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
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
|
from collections import defaultdict
from uhashring import HashRing
from bmemcached.client import SOCKET_TIMEOUT
from bmemcached.client.mixin import ClientMixin
from bmemcached.compat import pickle
class DistributedClient(ClientMixin):
"""This is intended to be a client class which implement standard cache interface that common libs do...
It tries to distribute keys over the specified servers using `HashRing` consistent hash.
"""
def __init__(self, servers=('127.0.0.1:11211',), username=None, password=None, compression=None,
socket_timeout=SOCKET_TIMEOUT, pickle_protocol=0, pickler=pickle.Pickler, unpickler=pickle.Unpickler,
tls_context=None):
super(DistributedClient, self).__init__(servers, username, password, compression, socket_timeout,
pickle_protocol, pickler, unpickler, tls_context)
self._ring = HashRing(self._servers)
def _get_server(self, key):
return self._ring.get_node(key)
def delete(self, key, cas=0):
"""
Delete a key/value from server. If key does not exist, it returns True.
:param key: Key's name to be deleted
:param cas: CAS of the key
:return: True in case o success and False in case of failure.
"""
server = self._get_server(key)
return server.delete(key, cas)
def delete_multi(self, keys):
servers = defaultdict(list)
for key in keys:
server_key = self._get_server(key)
servers[server_key].append(key)
return all([server.delete_multi(keys_) for server, keys_ in servers.items()])
def set(self, key, value, time=0, compress_level=-1):
"""
Set a value for a key on server.
:param key: Key's name
:type key: str
:param value: A value to be stored on server.
:type value: object
:param time: Time in seconds that your key will expire.
:type time: int
:param compress_level: How much to compress.
0 = no compression, 1 = fastest, 9 = slowest but best,
-1 = default compression level.
:type compress_level: int
:return: True in case of success and False in case of failure
:rtype: bool
"""
server = self._get_server(key)
return server.set(key, value, time, compress_level)
def set_multi(self, mappings, time=0, compress_level=-1):
"""
Set multiple keys with it's values on server.
:param mappings: A dict with keys/values
:type mappings: dict
:param time: Time in seconds that your key will expire.
:type time: int
:param compress_level: How much to compress.
0 = no compression, 1 = fastest, 9 = slowest but best,
-1 = default compression level.
:type compress_level: int
:return: List of keys that failed to be set on any server.
:rtype: list
"""
if not mappings:
return []
returns = set()
server_mappings = defaultdict(dict)
for key, value in mappings.items():
server_key = self._get_server(key)
server_mappings[server_key].update([(key, value)])
for server, m in server_mappings.items():
returns |= set(server.set_multi(m, time, compress_level))
return list(returns)
def add(self, key, value, time=0, compress_level=-1):
"""
Add a key/value to server ony if it does not exist.
:param key: Key's name
:type key: six.string_types
:param value: A value to be stored on server.
:type value: object
:param time: Time in seconds that your key will expire.
:type time: int
:param compress_level: How much to compress.
0 = no compression, 1 = fastest, 9 = slowest but best,
-1 = default compression level.
:type compress_level: int
:return: True if key is added False if key already exists
:rtype: bool
"""
server = self._get_server(key)
return server.add(key, value, time, compress_level)
def replace(self, key, value, time=0, compress_level=-1):
"""
Replace a key/value to server ony if it does exist.
:param key: Key's name
:type key: six.string_types
:param value: A value to be stored on server.
:type value: object
:param time: Time in seconds that your key will expire.
:type time: int
:param compress_level: How much to compress.
0 = no compression, 1 = fastest, 9 = slowest but best,
-1 = default compression level.
:type compress_level: int
:return: True if key is replace False if key does not exists
:rtype: bool
"""
server = self._get_server(key)
return server.replace(key, value, time, compress_level)
def get(self, key, default=None, get_cas=False):
"""
Get a key from server.
:param key: Key's name
:type key: six.string_types
:param default: In case memcached does not find a key, return a default value
:param get_cas: If true, return (value, cas), where cas is the new CAS value.
:type get_cas: boolean
:return: Returns a key data from server.
:rtype: object
"""
server = self._get_server(key)
value, cas = server.get(key)
if value is not None:
if get_cas:
return value, cas
return value
if default is not None:
if get_cas:
return default, None
return default
if get_cas:
return None, None
def get_multi(self, keys, get_cas=False):
"""
Get multiple keys from server.
:param keys: A list of keys to from server.
:type keys: list
:param get_cas: If get_cas is true, each value is (data, cas), with each result's CAS value.
:type get_cas: boolean
:return: A dict with all requested keys.
:rtype: dict
"""
servers = defaultdict(list)
d = {}
for key in keys:
server_key = self._get_server(key)
servers[server_key].append(key)
for server, keys in servers.items():
results = server.get_multi(keys)
if not get_cas:
# Remove CAS data
for key, (value, cas) in results.items():
results[key] = value
d.update(results)
return d
def gets(self, key):
server = self._get_server(key)
return server.get(key)
def cas(self, key, value, cas, time=0, compress_level=-1):
"""
Set a value for a key on server if its CAS value matches cas.
:param key: Key's name
:type key: six.string_types
:param value: A value to be stored on server.
:type value: object
:param cas: The CAS value previously obtained from a call to get*.
:type cas: int
:param time: Time in seconds that your key will expire.
:type time: int
:param compress_level: How much to compress.
0 = no compression, 1 = fastest, 9 = slowest but best,
-1 = default compression level.
:type compress_level: int
:return: True in case of success and False in case of failure
:rtype: bool
"""
server = self._get_server(key)
return server.cas(key, value, cas, time, compress_level)
def incr(self, key, value):
"""
Increment a key, if it exists, returns it's actual value, if it don't, return 0.
:param key: Key's name
:type key: six.string_types
:param value: Number to be incremented
:type value: int
:return: Actual value of the key on server
:rtype: int
"""
server = self._get_server(key)
return server.incr(key, value)
def decr(self, key, value):
"""
Decrement a key, if it exists, returns it's actual value, if it don't, return 0.
Minimum value of decrement return is 0.
:param key: Key's name
:type key: six.string_types
:param value: Number to be decremented
:type value: int
:return: Actual value of the key on server
:rtype: int
"""
server = self._get_server(key)
return server.decr(key, value)
|
