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fawney19
431
src/plugins/rate_limit/token_bucket.py
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431
src/plugins/rate_limit/token_bucket.py
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"""令牌桶速率限制策略，支持 Redis 分布式后端"""
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import asyncio
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import os
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import time
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from datetime import datetime, timedelta
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from typing import Any, Dict, Optional, Tuple
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from ...clients.redis_client import get_redis_client_sync
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from src.core.logger import logger
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from .base import RateLimitResult, RateLimitStrategy
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class TokenBucket:
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"""令牌桶实现"""
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def __init__(self, capacity: int, refill_rate: float):
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"""
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初始化令牌桶
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Args:
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capacity: 桶容量（最大令牌数）
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refill_rate: 令牌补充速率（每秒）
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"""
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self.capacity = capacity
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self.refill_rate = refill_rate
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self.tokens = capacity
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self.last_refill = time.time()
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def _refill(self):
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"""补充令牌"""
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now = time.time()
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time_passed = now - self.last_refill
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tokens_to_add = time_passed * self.refill_rate
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if tokens_to_add > 0:
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self.tokens = min(self.capacity, self.tokens + tokens_to_add)
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self.last_refill = now
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def consume(self, amount: int = 1) -> bool:
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"""
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消费令牌
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Args:
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amount: 要消费的令牌数
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Returns:
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是否成功消费
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"""
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self._refill()
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if self.tokens >= amount:
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self.tokens -= amount
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return True
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return False
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def get_remaining(self) -> int:
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"""获取剩余令牌数"""
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self._refill()
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return int(self.tokens)
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def get_reset_time(self) -> datetime:
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"""获取下次完全恢复的时间"""
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if self.tokens >= self.capacity:
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return datetime.now()
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tokens_needed = self.capacity - self.tokens
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seconds_to_full = tokens_needed / self.refill_rate
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return datetime.now() + timedelta(seconds=seconds_to_full)
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class TokenBucketStrategy(RateLimitStrategy):
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"""
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令牌桶算法速率限制策略
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特点：
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- 允许突发流量
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- 平均速率受限
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- 适合处理不均匀的流量模式
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"""
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def __init__(self):
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super().__init__("token_bucket")
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self.buckets: Dict[str, TokenBucket] = {}
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self._lock = asyncio.Lock()
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# 默认配置
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self.default_capacity = 100 # 默认桶容量
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self.default_refill_rate = 10 # 默认每秒补充10个令牌
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# 可选的 Redis 后端
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self._redis_backend: Optional[RedisTokenBucketBackend] = None
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self._redis_checked = False
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self._backend_mode = os.getenv("RATE_LIMIT_BACKEND", "auto").lower()
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def _get_bucket(self, key: str, rate_limit: Optional[int] = None) -> TokenBucket:
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"""
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获取或创建令牌桶
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Args:
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key: 限制键
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rate_limit: 每分钟请求限制（来自数据库配置），如果提供则使用此值
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Returns:
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令牌桶实例
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"""
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if key not in self.buckets:
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# 如果提供了rate_limit参数（来自数据库），优先使用
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if rate_limit is not None:
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# rate_limit 是每分钟请求数，转换为令牌桶参数
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capacity = rate_limit # 桶容量等于每分钟限制
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refill_rate = rate_limit / 60.0 # 每秒补充的令牌数
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# 否则根据key的不同前缀使用不同的配置
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elif key.startswith("api_key:"):
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capacity = self.config.get("api_key_capacity", self.default_capacity)
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refill_rate = self.config.get("api_key_refill_rate", self.default_refill_rate)
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elif key.startswith("user:"):
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capacity = self.config.get("user_capacity", self.default_capacity * 2)
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refill_rate = self.config.get("user_refill_rate", self.default_refill_rate * 2)
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else:
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capacity = self.default_capacity
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refill_rate = self.default_refill_rate
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self.buckets[key] = TokenBucket(capacity, refill_rate)
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return self.buckets[key]
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def _want_redis_backend(self) -> bool:
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return self._backend_mode in {"auto", "redis"}
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async def _ensure_backend(self):
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if self._redis_checked:
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return
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self._redis_checked = True
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if not self._want_redis_backend():
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return
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redis_client = get_redis_client_sync()
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if redis_client:
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self._redis_backend = RedisTokenBucketBackend(redis_client)
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logger.info("速率限制改用 Redis 令牌桶后端")
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elif self._backend_mode == "redis":
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logger.warning("RATE_LIMIT_BACKEND=redis 但 Redis 客户端不可用，回退到内存桶")
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async def check_limit(self, key: str, **kwargs) -> RateLimitResult:
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"""
