Source code for remoulade.rate_limits.backends.redis
# This file is a part of Remoulade.
#
# Copyright (C) 2017,2018 CLEARTYPE SRL <bogdan@cleartype.io>
#
# Remoulade 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.
#
# Remoulade 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/>.
from typing import Callable, List
import redis
from ..backend import RateLimiterBackend
[docs]class RedisBackend(RateLimiterBackend):
"""A rate limiter backend for Redis_.
Parameters:
client(Redis): 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.Redis`.
.. _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.Redis(**parameters)
def add(self, key: str, value: int, ttl: int) -> bool:
return bool(self.client.set(key, value, px=ttl, nx=True))
def incr(self, key: str, amount: int, maximum: int, ttl: int) -> bool:
with self.client.pipeline() as pipe:
while True:
try:
pipe.watch(key)
value = int(pipe.get(key) or b"0") # type: ignore
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: str, amount: int, minimum: int, ttl: int) -> bool:
with self.client.pipeline() as pipe:
while True:
try:
pipe.watch(key)
value = int(pipe.get(key) or b"0") # type: ignore
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: str, keys: Callable[[], List[str]], amount: int, maximum: int, ttl: int) -> bool:
with self.client.pipeline() as pipe:
while True:
try:
# TODO: Drop non-callable keys in Remoulade v2.
key_list = keys() if callable(keys) else keys
pipe.watch(key, *key_list)
value = int(pipe.get(key) or b"0") # type: ignore
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) # type: ignore
if total > maximum:
return False
pipe.multi()
pipe.set(key, value, px=ttl)
pipe.execute()
return True
except redis.WatchError:
continue