380 lines
12 KiB
Python
380 lines
12 KiB
Python
# SPDX-License-Identifier: MIT
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from __future__ import annotations
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import asyncio
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import time
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from collections import deque
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from typing import TYPE_CHECKING, Any, Callable, Deque, Dict, Optional
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from disnake.abc import PrivateChannel
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from disnake.enums import Enum
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from .errors import MaxConcurrencyReached
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if TYPE_CHECKING:
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from typing_extensions import Self
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from ...message import Message
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__all__ = (
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"BucketType",
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"Cooldown",
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"CooldownMapping",
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"DynamicCooldownMapping",
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"MaxConcurrency",
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)
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class BucketType(Enum):
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default = 0
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user = 1
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guild = 2
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channel = 3
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member = 4
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category = 5
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role = 6
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def get_key(self, msg: Message) -> Any:
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if self is BucketType.user:
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return msg.author.id
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elif self is BucketType.guild:
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return (msg.guild or msg.author).id
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elif self is BucketType.channel:
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return msg.channel.id
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elif self is BucketType.member:
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return ((msg.guild and msg.guild.id), msg.author.id)
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elif self is BucketType.category:
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return (msg.channel.category or msg.channel).id # type: ignore
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elif self is BucketType.role:
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# we return the channel id of a private-channel as there are only roles in guilds
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# and that yields the same result as for a guild with only the @everyone role
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# NOTE: PrivateChannel doesn't actually have an id attribute but we assume we are
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# recieving a DMChannel or GroupChannel which inherit from PrivateChannel and do
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return (msg.channel if isinstance(msg.channel, PrivateChannel) else msg.author.top_role).id # type: ignore
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def __call__(self, msg: Message) -> Any:
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return self.get_key(msg)
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class Cooldown:
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"""Represents a cooldown for a command.
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Attributes
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----------
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rate: :class:`int`
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The total number of tokens available per :attr:`per` seconds.
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per: :class:`float`
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The length of the cooldown period in seconds.
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"""
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__slots__ = ("rate", "per", "_window", "_tokens", "_last")
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def __init__(self, rate: float, per: float) -> None:
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self.rate: int = int(rate)
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self.per: float = float(per)
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self._window: float = 0.0
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self._tokens: int = self.rate
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self._last: float = 0.0
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def get_tokens(self, current: Optional[float] = None) -> int:
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"""Returns the number of available tokens before rate limiting is applied.
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Parameters
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----------
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current: Optional[:class:`float`]
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The time in seconds since Unix epoch to calculate tokens at.
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If not supplied then :func:`time.time()` is used.
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Returns
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-------
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:class:`int`
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The number of tokens available before the cooldown is to be applied.
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"""
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if not current:
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current = time.time()
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tokens = self._tokens
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if current > self._window + self.per:
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tokens = self.rate
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return tokens
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def get_retry_after(self, current: Optional[float] = None) -> float:
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"""Returns the time in seconds until the cooldown will be reset.
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Parameters
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----------
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current: Optional[:class:`float`]
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The current time in seconds since Unix epoch.
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If not supplied, then :func:`time.time()` is used.
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Returns
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-------
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:class:`float`
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The number of seconds to wait before this cooldown will be reset.
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"""
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current = current or time.time()
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tokens = self.get_tokens(current)
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if tokens == 0:
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return self.per - (current - self._window)
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return 0.0
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def update_rate_limit(self, current: Optional[float] = None) -> Optional[float]:
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"""Updates the cooldown rate limit.
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Parameters
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----------
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current: Optional[:class:`float`]
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The time in seconds since Unix epoch to update the rate limit at.
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If not supplied, then :func:`time.time()` is used.
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Returns
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-------
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Optional[:class:`float`]
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The retry-after time in seconds if rate limited.
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"""
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current = current or time.time()
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self._last = current
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self._tokens = self.get_tokens(current)
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# first token used means that we start a new rate limit window
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if self._tokens == self.rate:
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self._window = current
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# check if we are rate limited
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if self._tokens == 0:
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return self.per - (current - self._window)
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# we're not so decrement our tokens
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self._tokens -= 1
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def reset(self) -> None:
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"""Reset the cooldown to its initial state."""
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self._tokens = self.rate
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self._last = 0.0
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def copy(self) -> Cooldown:
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"""Creates a copy of this cooldown.
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Returns
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-------
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:class:`Cooldown`
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A new instance of this cooldown.
