php权重分配

 1 class WeightService 2 {
 3     protected $container;
 4     protected $weight = 0;
 5 
 6     public function __construct($arr)
 7     {
 8         if (!count($arr)){
 9             $this->container = [];
10         }else {
11             foreach ($arr as $item) {
12                 $weight = $item[‘weight‘] * 10000;//扩大权重 提高单次的精确度 我感觉是有用的=。= 觉得没用的 可以拿掉 哈哈哈~
13                 $this->weight += $weight;
14                 $array[‘id‘] = $item[‘id‘];
15                 $array[‘weight‘] = $weight;
16                 $container[] = $array;
17             }
18             $this->container = $container;
19         }
20     }
21 
22     public function getUid()
23     {
24         $random = $this->random();
25         //初始化区间参数
26         $left = 0;//左闭区间
27         $right = 0;//右开区间
28         foreach ($this->container as $item){
29             //区间宽度
30             $size = $item[‘weight‘];
31             //右区间 + 区间宽度
32             $right += $size;
33             if ($random >= $left && $random < $right) {
34                 return $item[‘id‘];
35             }else{
36                 //准备下一轮的循环 左区间 + 区间宽度
37                 $left += $size;
38             }
39         }
40         return 0;
41     }
42 
43     protected function random()
44     {
45         //右边是开区间  这个生成的是闭区间 所以要 -1
46         return mt_rand(0, $this->weight - 1);
47     }
48 }