Ability to select on an additional socket

[thekid]

...like in https://github.com/xp-forge/websockets:

use io\redis\RedisProtocol;
use websocket\{Listener, Listeners};

class Example extends Listeners {

  public function serve($listeners) {
    $dsn= ...;
    $queue= ...;

    // Subscribe to the Redis queue and handle 
    $protocol= new RedisProtocol($dsn);
    $protocol->command('SUBSCRIBE', $queue);
    $listeners->add($protocol->socket(), function($protocol) {
      $message= $protocol->receive();
      // ...shortened for brevity...
    });
  }

  return function($conn, $payload) { /* ... */ };
}

This would make it possible to broadcast messages as seen here: https://github.com/thekid/crews/blob/main/src/main/php/de/thekid/crews/Feed.php

[thekid]

Inside web.Application, this could be accomplished as follows:

use web\Application;

class Ws extends Application {

  public function routes() {

    // -- Here ---------------------------------------------
    $protocol= new RedisProtocol($dsn);
    $protocol->command('SUBSCRIBE', $queue);
    $this->select($protocol->socket(), function($protocol) {
      $message= $protocol->receive();
      // ...shortened for brevity...
    });
    // -----------------------------------------------------

    return [
      '/ws' => new WebSocket(function($conn, $payload) { /* ... */ }),
      '/'   => function($request, $response) {
         // ...shortened for brevity...
      }
    ];
  }
}

[thekid]

See #130