Threading wait POC 4

threading_wait4.py

import threading
import time
import signal

class ControlledExecution:
    def __init__(self):
        self.lock = threading.Lock()
        self.condition = threading.Condition(self.lock)
        self.shutdown = False

    def worker(self):
        print("Worker started. Press Ctrl+C to stop.")
        for i in range(10):  # Simulated task
            with self.lock:
                if self.shutdown:
                    print("Worker stopping early.")
                    return  # Ensure clean exit
            print(f"Processing item {i}...")
            time.sleep(2)  # Simulate time-consuming task
        print("Worker finished processing all items.")

    def main_loop(self):
        # Set initial signal handler for Ctrl+C
        signal.signal(signal.SIGINT, self.handle_ctrl_c)
        
        thread = threading.Thread(target=self.worker)
        thread.start()

        try:
            while not self.shutdown:
                time.sleep(1)  # Wait for shutdown signal with minimal CPU usage
        except KeyboardInterrupt:
            pass  # Just in case, but handle_ctrl_c should catch the first Ctrl+C

        thread.join()

    def signal_shutdown(self):
        with self.lock:
            self.shutdown = True
        with self.condition:
            self.condition.notify_all()  # Wake up waiting threads

    def handle_ctrl_c(self, signum, frame):
        print("Shutdown signal received, shutting down gracefully...")
        self.signal_shutdown()
        # Ignore further SIGINT signals after the first one
        signal.signal(signal.SIGINT, signal.SIG_IGN)

if __name__ == "__main__":
    controlled_execution = ControlledExecution()
    controlled_execution.main_loop()
    print("Main program exited gracefully.")