Linux signal信号处理机制与信号掩码

#!/bin/env python3
import os
import time
import fcntl
import signal
import argparse


SIGNAL = signal.SIGUSR1

SIGNAL_BLOCKING = False


# Define signal block
def signal_block(func):

    def _inner(*args, **kwargs):
        if not SIGNAL_BLOCKING:
            print(f"Non signal blocking function handling")
            return func(*args, **kwargs)

        # Block SIGUSR1 while handling the signal
        print(f"Signal blocking function handling")
        old_mask = signal.pthread_sigmask(signal.SIG_BLOCK, {SIGNAL})
        try:
            func(*args, **kwargs)
        finally:
            # Restore the old signal mask
            signal.pthread_sigmask(signal.SIG_SETMASK, old_mask)
    return _inner


# Define the signal handler
@signal_block
def signal_handler(signum, frame):
    print(f"Signal {signum} received.")
    lock_file_hello()


# Set up the signal handling
def setup_signal_handling():
    signal.signal(SIGNAL, signal_handler)


def lock_file_hello(file_path='hello.lock'):
    with open(file_path, 'a') as file:
        try:
            # Acquire an exclusive lock
            fcntl.flock(file, fcntl.LOCK_EX)
            print(f"Locked {file_path} ")

            print(f"Work start ")

            # Simulate work
            time.sleep(10)

            print(f"Work done")

        finally:
            # Release the lock
            fcntl.flock(file, fcntl.LOCK_UN)
            print(f"Unlocked {file_path}")


# Parse signal blocking option
def parse_option():
    global SIGNAL_BLOCKING

    parser = argparse.ArgumentParser(description="Example script with blocks of options")

    parser.add_argument('--block', action='store_true', help='Enable signal blocking')

    args = parser.parse_args()

    SIGNAL_BLOCKING = args.block


# Main function to run the program
def main():
    parse_option()
    setup_signal_handling()
    print(f"Waiting for a signal, sending using 'kill -s {SIGNAL} {os.getpid()}'")
    while True:
        time.sleep(10)


if __name__ == "__main__":
    main()