Source code for remoulade.rate_limits.backend

# 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


class RateLimiterBackend:
    """ABC for rate limiter backends."""

    def add(self, key: str, value: int, ttl: int) -> bool:  # pragma: no cover
        """Add a key to the backend iff it doesn't exist.

        Parameters:
          key(str): The key to add.
          value(int): The value to add.
          ttl(int): The max amount of time in milliseconds the key can
            live in the backend for.
        """
        raise NotImplementedError

    def incr(self, key: str, amount: int, maximum: int, ttl: int) -> bool:  # pragma: no cover
        """Atomically increment a key in the backend up to the given maximum.

        Parameters:
          key(str): The key to increment.
          amount(int): The amount to increment the value by.
          maximum(int): The maximum amount the value can have.
          ttl(int): The max amount of time in milliseconds the key can
            live in the backend for.

        Returns:
          bool: True if the key was successfully incremented.
        """
        raise NotImplementedError

    def decr(self, key: str, amount: int, minimum: int, ttl: int) -> bool:  # pragma: no cover
        """Atomically decrement a key in the backend up to the given maximum.

        Parameters:
          key(str): The key to decrement.
          amount(int): The amount to decrement the value by.
          minimum(int): The minimum amount the value can have.
          ttl(int): The max amount of time in milliseconds the key can
            live in the backend for.

        Returns:
          bool: True if the key was successfully decremented.
        """
        raise NotImplementedError

    def incr_and_sum(
        self, key: str, keys: Callable[[], List[str]], amount: int, maximum: int, ttl: int
    ):  # pragma: no cover
        """Atomically increment a key unless the sum of keys is greater than the given maximum.

        Parameters:
          key(str): The key to increment.
          keys(callable): A callable to return the list of keys to be
            summed over.
          amount(int): The amount to decrement the value by.
          maximum(int): The maximum sum of the keys.
          ttl(int): The max amount of time in milliseconds the key can
            live in the backend for.

        Returns:
          bool: True if the key was successfully incremented.
        """
        raise NotImplementedError