How can I run a blPop in a continuous loop?

[mikegioia]

I've got the blocking list pop example working from the repo, however, I'm unable to get the blpop working in a continuous loop.

$connection = "tcp://localhost:6379";
$consumer = new \Predis\Async\Client( $connection )
$consumer->connect(
    function ( $consumer ) {
        echo "Connected to Redis, blpop'ing on queue:*\n";
        $consumer->blpop(
            'queue:normal',
            0,
            function ( $response ) use ( $consumer ) {
                list( $priority, $job ) = $response;

                if ( $priority ):
                    $message = "`%s` from channel `%s`.\n";
                    $feedback = sprintf( $message, $job, $priority );
                    echo $feedback;
                endif;

                return TRUE;
            });
    });
$consumer->getEventLoop()->run();

When I run this code with items in the queue, it will process the first one but then halt and hang in the terminal. Is there a way to have this blpop continuously block and then pop an item when it finds one?

[padakuro]

As far as I know there's no built in way for this (correct me if I'm wrong), so just put the ->blpop() call inside another method/function and call itself inside the blpop callback.

function process($consumer) {
  $consumer->blpop(
            'queue:normal',
            0,
            function ( $response ) use ( $consumer ) {
                list( $priority, $job ) = $response;

                if ( $priority ):
                    $message = "`%s` from channel `%s`.\n";
                    $feedback = sprintf( $message, $job, $priority );
                    echo $feedback;
                endif;

                process($consumer);
            });
}

$connection = "tcp://localhost:6379";
$consumer = new \Predis\Async\Client( $connection )

$consumer->connect(
    function ( $consumer ) {
       echo "Connected to Redis, blpop'ing on queue:*\n";
       process($consumer);
    }
);

[nrk]

Hi @mikegioia,

like pointed out by @padakuro you need to manually reschedule the BLPOP operation because, unlike commands such as SUBSCRIBE for channels, it blocks only until there's one item available in the list.

[mikegioia]

Ah, thanks to both of you!