这次给大家带来PHP实现一致性HASH算法实现步骤解析，PHP实现一致性HASH算法实现的注意事项有哪些，下面就是实战案例，一起来看一下。
<?php// +----------------------------------------------------------------------// | Perfect Is Shit// +----------------------------------------------------------------------// | PHP实现：一致性HASH算法// +----------------------------------------------------------------------// | Author: alexander <[email protected]>// +----------------------------------------------------------------------// | 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;<a>2本文来源gao*daima.com搞@代#码&网6</a><pre>搞gaodaima代码
$s = md5($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_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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