Getting a response as NULL after 4 minutes

[marioshtika]

I am sending multiple requests to one or more TCP client, using the below code

$promises = [];
foreach ($packets as $packet) {
    $promises[] = call(function () use ($packet, $uri) {

        /** @var \Amp\Socket\ClientSocket $socket */
        $socket = yield connect($uri);
        try {
            yield $socket->write($packet);

            $chunk = yield $socket->read(); // modbus packet is so small that one read is enough
            if ($chunk === null) {
                return null;
            }
            return ResponseFactory::parseResponse($chunk);
        } finally {
            $socket->close();
        }
    });
}

try {
    // will run multiple request in parallel using non-blocking php stream io
    $responses = wait(all($promises));
    // print_r($responses);
} catch (Throwable $e) {
    print_r($e);
}

One of the clients is delaying too much and after approximately 4 minutes it returns "null".

Can you help me understand what happens after 4 minutes?
Is this something like a timeout for the read command?
Can I change it for example to 1 minute?

Thank you in advance

[kelunik]

My guess is that the other side closes the connection after that time.

[marioshtika]

Thank you @kelunik for the quick response.

Is there a function to add a timeout for the read() command?

Thank you in advance?

[kelunik]

We currently don't have cancelation support for reads, but you can use Amp\Promise\timeout to apply a timeout to any promise. However, this will not cancel the operation, but closing the socket on timeout will.

[marioshtika]

Thank you @kelunik for your suggestion.

Do you think it's ok to put that timeout() before the read() function, since read() also returns a promise, instead of putting it in the wait() function?

Example:

$chunk = yield timeout($socket->read(), 1000);

[kelunik]

Yup, that's generally how you do it.