PHP实现的一致性HASH算法示例

本文实例讲述了PHP实现的一致性HASH算法。分享给大家供大家参考，具体如下：<?php//+--

本文实例讲述了PHP实现的一致性HASH算法。分享给大家供大家参考，具体如下：

<?php
// +----------------------------------------------------------------------
// | Perfect Is Shit
// +----------------------------------------------------------------------
// | PHP实现：一致性HASH算法
// +----------------------------------------------------------------------
// | Author: alexander <gt199899@gmail.com>
// +----------------------------------------------------------------------
// | Datetime: 2017-01-11 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 << $seed) + $hash + ord($s{$i});
 }
 return $hash & 0x7FFFFFFF;
 }
 /**
 * 增加节点
 * @param string $node 节点名称
 * @return object $this
 */
 public function addNode($node)
 {
 if (in_array($node, array_keys($this->nodes))) {
 return;
 }
 for ($i = 1; $i <= $this->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 <= $key) {
 $node = $value;
 break;
 }
 }
 return $node;
 }
 /**
 * 获取映射到特定节点的KEY
 * 此方法需手动调用，非特殊情况不建议程序中使用此方法
 * @param string $node
 * @param string $keyPre
 * @return mixed
 */
 public function getKey($node, $keyPre = ""){
 if(!in_array($node, array_keys($this->nodes))){
 return false;
 }
 $result = false;
 for($i=1;$i<=10000;$i++){
 $key = $keyPre . md5(rand(1000, 9999));
 if($this->getNode($key) == $node){
 $result = true;
 break;
 }
 }
 return $result ? $key : false;
 }
}
$ch_obj = new ConsistentHashing();
$ch_obj->addNode('node_1');
$ch_obj->addNode('node_2');
$ch_obj->addNode('node_3');
$ch_obj->addNode('node_4');
$ch_obj->addNode('node_5');
$ch_obj->addNode('node_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 = $ch_obj->getKey('node_1', 'pre_');
// var_dump($key1);
// +----------------------------------------------------------------------
// | 测试分布
// +----------------------------------------------------------------------
// $keys = array();
// $rings = array();
// for ($i = 1; $i <= 60000; $i++) {
// $key = sha1(rand(1000000,9999999));
// $node = $ch_obj->getNode($key);
// $rings[$node] = isset($rings[$node]) ? ++$rings[$node] : 1;
// }
// var_dump($rings);

运行结果：

asofiwjamfdalksjfkasasdflasfja 映射到节点 node_1
jaksldfjlasfjsdjfioafaslkjflsadkjfl 映射到节点 node_2
asjldflkjasfsdjflkajkldsjfksajdlflajs 映射到节点 node_1
iowanfasijfmasdnfoas 映射到节点 node_2
pqkisndfhoalnfiewlkl 映射到节点 node_3
qjklasjdifoajfalsjflsa 映射到节点 node_5

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.jb51.net/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.jb51.net/password/hash_md5_sha

PHP 一致性 HASH 算法