php 權重輪詢調度算法代碼
<?php
class WeightedRoundRobin
{
private static $_weightArray = array();
private static $_i = -1;//代表上一次選擇的服務器
private static $_gcd;//表示集合S中所有服務器權值的最大公約數
private static $_cw = 0;//當前調度的權值
private static $_max;
private static $_n;//agent個數
public function __construct(array $weightArray)
{
self::$_weightArray = $weightArray;
self::$_gcd = self::getGcd(self::$_weightArray);
self::$_max = self::getMaxWeight(self::$_weightArray);
self::$_n = count($weightArray);
}
private static function getGcd(array $weightArray)
{
$temp = array_shift($weightArray);
$min = $temp['weight'];
$status = false;
foreach ($weightArray as $val) {
$min = min($val['weight'],$min);
}
if($min == 1){
return 1;
}else{
for ($i = $min; $i>1; $i--) {
foreach ($weightArray as $val) {
if (is_int($val['weight']/$i)) {
$status = true;
}else{
$status = false;
break;
}
}
if ($status) {
return $i;
}else {
return 1;
}
}
}
}
private static function getMaxWeight(array $weightArray)
{
if(empty($weightArray)){
return false;
}
$temp = array_shift($weightArray);
$max = $temp['weight'];
foreach ($weightArray as $val) {
$max = max($val['weight'],$max);
}
return $max;
}
public function getWeight()
{
while (true){
self::$_i = ((int)self::$_i+1) % (int)self::$_n;
if (self::$_i == 0) {
self::$_cw = (int)self::$_cw - (int)self::$_gcd;
if (self::$_cw <= 0) {
self::$_cw = (int)self::$_max;
if (self::$_cw == 0) {
return null;
}
}
}
if ((int)(self::$_weightArray[self::$_i]['weight']) >= self::$_cw) {
return self::$_weightArray[self::$_i];
}
}
}
}
?>
客戶端代碼：在thinkphp中實現
<?php
class IndexAction extends Action {
public function index(){
import("COM.WeightedRoundRobin");
$arr = array(
array('id' => 'A', 'weight' => 3),
array('id' => 'B', 'weight' => 3),
array('id' => 'C', 'weight' => 6),
array('id' => 'D', 'weight' => 4),
array('id' => 'E', 'weight' => 1),
);
$weight = new WeightedRoundRobin($arr);
$a=0;
$b=0;
$c=0;
$d=0;
$e=0;
for ($j = 0; $j < 100; $j++) {
$weightInfo = $weight->getWeight();
echo $weightInfo['id'].'----------------------weight:'.$weightInfo['weight'].'<br/>';
if($weightInfo['id'] == 'A'){
$a++;
}
if($weightInfo['id'] == 'B'){
$b++;
}
if($weightInfo['id'] == 'C'){
$c++;
}
if($weightInfo['id'] == 'D'){
$d++;
}
if($weightInfo['id'] == 'E'){
$e++;
}
}
echo 'A:'.$a.'<br/>';
echo 'B:'.$b.'<br/>';
echo 'C:'.$c.'<br/>';
echo 'D:'.$d.'<br/>';
echo 'E:'.$e.'<br/>';
exit;
$this->display();
}
}
*
