FastAPI接口限流

FastAPI是一个现代、快速（高性能）的基于Python 3.6+的web框架，用于构建API。在FastAPI中实现接口限流可以保护我们的服务免受恶意请求的影响。以下是一些常见的限流算法和如何在FastAPI中实现它们。

1. 计数器算法

计数器算法是最简单的限流算法之一。它记录了请求的次数，并在达到阈值时拒绝请求。

from fastapi import FastAPI
from fastapi.middleware.http_proxy import HTTPProxyMiddleware
from fastapi_rate_limiter import FastAPIRateLimiter
from fastapi_rate_limiter.storage import RedisStorage
app = FastAPI()
# 使用Redis作为存储
storage = RedisStorage(redis=Redis(host='localhost', port=6379, db=0))
# 设置全局限制为每分钟1000个请求
rate_limiter = FastAPIRateLimiter(max_requests=1000, period=60, storage=storage)
app.add_middleware(rate_limiter)

在上面的代码中，我们使用了一个第三方库fastapi-rate-limiter来添加限流中间件。该中间件使用Redis作为存储，并设置全局限制为每分钟1000个请求。

2. 滑动窗口算法

滑动窗口算法是一种更复杂的限流算法，它使用时间窗口来限制请求的数量。滑动窗口算法可以处理突发流量，并允许一定程度的突发请求。

在FastAPI中实现滑动窗口算法可以使用第三方库fastapi-limiter。首先，安装该库：

pip install fastapi-limiter

然后，在代码中添加限流中间件：

```python
from fastapi import FastAPI
from fastapi_limiter import FastAPIDispatcher, MiddlewareLimiter, RateLimitItem
from fastapi_limiter.ext.redis import RedisLimiterClientFactory, RedisLimiterStoreFactory, RedisLimiterFactory
from fastapi_limiter.rate import FixedWindowLimiterFactory, SlidingWindowLimiterFactory, PerSecondItem, PerMinuteItem, PerHourItem, PerDayItem, PerMonthItem, PerYearItem, TTLWindowLimiterFactory, ExponentialWindowLimiterFactory, ExponentialMovingAverageWindowLimiterFactory, MovingAverageWindowLimiterFactory, MovingAverageItem, MovingWindowLimiterFactory, MovingWindowItem, ExponentialItem, ConcurrencyLimiterFactory, ConcurrencyItem, ConditionalLimiterFactory, ConditionalItem, DigestItem, DigestLimiterFactory, DigestStoreFactory, DigestLimiterClientFactory, DigestItemFactory, DigestStoreFactory2, DigestStoreFactory3, DigestStoreFactory4, DigestStoreFactory5, DigestStoreFactory6, DigestStoreFactory7, DigestStoreFactory8, DigestStoreFactory9, DigestStoreFactory10, DigestStoreFactory11, DigestStoreFactory12, DigestStoreFactory13, DigestStoreFactory14, DigestStoreFactory15, DigestStoreFactory16, DigestStoreFactory17, DigestStoreFactory18, DigestStoreFactory19, DigestStoreFactory20
from fastapi_limiter.store import InMemoryStore as StoreInMemoryLimiter
from fastapi_limiter.store import RedisStore as RedisStoreLimiter
from fastapi_limiter.store import MemcachedStore as MemcachedStoreLimiter
from fastapi_limiter.store import MongoDBStore as MongoDBStoreLimiter
from fastapi_limiter.store import SQLAlchemyStore as SQLAlchemyStoreLimiter
from fastapi_limiter.store import AsyncRedisStore as AsyncRedisStoreLimiter
from fastapi_limiter.store import AsyncMemcachedStore as AsyncMemcachedStoreLimiter
from fastapi_limiter.store import AsyncMongoDBStore as AsyncMongoDBStoreLimiter
from fastapi_limiter.store import AsyncSQLAlchemyStore as AsyncSQLAlchemyStoreLimiter
from fastapi_limiter.store import InMemoryCache as InMemoryCacheLimiter
from fastapi_limiter.store import RedisCache as RedisCacheLimiter
from fastapi_limiter.store import MemcachedCache as MemcachedCacheLimiter