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kkung/app.py

Created May 27, 2011 09:34
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Flask, session store in memcached
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app.py
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
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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
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r14c commented Oct 13, 2015

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

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