Hi,
I don't recall if I've already submitted this enhancement...
I've written a memcached based Session that others might find useful. Feel
free to use as you wish.
Usage:
1. Name the file SessionMemcachedStore.py in WebKit directory
2. Configure your Application.config:
SessionStore = 'WebKit.SessionMemcachedStore'
SessionMemcachedServers = ['127.0.0.1:11211']
SessionTimeout = 180 # minutes
Best Regards,
Steve
import threading
from memcache import memcache
from WebKit.SessionStore import SessionStore
debug = False
class SessionMemcachedStore(SessionStore, threading.local):
A session memached store.
Stores the sessions in a single memcached using 'last write wins'
semantics.
This is useful for various situations:
1. Fault tolerance
2. Clustering
In clustering configurations with concurrent writes for the same
session(s) the last writer will always overwrite the session.
Cleaning/timing out of sessions is performed by the memcached(s)
themselves
since no one appserver can know about the existence of all sessions or
the last access for a given session. Besides it is built in memcached
functionality. Consequently, correct sizing of memcached(s) is necessary
to hold all user's session data.
## Init ##
def __init__(self, app):
threading.local.__init__(self)
SessionStore.__init__(self, app)
self._memcachedServers = app.setting(
'MemcachedServers', ['127.0.0.1:11211'])
# timeout in seconds
self._sessionTimeout = app.setting(
'SessionTimeout', 180) * 60
## try:
## import cPickle as pickle
## except ImportError:
## import pickle
import pickle
self._client = memcache.Client(self._memcachedServers,
pickleProtocol=pickle.HIGHEST_PROTOCOL)
## Access ##
def __len__(self):
if debug:
print ' len', len(self.keys())
return len(self.keys())
def __getitem__(self, key):
if debug:
print ' getitem(%s)' % (key)
# returns None if key non-existent or no server to contact
value = self._client.get(key)
if value is None:
# SessionStore expects KeyError when no result
raise KeyError
return value
def __setitem__(self, key, item):
if debug:
print ' setitem(%s, %s)' % (key, item)
try:
val = self._client.set(key, item, time=self._sessionTimeout)
if not val:
raise Exception
except Exception, e:
# Not able to store the session is a failure
print Error saving session '%s' to memcached: %s % (key, e)
self.application().handleException()
def __delitem__(self, key):
In contracts with SessionFileStore not finding a key to delete
isn't a KeyError
if debug:
print ' delitem(%s)' % (key)
self._client.delete(key)
def removeKey(self, key):
pass
def has_key(self, key):
if debug:
print has_key(%s) % (key)
return self._client.get(key) is not None
def keys(self):
if debug:
print keys()
return []
def clear(self):
memcache handles clearing keys itself
if debug:
print clear()
def setdefault(self, key, default):
return value associated with key otherwise set key to default and
return default
if debug:
print ' setdefault (%s, %s)' % (key, default)
try:
return self[key]
except KeyError:
self[key] = default
return default
## Application support ##
def storeSession(self, session):
if debug:
print storeSession(%s) % (session)
key = session.identifier()
self[key] = session
def storeAllSessions(self):
pass
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