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

Source code for dramatiq.rate_limits.backends.redis

# 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.
#
# 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/>.

import redis

from ..backend import RateLimiterBackend


[docs]class RedisBackend(RateLimiterBackend): """A rate limiter backend for Redis_. Parameters: client(StrictRedis): An optional client. If this is passed, then all other parameters are ignored. url(str): An optional connection URL. If both a URL and connection paramters are provided, the URL is used. **parameters(dict): Connection parameters are passed directly to :class:`redis.StrictRedis`. .. _redis: https://redis.io """ def __init__(self, *, client=None, url=None, **parameters): if url is not None: parameters["connection_pool"] = redis.ConnectionPool.from_url(url) self.client = client or redis.StrictRedis(**parameters) def add(self, key, value, ttl): return bool(self.client.set(key, value, px=ttl, nx=True)) def incr(self, key, amount, maximum, ttl): with self.client.pipeline() as pipe: while True: try: pipe.watch(key) value = int(pipe.get(key) or b"0") value += amount if value > maximum: return False pipe.multi() pipe.set(key, value, px=ttl) pipe.execute() return True except redis.WatchError: continue def decr(self, key, amount, minimum, ttl): with self.client.pipeline() as pipe: while True: try: pipe.watch(key) value = int(pipe.get(key) or b"0") value -= amount if value < minimum: return False pipe.multi() pipe.set(key, value, px=ttl) pipe.execute() return True except redis.WatchError: continue def incr_and_sum(self, key, keys, amount, maximum, ttl): with self.client.pipeline() as pipe: while True: try: # TODO: Drop non-callable keys in Dramatiq v2. key_list = keys() if callable(keys) else keys pipe.watch(key, *key_list) value = int(pipe.get(key) or b"0") value += amount if value > maximum: return False # Fetch keys again to account for net/server latency. values = pipe.mget(keys() if callable(keys) else keys) total = amount + sum(int(n) for n in values if n) if total > maximum: return False pipe.multi() pipe.set(key, value, px=ttl) pipe.execute() return True except redis.WatchError: continue def wait(self, key, timeout): assert timeout is None or timeout >= 1000, "wait timeouts must be >= 1000" event = self.client.brpoplpush(key, key, (timeout or 0) // 1000) return event == b"x" def wait_notify(self, key, ttl): with self.client.pipeline() as pipe: pipe.rpush(key, b"x") pipe.pexpire(key, ttl) pipe.execute()