Update app.py

app.py

@@ -1,33 +1,43 @@
-from fastapi import FastAPI
-from fastapi.responses import HTMLResponse
-from fastapi.staticfiles import StaticFiles
-import subprocess
-import json
-
-app = FastAPI()
-
-# Mount frontend directory for static assets
-app.mount("/frontend", StaticFiles(directory="frontend"), name="frontend")
-
-@app.get("/", response_class=HTMLResponse)
-async def root():
-    with open("frontend/index.html", "r") as f:
-        return f.read()
-
-@app.get("/api/benchmark")
-async def run_benchmark(orders: int = 1000000, cancel: float = 0.20, market: float = 0.10):
-    cmd = [
-        "./build/benchmark", 
-        "--orders", str(orders), 
-        "--cancel-ratio", str(cancel), 
-        "--market-ratio", str(market), 
-        "--json", 
-        "--quiet"
-    ]
-    
-    try:
-        # Executing the real C++ binary
-        result = subprocess.run(cmd, capture_output=True, text=True, check=True)
-        return json.loads(result.stdout)
-    except Exception as e:
-        return {"error": str(e)}
+from fastapi import FastAPI
+from fastapi.responses import HTMLResponse
+from fastapi.staticfiles import StaticFiles
+import asyncio
+import json
+
+app = FastAPI()
+
+app.mount("/frontend", StaticFiles(directory="frontend"), name="frontend")
+
+@app.get("/", response_class=HTMLResponse)
+async def root():
+    with open("frontend/index.html", "r") as f:
+        return f.read()
+
+@app.get("/api/benchmark")
+async def run_benchmark(orders: int = 1000000, cancel: float = 0.20, market: float = 0.10):
+    cmd = [
+        "./build/benchmark", 
+        "--orders", str(orders), 
+        "--cancel-ratio", str(cancel), 
+        "--market-ratio", str(market), 
+        "--json", 
+        "--quiet"
+    ]
+    
+    try:
+        # BUG 4 FIXED: Using non-blocking asyncio subprocess
+        process = await asyncio.create_subprocess_exec(
+            *cmd,
+            stdout=asyncio.subprocess.PIPE,
+            stderr=asyncio.subprocess.PIPE
+        )
+        stdout, stderr = await process.communicate()
+        
+        if process.returncode != 0:
+            return {"error": f"C++ Binary Crashed (Code {process.returncode}). Stderr: {stderr.decode()}"}
+            
+        return json.loads(stdout.decode())
+    except json.JSONDecodeError:
+        return {"error": f"Invalid JSON output from C++: {stdout.decode()}"}
+    except Exception as e:
+        return {"error": f"Server execution error: {str(e)}"}