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：