PHP一致性hash分布式算法封装类定义与用法示例


            本文实例讲述了PHP一致性hash分布式算法封装类定义与用法。分享给大家供大家参考，具体如下：

一、无虚拟节点实现





<?php

/**

 * 一致性hash分布式算法

 * @param $key

 * @return int

 * 实现步骤

 * 1.先将0~ 是32位最大带符号整数（0x7FFFFFFF） 想象成一个闭环

 * 2.将服务器列表通过hash算法分布在 圆环之中

 * 3.将key值也分布在圆环之中

 * 4.通过_isSorted判断服务器是否需要进行倒序排序 排序后遍历服务器 找到最近的服务器 返回

 * hash算法是不保证平衡的 为了尽量保证平衡性 我们应该加入虚拟节点数 将一个服务器节点虚拟化成为多个 较大程度上保证了平衡性

 */

class FlexiHash{

  private $_serverList = array();

  private $_isSorted = false;

  private $_virtual_node_num = 20;//虚拟节点数 服务器越少 增加的虚拟节点数应该越多

  //通过hash算法返回一个整数值

  protected function myHash($key){

    $md5 = substr(md5($key),0,8);

    $seed = 31; //种子值

    $hash=0;

    for($i=0;$i<8;$i++){

      $hash = $hash*$seed+ord($md5{$i}); //ord 返回ascii值

      $i++;

    }

    return $hash&0x7FFFFFFF; //0x7FFFFFFF表示最大值

  }

  //添加服务器

  function addServer($server){

    $hash =$this->myHash($server. '#1');

    if(!isset($this->_serverList[$hash])) {

      for ($i = 1; $i <= $this->_virtual_node_num; $i++) {

        $hash = $this->myHash($server . '#' . $i);

        $this->_serverList[$hash] = $server;

      }

    }

    $this->_isSorted = false;

    return true;

  }

  //删除服务器

  function removeServer($server){

    for ($i = 1; $i <= $this->_virtual_node_num; $i++) {

      $hash = $this->myHash($server . '#' . $i);

      unset($this->_serverList[$hash]);

    }

    $this->_isSorted = false;

    return true;

  }

  //获取服务器

  function lookup($key){

    $hash =$this->myHash($key);

    if(!$this->_isSorted){

      krsort($this->_serverList,SORT_NUMERIC);

      $this->_isSorted = true;

    }

    foreach($this->_serverList as $pos=>$server){

      if($hash >= $pos) return $server;

    }

    return end($this->_serverList);

  }

  public function getServerList(){

    krsort($this->_serverList,SORT_NUMERIC);

    return $this->_serverList;

  }

}

//demo test

$hserver = new FlexiHash();

//添加服务器

$hserver->addServer('192.168.1.1');

$hserver->addServer('192.168.1.2');

$hserver->addServer('192.168.1.3');

$hserver->addServer('192.168.1.4');

$hserver->addServer('192.168.1.5');

$key1='Key1111';

$key2='Key2222';

$key2='Key3333';

$key2='Key4444';

$key2='Key5555';

$key2='Key6666';

echo "save key1 in server: ".$hserver->lookup($key1).PHP_EOL;

echo "save key2 in server: ".$hserver->lookup($key2).PHP_EOL;

echo "save key1 in server: ".$hserver->lookup($key3).PHP_EOL;

echo "save key2 in server: ".$hserver->lookup($key4).PHP_EOL;

echo "save key1 in server: ".$hserver->lookup($key5).PHP_EOL;

echo "save key2 in server: ".$hserver->lookup($key6).PHP_EOL;

echo "================================================".PHP_EOL;

//移除服务器 key值将自动转义到下一台服务器

$hserver->removeServer('192.168.1.4');

echo "save key1 in server: ".$hserver->lookup($key1).PHP_EOL;

echo "save key2 in server: ".$hserver->lookup($key2).PHP_EOL;

echo "save key1 in server: ".$hserver->lookup($key3).PHP_EOL;

echo "save key2 in server: ".$hserver->lookup($key4).PHP_EOL;

echo "save key1 in server: ".$hserver->lookup($key5).PHP_EOL;

echo "save key2 in server: ".$hserver->lookup($key6).PHP_EOL;

echo "================================================".PHP_EOL;

//恢复故障服务器 key值将恢复原来服务器

$hserver->addServer('192.168.1.4');

echo "save key1 in server: ".$hserver->lookup($key1).PHP_EOL;

echo "save key2 in server: ".$hserver->lookup($key2).PHP_EOL;

echo "save key1 in server: ".$hserver->lookup($key3).PHP_EOL;

echo "save key2 in server: ".$hserver->lookup($key4).PHP_EOL;

echo "save key1 in server: ".$hserver->lookup($key5).PHP_EOL;

echo "save key2 in server: ".$hserver->lookup($key6).PHP_EOL;







二、运行结果：



save key1 in server: 192.168.1.4

save key2 in server: 192.168.1.4

save key1 in server: 192.168.1.3

save key2 in server: 192.168.1.3

save key1 in server: 192.168.1.3

save key2 in server: 192.168.1.3

================================================

save key1 in server: 192.168.1.2

save key2 in server: 192.168.1.5

save key1 in server: 192.168.1.3

save key2 in server: 192.168.1.3

save key1 in server: 192.168.1.3

save key2 in server: 192.168.1.3

================================================

save key1 in server: 192.168.1.4

save key2 in server: 192.168.1.4

save key1 in server: 192.168.1.3

save key2 in server: 192.168.1.3

save key1 in server: 192.168.1.3

save key2 in server: 192.168.1.3



PS：这里再为大家提供2款hash相关在线工具供大家参考使用：

在线散列/哈希算法加密工具：

http://tools.zwyuanma.com/password/hash_encrypt

在线MD5/hash/SHA-1/SHA-2/SHA-256/SHA-512/SHA-3/RIPEMD-160加密工具：

http://tools.zwyuanma.com/password/hash_md5_sha

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希望本文所述对大家PHP程序设计有所帮助。