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這篇文章主要介紹了round robin權重輪循算法php實現(xiàn)代碼,需要的朋友可以參考下

先上代碼，采用php腳本語言

<?php

/* 

 * Copyright (C) FatHong

 */

/* 數(shù)據(jù)初始化，weight: 權重 */

$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();

/* 模擬10次 */

for ($i = 0; $i < 10; $i++) {

  round_robin($hosts, $result);

}

/* 輸出結果 */

print_r($result);

/* round robin 輪循 */

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;

}

輸出結果：

Array

(

[0] => a

[1] => b

[2] => c

[3] => a

[4] => a

[5] => b

[6] => a

[7] => c

[8] => b

[9] => a

)

負載均衡的服務器中，其實現(xiàn)算法有種是round-robin權重輪循，就是后端的服務器列表中，給每個服務器標上權重，代表它被采用的機率。

這段代碼把最簡潔的流程剝離出來，沒考慮后端掛起等情況，可以知道它是怎么實現(xiàn)的，僅供參考.