PHP如何?round robin權重輪循演算法

PHP如何?round robin權重輪循演算法？本文主要介紹了round robin權重輪循演算法php實現代碼，需要的朋友可以參考下。希望對大家有所協助。

先上代碼，採用php指令碼語言

<?php/*  * Copyright (C) FatHong *//* 資料初始化，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();/* 類比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
)

負載平衡的伺服器中，其實現演算法有種是round-robin權重輪循，就是後端的伺服器列表中，給每個伺服器標上權重，代表它被採用的機率。

這段代碼把最簡潔的流程剝離出來，沒考慮後端掛起等情況，可以知道它是怎麼實現的，僅供參考.

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