Сокеты. Не пойму некоторые участки кода

<?php
$socket = stream_socket_server("tcp://localhost:900", $errno, $errstr);
 
$connects = array();
 
while (true) {
    $read = $connects;
    $read[] = $socket;
    $write = $except = null;
 
    if (!stream_select($read, $write, $except, null)) {
        continue;
    }
 
    if (in_array($socket, $read)) {
        if (($connect = stream_socket_accept($socket, -1)) && $info = handshake($connect)) {
            $connects[] = $connect;
        }
 
        unset($read[ array_search($socket, $read) ]);
    }
 
    foreach($read as $connect) {
        $data = fread($connect, 100000);
 
        if (strlen($data) == 0) {
            fclose($connect);
            unset($connects[ array_search($connect, $connects) ]);
 
            continue;
        }
        
        sendMessage($connect, decode($data)["payload"]);
    }
}
 
fclose($socket);
?>

function sendMessage($cs, $data) {
    foreach($cs as $connect) {
        fwrite($connect, encode($data));
    }
}