Mixup PHP curl routines with memcache

ServeMixup.php

<?php
// Copyright Stephen Perelson
//
// Example PHP script to get a banner from http://mixup.hapnic.com
// Adds a 1 minute cache of the banner using Memcache
// Untested code
//
// Mixup is a cross-Promotion Linksharing service for Mxit web apps 

class ServeMixup {
    // Call get_link to return a string with a new link
    public function get_link($Mxit_Referral_ID) {
        $url = "http://serve.mixup.hapnic.com/" . $Mxit_Referral_ID;
        $memcache = $this->get_memcache();
        
        if ($memcache === false) {
            $link = $this->curl_get_link($url);
        } else {
            $key = "YOUR_MEMCACHE_KEY_mixup_banner";
            $ttl = 60; // 1 minute
            
            if ($memlink = $memcache->get($key)) {
                $link = $memlink;
            } else {
                $link = $this->curl_get_link($url);     
                $memcache->replace($key, $link, false, $ttl) || $memcache->set($key, $link, false, $ttl);
            }
        }
        return $link;
    }

    private function curl_get_link($url) {
        $curl = curl_init();
        curl_setopt($curl, CURLOPT_URL, $url);
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($curl, CURLOPT_CONNECTTIMEOUT, 2);
        curl_setopt($curl, CURLOPT_TIMEOUT, 3);
        $link = curl_exec($curl);
        $httpcode = curl_getinfo($curl, CURLINFO_HTTP_CODE);
        $errno = curl_errno($curl);
        curl_close($curl);
    
        if ($errno == 0 && $httpcode == 200 && strlen($link) > 0) { // No curl errors
            return $link;
        }
        return '';
    }
    
    private function get_memcache() {
        $usemem = false;

        if (extension_loaded('memcache')) {
            $usemem = true;
        }
        if ($usemem) {
            $memcache_server = 'Your_memcacheserver';
            $memcache_port = '11211';
            
            $memcache = new Memcache;           
            $memcache->addServer($memcache_server, $memcache_port);
                
            return $memcache;
        }
        return false;
    }
}