Hanging connector

[DangerLifter]

require_once __DIR__.'/vendor/autoload.php';

$inner = count($argv) > 1;

$loop = new \React\EventLoop\ExtEventLoop();

$connector = new React\Socket\Connector($loop);

runme($loop, $connector, $inner);

if (!$inner) {
    echo "Outer start\n";
    $loop->run();
}

function runme(\React\EventLoop\LoopInterface $loop, React\Socket\Connector $connector, $inner)
{
    $connector->connect('tcp://127.0.0.1:3306')->
    then(function (\React\Socket\ConnectionInterface $conn) {
        echo ("Hello MySQL!\n");
        $conn->close();
    },function ($e) {
        echo ("Bye MySQL!\n");
    })->done();

    if ($inner) {
        echo "Inner start\n";
        $loop->run();
    }

    echo "Exit runme\n";
}

it works proper and returns:

$ php ./testMysql.php 
Exit runme
Outer start
Hello MySQL!
$ php ./testMysql.php  --inner
Inner start
Hello MySQL!
Exit runme

But if you go into \React\Socket\TcpConnector::waitForStreamOnce() and remove $canceller function in new Promise object like below, than it hangs again. Looks like it works in latest version of react a kind of accidentally as socket not stored obvious way, and in fact similar to code in v0.4.6.

private function waitForStreamOnce($stream)
    {
        $loop = $this->loop;

        return new Promise\Promise(function ($resolve, $reject) use ($loop, $stream) {
            $loop->addWriteStream($stream, function ($stream) use ($loop, $resolve, $reject) {
                $loop->removeWriteStream($stream);

                // The following hack looks like the only way to
                // detect connection refused errors with PHP's stream sockets.
                if (false === stream_socket_get_name($stream, true)) {
                    fclose($stream);

                    $reject(new \RuntimeException('Connection refused'));
                } else {
                    $resolve(new Connection($stream, $loop));
                }
            });
        });
    }

$ php ./testMysql.php  --inner
Inner start
.....HANGING
$ php ./testMysql.php 
Exit runme
Outer start
...HANGING

Initial discussion here: https://stackoverflow.com/questions/47551054/php-7-1-pecl-event-libevent-is-hanging-in-weird-case

[clue]

it works proper and returns:
[…]
But if you go into \React\Socket\TcpConnector::waitForStreamOnce() and remove $canceller function in new Promise object like below, than it hangs again. Looks like it works in latest version of react a kind of accidentally as socket not stored obvious way, and in fact similar to code in v0.4.6.

Thanks for reporting, but I'm not sure I follow the problem you're seeing? The first gist seems to work just fine and this only breaks when you manipulate this library? Note that v0.4.6 is somewhat outdated and we have significantly improved our code base and test suite since then.

Can the problem be reproduced with the latest version?

[DangerLifter]

You are correct that problem appears only in case of library's manipulation. But as I understand problem happens because reference to stream/socket is not saved properly and for current version it works accidentally, just because reference is used in cancellation callback. So if I am right, I guess it points to conceptual problem/mistake in architecture that should be solved obvious way.

[clue]

Thank you for raising this discussion and confirming this behavior! It looks like we may we have found an issue in the underlying EventLoop component thanks to your report and @rosmanov's excellent answer to your SO question.

I've filed a WIP-PR to highlight this issue in the EventLoop component: reactphp/event-loop#123. I don't think there's much that needs to be done here in this component, so I think it makes sense to keep track of the progress there instead.

Thank you!