随机重定向均匀php

Question

I have a simple php code that redirect to random uri from array. However, after a while i've noticed its not evenly load balanced. Can someone suggest tweaking so it will be evenly redirecting between the links ?

<?php 
$urls = array('https://a.com', 
               'http://b.com', 
               'http://c.com', 
               'http://d.com',
               'https://e.com',
               'https://f.com'
               ); 
shuffle($urls);
header('Location: ' . $urls[0]);
exit();
?>

Thanks

Answer 1

Evenly and randomly are contradictory. But you can use a stack instead of an array to limit the randomness. Drawback is that you then need storage between script calls. For example :

<?php
$urls=readStack();
if(empty($urls)) {
         $urls = shuffle(array('https://a.com', 
                'http://b.com', 
                'http://c.com', 
                'http://d.com',
                'https://e.com',
                'https://f.com'
               )); 
$url=array_pop($urls);
storeStack($urls);
header('Location: ' . $url);

Where storeStack() and readStack() functions are intended to store and retrieve your stack status from persistent storage. This could be done via file system storage, database access, or a memcache mechanism,... whatever is at your disposal and fast enough for your app. Here is a basic example with file system and serialize :

<?php
define( 'STOREFILENAME', '/tmp/urlstack');

function storeStack($value){
     file_put_contents(STOREFILENAME, serialize( $value ));
}

function readStack($varname){
     return unserialize(file_get_contents(STOREFILENAME));
}