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检查速率限制
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Args:
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key: 限制键
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**kwargs: 额外参数，包括 rate_limit (从数据库配置)
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Returns:
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速率限制检查结果
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"""
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await self._ensure_backend()
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rate_limit = kwargs.get("rate_limit")
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amount = kwargs.get("amount", 1)
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if self._redis_backend:
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return await self._redis_backend.peek(
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key=key,
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capacity=self._resolve_capacity(key, rate_limit),
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refill_rate=self._resolve_refill_rate(key, rate_limit),
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amount=amount,
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)
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async with self._lock:
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bucket = self._get_bucket(key, rate_limit)
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remaining = bucket.get_remaining()
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reset_at = bucket.get_reset_time()
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allowed = remaining >= amount
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retry_after = None
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if not allowed:
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tokens_needed = amount - remaining
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retry_after = int(tokens_needed / bucket.refill_rate) + 1
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return RateLimitResult(
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allowed=allowed,
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remaining=remaining,
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reset_at=reset_at,
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retry_after=retry_after,
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message=(
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None
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if allowed
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else f"Rate limit exceeded. Please retry after {retry_after} seconds."
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),
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)
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async def consume(self, key: str, amount: int = 1, **kwargs) -> bool:
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"""
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消费令牌
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Args:
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key: 限制键
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amount: 消费数量
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Returns:
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是否成功消费
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"""
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await self._ensure_backend()
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if self._redis_backend:
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success, remaining = await self._redis_backend.consume(
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key=key,
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capacity=self._resolve_capacity(key, kwargs.get("rate_limit")),
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refill_rate=self._resolve_refill_rate(key, kwargs.get("rate_limit")),
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amount=amount,
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)
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if success:
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logger.debug("Redis 令牌消费成功")
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else:
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logger.warning("Redis 令牌消费失败")
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return success
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async with self._lock:
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bucket = self._get_bucket(key)
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success = bucket.consume(amount)
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if success:
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logger.debug(f"令牌消费成功")
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else:
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logger.warning(f"令牌消费失败：超出速率限制")
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return success
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async def reset(self, key: str):
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"""
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重置令牌桶
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Args:
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key: 限制键
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"""
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await self._ensure_backend()
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if self._redis_backend:
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await self._redis_backend.reset(key)
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return
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async with self._lock:
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if key in self.buckets:
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bucket = self.buckets[key]
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bucket.tokens = bucket.capacity
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bucket.last_refill = time.time()
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logger.info(f"令牌桶已重置")
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async def get_stats(self, key: str) -> Dict[str, Any]:
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"""
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获取统计信息
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Args:
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key: 限制键
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Returns:
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统计信息
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"""
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await self._ensure_backend()
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if self._redis_backend:
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return await self._redis_backend.get_stats(
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key,
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capacity=self._resolve_capacity(key),
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refill_rate=self._resolve_refill_rate(key),
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)
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async with self._lock:
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bucket = self._get_bucket(key)
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return {
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"strategy": "token_bucket",
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"key": key,
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"capacity": bucket.capacity,
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"remaining": bucket.get_remaining(),
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"refill_rate": bucket.refill_rate,
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"reset_at": bucket.get_reset_time().isoformat(),
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}
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def configure(self, config: Dict[str, Any]):
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"""
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配置策略
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支持的配置项：
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- api_key_capacity: API Key的桶容量
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- api_key_refill_rate: API Key的令牌补充速率
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- user_capacity: 用户的桶容量
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- user_refill_rate: 用户的令牌补充速率
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"""
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super().configure(config)
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self.default_capacity = config.get("default_capacity", self.default_capacity)
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self.default_refill_rate = config.get("default_refill_rate", self.default_refill_rate)
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def _resolve_capacity(self, key: str, rate_limit: Optional[int] = None) -> int:
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if rate_limit is not None:
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return rate_limit
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if key.startswith("api_key:"):
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return self.config.get("api_key_capacity", self.default_capacity)
