Skip to content

Instantly share code, notes, and snippets.

@kkung
Created May 27, 2011 09:34
Show Gist options
  • Save kkung/994937 to your computer and use it in GitHub Desktop.
Save kkung/994937 to your computer and use it in GitHub Desktop.
Flask, session store in memcached
from flask import Flask, request, session, url_for, redirect, \
render_template, abort, g, flash
from werkzeug.contrib.sessions import Session, SessionStore
from cPickle import HIGHEST_PROTOCOL
from random import random
from flask import json
class MemcachedSessionStore(SessionStore):
def __init__(self, servers=None, key_prefix=None, default_timeout=300):
SessionStore.__init__(self)
if isinstance(servers, (list, tuple)):
try:
import cmemcache as memcache
is_cmemcache = True
except ImportError:
try:
import memcache
is_cmemcache = False
is_pylibmc = False
except ImprotError:
try:
import pylibmc as memcache
is_cmemcache = False
is_pylibmc = True
except ImportError:
raise RuntimeErorr(' no memcache module found ')
if is_cmemcache:
client = memcache.Client(map(str, servers))
try:
client.debuglog = lambda *a: None
except Exception:
pass
else:
if is_pylibmc:
client = memcache.Client(servers, False)
else:
client = memcache.Client(servers, False, HIGHEST_PROTOCOL)
else:
client = servers
self._memcache_client = client
self._memcache_key_prefix = key_prefix
self._memcache_timeout = default_timeout
def save(self, session):
key = self._get_memcache_key(session.sid)
data = json.dumps(dict(session))
print "{0}:{1}".format(key, data)
self._memcache_client.set( key, data )
def delete(self, session):
key = self._get_memcache_key(session.sid)
self._memcache_client.delete(key)
def get(self, sid):
key = self._get_memcache_key(sid)
data = self._memcache_client.get( key )
if data is not None:
data = json.loads(data)
else:
data = {}
return self.session_class( data, sid, False)
def _get_memcache_key(self, sid):
key = self._memcache_key_prefix + sid
if isinstance(key, unicode):
key = key.encode('utf-8')
return key
class SessionMixin(object):
__slots__ = ('session_key', 'session_store')
def open_session(self, request):
sid = request.cookies.get(self.session_key, None)
if sid is None:
return self.session_store.new()
else:
return self.session_store.get(sid)
def save_session(self, session, response):
if session.should_save:
self.session_store.save(session)
response.set_cookie(self.session_key, session.sid)
return response
class MyFlask( SessionMixin, Flask): pass
app = MyFlask(__name__)
app.session_key = '_sess_myflask'
app.session_store = MemcachedSessionStore(['127.0.0.1:1122'], 'myflask:')
@app.route('/a')
def a():
session['a'] = 'from a {0}'.format(random())
return u'''<!doctype html>
<html>
<head>
<title>Hello Test</title>
</head>
<body>
<h1>saved {0}</h1>
</body>
</html>'''.format( session['a'] )
@app.route('/b')
def b():
return u'''<!doctype html>
<html>
<head>
<title>Hello Test</title>
</head>
<body>
<h1>loaded {0}</h1>
</body>
</html>'''.format( session['a'] )
if __name__ == '__main__':
app.run(debug=True)
@kramer65
Copy link

Just a question; I also want to use memcached on my Ubuntu server, but how did you install the various memcached modules you import: import memcached and import cmemcache?

I tried pip install memcached and installed python-memcached, but to no avail:

>>> import memcached
Traceback (most recent call last):
  File "<input>", line 1, in <module>
ImportError: No module named memcached
>>> import cmemcached
Traceback (most recent call last):
  File "<input>", line 1, in <module>
ImportError: No module named cmemcached

Any idea how I can install those?

@r14c
Copy link

r14c commented Oct 13, 2015

You are importing cmemcached and memcached, but the module you want is cmemcache or memcache

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment