你正在阅读 Celery 3.1 的文档。开发版本文档见: 此处.
# -*- coding: utf-8 -*-
"""
celery.backends.cache
~~~~~~~~~~~~~~~~~~~~~
Memcache and in-memory cache result backend.
"""
from __future__ import absolute_import
from kombu.utils import cached_property
from celery.datastructures import LRUCache
from celery.exceptions import ImproperlyConfigured
from .base import KeyValueStoreBackend
_imp = [None]
REQUIRES_BACKEND = """\
The memcached backend requires either pylibmc or python-memcached.\
"""
UNKNOWN_BACKEND = """\
The cache backend %r is unknown,
Please use one of the following backends instead: %s\
"""
[文档]def import_best_memcache():
if _imp[0] is None:
is_pylibmc = False
try:
import pylibmc as memcache
is_pylibmc = True
except ImportError:
try:
import memcache # noqa
except ImportError:
raise ImproperlyConfigured(REQUIRES_BACKEND)
_imp[0] = (is_pylibmc, memcache)
return _imp[0]
[文档]def get_best_memcache(*args, **kwargs):
behaviors = kwargs.pop('behaviors', None)
is_pylibmc, memcache = import_best_memcache()
client = memcache.Client(*args, **kwargs)
if is_pylibmc and behaviors is not None:
client.behaviors = behaviors
return client
[文档]class DummyClient(object):
def __init__(self, *args, **kwargs):
self.cache = LRUCache(limit=5000)
[文档] def get_multi(self, keys):
cache = self.cache
return dict((k, cache[k]) for k in keys if k in cache)
backends = {'memcache': lambda: get_best_memcache,
'memcached': lambda: get_best_memcache,
'pylibmc': lambda: get_best_memcache,
'memory': lambda: DummyClient}
[文档]class CacheBackend(KeyValueStoreBackend):
servers = None
supports_native_join = True
implements_incr = True
def __init__(self, expires=None, backend=None, options={}, **kwargs):
super(CacheBackend, self).__init__(self, **kwargs)
self.options = dict(self.app.conf.CELERY_CACHE_BACKEND_OPTIONS,
**options)
self.backend = backend or self.app.conf.CELERY_CACHE_BACKEND
if self.backend:
self.backend, _, servers = self.backend.partition('://')
self.servers = servers.rstrip('/').split(';')
self.expires = self.prepare_expires(expires, type=int)
try:
self.Client = backends[self.backend]()
except KeyError:
raise ImproperlyConfigured(UNKNOWN_BACKEND % (
self.backend, ', '.join(backends)))
[文档] def on_chord_apply(self, group_id, body, result=None, **kwargs):
self.client.set(self.get_key_for_chord(group_id), '0', time=86400)
@cached_property
def __reduce__(self, args=(), kwargs={}):
servers = ';'.join(self.servers)
backend = '%s://%s/' % (self.backend, servers)
kwargs.update(
dict(backend=backend,
expires=self.expires,
options=self.options))
return super(CacheBackend, self).__reduce__(args, kwargs)