perf: use singleton httpx client to reduce RAM usage

main.py

@@ -1,13 +1,24 @@
 from fastapi import FastAPI, Request, Response, HTTPException
 from fastapi.middleware.cors import CORSMiddleware
 import httpx
-import asyncio
-
-app = FastAPI()
+from contextlib import asynccontextmanager
 
 # The target Azure VM backend URL
 TARGET_URL = "https://snap-providers-mercy-protocol.trycloudflare.com"
 
+# Use a global client to avoid creating a new one for every request (reduces RAM/CPU overhead)
+client_state = {}
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    # Initialize the client on startup
+    client_state["client"] = httpx.AsyncClient(timeout=60.0)
+    yield
+    # Close the client on shutdown
+    await client_state["client"].aclose()
+
+app = FastAPI(lifespan=lifespan)
+
 app.add_middleware(
     CORSMiddleware,
     allow_origins=["*"],
@@ -17,34 +28,33 @@ app.add_middleware(
 
 @app.api_route("/{path:path}", methods=["GET", "POST", "PUT", "DELETE", "OPTIONS"])
 async def proxy(request: Request, path: str):
-    """Forwards all requests to the target backend."""
+    \"\"\"Forwards all requests to the target backend.\"\"\"
     url = f"{TARGET_URL}/{path}"
     
     if request.method == "OPTIONS":
         return Response(status_code=200)
 
-    async with httpx.AsyncClient() as client:
-        body = await request.body()
-        headers = dict(request.headers)
-        headers.pop("host", None)
+    client = client_state["client"]
+    body = await request.body()
+    headers = dict(request.headers)
+    headers.pop("host", None)
+    
+    try:
+        resp = await client.request(
+            method=request.method,
+            url=url,
+            headers=headers,
+            content=body
+        )
         
-        try:
-            resp = await client.request(
-                method=request.method,
-                url=url,
-                headers=headers,
-                content=body,
-                timeout=60.0
-            )
-            
-            # Return the original response from the backend
-            return Response(
-                content=resp.content,
-                status_code=resp.status_code,
-                headers=dict(resp.headers)
-            )
-        except httpx.RequestError as e:
-            raise HTTPException(status_code=502, detail=f"Proxy Error: {str(e)}")
+        return Response(
+            content=resp.content,
+            status_code=resp.status_code,
+            headers=dict(resp.headers)
+        )
+    except httpx.RequestError as e:
+        raise HTTPException(status_code=502, detail=f"Proxy Error: {str(e)}")
+
 
 if __name__ == "__main__":
     import uvicorn