feat(middleware): 添加慢请求监控中间件

添加 SlowRequestMiddleware 用于监控并记录超过阈值的慢请求

fastapi/applications.py

@@ -13,6 +13,7 @@ from fastapi.exception_handlers import (
 from fastapi.exceptions import RequestValidationError, WebSocketRequestValidationError
 from fastapi.logger import logger
 from fastapi.middleware.asyncexitstack import AsyncExitStackMiddleware
+from fastapi.middleware.slow_request import SlowRequestMiddleware
 from fastapi.openapi.docs import (
     get_redoc_html,
     get_swagger_ui_html,
@@ -1029,7 +1030,8 @@ class FastAPI(Starlette):
                 exception_handlers[key] = value
 
         middleware = (
-            [Middleware(ServerErrorMiddleware, handler=error_handler, debug=debug)]  # ty: ignore[invalid-argument-type]
+            [Middleware(SlowRequestMiddleware)]
+            + [Middleware(ServerErrorMiddleware, handler=error_handler, debug=debug)]  # ty: ignore[invalid-argument-type]
             + self.user_middleware
             + [
                 Middleware(

fastapi/middleware/__init__.py

@@ -1 +1,3 @@
 from starlette.middleware import Middleware as Middleware
+
+from fastapi.middleware.slow_request import SlowRequestMiddleware

fastapi/middleware/slow_request.py

@@ -0,0 +1,51 @@
+import logging
+import time
+
+from starlette.middleware.base import BaseHTTPMiddleware
+from starlette.requests import Request
+from starlette.responses import Response
+from starlette.types import ASGIApp
+
+logger = logging.getLogger("fastapi")
+
+
+class SlowRequestMiddleware(BaseHTTPMiddleware):
+    """
+    Middleware to monitor slow requests and log warnings when they exceed the threshold.
+    """
+
+    def __init__(self, app: ASGIApp, threshold: float = 0.5) -> None:
+        """
+        Initialize the SlowRequestMiddleware.
+
+        Args:
+            app: The ASGI application.
+            threshold: The threshold in seconds for considering a request as slow.
+                Defaults to 0.5 seconds (500ms).
+        """
+        super().__init__(app)
+        self.threshold = threshold
+
+    async def dispatch(self, request: Request, call_next) -> Response:
+        """
+        Dispatch the request, measuring the time taken.
+
+        Args:
+            request: The incoming request.
+            call_next: The next middleware or endpoint handler.
+
+        Returns:
+            The response from the next middleware or endpoint handler.
+        """
+        start_time = time.perf_counter()
+        try:
+            response = await call_next(request)
+            return response
+        finally:
+            duration = time.perf_counter() - start_time
+            if duration > self.threshold:
+                method = request.method
+                url = str(request.url)
+                logger.warning(
+                    f"Slow request: {method} {url} took {duration:.2f}s (threshold: {self.threshold:.2f}s)"
+                )

tests/test_slow_request_middleware.py

@@ -0,0 +1,53 @@
+import asyncio
+import logging
+import time
+
+from fastapi import FastAPI
+from fastapi.testclient import TestClient
+
+app = FastAPI()
+
+
+@app.get("/fast")
+async def fast_endpoint():
+    return {"message": "Fast response"}
+
+
+@app.get("/slow")
+async def slow_endpoint():
+    await asyncio.sleep(0.6)
+    return {"message": "Slow response"}
+
+
+def test_slow_request_logging(caplog):
+    caplog.set_level(logging.WARNING)
+    client = TestClient(app)
+
+    # 测试快速请求，不应记录警告
+    response = client.get("/fast")
+    assert response.status_code == 200
+    assert "Slow request" not in caplog.text
+
+    # 测试慢速请求，应记录警告
+    response = client.get("/slow")
+    assert response.status_code == 200
+
+    # 检查日志是否包含预期的警告信息
+    slow_request_logs = [record for record in caplog.records if "Slow request" in record.message]
+    assert len(slow_request_logs) == 1
+
+    log_message = slow_request_logs[0].message
+    assert "GET" in log_message
+    assert "/slow" in log_message
+    # 检查是否包含两位小数的时间
+    import re
+    match = re.search(r"took (\d+\.\d{2})s", log_message)
+    assert match is not None, f"Log message should contain time with two decimal places: {log_message}"
+
+    print("✅ 慢请求监控中间件测试通过！")
+    print(f"   日志消息: {log_message}")
+
+
+if __name__ == "__main__":
+    import pytest
+    pytest.main([__file__, "-v", "-s"])