test: add pyinstrument profiler (#3955)

lnbits/middleware.py

@@ -7,6 +7,7 @@ from typing import Any
 from fastapi import FastAPI, Request, Response
 from fastapi.responses import HTMLResponse, JSONResponse, RedirectResponse
 from loguru import logger
+from pyinstrument import Profiler
 from slowapi import _rate_limit_exceeded_handler
 from slowapi.errors import RateLimitExceeded
 from slowapi.middleware import SlowAPIMiddleware
@@ -246,3 +247,16 @@ def add_first_install_middleware(app: FastAPI):
         ):
             return RedirectResponse("/first_install")
         return await call_next(request)
+
+
+def add_profiler_middleware(app: FastAPI):
+    @app.middleware("http")
+    async def profile_middleware(request: Request, call_next):
+        profiling = request.query_params.get("profiler", False)
+        if profiling:
+            profiler = Profiler(async_mode="enabled")
+            profiler.start()
+            _ = await call_next(request)
+            profiler.stop()
+            return HTMLResponse(profiler.output_html())
+        return await call_next(request)