round robin权重轮循算法php实现代码

先上代码，采用PHP脚本语言

rush:PHP;"> /*

• Copyright (C) FatHong
  */

/ 数据初始化，weight: 权重 /
$hosts['a'] = array('weight' => 5,'current_weight' => 0,'count' => 0);
$hosts['b'] = array('weight' => 3,'count' => 0);
$hosts['c'] = array('weight' => 2,'count' => 0);

$result = array();

/ 模拟10次 /
for ($i = 0; $i < 10; $i++) {
round_robin($hosts,$result);
}

/ 输出结果 /
print_r($result);

/ round robin 轮循 /
function round_robin(&$hosts,&$result)
{
$total = 0;
$best = null;

foreach ($hosts as $key => $item) {
$current = &$hosts[$key];
$weight = $current['weight'];

$current['current_weight'] += $weight;
$total += $weight;

if ( ($best == null) || ($hosts[$best]['current_weight'] < 
            $current['current_weight']) ) 
{
  $best = $key;
}

}

$hosts[$best]['current_weight'] -= $total;
$hosts[$best]['count']++;

$result[] = $best;
}

输出结果：

Array ( [0] => a [1] => b [2] => c [3] => a [4] => a [5] => b [6] => a [7] => c [8] => b [9] => a )

负载均衡的服务器中，其实现算法有种是round-robin权重轮循，就是后端的服务器列表中，给每个服务器标上权重，代表它被采用的机率。

这段代码把最简洁的流程剥离出来，没考虑后端挂起等情况，可以知道它是怎么实现的，仅供参考.