
version=None,
client=None,
nx=False,
xx=False,
):
if timeout is DEFAULT_TIMEOUT:
timeout = self._backend.default_timeout
if timeout is None or timeout <= 0:
return super().set(
key,
value,
timeout=timeout,
version=version,
client=client,
nx=nx,
xx=xx,
)
packed = self._pack(value, timeout)
real_timeout = timeout + self._herd_timeout
return super().set(
key, packed, timeout=real_timeout, version=version, client=client, nx=nx
)
def get(self, key, default=None, version=None, client=None):
packed = super().get(key, default=default, version=version, client=client)
val, refresh = self._unpack(packed)
if refresh:
return default
return val
def get_many(self, keys, version=None, client=None):
if client is None:
client = self.get_client(write=False)
if not keys:
return {}
recovered_data = OrderedDict()
new_keys = [self.make_key(key, version=version) for key in keys]
map_keys = dict(zip(new_keys, keys))
try:
results = client.mget(*new_keys)
except _main_exceptions as e:
raise ConnectionInterrupted(connection=client) from e
for key, value in zip(new_keys, results):
if value is None:
continue
val, refresh = self._unpack(self.decode(value))
recovered_data[map_keys[key]] = None if refresh else val
return recovered_data
def set_many(
self, data, timeout=DEFAULT_TIMEOUT, version=None, client=None, herd=True
):
"""
Set a bunch of values in the cache at once from a dict of key/value
pairs. This is much more efficient than calling set() multiple times.
If timeout is given, that timeout will be used for the key; otherwise
the default cache timeout will be used.
"""
if client is None:
client = self.get_client(write=True)
set_function = self.set if herd else super().set
try:
pipeline = client.pipeline()
for key, value in data.items():
set_function(key, value, timeout, version=version, client=pipeline)
pipeline.execute()
except _main_exceptions as e:
raise ConnectionInterrupted(connection=client) from e
def incr(self, *args, **kwargs):
raise NotImplementedError()
def decr(self, *args, **kwargs):
raise NotImplementedError()
def touch(self, key, timeout=DEFAULT_TIMEOUT, version=None, client=None):
if client is None:
client = self.get_client(write=True)
value = self.get(key, version=version, client=client)
if value is None:
return False
self.set(key, value, timeout=timeout, version=version, client=client)
return True
|