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"""
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return Cooldown(self.rate, self.per)
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def __repr__(self) -> str:
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return f"<Cooldown rate: {self.rate} per: {self.per} window: {self._window} tokens: {self._tokens}>"
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class CooldownMapping:
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def __init__(
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self,
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original: Optional[Cooldown],
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type: Callable[[Message], Any],
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) -> None:
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if not callable(type):
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raise TypeError("Cooldown type must be a BucketType or callable")
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self._cache: Dict[Any, Cooldown] = {}
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self._cooldown: Optional[Cooldown] = original
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self._type: Callable[[Message], Any] = type
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def copy(self) -> CooldownMapping:
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ret = CooldownMapping(self._cooldown, self._type)
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ret._cache = self._cache.copy()
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return ret
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@property
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def valid(self) -> bool:
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return self._cooldown is not None
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@property
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def type(self) -> Callable[[Message], Any]:
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return self._type
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@classmethod
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def from_cooldown(cls, rate: float, per: float, type) -> Self:
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return cls(Cooldown(rate, per), type)
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def _bucket_key(self, msg: Message) -> Any:
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return self._type(msg)
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def _verify_cache_integrity(self, current: Optional[float] = None) -> None:
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# we want to delete all cache objects that haven't been used
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# in a cooldown window. e.g. if we have a command that has a
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# cooldown of 60s and it has not been used in 60s then that key should be deleted
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current = current or time.time()
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dead_keys = [k for k, v in self._cache.items() if current > v._last + v.per]
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for k in dead_keys:
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del self._cache[k]
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def _is_default(self) -> bool:
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# This method can be overridden in subclasses
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return self._type is BucketType.default
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def create_bucket(self, message: Message) -> Cooldown:
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return self._cooldown.copy() # type: ignore
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def get_bucket(self, message: Message, current: Optional[float] = None) -> Cooldown:
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if self._is_default():
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return self._cooldown # type: ignore
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self._verify_cache_integrity(current)
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key = self._bucket_key(message)
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if key not in self._cache:
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bucket = self.create_bucket(message)
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if bucket is not None:
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self._cache[key] = bucket
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else:
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bucket = self._cache[key]
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return bucket
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def update_rate_limit(
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self, message: Message, current: Optional[float] = None
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) -> Optional[float]:
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bucket = self.get_bucket(message, current)
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return bucket.update_rate_limit(current)
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class DynamicCooldownMapping(CooldownMapping):
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def __init__(
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self, factory: Callable[[Message], Cooldown], type: Callable[[Message], Any]
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) -> None:
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super().__init__(None, type)
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self._factory: Callable[[Message], Cooldown] = factory
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def copy(self) -> DynamicCooldownMapping:
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ret = DynamicCooldownMapping(self._factory, self._type)
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ret._cache = self._cache.copy()
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return ret
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@property
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def valid(self) -> bool:
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return True
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def _is_default(self) -> bool:
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# In dynamic mappings even default bucket types may have custom behavior
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return False
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def create_bucket(self, message: Message) -> Cooldown:
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return self._factory(message)
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class _Semaphore:
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"""A custom version of a semaphore.
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If you're wondering why asyncio.Semaphore isn't being used,
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it's because it doesn't expose the internal value. This internal
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value is necessary because I need to support both `wait=True` and
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`wait=False`.
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An asyncio.Queue could have been used to do this as well -- but it is
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not as inefficient since internally that uses two queues and is a bit
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overkill for what is basically a counter.
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"""
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__slots__ = ("value", "loop", "_waiters")
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def __init__(self, number: int) -> None:
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self.value: int = number
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self.loop: asyncio.AbstractEventLoop = asyncio.get_running_loop()
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self._waiters: Deque[asyncio.Future] = deque()
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def __repr__(self) -> str:
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return f"<_Semaphore value={self.value} waiters={len(self._waiters)}>"
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def locked(self) -> bool:
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return self.value == 0
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def is_active(self) -> bool:
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return len(self._waiters) > 0
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def wake_up(self) -> None:
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while self._waiters:
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future = self._waiters.popleft()
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if not future.done():
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future.set_result(None)
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return
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async def acquire(self, *, wait: bool = False) -> bool:
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if not wait and self.value <= 0:
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# signal that we're not acquiring
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return False
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while self.value <= 0:
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future = self.loop.create_future()
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self._waiters.append(future)
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try:
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await future
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except Exception:
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future.cancel()
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if self.value > 0 and not future.cancelled():
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self.wake_up()
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raise
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self.value -= 1
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return True
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def release(self) -> None:
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self.value += 1
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self.wake_up()
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class MaxConcurrency:
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__slots__ = ("number", "per", "wait", "_mapping")
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def __init__(self, number: int, *, per: BucketType, wait: bool) -> None:
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self._mapping: Dict[Any, _Semaphore] = {}
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self.per: BucketType = per
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self.number: int = number
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self.wait: bool = wait
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if number <= 0:
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raise ValueError("max_concurrency 'number' cannot be less than 1")
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if not isinstance(per, BucketType):
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raise TypeError(f"max_concurrency 'per' must be of type BucketType not {type(per)!r}")
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def copy(self) -> Self:
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return self.__class__(self.number, per=self.per, wait=self.wait)
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def __repr__(self) -> str:
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return f"<MaxConcurrency per={self.per!r} number={self.number} wait={self.wait}>"
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def get_key(self, message: Message) -> Any:
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return self.per.get_key(message)
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async def acquire(self, message: Message) -> None:
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key = self.get_key(message)
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try:
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sem = self._mapping[key]
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except KeyError:
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self._mapping[key] = sem = _Semaphore(self.number)
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acquired = await sem.acquire(wait=self.wait)
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if not acquired:
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raise MaxConcurrencyReached(self.number, self.per)
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async def release(self, message: Message) -> None:
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# Technically there's no reason for this function to be async
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# But it might be more useful in the future
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key = self.get_key(message)
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try:
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sem = self._mapping[key]
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except KeyError:
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# ...? peculiar
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return
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else:
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sem.release()
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if sem.value >= self.number and not sem.is_active():
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del self._mapping[key]
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