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：

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

　　更多关于PHP相关内容感兴趣的读者可查看本站专题：《php加密方法总结》、《PHP编码与转码操作技巧汇总》、《PHP数学运算技巧总结》、《PHP数组(Array)操作技巧大全》、《php字符串(string)用法总结》、《PHP数据结构与算法教程》、《php程序设计算法总结》及《php正则表达式用法总结》

　　希望本文所述对大家PHP程序设计有所帮助。