round robin权重轮循算法php实现代码

先上代码，采用php脚本语言<?php/**Copyright(C)FatHong*//*数据初始化，weight:权重*/$hosts['a']=a

先上代码，采用php脚本语言

<?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, 'current_weight' => 0, 'count' => 0);
$hosts['c'] = array('weight' => 2, 'current_weight' => 0, '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.

round robin 权重轮循