Fatal error: Uncaught AssertionError: assert($fiber !== $this->fiber) when server::stop() in Windows sapi_windows_set_ctrl_handler()

[DrLightman]

I adapted the last lines of the example in the README to Windows, because SIGINT (pcntl) is not available there.
I converted it this way making use of sapi_windows_set_ctrl_handler($callback) to intercept CTRL+C whilst the script is running in a terminal.

EventLoop::defer( function () use ( $logger, $server ): void {
    $logger->info( 'OS: Windows' );
    // async wait for server admin to hit CTRL+C
    sapi_windows_set_ctrl_handler( function ( int $event ) use ( $logger, $server ) {
        $logger->info( sprintf( "Received signal, stopping HTTP server" ) );
        $server->stop();
    } );
} );

EventLoop::run();

The callback is fired, the server says is stopping, but an assertion fires afterward, I don't think it successfully stops:

...
...
[2025-01-05T14:39:38.870938+00:00] server.info: OS: Windows
[2025-01-05T14:39:41.882420+00:00] server.info: Received signal, stopping HTTP server
[2025-01-05T14:39:41.882738+00:00] server.info: Stopping server

Fatal error: Uncaught AssertionError: assert($fiber !== $this->fiber) in D:\server-php\vendor\revolt\event-loop\src\EventLoop\Internal\AbstractDriver.php:293
Stack trace:
#0 D:\server-php\vendor\revolt\event-loop\src\EventLoop\Internal\AbstractDriver.php(293): assert(false, 'assert($fiber !...')
#1 D:\server-php\vendor\revolt\event-loop\src\EventLoop.php(392): Revolt\EventLoop\Internal\AbstractDriver->getSuspension()
#2 D:\server-php\vendor\amphp\amp\src\Internal\FutureIterator.php(130): Revolt\EventLoop::getSuspension()
#3 D:\server-php\vendor\amphp\amp\src\Future.php(59): Amp\Internal\FutureIterator->consume()
#4 D:\server-php\vendor\amphp\amp\src\Future\functions.php(118): Amp\Future::iterate(Array, NULL)
#5 D:\server-php\vendor\amphp\http-server\src\SocketHttpServer.php(402): Amp\Future\awaitAll(Array)
#6 D:\server-php\start-php8.php(88): Amp\Http\Server\SocketHttpServer->stop()
#7 [internal function]: {closure:D:\server-php\start-php8.php:85}(0)
#8 D:\server-php\vendor\revolt\event-loop\src\EventLoop\Driver\StreamSelectDriver.php(254): stream_select(Array, Array, Array, 0, 999642)
#9 D:\server-php\vendor\revolt\event-loop\src\EventLoop\Driver\StreamSelectDriver.php(133): Revolt\EventLoop\Driver\StreamSelectDriver->selectStreams(Array, Array, 0.9996424000019)
#10 D:\server-php\vendor\revolt\event-loop\src\EventLoop\Internal\AbstractDriver.php(489): Revolt\EventLoop\Driver\StreamSelectDriver->dispatch(true)
#11 D:\server-php\vendor\revolt\event-loop\src\EventLoop\Internal\AbstractDriver.php(552): Revolt\EventLoop\Internal\AbstractDriver->tick(true)
#12 [internal function]: Revolt\EventLoop\Internal\AbstractDriver->{closure:Revolt\EventLoop\Internal\AbstractDriver::createLoopFiber():533}()
#13 D:\server-php\vendor\revolt\event-loop\src\EventLoop\Internal\AbstractDriver.php(113): Fiber->resume()
#14 D:\server-php\vendor\revolt\event-loop\src\EventLoop.php(406): Revolt\EventLoop\Internal\AbstractDriver->run()
#15 D:\server-php\start-php8.php(106): Revolt\EventLoop::run()
#16 {main}
  thrown in D:\server-php\vendor\revolt\event-loop\src\EventLoop\Internal\AbstractDriver.php on line 293

This is not breaking the script atm but maybe it's worth taking a look into it?

[bwoebi]

The problem is that sapi_windows_set_ctrl_handler works via the internal interrupt mechanism and will cause execution of its closure within the event loop fiber itself (where fiber switches are not allowed).

I haven't tested it, but wrapping the contents of the closure inside EventLoop::queue (microtask) may work, i.e.:

    sapi_windows_set_ctrl_handler( function ( int $event ) use ( $logger, $server ) {
        EventLoop::queue(function() use ($looger, $server) {
            $logger->info( sprintf( "Received signal, stopping HTTP server" ) );
            $server->stop();
        });
    } );

[bwoebi]

But absent manual handling to defer, it would probably require support in Revolt itself, as part of the event loop.

[DrLightman]

Thank you for the ideas, I tried I think almost all combinations of closures/scopes but the error persists, maybe it hasn't solution with the actual state of the library, maybe I'll drop an issue in the github of Revolt.