from __future__ import annotations
import time
from typing import TYPE_CHECKING
from packaging.version import Version
from limits.typing import Optional, RedisClient, ScriptP, Tuple, Type, Union
from ..util import get_package_data
from .base import MovingWindowSupport, Storage
if TYPE_CHECKING:
import redis
class RedisInteractor:
RES_DIR = "resources/redis/lua_scripts"
SCRIPT_MOVING_WINDOW = get_package_data(f"{RES_DIR}/moving_window.lua")
SCRIPT_ACQUIRE_MOVING_WINDOW = get_package_data(
f"{RES_DIR}/acquire_moving_window.lua"
)
SCRIPT_CLEAR_KEYS = get_package_data(f"{RES_DIR}/clear_keys.lua")
SCRIPT_INCR_EXPIRE = get_package_data(f"{RES_DIR}/incr_expire.lua")
lua_moving_window: ScriptP[Tuple[int, int]]
lua_acquire_window: ScriptP[bool]
PREFIX = "LIMITS"
def prefixed_key(self, key: str) -> str:
return f"{self.PREFIX}:{key}"
def get_moving_window(self, key: str, limit: int, expiry: int) -> Tuple[int, int]:
"""
returns the starting point and the number of entries in the moving
window
:param key: rate limit key
:param expiry: expiry of entry
:return: (start of window, number of acquired entries)
"""
key = self.prefixed_key(key)
timestamp = time.time()
window = self.lua_moving_window([key], [int(timestamp - expiry), limit])
return window or (int(timestamp), 0)
def _incr(
self,
key: str,
expiry: int,
connection: RedisClient,
elastic_expiry: bool = False,
amount: int = 1,
) -> int:
"""
increments the counter for a given rate limit key
:param connection: Redis connection
:param key: the key to increment
:param expiry: amount in seconds for the key to expire in
:param amount: the number to increment by
"""
key = self.prefixed_key(key)
value = connection.incrby(key, amount)
if elastic_expiry or value == amount:
connection.expire(key, expiry)
return value
def _get(self, key: str, connection: RedisClient) -> int:
"""
:param connection: Redis connection
:param key: the key to get the counter value for
"""
key = self.prefixed_key(key)
return int(connection.get(key) or 0)
def _clear(self, key: str, connection: RedisClient) -> None:
"""
:param key: the key to clear rate limits for
:param connection: Redis connection
"""
key = self.prefixed_key(key)
connection.delete(key)
def _acquire_entry(
self,
key: str,
limit: int,
expiry: int,
connection: RedisClient,
amount: int = 1,
) -> bool:
"""
:param key: rate limit key to acquire an entry in
:param limit: amount of entries allowed
:param expiry: expiry of the entry
:param connection: Redis connection
:param amount: the number of entries to acquire
"""
key = self.prefixed_key(key)
timestamp = time.time()
acquired = self.lua_acquire_window([key], [timestamp, limit, expiry, amount])
return bool(acquired)
def _get_expiry(self, key: str, connection: RedisClient) -> int:
"""
:param key: the key to get the expiry for
:param connection: Redis connection
"""
key = self.prefixed_key(key)
return int(max(connection.ttl(key), 0) + time.time())
def _check(self, connection: RedisClient) -> bool:
"""
:param connection: Redis connection
check if storage is healthy
"""
try:
return connection.ping()
except: # noqa
return False
[docs]
class RedisStorage(RedisInteractor, Storage, MovingWindowSupport):
"""
Rate limit storage with redis as backend.
Depends on :pypi:`redis`.
"""
STORAGE_SCHEME = ["redis", "rediss", "redis+unix"]
"""The storage scheme for redis"""
DEPENDENCIES = {"redis": Version("3.0")}
def __init__(
self,
uri: str,
connection_pool: Optional[redis.connection.ConnectionPool] = None,
wrap_exceptions: bool = False,
**options: Union[float, str, bool],
) -> None:
"""
:param uri: uri of the form ``redis://[:password]@host:port``,
``redis://[:password]@host:port/db``,
``rediss://[:password]@host:port``, ``redis+unix:///path/to/sock`` etc.
This uri is passed directly to :func:`redis.from_url` except for the
case of ``redis+unix://`` where it is replaced with ``unix://``.
:param connection_pool: if provided, the redis client is initialized with
the connection pool and any other params passed as :paramref:`options`
:param wrap_exceptions: Whether to wrap storage exceptions in
:exc:`limits.errors.StorageError` before raising it.
:param options: all remaining keyword arguments are passed
directly to the constructor of :class:`redis.Redis`
:raise ConfigurationError: when the :pypi:`redis` library is not available
"""
super().__init__(uri, wrap_exceptions=wrap_exceptions, **options)
self.dependency = self.dependencies["redis"].module
uri = uri.replace("redis+unix", "unix")
if not connection_pool:
self.storage = self.dependency.from_url(uri, **options)
else:
self.storage = self.dependency.Redis(
connection_pool=connection_pool, **options
)
self.initialize_storage(uri)
@property
def base_exceptions(
self,
) -> Union[Type[Exception], Tuple[Type[Exception], ...]]: # pragma: no cover
return self.dependency.RedisError # type: ignore[no-any-return]
def initialize_storage(self, _uri: str) -> None:
self.lua_moving_window = self.storage.register_script(self.SCRIPT_MOVING_WINDOW)
self.lua_acquire_window = self.storage.register_script(
self.SCRIPT_ACQUIRE_MOVING_WINDOW
)
self.lua_clear_keys = self.storage.register_script(self.SCRIPT_CLEAR_KEYS)
self.lua_incr_expire = self.storage.register_script(
RedisStorage.SCRIPT_INCR_EXPIRE
)
[docs]
def incr(
self, key: str, expiry: int, elastic_expiry: bool = False, amount: int = 1
) -> int:
"""
increments the counter for a given rate limit key
:param key: the key to increment
:param expiry: amount in seconds for the key to expire in
:param amount: the number to increment by
"""
if elastic_expiry:
return super()._incr(key, expiry, self.storage, elastic_expiry, amount)
else:
key = self.prefixed_key(key)
return int(self.lua_incr_expire([key], [expiry, amount]))
[docs]
def get(self, key: str) -> int:
"""
:param key: the key to get the counter value for
"""
return super()._get(key, self.storage)
[docs]
def clear(self, key: str) -> None:
"""
:param key: the key to clear rate limits for
"""
return super()._clear(key, self.storage)
[docs]
def acquire_entry(self, key: str, limit: int, expiry: int, amount: int = 1) -> bool:
"""
:param key: rate limit key to acquire an entry in
:param limit: amount of entries allowed
:param expiry: expiry of the entry
:param amount: the number to increment by
"""
return super()._acquire_entry(key, limit, expiry, self.storage, amount)
[docs]
def get_expiry(self, key: str) -> int:
"""
:param key: the key to get the expiry for
"""
return super()._get_expiry(key, self.storage)
[docs]
def check(self) -> bool:
"""
check if storage is healthy
"""
return super()._check(self.storage)
[docs]
def reset(self) -> Optional[int]:
"""
This function calls a Lua Script to delete keys prefixed with
``self.PREFIX`` in blocks of 5000.
.. warning::
This operation was designed to be fast, but was not tested
on a large production based system. Be careful with its usage as it
could be slow on very large data sets.
"""
prefix = self.prefixed_key("*")
return int(self.lua_clear_keys([prefix]))