<?php /** *@author:xiaojiang 20140222 * 一致性哈希php 实现 */ class MyHash{ //虚拟节点数 private $_virtualCounts = 2; //虚拟节点集合 private $_circleItems = array(); //实际节点 private $_items = array(); //实际节点数 private $_itemsCount = 0; //是否需要排序 private $_itemRelKey = array(); private $needSort = false; private $algo; public function __construct( hash_algo $algo = null ){ if( !$algo ){ $this->algo = new algo_md5(); } } public function addItem( $_item ){ if( isset( $this->_items[$_item]) ){ throw new Exception("item exists"); } $this->_items[$_item] = array(); for( $i = 0; $i < $this->_virtualCounts; $i++ ){ $_virturalKey = $this->algo->run( $_item.$i ); $this->_circleItems[$_virturalKey] = $_item; $this->_itemRelKey[$_item][] = $_virturalKey; } $this->needSort = true; $this->_itemsCount++; } public function removeItem( $_item ){ if( !isset( $this->_items[$_item] ) ){ throw new Exception("item is not exists"); } foreach( $this->_itemRelKey[$_item] as $key){ unset( $this->_circleItems[$key] ); } unset($this->_items[$_item]); $this->_itemsCount--; } public function getKey( $str ){ if($this->needSort){ $this->sortItems(); } $_sk = $this->algo->run( $str ); echo $_sk; foreach( $this->_circleItems as $key => $_item){ if( $key > $_sk ){ return $_item; } } $ret = array_values(array_slice($this->_circleItems , 0 ,1)); return $ret[0]; } private function sortItems(){ ksort( $this->_circleItems ,SORT_STRING ); $this->needSort = false; } public function _t(){ print_r($this->_circleItems); } } Interface hash_algo{ function run(); } class algo_md5{ function run( $_str ){ return MD5( $_str ); } } $_tstr = "B8aaaaa"; $thash = new MyHash(); $thash->addItem("10.100.200.3"); $thash->addItem("10.100.200.4"); //$a = $thash->getKey($_tstr); //$thash->_t(); $thash->removeItem("10.100.200.4"); $thash->_t(); ?>
主要解决多服务器的分布式选择问题。。 提高中间层服务器的部署灵活性