change signal to SIG_DFL after exit_gracefully

[zrr1999]

Description

I want to create multiple windows in my program, so I ran multiple app_async functions. However, I found that when I ran multiple app_async functions, Ctrl+C could not terminate my program.

Modifying exit_gracefully to ensure that the default value of the signal is restored after execution seems to be a solution.

Test Code

import asyncio
import flet as ft
import socket


def get_free_port():
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.bind(("", 0))
    _, port = s.getsockname()
    s.close()
    return port


def main(page):
    page.snack_bar = ft.SnackBar(
        content=ft.Text("Hello, world!"),
        action="Alright!",
    )

    page.add(ft.ElevatedButton("Open SnackBar"))


loop = asyncio.new_event_loop()


async def hello_world():
    loop.create_task(ft.app_async(target=main, port=get_free_port()))
    while True:
        await asyncio.sleep(1)


loop.create_task(hello_world())
loop.run_until_complete(hello_world())

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• I signed the CLA.
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings

• New and existing tests pass locally with my changes
• I have made corresponding changes to the documentation (if applicable)

Screenshots (if applicable):

Additional details

Summary by Sourcery

This pull request addresses an issue where the program could not be terminated using Ctrl+C when running multiple app_async functions. The fix involves restoring the default signal handlers for SIGINT and SIGTERM after the exit_gracefully function is executed.

• Bug Fixes:
  • Restored default signal handlers for SIGINT and SIGTERM after executing the exit_gracefully function to ensure proper termination of the program when running multiple app_async functions.

[sourcery-ai]

Reviewer's Guide by Sourcery

This pull request addresses an issue where multiple instances of the app_async function prevent the program from terminating with Ctrl+C. The solution involves modifying the exit_gracefully function to restore the default signal handlers for SIGINT and SIGTERM after execution.

File-Level Changes

Files	Changes
sdk/python/packages/flet-runtime/src/flet_runtime/app.py	Modified the exit_gracefully function to reset signal handlers for SIGINT and SIGTERM to their default values after execution to ensure proper termination of the program when multiple app_async functions are running.

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[sourcery-ai]

Hey @zrr1999 - I've reviewed your changes and they look great!

Here's what I looked at during the review

• 🟡 General issues: 1 issue found
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟢 Complexity: all looks good
• 🟢 Documentation: all looks good

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[sourcery-ai]

issue (bug_risk): Potential race condition with signal handling.

Reverting the signal handlers to their default behavior within exit_gracefully might introduce a race condition if another signal is received before the program exits. Consider ensuring that the program exits immediately after setting the default handlers.