权重轮询调度算法

直接上代码了

<?php
class WeightedRoundRobin
      {
        private static $_weightArray = array();
         
        private static $_i = -1;//代表上一次选择的服务器
        private static $_gcd;//表示集合S中所有服务器权值的最大公约数
        private static $_cw = 0;//当前调度的权值
        private static $_max;
        private static $_n;//agent个数
         
        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];
                }
            }
        }
 
      }
      ?>

客户端代码：

<?php
include('WeightedRoundRobin.php');
$arr = array(
                array('id' => 'A', 'weight' => 3),
                array('id' => 'B', 'weight' => 3),
                array('id' => 'C', 'weight' => 3),
                array('id' => 'D', 'weight' => 3),
                array('id' => 'E', 'weight' => 3),
                
        );
        $weight = new WeightedRoundRobin($arr);
        
        $a=0;
        $b=0;
        $c=0;
        $d=0;
        $e=0;
        for ($j = 0; $j < 1; $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;

测试结果: