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
|
Getting started!
================
A comprehensive, fast, pure-Python memcached client library.
Basic Usage
------------
.. code-block:: python
from pymemcache.client.base import Client
client = Client(('localhost', 11211))
client.set('some_key', 'some_value')
result = client.get('some_key')
Using a memcached cluster
-------------------------
This will use a consistent hashing algorithm to choose which server to
set/get the values from. It will also automatically rebalance depending
on if a server goes down.
.. code-block:: python
from pymemcache.client.hash import HashClient
client = HashClient([
('127.0.0.1', 11211),
('127.0.0.1', 11212)
])
client.set('some_key', 'some value')
result = client.get('some_key')
Serialization
--------------
.. code-block:: python
import json
from pymemcache.client.base import Client
def json_serializer(key, value):
if type(value) == str:
return value, 1
return json.dumps(value), 2
def json_deserializer(key, value, flags):
if flags == 1:
return value
if flags == 2:
return json.loads(value)
raise Exception("Unknown serialization format")
client = Client(('localhost', 11211), serializer=json_serializer,
deserializer=json_deserializer)
client.set('key', {'a':'b', 'c':'d'})
result = client.get('key')
Key Constraints
---------------
This client implements the ASCII protocol of memcached. This means keys should not
contain any of the following illegal characters:
> Keys cannot have spaces, new lines, carriage returns, or null characters.
We suggest that if you have unicode characters, or long keys, you use an effective
hashing mechanism before calling this client. At Pinterest, we have found that murmur3 hash is a
great candidate for this.
Best Practices
---------------
- Always set the connect_timeout and timeout arguments in the constructor to
avoid blocking your process when memcached is slow.
- Use the "noreply" flag for a significant performance boost. The "noreply"
flag is enabled by default for "set", "add", "replace", "append", "prepend",
and "delete". It is disabled by default for "cas", "incr" and "decr". It
obviously doesn't apply to any get calls.
- Use get_many and gets_many whenever possible, as they result in less
round trip times for fetching multiple keys.
- Use the "ignore_exc" flag to treat memcache/network errors as cache misses
on calls to the get* methods. This prevents failures in memcache, or network
errors, from killing your web requests. Do not use this flag if you need to
know about errors from memcache, and make sure you have some other way to
detect memcache server failures.
|