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if key.startswith("user:"):
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return self.config.get("user_capacity", self.default_capacity * 2)
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return self.default_capacity
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def _resolve_refill_rate(self, key: str, rate_limit: Optional[int] = None) -> float:
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if rate_limit is not None:
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return rate_limit / 60.0
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if key.startswith("api_key:"):
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return self.config.get("api_key_refill_rate", self.default_refill_rate)
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if key.startswith("user:"):
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return self.config.get("user_refill_rate", self.default_refill_rate * 2)
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return self.default_refill_rate
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class RedisTokenBucketBackend:
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"""使用 Redis 存储令牌桶状态，支持多实例共享"""
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_SCRIPT = """
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local key = KEYS[1]
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local now = tonumber(ARGV[1])
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local capacity = tonumber(ARGV[2])
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local refill_rate = tonumber(ARGV[3])
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local amount = tonumber(ARGV[4])
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local data = redis.call('HMGET', key, 'tokens', 'timestamp')
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local tokens = tonumber(data[1])
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local last_refill = tonumber(data[2])
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if tokens == nil then
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tokens = capacity
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last_refill = now
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end
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local delta = math.max(0, now - last_refill)
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local refill = delta * refill_rate
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tokens = math.min(capacity, tokens + refill)
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local allowed = 0
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local retry_after = 0
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if tokens >= amount then
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tokens = tokens - amount
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allowed = 1
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else
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retry_after = math.ceil((amount - tokens) / refill_rate)
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end
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redis.call('HMSET', key, 'tokens', tokens, 'timestamp', now)
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local ttl = math.max(1, math.ceil(capacity / refill_rate))
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redis.call('EXPIRE', key, ttl)
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return {allowed, tokens, retry_after}
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"""
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def __init__(self, redis_client):
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self.redis = redis_client
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self._consume_script = self.redis.register_script(self._SCRIPT)
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def _redis_key(self, key: str) -> str:
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return f"rate_limit:bucket:{key}"
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async def peek(
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self,
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key: str,
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capacity: int,
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refill_rate: float,
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amount: int,
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) -> RateLimitResult:
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bucket_key = self._redis_key(key)
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data = await self.redis.hmget(bucket_key, "tokens", "timestamp")
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tokens = data[0]
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last_refill = data[1]
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if tokens is None or last_refill is None:
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remaining = capacity
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reset_at = datetime.now() + timedelta(seconds=capacity / refill_rate)
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else:
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tokens_value = float(tokens)
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last_refill_value = float(last_refill)
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delta = max(0.0, time.time() - last_refill_value)
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tokens_value = min(capacity, tokens_value + delta * refill_rate)
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remaining = int(tokens_value)
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reset_after = 0 if tokens_value >= capacity else (capacity - tokens_value) / refill_rate
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reset_at = datetime.now() + timedelta(seconds=reset_after)
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allowed = remaining >= amount
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retry_after = None
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if not allowed:
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needed = max(0, amount - remaining)
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retry_after = int(needed / refill_rate) + 1
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return RateLimitResult(
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allowed=allowed,
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remaining=int(remaining),
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reset_at=reset_at,
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retry_after=retry_after,
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message=(
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None
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if allowed
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else f"Rate limit exceeded. Please retry after {retry_after} seconds."
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),
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)
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async def consume(
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self,
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key: str,
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capacity: int,
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refill_rate: float,
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amount: int,
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) -> Tuple[bool, int]:
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result = await self._consume_script(
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keys=[self._redis_key(key)],
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args=[time.time(), capacity, refill_rate, amount],
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)
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allowed = bool(result[0])
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remaining = int(float(result[1]))
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return allowed, remaining
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async def reset(self, key: str):
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await self.redis.delete(self._redis_key(key))
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async def get_stats(self, key: str, capacity: int, refill_rate: float) -> Dict[str, Any]:
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data = await self.redis.hmget(self._redis_key(key), "tokens", "timestamp")
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tokens = data[0]
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timestamp = data[1]
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return {
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"strategy": "token_bucket",
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"key": key,
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"capacity": capacity,
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"remaining": float(tokens) if tokens else capacity,
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"refill_rate": refill_rate,
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"last_refill": float(timestamp) if timestamp else time.time(),
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"backend": "redis",
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}
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