stable_web_launcher.py

#!/usr/bin/env python3
"""
Stable Web Demo Launcher
Ensures the Streamlit server stays running reliably
"""
import subprocess
import sys
import time
import os
import signal
from pathlib import Path

class WebDemoLauncher:
    def __init__(self):
        self.process = None
        self.running = False
        
    def cleanup(self, signum=None, frame=None):
        """Clean shutdown"""
        print("\n🛑 Shutting down web demo...")
        self.running = False
        if self.process:
            try:
                self.process.terminate()
                self.process.wait(timeout=5)
            except:
                if self.process:
                    self.process.kill()
        print("✅ Web demo stopped cleanly")
        sys.exit(0)
    
    def start_server(self, port=8507):
        """Start Streamlit server with error handling"""
        cmd = [
            sys.executable, "-m", "streamlit", "run", "web_demo.py",
            "--server.port", str(port),
            "--server.address", "0.0.0.0",
            "--server.headless", "true",
            "--browser.gatherUsageStats", "false",
            "--server.enableCORS", "false",
            "--server.enableXsrfProtection", "false"
        ]
        
        try:
            self.process = subprocess.Popen(
                cmd,
                stdout=subprocess.PIPE,
                stderr=subprocess.STDOUT,
                universal_newlines=True,
                bufsize=1
            )
            return True
        except Exception as e:
            print(f"❌ Failed to start server: {e}")
            return False
    
    def monitor_server(self, port=8507):
        """Monitor server and restart if needed"""
        print("🚀 Starting Pandas-TA Web Demo")
        print("=" * 40)
        print(f"📱 Local URL: http://localhost:{port}")
        print(f"📱 Network URL: http://10.0.0.214:{port}")
        print("🔄 Server will auto-restart if it crashes")
        print("⏹️  Press Ctrl+C to stop")
        print("=" * 40)
        
        # Set up signal handlers
        signal.signal(signal.SIGINT, self.cleanup)
        signal.signal(signal.SIGTERM, self.cleanup)
        
        self.running = True
        restart_count = 0
        
        while self.running:
            if not self.start_server(port):
                time.sleep(5)
                continue
                
            print(f"✅ Web demo started (attempt #{restart_count + 1})")
            
            # Monitor the process
            while self.running and self.process:
                try:
                    # Check if process is still running
                    return_code = self.process.poll()
                    if return_code is not None:
                        print(f"⚠️  Server exited with code {return_code}")
                        break
                    
                    # Read output
                    line = self.process.stdout.readline()
                    if line:
                        line = line.strip()
                        if "You can now view your Streamlit app" in line:
                            print("🌐 Server is ready!")
                        elif "Stopping..." in line:
                            print("🔄 Server stopping...")
                        elif "ERROR" in line or "Exception" in line:
                            print(f"❌ Error: {line}")
                    
                    time.sleep(0.1)
                    
                except Exception as e:
                    print(f"❌ Monitor error: {e}")
                    break
            
            # If we get here, the server stopped
            if self.running:
                restart_count += 1
                print(f"🔄 Restarting server (attempt #{restart_count + 1})...")
                time.sleep(2)
        
        self.cleanup()

def main():
    """Main function"""
    # Change to the correct directory
    script_dir = Path(__file__).parent
    os.chdir(script_dir)
    
    # Check if web_demo.py exists
    if not Path("web_demo.py").exists():
        print("❌ web_demo.py not found in current directory")
        return
    
    # Start the launcher
    launcher = WebDemoLauncher()
    launcher.monitor_server()

if __name__ == "__main__":
    main()