Warning: This document is for the development version of Dramatiq.

Source code for dramatiq.results.backends.memcached

# This file is a part of Dramatiq.
#
# Copyright (C) 2017,2018 CLEARTYPE SRL <bogdan@cleartype.io>
#
# Dramatiq is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or (at
# your option) any later version.
#
# Dramatiq is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
# License for more details.
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# You should have received a copy of the GNU Lesser General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

from pylibmc import Client, ClientPool

from ..backend import Missing, ResultBackend


[docs]class MemcachedBackend(ResultBackend): """A result backend for Memcached_. This backend uses long polling to retrieve results. Parameters: namespace(str): A string with which to prefix result keys. encoder(Encoder): The encoder to use when storing and retrieving result data. Defaults to :class:`.JSONEncoder`. pool(ClientPool): An optional pylibmc client pool to use. If this is passed, all other connection params are ignored. pool_size(int): The size of the connection pool to use. **parameters(dict): Connection parameters are passed directly to :class:`pylibmc.Client`. .. _memcached: https://memcached.org """ def __init__(self, *, namespace="dramatiq-results", encoder=None, pool=None, pool_size=8, **parameters): super().__init__(namespace=namespace, encoder=encoder) self.pool = pool or ClientPool(Client(**parameters), pool_size) def _get(self, message_key): with self.pool.reserve(block=True) as client: data = client.get(message_key) if data is not None: return self.encoder.decode(data) return Missing def _store(self, message_key, result, ttl): result_data = self.encoder.encode(result) with self.pool.reserve(block=True) as client: client.set(message_key, result_data, time=int(ttl / 1000))