php address 127 port 81 set_time_limit error_reporting E_ALL sock sock

<?php

$address = '127.0.0.1';
$port = 81;

set_time_limit (0);
error_reporting(E_ALL);

$sock = socket_create(AF_INET, SOCK_STREAM, 0);
socket_bind($sock, $address, $port);
socket_listen($sock);

$client = null;
while (!$client)
{
    if ($newsock = @socket_accept($sock))
    {
        if (is_resource($newsock))
        {
            echo "New client connected \n";
            $client = $newsock;
        }
    }
    sleep(1);
}

$cache = new LimitedCache();

while(true){
    if(!@socket_write($client, ">"))
        break;
    $str = socket_read($client, 1024);

    $data = explode(' ', $str);
    if(count($data) == 1)
        @socket_write($client, $cache->get(trim($data[0])));
    else
        @socket_write($client, $cache->set(trim($data[0]), $data[1]));
    @socket_write($client, "\n");
}

class Node
{
    public $data;
    public $prev;
    public $next;

    function __construct($data)
    {
        $this->data = $data;
        $this->prev = null;
        $this->next = null;
    }
}

class LimitedCache{
    public $head = null;
    public $tail = null;
    public $map = array();
    public $count = 0;

    public $limit = 3;

    public function set($key, $val){
        $is_exist = array_key_exists($key, $this->map);
        $deleted_key = null;

        if(!$is_exist){
            list($deleted_key, $link) = $this->_insert($key);
            if($deleted_key)
                unset($this->map[$deleted_key]);
        }
        else
            $this->_update($this->map[$key]['link']);

        $this->map[$key] = array('data' => $val, 'link' => $link);
        return ($is_exist ? 'Updated': 'Saved').
            ($deleted_key ? ', deleting '.$deleted_key : "");
    }

    function get($key){
        return array_key_exists($key, $this->map)
            ? $this->map[$key]['data'] : 'Not found';
    }

    public function _insert($data){
        $link = new Node($data);
        $link->prev = $this->tail;

        if(!$this->tail)
            $this->head = $this->tail = &$link;
        else{
            $this->tail->next = &$link;
            $this->tail = &$link;
        }

        $deleted_key = null;

        $this->count += 1;
        if($this->count > $this->limit){
            // remove head as it's the oldest
            $deleted_key = $this->head->data;

            $old_head = $this->head;
            $this->head = $this->head->next;
            $this->head->prev = null;
            unset($old_head);
            $this->count -= 1;
        }

        echo "Inserting ".$data."\n";
        if($deleted_key)
            echo "Deleting ".$deleted_key."\n";
        return array($deleted_key, &$link);
    }

    public function _update($link){
        echo "Updating ".$link->data."\n";
        if($link == $this->tail)
            return;
        // remove link from whatever it was
        if($link->prev)
            $link->prev->next = $link->next;
        if($link->next)
            $link->next->prev = $link->prev;
            $this->tail = $link->prev;
        if($link == $this->head)
            $this->head = $link->next;

        // now move it to the tail
        $this->tail->next = $link;
        $link->prev = $this->tail;
        $link->next = null;
        $this->tail = $link;
    }
}