后端开发|php教程
HASH,一致性,php
后端开发-php教程
<?php// +----------------------------------------------------------------------// | Perfect Is Shit// +----------------------------------------------------------------------// | PHP实现：一致性HASH算法// +----------------------------------------------------------------------// | Author: alexander // +----------------------------------------------------------------------// | Datetime: -01-11 16:01:36// +----------------------------------------------------------------------// | Copyright: Perfect Is Shit// +----------------------------------------------------------------------class ConsistentHashing{ // 圆环 // hash -> 节点 private $_ring = array(); // 所有节点 // 节点 -> hash public $nodes = array(); // 每个节点的虚拟节点 public $virtual = 64; /** * 构造 * @param array $nodes 初始化的节点列表 */ public function construct($nodes = array()) { if (!empty($nodes)) {foreach ($nodes as $value) { $this->addNode($value);} } } /** * 获取圆环内容 * @return array $this->_ring */ public function getRing() { return $this->_ring; } /** * time33 函数 * @param string $str * @return 32位正整数 * @author 大神们 */ public function time33($str) { // hash(i) = hash(i-1) * 33 + str[i] // $hash = 5381; ## 将hash设置为0，竟然比设置为5381分布效果更好！！！ $hash = 0; $s = md5($str); //相比其它版本，进行了md5加密 $seed = 5; $len = 32;//加密后长度32 for ($i = 0; $i < $len; $i++) {// (hash << 5) + hash 相当于 hash * 33//$hash = sprintf("%u", $hash * 33) + ord($s{$i});//$hash = ($hash * 33 + ord($s{$i})) & 0x7FFFFFFF;$hash = ($hash <nodes))) {return; } for ($i = 1; $i virtual; $i++) {$key = $this->time33($node . - . $i);$this->_ring[$key] = $node;$this->nodes[$node][] = $key; } ksort($this->_ring, SORT_NUMERIC); return $this; } /** * 获取字符串的HASH在圆环上面映射到的节点 * @param string $key * @return string $node */ public function getNode($key) { $node = current($this->_ring); $hash = $this->time33($key); foreach ($this->_ring as $key => $value) {if ($hash nodes))){return false; } $result = false; for($i=1;$igetNode($key) == $node){ $result = true; break;} } return $result ? $key : false; }}$ch_obj = new ConsistentHashing();$ch_obj->addNode( ode_1);$ch_obj->addNode( ode_2);$ch_obj->addNode( ode_3);$ch_obj->addNode( ode_4);$ch_obj->addNode( ode_5);$ch_obj->addNode( ode_6);// +----------------------------------------------------------------------// | 查看key映射到的节点// +----------------------------------------------------------------------$key1 = "asofiwjamfdalksjfkasasdflasfja";$key2 = "jaksldfjlasfjsdjfioafaslkjflsadkjfl";$key3 = "asjldflkjasfsdjflkajkldsjfksajdlflajs";$key4 = "iowanfasijfmasdnfoas";$key5 = "pqkisndfhoalnfiewlkl";$key6 = "qjklasjdifoajfalsjflsa";echo sprintf("%-50s 映射到节点 %s\n", $key1, $ch_obj->getNode($key1));echo sprintf("%-50s 映射到节点 %s\n", $key2, $ch_obj->getNode($key2));echo sprintf("%-50s 映射到节点 %s\n", $key3, $ch_obj->getNode($key3));echo sprintf("%-50s 映射到节点 %s\n", $key4, $ch_obj->getNode($key4));echo sprintf("%-50s 映射到节点 %s\n", $key5, $ch_obj->getNode($key5));echo sprintf("%-50s 映射到节点 %s\n", $key6, $ch_obj->getNode($key6));// +----------------------------------------------------------------------// | 查看圆环和节点信息// +----------------------------------------------------------------------// var_dump($ch_obj->getRing());// var_dump($ch_obj->nodes);// +----------------------------------------------------------------------// | 获取特定节点的KEY// +----------------------------------------------------------------------// $key1 = $ch_obj->getKey( ode_1, pre_);// var_dump($key1);// +----------------------------------------------------------------------// | 测试分布// +----------------------------------------------------------------------// $keys = array();// $rings = array();// for ($i = 1; $i getNode($key);// $rings[$node] = isset($rings[$node]) ? ++$rings[$node] : 1;// }// var_dump($rings);
运行结果：
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asofiwjamfdalksjfkasasdflasfja 映射到节点 node_1jaksldfjlasfjsdjfioafaslkjflsadkjfl 映射到节点 node_2asjldflkjasfsdjflkajkldsjfksajdlflajs 映射到节点 node_1iowanfasijfmasdnfoas映射到节点 node_2pqkisndfhoalnfiewlkl映射到节点 node_3qjklasjdifoajfalsjflsa映射到节点 node_5
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