PHP實現一致性HASH演算法實現步驟解析

這次給大家帶來PHP實現一致性HASH演算法實現步驟解析，PHP實現一致性HASH演算法實現的注意事項有哪些，下面就是實戰案例，一起來看一下。

<?php// +----------------------------------------------------------------------// | Perfect Is Shit// +----------------------------------------------------------------------// | PHP實現：一致性HASH演算法// +----------------------------------------------------------------------// | Author: alexander <gt199899@gmail.com>// +----------------------------------------------------------------------// | Datetime: 2017-01-11 16:01:36// +----------------------------------------------------------------------// | Copyright: Perfect Is Shit// +----------------------------------------------------------------------class ConsistentHashing{  // 圓環  // hash -> 節點  private $_ring = array();  // 所有節點  // 節點 -> hash  public $nodes = array();  // 每個節點的虛擬節點  public $virtual = 64;  /**   * 構造   * @param array $nodes 初始化的節點列表   */  public function construct($nodes = array())  {    if (!empty($nodes)) {      foreach ($nodes as $value) {        $this->addNode($value);      }    }  }  /**   * 擷取圓環內容   * @return array $this->_ring   */  public function getRing()  {    return $this->_ring;  }  /**   * time33 函數   * @param string $str   * @return 32位正整數   * @author 大神們   */  public function time33($str)  {    // hash(i) = hash(i-1) * 33 + str[i]    // $hash = 5381; ## 將hash設定為0，竟然比設定為5381分布效果更好！！！    $hash = 0;    $s  = md5($str); //相比其它版本，進行了md5加密    $seed = 5;    $len = 32;//加密後長度32    for ($i = 0; $i < $len; $i++) {      // (hash << 5) + hash 相當於 hash * 33      //$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;  }  /**   * 增加節點   * @param string $node 節點名稱   * @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;  }  /**   * 擷取字串的HASH在圓環上面映射到的節點   * @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;  }  /**   * 擷取映射到特定節點的KEY   * 此方法需手動調用，非特殊情況不建議程式中使用此方法   * @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映射到的節點// +----------------------------------------------------------------------$key1 = "asofiwjamfdalksjfkasasdflasfja";$key2 = "jaksldfjlasfjsdjfioafaslkjflsadkjfl";$key3 = "asjldflkjasfsdjflkajkldsjfksajdlflajs";$key4 = "iowanfasijfmasdnfoas";$key5 = "pqkisndfhoalnfiewlkl";$key6 = "qjklasjdifoajfalsjflsa";echo sprintf("%-50s 映射到節點 %s\n", $key1, $ch_obj->getNode($key1));echo sprintf("%-50s 映射到節點 %s\n", $key2, $ch_obj->getNode($key2));echo sprintf("%-50s 映射到節點 %s\n", $key3, $ch_obj->getNode($key3));echo sprintf("%-50s 映射到節點 %s\n", $key4, $ch_obj->getNode($key4));echo sprintf("%-50s 映射到節點 %s\n", $key5, $ch_obj->getNode($key5));echo sprintf("%-50s 映射到節點 %s\n", $key6, $ch_obj->getNode($key6));// +----------------------------------------------------------------------// | 查看圓環和節點資訊// +----------------------------------------------------------------------// var_dump($ch_obj->getRing());// var_dump($ch_obj->nodes);// +----------------------------------------------------------------------// | 擷取特定節點的KEY// +----------------------------------------------------------------------// $key1 = $ch_obj->getKey('node_1', 'pre_');// var_dump($key1);// +----------------------------------------------------------------------// | 測試分布// +----------------------------------------------------------------------// $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);

運行結果：

asofiwjamfdalksjfkasasdflasfja           映射到節點 node_1jaksldfjlasfjsdjfioafaslkjflsadkjfl        映射到節點 node_2asjldflkjasfsdjflkajkldsjfksajdlflajs       映射到節點 node_1iowanfasijfmasdnfoas                映射到節點 node_2pqkisndfhoalnfiewlkl                映射到節點 node_3qjklasjdifoajfalsjflsa               映射到節點 node_5

相信看了本文案例你已經掌握了方法，更多精彩請關注php中文網其它相關文章！

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