分享一个权重随机算法

<?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 init()
        {

        }

        public function initParam(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]['id'];
                }
            }
        }
    }

本作品采用《CC 协议》，转载必须注明作者和本文链接